Obesity: beware of B vitamin deficiency!

Although we need only very small quantities, vitamins are no less essential to our health—if we do not get enough vitamin C, for example, we can develop scurvy, a disease from which many sailors died when a lemon would have been enough to save them. To a lesser extent, cognitive disorders, numbness or a persistent state of fatigue can also be signs of a vitamin B deficiency. Moreover, the etymology of the word reveals something of its “vital function”: “vitamin” comes from the Latin “vita,” meaning life.

The B7 engine

Among the many vitamins essential for our body to function properly are the B vitamins, including the famous vitamin B7, also called biotin (sidenote: Biotin Called vitamin B7, or B8 in certain countries. This vitamin plays a key role in the metabolism of carbohydrates, lipids and amino acids. It is also involved in the biosynthesis of other vitamins (B9 and B12). Many foods are good sources of biotin (whole grains, eggs, milk, nuts, etc.). This vitamin is also synthesized by the bacteria in gut flora. Biotin_NIH National Cancer Institut ) . One of our main sources of biotin is food, but that’s not all! The bacteria in gut microbiota also produce it... or not, as the case may be. And this has consequences for our health, especially in the case of obesity.

The vicious circle of obesity

A team of researchers has just shown that the gut bacteria that produce and transport biotin are absent in severely obese patients (BMI (sidenote: Body Mass Index (BMI) Body Mass Index (BMI) assesses the corpulence of an individual by estimating the body fat mass calculated by a ratio between weight ((kg) and height squared (m2). https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm https://www.euro.who.int/en/health-topics/disease-prevention/nutrition/a-healthy-lifestyle/body-mass-index-bmi ) > 35). Their obese host is thus deprived of this additional non-dietary source, despite actually needing more than the average person (vitamin B being necessary for well-balanced adipose tissue). Experiments in animals show that the western diet (sidenote: Western diet Diet rich in processed foods, refined sugar, salt, saturated fats (red meats) and trans fats (pastries) Zinöcker MK, Lindseth IA. The Western Diet-Microbiome-Host Interaction and Its Role in Metabolic Disease. Nutrients. 2018 Mar 17;10(3):365.  ) , well known for promoting obesity, reduces both the quantity of biotin-producing gut bacteria and the circulating levels of this vitamin in serum. Also, paradoxically, the gut inflammation observed in obese patients limits the absorption of biotin supplied by the diet.

In cases of severe obesity, a vicious circle is thus set in motion, since gut dysbiosis is believed to aggravate inflammation (and obesity) as well as tissue biotin deficiency.

Boosting biotin production

How can we break this vicious circle? Weight-loss surgery (bariatric surgery), which improves metabolism and inflammation, stimulates growth of biotin-producing bacteria, resulting in an increase—at least during the first year—in the level of biotin circulating in the body. Another approach involves supplementing with prebiotics (fructo-oligosaccharide type fibers) and biotin. This has been tested in mice fed a high-fat diet, and was found to improve the diversity of gut microbiota and boost bacterial production of biotin and other B vitamins, while limiting weight gain and deterioration of blood sugar levels.

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