Protein – by Kevin Handreck

Introduction

I have an email folder for people I’ve met on line and it’s full of characters who have contacted me for one reason or another in this wonderful virtual world. Kevin Handreck first contacted me in March 2013 and we’ve had a few exchanges of information since. I did a post on LCHF & butter at the end of January and Kevin got in touch to say he had “puzzled over what our protein intake should be.” “Puzzled over” was an understatement. Kevin sent me an impressive  36,500 word document full of analysis of scientific literature and what it had to say about protein.

I suggested to Kevin that he post it as a blog somewhere and I laughed when he replied “I don’t have a blog and at nearly 80 I don’t want to create one. I already spend too much time staring at this machine. Besides, I have just bought a bassoon. It will be enough challenge for me to learn to read music and play this instrument.” What a guy! I asked Kevin if I could share his summary and key insights openly as a guest post.

Here’s a brief bio of Kevin:

Kevin is a semi-retired scientist (chemist), who lives in Adelaide, Australia and who likes finding out how life works. He believes that good science is the only way that that goal can be achieved. He does not like the way official dietary guidelines around the world have been formulated with overwhelming inputs from food industry groups, rather than being based on honestly derived scientific findings. The information in this post is a summary of what he found in the scientific literature about the amount of protein that humans should consume for optimum health. While not part of this post, he has further concluded from independently-funded scientific studies that for optimum health our food intake should consist only of whole foods that are as unprocessed as possible. In that context, our carbohydrate intake should be low to moderate (only from cellular sources, not as flour), rich in leafy, sulphur-rich and colourful vegetables, moderate in fruit and with a high content of natural fats such as butter, extra virgin olive oil, coconut oil and animal fats.

Here’s Kevin’s article:

This article summarises what I can find about the optimum proportion of energy intake in humans that should come from protein.

1) There is a clear indication that 36%e (36% of energy) is too much protein if health problems are to be averted. At high protein intakes, it is essential to have high fat intakes as well.

2) The original Atkins and similar diets were around 35%e as protein. They allow rapid loss of fat mass if adhered to, but adherence over years was difficult, and probably unhealthy. The current ‘New Atkins for a New You’ (Westman, Phinney, Volek, 2010) says 1.2 to 2.5g/kg body weight as protein. This is roughly 16 to 33%e. This range was questioned by Jason Fung in one of his web articles, but in The Obesity Code he says 20 to 30%e, for a weight loss situation. The rationale for this high proportion of protein intake is that in a weight loss situation one is burning a lot of body fat, so the actual percentage of energy use made up by protein would be much lower than 20 to 30%, maybe only 13 to 20% of energy expenditure.

3) In a review of hunter-gatherer diets, Kuipers (2010) concluded that on average hunter-gatherers had protein intakes that made up 25 to 29% of their energy intake. Is this range biased by high intakes in the far north? Somewhat different were the data collected by Cordain (2000). He concluded that the protein intake of modern hunter-gatherers was in the range of 19 to 35%e (with CHO 22-40%e)

4) In contrast to these high protein intakes, Kitavans (Lindberg, 1997) were estimated to consume only about 10%e as protein, mainly from fish and roots. The Kitavans had a high fat intake, mainly saturated from coconuts, but also from fish. Also, Okinawans in 1950 (when they were still in calorie deficit) were estimated to consume only 39 g protein per day, or about 9%e intake. If we guess that these Okinawans would have weighed about 50 kg, then this works out at 0.78 g/kg/d. The Okinawan diet was very low in fat, especially saturated fat, so they had a high incidence of stroke.

5) Dietary guidelines all over the world derive from the WHO RDA (recommended daily allowance) of 0.8 g/kg total body weight/d, based on an EAR (estimated average requirement) of 0.66 g/kg/d and a bit of slop. This is actually a minimum level of protein intake for healthy living.

6) Dr Ron Rosedale and Dr Joseph Mercola say that protein intake should be no more than 1 g/kg lean body mass. If a 70 kg male has 20% fat, then this formula would give an intake of 56 g protein per day. On a total body mass basis this would be 0.8 g/kg, so this seems to have been copied from the minimum RDA recommendation. For the same 70 kg male with only 10% body fat, protein intake would be 63 g/d, or 0.9 g/d of total body mass. If food intake is 9000 kJ/d, these amounts of protein work out to 10.6 and 12% of total energy intake, which are similar to intakes in traditional Kitava and Okinawa, but are lower than the 14-15%e found by Raubenheimer and his co-workers to be necessary for humans (see below). Raubenheimer has shown that we eat until we have satisfied our protein intake requirements.

7) Most articles I have consulted consider an intake of 0.8 g protein per kg total body weight per day to be too little for optimum health, especially in the elderly.

8) Some papers have concluded that the efficiency of digestion and absorption of dietary protein in the elderly (70+) is lower than that for younger adults (~40), but others have found no change with aging. There is better evidence that older persons are less able to convert amino acids absorbed from food into muscle protein (anabolic resistance). But on the other hand, if food intake is preceded (within 2 hours max) by fairly vigorous exercise, this lower efficiency in the elderly is reduced or perhaps eliminated. Given the uncertainty, and the fact that not all meals can be preceded by exercise, it could be best for older people to err towards the high end of the suggested range for protein intake.

9) Cuthbertson (2004) suggests that for maximum muscle protein synthesis, an intake of 10 g essential amino acids (EAA) at any given meal is needed. An intake of about 112 g meat would provide this amount of EAA. For a 70 kg person, this would give a protein intake of 0.4 g/kg/meal. For 3 equal meals this is 1.2 g/kg/d, or a total of 84 g protein per day.

10) Rafii et al. (2016) say that for older persons, intake of protein should be about 30% higher than recommendations. They give a daily intake of 0.94 to 1.24 g/kg.

11) The Jaminets (Perfect Health Diet, 2012) say that 15%e from protein is close to optimal for most people who are eating sufficient carbs. Protein intake must be higher for those on low-carb diets. They point out that high intake of protein is correlated with shorter life, mainly due to high methionine intake. (This could be skewed by people who have mutations in their MTHFR gene(s). Such mutations raise serum homocysteine concentration via de-methylation of methionine. This is associated with many health problems. Lowering of homocysteine concentration with B vitamins in the presence of unchanged methionine intake, may negate the apparent life-shortening associated with high methionine intake.) They suggest an intake range of 50 to 150 g protein per day, which is not very helpful, but then they conclude that 15%e is a good number.

12) In older men (78 kg, BMI 25, fat 21%), Pennings (2012) found muscle protein synthesis was greater with ingestion of 35 g whey powder than with 10 or 20 g whey. Whey powder is usually 80% protein, so this is about 28 g protein. For 3 meals/day, this would be 84 g protein/day. Macnaughton (2016) found that 40 g P as whey was better than 20 g P at giving recovery from resistance training.

13) In younger men, Kim (2014) found evidence that more muscle is created when the protein intake is evenly spread over the 3 daily meals, but in older men he found that skewing of protein intake to be highest at dinner gave the same outcome as an even spread. This research suggested that 1.5 g P/kg/d was desirable, but there were no intakes between 0.8 and 1.5 g/kg.

14) Westerterp-Plantenga et al. (2004) showed that a protein intake of 18%e was better than one of 15%e. This was for those who want to maintain weight after losing fat.

15) Surdykowski (2010), Phillips (2016) and Reddy (2002) discussed the effect of protein intake on bone mass and bone loss. The first two could not find evidence of any problems for bones up to 1.6 g/kg total body mass. When Reddy increased protein intake to 2.2 g/kg, he found increased urine acidy and calcium loss.

16) Colpo (The Fat Loss Bible) says that protein intake should be in the range 1.6 to 2.5 g/kg lean The range is for sedentary persons to highly active athletes. He says a good starting point would be 2.2 g/lean kg, but he is mainly writing for those doing serious gym work. I think that Colpo overdoes the protein. Perhaps 2.0 x lean body kg would be entirely adequate. At 20% body fat, this works out at about 1.6 g/kg total weight.

17) Leidy et al. (2015) conclude that the optimum range for weight loss/maintenance is 1.2-1.6 g/kg, with 25-30 g protein at each meal. They also found that eating 35 g protein at breakfast reduced later food intake compared with no breakfast.

