AsianScientist (Jul. 22, 2013) – Scientists in China have found that restricting calorie intake promotes the growth of gut bacteria associated with an increased lifespan in mice. This finding suggests that caloric restriction might have beneficial health effects by promoting a healthy gut microenvironment.
Caloric restriction through reduced food intake is known to increase lifespan in a range of model organisms. The gut microbiota is increasingly recognized for its role in host health and disease, and its composition is shaped mainly by the diet.
A team of scientists led by Prof. Liping Zhao, Professor of Microbiology at the Shanghai Jiao Tong University in China, put mice on a life-long calorie-restricted diet and documented structural changes in their gut microbiota over time.
Publishing in the journal Nature Communications, the team reports that specific bacteria correlate positively with lifespan and are enriched by caloric restriction. Conversely, the calorie-restricted diet reduced the abundance of bacteria that correlate negatively with lifespan.
“Restriction of dietary intake by about 30 percent can significantly change the composition of the gut microbiota. Caloric restriction promoted some bacteria which are beneficial, like Lactobacillus, and reduced bacteria which are detrimental, which are opportunistic pathogens,” said Prof. Zhao.
The changes caused by restricting calories were associated with reduced serum levels of lipopolysaccharide (LPS)-binding protein, a marker often associated with inflammation. This means that reduced inflammation caused by antigens from gut bacteria might be one of the health benefits transmitted by caloric restriction.
“LPS binding protein is produced by the liver and is used by the host to bind LPS, which is an endotoxin produced by gut bacteria. If you change the composition of the gut microbiota to a healthier state, that means the endotoxin producers would be reduced and beneficial bacteria would increase, and less endotoxin would get into the bloodstream,” he explained.
Turning to yoghurt for a longer life?
Although the genus Lactobacillus was found to be increased in the guts of mice fed a calorie-restricted diet, Prof. Zhao cautions against actively consuming Lactobacillus-containing yoghurt for a longer life because it is still unknown which Lactobacillus strains are beneficial.
Lactobacillus is a genus of bacteria with many different species, each of which comprise multiple strains. Different strains within the same species can have up to 30 percent genetic differences between them. In comparison, humans and mice only differ genetically by up to 10 percent, which means that the differences between bacterial strains could be much larger than between humans and mice.
Only certain Lactobacillus strains are beneficial, therefore identifying precisely which strains these are is an important next step for Prof. Zhao and his team. In addition, further studies are needed to clarify how the structural changes in the gut microbiota may extend lifespan, and to validate whether they could serve as biomarkers for the development of dietary anti-ageing interventions.
“We are now going into detailed molecular studies to understand mechanistically how calorie reduction changes the gut microbiota,” Prof. Zhao said.
The article can be found at: Zhang et al. (2013) Structural modulation of gut microbiota in life-long calorie restricted mice.
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Source: Nature Communications. Photo: AJC1/Flickr/CC.
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