From Meta Science News:

Cell: Nutrition is personal. Identical foods produce “healthy” and “unhealthy” responses in different individuals. Biology • Health • November 19th, 2015 • Meta5 In today’s issue of Cell, two groups led by Eran Elinav and Eran Segal have presented a stunning paper providing startling new insight into the personal nature of nutrition. The Israeli research teams have demonstrated that there exists a high degree of variability in the responses of different individuals to identical meals, and through the elegant application of machine learning, they have provided insight into the diverse factors underlying this variability.

The existence of human biodiversity shouldn’t be such a startling new insight, but I guess it is.

It ought to be obvious by now that different people flourish or decay on different diets.

And yet we constantly read of nutrition studies that assume that their goal should be to find the best diet for everybody rather than to find diets that work better for some people.

Our vast amount of biographical knowledge of celebrities attests to important degrees of diversity in optimal diet. For example, the Duke of Wellington (1769-1852) was a model of good health throughout his long, successful life, at a time when other aristocrats tended to get gout from overeating. The Duke was notorious in British society for eating what today we would consider a high carb diet of a huge amount of rice — he boasted of eating very little besides rice during three years service in India, and brought his taste for rice with him for the rest of his life.

A lot of people today flourish on a high carb diet, as Wellington did during his long life. But not everybody does. I tried it once and put on weight immediately.

The behavioral implication of this is that you ought to try different diets for yourself (especially ones that seem to work for your blood relatives) and see which ones work for you.

This advice doesn’t sound terribly unreasonable, but for some reason, however, taking into account the impact of genetic diversity strikes a lot of people these days as not Science.

Wellington lived in a time and place that took pride in eccentrics, especially if they were dukes.

Now that I think about it, perhaps our modern assumption that Science means that scientists will eventually discover the one best diet for everybody grows out of the rejection of the theory of human biodiversity that goes back to Hippocrates’ and Galen’s idea of four humors (“sanguine”, “choleric”, “melancholic” and “phlegmatic”), which vary in balance among individual leading to different temperaments.

The English around Shakespeare’s time were particularly taken with the Greek theory of the different humors, and they developed a nationalistic ideology of psychology and literature that asserted that English liberty allowed individuals to better express their humors in England than anywhere else. In turn, this led to English literature being more “humorous” than other literature in the sense that their plays and novels were full of amusing eccentrics. Or at least that’s how the English felt about why they were more humorous than, say, the Germans (or at the least English found themselves more humorous than they found the Germans).

Anyway, all this earth, wind, fire, and air stuff got dumped eventually as unscientific. But perhaps we threw out the baby of human biodiversity along with the bathwater of the humors?