18) In a series of recent papers with Raubenheimer, Simpson or Gosby as first authors, the protein leverage hypothesis is developed and discussed. Based on studies of insects and animals, including baboons, orang utans and humans, they have shown that all living things eat to optimize their protein intake. If an animal has a high carb intake on one or several days it typically tries to have a higher protein intake on one or more subsequent days. For humans, this leads to a protein intake of 14-15%e. This level of protein intake is associated with satiety, such that there is no need to overeat, no need to snack. I find their data compelling. See David Raubenheimer’s talk at the NZ Ancestral Health 2015 Symposium for an excellent summary of their ideas and research. They are strongly against the older Atkins-type levels of protein intake.

19) Some of the papers that recommend a high protein intake are from labs that are supported by meat and dairy industry money. They will be biased in favour of high consumption. Wolfe even says that it could be desirable to go to a protein intake of 35%e, but his group seems to conclude that 1.2 g/kg is enough. The CSIRO ‘Total Wellbeing’ Diet, funded by the meat industry, recommends protein at 33%e, carbs at 41% and fats at 26% (full of low fat ‘goodies’, margarine and canola oil and only 6% saturated).

20) In his 2016 book The Obesity Code, Dr Jason Fung, a nephrologist in Toronto, Canada, presents his conclusion from his reading of the medical literature that it is the combination of continually elevated insulin levels and insulin resistance that are the root cause of obesity and Type 2 diabetes. Amongst many other pieces of information, he shows that protein intake raises serum insulin level through its ability to stimulate the production of the incretin hormones in our stomachs. These hormones stimulate insulin production, but this effect is countered by their ability to slow exit of the food bolus from the stomach, and therefore spread out the effect of glucose on insulin production. The net effect is neutral or even slightly positive as far as our health is concerned. Later in the book he states that he favours a protein intake of between 20 and 30% of energy intake. This is in marked contrast to his earlier statements on his blog, where he seems to say that protein intake should be a bit less than the recommended 0.8 g/kg. This difference looks like a maturing of his thoughts about protein. However, his line that suggests that protein should make up 20 to 30% of energy intake is for a weight loss situation. The remarks in Point 2 above apply here.

How to get extra protein

1) Major sources of protein are meat, fish, cheese, legume seeds, whey powder and casein powder.

2) There is much evidence that elevated body stores of iron (Fe) are a bad thing (serum ferritin should be below 100 mg/L, preferably in the 40 to 60 mg/L range), so intakes of iron should be limited to actual needs. Red meats have higher Fe levels that white meats (chicken and pork), so a case can be made for limiting red meat intake. In this context, liver intake should be low as it has the highest Fe concentration of all animal products. On the other hand, there is evidence that red meat consumption is not detrimental to our health if it is part of a mixed diet. High intake of processed meats is not good for us.

3) If a high methionine intake is indeed life shortening, then intake of sources that have the highest methionine content should be minimized. (But see point 11 above for comment.) The order in methionine content of protein sources is roughly (highest first) chicken, cheese, fish and red meats. Casein is higher than whey, so from a minimizing methionine point of view, whey seems a desirable source of any extra protein needed. Against this is the fact that whey powder intake gives a large spike in insulin production. Against all this concern about methionine are the many randomized trials and epidemiological studies that have shown that high intakes of chicken, cheese and fish are associated with long life.

4) For muscle protein synthesis, whey powder is more effective than either casein or casein hydrolysate, mainly because of its higher content of EAA (48.5% v 42%), especially leucine (12.5% v 8.5%).

Conclusion

We can go on forever about this. If we worry about it enough, we will probably counter any benefits we might get from choosing the ‘right’ level of protein intake. So what do I conclude?

The evidence seems to indicate that if one does not want to gain weight via a need to eat more to get enough protein, an intake of 14 to 16% of total energy intake is necessary. For a 70 kg person consuming 9,000 kJ/d, this is 74 to 85 g protein per day (1.06 to 1.21 g/kg total body mass per day). An intake of 0.8 g/kg (53 g/d for 70 kg older person) seems to be too little. In a weight-loss phase for those who are overweight or obese, protein intake should perhaps be up to 30%e, so that the protein also balances the energy being produced via the burning of body fat.

I therefore conclude that in a weight maintenance situation for older persons who are moderately active, a moderate protein intake that is satiating and adequate for optimum health will be in the range 1.1 to 1.2 g/kg total body weight. For a 70 kg person this is 77 to 84 g protein per day (or about 14.5 to 16%e at 9000 kJ intake per day). (A daily intake of 125 g meat or fish, 60 g cheese, 2 eggs, 100 g full-fat yoghurt or kefir, 30 g bread or 100 g potato, 400 g non-root vegetables, 50 g nuts and nut butters, 5 g whey powder would give the higher amount of protein.)

A caveat might need to be added for the elderly, because Kobayashi et al. (2017) found that frailty in elderly Japanese was associated with protein intakes of below 1.3 g/kg.

Summary of research and recommendations in the literature

(roughly in order of increasing amount of protein recommended)

(Numbers in brackets are estimated from the actual figures given in another column.)

