How Do Plants Help Prevent Cancer?

Enlarge Image Image Gallery Cancer-prevention allies. Clockwise from top: turmeric, cabbage, garlic, licorice, aloe, and ginseng.

It’s hard to turn a magazine or newspaper page without finding a new study that touts a plant’s ability to help prevent or treat cancer. But clinical trials show that only a handful of plant products successfully do so. Why this disparity? Do herbs and foods help, or don’t they?

The answer is yes, they can. But the plants that help prevent cancer don’t necessarily help treat it. In fact, from a scientific standpoint, the methods for herbally preventing and treating cancer are nearly diametrically opposed.

Some herbalists would disagree with this statement, saying that effective treatment involves the whole person and that therapies such as boosting the immune system and detoxification are, in fact, primary—it’s thought that cancer cannot flourish in a healthy, balanced, and well-nourished system. Herbal remedies have certainly helped support immune systems, prolong life, and improve the quality of life in some cases.

For the most part, however, this sort of treatment is still theoretical or the existing research is still preliminary. When dealing with cancer, it’s important to be able to sort out what the research supports and what is a more experimental approach. So, for the purposes of this article, “treating cancer” means directly reducing tumor growth. Other benefits, such as boosting the immune system, we will call “adjunct” therapy.

Here’s our guide for helping you sort out fact from fiction and established science from theory.

Preventing cancer

Cancer prevention is the strong point of herbs and functional foods. Literally thousands of plant-derived products are associated with a lower risk for most types of cancer when used throughout your lifetime. These “associations” come from epidemiological studies, which rate the relationship between the risk of various cancers and the level of long-term consumption of a certain plant. This type of study gives clues about which foods and/or supplements one can use over many years to help prevent cancer. Here are some of the ways plants can keep you healthy. (See the chart on page 58 for some examples from each category.)

Prevent mutations. The major initial cause of cancer is mutations of our genetic material, DNA. Toxic or highly reactive chemical compounds can bond directly to DNA, changing and possibly damaging its structure. When a cell divides, the altered DNA copies itself, and this “mutation error” is reproduced in the new cells. These new cells now have a different DNA sequence than the parent cells did.

DNA mutation happens thousands of times a day in a typical human body. Almost always, the body destroys the mutations ­before they do any harm. But occasional mutations survive, with the ability to direct cells to grow out of control—and this is the beginning of cancer.