A new study provides evidence that certain nutrients found in vegetables may help protect against breast cancer. Women with high blood levels of several different carotenoid substances faced up to two times lower breast cancer risk than women with low levels, according to a new study published in the American Journal of Epidemiology.

Perhaps the most well known of these substances is beta-carotene, found in deep green and orange vegetables and fruits, like broccoli, carrots and cantaloupe. Other members of the carotenoid family that were significant include lutein (in kale, spinach and other cooked greens), alpha-carotene (in carrots and pumpkin) and beta-cryptoxanthin (in oranges, peaches and papayas).

ANTIOXIDANT POWER

These links between carotenoids and reduced breast cancer risk make sense in light of past studies that show these substances are antioxidants and help regulate cell growth, gene expression and immune responses. Many population studies indicate lower incidence of cancer with greater carotenoid consumption and higher blood levels.

Although carotenoid levels appear linked to lower cancer incidence, a major report on diet and cancer risk from the American Institute for Cancer Research (AICR) notes that other substances in these foods may also provide important protection.

FOOD VARIETY IS KEY

Researchers at the University of California are investigating whether diet can decrease the chance of breast cancer recurrence. They note that the diet on which blood levels of carotenoids increased contained a wide variety of plant foods. It included five servings of vegetables, three of fruit, and two cups of vegetable juice each day. The diet was also high in fibre and low in fat.

It may be difficult to determine, then, which aspect of the diet may be responsible for the protection. Some research suggests that the overall diet pattern is more significant to cancer risk than consumption of any individual foods.

AICR estimates that, while carotenoids possibly decrease breast cancer risk, increased overall fruit and vegetable consumption can prevent an estimated 10% to 20% of breast cancer cases.

“Nutrition Notes” is provided as a public service by the American Institute for Cancer Research, 1759 R Street, NW, Washington, DC 20009