Heart Attack and Garlic

Garlic is a time-tested remedy that has also been studied for numerous health benefits, from killing fungi to helping control blood sugar. For people who have had heart attacks, supplementing with garlic may prevent recurring heart attacks and increase survival rates.

Note: People who take aspirin to prevent heart attacks should not take garlic supplements, as the combination could lead to excessive bleeding.

Garlic may have a number of benefits for the heart, though specific effects are not clear. It may help prevent heart attacks by acting as a blood thinner.^15-18,112 Garlic may also help reduce high cholesterol and high blood pressure.

Read more details about Garlic.

In one study, 432 people who had suffered a heart attack were given either garlic oil extract or no treatment over a period of 3 years.⁸ The results showed a significant reduction of second heart attacks and about a 50% reduction in death rate among those taking garlic.

Garlic can be taken in many forms: fresh; cooked; aged, or preserved; as a powder, perhaps in capsules; and in an extract form, also in capsules. The garlic used in the study discussed here was garlic oil extract. A typical dosage of garlic is 900 mg daily of a garlic powder extract standardized to contain 1.3% alliin, providing about 12,000 mcg of alliin daily, or 4-5 mg of “allicin potential.” Alliin-free aged garlic is taken at a dose of 1 to 7.2 g daily.

Garlic supplements of various forms can be found in health food stores and drug stores. Products vary in quality, primarily because some of garlic's active components can deteriorate as a result of processing.

Alliin is a relatively odorless substance found in garlic. When garlic is crushed or cut, an enzyme called allinase is brought in contact with alliin, turning it into allicin. Allicin is responsible for much of the typical odor of garlic. It is very active chemically and probably helps the garlic bulb defend itself from attack by insects and other threats. However, allicin is unstable, and soon breaks down into a variety of other substances. When garlic is ground up and encapsulated, the effect is similar to cutting the bulb: Alliin contacts allinase, yielding allicin, which then breaks down. Unless something is done to prevent this process, garlic powder won't have any alliin or allicin left by the time it is purchased.

Some garlic producers believe that alliin and allicin are not essential for garlic's effectiveness and do not worry about this. Aged garlic, for example, has very little of either compound. But other manufacturers believe that allicin is the primary active ingredient in garlic. Because allicin is an unstable chemical, these manufacturers are faced with a challenge.

One solution might be to chemically stabilize allicin so that it doesn’t break down. However, allicin has a strong garlic smell, and a relatively odorless product is preferable. Many manufacturers of garlic powder products seek to stabilize the alliin in the product, and to do so in such a way that the alliin converts to allicin after it is consumed. How well their methods work remain a matter of controversy.

Note: Do not confuse essential oil of garlic with garlic oils. The term "garlic oil" refers to garlic extracted by means of oil. Garlic essential oil is the pure oily component of the herb, and, like other essential oils, it is not intended for oral consumption and is potentially toxic.

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Safety Issues

As a commonly used food, garlic is on the FDA's GRAS (generally recognized as safe) list. Rats have been fed gigantic doses of aged garlic (2,000 mg per kilogram body weight) for 6 months without any signs of negative effects. ¹ Long-term treatment with standardized garlic powder at a dose equivalent to three times the usual dose, along with fish oil, produced no toxic effects in rats. ² The only common side effect of garlic is unpleasant breath odor. Even "odorless garlic" produces an offensive smell in up to 50% of those who use it. ³ Other side effects occur only rarely. For example, a study that followed 1,997 people who were given a normal dose of deodorized garlic daily over a 16-week period showed a 6% incidence of nausea, a 1.3% incidence of dizziness on standing (perhaps a sign of low blood pressure), and a 1.1% incidence of allergic reactions. ⁴ There were also a few reports of bloating, headaches, sweating, and dizziness.

When raw garlic is taken in excessive doses, it can cause numerous symptoms, such as stomach upset, heartburn, nausea, vomiting, diarrhea, flatulence, facial flushing, rapid pulse, and insomnia.

