Keto Diet Doubles the Risk of Heart Attack, Stroke: Study

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March 6, 2023 – Keto diets can more than double the risk of serious heart problems, a new study shows.

People who ate foods high in fat and low in carbohydrates were more likely to have higher cholesterol and experience heart attacks or strokes, compared to people who followed a standard diet. Keto diets were also associated with a doubled risk of needing procedures to open up clogged arteries.

“Our study found that regular consumption of a self-reported diet low in carbohydrates and high in fat was associated with increased levels of LDL cholesterol — or ‘bad’ cholesterol — and a higher risk of heart disease,” researcher Iulia Iatan, MD, PhD, says in a statement. “To our knowledge, our study is one of the first to examine the association between this type of dietary pattern and cardiovascular outcomes.”

Presented this week at the American College of Cardiology’s annual meeting, the study evaluated health data for 305 people from the United Kingdom who were identified because they reported eating a keto-like diet during a 24-hour period at the beginning of the study. That group was compared with 1,220 people who were similar in age but who ate a standard diet. The study defined keto-like diets as having no more than 25% of daily calories from carbohydrates and getting more than 45% of calories from fat.

Most people in the study were women (73%), tended to be overweight, and the average age was 54. Researchers then analyzed health outcomes of the people for a nearly 12-year period. 

Keto dieters at the highest risk of heart and cardiovascular problems were those with the highest levels of LDL cholesterol. During the follow-up period, 9.8% of keto dieters experienced a new heart event, compared to 4.3% of people on a standard diet. The researchers suggested that people considering going on a keto diet consult a health care provider before starting the eating plan.

“While on the diet, it is recommended they have their cholesterol levels monitored and should try to address other risk factors for heart disease or stroke, such as diabetes, high blood pressure, physical inactivity and smoking,” said latan, who is an attending physician at St. Paul’s Hospital and University of British Columbia’s Centre for Heart Lung Innovation in Vancouver, Canada.

Keto diet is short for ketogenic diet. The terms refer to eating foods high in fat, which in turn helps the body produce ketones. Ketones are “a type of fuel that the liver produces from stored fat,” according to Harvard Health. The idea is to achieve a state of “ketosis,” where the body burns fat for energy instead of sugar from carbohydrates derived from grains, fruits, and vegetables. It can take several days to reach ketosis, and eating too much protein can also throw the whole cycle off.

Most people studied who were on the keto-like diet had increased health risks, but some had cholesterol levels that held steady or declined. Researchers said the reasons for that were unclear.

“One of our next steps will be to try to identify specific characteristics or genetic markers that can predict how someone will respond to this type of diet,” latan says.