The study – published in the Journal of Investigative Dermatology – reports that supplementation with vitamin A in the form of retinol could offer protection against melanoma – a deadly form of skin cancer – in women. However, researchers also warned that too much vitamin A could also lead to serious side effects.
"We found a protective effect from supplemental vitamin A, more than you would get from a multivitamin," said lead researcher Dr. Maryam Asgari, of Kaiser Permanente Northern California, USA, however she warned that people should not take vitamin A in the hope it will reduce the risk of melanoma.
The authors also noted that while their study has uncovered an association between retinol supplementation and melanoma risk, it does not prove a cause-and-effect relationship.
"For us to really be able to recommend that [supplementation], we would need a trial," said Asgari. "Based on these findings I wouldn't recommend that the average person start taking vitamin A to prevent melanoma; more data needs to be obtained to make this recommendation."
The researchers noted that previous data from laboratory studies suggests the intake of vitamin A and carotenoids could have chemopreventive benefits against melanoma. However, they noted that epidemiological studies examining the association have so far yielded conflicting results.
Asgari and her team collected data from almost 70,000 people participating in a study on vitamins and lifestyle in the USA – the VITamins And Lifestyle (VITAL) cohort study. They reported that after five years of follow-up, 566 people had developed melanoma.
The research team revealed that they found no relationship between melanoma risk and vitamin A in the diet, with any beneficial effect seemingly limited to retinol – and not other forms of vitamin A carotenoids.
Retinol supplementation was found to be associated with 40% less cases of melonoma.
The protective effect of retinol was also found to be stronger among women, and in areas of the skin exposed to the sun, they said.
The authors concluded that retinol supplementation “may have a preventative role in melanoma among women.”
Source: Journal of Investigative Dermatology
Published online ahead of print, doi: 10.1038/jid.2012.21
“Association of Vitamin A and Carotenoid Intake with Melanoma Risk in a Large Prospective Cohort”
Authors: M.M. Asgari, T.M. Brasky, E. White