Garlic Fails Cholesterol Test

I love garlic, and I cook with it all the time. My awesome guacamole's secret ingredient?  Lots of garlic!! So I was bummed (though not entirely surprised) when I heard that garlic does not play a role in lowering cholesterol. 

Of the hundreds of supplements touted for their health benefits, garlic has been at the top of the list for centuries. Yet, the scientific evidence that garlic improves vitality and prevents disease is inconclusive. Stanford University researchers recently tackled the evidence for just one of the commonly claimed benefits of garlic: lower cholesterol levels.

The researchers knew that if they picked just one form of garlic, the critics would say that it was the wrong preparation. So they studied the three ways most people use garlic — in its raw form in food, garlic powder, and garlic supplements.

All 192 people studied had borderline-high LDL cholesterol. They were randomly assigned into four groups. One group ate one clove of raw garlic per day, six days a week. The garlic was mixed into sandwich spreads. Other groups received either aged or powdered garlic as a supplement. The fourth group took dummy pills. This well-designed study did not find any improvement in cholesterol levels over 6 months. Researchers designed the study to look for changes in low-density lipoprotein (LDL) cholesterol blood levels, but they tracked HDL cholesterol and triglyceride levels as well. None of the blood lipids showed any significant change.

The study participants had their blood drawn every month. LDL cholesterol levels remained quite consistent month to month. Since there was no downward trend in cholesterol, it is very unlikely that eating or taking garlic supplements for a longer period of time would have made any difference.

What does this mean to me?

When considering whether to take a dietary herb or supplement, I recommend asking yourself these questions:

• Is it safe for me?

• Are there scientific studies that support its effectiveness?

• Is this the best use of the money that I want to spend to improve my health and well-being?

Using raw garlic and garlic powder to enhance the taste of food is generally safe and can be quite tasty. Allergic reactions to garlic can occur, but they are extremely rare. Garlic supplements, however, are not safe for everyone. They can inhibit blood clotting in some people. This is usually not a problem unless you are taking other agents that inhibit clotting, such as warfarin (Coumadin), aspirin, or clopidogrel (Plavix). Higher doses of garlic also can have adverse interactions with medications. Your doctor or pharmacist can check this for you.

Even though garlic does not lower LDL cholesterol, it may help prevent heart disease and strokes in other ways. We just don't know. While some scientific studies do suggest that garlic decreases cardiovascular risks, they are small and usually flawed. Most studies do not show a consistent health benefit.

Spending your money on garlic supplements is obviously a personal choice. A strong belief that they are good for you despite the lack of scientific evidence is a type of faith, and faith and positive thinking are associated with better health outcomes.

What’s your opinion on taking supplements to improve health, be it lowering your cholesterol or something else?

Herbs and Supplements
How do herbs and supplements work? Are they safe and effective? Do they do what the label promises? The Buyer's Guide to Herbs and Supplements is a special report from Harvard Medical School that takes an expert look at many popular herbal remedies and other supplements, and provides the answers to your questions.

Julie K. Silver, M.D., is an assistant professor in the Department of Physical Medicine and Rehabilitation at Harvard Medical School. She is also the Chief Editor of Books for Harvard Health Publications.

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