Alpha- and Beta-Carotene Linked to Lower Breast Cancer Risk
Adding to the evidence for benefits from fruits and veggies.
A dietary pattern high in vegetables and fruits such as carrots, pumpkin, sweet potatoes, peppers, cantaloupe and dark leafy greens might help protect you against breast cancer. According to a new analysis of data from the European Prospective Investigation into Cancer and Nutrition study, women with higher blood levels of alpha- and beta-carotene were significantly less likely to have breast cancer.
"Blood levels of these carotenoids are likely serving as markers of food choices that these women are making," says Elizabeth J. Johnson, PhD, a scientist in Tufts' HNRCA Antioxidants Research Laboratory who specializes in vitamin A and carotenoid compounds. "While there is evidence that alpha- and beta-carotene may have anti-carcinogenic effects, it is more likely that a dietary pattern high in vegetables and fruits provides benefit."
INVERSE ASSOCIATION: The study, published in the American Journal of Clinical Nutrition, compared 1,502 breast-cancer patients with an equal number of healthy women matched for possible confounding factors. Blood samples were used to measure levels of carotenoids, vitamin A (retinol), vitamin C and vitamin E (tocopherol). Comparing the highest versus the lowest one-fifth, levels of alpha-carotene (39% lower) and beta-carotene (59% lower) were inversely associated with breast cancer incidence. The association was limited to estrogen receptor-negative tumors, and no statistically significant associations were found for vitamins A, C or E.
The results echo a 2012 meta-analysis of eight studies that concluded women with higher blood levels of carotenoids may be at reduced risk of breast cancer. Other research has suggested dietary patterns high in carotenoids could also help protect your heart: A 10-year Dutch study published in 2011, for example, linked consumption of deep-orange fruits and vegetables to a lower risk of coronary heart disease
KNOW YOUR CAROTENOIDS: Carotenoids are yellow, orange and red pigments synthesized by plants; in addition to foods of those colors, they are also found in dark leafy greens such as spinach and kale and green veggies like broccoli and peas. Your body can convert alpha- and beta-carotene and beta-cryptoxanthin into vitamin A, so these are called "provitamin A carotenoids." Other carotenoids include lutein, zeaxanthin and lycopene. Although they do not have vitamin A activity, these have other biological functions that may be important for optimal health.
The study's authors caution that the results don’t necessarily mean that it helps to take dietary supplements of alpha- and beta-carotene. Pills don’t deliver the dietary fiber, phytonutrients and other vitamins and minerals found in vegetables and fruits, and high-dose beta-carotene supplements (beyond what is possible from dietary sources) were found to actually increase lung-cancer risk in smokers.
Instead, Tufts' Johnson advises, get your carotenoids from the many delicious dietary sources. (See box.) To get the most carotenoids from your food, chop or even purée your fruits and veggies to increase bioavailability, which is also improved by cooking. Because these are fat-soluble nutrients, they are best consumed along with some healthy unsaturated fats - cooked in vegetable oil or tossed with a little oil in a salad.
TO LEARN MORE: American Journal of Clinical Nutrition, February 2016 -