Protein intake g/kg/d Protein as percent of total energy intake (%) Total protein for a 70 kg person (g) Total protein for a 60 kg person (g) Source Basis
0.66 46 39 WHO EAR (estimated average requirement)
0.8 56 48 WHO RDA (recommended minimum daily allowance)
0.78 for 50 kg 9 55 47 Okinawa 1949 (Willcox 2007) Actual measurement 39 g/d
0.83 58 50 Rand (2003) Healthy adults, meta-analysis of excretion balance studies
(0.84) 10 53 (9000 kJ intake) 45 Kitava (Lindberg 1997) Estimate from food intake and tables
(0.84, 0.84-1.6, >1.7) 10%, 10-19%, >20% 53, 53-100, >106 48, 48-91, >96 Levine (2014) Low best during middle age; moderate to high best in older persons for lowest mortality
>0.8 >56 >48 Campbell (2001) In elderly, some loss of thigh muscle at 0.8 g/kg
>0.8 >56 >48 Surdykowski (2010) Said more than 0.8g/kg will improve bone strength
0.8-1.2 (of ideal body weight) 56 to 84 48 to 72 Kemp and Daly (2016) They say that this is ‘moderate’ for a keto diet.
0.9 63 54 Rosedale, R Quoted in Keto Clarity. 1 g/kg ideal weight, minus 10% (ie. 1 g/kg of lean body mass for lean person)
10-15 53 to 79 45 to 68 Greenfield, B Quoted in Keto Clarity
1.0 70 60 Apolzan (2007) 1 g/kg reduced hunger pangs more than 0.75 g/kg
1.0 70 60 Houston DK et al. 2017 >= 1.0 g/kg for older persons
1.06 to 1.2 74 to 84 63 to 72 Krieger JW et al. (2006) Maximum muscle synthesis was in this range. (It was lower at lower and higher P intakes.)
1.08 76 65 Pennings (2012) Whey powder as source of P; 35 g better than 10 0r 20 g. This was equivalent to 84 g P/d for 78 kg person.
1.13 for 60 kg 13 79 68 Japan 1950 (Willcox 2007) Actual measurement 68 g/d
1.13 79 68 Verreijen AM et al. 2017 For oldies, need resistance exercise to accompany. 0.98 g/kg/d not enough.
70 to 80 55-70 Petersen, Grant: Eat bacon; don’t jog 30 g P/meal, or 70 to 80 g P/d for ‘normal’ male
1.2 84 72 Cuthbertson (2004) Maximum muscle protein synthesis (essential amino acid amount of 10 g/meal = 30 g/d
1.2 84 72 Soenen (2013) Needed to maintain health during and after fat loss.
0.72 to 1.2 50 to 84 43 to 72 Moore (2015) Based on 22 years of data, 0.4 g/kg at each meal for elderly and 0.24 g/kg for young for maximum muscle protein synthesis
0.93 to 1.2 65 to 84 56 to 72 Elango (2010) Re-analysis of older data, and new data
0.94 to 1.24 66 to 87 57 to 75 Rafii (2016) For elderly, 30% higher than RDA
14.7 Campbell (2015) Self-selected by survivors of malnutrition
14 to 15 82 to 88 70 to 75 Papers by Raubenheimer, Simpson, Gosby Adequate amount of P to maintain weight and health, based on evolutionary concepts and trials.
14-15 82 to 88 70 to 75 Raubenheimer NZ Ancestral Health talk (2015) 14-15%e needed
15 88 (9000 kJ intake) 75 Gosby (2014) Lowering protein from 15%e to 10%e increased snacking
15 88 75 Jaminet (2012) Search of the literature
0.8 to 1.5 56 to 105 48 to 90 Kim (2014) Trial. 1.5 g/kg better muscle P synthesis than at 0.8 g/kg
90 77 Porter Star (2016) For frail older people, need 30 g/meal.
>1 >70 (60-90) >60 (60-90) Layman (2015) 20-30 g P per meal
(1.2) 15 to 20 (84) 88 to 118 (72) 75 to 101 Wolfe 2008, 2012; Baum 2016 Conclude that 1.2 g/kg (or 15 to 20%e) is best (Bias from meat industry funds???)
(1.6) 18.9 111 95 Shai (2008) Israeli trial. Assumed 18.9% protein in Mediterranean diet, because Willett said so!
1.2 to 1.6 84 to 112 72 to 96 Leidy (2015) Based on effect on later food intake after 35 g P meal.
1.2-1.7 84 to 119 72 to 102 Phinney (2004) Based on ‘reference body weight’
1.3-1.5 90 to 104 77 to 89 Kobayashi (2017) Frailty in elderly Japanese associated with <1.3 g/kg protein (51 kg mean).
1.6 112 96 Colpo (2009) 1.6 to 2.5 g/kg lean mass (sedentary to top athlete)
1.2 to 1.6 84 to 112 72 to 96 Phillips (2016) Review. 1.2 to 1.6 g/kg range best for optimum health (and no bone loss)
1.5 to 2 (15 to 25) 105 to 140 90 to 120 Volek and Phinney (2011) Especially for those with brittle bones, but they say elsewhere that no-one has ever shown that >1.5 g/kg benefits health
(1.2 to 2.5) (16-33) 84 to 175 72 to 150 Westman, Phinney and Volek (2010) The New Atkins for a New You They base protein intake primarily on height and gender, but modified by individual variation.
15 to 30 88 to106 75 to 91 Westerterp-Plantenga (2004) A decrease in P intake from 18%e to 15%e caused greater weight regain after loss.
1.1 to <2.2 77 to 154 (over the top) 66 to 132 Reddy (2002) Increasing P intake from 91 to 170 g/d (81.4 kg persons) gave greater acidity and Ca loss. 2.2 g/kg is too much.
19-35 100 to 185 86 to 158 Cordain (2000) Based on studies of contemporary hunter-gaatherers
25 to 29 147 to 170 126 to 146 Kuipers (2010) Estimates for hunter-gatherers. How reliable??
20 to 30 118-176 101 to 151 Fung (2016) He considers this range to be moderate, but it is for a weight loss situation where body fat is being burnt.
33 175 150 CSIRO ‘Total Wellbeing’ Diet Funded by the meat industry

