Ever wonder why it just feels good to soak up some sunshine? Warmth aside, sunlight offers your body many health benefits. As with Goldilocks, you need to get the just right amount of it, though, as too much sun is associated with premature aging and increased risk of skin-cancer.
How to Get Vitamin D
Your body synthesizes vitamin D3 from the ultraviolet (UV) rays you absorb through your skin. Known as “the sunshine vitamin” (even though it is technically a hormone-like substance), vitamin D helps keep your immune system functioning properly and helps protect you against some cancers, cardiovascular disease and autoimmune disorders.
Very few foods are natural sources of vitamin D, so people who live at very northern or southern latitudes – where sunlight is not as plentiful and strong − tend to be vitamin D deficient due to lack of sun exposure. For these populations, taking a vitamin D supplement and/or eating fortified foods can prevent deficiency.
More Reasons Sunshine Is Good for You: Improved Blood Pressure and Better Heart Health
Since the early 1940s, when it was suggested that sun exposure could promote immunity against cancer, researchers have demonstrated that higher-latitude living is associated with greater incidence of colon, breast and prostate cancers, which may in part be due to vitamin D deficiency. Studies have shown that these populations are also more prone to autoimmune disease and high blood pressure, both of which increase risk of heart disease.
The connection between sun exposure and lower blood pressure was brought into focus in 2014 in a fascinating study conducted by researchers in the U.K. and reported in the Journal of Investigative Dermatology. According to the study, sunlight has a dilating effect on arteries and actually lowers blood pressure, an effect, the researchers said, that may trump the risk of skin cancer. The reported mechanism was not related to vitamin D but to nitric oxide, a chemical made in arterial tissue that keeps blood vessels flexible and dilated.
The researchers plan more studies to examine risks of hypertension, heart disease and skin cancer in people who receive different amounts of sun exposure. Their findings could influence current recommendations on exposure limitations due to fear of skin cancer. There are comparatively low numbers of deaths from skin cancer compared to cardiovascular disease. Moreover, population studies show that sunlight exposure is a factor in reducing cardiovascular, as well as all-cause, mortality.
How Much Sun Do You Need?
Clearly, sunlight is beneficial for many reasons, but how much sun do you need? Ideally, to satisfy your vitamin D needs, you want to soak up the sun’s mid-day rays (between peak hours of 10 a.m. and 3 p.m.) for 10 to 20 minutes each day. It’s important that you don’t wear sunscreen during this time because sunscreen inhibits vitamin D3 synthesis by blocking UV rays. But if you are out in the sun regularly and for longer periods of time, especially during peak hours, you may put yourself at risk of UV damage if you don’t use protective clothing or sunscreen.
And don’t worry about getting too much Vitamin D: no amount of sunlight causes vitamin D toxicity. Your body converts excess vitamin D3 from the sun into inert substances, making sunlight Nature’s perfect design for vitamin D3 synthesis. What happens in your body is that sunlight converts a form of cholesterol in your skin into a compound that is further processed into vitamin D. Today, vitamin D toxicity only really happens if you supplement too much, over 10,000 units a day, an amount that is far beyond the usual and safe recommendations.
Does Everyone Need the Same Amount of Sunlight?
People around the globe have various requirements for sun absorption. Other factors affecting cutaneous production of vitamin D include age, melanin pigmentation, latitude, seasonal changes, and time of day.
People over the age of 70, for example, make about one-quarter the amount of vitamin D as 20-year-olds exposed to the same amount of sunlight. That’s because production of 7-dehydrocholesterol (the substance in the skin that converts sunlight rays to a pre-vitamin D form) declines with age. Thus, moving to a warmer, sunnier climate later in one’s life is not a bad health preservation strategy. But, of course, always be careful about how much sun you get.
People with darker skin color also need to absorb more sun to make vitamin D than lighter- skinned people. That’s because they have more melanin pigmentation in their skin that dissipates much of the absorbed UV radiation as heat and thus provides protection against skin damage. Melanin is the primary factor related to skin color.
Additionally, time of day, season, and latitude all affect the angle at which the sun’s rays enter the ozone layer (which also absorbs them). In the U.S., Canada, and other areas of higher latitude, it’s especially difficult for people of African descent to absorb enough sunlight to make sufficient vitamin D during the winter months.
How to Find Out if You’re Vitamin D-Deficient
If you’re worried that you’re not getting enough vitamin D, ask your doctor to test your blood levels to see if you are deficient. Michael Holick, M.D, a leading medical expert on Vitamin D, recommends that blood levels be between 40 and 60 ng/mL (nanograms per milliliter serum 25-hydroxyvitamin D). Blood levels below 20 ng/mL indicate deficiency. More on this in my interview article with Dr. Holick and in Vitamin D3 and Your Health at Drsinatra.com.
If you live in Michigan, Alaska, Toronto or other northern latitude location and are wondering how to get vitamin D, here are some sunshine alternatives to get you through the dark cold days of winter:
- Take a mid-winter vacation to a warmer sunnier climate.
- Eat foods with Vitamin D. Fatty fish like salmon, mackerel and sardines, as well as fish liver oils, are among the few natural dietary sources of vitamin D3. Lesser amounts of vitamin D may be found in egg yolks, cheese and beef liver. Also, as most milk sold in the U.S. has been artificially fortified with vitamin D, it can be a good dietary source as long as the milk is organic (less toxic).
- Supplement with Vitamin D. Look for Vitamin D-3 (the form the body manufactures from sunlight); I generally recommend taking 2,000 units per day. More may be necessary for individuals with compromised health in order to reach a desirable blood level.
- Use “happy lights” / full spectrum lights – these products provide a full spectrum of light, or range of electromagnetic wavelengths equivalent to natural sunlight.
References and Resources:
- Calvo MS, Whiting SJ, and Barton CN. Vitamin D fortification in the United States and Canada: current status and data needs. Am J Clin Nutr. 2004;80(6): 1710S-1716S.
- Heaney RP. Vitamin D: criteria for safety and efficacy. Nutr Rev. 2008 Oct;66(10 Suppl 2):S178-81.
- Holick, MF. Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancer and cardiovascular disease. Am J Clin Nutr. 2004;80(6):1678S-1688S.
- Liu D, et al. UVA irradiation of human skin vasodilates arterial vasculature and lowers blood pressure independently of nitric oxide synthase. J Invest Derm. 2014;134(7):1839–1846.
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