Twenty years ago, it seemed as if only athletes and health fanatics understood the relationship between low cholesterol and good health. Today, many of us are as familiar with our cholesterol count as we are with our Social Security number, and some of us have had to face the daunting task of watching our cholesterol intake.
About 30 percent of Americans have blood cholesterol levels elevated enough to warrant changes in lifestyle and diet. Another 7 percent have levels so high that they must take medication ranging from aspirin to estrogen-replacement therapy. These treatments can have unwanted side effects, and some are quite expensive. According to researchers at the Veterans Affairs Medical Center in San Francisco, however, six to eight million people could use alternative treatments, including lifestyle changes, that would save them $3 to $4 billion a year in drug costs. Scientists are discovering and documenting that garlic packs a powerful punch in the fight against high cholesterol and heart disease.
The Culprit
The human body requires cholesterol to build cell walls and manufacture vital substances such as vitamin D and hormones, and the liver makes all that we require for normal cell functions. Dietary cholesterol is a fatty substance found in foods of animal origin such as beef, poultry, fish, eggs, and dairy products. After it is consumed, it combines with proteins to form particles called lipoproteins, which carry it through the bloodstream. High levels of low-density lipoproteins (LDL), commonly called “bad” cholesterol, can cause cholesterol to be deposited as plaque on artery walls, diminishing blood flow and increasing the likelihood of blood clots, which can cause heart attack or stroke. High-density lipoproteins (HDL), or “good cholesterol”, on the other hand, scavenge cholesterol from the bloodstream and carry it to the liver for excretion.
The ratio of LDL to HDL is an indication of related health risks: an adult with an LDL level above 160 milligrams per deciliter (mg/dl) of blood and an HDL level below 35 mg/dl is five times as likely to develop coronary artery disease (a buildup of plaque in the arteries) as an individual with an LDL level of 160 or below and an HDL level 35 or higher.
Garlic’s Role
Garlic (Allium sativum), either fresh cloves or standardized garlic preparations, can lower LDL levels. Studies have shown that people who regularly consume relatively large amounts of garlic and onions have lower cholesterol levels than people who don’t.
Laboratory studies published in 1933 showed that artificially induced arteriosclerosis (hardening of the arteries) in animals was reduced when they were fed fresh pressed garlic juice and garlic extracts. Dozens of subsequent studies have suggested that eating one to two average-sized cloves of garlic a day reduces serum cholesterol by inhibiting cholesterol absorption.
When a clove of garlic is crushed or sliced, the compound alliin and the enzyme allinase are released. Together, they react to form allicin–the main sulfur compound responsible for garlic’s health benefits.
Clinical Studies
At least forty clinical studies have measured the effect of garlic preparations on total cholesterol. Most have involved tablets standardized to allicin. Treatments lasted from three weeks to ten months. On average, cholesterol levels decreased 10.6 percent.
Twenty-eight additional clinical studies involving patients with high levels of fats in their blood, high cholesterol, hypertension, coronary heart disease, and clogged arteries showed similar results. Participants had an average 10.3 percent decrease in cholesterol levels. A researcher who recently reviewed these studies concluded that a daily dose of 600 to 900 mg of garlic powder, containing 0.6 percent of allicin, can decrease blood lipid levels, decrease LDL cholesterol, and increase HDL.
Cloves or Tablets?
In seven of the forty studies referred to above, 3 to 10 g of fresh garlic per day decreased cholesterol levels by an average of 16 percent in the 301 subjects. In thirteen of the studies, 600 to 900 mg of garlic tablets a day decreased cholesterol levels by an average of 10.3 percent in 427 participants. In ten other studies, standardized garlic tablets decreased cholesterol levels by an average of 12.9 percent in 4,179 individuals. Although eating fresh garlic may reduce LDL levels to a greater degree, standardized garlic tablets are both effective and convenient, and they don’t carry the risk of stomach upset or garlic breath. Whatever form of garlic you choose, you won’t go wrong.
Monitoring Your Cholesterol Levels
Your health-care provider can check your blood cholesterol levels and advise you on proper treatment if necessary. You can also call the American Heart Association at (800) 242-8721 for information on low-cost or free cholesterol screenings in your area. Although age, hormone levels, heredity, and whether you smoke or have high blood pressure all contribute to your risk of developing heart disease, guidelines provided by the American Heart Association can be used as a general measure of cardiovascular health.
Total Blood Cholesterol
Desirable: 199 milligrams per deciliter of blood or less
Borderline: 200 to 239 mg/dl
High: 240 mg/dl or higher
LDL Cholesterol
Desirable: 129 mg/dl or less
Borderline: 130 to 159 mg/dl
High: 160 mg/dl or higher
HDL Cholesterol
Low (increased risk of heart disease): 34 mg/dl or less
High (decreased risk of heart disease): 60 mg/dl or higher
If your total blood cholesterol is higher than desirable, consider making changes in your diet and lifestyle. Cut fats to no more than 30 percent of your total calories, and saturated fats to 10 percent or less; eat foods rich in fiber such as oats and many fruits and vegetables; limit cholesterol intake to no more than 300 mg daily. Control your weight with regular exercise. Quit smoking.
Additional Reading
• Avins, A. L., and W. S. Browner. “Lowering Risk without Lowering Cholesterol: Implications for National Cholesterol Policy”. Annals of Internal Medicine 1996, 125(6):502-506.
• Gaziano, J. M., P. R. Hebert, and C. H. Hennekens. “Cholesterol Reduction: Weighing the Benefits and Risks”. Annals of Internal Medicine 1996, 124(10): 914-918.
• Kleijnen, J., et al. “Garlic, Onions and Cardiovascular Risk Factors. A Review of the Evidence from Human Experiments with Emphasis on Commercially Available Preparations”. British Journal of Clinical Pharmacology 1989, 28:535- 544.
• Koch, H. P., and L. D. Lawson, eds. Garlic: The Science and Therapeutic Application of Allium sativum and Related Species. 2nd ed. Baltimore: Williams and Wilkins, 1996.
• Murray, M., and J. Pizzorno. Encyclopedia of Natural Medicine. Rocklin, California: Prima, 1990.
• Reuter, H. D. “Allium sativum and Allium ursinum: Part 2. Pharmacology and Medicinal Application”. Phytomedicine 1995, 2(1):73-91.
• Warshafsky, S., et al. “Effect of Garlic on Total Serum Cholesterol”. Annals of Internal Medicine 1993, 119:599-605.
• Wise, G. R., and T. T. Schultz. “Hyperlipidemia. When Does Treatment Make a Difference?” Postgraduate Medicine 1996, 100(1):138-149.
