Increased heart disease risk from red meat may stem from gut microbe response to digestion

Increased heart disease risk from red meat may stem from gut microbe response to digestion

Embargoed Until 4 am CT/5 am ET on Monday, August 1, 2022

Research Highlights:

  • A new study found that chemicals produced in the digestive tract by gut microbes after eating red meat (such as beef, pork, bison, venison) explained a significant portion of the increased risk of cardiovascular disease associated with higher consumption of Red meat.

  • High blood sugar and inflammation may also contribute to the increased cardiovascular risk associated with red meat consumption; however, blood pressure and cholesterol were not associated with increased CVD risk associated with red meat consumption.

  • Overall consumption of fish, poultry, and eggs was not associated with increased cardiovascular risk.

(NewMediaWire) – August 1, 2022 – DALLAS Chemicals produced in the digestive tract by gut microbes after eating red meat may help explain some of the increased risk of cardiovascular disease associated with red meat consumption, according to a new research published today in the American Heart Association’s peer-reviewed journal Arteriosclerosis, Thrombosis and Vascular Biology (ATVB).

In the United States and around the world, cardiovascular disease is the leading cause of death. Although the risk of developing cardiovascular diseases, including heart attacks and strokes, increases with age, other risk factors are influenced by lifestyle. Lifestyle and behaviors known to improve cardiovascular health include eating healthy foods, especially fruits and vegetables; regular physical activity; get enough sleep; maintain a healthy body weight; give up smoking; and control high blood pressure, high cholesterol, and high blood sugar.

“Most of the focus on red meat intake and health has been on blood cholesterol levels and dietary saturated fat,” said study co-senior author Meng Wang, Ph.D., a postdoctoral fellow in the Friedman School of Nutritional Sciences and Policy at Tufts University in Boston. “Based on our findings, novel interventions may be useful in addressing interactions between red meat and the gut microbiome to help us find ways to reduce cardiovascular risk.”

Previous research has found that certain metabolite chemical byproducts of food digestion are associated with an increased risk of cardiovascular disease. One of these metabolites is TMAO, or trimethylamine N-oxide, which is produced by gut bacteria to digest red meat that contains high amounts of the chemical L-carnitine.

High blood levels of TMAO in humans may be associated with an increased risk of CVD, chronic kidney disease, and type 2 diabetes. However, it is still unknown whether TMAO and related metabolites derived from L-carnitine can help explain the effects of red meat intake on cardiovascular risk and to what extent they may contribute to the cardiovascular risk associated with meat consumption.

To understand these questions, the researchers who conducted this study measured the levels of the metabolites in blood samples. They also examined whether blood sugar, inflammation, blood pressure, and blood cholesterol can explain the elevated cardiovascular risk associated with red meat consumption.

Study participants included nearly 4,000 of the 5,888 adults initially recruited between 1989 and 1990 for the Cardiovascular Health Study (CHS). Participants selected for the current study did not have clinical cardiovascular disease at the time of enrollment in CHS, an observational study of cardiovascular disease risk factors in adults aged 65 years and older. CHS follows 5,888 participants recruited from four communities: Sacramento, California; Hagerstown, Maryland; Winston-Salem, North Carolina; and Pittsburgh, Pennsylvania. The average age of participants at enrollment was 73 years, nearly two-thirds of participants were female, and 88% of participants self-identified as white. The median follow-up time of the participants was 12.5 years and up to 26 years in some cases. At the follow-up appointment, the participants’ medical history, lifestyle, health conditions, and sociodemographic characteristics, such as household income, education, and age, were assessed.

Several blood biomarkers were measured at the start of the study and again in 1996-1997. Fasting blood samples stored frozen at -80 C were analyzed for levels of various gut microbiomes associated with red meat consumption, including TMAO, gamma-butyrobetaine, and crotonobetaine.

In addition, all study participants answered two validated food frequency questionnaires about their usual dietary habits, including intake of red meat, processed meat, fish, poultry, and eggs, at the start of the study and again between 1995 and 1996. In the first questionnaire, participants indicated how often, on average in the previous 12 months, they had eaten given amounts of various foods, ranging from “never” to “almost every day or at least five times a week,” based on size of medium portions, which varied by food source. The second questionnaire used a frequency of ten average intake categories over the past 12 months, ranging from “never or less than once a month” to “six or more servings per day,” with standard serving sizes defined.

For the current analyses, the researchers compared the risk of cardiovascular disease among participants who ate different amounts of animal-based foods (ie, red meat, processed meat, fish, chicken, and eggs). They found that eating more meat, especially red meat and processed meat, was linked to an increased risk of atherosclerotic cardiovascular disease, a 22 percent increased risk for every 1.1 servings per day.

According to the authors, the increase in TMAO and related metabolites found in the blood explains about a tenth of this elevated risk. They also noted that blood sugar and general pathways of inflammation may help explain the links between red meat consumption and cardiovascular disease. Blood sugar and inflammation also appear to be more important in linking red meat consumption and cardiovascular disease than pathways related to blood cholesterol or blood pressure. Fish, poultry, and egg intake were not significantly associated with an increased risk of cardiovascular disease.

“Research efforts are needed to better understand the potential health effects of L-carnitine and other substances in red meat, such as heme iron, that have been associated with type 2 diabetes, rather than focusing only on the saturated fat,” Wang said.

The study had several limitations that may have affected its results. The study was observational, meaning it couldn’t control for all risk factors for cardiovascular disease, and it may not prove cause and effect between meat consumption and cardiovascular disease or its mediation by chemicals generated by meat. gut microbes. Also, food consumption was self-reported, so reporting errors were possible. And, since the majority of study participants were older white men and women in the United States, the findings may not apply to younger or more racially diverse populations.

Co-senior author is Zeneng Wang, Ph.D. Coauthors are Yujin Lee, Ph.D.; Heidi TM Lai, Ph.D.; Marcia C. de Oliveira Otto, Ph.D.; Rozenn N. Lemaitre, Ph.D., MPH; Amanda Fretts, Ph.D., MPH; Nona Sotoodehnia, MD, MPH; Matthew Budoff, MD; Joseph A. DiDonato, Ph.D.; Barbara McKnight, Ph.D.; W.H. Wilson Tang, MD; Bruce M. Psaty, MD, Ph.D.; David S. Siscovick, MD, MPH; Stanley L. Hazen, MD, Ph.D.; and Dariush Mozaffarian, MD, Dr.Ph. Authors’ declarations are listed in the manuscript.

The study was funded by the National Heart, Lung, and Blood Institute, with additional support from the National Institutes of Health, the National Institute of Neurological Disorders and Stroke, and the National Institute on Aging.

Studies published in American Heart Association scientific journals are peer-reviewed. Statements and conclusions in each manuscript are solely those of the study authors and do not necessarily reflect the policy or position of the Association. The Association does not represent or guarantee its accuracy or reliability. The Association receives funding mainly from individuals; Foundations and corporations (including pharmaceutical companies, device manufacturers, and other companies) also make donations and fund specific Association programs and events. The Association has strict policies to prevent these relationships from influencing scientific content. Revenues from pharmaceutical and biotechnology companies, device manufacturers and health insurance providers and general financial information for the Association are available here.

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