Obesity has become the second leading cause of death globally after smoking. Obesity and overweight is a global health problem that increases the risk of many other diseases such as diabetes, hypertension, cardiovascular diseases and fatty liver disease. A body mass index over 25 is considered overweight and over 30 is obese. According to the World Health Organization 1.9 billion adults worldwide were overweight in 2016, with 650 million obese.
Bacillus natto can reach our intestine in living condition because they can survive gastric acids. It produces a variety of antibiotics and other antibacterial compounds. Researchers from the Qingdao University, China, tested the effect of Bacillus natto intake on rats that were exposed to a high fat diet [1]. They found that Bacillus natto significantly reduced body fat and reduced liver weight. In addition, serum triglyceride and cholesterol levels were reduced. Other indicators of obesity were also improved. More specifically they found that Bacillus natto reduced fatty acid production by regulating the production of Pparα and Srebp-1c. Bacillus natto increased the production of Pparα, an regulator that results in fat breakdown, and inhibited the production of Srebp-1c, a regulator that increases the accumulation of fat.
The researchers also determined the effects of Bacillus natto on the composition of the gut flora. They found that Bacillus natto increased the ratio of Bacteroidetes to Firmicutes. Maybe you never heart about these bacteria, but they are important to maintain gut health, maybe more important than other so-called friendly bacteria, such as Lactobacillus or Bifidobacterium. Bacteroidetes have a very broad metabolic potential and are regarded as one of the most stable part of gastrointestinal micro-flora. When the gut microbiota of obese and lean people are compared, obesity is associated with a higher amount of Firmicutes and a lower amount of Bacteroidetes.
Another study also evaluated the anti-obesity effect of Bacillus natto in obese rats and analyzed the changes of the expression levels of genes and proteins related to glycolipid metabolism [2]. This study also confirmed the potential for using Bacillus natto to prevent and treat obesity. More specifically, thet found that Bacillus natto significantly reduced body weight, epididymis fat weight, total cholesterol, triglyceride, low-density lipoprotein while increasing the level of high-density lipoprotein. Bacillus natto also improved liver injury by reducing alanine aminotransferase and aspartate transaminase levels.
The results of these studies on rats looks very promising. However, more studies on humans have to conducted to confirm the effects of Bacillus natto intake by humans.
[1] Pinggui Wang et al, Bacillus natto regulates gut microbiota and adipose tissue accumulation in a high-fat diet mouse model of obesity. J Funct Foods. 2020;68:103923.
[2] Ruiyue Sun et al, Bacillus natto ameliorates obesity by regulating PI3K/AKT pathways in rats. Biochem Biophys Res Commun. 2022 May 7;603:160-166.