Retinol supplements may cut melanoma risk

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By David Liu, PHD

Saturday Sept 29, 2012 (foodconsumer.org) -- A new study in the Journal of Investigative Dermatology suggests that taking retinol supplements, but not eating vitamin A rich foods may help reduce risk of melanoma, a highly deadly skin cancer.

The study led by Maryam M. Asgari of Kaiser Permanente Northern California in Oakland, California and colleagues conducted the study and found using individual retinol supplements was associated with 40 percent reduced risk of melanoma during a six year follow-up.

Laboratory studies showed that intake of vitamin A and carotenoids may chemoprevent melanoma and epidemiological studies were inconsistent, leading the researchers to examine whether dietary and supplemental vitamin A and carotenoids were linked to melanoma risk among 69,635 men and women in the VITamins And Lifestyle (VITAL) cohort study in western Washington. 

During an average of 5.84 years of follow-up, a total of 566 incident melanomas were recorded.  Those who took retinol supplements were found to have a 40 percent reduced risk of developing melanoma. And taking high doses of supplemental retinol (greater than 1,200 ug/day) was found associated with a 36 percent reduced risk, compared with those who did not take any retinol supplement.

The reduction in melanoma risk was particularly strong in sun-exposed anatomic sites. 

On the other hand, dietary or total intake of vitamin A or carotenoids was not associated with risk of melanoma. 

The researchers concluded "Retinol supplementation may have a preventative role in melanoma among women."

In the United States in 2008, 59,695 men and women were diagnosed with melanomas, and 8,623 people died from the skin cancer, according to the Centers for Disease Control and Prevention.

It is commonly believed that UV exposure is the major cause for melanoma. But unbelievers believe that UV is not the major cause for the deadly skin cancer because melanoma occurs more often than not on sites that are normally not exposed to UV rays or the sun.

One risk factor for melanoma, according to some vitamin D experts, is vitamin D deficiency. In the west, people often use sunscreens to block UV exposure, which increases risk of vitamin D deficiency, a condition that has been linked to 17 types of life-threatening cancers, according to epidemiologic studies.  Lab studies have shown that vitamin D can suppress melanoma cell growth.

UV rays are recognized as a cancer causing agent.  Over-exposure to UV rays can surely increase risk of skin cancer which in most cases does not pose any life-threatening risk.  But when a person tries to reduce the low-risk skin cancer risk by using sunscreens, he may end up having vitamin D deficiency if he does not take vitamin D supplements.  As a result, he is at increased risk for deadly melanoma.

In addition to taking retinol supplements as the current study suggests,  taking vitamin D supplements may be another way to prevent melanoma and many other serious types of cancers like breast cancer, as numerous studies have suggested.

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