If You Eat These 4 Popular Foods, Get a Blood Test, Doctor Warns
They may be delicious—but they contain a toxic compound that can hurt your heart.
Getting blood drawn doesn't exactly top anyone's list of most-fun activities. But a new blood test that measures levels of a toxic compound produced by popular foods we eat can help predict the future of your heart health—and ultimately help lower your risk of heart attack, stroke, and premature death.
Trimethylamine N-oxide (TMAO) is a toxic compound that's produced by the interaction between certain foods and gut microbes during digestion. "TMAO is not present in food," explains Purna Kashyap, MBBS, a gastroenterologist at the Mayo Clinic. However, when you eat certain foods, your gut microbes convert them into trimethylamine, which your liver then turns into TMAO, he explains. Over time, TMAO accumulates in your blood, increasing your risk of atherosclerosis (plaque build-up in your arteries) and making you more vulnerable to cardiovascular disease, heart attack, and stroke.
People with elevated TMAO levels have twice the risk of experiencing a heart attack, stroke, or other heart problems, according to the Harvard Medical School. To lower TMAO levels. Kashyap recommends following a fiber-rich diet and consuming plenty of olive oil, which contains "one of the inhibitors of the enzyme required to make TMAO." Avoiding certain food will help, too. Read on to find out which four foods put you at highest risk—and ask your doctor for a blood test if you eat them regularly.
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While there are varying views on how healthy—or unhealthy—red meat is for us, certain studies associate it with an increased risk of several chronic diseases. And although you may have heard that the saturated fat in red meat is what raises your heart disease risk, mounting evidence shows that the TMAO produced from digesting red meat increases your susceptibility to heart disease and premature death.
"Red meat is the most commonly implicated [food] to increase TMAO levels," says Kashyap. "An increase in TMAO levels is associated with increased risk of heart attack and stroke, and it is also associated with chronic kidney disease." So next time you decide to sizzle a steak for dinner, consider swapping the red meat for a heart-healthy plant protein, such as tofu or lentils. Plant-based proteins are nutrient-dense and can lower your risk of heart disease, according to the Physicians Committee for Responsible Medicine.
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Along with red meat, saltwater fish—such as salmon, tuna, and cod—can cause high concentrations of TMAO in your blood. Saltwater fish are rich sources of choline, lecithin, and carnitine, which spike TMAO in the blood. According to a Feb. 2022 study published in the European Journal of Nutrition, saltwater fish have high concentrations of TMAO in their muscles to help protect them from external environmental factors, such as water pressure and cold temperatures.
For the study, researchers had 50 participants consume various species of saltwater fish for five weeks while having weekly blood samples taken. The findings concluded that certain kinds of fish and seafood contain high levels of TMAO and "may induce a transient elevation in TMAO levels in some individuals." Translation? Fish can spike your TMAO levels, thereby compromising your heart health.
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Eggs are often touted for their health benefits, but eating too many could mean trouble for your heart. Eating two or more eggs per day significantly increases TMAO levels in your blood and urine, according to a 2014 study published in The American Journal of Clinical Nutrition. Egg yolks are high in choline at 115 milligrams per serving—approximately 25 percent of your daily requirement. If you eat two eggs at breakfast, that puts you over half the recommended daily amount of choline. If you want to protect your heart but can't imagine breakfast without eggs, there are many plant-based egg products available that replicate the egg experience without the health consequences.
With all the buzz around non-dairy milks these days—along with the fact that 68 percent of the global population is lactose intolerant—many people are questioning whether dairy is as good for them as they once thought it was. And what's more, a 2015 study published in the Journal of Nutrition found that high-dairy diets are associated with increased TMAO levels and inflammation. If you frequently enjoy animal-based milk, cheese, yogurt, and other dairy products, you may want to have your TMAO levels checked.
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