The universal idea of what a healthy diet is could soon be a thing of the past. Researchers from the Weizmann Institute of Science in Israel discovered that people fed with the same food had different health responses. This means what's healthy for one is not necessarily healthy for another.
For years, doctors and nutritionists have used the glycemic index (GI), a standard that ranks food according to how it affects blood glucose levels, to formulate healthy diets for patients. The researchers pointed out, however, that individuals showing different blood glucose responses to food indicated a gap in the use of GI grading system.
In the study, called the Personalized Nutrition Project, the researchers focused on the effect of various foods in the blood glucose levels of 800 participants for a week, analyzing the results for a total of 46,898 meals. They found that the participants varied in their response to the same food, but their individual responses were consistent from day to day.
"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," study author Eran Segal from Weizmann's Department of Computer Science and Applied Math said in a press release.
In one example, a woman suffering from pre-diabetes and obesity ate tomatoes as part of a "healthy diet," only to find out that tomatoes actually caused a spike in her blood glucose.
The researchers attributed the participants' varying responses to food to the uniqueness of their gut bacteria.
"In contrast to our current practices, tailoring diets to the individual may allow us to utilize nutrition as means of controlling elevated blood sugar levels and its associated medical conditions," Eran Elinav, study coauthor from Weizmann's Department of Immunology, said in the press release.
To enable them to formulate personalized nutrition recommendations, the researchers developed an algorithm that predicted an individual's blood glucose response to certain kinds of food, taking into consideration the person's lifestyle, gut bacteria and medical background. They tested the accuracy of the algorithm in a follow-up study involving 100 volunteers and found that it correctly predicted the volunteers' blood glucose responses to certain kinds of food.
"After seeing this data, I think about the possibility that maybe we're really conceptually wrong in our thinking about the obesity and diabetes epidemic," Segal said. "The intuition of people is that we know how to treat these conditions, and it's just that people are not listening and are eating out of control - but maybe people are actually compliant but in many cases we were giving them wrong advice."
The study was published in the Nov. 19 issue of the journal Cell. Watch the following video animation for more information.