Research articles on protein: chronological order

Rudman D, et al. 1973 Maximal rates of excretion and synthesis of urea in normal and cirrhotic subjects. J Clin Invest. 1973 Sep;52(9):2241-9. Attempt to set the upper limit for protein intake on the basis absence of adverse effects of urea excretion.
Castaneda C et al. 1995 Elderly women accommodate to a low-protein diet with losses of body cell mass, muscle function, and immune response. Am J Clin Nutr. 62(1):30-9. At a low protein intake, elderly women lose lean tissue, immune response and muscle function.
Lindberg, S et al.1997 Age relations of cardiovascular risk factors in a traditional Melanesian society: the Kitava Study. Am J Clin Nutr 66:845-52. Estimated P intake was 10%e.
Holt SH et al. 1997 An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods. Am J Clin Nutr. 1997 Nov;66(5):1264-76. Protein intake causes a release of insulin that is somewhat higher than release elicited by a similar amount of carbs.
Hu FB et al. 1999 Dietary protein and risk of ischemic heart disease in women. Am J Clin Nutr. 1999 Aug;70(2):221-7. Replacing carbs with protein seemed to reduce heart disease
Munger, RG et al. 1999 Prospective study of dietary protein intake and risk of hip fracture in postmenopausal women1,2,3 Am J Clin Nutr January 1999 vol. 69 no. 1 147-152. Intake of dietary protein, especially from animal sources, may be associated with a reduced incidence of hip fractures in postmenopausal women.
Cordain, L et al. 2000 Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. Am J Clin Nutr 71:682–92 Most hunter-gatherers consume more than 50%e as animal products; only 14% of those studied had >50% from gathered foods. Protein intake was 19-35%e, carbs 22-40%.
Esmarck, B et al. 2001 Timing of post-exercise protein intake is important for muscle hypertrophy with resistance training in elderly humans. Journal of Physiology 535.1, pp.301–311. Eat protein as soon as possible after resistance training for optimum muscle building in the elderly.
Campbell, WW, et al. 2001 The Recommended Dietary Allowance for Protein May Not Be Adequate for Older People to Maintain Skeletal Muscle. Journal of Gerontology: MEDICAL SCIENCES 56A, No. 6, M373–M380. An intake of 0.8 g protein/kg body weight is not enough for older people
Reddy ST, et al 2002 Effect of low-carbohydrate high-protein diets on acid-base balance, stone-forming propensity, and calcium metabolism. Am J Kidney Dis. 40(2):265-74. A low carb/high protein diet leads to calcium loss, acidity and kidney stones. But how high was high protein?
Rand WM et al. 2003 Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults. Am J Clin Nutr. 2003 Jan;77(1):109-27. This meta-analysis provides new recommendations for dietary reference values, ie, an EAR (median) and RDA (97.5th percentile) for healthy adults of 105 and 132 mg N x kg(-1) x d(-1) (0.65 and 0.83 g good-quality protein x kg(-1) x d(-1)), respectively.
Foster, GD et al. 2003 A Randomized Trial of a Low-Carbohydrate Diet for Obesity. N Engl J Med 2003;348:2082-90. Low CHO gave better health markers.
Halton TL and Hu FB 2004 The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review. J Am Coll Nutr. 2004 Oct;23(5):373-85 High protein intake leads to reduced energy intake and weight gain.
Simpson SJ et al. 2004 Optimal foraging when regulating intake of multiple nutrients. ANIMAL BEHAVIOUR, 2004, 68, 1299–1311 doi:10.1016/j.anbehav.2004.03.003. Mainly about insects and how they regulate food intake. Prelude to Protein leverage concept.
Due, A et al. 2004 Effect of normal-fat diets, either medium or high in protein, on body weight in overweight subjects: a randomised 1-year trial. Int J Obes Relat Metab Disord. 28:1283-90. A diet with 30%e from fat and 12 or 25% from protein showed that at the higher protein intake, weight loss was greater than at the lower intake.
Evans, WJ 2004 Protein Nutrition, Exercise and Aging. Journal of the American College of Nutrition, 23: 601S–609S. During resistance training and for the very old, a protein intake of up to 1.6 g/kg was necessary for muscle maintenance.
Westerterp-Plantenga MS et al. 2004 High protein intake sustains weight maintenance after body weight loss in humans. Int J Obes Relat Metab Disord. 2004 Jan;28(1):57-64. Protein intake should be 18%e, which for 10,000 kJ intake is 106 g P/d.
Cuthbertson, D et al. 2004 Anabolic signaling deficits underlie amino acid resistance of wasting, aging muscle. The FASEB Journal express article10.1096/fj.04-2640fje. The elderly should eat much of their protein intake very soon after exercise.
Phinney SD 2004 Ketogenic diets and physical performance. Nutr Metab (Lond). 2004 Aug 17;1(1):2. Says 1.2-1.7 g protein per kg reference body weight. I think that this is ‘ideal’ body weight.
Simpson SJ and Raubenheimer D. 2005 Obesity: the protein leverage hypothesis. Obes Rev. 2005 May;6(2):133-42. First paper on protein leverage – the hypothesis that living creatures try to optimise protein intake.
Raubenheimer D et al. 2005 Does Bertrand’s rule apply to macronutrients? Proc Biol Sci. 2005 Nov 22;272(1579):2429-34. Increased CHO intake increases morbitity.
Bonjour JP 2005 Dietary protein: an essential nutrient for bone health. J Am Coll Nutr. 2005 Dec;24(6 Suppl):526S-36S. Dietary proteins are as essential as calcium and vitamin D for bone health and osteoporosis prevention. No consistent evidence that veg protein is superior to animal protein.
Weigle, DS et al. 2005 A high-protein diet induces sustained reductions in appetite, ad- libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations. Am J Clin Nutr 82:41– 8. Raising protein intake from 15 to 30%e at constant carbs intake had an anorexic effect – it decreased energy intake.
Krieger JW et al. 2006 Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression. Am J Clin Nutr. 2006 Feb;83(2):260-74. There is a metabolic advantage to be had from low carb/high protein intakes. The found that optimum muscle synthesis was from 1.06 to 1.2 g/kg protein intake.
Koopman, R et al. 2006 Co-ingestion of protein and leucine stimulates muscle protein synthesis rates to the same extent in young and elderly lean men. Am J Clin Nutr 84:623–32. Co-ingestion of protein and leucine with carbohydrate after activities of daily living improves whole-body protein balance, in both lean young and elderly men.
Halkjær, J et al. 2006 Intake of macronutrients as predictors of 5-y changes in waist Circumference. Am J Clin Nutr 84:789 –97. Increased protein intake gave less increase in waist circumference.
Hodgson, JM et al. 2007 Increased Lean Red Meat Intake Does Not Elevate Markers of Oxidative Stress and Inflammation in Humans. J.Nutr. 137: 363–367. As it says.
Apolzan, JW et al. 2007 Inadequate Dietary Protein Increases Hunger and Desire to Eat in Younger and Older Men. J Nutr. 137(6): 1478–1482. Ratings of hunger were lower after consuming meals with protein at 1.0 g/kg than at 0.75 or 0.5 g/kg.
Willcox, BJ et al 2007 Caloric Restriction, the Traditional Okinawan Diet, and Healthy Aging The Diet of the World’s Longest-Lived People and Its Potential Impact on Morbidity and Life Span. Ann. N.Y. Acad. Sci. 1114: 434–455 (2007). doi: 10.1196/annals.1396.037434 1949 protein intake was about 9%e (39 g/d. Japan 1950 was 68 g (13%e)
Wolfe RR et al. 2008 Optimal protein intake in the elderly. Clin Nutr. 2008 Oct;27(5):675-84. doi: 10.1016/j.clnu.2008.06.008. Epub 2008 Sep 25. Advocates 1.5 g/kg/d as optimum protein intake.
Madsen, L t al. 2008 cAMP-dependent Signaling Regulates the Adipogenic Effect of n-6 Polyunsaturated Fatty Acids. J Biol Chem 283:7196. Omega-6 PUFA are adipogenic when combined with a high carbohydrate diet, but are not adipogenic when combined with a high protein (and low carbohydrate) diet
Koopman, R et al. 2008 Co-ingestion of leucine with protein does not further augment post-exercise muscle protein synthesis rates in elderly men. British Journal of Nutrition 99, 571–580. There is no need to supplement with leucine after exercise if protein intake is adequate.
Koopman, R, et al. 2009 Dietary Protein Digestion and Absorption Rates and the Subsequent Postprandial Muscle Protein Synthetic Response Do Not Differ between Young and Elderly Men. J. Nutr. 139:1707–1713,. Healthy older men are capable of using casein as a source of protein.
Koopman, R, et al. 2009 Ingestion of a protein hydrolysate is accompanied by an accelerated in vivo digestion and absorption rate when compared with its intact protein. Am J Clin Nutr 90:106–15. Intake of hydrolysed casein gave greater muscle building than intact casein.
Gannon MC and Nuttall, FQ 2010 Amino Acid Ingestion and Glucose Metabolism—A Review. IUBMB Life, 62(9): 660–668. Many amino acids slightly increase insulin secretion, but some decrease it. The overall effect is small or nil for a mixture of amino acids.
Leidy HJ et al. 2010 The influence of higher protein intake and greater eating frequency on appetite control in overweight and obese men. Obesity (Silver Spring). 2010 Sep;18(9):1725-32. doi: 10.1038/oby.2010.45. Extra protein beneficial to obese men; increased eating frequency counterproductive.
Elango R et al. 2010 Evidence that protein requirements have been significantly underestimated. Curr Opin Clin Nutr Metab Care. 2010 Jan;13(1):52-7. doi: 10.1097/MCO.0b013e328332f9b7. Present evidence that optimum protein intake is 0.93 to 1.2 g/kg/d.
Gosby AK et al. 2010 Design and testing of foods differing in protein to energy ratios. Appetite. 2010 Oct;55(2):367-70. doi: 10.1016/j.appet.2010.06.009. Details of experimental diets for different protein contents.
Westman, EC, Phinney, SD and Volek, JS (2010) The New Atkins for a New You. Touchstone. Update on the original Atkins diet, with modifications based on the most recent science to that date.
Surdykowski AK et al 2010 . Optimizing bone health in older adults: the importance of dietary protein. Aging health. 6(3):345-357. For optimum bone health, the elderly should eat more protein than the official 0.8 g/kg/d.
Kuipers RS et al. 2010 Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet. Br J Nutr. 104(11):1666-87. doi: 10.1017/S0007114510002679. Food intake in this population was about 28%e from protein, 35% from fats and 40% from carbs.
Volek JS and Phinney, SD 2011 The art and science of low carbohydrate living Book
Gosby AK et al. 2011 Testing protein leverage in lean humans: a randomised controlled experimental study. PLoS One. 2011;6(10):e25929. doi: 10.1371/journal.pone.0025929. Decreasing protein intake from 15%e to 10%e caused an increase in total energy consumption.
Raubenheimer, D 2011 Toward a quantitative nutritional ecology: the right-angled mixture triangle. Ecological Monographs 81, Issue 3 August 2011 Pages 407–427 DOI: 10.1890/10-1707.1 Description of the ProteinCarbsFat triangle for plotting nutrient ratios.
Kerstetter JE et al. 2011 Dietary protein and skeletal health: a review of recent human research. Curr Opin Lipidol. 2011 Feb;22(1):16-20. doi: 10.1097/MOL.0b013e3283419441. Dietary protein works synergistically with calcium to improve calcium retention and bone metabolism. Do not restrict protein intake!
Pennings, B et al. 2011 Exercising before protein intake allows for greater use of dietary protein–derived amino acids for de novo muscle protein synthesis in both young and elderly men. Am J Clin Nutr 93:322–31 Exercising before protein intake maximises its use in muscle building.
Pennings, B, et al. 2011 Whey protein stimulates postprandial muscle protein accretion more effectively than do casein and casein hydrolysate in older men. Am J Clin Nutr 93:997–1005. Whey is better at building muscle than is casein.
Pennings, B et al. 2012 Amino acid absorption and subsequent muscle protein accretion following graded intakes of whey protein in elderly men. Am J Physiol Endocrinol Metab 302: E992–E999, 2012. We conclude that ingestion of 35 g whey protein results in greater amino acid absorption and subsequent stimulation of de novo muscle protein synthesis compared with the ingestion of 10 or 20 g whey protein in healthy, older men.
Roberts, RO et al. 2012 Relative Intake of Macronutrients Impacts Risk of Mild Cognitive Impairment or dementia. J Alzheimers Dis. 32:329. High carbs, low fat/low protein diet is associated with increased risk of dementia in the aged.
