What form of garlic is most beneficial?

Q. Does garlic powder or pre-chopped garlic in oil protect against cancer as well as fresh garlic?

A. Garlic probably reduces risk of colorectal and stomach cancers, according to a landmark report from the American Institute for Cancer Research.

Researchers are working to understand how and which of the many substances in garlic provide the cancer protective benefits, so it is not clear whether all forms of garlic provide the same benefits or how much garlic is needed for cancer protection. Allicin and the compounds that are formed from it when the bulb is chopped or crushed, may be the substances that help in cancer protection and according to WHO about 1/4 teaspoon of garlic powder provides about the same level of allicin as one clove of fresh garlic.

The Natural Medicines Comprehensive Database, however, suggests that fresh garlic could provide significantly more allicin.

I cannot locate any information about levels of allicin in pre-chopped garlic sold in jars of oil, but one protective compound formed from allicin is fat soluble, so it may leach into the oil. If you discard the oil, you may lose some of the benefit.

Before you cook garlic, chop or press it and let it sit away from the heat for at least 10 minutes while you prepare the rest of your meal’s ingredients.

Heat prevents the protective compounds from forming, but they will form if the chopped garlic is allowed to sit for 10-15 minutes before cooking.

Q: Are there ways to reduce risk of bone cancer?

A: Cancer that begins in bone tissue is rare, accounting for less than one percent of all cancers. So far, no dietary or lifestyle choices have been linked to increasing or decreasing risk of these cancers.

Cancer in bones is more commonly a cancer from other tissue, such as breast, lung or prostate that has spread to the bones.

A vital area of research involves searching for how treatments and lifestyle choices might slow down the growth of cancer throughout the body so that it can be treated before it spreads, and to decrease a tumor’s ability to spread to bone and other tissues.

Lab studies suggest that physical activity, the omega-3 fats in naturally fatty fish, and certain compounds in green tea, garlic and other vegetables might help toward this goal, but I am not aware of studies that support those findings in humans.

We have much to learn before any specific recommendations could be made.

While research progresses in seeking to understand the rare cancer that originates in bone, the best way to reduce risk of the more common cancer in bones — cancer spread from elsewhere in the body — is to follow the lifestyle that reduces risk of cancer overall.

That means avoiding tobacco; being physically active every day; maintaining a healthy weight; and eating a balanced diet that includes a wide variety of vegetables, fruits, whole grains and beans.

Ÿ Provided by the American Institute for Cancer Research. Learn more about the group and its New American Plate program at aicr.org.

Although bone cancer does not have a clearly defined cause, one type occurs more frequently in people, especially children, who have had treatment with high-dose radiation or certain anticancer drugs. Yet other types are not linked with any particular factor.