Is the Keto Diet Bad for Your Heart?

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Written by Myra Safdar, Medical Doctor and medically reviewed by Abby Courtenay

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The keto or ketogenic diet involves the dietary intake of low-carbohydrate, high-fat meals. As the body primarily relies on glucose as its source of energy, the intake on a high-fat keto plan forces the body into a state of ketosis.

During starvation or fasting, the body converts fats into ketone bodies, which are then used by the body as a metabolic fuel. This effect is similar to the one achieved by the intake of the keto diet. Therefore, this way of eating is a very powerful and effective way to lose weight. 

The ketogenic way of eating has been successfully used to treat epilepsy in children. In addition to improving weight loss and symptoms of type 2 diabetes mellitus, recent research also suggests that this eating style can improve symptoms of depression and fatigue in patients with multiple sclerosis. However, when it comes to cardiovascular health, the available evidence for the ketogenic plan is conflicting. 

So is keto bad for your heart? This article explores the potential benefits and side effects of keto for heart health1-4.

 

Is Keto Heart Healthy?

According to the dietary guidelines published by the American Heart Association in 2021, there is currently insufficient evidence to recommend keto for cardiovascular health. This is because not enough research has been done to study the effect of keto on the heart. 

However, there is emerging evidence to suggest that this eating style can potentially improve some of the risk factors that later lead to heart disease.

A review published by the American College of Cardiology described the beneficial effects of ketone bodies on cardiac health. According to the review, ketone bodies have been found to improve cardiac remodeling, decrease inflammation, and can improve the functioning of mitochondria (“powerhouse of the cell”) and blood vessels. Following a keto plan means more ketone bodies are delivered to the heart.

 

Keto And Heart Disease

Coronary Artery Disease (CAD) is a condition resulting from narrowing or blockage of the blood vessels that supply the heart. The blockage of vessels results from the accumulation of lipids or fat in the vessel wall, which later leads to the formation of an atheromatous plaque. When the blood supply to the heart gets compromised, it leads to chest pain or “angina.” In more severe cases, it might also lead to the death of heart tissue known as “myocardial infarction” or heart attack. 

Keto can improve the biomarkers associated with CAD. Following this way of eating is linked with lowered levels of triglycerides, improved blood sugar control, higher levels of HDL (the “good” cholesterol), and increased weight loss (in the short term), all of which can collectively lower the risk of CAD.

Despite the evidence that a ketogenic lifestyle can have a potentially beneficial effect on cardiovascular health in the short term, there are very few studies on the effect of keto on cardiac health in the long term.

 

Does Keto Cause Heart Disease?

Even though the intake of ketogenic foods is linked with a reduction in body weight and a decrease in triglyceride levels, some researchers have also reported an increase in LDL (“bad” cholesterol) with the keto diet intake. Despite improvements in other lipid markers, the increase in LDL levels associated with ketogenic foods can be a cause of concern. This is because LDL is the main source of artery-clogging fats in Coronary Artery Disease (CAD). Therefore by raising LDL levels, ketogenic food intake might potentially contribute to the development of CAD.

However, it should be kept in mind that the quality and source of fats consumed can also have implications for cardiac health. For example, a ketogenic plan primarily consisting of animal fats or processed fats might not necessarily be the healthiest of options. 

The consumption of saturated fats obtained from animal or highly processed sources has been linked with the development of CAD. There is also evidence to suggest that cutting down on saturated fat intake can help lower the risk of cardiovascular disease. 

Minimally processed plant-based fats, in general, are considered to be healthier alternatives with more data favoring their intake for better cardiovascular health. Research suggests that plant-based foods can not only reduce the incidence of the coronary artery but might also possibly reverse it. There is also a 16% lower risk of mortality from any cause with the intake of plant-based fats.

There is a concern that intake of low-carbohydrate food might lead to the development of a heart rhythm disorder. Researchers observed that the incidence of the rhythm disorder increased regardless of the dietary component used to replace carbohydrates. So, a diet low in carbs may be unsafe for long-term cardiac health.

 

Can Keto Reverse Heart Disease?

The intake of ketogenic food might also have a potential therapeutic effect on patients with heart failure. 

This is a condition in which this organ is unable to pump sufficient blood to the rest of the body. Research suggests that a failing heart relies on ketone bodies and other alternative fuels. Increasing the levels of circulating ketones in the body (either through supplements or intake of ketogenic food), may help improve the functioning of the cardiac muscle. 

Heart failure patients that were treated with infusion of ketone bodies showed significant improvement in their cardiac output. Cardiac output is the amount of blood that a heart pumps in one second, and is decreased in patients with heart failure. Therefore by improving cardiac output, ketone bodies may be used as part of the treatment for heart failure. 

Keto may also have anti-inflammatory properties (when high quality, minimally processed foods are eaten) which can be helpful for patients with cardiovascular disease. 

 

Keto And Heart Rate

When you first start a very low-carb plan, you may experience a racing heartbeat or palpitations. This is a common side effect reported by people during the first few weeks of starting this eating style. 

The symptoms usually improve over time when your body adapts to ketosis. Drinking more water can also help as palpitations could be due to dehydration.

