2. The scientific evidence for dietary claims

Dietary information for a healthy life should be based on robust scientific evidence. Much of the world relies on the US dietary guidelines - but can we rely on them?

A report published by the BMJ in 2015 and 2016 highlights a number of issues

Feature Nutrition

The scientific report guiding the US dietary guidelines: is it scientific?

BMJ 2015; 351 doi: https://doi.org/10.1136/bmj.h4962 (Published 23 September 2015) Cite this as: BMJ 2015;351:h4962

Corrections

The scientific report guiding the US dietary guidelines: is it scientific?

BMJ 2016; 355 doi: https://doi.org/10.1136/bmj.i6061 (Published 02 December 2016) Cite this as: BMJ 2016;355:i6061

This report highlights the risk of bias and conflict of interest.

"For example, a bias towards the longstanding view that saturated fats are harmful can be seen in the report’s designation of them, together with sugar, as a new category it calls “empty calories.”2 The report repeatedly mentions the need to reduce “sugar and solid fats,” because, “both provide calories, but few or no nutrients.”2 Yet this pairing is unsupported by nutrition science. Unlike sugar, saturated fats are mostly consumed as an inherent part of foods such as eggs, meat, and dairy, which together contain nearly all of the vitamins and minerals needed for good health. "

"Much has been written about how industries try to influence nutrition policy, so it is surprising that unlike authors in most major medical journals, guideline committee members are not required to list their potential conflicts of interest. A cursory investigation shows several such possible conflicts: one member has received research funding from the California Walnut Commission61 and the Tree Nut Council,62 as well as vegetable oil giants Bunge and Unilever.63 64 Another has received more than $10 000 (£6400; €8800) from Lluminari, which produces health related multimedia content for General Mills, PepsiCo, Stonyfield Farm, Newman’s Own, and “other companies.”65 And for the first time, the committee chair comes not from a university but from industry: Barbara Millen is president of Millennium Prevention, a company based in Westwood, MA, that sells web based platforms and mobile applications for self health monitoring. While there is no evidence that these potential conflicts of interest influenced the committee members, the report recommends a high consumption of vegetable oils and nuts as well as use of self monitoring technologies in programs for weight management."

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So where should we look for the scientific evidence?

"The Women’s Health Initiative (WHI), was the largest nutrition trial in history...Nearly 49 000 women followed a diet low in fat and high in fruits, vegetables, and grains for an average of seven years, at the end of which investigators found no significant advantage of this diet for weight loss, diabetes, heart disease, or cancer of any kind"

Health depends on eating a broad and balanced diet ( and not too much of it ), getting plenty of exercise every day and a good night's sleep every night.

What constitutes a broad and balance diet? A good range of fresh meat, fish, eggs, cheese,  fruit and vegetables and grains / starches. Not too much of each.

Avoid too much highly processed foods.

Avoid trans fats -synthetic fat products.

And if the Hay diet helps you achieve this then it is an excellent diet to follow.