Low-Carb Diets Increase Risk Of Heart Rhythm Disorder, Study Says

Popular diet trends such as keto and paleo advocate for severely restricting or limiting carbohydrates. But you might want to think twice before taking up that low-carb diet. A new study being presented at the American College of Cardiology's 68th Annual Scientific Session suggests that low-carb diets such as these could raise your risk of a common heart rhythm disorder called atrial fibrillation (AFib) — a condition that could be really dangerous.

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AFib is a shaky or irregular heartbeat that causes dizziness and fatigue. Long-term, AFib can lead to blood clots, stroke, heart failure, and other complications, according to the American Heart Association.

To analyze the risk of eating low-carb, researchers looked at data corresponding to approximately 14,000 people from a study overseen by the National Institutes of Health from 1985 to 2016. A low-carb diet was defined as a diet in which less than 44.8 percent of daily calories come from carbs. For perspective, the keto diet entails restricting carbohydrates to less than 10 percent of total calories. A high-carb diet entailed eating more than 52.4 percent of calories from carbs.

After an average of 22 years of follow-up, they found that people who followed a low-carb diet were the most likely of any group to receive an AFib diagnosis. Low-carb dieters were 18 percent more likely than those who followed a moderate carbohydrate diet and 16 percent more likely than those who followed a high-carb diet to get AFib. According to a release from the American College of Cardiology, these results suggest that these diets should be treated with more caution than people tend to think.

The researchers posited a few potential causes for the increased risk. You might think that these results were due to the large amounts of saturated fat consumed on low-carb diets such as keto — but the risk of AFib increased no matter what protein or fat was used to replace the calories from carbohydrates in participants' diets.

Rather, researchers said, the correlation could be due to the fact that people eating a low-carbohydrate diet tend to eat fewer vegetables, fruits, and grains. These foods are known to reduce inflammation that could cause heart problems. Additionally, replacing carbohydrate-rich foods with more protein and fat could lead to oxidative stress, which has also been associated with AFib.

Of course, correlation does not prove causation — other intervening factors could be affecting heart risk. And the research did not account for any changes in diet that occurred after the original study had completed.

However, cardiologist Dr. Nicole Harkin of Manhattan Cardiovascular Associates notes that this study isn't the only piece of evidence suggesting going keto might not be a good idea. "While low-carbohydrate (or ketogenic) diets can lead to short-term weight loss, we lack long-term studies to show that they are safe for long-term health," Dr. Harkin told The Daily Meal in an email. The diet, which is rumored to give people breath that smells like nail polish, might not be so safe after all. "Actually, the studies that we do have seem to support the idea that they actually may be harmful and increase the risk of cardiovascular disease."

"While avoiding refined grains and processed carbohydrates is undoubtedly good for cardiovascular health, cutting out a lot of fruits, vegetables, and whole grains (like oatmeal or farro) is a mistake, and we miss out on so much good fiber and nutrients," Harkin says. And heart health is just one of many ways quitting carbs entirely will affect your body.