Increasing consumption of dietary vitamin A may reduce the risk for incident cutaneous squamous cell carcinoma (SCC), a study in JAMA Dermatology suggests.
Cohort data from the Nurses’ Health Study between the years 1984 and 2012 as well as the Health Professionals Follow-up Study between 1986 and 2012 were prospectively examined. The study analyzed participants’ diets, with a specific focus on dietary intake of vitamin A, retinol, and carotenoids, as well as rates of incident SCC during these time periods. Diet was assessed with a validated food frequency questionnaire consisting of approximately 130 food items. Consumption frequency of each food item was multiplied by its nutrient content to assess nutrient intakes.
Among 75,170 women in the Nurses’ Health Study (mean [SD] age, 50.4 [7.2] years) and 48,400 men in the Health Professionals Follow-up Study (mean [SD] age, 54.3 [9.9] years), a total of 3978 cases of SCC were identified.
For women, the median total vitamin A consumption was 6808 IU/d in the first quintile and 21,691 IU/d in the fifth quintile vs 7236 IU/d in the first quintile and 26,539 IU/d in the fifth quintile for men.
Higher total consumption of vitamin A was associated with a reduced risk for SCC in the pooled cohort. Using quintile as a reference, decreasing hazard ratios (HRs) were observed for the increasing quintiles of vitamin A intake (quintile 2: HR, 0.97; 95% CI, 0.87-1.07; quintile 3: HR, 0.97; 95% CI, 0.80-1.17; quintile 4: HR, 0.93; 95% CI, 0.84-1.03; quintile 5: HR, 0.83; 95% CI, 0.75-0.93; P <.001 for trend).
Individuals with a higher intake of retinol and certain plant-derived carotenoids also had reduced risk for SCC. Specifically, this association was observed with the highest quintiles of vitamin A intake compared with the lowest quintiles for total retinol (pooled HR, 0.88; 95% CI, 0.79-0.97; P =.001 for trend), beta cryptoxanthin (pooled HR, 0.86; 95% CI, 0.76-0.96; P =.001 for trend), lycopene (pooled HR, 0.87; 95% CI, 0.78-0.96; P <.001 for trend), and lutein and zeaxanthin (pooled HR, 0.89; 95% CI, 0.81-0.99; P =.02 for trend).
The fairly homogenous nature of the population as well as the use of food frequency questionnaires represent potential limitations of the study.
Despite the potentially beneficial effects of vitamin A on reducing risk for SCC, the researchers conclude that the “risks and benefits of high vitamin A intake should be considered individually,” considering the association between high doses of vitamin A and an increased risk for osteoporosis and hip fractures.
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Kim J, Park MK, Li WQ, Qureshi AA, Cho E. Association of vitamin A intake with cutaneous squamous cell carcinoma risk in the United States [published online July 31, 2019]. JAMA Dermatol. doi:10.1001/jamadermatol.2019.1937