High-density lipoprotein or HDL is the body's way of transporting excess fats to the liver for storage and disposal. For this reason, doctors and patients often call HDL the "good cholesterol."
National Institutes of Health guidelines encourage men over age 20 to maintain an HDL level no lower than 40 mg per deciliter, or 1/10th of a liter, and women to aim for 50 mg per deciliter. Below these levels, HDL can not perform the protective function adequately.
Dietary Causes
In the February 2004 issue of "The Journal of Clinical Nutrition," a team of researchers reported that "a diet very low in carbohydrates was more effective than a low fat diet in elevating HDL levels and affecting weight loss." This supports the theory that HDL production occurs in response to a minimal amount of fat in the diet. When simple carbohydrates, such as soda, pasta, white bread and white rice, dominate the diet, the body loses the natural stimulus to build a healthy level of HDL. NIH Guidelines cite a diet with more than 60 percent of its calories coming from carbohydrates as a cause of low HDL.
Heavily linked to the dietary causes of low HDL is obesity, defined as a body mass index of 30 or greater. On Feb. 1, 2000, Dr. Margo Drake, of the Baylor College of Medicine, reported in "Lipids On Line" that for every 7 lb of weight loss, HDL-C levels increased 1 mg/dL after the subject maintained weight reduction for six weeks, giving physicians evidence that obesity is directly related to low HDL levels.
When comparing food choices with obesity as causes of low HDL, it is impossible to determine which may be more important. Too often they act in concert. But neither is this difference important in making choices about how to prevent low HDL. Eating a diet that minimizes carbohydrates, and emphases healthy fats, such as those found in walnuts, olive oil, flax seed, avocados and fish, is recommended by NIH as a strategy both for weight loss and for the prevention of low HDL.
Lifestyle Causes
Alcohol has been maligned as a source of empty calories, but ounce for ounce, it may be the most effective food for preventing low HDL, according to researchers in England. Abstinence from alcohol deprives the body of one of the most effective ways of creating a healthy level of HDL. Conversely, a moderate amount of alcohol benefits most adults. Specifically, "Drinking one ounce of alcohol each day increases the HDL level by 4 mg per deciliter," Professor E.B. Rimm and his colleagues wrote in the May 1999 issue of "The British Medical Journal." This benefit tops out at a 4-oz. single daily serving, with wine or beer offering the greatest benefit per calorie.
While as having a small glass of wine raises HDL and protects the heart from the effects of harmful forms of cholesterol, smoking lowers HDL. Doctors at the University of Kyoto wrote in the October 2003 issue of "Preventative Medicine" that smoking cessation increased HDL by 1 mg per deciliter in the patients they studied.
The National Institutes of Health lists smoking as a cause of low HDL without stating a length of smoking history or a cigarettes-per-day minimum. The NIH also does not say whether second-hand smoke may contribute to low HDL.
.
Medication Causes
Medications that can cause or exacerbate low HDL levels include prescription testosterone and other forms of androgens or male sex hormones. Beta blockers, anabolic steroids, excessive zinc supplements and progestin cause the same effect.
When the benefit of one of these medications outweighs the risk, modifying the diet, engaging in smoking cessation and adding exercise to the daily routine are sensible ways to help counter the lowering of the HDL level. Researchers at the National Institutes of Health recommend testing HDL every three to 12 months while taking a medication in this category.
References
- National Institutes of Health: National Cholesterol Education Program; Third Report of the Detection,Evaluation and Treatment of High Blood Cholesterol in Adults
- "American Journal of Clinical Nutrition"; Effects of Moderate-fat (from Monounsaturated Fat) and Low-fat Weight-loss Diets on the Serum Lipid Profile in Overweight and Obese Men and Women; C.L. Pelkman, et al; February,2004
- Baylor College of Medicine: Lipids on Line: Effects of Lifestyle and Dietary Modification on HDL-C Levels; Margo A. Denke, M.D.; February 2001
- "British Medical Journal"; Moderate Alcohol Intake and Lower Risk of Coronary Heart Disease: Meta-analysis of Effects on Lipids and Haemostaticfactors; E.B. Rimm, P. Williams, K. Fosher, M. Criqui; May 1999 (abstract)
- American Academy of Pediatrics: 2007 Guidelines fo Management of Lipid Sceening in Children
