Few people know how closely heart health and kidney health are linked. Indeed, coronary artery disease is the Number One cause of death in people with chronic kidney disease (CKD). Even after starting dialysis or receiving a kidney transplant, their risk of heart attack remains sky-high.
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Gut bacteria may be a link
Researchers at Cleveland Clinic think they may have discovered an important reason why. It’s a substance called TMAO, which bacteria in the gut create from a substance found in meat and eggs.
A team of researchers led by Stanley Hazen, MD, PhD, Chair of Cellular and Molecular Medicine and Section Head of Preventive Cardiology and Rehabilitation at Cleveland Clinic, discovered a connection between high TMAO levels and increased risk of heart attack, stroke and death.
More recently, Dr. Hazen and W.H. Wilson Tang, MD, staff cardiologist and Director of the Center for Clinical Genomics, linked TMAO with CKD. Their study found that people with CKD don’t excrete TMAO normally, so they have high TMAO levels. Those with the high blood TMAO levels had twice the risk of death over the ensuing 5 year period relative to the people with the low levels. Further, they showed through laboratory studies that TMAO itself directly contributed to the development of CKD.
TMAO responds to changes in diet
The association intrigues Joseph Nally, MD, Director of the Center for Chronic Kidney Disease at Cleveland Clinic.
“This is an attractive hypothesis based on plausible biology,” he says. “The exciting thing is that TMAO is responsive to changes in diet. Eat red meat and TMAO goes up; become a vegetarian, and TMAO goes down.”
This will allow us to test the association and determine whether TMAO is actually responsible for death and destruction, or is merely a bystander.
“A lot of things are associated with increased death rates in CKD, says Dr. Nally, “including metabolic acidosis and metabolic syndrome. The key is to prove cause and effect.”
“Dr. Hazen and his team hope to modify TMAO with diet or a yet-to-be-developed drug and see if it changes outcomes. It’s an important line of investigation, and something Cleveland Clinic’s heart and kidney teams would like to pursue,” says Dr. Nally.