Keto-style diet may be tied to heart disease

A low-carb, low-fat “ketotic” diet may be linked to higher levels of “bad” cholesterol and double the risk of cardiovascular events such as clogged arteries, heart attacks and strokes, according to new research.

“Our study showed that regular consumption of a diet high in carbohydrates and fat is associated with increased levels of LDL cholesterol, or ‘bad’ cholesterol, and an increased risk of heart disease,” said lead study author Dr. Iulia Iathan with the Healthy Heart Program Prevention Clinic, St. Paul’s Hospital and the Center for Heart Lung Innovation at the University of British Columbia in Vancouver said in a press release.

“This study makes an important contribution to the scientific literature and suggests that the harms outweigh the benefits,” said Christopher Gardner, a professor of medicine at the Stanford Prevention Research Center, who conducted clinical trials of the keto diet. Gardner was not involved in the study.

“Elevated LDL cholesterol should not be dismissed as just a minor side effect of a VLCD (very low-carbohydrate diet) or ketogenic diet,” Gardner said, pointing to the increased risk of cardiovascular events in people with higher blood ketone levels. , when compared to those on a more standard diet.

In the study, researchers defined a low-carbohydrate, high-fat (LCHF) diet as 45% of total daily calories coming from fat and 25% from carbohydrates. The study, which has not been peer-reviewed, was presented Sunday at the American College of Cardiology’s annual scientific session in conjunction with the World Congress of Cardiology.

“The rationale for our study was that we would see patients in our cardiovascular prevention clinic with severe hypercholesterolemia following this diet,” Ethan said during a presentation at the session.

Hypercholesterolemia, or high cholesterol, increases a person’s risk of heart attack or other adverse cardiovascular events.

“This got us thinking about what these low-carbohydrate, high-fat diets have to do with lipid levels and cardiovascular disease. And so despite that, there’s limited data on this relationship,” he said.

Researchers compared the diets of 305 people eating an LCHF diet with nearly 1,200 people eating a normal diet, using health data from the UK Biobank database, which has followed people for at least a decade.

The researchers found that people on the LCHF diet had higher levels of low-density lipoprotein, also known as LDL, cholesterol, and apolipoprotein B. Apolipoprotein B is a protein that coats LDL cholesterol proteins and may be a better predictor of heart disease than high LDL cholesterol levels. can.

The researchers also observed that the total fat intake of the LCHF diet participants was higher in saturated fat and consumed twice as much animal sources (33%) compared to the control group (16%).

“After a median follow-up of 11.8 years and after adjusting for other risk factors for heart disease, such as diabetes, high blood pressure, obesity and smoking; several major cardiovascular events, such as blockages in arteries that had to be opened with stenting procedures, heart attack, stroke, and peripheral artery disease,” the researchers found, according to a news release.

The researchers said in a statement that their study “can only show an association between diet and increased risk of major cardiac events, not causation,” because it was an observational study, but their findings merit further study, “esp. when approximately 1 in 5 Americans report following a low-carb, keto-like, or full keto diet.”

Ethan said limitations of the study included measurement errors that occur when dietary assessments are self-reported, the study’s small sample size, and that most of the participants were British and did not include other ethnic groups.

The study also looked at the long-term effects of following the diet, while most people who follow a keto-like diet tend to follow it intermittently for shorter periods of time.

The majority of participants, 73%, were women, which Ethan says is “pretty interesting to see, but it also supports the available literature that women in general tend to be more dieters, tend to be more interested in their diet with change”. lifestyle.”

When asked if there were groups that were not harmed by following the LCHF diet, Ethan said how long people stay on the diet and whether or not they lose weight “could counterbalance any increase in LDL.”

“It’s important to remember that every patient reacts differently. And so there really is inter-individual variability in response. What we found is that, you know, on average, patients tend to increase their LDL cholesterol levels,” he said. .

Dr. David Katz, a lifestyle medicine specialist who was not involved in the study, said, “There are many different ways of designing an LCHF diet, and it is very unlikely that they will all have the same effect on serum lipids or cardiac events.”

However, he added. “That the LCHF diet was associated with adverse outcomes in this study is a reality check for those who adopt such diets simply because they are trendy.”

Most health experts say the trendy keto diet, which bans carbs so your body burns fat for fuel, cuts out healthy foods like fruits, beans and grains, and whole grains. On the keto diet, you limit your carbohydrate intake to just 20 to 50 per day, the lower the better. To put that into perspective, a medium-sized banana or apple has about 27 carbs, a full day’s worth of servings.

“The food groups that must be eliminated to achieve ketosis are the main sources of dietary fiber, as well as many important nutrients, phytochemicals and antioxidants. This is a concern for many health professionals considering a VLCD or ketogenic diet. is harmful to long-term health,” Gardner said.

Keto is short for ketosis, a metabolic state that occurs when your liver starts using stored fat to produce ketones for energy. The liver is programmed to do this when your body loses access to its preferred fuel, carbohydrates, and thinks it’s starving.

The keto diet has been around since the 1920s, when a doctor discovered it as a way to control seizures in children with epilepsy that didn’t respond to other treatments.

Low-carb diets like keto rely heavily on fat for satiety. At least 70% of the keto diet will be made up of fat; some say it’s more like 90%.

While you can get all that fat from healthy unsaturated fats like avocado, tofu, nuts, seeds, and olive oil, the diet also allows for saturated fats like lard, butter, and coconut oil, as well as full-fat milk, cheese, and mayonnaise. Eating foods high in saturated fat increases the body’s production of LDL cholesterol, which can build up inside the arteries and restrict blood flow to the heart and brain.