Higher levels of carotenoids may reduce breast cancer risk

At a Glance

The results of a new large study indicate that women with higher plasma carotenoid levels have a reduced risk of breast cancer, and particularly the more aggressive tumors.

 Read more about this research below.

Carotenoids are among the nutrients needed for plant photosynthesis.  They are also the pigments in fruits and vegetables that provide  the yellow, orange and red colors. Of over 600 known dietary carotenoids, a-carotene, b-carotene, b-cryptoxanthin, lutein, zeaxanthin, and lycopene are the most prevalent in the US diet, comprising 90% of circulating carotenoids.  Current evidence suggests that carotenoids may reduce breast cancer risk, but at what stage they are most influential and in what tumor subtypes is less clear. 

In a recent large study published online in the American Journal of Clinical Nutrition, researchers examined the issues of timing of carotenoid exposure as well as associations by breast tumor subtypes. 

The study group included 32,826 women that participated in the Nurses’ Health study and donated blood samples in 1989-1990.  In 2000-2002, 18,743 of these women donated a second blood sample.  Women diagnosed with breast cancer between first and second blood collection, and those diagnosed with breast cancer within ten years of the second collection, were matched with control subjects.

After adjusting for several breast cancer risk factors, significant inverse associations were observed between a-carotene, b-carotene, lycopene, and total carotenoids and breast cancer risk with an overall 18–28% lower risk in the women with the highest blood levels compared to women with the lowest levels. The protective benefits of b-carotene and total carotenoids were more pronounced in leaner women (BMI < 30).  In addition, a-carotene, b-carotene, b-cryptoxanthin, and total carotenoids were associated with a 46% reduction in risk of the more aggressive types of cancer than recurred or caused death.

In this large prospective analysis with 20 y of follow up, women with the highest blood levels of carotenoids had a significant reduction in breast cancer risk, and particularly the more aggressive and lethal subtypes.

A Heather Eliassen et al.  Plasma carotenoids and risk of breast cancer over 20 y of follow-up. Am J Clin Nutr doi: 10.3945/ajcn.114.105080

Lutein and zeaxanthin supplementation improves measures of visual performance in healthy adults

At a Glance

A new study shows that supplementing with lutein and zeaxanthin—compounds contained naturally in green, leafy vegetables, such as kale and spinach—may improve measures of visual performance such as photostress recovery and the response to glare conditions. 

 Read more about this research below. 

Dietary carotenoids lutein and zeaxanthin are plant-derived pigments that concentrate in the inner layers of the macula region of the eye. The macular pigments act much like a sunscreen within the eye to protect the delicate tissues of the retina. It is well known that sufficient levels of these carotenoids reduce the risk of macular degeneration, a major cause of blindness in the elderly. Less is known of the benefits of supplementation of lutein and zeaxanthin in young, healthy adults. 

A new double-blind placebo controlled study published in Investigative Ophthalmology & Visual Science assessed the link between higher macular pigment optical density (MPOD) resulting from supplementation to improvements in glare disability, photostress recovery, and other measures of visual performance.   

The study included 115 young, healthy adults who either received a supplement containing a daily dosage of 10 mg of lutein and 2 mg zeaxanthin or a placebo over a one year supplementation period. Several measurements were collected at baseline and every 3 months: serum lutein and zeaxanthin, MPOD, photostress recovery, chromatic contrast and glare disability. MPOD is a measure of the amount of macular pigment present in the macular. Photostress recovery is a measure of how fast the eye recovers sight after being exposed to a flash of bright light. Chromatic contrast is the ability to discriminate an object from its colored surroundings. Glare disability is a measure of the amount of glaring light that can be tolerated before vision is significantly impaired. 

MPOD and serum lutein and zeaxanthin levels increased significantly in the treatment groups versus placebo. In the supplemented group, chromatic contrast and photostress recovery times improved significantly versus placebo during the study period. The researchers also found that improvement in glare disability was highly correlated to increased macular pigment density.  

The results of the current study demonstrate that lutein and zeaxanthin supplementation improves several measures of visual function in normal healthy individuals and adds to evidence from previous studies that increased MPOD results in improved visual performance. 

Hammond BR et al. A double-blind, placebo-controlled study on the effects of lutein and zeaxanthin on photostress recovery, glare disability, and chromatic contrast. Invest Ophthalmol Vis Sci. 2014 Dec 2;55(12):8583-9.