Ebbeling CB et al. 2012 Effects of dietary composition on energy expenditure during weight-loss maintenance. JAMA. 2012 Jun 27;307(24):2627-34. doi: 10.1001/jama.2012.6607. Decreases in REE and TEE were lowest with a low carb diet.
Lorenzen, J et al. 2012 The effect of milk proteins on appetite regulation and diet-induced thermogenesis European Journal of Clinical Nutrition 66, 622-627. Milk reduced subsequent energy intake more than isocaloric drinks containing only whey or casein.
Churchward-Venne, TA et al. 2012 Nutritional regulation of muscle protein synthesis with resistance exercise: strategies to enhance anabolism. Nutrition & Metabolism 2012, 9:40 Review article. Not much info in the abstract. Dietary strategies for maximising muscle protein synthesis during resistance exercise.
Wolfe RR 2012 The role of dietary protein in optimizing muscle mass, function and health outcomes in older individuals. Br J Nutr. 2012 Aug;108 Suppl 2:S88-93. doi: 10.1017/S0007114512002590. No problems in elderly from intake of higher amounts of protein above 0.8 g/kg/d.
Churchward-Venne TA et al. 2013 Role of protein and amino acids in promoting lean mass accretion with resistance exercise and attenuating lean mass loss during energy deficit in humans. Amino Acids. 2013 Aug;45(2):231-40. doi: 10.1007/s00726-013-1506-0. Epub 2013 May 5. Additionally, overfeeding energy with moderate to high-protein intake (15-25 % protein or 1.8-3.0 g kg⁻¹ day⁻¹) is associated with lean, but not fat mass accretion,
Lee, JE et al. 2013 Meat intake and cause-specific mortality: a pooled analysis of Asian prospective cohort studies. Am J Clin Nutr 2013;98:1032–41. Our pooled analysis did not provide evidence of a higher risk of mortality for total meat intake and provided evidence of an inverse association with red meat, poultry, and fish/seafood. Red meat intake was inversely associated with CVD mortality in men and with cancer mortality in women in Asian countries.
Burd, NA et al. 2013 Anabolic Resistance of Muscle Protein Synthesis With Aging. Exerc Sport Sci Rev. 41(3):169173. Protein source, amount and time in relation to exercise all need to be considered in assessing protein adequacy for muscle building.
Soenen, S et al. 2013 Normal Protein Intake Is Required for Body Weight Loss and Weight Maintenance, and Elevated Protein Intake for Additional Preservation of Resting Energy Expenditure and Fat Free Mass1,2First published February 27, 2013, doi: 10.3945/​jn.112.167593 Need 1.2 g/kg for healthy weight loss and maintenance afterwards.
Gosby AK et al. 2014 Protein leverage and energy intake. Obes Rev. 2014 Mar;15(3):183-91. doi: 10.1111/obr.12131. Diluting protein intake with either CHO or fat had the same effect of increasing energy intake.
Kim, I-Y et al. 2014 Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults. Am J Physiol Endocrinol Metab 308: E21–E28, 2015. 1.5 g/kg/d was better than 0.8 g/kg/d in maintaining muscle protein synthesis, but where is the peak?
Levine ME et al. 2014 Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population. Cell Metab. 2014 Mar 4;19(3):407-17. doi: 10.1016/j.cmet.2014.02.006. 10%e as protein during middle age best; moderate to high protein (10-19%e or >20%e) were better in older people.
Mamerow, MM et al. 2014 Dietary Protein Distribution Positively Influences 24-h Muscle Protein Synthesis in Healthy Adults. J. Nutr. 144: 876–880 It is best to spread total protein intake fairly evenly across the meals of a day.
Binnie MA et al. 2014 Red meats: time for a paradigm shift in dietary advice. Meat Sci. 2014 Nov;98(3):445-51. doi: 10.1016/j.meatsci.2014.06.024. It is time for dietary advice that emphasizes the value of unprocessed red meat as part of a healthy balanced diet.
Leidy HJ et al. 2015 The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015 Apr 29. pii: ajcn084038. They say optimum protein intake is 1.2-1.6 g/kg body mass, and 25-30 g protein per meal.
Layman DK et al. 2015 Defining meal requirements for protein to optimize metabolic roles of amino acids. Am J Clin Nutr. 2015 Apr 29. pii: ajcn084053. >1 g/kg/d but more importantly 20-30 g P per meal
Leidy HJ et al. 2015 A high-protein breakfast prevents body fat gain, through reductions in daily intake and hunger, in “Breakfast skipping” adolescents. Obesity (Silver Spring). 2015 Sep;23(9):1761-4. doi: 10.1002/oby.21185. 35 g P at breakfast gave better health outcomes than no breakfast in adolescents.
Moore, DR et al. 2015 Protein Ingestion to Stimulate Myofibrillar Protein Synthesis Requires Greater Relative Protein Intakes in Healthy Older Versus Younger Men. J Gerontol A Biol Sci Med Sci doi:10.1093/gerona/glu103 Our data suggest that healthy older men ….require a greater relative protein intake, in a single meal, than young men to maximally stimulate postprandial rates of MPS
Martens EA et al. 2015 Maintenance of energy expenditure on high-protein vs. high-carbohydrate diets at a constant body weight may prevent a positive energy balance. Clin Nutr. 2015 Oct;34(5):968-75. doi: 10.1016/j.clnu.2014.10.007. They compared 30% P with 5% P and got the obvious result.
Bauer LB, et al. 2015 A pilot study examining the effects of consuming a high-protein vs normal-protein breakfast on free-living glycemic control in overweight/obese ‘breakfast skipping’ adolescents. Int J Obes (Lond). 39(9):1421-4. doi: 10.1038/ijo.2015.101. These data suggest that the daily addition of a HP breakfast, containing 35 g of high-quality protein, has better efficacy at improving free-living glycemic control compared with a NP breakfast in overweight/obese, but otherwise healthy, ‘breakfast skipping’ adolescents.
Doering, TM et al. 2015 Post-Exercise Dietary Protein Strategies to Maximize Skeletal Muscle Repair and Remodeling in Masters Endurance Athletes: A Review. International Journal of Sport Nutrition and Exercise Metabolism DOI: http://dx.doi.org/10.1123/ijsnem.2015-0102 masters athletes may benefit from higher doses of post-exercise dietary protein, with particular attention directed to the leucine content of the post-exercise bolus.
Campbell, CP et al. 2015 Developmental contributions to macronutrient selection: a randomized controlled trial in adult survivors of malnutrition. Evolution, Medicine, and Public Health [2015] pp. 158–169. doi:10.1093/emph/eov030 The human subjects self-selected food intake that provided 14.7%e as protein. Lower protein intakes are associated with weight gain.
Raubenheimer D et al. 2015 Geometry of nutrition in field studies: an illustration using wild primates. Oecologia. 2015 Jan;177(1):223-34. doi: 10.1007/s00442-014-3142-0. Gorillas choose their food to optimise protein intake.
Raubenheimer D et al. 2015 Nutritional ecology of obesity: from humans to companion animals. Br J Nutr. 2015 Jan;113 Suppl:S26-39. doi: 10.1017/S0007114514002323. Humans optimise protein intake, as do domesticated animals. Effect of rising CO2 on nutrient density.
Song, M et al. 2016 Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality FREE ONLINE FIRST. See Zoe Harcombe’s demolishing of this junk.
Churchward-Venne TA et al. 2016 What is the Optimal Amount of Protein to Support Post-Exercise Skeletal Muscle Reconditioning in the Older Adult? Sports Med. 2016 Feb 19. [Epub ahead of print] Older athletes should have a post-workout protein intake of about 40 g.
Phillips SM et al. 2016 Protein “requirements” beyond the RDA: implications for optimizing health. Appl Physiol Nutr Metab. 2016 Feb 9:1-8. 1.2 to 1.6 g P/kg is the optimal range. (83-110 g P/d for 69 kg person.)
Rafii M et al. 2016 Dietary Protein Requirement of Men >65 Years Old Determined by the Indicator Amino Acid Oxidation Technique Is Higher than the Current Estimated Average Requirement. J Nutr. 2016 Mar 9. pii: jn225631. 0.94-1.24 g P/kg is best for older men. This is about 30% higher than standard recommendations.
Rittig N et al. 2016 Anabolic effects of leucine-rich whey protein, carbohydrate, and soy protein with and without β-hydroxy-β-methylbutyrate (HMB) during fasting-induced catabolism: A human randomized crossover trial. doi:10.1016/j.clnu.2016.05.004 These novel findings suggest that leucine-rich whey protein and/or HMB (β-hydroxy-β-methylbutyrate) are specifically beneficial during fasting-induced catabolic conditions.
Berryman CE et al. 2016 Diets higher in animal and plant protein are associated with lower adiposity and do not impair kidney function in US adults. Am J Clin Nutr. 2016 Jul 27. pii: ajcn133819. Eat plenty of protein for weight loss.
Macnaughton LS et al. 2016 The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein. doi: 10.14814/phy2.12893 Physiol Rep, 4 (15), 2016, e12893, Intake of 40 g protein gave greater muscle synthesis than did 20 g protein after workout.
Baum JI and Wolfe RR 2016 The Link between Dietary Protein Intake, Skeletal Muscle Function and Health in Older Adults. Nutrients 2016, 8, 359; doi:10.3390/nu8060359 Review. They conclude that we need a higher protein intake than the recommended 0,8 g/kg total body mass.
Porter Starr KN et al. 2016 Improved Function With Enhanced Protein Intake per Meal: A Pilot Study of Weight Reduction in Frail, Obese Older Adults. J Gerontol A Biol Sci Med Sci. 2016 Oct;71(10):1369-75. doi: 10.1093/gerona/glv210. For elderly, 30 g P/meal better than lower amounts that were not specified in the abstract.
Fretts AM et al. 2016 Processed Meat, but Not Unprocessed Red Meat, Is Inversely Associated with Leukocyte Telomere Length in the Strong Heart Family Study. J Nutr. 2016 Oct;146(10):2013-2018. Epub 2016 Aug 24. Processed meat consumption associated with reduced Telomere length. Red meat is not.
Fekete ÁA et al. 2016 Whey protein lowers blood pressure and improves endothelial function and lipid biomarkers in adults with prehypertension and mild hypertension: results from the chronic Whey2Go randomized controlled trial. Am J Clin Nutr. 2016 Oct 26. pii: ajcn137919. Says that consumption of unhydrolised whey protein reduces hypertension.
de Batlle J et al. 2016 Meat intake, cooking methods and doneness and risk of colorectal tumours in the Spanish multicase-control study (MCC-Spain). Eur J Nutr. 2016 Nov 24. Cooking meat at a high temperature promotes colorectal cancer.
O’Connor LE et al. 2016 Total red meat intake of ≥0.5 servings/d does not negatively influence cardiovascular disease risk factors: a systemically searched meta-analysis of randomized controlled trials. Am J Clin Nutr. 2016 Nov 23. pii: ajcn142521. (See Zoe Harcombe here)
Durosier-Izart C et al. 2017 Peripheral skeleton bone strength is positively correlated with total and dairy protein intakes in healthy postmenopausal women. Am J Clin Nutr. 2017 Jan 11. pii: ajcn134676. doi: 10.3945/ajcn.116.134676. High protein intake promotes bone strength.
Verreijen AM et al. 2017 Effect of a high protein diet and/or resistance exercise on the preservation of fat free mass during weight loss in overweight and obese older adults: a randomized controlled trial. Nutr J. 2017 Feb 6;16(1):10. doi: 10.1186/s12937-017-0229-6. 1.13 g/kg/d better than 0.98 g/kg/d for maintaining muscle mass in oldies, but it must be accompanied by resistance exercise.
Mangano KM et al. 2017 Dietary protein is associated with musculoskeletal health independently of dietary pattern: the Framingham Third Generation Study. Am J Clin Nutr. 2017 Mar;105(3):714-722. doi: 10.3945/ajcn.116.136762. Lowest protein intake gave less muscle and muscle strength.
Houston DK et al. 2017 Protein Intake and Mobility Limitation in Community-Dwelling Older Adults: the Health ABC Study. J Am Geriatr Soc. 2017 Mar 17. doi: 10.1111/jgs.14856. These results suggest that protein intakes of ≥1.0 g/kg body weight/d may be optimal for maintaining physical function in older adults.
Nieva-Echevarría, B et al. 2017 Effect of the presence of protein on lipolysis and lipid oxidation occurring during in vitro digestion of highly unsaturated oils. DOI: 10.1016/j.foodchem.2017.05.028 ?? protein digestion seems to protect PUFA from oxidation.
Kobayashi, S et al. 2017 Diet with a combination of high protein and high total antioxidant capacity is strongly associated with low prevalence of frailty among old Japanese women: a multicenter cross-sectional study. Nutrition Journal.
https://doi.org/10.1186/s12937-017-0250-9
Evidence that less than 1.3 g/kg is associated with frailty. Optimum is 1.3-1.5 g/kg for 51 kg elderly Japanese.

