By Emily Eggleston
Tis the season of new year resolutions. Health supplements, gym memberships, and cross trainers are probably flying off the shelves as I type. Thus it is also the season to be wary of hype, particularly regarding dietary claims. This is the perfect opportunity to bring up my fragrant friend, garlic. There is a wide range of positive health claims associated with eating garlic. People have ventured that garlic might help with everything from controlling acne to fighting cancer. The laundry list of garlic health claims includes: suppressing tumor growth, promoting cardiovascular health, reducing LDL or “bad” cholesterol, and thinning blood. Many garlic advocates mention in one way or another that garlic has a very long history of culinary and medicinal use, seemingly justifying their health claims with the fact that garlic has been eaten for thousands of years. Some garlic promotion can get a bit, er, sensational. For instance one website suggests that garlic is “possibly the number one healing plant known to Man.” Here’s what a few scientists have to say about garlic:
Cardiovascular disease preventor? Maybe so.Rahman K. 2001. Historical perspective on garlic and cardiovascular disease. Journal of Nutrition. 131:977S-979S.
This is a review of the scientific studies on garlic’s ability to reduce factors contributing to cardiovascular disease. The author’s conclusion is that garlic has the potential to prevent and control cardiovascular disease. He hopes further clinical studies will be done to solidify this conclusion and also provide more data on exactly how much garlic is needed to be effective.
Cancer preventor? Possibly.
Fleishauer A et al. 2000. Garlic consumption and cancer prevention: meta-analyses of colorectal and stomach cancers. American Journal of Clinical Nutrition. Vol. 72, No. 4, 1047-1052.
This study emphasized whether the subject ate raw garlic, cooked garlic, or both and how much they consumed each week. The author’s conclusion was that eating high amounts of both every week might be associated protection against cancer. However, he mentioned that something as simple as weekly vegetable consumption could confound the results.
Fleishauer A and Arab L. 2001. Garlic and Cancer: A Critical Review of the Epidemiological Literature. Journal of Nutrition. 131:1032S-1040S.
In follow-up review of research claiming that garlic can prevent cancer, the authors are skeptical about the rigor of some studies concerning garlic. They state that the lack of variability in subjects’ garlic consumption and “poor adjustment for potential confounders” limits the quality of support for cancer fighting claims. Still, the author states that many different case studies have found high intake of garlic to have protective effects against cancer. They are enthusiastic about garlic’s ability to prevent various types of cancer, especially stomach, colon, and rectal.
Cholesterol reducer? Doubtful.
Gardner CD et al. 2007. Effect of raw garlic vs. commercial garlic supplements on plasma lipid concentrations in adults with moderate hypercholesterolemia: a randomized clinical trial. Archives of Internal Medicine. 167:346-353
This study concluded that regular consumption of raw, powdered, and aged garlic over a period of 6 months will not reduce a person’s cholesterol.
Charlson, Mary and Marcus McFerren. 2007. Garlic, what we know and what we don’t know. Archives of Internal Medicine. 167(4):325-326.
The author states that Gardner’s study is not the final word in whether garlic can reduce cholesterol, but the study’s results clearly lack significant cholesterol change for participants who consumed more garlic. However, she states that even if garlic does not lower cholesterol, it still may useful in preventing cardiovascular disease.
Blood thinner? Yes.
Its true, in concentrated amounts, garlic is a blood thinner. But this lies more in the realm of garlic supplements, not fresh or dried garlic as a food ingredient. As with any blood thinner, it is suggested that garlic supplements be avoided before surgery, giving birth or any other time when bleeding will occur. This is to avoid excessive bleeding due to thinned blood.
What does the Food and Drug Administration (FDA) say?
On the claim that garlic can improve cardiovascular health and reduce the risk of heart disease, the FDA endorses the position that “The scientific evidence about whether garlic may reduce the risk of Coronary Heart Disease (CHD) is suggestive, but not conclusive.”
The FDA confirmed the risk of excessive bleeding as a risk of garlic supplements in their 2008 publication “FDA 101: Dietary Supplements.”
It also appears, through reading numerous response letters from the FDA to marketers of garlic supplements that the supplement venders are not allowed to promote garlic as a medicine. They can speak of its health benefits but not using language that makes it sound like a drug. For example, the FDA reprimanded Vitality Products Co. for this statement on Vitality’s website: “Laboratory studies show garlic kills viruses, excellent for both high and low blood pressure, infection.”
Image credit: Garlic photo by Ian Britton