More than just a wonderful seasoning - touted to help lower cholesterol and blood pressure - does it work??? Fresh garlic releases the enzyme allinase when cut or crushed which interacts with alliin to produce allicin, which produces the typical odor and taste of garlic. Allinase is fragile and breaks down after 15 minutes of cooking at high heat or several hours at room temperature. Crushing with oil produces more stable ajoene or dithiins and may be stable for a year. Allicin is the active ingredient thought to have medicinal qualities. It is also bactericidal in vitro.
Studies: These are difficult due to the volatility of the active compound, but the majority have used dried garlic powder tablets. The average dose equals 1/2 - 1 whole clove worth of fresh garlic. A 1993 Meta-analysis study including 410 patients showed a 9% reduction in total cholesterol in the garlic treated subjects. The studies included varied by garlic preparation used and were not well controlled. Other studies are positive, but not strongly so, others show no positive benefit. No negative studies have been published. The biggest factor among studies seems to be the variability of the Garlic type and quantity used.
Common Doses: Garlic powder tablets (Kwai) typically have 300 mg. of coated fresh freeze dried garlic. These are taken 2 -3 times a day with meals. The coating is dissolved in the intestine and then allinase converts the alliin to active allicin. The tablets are odorless until ingested - some people notice a garlic taste or odor, but that is a sign of it functioning. Be cautious - deodorized tablets and some others contain no allicin - the active ingredient!!
Side Effects: Usually only taste and odor. The raw clove can cause gas, upset stomach, and reflux of acid. Garlic has a mild blood thinning effect so caution is advised for people on blood thinners - consult your physician and monitor this closely!
Summary: Use only the fresh stuff - but the final word is still out and awaiting more studies - we need longer term ones with more participants that are more carefully designed and use a standardized form of garlic so comparisons can be drawn.
Garlic should be used as an adjunct to a healthy diet, exercise, and weight loss and any medication if needed. It is not sufficiently effective to replace medications by itself. Talk to your physician and work together as a team to improve your health!
References:
- Berthold HK, et al. Effects of a garlic oil preparation on serum lipoproteins and cholesterol metabolism. A randomized controlled trial. JAMA 1998;279:1900-1902.
- Gebhardt R. Multipl Inhibitory effects of garlic extracts on cholesterol biosynthesis in hepatocytes. Lipids 1993;28:613-619.
- Isaacsohn JL, et al. Garlic powder and plasma lipids and lipoproteins. A multicenter, randomized, placebo controlled trial. Arch Intern Med 1998;158:1189-1194.
- Jain AK, et al. Can Garlic reduce levels of serum lipids? A controlled clinical study. Am J Med 1993;94: 632-635.
- Neil HA, et al.Garlic powder in the treatment of moderate hyperlipidemia: a controlled trial and meta-analysis. J Royal Coll Phys London 1996;30:329-334.
- Simons LA, et al. On the effect of garlic on plasma lipids and lipoproteins in mild hypercholesterolemia. Atherosclerosis 1995;113:219-225.
- Warshafsky S, et al. Effect of garlic on total serum cholesterol. A meta-analysis. Ann Intern Med 1993;119:599-605.