Alphabetical listing

Apolzan, JW et al. 2007 Inadequate Dietary Protein Increases Hunger and Desire to Eat in Younger and Older Men. J Nutr. 137(6): 1478–1482.

Bauer LB, et al. 2015 A pilot study examining the effects of consuming a high-protein vs normal-protein breakfast on free-living glycemic control in overweight/obese ‘breakfast skipping’ adolescents. Int J Obes (Lond). 39(9):1421-4. doi: 10.1038/ijo.2015.101.

Baum JI and Wolfe RR 2016 The Link between Dietary Protein Intake, Skeletal Muscle Function and Health in Older Adults. Nutrients 2016, 8, 359; doi:10.3390/nu8060359

Berryman CE et al. 2016 Diets higher in animal and plant protein are associated with lower adiposity and do not impair kidney function in US adults. Am J Clin Nutr. 2016 Jul 27. pii: ajcn133819.

Binnie MA et al. 2014 Red meats: time for a paradigm shift in dietary advice. Meat Sci. 2014 Nov;98(3):445-51. doi: 10.1016/j.meatsci.2014.06.024.

Bonjour JP 2005 Dietary protein: an essential nutrient for bone health. J Am Coll Nutr. 2005 Dec;24(6 Suppl):526S-36S.

Burd, NA et al. 2013 Anabolic Resistance of Muscle Protein Synthesis With Aging. Exerc Sport Sci Rev. 41(3):169173.

Campbell, WW, et al. 2001 The Recommended Dietary Allowance for Protein May Not Be Adequate for Older People to Maintain Skeletal Muscle. Journal of Gerontology: MEDICAL SCIENCES 56A, No. 6, M373–M380.

Campbell, CP et al. 2015 Developmental contributions to macronutrient selection: a randomized controlled trial in adult survivors of malnutrition. Evolution, Medicine, and Public Health [2015] pp. 158–169 doi:10.1093/emph/eov030.

Castaneda C et al. 1995 Elderly women accommodate to a low-protein diet with losses of body cell mass, muscle function, and immune response. Am J Clin Nutr. 62(1):30-9.

Churchward-Venne, TA et al. 2012 Nutritional regulation of muscle protein synthesis with resistance exercise: strategies to enhance anabolism. Nutrition & Metabolism 2012, 9:40

Churchward-Venne TA et al. 2013 Role of protein and amino acids in promoting lean mass accretion with resistance exercise and attenuating lean mass loss during energy deficit in humans. Amino Acids. 2013 Aug;45(2):231-40. doi: 10.1007/s00726-013-1506-0. Epub 2013 May 5.

Churchward-Venne TA et al. 2016 What is the Optimal Amount of Protein to Support Post-Exercise Skeletal Muscle Reconditioning in the Older Adult? Sports Med. 2016 Feb 19. [Epub ahead of print]

Cordain, L et al. 2000 Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. Am J Clin Nutr 71:682–92

Cuthbertson, D et al. 2004 Anabolic signaling deficits underlie amino acid resistance of wasting, aging muscle. The FASEB Journal express article10.1096/fj.04-2640fje..

de Batlle J et al. 2016 Meat intake, cooking methods and doneness and risk of colorectal tumours in the Spanish multicase-control study (MCC-Spain). Eur J Nutr. 2016 Nov 24.

Doering, TM et al. 2015 Post-Exercise Dietary Protein Strategies to Maximize Skeletal Muscle Repair and Remodeling in Masters Endurance Athletes: A Review. International Journal of Sport Nutrition and Exercise Metabolism. DOI: http://dx.doi.org/10.1123/ijsnem.2015-0102

Due, A et al. 2004 Effect of normal-fat diets, either medium or high in protein, on body weight in overweight subjects: a randomised 1-year trial. Int J Obes Relat Metab Disord. 28:1283-90.

