A low-carb diet is an effective alternative to traditional low-fat, low-calorie diets. However, many individuals worry about the potential cardiovascular problems a diet higher in saturated fats may cause. Critics of the Atkins diet say low-carb diets raise cholesterol levels, especially LDL (low-density lipoprotein), increasing the risk for heart disease. Studies and articles published in scientific journals over the past decade state otherwise.
Atkins Diet and LDL Cholesterol: LDL Particle Size Increases on Low Carb Diets
In a study published by The American Journal of Clinical Nutrition, Ronald M. Krauss and others investigated the effects of dietary saturated fats on blood lipids in connection with various levels of carbohydrate restriction. The study included 178 obese men divided into groups that ate 54%, 39%, or 26% of their daily calories from carbohydrate and 7% to 9% from saturated fats. A fourth group ate 26% of their daily calories from carbohydrate and 15% from saturated fats.
Overall, total LDL reduction was greater on the 54% carbohydrate, low-saturated fat diet. However, the lack of reduction in the higher-fat 26% carbohydrate diet came from the type of lipoprotein changes experienced. Those who ate higher saturated fat replaced small, dense LDL cholesterol with large, fluffy LDL particles, so their total LDL levels didn’t change much.
Total LDL Levels Mislead: Small, Dense Particle Size vs Large LDL Particles
LDL lipoproteins transport cholesterol to body tissues for use by the cells. Their job is essential. However, LDL damaged by oxidation or glycated by blood sugar deposits their cholesterol into artery walls, where it doesn’t belong. According to Michael R. Eades, M.D., author of The Protein Power Lifeplan, looking at just LDL levels is misleading because only damaged lipoproteins promote the development of cardiovascular disease.
Small, dense LDL particles are easily oxidized and damaged. Large, fluffy LDL particles resist oxidation and are less likely to cause cardiovascular problems. According to Krauss, high-carbohydrate, low-fat diets increase concentrations of small, dense LDL particles, while those on a higher-fat, low-carbohydrate diet produce large LDL particles, the type that resist oxidation and glycation.
Eades also writes about the strong connection between triglyceride level and large, fluffy LDL particles. When triglycerides rise, the body makes small, dense LDL particles; when triglycerides fall, the body makes larger diameter particles. Therefore, knowing a person’s triglyceride level points to the type of LDL cholesterol manufactured by the liver; a low triglyceride level suggests a lower cardiovascular risk.
Do Cholesterol Levels Matter? What Causes Elevated Triglycerides?
The total cholesterol number is made up of low-density and high-density lipoproteins, triglycerides, and Lp(a) cholesterol. So when HDL levels rise, total cholesterol levels might appear to not improve. HDL carries cholesterol away from the arteries and back to the liver for elimination from the body. Higher levels of HDL are helpful. In fact, some believe that HDL removes excess cholesterol from arterial plaque, slowing its buildup.
The American Heart Association says a high-carbohydrate diet causes elevated triglycerides, as well as overweight and obesity, inactivity, smoking, and excess alcohol consumption. Therefore, replacing fat in the diet with more carbohydrate will worsen blood lipid levels, rather than improve them. According to Krauss, this includes saturated fats as well. A low-carbohydrate diet improves HDL transport, and thereby drastically lowers elevated triglycerides.
Atkins Diet Improves Cholesterol Levels and LDL Particle Size
Because of its effect on insulin levels, a low-carbohydrate diet is often used to correct metabolic disorders. However, many voice concern over potential cardiovascular risk due to the increased saturated fat. Studies and meta-analysis articles have shown low-carbohydrate diets to be a viable option in the treatment of obesity, as well as the improvement of cardiac markers.
A low-carbohydrate diet raises high-density lipoproteins which remove cholesterol from artery buildup and transports it back to the liver for removal from the body. While low carbohydrates do not always reduce low-density lipoproteins as a whole, the Atkins diet supports the production of large, fluffy LDL particles, rather than the small, dense particle size often produced by the liver when carbohydrates are high.
For further information on the roles of artery injury, LDL cholesterol damage, plaque build up, and insulin resistance in the process of heart disease, see Damaged LDL Cholesterol Sets the Stage for Heart Disease.
References:
The American Journal of Clinical Nutrition, Krauss, Ronald M. et al, “Separate effects of reduced carbohydrate intake and weight loss on atherogenic dyslipidemia,” 83:5, 1025-1031, May 2006.
Nutrition & Metabolism, Feinman, Richard D. and Volek, Jeff S., “Low carbohydrate diets improve atherogenic dyslipidemia even in the absence of weight loss,” 3:24, June 2006; doi:10.1186/1743-7075-3-24.
Eades, Michael R., M.D. and Eades, Mary Dan, M.D., The Protein Power Lifeplan: A New Comprehensive Blueprint for Optimal Health, Warner Books, 2000.
American Heart Association, heart.org, “ Good vs. Bad Cholesterol ” (accessed July 26, 2010)
Vickie Ewell - Vickie has worked with autistic individuals for 9 years. She has celiac disease and specializes in gfcf living.
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