Centenarians and microbiota

Centenarians are people older than 100 years (this is what we call longevity). When they are healthy, they are good examples of successful ageing. Living over 100 is more common in some parts of the world than others. The highest density of centenarians is present in Japan and Southern Europe, People aged between 100 and 104 have reduced microbial diversity and compromised stability of microbiota. They also got specific age-related microbes, higher levels of opportunistic pathogens and lower levels of beneficial butyrate producing bacteria. But healthy people with great longevity reaching 104-109 are different than normal centenarians. They have the same bacteria, but the proportion is different. They got more Bifidobacterium, Akkermansia and Christensenellaceae. Longevity is indeed associated with microbiota changes, and further studies of the specific bacteria linked with longevity can help us to find strategies that use diet to promote a healthy microbiota and a healthy ageing.

Dietary habits can play a role on the development and the severity of the chronic diseases such as diabetes type 2, heart disease and certain types of cancer. You probably know that nutrition has a role in preventing diseases and promoting health. Caloric intake and timing of eating food, and well as the nutrients provided by the food consumed, all of these have a role in improving health and even longevity.

For example, reducing food but preventing malnutrition improves ageing (first research on this subject, made in 1935, found that food restriction avoiding malnutrition resulted in higher maximum lifespan in rats). Since then experiments followed on nematode worms, fruit flies, fish, mice up to non-human primates and humans, and all of them underlined that the quality of diet and the caloric intake plays a role in improving health and longevity. Basically a caloric restriction between 10 to 50% improves the lifespan in most of the cases, however there is a small number of cases where a higher percentage of the calorie restriction will not increase the lifespan, an 40-50% is too much for these subjects.

Microbiota-wise, longevity is characterized by a stable core microbiota. The core microbiota shrinks with age, and the subdominant bacteria increase in abundance. For Chinese, Japanese and Italian elderly groups the bacteria that are enriched include Clostridium, Ruminococcaceae, Akkermansia and Christensenellaceae. These bacteria are linked to gut body mass index, immunomodulation and healthy homeostasis. In conclusion, there are several factors of one's diet to influence longevity. Caloric restriction is one of them, having a major potential to increase life expectancy.

General knowledge on the relationship between gut microbiota and longevity can be used to improve the lifespan of the elderly through diet and modulation of their microbiota.