Durosier-Izart C et al. 2017 Peripheral skeleton bone strength is positively correlated with total and dairy protein intakes in healthy postmenopausal women. Am J Clin Nutr. 2017 Jan 11. pii: ajcn134676. doi: 10.3945/ajcn.116.134676.

Ebbeling CB et al. 2012 Effects of dietary composition on energy expenditure during weight-loss maintenance. JAMA. 2012 Jun 27;307(24):2627-34. doi: 10.1001/jama.2012.6607.

Elango R et al. 2010 Evidence that protein requirements have been significantly underestimated. Curr Opin Clin Nutr Metab Care. 2010 Jan;13(1):52-7. doi: 10.1097/MCO.0b013e328332f9b7.

Esmarck, B et al. 2001 Timing of post-exercise protein intake is important for muscle hypertrophy with resistance training in elderly humans. Journal of Physiology 535.1, pp.301–311.

Evans, WJ 2004 Protein Nutrition, Exercise and Aging. Journal of the American College of Nutrition, 23: 601S–609S.

Fekete ÁA et al. 2016 Whey protein lowers blood pressure and improves endothelial function and lipid biomarkers in adults with prehypertension and mild hypertension: results from the chronic Whey2Go randomized controlled trial. Am J Clin Nutr. 2016 Oct 26. pii: ajcn137919.

Foster, GD et al. 2003 A Randomized Trial of a Low-Carbohydrate Diet for Obesity. N Engl J Med 2003;348:2082-90.

Fretts AM et al. 2016 Processed Meat, but Not Unprocessed Red Meat, Is Inversely Associated with Leukocyte Telomere Length in the Strong Heart Family Study. J Nutr. 2016 Oct;146(10):2013-2018. Epub 2016 Aug 24.

Gosby AK et al. 2010 Design and testing of foods differing in protein to energy ratios. Appetite. 2010 Oct;55(2):367-70. doi: 10.1016/j.appet.2010.06.009.

Gosby AK et al. 2011 Testing protein leverage in lean humans: a randomised controlled experimental study. PLoS One. 2011;6(10):e25929. doi: 10.1371/journal.pone.0025929.

Gosby AK et al. 2014 Protein leverage and energy intake. Obes Rev. 2014 Mar;15(3):183-91. doi: 10.1111/obr.12131.

Halkjær, J et al. 2006 Intake of macronutrients as predictors of 5-y changes in waist Circumference. Am J Clin Nutr 84:789 –97.

Halton TL and Hu FB 2004 The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review. J Am Coll Nutr. 2004 Oct;23(5):373-85

Hodgson, JM et al. 2007 Increased Lean Red Meat Intake Does Not Elevate Markers of Oxidative Stress and Inflammation in Humans. J.Nutr. 137: 363–367.

Holt SH et al. 1997 An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods. Am J Clin Nutr. 1997 Nov;66(5):1264-76.

Houston DK et al. 2017 Protein Intake and Mobility Limitation in Community-Dwelling Older Adults: the Health ABC Study. J Am Geriatr Soc. 2017 Mar 17. doi: 10.1111/jgs.14856.

Hu FB et al. 1999 Dietary protein and risk of ischemic heart disease in women. Am J Clin Nutr. 1999 Aug;70(2):221-7.

Kemp, D and Daly, P 2016 The Ketogenic Kitchen. Gill Books

Kerstetter JE et al. 2011 Dietary protein and skeletal health: a review of recent human research. Curr Opin Lipidol. 2011 Feb;22(1):16-20. doi: 10.1097/MOL.0b013e3283419441.

Kim, I-Y et al. 2014 Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults. Am J Physiol Endocrinol Metab 308: E21–E28, 2015.

Kobayashi, S et al. 2017 Diet with a combination of high protein and high total antioxidant capacity is strongly associated with low prevalence of frailty among old Japanese women: a multicenter cross-sectional study. Nutrition Journal201716:29

Koopman, R et al. 2006 Co-ingestion of protein and leucine stimulates muscle protein synthesis rates to the same extent in young and elderly lean men. Am J Clin Nutr 84:623–32.

Koopman, R et al. 2008 Co-ingestion of leucine with protein does not further augment post-exercise muscle protein synthesis rates in elderly men. British Journal of Nutrition 99, 571–580

Koopman, R, et al. 2009 Ingestion of a protein hydrolysate is accompanied by an accelerated in vivo digestion and absorption rate when compared with its intact protein. Am J Clin Nutr 90:106–15.

Koopman, R, et al. 2009 Dietary Protein Digestion and Absorption Rates and the Subsequent Postprandial Muscle Protein Synthetic Response Do Not Differ between Young and Elderly Men. J. Nutr. 139: 1707–1713,.

Krieger JW et al. 2006 Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression. Am J Clin Nutr. 2006 Feb;83(2):260-74.

Kuipers RS et al. 2010 Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet. Br J Nutr. 104(11):1666-87. doi: 10.1017/S0007114510002679.

Layman DK et al. 2015 Defining meal requirements for protein to optimize metabolic roles of amino acids. Am J Clin Nutr. 2015 Apr 29. pii: ajcn084053.

Lee, JE et al. 2013 Meat intake and cause-specific mortality: a pooled analysis of Asian prospective cohort studies. Am J Clin Nutr 2013;98:1032–41.

Leidy HJ et al. 2010 The influence of higher protein intake and greater eating frequency on appetite control in overweight and obese men. Obesity (Silver Spring). 2010 Sep;18(9):1725-32. doi: 10.1038/oby.2010.45.

Leidy HJ et al. 2015 The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015 Apr 29. pii: ajcn084038.

Leidy HJ et al. 2015 A high-protein breakfast prevents body fat gain, through reductions in daily intake and hunger, in “Breakfast skipping” adolescents. Obesity (Silver Spring). 2015 Sep;23(9):1761-4. doi: 10.1002/oby.21185.

Levine ME et al. 2014 Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population. Cell Metab. 2014 Mar 4;19(3):407-17. doi: 10.1016/j.cmet.2014.02.006.

Lindeberg, S et al.1997 Age relations of cardiovascular risk factors in a traditional Melanesian society: the Kitava Study. Am J Clin Nutr 66:845-52.

Lorenzen, J et al. 2012 The effect of milk proteins on appetite regulation and diet-induced Thermogenesis. European Journal of Clinical Nutrition 66, 622-627.

Macnaughton LS et al. 2016 The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein. doi: 10.14814/phy2.12893 Physiol Rep, 4 (15), 2016, e12893.

Madsen, L t al. 2008 cAMP-dependent Signaling Regulates the Adipogenic Effect of n-6 Polyunsaturated Fatty Acids. J Biol Chem 283:7196.

Mamerow, MM et al. 2014 Dietary Protein Distribution Positively Influences 24-h Muscle Protein Synthesis in Healthy Adults. J. Nutr. 144: 876–880.

Mangano KM et al. 2017 Dietary protein is associated with musculoskeletal health independently of dietary pattern: the Framingham Third Generation Study. Am J Clin Nutr. 2017 Mar;105(3):714-722. doi: 10.3945/ajcn.116.136762.

Martens EA et al. 2015 Maintenance of energy expenditure on high-protein vs. high-carbohydrate diets at a constant body weight may prevent a positive energy balance. Clin Nutr. 2015 Oct;34(5):968-75. doi: 10.1016/j.clnu.2014.10.007.

Moore, DR et al. 2015 Protein Ingestion to Stimulate Myofibrillar Protein Synthesis Requires Greater Relative Protein Intakes in Healthy Older Versus Younger Men. J Gerontol A Biol Sci Med Sci doi:10.1093/gerona/glu103

Moore, J and Westman, EC 2014 Keto Clarity: Your definitive guide to the benefits of a low-carb, high-fat diet. Victory Belt Publishing

Munger, RG et al. 1999 Prospective study of dietary protein intake and risk of hip fracture in postmenopausal women1,2,3 Am J Clin Nutr January 1999 vol. 69 no. 1 147-152

Nieva-Echevarría, B et al. 2017 Effect of the presence of protein on lipolysis and lipid oxidation occurring during in vitro digestion of highly unsaturated oils. DOI: 10.1016/j.foodchem.2017.05.028.

