Medical Bag checked in with the following experts for further discussion regarding the implications of these various findings: Raja Sivamani, MD, MS, CAP, adjunct associate professor of clinical dermatology and director of clinical research at the University of California, Davis, and medical editor of; and Nina Shapiro, MD, director of pediatric otolaryngology and professor of head and neck surgery at the David Geffen School of Medicine at the University of California, Los Angeles, and author of the book, Hype: A Doctor’s Guide to Medical Myths, Exaggerated Claims and Bad Advice.

Medical Bag: Emerging research suggests that avoidance of sun exposure and supplementation with vitamin D may not be as beneficial as previously believed. What are your thoughts about these findings?

Dr Sivamani: We know that sunlight plays a role in a healthy lifestyle, but it does matter how it’s done. To broadly say that sunlight is good for people would discount the fact that it can also cause sunburns and deadly skin cancers. Sun avoidance and sun exposure need to be tailored to the patient. If my patient is very light skinned and burns within minutes, I will emphasize the need to be very careful with sunlight. On the other hand, if my patient has darker skin, I’m still going to discuss how sunlight can cause photoaging when done in excess, even if they don’t burn quickly.

I think prudent sun exposure has benefits beyond vitamin D, so supplementation will not make up for being outdoors, staying active, and the benefits on mood that are linked with careful sun exposure.8 The conversation about sun exposure needs to be individualized between the patient and their dermatologist.

Dr Shapiro: The notion of vitamin D supplementation in lieu of sun exposure stems from the notion that vitamin D, in its active form, is made by the skin’s exposure to sunlight. As sun exposure puts individuals at risk for skin cancers, the concept of instituting sun avoidance — which would reduce vitamin D levels — and replacement of sunlight with vitamin D supplementation has been in debate for several years.

In the VITAL study, there was no evidence that vitamin D supplementation reduced the risk for cancer and CVD. While these findings are important, there are likely many confounding factors that were not accounted for, such as diet, exercise, activity levels, family risks, and so on.

Medical Bag: Based on existing data, what are the relevant takeaways and treatment implications for clinicians?

Dr Sivamani: As noted above, clinicians should individualize the conversation to each patient, but guidelines should largely be aimed at reducing the public health epidemic of melanomas that can reduce lifespans by decades.

Dr Shapiro: The relevant takeaways are that vitamin D supplementation may not have any benefit on risk reduction for cancers and CVD. That said, the article discussing sun exposure as a potential factor for the reduction of cancer risk should be taken minimally, as sun exposure in and of itself carries known real risks. In that study, it’s possible that participants exposed to more sunlight were more physically active.

Medical Bag: What should be the focus of future efforts in these areas, in terms of research, guideline revision, or otherwise?

Dr Sivamani: A better conversation around smart sun exposure is needed: What are the right times to be outside? Is 10 to 15 minutes of sun exposure in the morning or evening adequate to get the benefits of sunlight? The next step is to have a more integrative conversation between dermatologists and other experts to understand each side of the debate and then develop guidelines that remain mindful of the deadly nature of skin cancer.

Dr Shapiro: Next steps should be to engage in longer-term studies looking specifically at serum levels of vitamin D, with and without supplementation, over long periods of time, and these serum levels’ association with positive or negative risks for cancer and CVD.


  1. Jacobsen R. Is Sunscreen the New Margarine? Outside. January 10, 2019. Accessed March 5, 2019.
  2. Manson JE, Cook NR, Lee IM, et al; VITAL Research Group. Vitamin D supplements and prevention of cancer and cardiovascular disease. N Engl J Med. 2019;380(1):33-44.  
  3. Moyer VA. Vitamin, mineral, and multivitamin supplements for the primary prevention of cardiovascular disease and cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2014;160(8):558-564.
  4. Institute of Medicine. Dietary Reference Intakes for Calcium and Vitamin D. November 30, 2010. Accessed March 5, 2019.
  5. Monaghan C, McIlvenna LC, Liddle L, et al. The effects of two different doses of ultraviolet-A light exposure on nitric oxide metabolites and cardiorespiratory outcomes. Eur J Appl Physiol. 2018;118(5):1043-1052.
  6. Lindqvist PG, Epstein E, Nielsen K, Landin-Olsson M, Ingvar C, Olsson H. Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort. J Intern Med. 2016;280(4):375-387.
  7. Lindqvist PG, Epstein E, Landin-Olsson M, et al. Avoidance of sun exposure is a risk factor for all-cause mortality: results from the Melanoma in Southern Sweden cohort. J Intern Med. 2014;276(1):77-86.
  8. Holick MF. Biological effects of sunlight, ultraviolet radiation, visible light, infrared radiation and vitamin D for health. Anticancer Res. 2016;36(3):1345-1356.

This article originally appeared on Medical Bag