According to this review, people with a family history of high cholesterol may also show signs of insulin resistance and therefore could benefit from following a low-carb diet. But is this controversial diet really the answer?

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For people trying to prevent heart disease and lower their cholesterol levels, the widely accepted advice for years had been to cut down on saturated fats, particularly those from animal sources and tropical oils (like palm and coconut oils). But as research evolved, we learned that refined carbohydrates (like sugar and white bread) are bigger contributors to high cholesterol than fat. In July 2020, researchers from the University of South Florida published a review in BMJ Evidence-Based Medicine, which looked at studies involving individuals with a family history of high cholesterol, and came to the conclusion that a low-carb diet may be the best way for that group to protect against the development of full-blown heart disease.

What They Found

The researchers analyzed past studies looking at the people with a family history of high cholesterol who ended up developing heart disease and noted that this subset of individuals also showed risk factors associated with insulin resistance. Eating refined carbohydrates also contributes to unhealthy cholesterol levels and heart disease risk. According to the American Heart Association, eating a high-fiber diet can help lower cholesterol levels by as much as 10%. Insulin resistance is when we first see the body having trouble effectively digesting and utilizing carbs and can lead to diabetes and cardiovascular complications if not addressed. This led the researchers to suggest that the same treatment for insulin resistance—a lower-carb diet—should be the focus for this group of individuals trying to lower cholesterol and prevent heart disease.

This review does not define exactly what type of low-carb diet they prescribe beyond mentioning the ratio of carbs to fat in one's diet. However, they do reference a study which found that carbohydrate restriction, and in particular a very-low-carb diet (also known as a ketogenic diet) was the most effective way to lower cholesterol in this population.

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Credit: Getty Images/Peter Dazeley

What It Means

Even though the review came to these conclusions, a clinical trial would need to be done to validate these assumptions. And even if the keto diet could help with high cholesterol, there could be much less restrictive methods that are more sustainable in the long run and have fewer potential risks (such as deficiencies in fiber, vitamin D, calcium and more). It is also important to note that one of the authors has paid affiliations around low-carb diets and keto.

If you are trying to lower your cholesterol, it may be worth looking at the type and amount of carbs that are in your diet rather than focusing so much on fat, especially if you are at an elevated risk for heart disease or have family history of high cholesterol. Remember, not all carbs are created equally—simple carbs, like refined grains, sweets and sugar-sweetened beverages, cause a more dramatic spike and drop in blood sugar, which can be harmful to your heart in the long term. Choose simple carbs less often and instead focus on high-fiber whole grains, which, in addition to fruits and vegetables, lean sources of protein and healthy fats and oils may help you meet your heart-health goals and can help lower cholesterol.

For more, check out our Cholesterol Diet Center.