Many people cannot digest milk well – but it is precisely this food that could protect against type 2 diabetes. A research team reports on this unusual connection between food intolerance and a health-promoting effect in the journal “Nature Metabolism”. In lactose-intolerant people, the risk of type 2 diabetes is significantly reduced if they regularly consume dairy products. The confirmation However, a causal connection is still pending.
Lactose intolerance is widespread
In Asia the majority of people are lactose intolerant; in Europe it is up to 40 percent of the population. Some people don’t even notice that the lactase enzyme, which breaks down milk sugar in the intestine, declines after infancy, explains Robert Wagner from the German Diabetes Center (DDZ), who was not involved in the study. Such so-called lactase non-persistent (LNP) people often still consumed milk and tolerated possible symptoms such as flatulence or stomach pain.
In general, lactose-intolerant people can often consume a certain amount of lactose, says Lonneke Janssen Duijghuijsen from Wageningen University (Netherlands). “Research has shown that many people who do not have lactase can still consume up to twelve grams of lactose per day – which is equivalent to the amount in a large glass of milk – without suffering from intolerance symptoms.”
Lactose has a positive effect on metabolism
For such people, the study shows that milk consumption is statistically associated with a lower incidence of diabetes, says Wagner. In addition, LNP people with higher milk consumption also have a lower body mass index (BMI) on average. In lactose-tolerant people, however, consuming milk can actually have the opposite effect – weight gain, increasing the risk of diabetes – because milk is very nutritious.
In lactose-tolerant people, the milk sugar is digested and absorbed in the small intestine, meaning it is no longer available to the beneficial bacteria in the large intestine. It is obvious that in lactose-intolerant people, milk consumption feeds certain bacteria in the colon with milk sugar (lactose) and as a result they grow better, explains Wagner. They then produced increased amounts of substances that have a positive effect on metabolism and can thus protect against type 2 diabetes. However, there is still no reliable evidence for this mechanism.
Janssen Duijghuijsen also says that the suspected connection is plausible, but must be proven causally. Other influencing factors are also conceivable. Nutritional recommendations cannot initially be derived from the results.
The risk of diabetes is reduced by 30%
The research team led by Qibin Qi from the Albert Einstein College of Medicine in New York recorded for almost 13,000 participants in the so-called Hispanic Community Health Study/Study of Latinos (HCHS/SOL) in the USA whether they were lactose tolerant or intolerant and how often they consumed milk. Data on the gut microbiome and blood values of these men and women as well as information from a British database were also included. Socioeconomic, demographic and behavioral factors were eliminated.
According to the evaluation, higher milk consumption in lactose-intolerant people, but not in lactose-tolerant people, is associated with a reduced risk of type 2 diabetes by around 30 percent. Intestinal microbiome and certain blood values were changed. For example, there were more Bifidobacterium species – important protective germs in the intestine.
The study shows the interesting effect that foods that we supposedly cannot tolerate could even have a protective effect, says Wagner. There may be other such connections. “Flat, intestinal noises or similar symptoms that are familiar from intolerances can, under certain circumstances, also be a sign of health-promoting processes.”