Image: Getty. By Bianca Nogrady.
Even if we all ate the same meal, everyone would metabolise it differently, according to a new study that suggests that there is no such thing as one-size-fits-all dietary advice.
Rather diets should be tailored to an individual’s gut microbiome, or combination of gut bacteria, Israeli scientists said. The glycaemic index is used by doctors and nutritionists to develop healthy diets based on how different foods affect glucose levels in the blood.
But the study, published today in Cell, shows different people can have a very different glycaemic response to a food.
“If my and your response to the same food are opposite then by definition a similar diet cannot be effective for both of us,” said co-author Dr Elan Elinav, from the Immunology Department at the Weizmann Institute of Science.
The team found that an individual’s gut bacteria was a key factor influencing whether a food delivers a long, slow rise in blood sugar, or a short, sharp spike. In the first part of the study, 800 volunteers — some healthy, some with pre-diabetes — were hooked up with devices that continually monitored their blood sugar levels, and equipped with an app to record their every move and meal. Over one week, this revealed dramatic differences in each person’s blood sugar response to different foods.
“We would expect that in average people, their blood sugar would spike more on ice-cream than rice,” Dr Elinav said.
“What we found in this really large cohort is that some people did exactly that but others did exactly the opposite.
“They were not responsive to ice-cream at all, and actually close to 70 per cent of the study population did not even spike on ice-cream.”
At the same time, researchers took blood and sampled each individual’s gut bacteria, looking not only at the makeup of their gut bacteria but also the functional profile of the microbiome.
Algorithm predicts individual’s glycaemic response.
Using all this data, the group developed an algorithm to predict an individual’s glycaemic response to a food, based on factors such as their microbiome, daily activity, blood parameters such as cholesterol, and food content.