Saturday, August 13, 2011
Go to Health: Garlic
Garlic has been used by humans for over 4000 years; it originated as a wild plant in Central Asia and spread all over the world. It has been found in the tombs of Egyptian pharaohs dating back to 3200 B.C.E. Garlic is a rich source of organosulfur compounds, which are thought to be responsible for its aroma and flavor as well as its potential health benefits. Garlic has been found to inhibit bacteria, viruses and some types of fungus in the laboratory, but this has not been reliably shown in humans. Nevertheless, garlic supplements are among the best selling in the US today; I will try to explain the evidence behind its popularity as an herbal medicine. Its use in enhancing the flavor of food must be experienced: “and there was a cut of some roast…which was borne on Pegasus-wings of garlic beyond mundane speculation” C.S. Forester.
Heart Disease: Many randomized controlled trials have looked at the effect of garlic and garlic supplements on people with elevated cholesterol, LDL cholesterol and triglycerides. Some trials showed an improvement in 3 months, but no lasting effects by 6 months. However, most studies have shown that garlic supplements significantly decrease platelet clumping, which is a first step in the formation of blood clots. Because of this effect, people on blood thinners should talk to their doctors before taking garlic supplements. There is no solid evidence so far that garlic supplements reduce blood pressure or prevent the progression of plaque in the arteries, leading to heart attack or stroke. However, some studies do show benefits in these areas, and research continues.
Cancer of the stomach and colon: Studies from China, other Asian countries and Europe show that people eating raw or cooked garlic have a lower rate of cancers of the stomach, colon and rectum. However, the amount of garlic eaten, either raw or cooked, and the variable amount of vegetables also eaten made it difficult to be precise about rates of reduction, which were 30 to 50%. Aged garlic extract in high doses was also found to decrease the number of precancerous polyps in the colon. These are important benefits.
Effects of cooking: the organosulfur compounds that give garlic its beneficial effects can be inactivated by heat. The protective effects of garlic can be partially conserved by crushing or chopping garlic and letting it stand for 10 minutes before cooking. Powdered or dehydrated garlic is made from garlic cloves dried at low temperatures to prevent inactivation; the dried garlic is pulverized and made into tablets. The beneficial compounds vary greatly among commercial products – enteric coated tablets that pass the USP ‘allicin release test’ are likely to be the best. Garlic supplements are also made from fluid extracts, garlic oil and aged garlic extracts. In my opinion, the most beneficial way to use garlic for health and pleasure is to eat it raw in salad and cooked in many dishes. Follow the 10 minute rule for cooking – crush or chop garlic and let it stand for 10 minutes before cooking, to preserve its benefits.
Adverse Effects: Some people report gastrointestinal symptoms after eating garlic, some have allergic responses such as asthma, and some have skin rashes. Occasional cases of serious bleeding have been reported. However, these reactions are rare. For most of us, garlic is a strong, or subtle, delight.
There are many miracles in the world to be celebrated and, for me, garlic is the most deserving. Leo Buscaglia (the love doctor)
Sadja Greenwood, MD, MPH