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Mar 12, 2019

Low-Carb Diet Tied to Common Heart Rhythm Disorder

Study suggests using caution when restricting carbohydrates for weight loss due to atrial fibrillation concern.

Cutting back on carbs could spell trouble for your heart, based on a recent study that linked low carbohydrate consumption to increased risk for atrial fibrillation, the most common type of heart rhythm disorder. Findings will be presented March 16 at the American College of Cardiology’s 68th Annual Scientific Session and suggest using caution when restricting carbohydrates for weight loss.

The study, which analyzed the health records for nearly 14,000 people over more than two decades, is the first to look at the relationship between carbohydrate intake and risk for atrial fibrillation.

Atrial fibrillation, often referred to as AFib, is the most common type of heart rhythm disorder. It affects as many as 6.1 million U.S. adults and drastically increases risk for stroke. We know that a healthy lifestyle helps reduce risk for AFib and other heart problems. However, little is known about the long-term impact of low-carb diets on heart health.

Using data from ARIC (Atherosclerosis Risk in Communities), this study looked at carbohydrate consumption among nearly 14,000 U.S. adults between 1985 and 2016. Based on responses from dietary surveys, researchers grouped participants into low-carb (less than 44.8% of daily calories), moderate carb (44.8-52.4% of daily calories) and high-carb diets (more than 52.4% of daily calories).

All participants were free of AFib at the start of the study, but nearly 1,900 were diagnosed with AFib during an average of 22 years of follow-up.

After analysis, researchers found that participants with low carbohydrate intake were 18% more likely to develop AFib than those with moderate carbohydrate intake and had 16% greater risk for AFib than those with a high-carb intake.

Authors note that while the study shows an association, it does not prove that a low-carb diet directly increases risk for AFib. However, experts still have a few explanations for the possible association.

First, people eating a low-carb diet tend to eat fewer vegetables, fruits and grains, which are known to reduce inflammation. Increasing protein intake while cutting back on carbs can also lead to oxidative stress, which occurs when the body has trouble defending against free radicals that can cause damage to cells, protein and DNA. Both of these conditions can increase risk for atrial fibrillation, as can a general increased risk of other heart problems.

“The long-term effect of carbohydrate restriction is still controversial, especially with regard to its influence on cardiovascular disease,” said Xiaodong Zhuang, MD, PhD, a cardiologist at the hospital affiliated with Sun Yat-Sen University in Guangzhou, China, and the study’s lead author. “Considering the potential influence on arrhythmia, our study suggests this popular weight control method should be recommended cautiously.”

There are many different low-carb diets that have become popular in the past few decades, such as the ketogenic, paleo and Atkins diets. While they may differ slightly, most are rich in proteins and limit intake of sugars, grains, legumes, fruits and starchy vegetables. In the recent study, it didn’t seem to matter which type of diet participants were on when it came to risk for AFib.

“Low carbohydrate diets were associated with increased risk of incident AFib regardless of the type of protein or fat used to replace the carbohydrate,” Zhuang said.

Questions for You to Consider

  • What is a heart-healthy diet?

  • A heart-healthy diet is full of fruits, vegetables, beans and whole grains and includes low-fat dairy, fish and nuts as part of a balanced diet. It’s important to limit intake of added sugars, salt (sodium) and bad fats (saturated and trans fats).

  • What is atrial fibrillation?

  • Atrial fibrillation is an irregular heart rhythm caused by abnormal, chaotic electrical impulses in the heart’s upper chambers, the atria. These electrical impulses, which interfere with the heart’s natural pacemaker, fire so rapidly the atria cannot beat with a regular rhythm or squeeze out blood effectively. Instead, they merely quiver while the ventricles, the heart’s lower chambers, beat rapidly.

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Infographic: AFib