Does a Low-Carb Diet Harm the Heart?

Controversy has sprung up between two major camps of researchers and nutritionists: those who view high-fat diets as harmful, and those who view high-carbohydrate diets as harmful. Everyone seems to agree that a significant portion of our diet should come from protein, with most advocating a protein intake of around 40 percent of our calories. Researchers disagree whether the rest should be predominantly fat, predominantly carbohydrate or a balance.

History

• In the 1950s, a physiologist named Ancel Keys became convinced that cholesterol levels in the blood were the greatest predictor of who would die of coronary heart disease. Since dietary fat contains cholesterol, it was assumed that dietary fat would increase blood cholesterol. Therefore, a low-fat diet would decrease cholesterol and thus would keep the heart healthy. In the 1970s when researchers began discovering that refined carbohydrates were a better predictor of heart disease, they speculated that it was the removal of natural fiber from those carbohydrates that made them so unhealthy. Thus, a high-fiber diet was thought to be heart-healthy.

Research Results

• In the 1960s, researchers discovered that the amount of total cholesterol in the blood actually has little or no relationship to heart disease. Only tiny piece of cholesterol, called VLDL (which is a piece of LDL) is correlated with heart disease. However, the amount of cholesterol in the diet does not affect the amount of cholesterol in the blood; the body makes its own. Cholesterol-lowering diets therefore do not work or help the heart.

  In 2006 a massive study of 49,000 women confirmed that increasing fiber from whole grains, fruits or vegetables had absolutely no benefit in protecting from heart disease, breast cancer, colon cancer or weight gain.

Fat Facts

• The most common objection to low-carb diets is that they are high in fat. Triglycerides are a form of fat found in both blood and fat cells. Having high blood triglycerides is a significant risk factor for developing heart disease. However, a high-fat diet has been found to actually lower triglycerides in the blood.

Carbohydrate Facts

• One major and often-overlooked factor in heart disease is the role of insulin. By constricting blood vessels, insulin raises heart rate and blood pressure. Additionally, VLDL is the single best predictor of heart disease. Both insulin and VLDL can only be raised by eating carbohydrates, particularly refined carbohydrates. They cannot be increased by eating fat.

Conclusions

• The single best predictor for heart disease that researchers have found is a high amount of refined carbohydrates in the diet. The amount of fat in the diet is not a predictor. Therefore it is unlikely that a low-carb diet will harm the heart, and very likely that it will help.