What is Optimal Vitamin A Status?
Agasari and colleagues collected data from almost 70,000 men and women, 50 to 76y, participating in the VITAmins and Lifestyle (VITAL) study in Washington state. Over 5.8y, 566 people were identified with melanoma. Dietary and supplemental vitamin A and carotenoid intake was examined. After adjusting for melanoma risk factors, individual supplemental vitamin A use (retinol) was associated with a 40% reduced risk of melanoma. High-dose supplemental vitamin A (>1,200 ug per day) was associated with a 26% reduced melanoma risk vs non-users.
The primary author is quoted saying “Based on these findings I wouldn’t recommend that the average persons start taking vitamin A to prevent melanoma; more data needs to be obtained.”
In the PRIME study, low plasma levels of retinol was an independent predictor of coronary heart disease. After 5y of follow-up of 9,758 healthy men, 50-59y, living in France and Northern Ireland, 150 cases of incident coronary heart disease were identified. Plasma retinol levels <601 ug/L were associated with a 3-fold increased risk of coronary heart disease.
Brazionis and colleagues measured plasma retinol concentrations in 441 Australians and also found plasma retinol inversely associated with coronary heart disease risk. More relevantly to the study linking vitamin A with melanoma risk, is the observation that almost half of these community-dwelling adults had plasma retinol concentrations under 600 ug/L. Whereas none were deficient, these three studies raise the question: what is optimal plasma retinol status?
Asgari MM, Brasky TM, White E. Association of vitamin A and carotenoid intake with melanoma risk in a large prospective cohort. 2012 J Invest Dermatol Mar 1.
Gey KF, Ducimetiere P, Evans A, Amouyei P, Arveiler D, Ferrieres J, Luc G, Kee F, Bingham A, Yarnelli J, Cambien F. Low plasma retinol predicts coronary events in healthy middle-aged men: The PRIME Study. 2010 Atherosclerosis 208:270.
Brazionis L, Walker KZ, Itsiopoulos C, O’Dea K. Plasma retinol: A novel marker for cardiovascular disease mortality in Australian adults. 2011 Nutr Metab and CVD Nov.