'Healthy' foods differ by individual

http://www.eurekalert.org/pub_releases/2015-11/cp-fd111215.php

Public Release: 19-Nov-2015
'Healthy' foods differ by individual
Cell Press

Ever wonder why that diet didn't work? An Israeli study tracking the blood sugar levels of 800 people over a week suggests that even if we all ate the same meal, how it's metabolized would differ from one person to another. The findings, published November 19 in Cell, demonstrate the power of personalized nutrition in helping people identify which foods can help or hinder their health goals.

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As expected, age and body mass index (BMI) were found to be associated with blood glucose levels after meals. However, the data also revealed that different people show vastly different responses to the same food, even though their individual responses did not change from one day to another.

"Most dietary recommendations that one can think of are based on one of these grading systems; however, what people didn't highlight, or maybe they didn't fully appreciate, is that there are profound differences between individuals--in some cases, individuals have opposite response to one another, and this is really a big hole in the literature," says Segal, of Weizmann's Department of Computer Science and Applied Math.

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The individualized feedback yielded many surprises. In one case, a middle-aged woman with obesity and pre-diabetes, who had tried and failed to see results with a range of diets over her life, learned that her "healthy" eating habits may have actually been contributing to the problem. Her blood sugar levels spiked after eating tomatoes, which she ate multiple times over the course of the week of the study.

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To understand why such vast differences exist between people, the researchers conducted microbiome analyses on stool samples collected from each study participant. Growing evidence suggests gut bacteria are linked to obesity, glucose intolerance, and diabetes, and the study demonstrates that specific microbes indeed correlate with how much blood sugar rises post-meal. By conducting personalized dietary interventions among 26 additional study participants, the researchers were able to reduce post-meal blood sugar levels and alter gut microbiota. Interestingly, although the diets were personalized and thus greatly different across participants, several of the gut microbiota alterations were consistent across participants.

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