DASH vs American diet

Executive Summary

* This week's note looks at the DASH diet trial, which was conducted in the 1990s. DASH stands for Dietary Approaches to Stop Hypertension. It's the diet claimed to reduce blood pressure.

* The original trial randomised 459 adults to the DASH diet, a diet high in fruits and vegetables (F/V diet) or the standard American diet for 8 weeks.

* A paper has recently been published, which revisited the trial to look at the estimated 10-year risk of atherosclerotic cardiovascular disease (ASCVD) between the three diets.

* There were no differences between the F/V and DASH diets. This means that the American diet was bad rather than the DASH diet good.

* All three diets lowered blood pressure – by tiny or small amounts. The DASH diet also lowered total and HDL cholesterol. I explain why.

* The study claimed that the F/V and DASH diets reduced 10-year risk of ASCVD. This turned out only to be the case for women, black people and those who weren't obese.

* The risk reduction was attributed to the reduction in blood pressure. I explain why this happened and how blood pressure could have been reduced far quicker and more effectively.