Topical garlic can cause skin irritation, blistering, and even third-degree burns, so be very careful about applying garlic directly to the skin. ⁵ Since garlic might "thin" the blood, it is probably imprudent to take garlic pills immediately prior to or after surgery or labor and delivery, because of the risk of excessive bleeding. ⁶ Similarly, garlic should not be combined with blood-thinning drugs, such as warfarin (Coumadin), heparin , aspirin , clopidogrel (Plavix), ticlopidine (Ticlid), or pentoxifylline (Trental). In addition, garlic could conceivably interact with natural products with blood-thinning properties, such as ginkgo , policosanol , or high-dose vitamin E . However, a placebo-controlled study found that actual raw garlic consumed in food at the fairly high dose of 4.2 mg once daily did not impair platelet function. In addition, volunteers who continued to consume the dietary garlic for a week did not show any change in their normal platelet function. ⁷ Garlic may also combine poorly with certain HIV medications. Two people with HIV experienced severe gastrointestinal toxicity from the HIV drug ritonavir after taking garlic supplements. ⁸ Garlic might also reduce the effectiveness of some drugs used for HIV. ⁹ Garlic is presumed to be safe for pregnant women (except just before and immediately after delivery) and nursing mothers, although this has not been proven.

Interactions You Should Know About

If you are taking:

• Blood-thinning drugs such as warfarin (Coumadin), heparin, aspirin, clopidogrel (Plavix), ticlopidine (Ticlid), or pentoxifylline (Trental): Do not use garlic except on medical advice.

• Ginkgo , policosanol , or high-dose vitamin E : Taking garlic at the same time might conceivably cause a risk of bleeding problems.

• Medications for HIV : Do not use garlic.

1. Sumiyoshi H, Kanezawa A, Masamoto K, et al. Chronic toxicity test of garlic extract in rats [in Japanese; English abstract]. J Toxicol Sci. 1984;9:61-75.
2. Morcos NC, Camilo K. Acute and chronic toxicity study of fish oil and garlic combination. Int J Vitam Nutr Res. 71(5):306-12.
3. Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physicians' Guide to Herbal Medicine. 3rd ed. Berlin, Germany: Springer-Verlag; 1998:121.
4. Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physicians' Guide to Herbal Medicine. 3rd ed. Berlin, Germany: Springer-Verlag; 1998:121.
5. Garty BZ. Garlic burns. Pediatrics. 91(3):658-9.
6. Burnham BE. Garlic as a possible risk for postoperative bleeding. Plast Reconstr Surg. 95(1):213.
7. Scharbert G, Kalb ML, Duris M, et al. Garlic at dietary doses does not impair platelet function. Anesth Analg. 2007;105:1214-1218
8. Piscitelli SC. Use of complementary medicines by patients with HIV: Full sail into uncharted waters. Medscape HIV/AIDS. 2000;6.
9. Piscitelli SC, Burstein AH, Welden N, Gallicano KD, Falloon J. The effect of garlic supplements on the pharmacokinetics of saquinavir. Clin Infect Dis. 34(2):234-8.

8. Bordia A. Garlic and coronary heart disease. The effects of garlic extract therapy over three years on the reinfarction and mortality rate [translated from German]. Dtsch Apoth Ztg. 1989;129(Suppl 15):16-17.
15. Legnani C, Frascaro M, Guazzaloca G, et al. Effects of a dried garlic preparation on fibrinolysis and platelet aggregation in healthy subjects. Arzneimittelforschung. 1993;43:119-122.
16. Chutani SK, Bordia A. The effect of fried versus raw garlic on fibrinolytic activity in man. Atherosclerosis. 1981;38:417-421.
17. Kiesewetter H, Jung F, Pindur G, et al. Effect of garlic on thrombocyte aggregation, microcirculation, and other risk factors. Int J Clin Pharmacol Ther Toxicol. 1991;29:151-155.
18. Reuter HD, Sendl A. Allium sativum and Allium ursinum: Chemistry, pharmacology and medicinal applications. Econ Med Plant Res. 1994;6:56-113.
120. Ried K, Frank OR, Stocks NP, et al. Effect of garlic on blood pressure: a systematic review and meta-analysis. BMC Cardiovasc Disord. 2008 Jun 16.
121. Khoo YS, Aziz Z. Garlic supplementation and serum cholesterol: a meta-analysis. J Clin Pharm Ther. 2009;34:133-45.