While increased heart rate might be a benign symptom, there is a concern that keto can increase the risk of developing a rhythm disorder known as atrial fibrillation. In atrial fibrillation, the heart beats irregularly and erratically, which affects the normal pumping of the heart. This organ is unable to fill with blood and the person can experience lightheadedness or dizziness as a result. 

Other symptoms of atrial fibrillation include a racing heart, skipped beats, and mild chest pain. Atrial fibrillation is a serious condition as it can lead to stroke.

 

Is Keto Safe For Your Heart?

While the short-term benefits of this eating style are well known, unfortunately, there is a lack of evidence to support its use in the long term.

A strict ketogenic diet can also result in nutritional deficiencies which can be harmful in the long run. 

In addition, a lack of consistent adherence to the diet can cause body weight fluctuations which are harmful to cardiovascular health.17

Therefore, if you have heart disease, it might be best to consult your doctor and a dietitian before you start this way of eating. 

 

Do Cardiologists Recommend the Keto Diet?

Given the lack of conclusive evidence in favor of keto for heart health, most mainstream cardiologists do not routinely recommend this eating style. The European Society of Cardiology recommends against the intake of low-carb meals and has termed it “unsafe”.18 It should be noted that their recommendation is based on a study that observed the harmful effects of an animal-based, low-carbohydrate diet on cardiovascular health.

The American Heart Association also does not recommend following keto in its current dietary guidelines for cardiovascular health. More research is needed to study the effect of keto, particularly plant-based keto on heart health. 

 

Keto Diet For Heart Patients

Is a keto diet safe for heart patients? While there is evidence that some patients can benefit from a ketogenic diet, there are some concerns about potential side effects for cardiac patients. 

If you have heart disease, it might be best to practice caution and start keto only after consultation with your cardiologist. 

It might be a good idea to replace animal-based fats with plant-based fats in your diet. 

Some other diet tips that you can follow include:

  • Avoid red meat and heavily processed food
  • Eat plenty of fresh fruit and vegetables
  • Avoid baked and fried foods
  • Limit your salt intake
  • Choose healthy, minimally processed plant fats 
  • Drink plenty of water
  • Limit or avoid alcohol consumption

 

Keto Diet And The Arteries

The effect of ketogenic food on arteries is of much interest to researchers. There is evidence that keto can help improve serum lipid biomarkers which contribute to atherosclerosis or hardening of blood vessels and arteries. 

Atherosclerosis occurs due to the accumulation of fat cells in the blood vessel linings and is the leading cause of Coronary Artery Disease (CAD). By increasing HDL (“good” cholesterol) and decreasing triglyceride levels in the body, keto theoretically can help reduce the progression of atherosclerosis. This in turn can help lower blood pressure and reduce the risk of CAD. The protective effect of a ketogenic diet against atherosclerosis has been confirmed in a study carried out on mice.19

However, it should be kept in mind that consuming lots of saturated fats normally present in animal and processed fats can raise bad cholesterol (LDL) levels in the blood, which can increase the risk of atherosclerosis. Plant-based sources might offer the best protective effect against atherosclerosis.20

 

Keto And Chest Pain

Chest pain can either be a sign of cardiovascular disease or could be due to other non-specific non-cardiac causes. 

If cardiac chest pain occurs with exertion or activity, then it is called angina. However, if it occurs at rest, it could be a sign of more serious illness, such as myocardial infarction or heart attack. 

Theoretically speaking, as mentioned before, a ketogenic diet lowers the risk of CAD and atherosclerosis, which means you shouldn’t experience chest pains when on the diet. However, the association of low-carb food with atrial fibrillation can result in chest pains in some individuals. 

Whenever you experience any sort of unusual chest pain, immediately contact a doctor.

 

Have There Been Any Keto Heart Disease Studies?

While there have been some researches that studied the relationship between keto and heart health, there have been very few researches that studied the long-term effect of the ketogenic diet on cardiovascular health. 

Given the contradictory and conflicting nature of currently available studies, there is a need for more rigorous research on the effect of keto on heart health. 

 

Final Thoughts

Even though keto has become very popular because of its effect on short term weight loss, there is currently insufficient data to prove its positive or negative effects on cardiovascular health. 

Therefore, keto cannot be labeled as either good or bad for cardio health because the data is contradictory. It can, however, be said that the effect of keto is context-dependent. 

In certain cardiac diseases such as cardiac failure, the ketogenic diet may be very beneficial and has the potential to act as a treatment option. It may also lower the chances of developing CAD. 

However, the fact that there is a risk of atrial fibrillation and stroke with low-carbohydrate diets means that it can be risky in some individuals. 

To conclude, keto should only be used after a careful evaluation of its pros and cons and after having a discussion with your doctor.  

 

References

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  2. Kossoff EH, Turner Z, Doerrer S, et al: The ketogenic and modified Atkins diets: treatments for epilepsy and other disorders, 6 ed, New York, NY, 2016, Demos Health.
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  4. Brenton JN, Banwell B, Bergqvist AGC, Lehner-Gulotta D, Gampper L, Leytham E, et al. Pilot study of a ketogenic diet in relapsing-remitting MS. Neurol Neuroimmunol Neuroinflamm [Internet]. 2019 [cited 2022 May 3];6(4):e565. Available from Neurology.org.
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