A diet high in sugar and fat leads to an imbalance of the intestinal microbiota, whose role is nevertheless fundamental in the prevention of diseases such as obesity or diabetes.
- In France, 8 million people are obese, which represents 17% of the adult population.
- Nearly 4 million people were identified as diabetic by health insurance in 2019.
- 22.5% of men and 18.5% of women have a metabolic syndrome in France, the over 50s being the most affected, according to a 2004 study coordinated by the WHO.
We know that the excess of sugar and fat in our western diet is bad for our health. It contributes to the development of certain diseases, such as obesity, type 2 diabetes or metabolic syndrome (a set of disorders due to excess fat: weight gain, insulin resistance, glucose intolerance, etc.). But in addition to that, it unbalances our intestinal microbiota, this ecosystem of more than 10,000 billion bacteria, fungi and yeasts, which populates our intestines, helps us to digest and protect us against the invasion of pathogenic substances. This was brought to light by researchers at Columbia University in a recent study.
Mice sick in four weeks from sugar
They observed the effects of a diet very high in sugar and fat on the gut microbiota of mice. Result: the rodents developed a metabolic syndrome after only four weeks. Their microbiota came out strongly altered, with a significant reduction in the number of filamentous bacteria, eliminated by the sugar. However, these bacteria have an important role in the microbiota: they protect the intestine from certain diseases by regulating the absorption of lipids, present in the fats that we eat, thanks to immune cells called Th17.
The real protection is that of the microbiota
Conversely, with a diet lower in sugar and fat, the mice retain their Th17 cells and remain fully protected against the development of obesity or pre-diabetes, by eating the same amount of calories.
The researchers insist that while diet matters a lot, the real protection comes from Th17 cells induced by filamentous bacteria in the microbiota. When the mice were deprived of it, removing the sugar did not have the expected benefits. Under these conditions for humans, prescribing probiotics in addition to a diet could be necessary.