Past studies have shown inconsistent results about which nutrients might be protective. Now, researchers say, the total amount and variety of fruits and vegetables may be the key to prevention.
Researchers for this new study followed more than 1,500 women, beginning on average two years after the women finished treatment for early-stage breast cancer. Initial tests confirmed that women with higher levels of carotenoids in their blood, which are markers of carotenoids in the diet, ate more vegetables and fruits.
After about seven years, women who began with the highest levels of carotenoids in their blood showed 43 percent less risk of developing breast cancer again when compared to women with the lowest carotenoid levels. Since dietary supplements can also provide carotenoids, researchers conducted a separate analysis with women whose carotenoids came only from food.
The results were the same. Carotene-containing supplements were not necessary to substantially reduce recurrence.
For quite a few years, research on the prevention of primary and recurring cancers has focused on the benefits from specific nutrients and phytochemicals, like vitamin C, beta-carotene, lycopene (a carotenoid primarily from tomatoes) and flavonoids.
Many of these substances are antioxidants, which can block or repair damaged cells that may begin the process of cancer development. Antioxidants can also affect enzymes that regulate the activation and detoxification of carcinogens in the body. In addition, they can inhibit the growth and promote the self-destruction of cancer cells.
The results of past studies on vegetable and fruit consumption and the risk of initial or recurring cancers are inconsistent, however. Some show a protective link, while others make no connection.
Part of the problem with past studies may be reliance upon self-reported vegetable and fruit intakes. People can inaccurately report what or how much they eat. The database on the content of carotenoids and other phytochemicals in foods is also incomplete. A more reliable method, which this new study uses, is measuring blood levels of carotenoids. Researchers are better able to analyze the impact of these substances because they are definitely present in the body.
Weight counts, too
Although carotenoids are primarily found in vegetables and fruits that are orange, deep yellow, dark green and red, the message of this new study is not to eat more of these specific vegetables and fruits. Since the overwhelming majority of the carotenoids in our diet come from vegetables and fruits, blood carotenoid levels indicate total vegetable and fruit consumption.
Carotenoids themselves might not be responsible for all the protection seen in this study. Vegetables and fruits that are blue, purple, light green and even white (like onions) contain other compounds that also seem protective. The implications from this study are to focus on a wide variety of produce. Make vegetables and fruits a major part of what you eat all day long.
Fruits and vegetables aren’t the only place to look for protection from the return of breast cancer. In this study, statistical analysis controlled for the impact of weight. Yet other research suggests that three factors may lower the risk of breast cancer recurrence: a healthy weight, little or no weight gain after diagnosis of your primary breast cancer and physical activity.
To lower your risk, combine these elements with a habit of eating a plentiful variety of produce for the best protection bet.
Nutrition Notes is provided by the American Institute for Cancer Research in Washington, D.C.