The report also suggests that an individual may be able to prevent or even reverse this age related decline by making some simple dietary changes and implementing targeted therapies such as nutritional supplements.
“Our work shows for the first time that not only is this compound directly impairing artery function, it may also help explain the damage to the cardiovascular system that naturally occurs with age,” said first author Vienna Brunt, a postdoctoral researcher in the Department of Integrative Physiology.
When a person eats a portion of steak or a plate of scrambled eggs the resident gut bacteria immediate set to work at breaking it down, as they metabolize the amino acids L-carnitine and choline they churn out trimethylamine metabolic byproducts which the liver then converts into trimethylamine-N-Oxide, known as TMAO, and sends it coursing through the bloodstream.
Studies have shown that those with higher blood levels of TMAO are more than twice as likely to experience a heart attack or stroke, and those with higher blood levels of TMAO also tend to die earlier. However, scientists don’t fully understand why.
This team set out to answer three questions drawing on both animal and human experiments: Does TMAO somehow damage the vascular system? If it does damage the vascular system how? And is it one of the reasons why cardiovascular health declines, even among those who don’t smoke and exercise as they get older?
Blood and arterial health of 101 older adults and 22 young adults were measured, which revealed that TMAO levels significantly increase with age. This finding supports a previous mouse study showing the gut microbiome changes with age, breeding more bacteria that help to produce TMAO. Adults with higher levels of TMAO were found to have significantly worse artery function and showed greater signs of oxidative stress or tissue damage in the lining of their blood vessels.
When TMAO was fed directly to young mice their blood vessels aged rapidly. “Just putting it in their diet made them look like old mice,” said Brunt. She noted that 12-month-old mice (the equivalent of humans about 35 years old) looked more like 27-month-old mice (age 80 in people) after eating TMAO for several months.
Preliminary data suggest that mice with higher levels of TMAO also exhibit decreases in learning and memory, indicating that it may play a role in age related cognitive decline.
Older mice that ate dimethyl butanol were observed to experience their vascular dysfunction reverse; the team believes that this compound may prevent the production of TMAO. Dimethyl butanol can be found in olive oil, vinegar, and red wine in trace amounts.
The team notes that even a young vegan will produce some TMAO, but over time consuming a lot of animal products may take a toll on vascular health. “The more red meat you eat, the more you are feeding those bacteria that produce it,” said Brunt.
According to senior author Doug Seals who is the director of the Integrative Physiology of Aging Laboratory this study is an important breakthrough as it sheds new light in why the arteries erode with age, even within the seemingly healthiest of people.
“Aging is the single greatest risk factor for cardiovascular disease, primarily as a result of oxidative stress to our arteries,” said Seals. “But what causes oxidative stress to develop in our arteries as we age? That has been the big unknown. This study identifies what could be a very important driver.”
The team is further exploring possible compounds that may block the production of TMAO to prevent age related vascular decline. Until something is found perhaps it may be a good idea to skip that big steak or at least limit the intake of animal products to incorporate more plant based options, as the gut friendly plant based diet can help to reduce levels of TMAO as well.
