Excessive meat consumption has been associated with a greater chance of having health problems, such as heart disease or diabetes, and even with an increased risk of cancer, but it is important to determine the effect that red meat or processed meats have on the health of older adults, since this population group is not only the most vulnerable to heart disease, but also the one that can benefit most from protein intake to compensate for the loss of muscle mass and strength associated with aging .
Scientists have been studying the relationship between cardiovascular diseases and the consumption of saturated fats, dietary cholesterol, sodium, nitrites, etc. for years, and the latest evidence suggests that among those responsible for the damage caused by these substances could be the specialized metabolites that our gut bacteria generate when we eat meat.
Now, new research analyzing data from 3,931 people over the age of 65 living in the United States has quantified the risk of developing atherosclerotic cardiovascular disease related to meat consumption and identified underlying biological pathways that may help explain this risk.
“Interactions between red meat, our gut microbiome, and the bioactive metabolites they generate appear to be an important pathway for heart disease risk.”
The study was led by researchers from the Tufts University Friedman School of Nutrition Science and Policy and the Lerner Research Institute at the Cleveland Clinic and found that higher meat consumption is associated with increased risk of atherosclerotic cardiovascular disease. ; specifically, a 22% increased risk for every 1.1 servings per day, and that approximately 10% of this increased risk is explained by an increase in the levels of three metabolites produced by bacteria in the intestine from nutrients that abound in the meat.
The researchers found higher risks and interrelationships with gut bacterial metabolites for red meat, but not for poultry, eggs, or fish. The work has been published in the journal Arteriosclerosis, Thrombosis, and Vascular Biology and is the first to study the interrelationships between foods of animal origin and the risk of atherosclerotic cardiovascular events, and the mediation of this risk by compounds produced by the microbiota intestinal, and by traditional risk factors for this disease, such as cholesterol and blood sugar and high blood pressure.
Eating poultry, eggs or fish did not increase cardiovascular risk
The research was based on years of data from the National Institutes of Health (NIH) Cardiovascular Health Study (CHS), a long-term observational study of cardiovascular disease risk factors in Americans aged 65 and older. . The 3,931 study participants were followed for a median of 12.5 years, and their average age at the start of the study was 73 years. The study adjusted for known risk factors such as age, gender, race/ethnicity, educational level, smoking, physical activity, eating habits, and many additional risk factors.
Several blood biomarkers were measured at the start of the study and this measurement was repeated during follow-up, including levels of trimethylamine N-oxide (TMAO) generated by the gut microbiome and two of its key intermediates, gamma-butyrobetaine and crotonobetaine, derived from L-carnitine, abundant in red meat.
The main conclusions of the investigation were:
“These findings help answer longstanding questions about the mechanisms that link meats to cardiovascular disease risk,” said Meng Wang, a co-author of the study and a postdoctoral fellow at the Friedman School. “Interactions between red meat, our gut microbiome, and the bioactive metabolites they generate appear to be an important pathway for risk, creating a new target for potential interventions to reduce heart disease.”
“Interestingly, we identified three main pathways that help explain the links between red and processed meat and cardiovascular disease: microbiome-related metabolites like TMAO, blood glucose levels, and general inflammation, and each of these seemed more important than pathways related to blood cholesterol or blood pressure,” said co-senior author Dariush Mozaffarian, dean of policy at the Friedman School, adding, “This suggests that when choosing foods of animal origin, it is less important to focus on on differences in total fat, saturated fat, or cholesterol, and more importantly, better understand the health effects of other components of these foods, such as L-carnitine and heme iron.”
Drawing on a wealth of clinical and dietary data from a large community of older adults, the research “links the gut microbial pathway of TMAO to animal-derived foods and increased risks of atherosclerotic cardiovascular disease,” concludes Stanley L. Hazen, section chief of preventive cardiology and rehabilitation at the Cleveland Clinic and co-senior author. “The study also advocates dietary efforts as a means of reducing that risk, as dietary interventions can significantly reduce TMAO.”
The researchers have warned that more studies are needed to see if their findings can be generalized to other ages and nationalities. In addition, they point out that it was the participants themselves who reported their dietary habits, and that since it is an observational study, cause and effect cannot be proven.
For now, people are advised to follow current lifestyle recommendations that help protect heart health, including a balanced diet rich in vegetables, fruits, whole grains, and other heart-healthy foods, as well as maintain a healthy weight, manage stress, avoid high blood pressure, exercise, get enough sleep, and stop smoking.
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