According to a new research from the University of Colorado Boulder, a compound produced in the gut when we eat red meat damages our arteries and may play a key role in increasing the risk of heart disease as we age.
The study
The study, published this month in the American Heart Association’s journal Hypertension, also suggests that people can prevent or even reverse such age-related decline through diet changes and targeted therapies, such as new nutritional supplements.
“Our work shows for the first time that this compound not only directly impairs artery function, but may also help explain the damage to the cardiovascular system that occurs naturally with age,” first author Vienna Brunt said, who is a postdoctoral researcher at the Department of Integrative Physiology.
Eat a piece of meat or a plate of scrambled eggs, and the resident gut bacteria will immediately start working to break it down. As they metabolize amino acids L-carnitine and choline, they produce a metabolic by-product called trimethylamine, which the liver converts to trimethylamine-N-oxide (TMAO) and sends through the bloodstream.
Previous studies have shown that people with higher levels of TMAO in their blood are more than twice as likely to have a heart attack or stroke and tend to die sooner.
But to date, scientists have not fully understood why.
Based on animal and human experiments, Brunt and her team set out to answer three questions: Does TMAO somehow harm our vascular system? If so, how? And could it be one reason why cardiovascular health worsens, even among people who exercise and don’t smoke, as we age?
The researchers measured the blood and artery health of 101 older adults and 22 young adults and found that TMAO levels increase significantly with age. (This coincides with a previous study on mice, which shows that the gut microbiome, or its collection of gut bacteria, changes with age, producing more bacteria that help create TMAO.)
Adults with higher blood TMAO levels had a significantly worse artery function, the new study found, and showed increased signs of oxidative stress or tissue damage on the lining of their blood vessels.
When the researchers fed TMAO directly to young mice, their blood vessels rapidly aged. “Just putting it in their diet made them look like old mice,” Brunt said. She noted that 12-month-old mice (the human equivalent of about 35 years of age) looked more like 27-month-old mice (humans of 80 years of age) after eating TMAO for several months.
A link to cognitive decline?
The preliminary data also reveal that mice with higher levels of TMAO show learning and memory decline, suggesting that the compound may also play a role in age-related cognitive decline.
On the other hand, the old mice that ate a compound called dimethylbutanol (found in small amounts in olive oil, vinegar, and red wine) saw a reversal in their vascular dysfunction. Scientists believe that this compound prevents the production of TMAO.
Brunt noted that everyone, even a young vegan, produces some TMAO. But over time, eating a lot of animal products can take its toll. “The more red meat you eat, the more you feed the bacteria that produce it,” she said. Lead author Doug Seals, director of the Integrative Physiology Laboratory of Aging, said the study is an important breakthrough because it sheds light on why our arteries erode with age, even those of healthy people.
The future
“Aging is the largest risk factor for cardiovascular disease, primarily as a result of oxidative stress on our arteries,” Seals said. “But what causes oxidative stress in our arteries as we age? That has been the great unknown. This study identifies a potential very important factor.” The research team is now exploring compounds that could block TMAO production in order to prevent age-related vascular deterioration. For the time being, consider skipping steak and roasting some tofu, since a plant-based diet can also lower TMAO levels.
Link: https://www.sochob.cl/web1/que-hace-que-las-arterias-envejezcan-estudio-explora-nuevo-vinculo-con-bacterias-intestinales-y-dieta/
Date: July 17th, 2020
Link: : https://medicalxpress.com
Reference: Viena E. Brunt VE, Gioscia-Ryan RA, Casso AG, et al. Trimethylamine-N-Oxide promotes age-related vascular oxidative stress and endothelial dysfunction in mice and healthy humans. Hypertension, 2020; 76(1):101.
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