OK – the headline is a bit provocative, but we do need to think about the role that fructose is playing in the obesity epidemic. Read the work of Dr Robert Lustig & Dr Richard Johnson to find out more. If you want a quick info graphic to start thinking “sugar” when you see fruit – this may help.
Ask the next person who tells you to eat “Five-a-day” where this slogan comes from. I bet they won’t know.
The pick a number a day campaign (it is not always five in each country) has spread across three continents and tens of countries. It has become the most well known and promoted public health nutritional message ever. You would think, therefore, that it was evidence based and founded upon robust scientific knowledge. You would be wrong.
Five-a-day was invented in 1991, in California, at a meeting of the (American) National Cancer Institute (NCI) and the Produce for Better Health Foundation.
The NCI has since trademarked the term five-a-day. The Produce for Better Health Foundation reads like the who’s who of the fruit and vegetable producer, packager and logistics world – companies who all stood to gain if the world started eating more fruit and veg.
Given the connection with the NCI, the programme was probably intended to help cancer in some way (it was never intended to help obesity). There was no evidence that it would do anything positive for cancer at the time. Attempts have been made to post rationalise it since, but these have failed.
The most recent study was published in April 2010, in the Journal of the National Cancer Institute (Ref 1). The study involved 142,605 men and 335,873 women for the period 1992-2000. This review of almost half a million people found that eating five portions of fruit and vegetables a day had little effect on cancer risk and the very small difference observed could be explained by other factors. The study also grouped participants into five categories from the lowest intake of fruits and vegetables (0 to 226 grams a day) to the highest intake (more than 647 grams a day). Significantly, the cancer risk did not vary between the five groups.
In November 2010, the UK part of the EPIC study published their findings in the British Journal of Cancer (Ref 2). Professor Tim Key concluded that: “The possibility that fruit and vegetables may help to reduce the risk of cancer has been studied for over 30 years, but no protective effects have been firmly established.”
Even in the absence of evidence – and notwithstanding the potential harm from the 5.6 billion pounds of pesticides used worldwide each year (Ref 3) – is there still some benefit for consuming pick-a-number-a-day?
This is where we must distinguish between fruit and veg – they should never appear together in the same sentence. Some vegetables – especially dark green varieties like spinach, kale and broccoli – can be very useful for vitamins and minerals. These need to be served with butter (as granny knows), so that the fat soluble vitamins (A, D, E and K) can be optimised by the body. We still need animal foods (meat, fish, eggs, dairy) for retinol (the correct form of vitamin A), B12 and K2, but certain vegetables can be helpful.
Fruit, on the other hand is unhelpful. Fructose (fruit sugar) is called the fattening carbohydrate and this has been known, incredibly, since 1916, but dieticians are not the most up-to-date bunch. Fructose is implicated in non-alcoholic-fatty-liver-disease and Alzheimer’s (now being called Diabetes Type 3). Fructose goes straight to the liver to be metabolised, where it is nicely turned to fat.
Fruit is not even nutritionally worth its fattening properties – it is good for 1 out of 13 vitamins (vitamin C – vegetables are just as good a source of vitamin C, if not better) – meat, fish and eggs clean up on the other 12. Fruit is good for 1 out of 16 minerals (potassium) – rarely a mineral we are deficient in – animal foods, again, are abundant sources of all essential minerals.
Working exclusively in the field of obesity, as I do, I am horrified by well intentioned parents trying to get five-fruit-a-day into their children (fruit being an easier ‘sell’ than veg) when this is merely fuelling the obesity epidemic.
We need to know at this point that sugar (the stuff we put in our tea/coffee and cakes) is made up of one molecule of glucose and one molecule of fructose. The key change in our diet during the period in which obesity has gone up so dramatically is not just our consumption of sugar – but quite specifically the combination of fructose and glucose. Fruit varies in its balance of glucose and fructose, but it’s the same sugar to the body – fruit just has some nutrition and sucrose none.
The combined potency of fructose and glucose is as follows – as the fructose proportion heads to the liver for its metabolism it has little impact on blood glucose levels. The glucose proportion performs this role and stimulates the pancreas to provide insulin. Hence we have triglycerides being formed, courtesy of the fructose, and they are able to be stored, thanks to the glucose causing insulin to be provided. Food manufacturers may like to argue that all sugar is equal – but, when it comes to enabling fat to be stored, the glucose/fructose combinations are more equal than others. They are particularly fattening.
Fresh fruit is way too high in sugar for anyone concerned about their weight. As for dried fruit and fruit juice – don’t even go there.
Don’t take my word for it. As Dr Robert Lustig says – you wouldn’t dream of giving your child beer or cola, but fruit juice is metabolised by the body in the same way. Or, as Gary Taubes says, “If you are overweight, fruit is not your friend.”
If only public health officials had promoted the 5 most nutritious foods on the planet, we may not have epidemics of obesity and ill health. An optimally nutritious five-a-day would be meat (ideally liver); fish (ideally sardines); eggs; sunflower seeds and spinach.
However, this was never about optimal health – it was a marketing slogan to increase profits of fruit and veg companies. Rarely is health ever prioritised above big business.
Ref 1: Paolo Boffetta et al, “Fruit and vegetable intake and overall cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC)”, Journal of the National Cancer Institute, (April 2010). (See reference 278 The Obesity Epidemic)
Ref 2: http://www.nature.com/bjc/journal/vaop/ncurrent/full/6606032a.html
Ref 3: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2946087/