Even more reason to eat your vegetables.
Researchers have determined that having a diet rich in vitamin A actually protects you from developing one of the commonest forms of skin cancer, squamous cell carcinoma.
According to their latest analysis of two large, ongoing, long-running population health studies (the Nurses Health Study and the Health Professionals Follow-up Study), both including over 25 years of follow-up data, it was found that those who consumed the least amount of vitamin A in their diet (the lowest quintile) were 17% more likely to develop cutaneous SCC than those who consumed the highest amount (the top quintile).
And even though this is all largely observational research, it’s pretty robust given the number of people involved (over 170,000 study participants over the two groups) and the detailed information collected (participants completed a comprehensive questionnaire on diet and lifestyle, including a checklist of over 130 food items biennially over the entire follow-up period).
And while the results reflect overall vitamin A intake, the researchers determined carotenoids (vegetable sources) made up the major proportion of the intake rather than retinoids (animal sources) or supplements.
The findings make sense physiologically as vitamin A has been shown to play a vital role in skin cell differentiation.
“Retinoids are essential for the maintenance of epithelial differentiation and decrease cellular proliferation, enhance normal differentiation of cells and reduce the formation of a tumour mass of undifferentiated cells”, the study authors said.
However previous analysis on the same cohorts on the same topic had delivered equivocal results. The researchers suggested that this was most likely because the follow up time had been much shorter (average 14 years among the women and 10 years among the men). In this latest study, researchers looked at the data after 28 years of follow-up in the Nurses Health Study and 26 years in the Health Professionals Follow-up Study.
The results also provide promise to patients known to be at high risk of SCC.
“Because synthetic retinoids used in chemoprevention of SCC in high risk population have adverse effects, dietary vitamin A could be explored as an alternative prevention strategy in the high risk and general population,” the researchers said.
Vegetables that contribute to a healthy vitamin A intake include carrots, sweet potato, spinach and broccoli.
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. JAMA Dermatol. 2019 Jul 31.
DOI: 10.1001/jamadermatol.2019.1937. [Epub ahead of print]