Carotenoids are natural pigments that occur in plants and some bacteria. There are over 600 know carotenoids, several of which are commonly found in food and are important antioxidants in the body. Carotenoids fall into two classes: the carotenes, which includes beta-carotene and lycopene; and the xanthophylls, which includes lutein and its isomer, zeaxanthin. Carotenoids are what give many foods their characteristic colors; beta-carotene makes carrots and mangoes orange, lycopene makes tomatoes and watermelon red, and lutein makes the stalks of swiss chard red.

The carotenoids beta-carotene, lutein and zeaxanthin have long been associated with eye health, and lycopene is known for its potential heart and prostate benefits. New research published in the American Journal of Clinical Nutrition has found that these compounds may also improve bone health.

In the new study, researchers from Tufts University and Boston University evaluated data collected from 390 women and 213 men who participated in the Framingham Osteoporosis Study. The participants had an average age of 75 years and were followed for four years. Using food-frequency questionaires, the researchers calculated the total and individual intakes of several key caroteniods: alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, lutein and zeaxanthin. (Lutein and zeaxanthin were treated as one compound.) The researchers compared these intake levels to bone mineral density (BMD) at the hip, spine, and forearm (radial shaft) at baseline and after 4 years. The researchers polled the men and women separately, and then divided them into quartiles based on carotenoid intake, adjusting for an extensive list of variables including age, body mass index, height, physical activity index, smoking, multivitamin use, estrogen use (in women), calcium intake, vitamin D intake, and caffeine and alcohol consumption.

The researchers found that the carotenoids had different effects in women and men. In women, a higher intake of lycopene was significantly associated with higher lumbar spine BMD. In men, total carotenoids, beta-carotene, lycopene and lutein/zeaxanthin were all associated with higher hip (trochanter) BMD. The researchers concluded that "although not consistent across all BMD sites examined, these results support a protective role of carotenoids for BMD in older men and women."

In recent years, increased carotenoid intake has been associated with a number of health benefits including, skin, brain, arterial health. Learn more about lycopene and the other carotenoids here.

1. Sahni, S., M. T. Hannan, et al. (2009). "Inverse association of carotenoid intakes with 4-y change in bone mineral density in elderly men and women: the Framingham Osteoporosis Study." Am J Clin Nutr 89(1): 416-24.