Key News in Family Medicine May 03, 2019 (6 of 8)

A newly discovered relationship between genetic variation and the gut microbiome could help nutritionists customize their recommendations.

People with a large number of copies of a gene called AMY1, which expresses a salivary enzyme to break down starch, was strongly correlated with a certain profile of intestinal and oral bacteria, according to a new study from Cornell University.

A family of bacteria called Ruminococcaceae proliferates in the intestines when more of this salivary enzyme – called amylase – is available. Bacteria are known to break down resistant starch so that it can be digested, which human amylases can not do. The degradation of these difficult-to-digest starches offers nutritional benefits.

In the prehistoric era and afterwards, people with more copies of this gene could have benefited when calories were scarce, for example during cold seasons and famines.

"This will likely bring an extra supply of starch," said Angela Poole, badistant professor in the Division of Nutritional Sciences and senior author of a study published April 10 in the journal Cell Host & Microbe.

Ruth Ley, director at the Max Planck Institute for Developmental Biology in Germany and previously at Cornell's Department of Molecular Biology and Genetics, is the lead author of the study.

The findings suggest the need for personalized nutrition, said Poole, under which health professionals could make the patient's decisions. AMY1 the number of gene copies to consider in dietary counseling. Other researchers have linked the gene to the glucose response to meals, insulin resistance, and body mbad index.

In addition, a higher number of copies of the AMY1 The gene was also correlated with higher rates of Porphyromonas, bacteria in the mouth badociated with periodontitis, a gum disease, although additional studies are needed to distinguish cause or coincidence.

In this study, Poole and colleagues examined existing data on genetic and stool samples from a British population of nearly 1,000 people. They were looking for evidence of whether AMY1 the number of gene copies influences the microbiome; they examined the results of a subset of 100 people from the British population, 50 with a projected high copy number (5% higher) and 50 with a low copy number (5% lower). "High[[[[AMY1 gene]number of copies correlated with a certain pattern of intestinal bacteria, "said Poole.

Poole then determined the number of AMY1 copies in over 100 people from Ithaca, NY. She found a distribution between 2 and 30 copies. The team also collected stool data and identified bacteria badociated with high and low rates of AMY1 number of gene copies. Twenty-five of these study participants were then submitted to a standard diet for 2 weeks. "I wanted to make sure they were eating the same thing and that they were eating starch," Poole said. The team then collected saliva and stool samples and found that in the intestine the results matched those in the UK population study.

The study was funded by the David and Lucile Packard Foundation, the Arnold and Mabel Beckman Foundation, the National Science Foundation, the Hartwell Foundation and the Max Planck Society.