O’Connor LE et al. 2016 Total red meat intake of ≥0.5 servings/d does not negatively influence cardiovascular disease risk factors: a systemically searched meta-analysis of randomized controlled trials. Am J Clin Nutr. 2016 Nov 23. pii: ajcn142521.

Pennings, B, et al. 2011 Whey protein stimulates postprandial muscle protein accretion more effectively than do casein and casein hydrolysate in older men. Am J Clin Nutr 93:997–1005.

Pennings, B et al. 2011 Exercising before protein intake allows for greater use of dietary protein–derived amino acids for de novo muscle protein synthesis in both young and elderly men. Am J Clin Nutr 93:322–31.

Pennings, B et al. 2012 Amino acid absorption and subsequent muscle protein accretion following graded intakes of whey protein in elderly men. Am J Physiol Endocrinol Metab 302: E992–E999, 2012.

Phillips SM et al. 2016 Protein “requirements” beyond the RDA: implications for optimizing health. Appl Physiol Nutr Metab. 2016 Feb 9:1-8.

Phinney SD 2004 Ketogenic diets and physical performance. Nutr Metab (Lond). 2004 Aug 17;1(1):2.

Porter Starr KN et al. 2016 Improved Function With Enhanced Protein Intake per Meal: A Pilot Study of Weight Reduction in Frail, Obese Older Adults. J Gerontol A Biol Sci Med Sci. 2016 Oct;71(10):1369-75. doi: 10.1093/gerona/glv210.

Rafii M et al. Dietary Protein Requirement of Men >65 Years Old Determined by the Indicator Amino Acid Oxidation Technique Is Higher than the Current Estimated Average Requirement. J Nutr. 2016 Mar 9.

Rand WM et al. 2003 Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults. Am J Clin Nutr. 2003 Jan;77(1):109-27.

Raubenheimer, D 2011 Toward a quantitative nutritional ecology: the right-angled mixture triangle. Ecological Monographs 81, Issue 3 August 2011 Pages 407–427 DOI: 10.1890/10-1707.1

Raubenheimer D et al. 2005 Does Bertrand’s rule apply to macronutrients? Proc Biol Sci. 2005 Nov 22;272(1579):2429-34.

Raubenheimer D et al. 2015 Geometry of nutrition in field studies: an illustration using wild primates. Oecologia. 2015 Jan;177(1):223-34. doi: 10.1007/s00442-014-3142-0.

Raubenheimer D et al. 2015 Nutritional ecology of obesity: from humans to companion animals. Br J Nutr. 2015 Jan;113 Suppl:S26-39. doi: 10.1017/S0007114514002323.

Reddy ST, et al 2002 Effect of low-carbohydrate high-protein diets on acid-base balance, stone-forming propensity, and calcium metabolism. Am J Kidney Dis. 40(2):265-74.

Rittig N et al. 2016 Anabolic effects of leucine-rich whey protein, carbohydrate, and soy protein with and without β-hydroxy-β-methylbutyrate (HMB) during fasting-induced catabolism: A human randomized crossover trial. doi:10.1016/j.clnu.2016.05.004.

Roberts, RO et al. 2012 Relative Intake of Macronutrients Impacts Risk of Mild Cognitive Impairment or dementia. J Alzheimers Dis. 32:329.

Simpson SJ et al. 2004 Optimal foraging when regulating intake of multiple nutrients. ANIMAL BEHAVIOUR, 2004, 68, 1299–1311 doi:10.1016/j.anbehav.2004.03.003

Simpson SJ and Raubenheimer D. 2005 Obesity: the protein leverage hypothesis. Obes Rev. 2005 May;6(2):133-42.

Soenen, S et al. 2013 Normal Protein Intake Is Required for Body Weight Loss and Weight Maintenance, and Elevated Protein Intake for Additional Preservation of Resting Energy Expenditure and Fat Free Mass. First published February 27, 2013, doi: 10.3945/​jn.112.167593.

Song, M et al. 2016 Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. See Zoe Harcombe’s demolishing of this junk.

Surdykowski AK et al 2010 . Optimizing bone health in older adults: the importance of dietary protein. Aging health. 6(3):345-357.

Verreijen AM et al. 2017 Effect of a high protein diet and/or resistance exercise on the preservation of fat free mass during weight loss in overweight and obese older adults: a randomized controlled trial. Nutr J. 2017 Feb 6;16(1):10. doi: 10.1186/s12937-017-0229-6.

Weigle, DS et al. 2005 A high-protein diet induces sustained reductions in appetite, ad- libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations. Am J Clin Nutr 82:41– 8.

Westerterp-Plantenga MS et al. 2004 High protein intake sustains weight maintenance after body weight loss in humans. Int J Obes Relat Metab Disord. 2004 Jan;28(1):57-64.

Westman, EC, Phinney, SD and Volek, JS (2010) The New Atkins for a New You. Touchstone.

Willcox, BJ et al 2007 Caloric Restriction, the Traditional Okinawan Diet, and Healthy Aging The Diet of the World’s Longest-Lived People and Its Potential Impact on Morbidity and Life Span. Ann. N.Y. Acad. Sci. 1114: 434–455 (2007). doi: 10.1196/annals.1396.037434.

Wolfe RR et al. 2008 Optimal protein intake in the elderly. Clin Nutr. 2008 Oct;27(5):675-84. doi: 10.1016/j.clnu.2008.06.008. Epub 2008 Sep 25.

Wolfe RR 2012 The role of dietary protein in optimizing muscle mass, function and health outcomes in older individuals. Br J Nutr. 2012 Aug;108 Suppl 2:S88-93. doi: 10.1017/S0007114512002590.

5 thoughts on “Protein – by Kevin Handreck

  • avatar
    February 14, 2018 at 5:33 pm
    Permalink

    “If we worry about it enough, we will probably counter any benefits we might get from choosing the ‘right’ level of protein intake. ”

    Best statement ever. :)

    The only thing I worry about, as I’m T2D, is carbohydrate. If I’m keeping that to an acceptable minimum — basically non-starchy veg. in moderation, no processed foods, no grains or legumes, no added sugars, a little fruit now and again — then the rest will work itself out.

    Reply
    • avatar
      February 14, 2018 at 7:01 pm
      Permalink

      Hi Hugh
      My strategy is similar, although I’m lucky that I don’t have to worry about carbohydrate so much either. If I eat nutritious things, the protein will be what it will be. I did think it was great that Kevin had done all that reading so that we don’t have to!
      Best wishes – Zoe

      Reply
  • avatar
    February 14, 2018 at 1:09 pm
    Permalink

    This analysis is wrong, as Most of these references do no understand or consider Autophagy working in tandem with Apoptosis – Only – Rosedale (TOR advocate) and Mercola are in the ball park.

    We Recycle 70% of our protein requirements “Autophagy”, Dr. Ohsumi (Noble Prize 2016) and the New Science of Autophagy, and the TOR pathway which is pre-mitochondrial. We have little need for proteins as this pathway is highly conserved.

    When we consider that the normal state of man throughout evolution was Starvation, this implies that Fasting is a Normal State, then Eating is a Stress State. We evolved to store fats and proteins ONLY –

    Ref our write up on Autophagy – https://www.70goingon100.com/contributors/ds-mcgerk-14-autophagy-why-we-do-not-need-protein-supplements.html

    Carroll
    https://www.70goingon100.com/index.html

    Reply
    • avatar
      February 14, 2018 at 2:59 pm
      Permalink

      Hi Carroll
      Many thanks for your comment, which is a helpful addition to the debate. Kevin has taken the trouble to review almost 100 papers, written since 1973, for their positions on protein and to share the details of the papers and their outputs with us. I think that many people will find this interesting and useful (and will be keen to look at some papers in more detail). The many different researchers might be wrong, but Kevin can’t be attacked for sharing his research with us!

      Best wishes – Zoe

      Reply
  • avatar
    February 13, 2018 at 2:10 pm
    Permalink

    Seriously? I have Buckley’s chance of figuring out what to do from this. I’m sure it’s great info, but too much for me to absorb.

    Reply

Leave a Reply

Your email address will not be published. Required fields are marked *