One key finding of interest to clinical laboratory scientists is that this research study indicates that the human microbiome may more closely correlate with blood markers of metabolic disease than the genome of individuals
In the search for more sensitive diagnostic biomarkers (meaning the ability to detect disease with smaller samples and smaller quantities of the target biomarker), an international team of researchers has teased out a finding that a panel of multiple biomarkers in the human microbiome is more closely correlated with metabolic disease than genetic markers.
The team also discovered that the foods an individual ate had a more powerful impact on their microbiomes than their genes. The study participants included several sets of identical twins. The researchers found that identical twins shared only about 34% of the same gut microbes. People who were unrelated shared 30% of the same gut microbes.
This is a fascinating insight for pathologists and microbiologists involved in the study of the human microbiome for use in development of precision medicine clinical laboratory testing and drug therapies.
Microbiome Markers for Obesity, Heart Disease, and More
The study began in 2018, when an international team of researchers analyzed the gut microbiomes, diets, and blood biomarkers for cardiometabolic health obtained from 1,100 mostly healthy adults in the United Kingdom (UK) and the United States (US). They collected blood samples from the participants before and after meals to examine blood sugar levels, hormones, cholesterol, and inflammation levels. Sleep and activity levels also were monitored. Participants had to wear a continuous glucose monitor for two weeks during the research period.
The scientists discovered that the composition of a healthy gut microbiome is strongly linked to certain foods, food groups, nutrients, and diet composition. They identified markers for obesity, impaired glucose tolerance, and cardiovascular disease in the gut bacteria.
“When you eat, you’re not just nourishing your body, you’re feeding the trillions of microbes that live inside your gut,” genetic epidemiologist Tim Spector, MD, FmedSCi, told Labroots. Spector is a professor of genetic epidemiology at King’s College London and one of the authors of the study.
The scientists found that a diet rich in nutrient-dense, whole foods was more beneficial to a healthy gut microbiome, which can be an indicator of good health. Individuals who ate minimally processed foods, such as vegetables, nuts, eggs, and seafood were more likely to have healthy gut bacteria than individuals who consumed large amounts of highly processed foods, like juices and other sweetened beverages, processed meats, and refined grains and foods that were high in added sugars and salt.
“It goes back to the age-old message of eating as many whole and unprocessed foods as possible,” Sarah Berry, PhD, a nutrition scientist at King’s College London and a co-author of the study told The New York Times. “What this research shows for the first time is the link between the quality of the food we’re eating, the quality of our microbiomes, and ultimately our health outcomes,” she added.
The researchers concluded that heavily processed foods tend to contain very minimal amounts of fiber, a macronutrient that helps promote good bacteria in the gut microbiome and leads to better metabolic and cardiovascular health.
They found that people who had healthy blood sugar levels following a meal had higher levels of good bacteria called Prevotella copri, a genus of gram-negative bacteria, and Blastocystis, a genus of single-celled heterokont parasites, present in their guts. These bacteria are associated with lower levels of visceral fat, which accumulates around internal organs and increases risk of heart disease.
These “good” microbes also are affiliated with lower levels of inflammation, better blood sugar control, and lower spikes in blood fat and cholesterol levels after meals.
The study also found that different people have wildly varying metabolic responses to the same foods, partially due to the types of bacteria residing in their gut microbiome. The consumption of some foods is better for overall health than other foods, but there is no definitive, one-size-fits-all diet that works for everyone.
“What we found in our study was that the same diet in two different individuals does not lead to the same microbiome, and it does not lead to the same metabolic response. There is a lot of variation,” Andrew Chan, MD, Professor of Medicine at Harvard Medical School, told The New York Times. Chan is also Chief of the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital and co-author of the study.
Small Changes in Diet, Big Impact to Health
The team is now planning a clinical trial to test whether changes in diet can alter levels of good and bad microbes in the gut. If proven to be true, such information could help clinicians design personalized nutritional plans that would enable individuals to improve their gut microbiome and their overall health.
“As a nutritional scientist, finding novel microbes that are linked to specific foods, as well as metabolic health, is exciting,” Berry told News Medical. “Given the highly personalized composition of each individual’s microbiome, our research suggests that we may be able to modify our gut microbiome to optimize our health by choosing the best foods for our unique biology.
“We think there are lots of small changes that people can make that can have a big impact on their health that might be mediated through the microbiome,” Berry told The New York Times.
The researchers published their findings in Nature Medicine, titled, “Microbiome Connections with Host Metabolism and Habitual Diet from 1,098 Deeply Phenotyped Individuals.”
More research and clinical trials are needed before diagnostic tests that use microbiome biomarkers to detect metabolic diseases can be developed. But these early research findings are a sign to pathologists and clinical laboratory managers that microbiome-based assays may come to play a more significant role in the early detection of several metabolic diseases.