Friday, 9 March 2018

Here's why the food pyramid is wrong

[from RTE Brainstorm]


Department of Biological Sciences

Opinion: we rely on the food pyramid to tell us what food to eat and how often, yet such dietary guidelines are not quite as straightforward as they appear

When it comes to nutrition, we rely on dietary guidelines provided often in a form of a pyramid. The current food pyramid in Ireland was published in December 2016. When such a pyramid is projected on a piece of paper (or a screen) it looks like a triangle with several shelves. The lower the shelf a food occupies, the healthier this food is and therefore the more often it must be consumed. Therefore, we can get a general guideline on what to eat and how often by looking at the pyramid. This is widely available and is also taught in all secondary schools around the country.



Alas it is wrong! And this is why…

The concept of food pyramids stemmed from the pioneering Seven Countries Study that was inspired by Ancel Keys in the 1950s and was carried out in the 1960s, 1970s and 1980s. Keys' research collaborators around the world screened the diet, the levels of serum cholesterol and the incidents of heart disease in different populations around the world. They found a clear linear relationship between serum cholesterol and heart disease in countries like US, Finland and Netherlands. The higher the cholesterol in the blood, the more fatal heart incidents were observed.

However, no such correlation was found in countries like Greece, Italy and Japan, i.e. blood cholesterol did not have an impact on heart-related deaths. There observations were used in order to design the Mediterranean Diet Pyramid by combing all the dietary habits in these countries. The message of this pyramid is that this diet has a cardioprotective effect and cholesterol does not cause heart diseases. Here's the current version of the Mediterranean diet pyramid

Comparing the two pyramids, we can observe that:
(1) in the Food Pyramid, both fats and oils and meat and fish are grouped together. From a food chemistry and nutritional point of view, these are major scientific mistakes.
(2) the cardioprotective properties of fats differ dramatically between processed fats (e.g. crisps) and natural fats (e.g. nuts, dried fruits, olive oil). The information that passes to the public is that all fats are the same, but this is not the case. We should communicate that some fats actually have strong cardioprotective properties (i.e. all polar lipids in wine, fish, vegetable oils, olives etc).
(3) meat and fish have distinctive nutritional values in terms of cardioprotection so it is a major oversight to group these foods. Fish (any fish) has strong anti-inflammatory properties and this is why fish have their own shelf in the Mediterranean Diet Pyramid.
We suggest that the Irish Food Pyramid should be edited as soon as possible to convey the correct dietary message to the public
In our research, we study the impact of these foods on biomarkers related to the onset of Cardiovascular Diseases (CVDs) by comparing how lipids of different foods (of animal, marine or plant origin) affect human platelets aggregation and the formation of thrombus in our arteries. We have found that olives, olive oil, marine food (i.e. salmon, sea bass, trout etc), red wine and fermented dairy products such as kefir, yoghurts and cheese have strong cardioprotective bioactivities.

Taking into account this data and the Mediterranean Diet Pyramid, we would suggest that the Irish Food Pyramid should be edited as soon as possible to convey the correct dietary message to the public. This would include
(1) do not group fish, meat and poultry together and move fish to a lower shelf of the pyramid,
(2) nuts and olive oil should be moved to the same group as fruits and vegetables
(3) the moderate amount of one to two glasses of red wine per day could be encouraged in line with the Mediterranean Diet Pyramid (see glass of red wine on the left of that pyramid).
While these two trends should cause immediate concern, they should also push us to publish better dietary guidelines for the public
On top of these recommendations, the inclusion of some encouragement or recommendation of physical activity and sharing meals with others (see bottom layer of the Mediterranean Diet Pyramid) should be considered. The latest Childfood Obesity Surveillance Initiative (COSI) report shows that around one in five children today in Ireland are overweight or obese. Also, the number one killer disease in Ireland today is CVDs, killing about 10,000 per annum.
While these two trends should cause immediate concern, they should also push us to publish better dietary guidelines for the public. In this way, we can make sure that we put science in the service of the public (and not only to promote our careers) for the true benefit of our children, students and society.

The views expressed here are those of the author and do not represent or reflect the views of RTÉ
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