Heart Disease

Heart healthy diets

A recent paper titled “Popular dietary patterns: alignment with American Heart Association 2021 dietary guidance: A scientific statement from the American Heart Association” has received a great deal of media attention. Professor Christopher Gardner was the lead author of the paper. We have covered his work in previous Monday notes.

In 2021, the American Heart Association (AHA) issued a scientific statement setting out 10 key principles of a heart healthy diet. This Gardner et al paper simply reviewed 10 diets against these 10 key principles. The 10 diets were: DASH; Mediterranean style; pescetarian; vegetarian; vegan; low fat; very low fat; low carbohydrate; Paleo and very low carbohydrate.

The article emphasised that we consume diets, rather than nutrients, and that the historical focus on nutrients needs to be shifted away from. This was positive. Consistent with the approach of the Dietary Guidelines for Americans, the article referenced Acceptable Macronutrient Distribution Ranges, which were developed by the Institute of Medicine and have been used since 2005. The article didn't challenge these ranges. The recommendation that carbohydrate should form 45-65% of one's energy intake should have been the first challenge!

The AHA assumes that animal foods are bad and plant foods are good, fat is bad, and carbs are good etc. Inevitably, therefore, plant-based diets (DASH, Mediterranean, pescetarian, vegetarian and vegan) scored well and low-carb, keto, Paleo diets scored badly.

By using this as a base, the Gardner et al study replicated the erroneous assumptions. The most striking part of the paper was a very visual red/green coloured table where the plant-based diets scored lots of greens "fully meets AHA recommendations" and the animal-food based diets scored lots of reds "does not meet AHA recommendations." The recommendations were wrong, not the diets.

I repeated the exercise with the following approach 1) know the nutrients that we must consume 2) know where we find those nutrients 3) judge diets according to the essential nutrients that they provide. As the essential nutrients are optimally found (and in the right form) in animal-foods, this turned the table red and green the other way round.

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