The Effect of a “Keto-Like” Diet on Heart Disease

A large portion of the population of the developed world is now overweight or obese.  A survey from January 2020 showed that 69% of Canadians surveyed had tried the keto diet for weight loss.  Another 48% were considering adopting a keto diet to improve their health. (1)  Keto diets, consisting of low amounts of carbohydrates and high amounts of fat, have become popular in recent decades as a quick way to lose weight and control blood sugar through the boosting of fats instead of carbohydrates as the body’s primary energy source.  Carbohydrates are the human body’s optimal fuel source for the provision of the energy needed for daily life.   However, as a way to prevent starvation when carbohydrates are limited, the human body is able to use fat as a back-up fuel source with the liver capable of breaking down fat and, from it, produce ketones which can then serve as a temporary alternative source of energy. (2)

A recent observational study was presented at the American College of Cardiology Annual Scientific Session in March 2023.  It examined the relationship between a low-carb high-fat diet (“keto-like” diet) and the risk of undesirable cardiovascular events.  Lead author was Dr. Iulia Iatan, MD, physician scientist at the University of British Columbia’s Healthy Heart Program and Centre for Heart Lung Innovation in St. Paul’s Hospital, Vancouver, Canada. (3)

For this study, data from the UK Biobank was utilized.  This is a large-scale prospective population-based dataset that contains the health information of more than 500,000 individuals in the UK who were followed for at least ten years. When enrolled in this databank, 70,684 participants completed a one-time self-reported 24-hour diet questionnaire (that has been extensively validated) and had blood samples drawn to check their lipid levels.  From this group, 305 individuals were identified whose reported diet was “keto-like”, described for the purposes of this research as obtaining less than 25% of their daily calories from carbohydrates and more than 45% of their daily calories from fats.  (Strict keto diets generally consist of less than 10% carbohydrates and 60% to 70% fats with proteins at 20% to 30%.) These participants were matched in age and sex with the data of 1,220 other individuals from the UK Biobank who reported consuming a standard diet.  (The standard diet was defined as one not meeting the criteria of a “keto-like” diet and having more balanced eating habits.)  For this investigation, the makeup of both groups was approximately 73% women with an average age of 54 years.  Those on a “keto-like” diet had an average body mass index (BMI) of 27.7; those on a standard diet had an average BMI of 26.7.  A BMI of 25 to 30 is in the overweight range. (3)

The primary goal of this research was to observe the impact of a low-carb high-fat diet (“keto-like” diet) on blood lipid (fat) levels with the secondary goal being the association between low-carb high-fat diets and major harmful cardiovascular events including artery blockages requiring stents, chest pain, heart attack, stroke and peripheral atrial disease. (3)

Results of this study showed the following (3);

• Those eating a “keto-like” diet had higher levels of total cholesterol, LDL-cholesterol (“bad” cholesterol) and apolipoprotein-ß (apoß). Both LDL-cholesterol and apoß are known risk factors for heart disease but previous studies have shown that elevated apoß may be a better predictor of cardiovascular disease risk than LDL-cholesterol. (4)

Note: Apolipoprotein-ß is a protein component present on LDL and other lipoprotein particles that are known risk factors for heart disease.

• After an average of 11.8 years of follow-up, 9.8% of the people eating the “keto-like” diet experienced a new cardiac adverse event while 4.3% of those on a standard diet experienced a new cardiac adverse event. These results occurred after adjustments for other risk factors.
• To summarize, cardiovascular risk was more than doubled in those eating a “keto-like” diet compared to those eating a more standard diet.

 

This investigation was observational and based on self-reported information so it can only show an association, not a causal relationship, between a “keto-like” diet and the increased risk for major cardiovascular events.  Nevertheless, people considering a low-carb high-fat diet for any reason need to be aware that doing so could lead to a significant rise in their blood lipid levels and an increase in their potential cardiovascular risks. If they do choose to embark on a keto or “keto-like” diet, their healthcare professional should monitor their cholesterol and apoß levels.  Ideally, other risk factors for heart disease such as diabetes, high blood pressure, physical inactivity and smoking should also be addressed and minimized as much as possible.

With the wide and growing acceptance of “keto-like” diets in a population of increasingly overweight people, it is essential that the harmful effects of these types of diets are illuminated.  There is great need for further research in the form of prospectively designed studies to confirm the findings of this analysis and to educate people about better, healthier ways to lose weight.

For more information on low-carb high-fat diets see my blogs from December 2018 entitled “The Newest Evidence on Eating Low-Carb and Longevity” and, from October 2021, “Consider This Before Deciding to Eat Keto”.

 

SOURCES:

1  https://www.statista.com/statistics/1102757/keto-diet-leading-motives-for-canadians-trying-it/

2  https://www.health.harvard.edu/staying-healthy/should-you-try-the-keto-diet

3   Iulia Iatan.  Association of a Low-carbohydrate High-fat (Ketogenic) Diet With Plasma Lipid Levels and Cardiovascular Risk in a Population-based Cohort.  Presented during the American College of Cardiology Annual Scientific Session (ACC23/WCC), March 4 to 6, 2023 in New Orleans.

4  Behbodikhah, J., Ahmed, S., Elyasi, A., Kasselman, L.J., De Leon, J., Glass, A.D., Reiss, A.B. Apolipoprotein B and Cardiovascular Disease: Biomarker and Potential Therapeutic Target. Metabolites. 2021 Oct 8; 11(10): 690. Doi: 10.3390/metabo11100690. PMID: 34677405; PMCID: PMC8540246.