Gut bacteria make red meat bad for the heart

River D'Almeida, Ph.D
2 min readAug 8, 2022

Digesting animal proteins creates byproducts that spike the risk of cardiovascular disease

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Nutritionists advise that red meat should be eaten in moderation, because too much spike the risk of cardiovascular disease.

But, how?

Scientists aren’t entirely sure. One camp says it’s the saturated fat in animal proteins, while others say that everything from meat additives like salt and nitrates to those charred bits on barbequed meat are to blame.

The bottom line is that there isn’t enough evidence to support one theory over another.

Now, researchers from Tufts University have identified a new, somewhat unlikely mechanism: when we eat meat, bacteria in the gut churn out distinct metabolites. It’s these byproducts that raise blood pressure, decrease insulin sensitivity, and ‘bad’ cholesterol.

“These findings help answer long-standing questions on mechanisms linking meats to risk of cardiovascular diseases,” said Meng Wang, a postdoctoral fellow at the Friedman School of Nutrition Science and Policy at Tufts University.

“The interactions between red meat, our gut microbiome, and the bioactive metabolites they generate seem to be an important pathway for risk, which creates a new target for possible interventions to reduce heart disease.”

Wang and colleagues tracked close to 4,000 participants over a decade to look for pathways that connect nutrition with heart disease risk.

Dariush Mozaffarian, a senior author on the study said that the team found three major pathways that link metabolites produced by the gut microbiome to inflammation, blood glucose levels, and blood pressure.

“This suggests that, when choosing animal-source foods, it’s less important to focus on differences in total fat, saturated fat, or cholesterol, and more important to better understand the health effects of other components in these foods, like L-carnitine and heme iron,” said Mozaffarian.

Some of the key findings of the paper include:

  • Higher intake of unprocessed and processed red meat were associated with a higher incidence of cardiovascular disease
  • People with heart disease had higher levels of microbiome metabolites in their blood
  • Fish, poultry, and eggs were not linked with a heightened risk of cardiovascular disease



River D'Almeida, Ph.D

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