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Garlic may promote
heart health without lowering blood cholesterol, however. Several
studies show that garlic can decrease clotting tendencies, thus
lowering risk of heart attack and stroke. According to the Journal
of Nutrition proceedings of a research conference on garlic, test
tube studies suggest that garlic may protect blood vessels by holding
LDL cholesterol in a less damaging form, and by blocking undesirable
changes in blood vessel walls.
Research continues
to bolster the belief that garlic may help prevent certain cancers.
An overview of several studies published in the American Journal
of Clinical Nutrition showed that garlic lowers risk of colon cancer
more than 30 percent and reduces risk of stomach cancer almost 50
percent. Several studies in recent years have also shown that substances
in garlic can reduce growth of breast and colon cancer.
Research at
Pennsylvania State University shows that compounds in garlic alter
body enzymes that activate or detoxify carcinogens, potentially
blocking cancer development in many different parts of the body.
How much garlic
is needed to receive health benefits? The answer is still not clear,
but researchers say that daily use is not needed. Studies generally
show that about five cloves of raw or cooked garlic per week is
enough to lower cancer risk 30 to 40 percent, although some studies
have shown similar drops in risk with even one clove a week.
A key point
is that the amount of active ingredients in garlic varies, depending
on how garlic is used. For example, cooking destroys one form of
the substances it contains. But, if raw garlic that has just been
chopped stands for 10 minutes before being cooked, the active compounds
formed during that period are not destroyed by heat. Garlic powder,
if used frequently and generously, may also offer some benefits,
but research is still not clear on how good a source it may be.
Use of garlic
supplements poses important questions. Supplements do not necessarily
provide larger doses of health-promoting ingredients than fresh
garlic. The main benefit of supplements is that they don't have
the flavor or odor of fresh garlic that many people don't like.
Garlic supplements
come in several forms, and different processes used to produce them
may yield products that provide very different levels of active
substances. Some studies of garlic and blood cholesterol that showed
little benefit appear to have used a garlic supplement that did
a poor job of releasing the active ingredient. Other batches of
the same brand did not have that problem. This is a reminder that,
as with all nutritional supplements, what is listed on the bottle
is not always what your body will get.
In view of
the research on different forms of garlic, use of fresh garlic in
cooking is probably the best route to the benefits garlic seems
to offer.
AICR offers the
AICR Nutrition Hotline (1-800-843-8114). Open 9 a.m. to 5 p.m. EST,
Monday-Friday, this free service allows you to ask a registered dietitian
your questions regarding diet, nutrition and cancer. AICR's Internet
Web address is www.aicr.org. The American Institute for Cancer
Research is the only major cancer charity focusing exclusively on
the link between diet, nutrition and cancer. The Institute provides
a wide range of consumer education programs that have helped millions
of Americans learn to make changes for lower cancer risk. AICR also
supports innovative research in cancer prevention and treatment at
universities, hospitals and research centers across the U.S. The Institute
has provided more than $50 million in funding for research in diet,
nutrition and cancer. |
