Sunshine and Vitamin D: A Dermatologist’s Dilemma

by Samantha on Saturday

What do mad dogs, Englishmen, and spring breakers have in common? If you guessed, “They go out in the midday sun,” you are correct! In Europe, the English, as well as the rest of their northern European counterparts, all flock to Italy, Greece, Spain, and other tropical locales for their vacations, where they can’t wait to get their pasty white selves into the sun. I wince when I think of the sunburns!

As for the spring breakers, we’re all very familiar with the annual invasion of our southern coasts by thousands of students from all over the country. After having been cooped up in libraries and dorm rooms all winter, they descend on the beach in droves, for a week of beer, volleyball and sun, sun, sun! We dermatologists joke about “future patients” and “job security.” Aren’t we clever! But now it’s time for a little confession on my part. I have a small guilty pleasure. I have to admit that sometimes, like around this time of year, when the temperatures are pleasant, I enjoy the feeling of sun on my skin. It feels good! There, I’ve said it. Of course, I can’t enjoy this pleasure for long, as my dermatologist guilt quickly sets in and I force myself to go inside or seek shade.

But let’s look at why people are drawn to the sun. Studies have shown that ultraviolet exposure, whether it’s from the sun or from indoor tanning beds, stimulates the production of endorphins, our natural “feel good” hormone. There have even been studies showing that tanning is addictive in some people. So, why, if the sun is so bad for us, does it feel so good?

Well, maybe because it is good for you. What? Did I just say that? Yes, the sun is good for you because of the sunshine vitamin, vitamin D. Vitamin D is actually a hormone, and the active form of the hormone is synthesized in the skin from its precursor. Ultraviolet radiation from the sun catalyzes this reaction. Without sun, we cannot make vitamin D. There are no natural dietary sources, except for wild salmon and other oily fish. (Thus the reason for giving cod liver oil to children in the old days.) Milk and orange juice contain vitamin D, but only because they’ve been fortified.

Vitamin D has been the subject of a lot of press lately, at least in medical circles. Most people know that it is important for bone and calcium homeostasis, but recent research has shown that vitamin D also plays an important role in maintaining our immune systems (fighting off infections), preventing high blood pressure and coronary disease, preventing many internal cancers and regulating blood sugar and insulin levels. This is very exciting stuff! But not too surprising when you realize that over 1000 of our genes contain vitamin D response elements, meaning that vitamin D is required for the genes to work. Thus, vitamin D is an integral nutrient that our bodies need to function correctly. And we can’t get enough of it through our diet alone. Sadly, we are experiencing an epidemic of vitamin D deficiency in much of the world.

We have now arrived at one of the most important dilemmas in dermatology today. This is what makes us dermatologists squirm. We’ve spent our whole careers educating our patients to avoid the sun and wear sunscreens. We’ve inadvertently contributed to the Vitamin D crisis. What to do? I can’t speak for all my colleagues, but I still can’t easily bring myself to tell patients to go out in the sun. As a cosmetic dermatologist, I see the evidence of photoaging every day (wrinkles, dark spots, rough texture, sallowness.) As a general dermatologist, I diagnose and treat skin cancer every day. Skin cancer is undeniably correlated with long term sun exposure.

In any event, what is the right amount of sun exposure to get enough Vitamin D? You’d think the answer would be simple, but it is not. Data are conflicting and confusing. The dermatologic literature indicates that anywhere from 2 to 30 minutes of unprotected exposure of limited areas (such as arms and legs) per week is enough, while the endocrine literature indicates much longer exposures, and larger surface areas are needed. Other variables that impact vitamin D synthesis include latitude, season, air pollution, skin type, and obesity. It’s pretty complex.

The good news is that we do have supplements. The bad news is that no one can agree on how much vitamin D to take. After researching this article, here is what I can tell you:

1. Everyone should take a vitamin D supplement; I recommend 1000-2000 units per day of vitamin D3 (the active form) daily for adults. You may need more if you are elderly, or dark skinned, or ill. If you can’t find D3 at your drugstore or grocery store, try or

2. Although the recommended daily intake was recently raised from 400 to 600 IU per day, many vitamin D experts still regard this as too low.

3. Vitamin D toxicity is theoretically possible, but very rare, despite what you may have heard. There has never been a reported case of vitamin D toxicity from natural sunlight exposure, which can generate 10,000 units or more daily.

4. Adequate D levels are defined as greater than 30 mg/ml. Optimal levels (similar to a lifeguard or to our equatorial ancestors) would be in the 50-80 ng/ml range. Aim for this level. At this level, your body can start to store D for future use.

5. If you are in doubt, have your level checked. It’s an easy blood test.

6. Stop feeling guilty about limited amounts of sun exposure. Life is too short! Enjoy a few of those endorphins!

Comments on this entry are closed.

Previous post:

Next post: