Sunlight, Vitamin D3 and Your Health

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Sunlight, Vitamin D3 and Your Health

Vitamin D3 is both a vitamin and a hormone. It acts as a vitamin when it binds with calcium for proper absorption, humans cannot digest calcium without adequate amounts of Vitamin D3. Sufficient Vitamin D3, along with diet and exercise, has emerged in the last few years as one of the most important preventive factors in human health.

Vitamin D3 deficiency can result in Obesity, Type 2 Diabetes, High Blood Pressure, Depression, Psoriasis, Fibromyalgia, Chronic Fatigue Syndrome, Kidney Stones, Osteoporosis, & Neuro-degenerative diseases including Alzheimer’s disease. Eventually, Vitamin D deficiency may even lead to Cancer (especially breast, prostate, and colon cancers). Vitamin D3 is believed to play a role in controlling the immune system (possibly reducing one’s risk of cancer and autoimmune diseases), increasing neuro-muscular function and decreasing falls, improving mood, protecting the brain against toxic chemicals, and potentially reducing pain. Hundreds of studies now link vitamin D deficiency with significantly higher rates of many forms of cancer‚ as well as heart disease‚ osteoporosis‚ multiple sclerosis and many other conditions and diseases.

We spend less time in the sun today than at any point in human history, it is estimated that more than 1 billion people worldwide that are vitamin D deficient. Fifteen to twenty minutes of sunshine each day, in the nude, helps your body manufacture about 10,000 to 15,000 IU’s (International Units) of vitamin D3 per day. The problem is that for most people full exposure to the sun is just not possible on a daily basis, and they have been told to avoid the sun and use sunscreens due to fears of skin cancer. Clearly, there needs to be a greater awareness of the benefits of sunlight, its role in producing Vitamin D3, and the importance of naturally produced D3 for our overall health and reduction of disease.

One way to help increase your vitamin D levels is to eat foods high in natural Vitamin D3, including Cod liver oil, salmon, mackerel, & sardines, egg yolks (from free range chickens), and beef liver (from grass-fed cattle).

Many foods have now been “fortified” or supplemented with Vitamin D, but this has not resulted in an overall increase in Vitamin D levels. This is likely because many food and supplement manufacturers rely on an inexpensive form of synthetic Vitamin D called “ergocalciferol”- a form of Vitamin D2. Some brands of organic whole milk are fortified with vitamin D; just make sure that the brand you buy contains D3 and not the synthetic Vitamin D2. Make sure that the brand of milk that you buy it is not fortified with Vitamin A, since Vitamin A offsets many of Vitamin D’s benefits.

There is much debate among government advisers on an RDA for vitamin D. Currently, the US Recommended Dietary Allowance (RDA) for vitamin D is 600 IU, which is the minimum amount needed to protect against rickets and osteomalacia, and the upper limit for Vitamin D supplementation is now 4000 IU.  If you take Vitamin D supplements make sure it is Vitamin D3 and not D2, and take Vitamin D3 supplements with food. Many specialists recommend a Vitamin D3 intake of 2000-5000 IU/ day depending on lab levels. While vitamin D3 supplements are an alternative means of producing vitamin D when regular, non-burning sun exposure is not possible, oral supplementation of vitamin D is not nature’s intended means of producing this vitamin.

Several studies observing large groups of people found that those with higher vitamin D levels also had lower rates of cancer. How vitamin D may do this is still under study, but there are lots of reasons to think it can:

  • Lab and animal studies show that vitamin D stifles abnormal cell growth, helps cells die when they are supposed to, and curbs formation of blood vessels that feed tumors.
  • Cancer is more common in the elderly, and the skin makes less vitamin D as people age.
  • Darker-skinned individuals have higher rates of cancer than those that are lighter-skinned, which prevents them from making as much vitamin D.
  • Vitamin D gets trapped in fat, so people who are obese tend to have lower blood levels of Vitamin D. They also have higher rates of cancer.
  • Diabetics, too, are prone to cancer, and their damaged kidneys have trouble converting vitamin D into a form the body can use.
  • People in the northeastern United States and northerly regions of the globe like Scandinavia have higher cancer rates than those who get more sunshine year-round.
  • During short winter days, the sun’s rays come in at too oblique an angle to spur the skin to make vitamin D.

The best Vitamin D comes from the sun.

Sunlight has both UVA and UVB rays; our skin absorbs both but in different ways. Both types of rays can contribute to health risks with overexposure; however UVB rays are solely responsible for the health benefits of sunshine. Tanning beds, unfortunately, cannot make up the difference in our lack of UVB rays from sunlight that the body needs to make Vitamin D3. Most commercial tanning beds are calibrated to emit 95% UVA rays that give us that golden brown tan, but not the ability to produce Vitamin D3.

Regular, non-burning sun exposure allows humans make 90 percent of our vitamin D naturally from sunlight exposure to our skin – specifically, from UVB exposure to the skin, which naturally initiates the conversion of cholesterol in the skin to vitamin D3. Sun exposure to the skin makes thousands of units of vitamin D naturally in a relatively short period of time. Unlike dietary or supplementary vitamin D, when you get your ‘D’ from sunshine your body takes what it needs, and de-metabolizes any extra. Because too much ‘D’ from dietary supplements may cause the body to over-process calcium, nobody really knows for sure how much is too much when supplementing vitamin D. On the other hand, sunlight-induced vitamin D doesn’t have that problem – it’s the way your body is intended to make it.

Nutrition experts think vitamin D-3 supplements may be especially helpful if your lifestyle does not allow for sun exposure, during winter and for dark-skinned people all the time. Here is a comparison showing the amount of Vitamin D that you can receive from the sun, food sources, and supplementation:

Sunlight Exposure (full body exposure) Sun exposure to the arms and legs for 10-15 minutes. The amount of vitamin D produced depends on the intensity of the UVB in the sun and many other factors. Darker-skinned individuals may need 5-10 times more exposure than a fair-skinned person to make the same amount of vitamin D. In northern climates sunlight is too weak in parts of the year to make any vitamin D – a period referred to as ‘Vitamin D Winter’. 3,000 – 20,000 IU
Salmon (3.5 oz. of fresh, wild salmon) 600 – 1,000 IU
Salmon (3.5 oz. of fresh, farmed salmon) 100 – 250 IU
  Fortified Whole Milk, 8-oz. glass (Vitamin D is supplemented into milk. It doesn’t occur naturally in milk)   100 IU
Fortified Multi-vitamin           400 IU [1]

So what about sunscreens? Are they really helping us prevent skin cancer?

Given all the upsides of basking at least briefly in the summer sun, many experts now worry that public-health messages warning about skin cancer have gone overboard in getting people to cover up and seek the shade. Robyn Lucas, an epidemiologist at Australian National University who led a study published in the February issue of the International Journal of Epidemiology. Her finding: Far more lives are lost to diseases caused by a lack of sunlight than to those caused by too much. According to Lucas, “Sun protection messages arose in response to rapidly increasing rates of skin cancers, and they were an essential public-health message. But we now recognize that some sun exposure is important for health, at the very least, to maintain healthful vitamin D levels, and sunscreen blocks out nearly all UV radiation”.

Taking this into account, the Cancer Council of Australia has eased its sun protection message a little over the last few years and now recommends that if you’re out in the sun for relatively short periods, with a UV index less than 3, which indicates a moderate amount of UV rays hitting your area on a given day, then sunscreen and other sun protection (like hats and protective clothing) are not required. According to this information, I  believe that we all need a little unprotected time in the sun during the middle hours of the day (when the sun is at its highest and UV-B rays can penetrate the atmosphere).

While overexposure to sunlight carries risks, the cosmetic skin care industry has misled the public into believing that any UV exposure is harmful. Although no research has shown that regular, non-burning exposure to UV light poses a significant risk of skin damage, it is undeniable that sunscreen use has profoundly increased in the past few decades. Yet in spite of that increase, the incidence of melanoma (CMM) continues to climb in the US. A clinical review in the Journal or the American Board of Family Practice,[2] comes to the following conclusions:

1. “Despite the availability and promotion of sunscreen for decades, the incidence of CMM continues to increase in the U.S. at a rate of 3% per year.”

2. There currently is little evidence that sunscreens are protective against CMM.

3. A number of studies suggest that the use of sunscreen does not significantly decrease the risk CMM, and may actually increase the risk of both CMM and sunburns.

The author of the report, Dr. Margaret Planta, also notes that the environmental protection Agency (EPA), states that “there is no evidence that sunscreens protect you from malignant melanoma.”[3] The Melanoma International Foundation has (MIF) has stated, “Melanoma is epidemic: rising faster than any other cancer and currently it affects 1 in 75. In 1935, only one in 1500 was struck by the disease.” In other words, as sun exposure has dramatically decreased, melanoma has exponentially increased.[4] Quite obviously, the use of sunscreens has been one reason for the decrease in sunlight exposure. Consider this: if UVR exposure is the cause of CMM as stated by the IMF, there should be a simultaneous decrease in melanoma as sunscreen use has increased. However, according to Kline & Company, a research group, sales of sunscreens in 1972 were $33 million; in 2008, sales were $650 million.[5]

So how much sun is it safe to get without sunscreen?

It’s difficult to quantify how much since skin pigmentation affects how much radiation your skin absorbs: The darker the skin, the more it’s protected against skin cancer but the less able it is to absorb UV-B rays. It also depends on how much skin is exposed and the time of day. If you’re fair skinned and sunning yourself outside in a bathing suit at noon, you only need a few minutes without sunscreen. If you’re already tan or of Hispanic origin, you need maybe 15 to 20 minutes. Black skin may require six times the sun exposure to make the same vitamin D levels as a very fair-skinned person.


[1]Holick, MF. Vitamin D Deficiency. New England Journal of Medicine, July 2007

[2] Margaret B. Planta, MD Sunscreen and Melanoma: Is Our Prevention Message Correct? J Am Board Fam Med 2011;24:735–739.

[3] United States Environmental Protection Agency. Sunscreen: The Burning Facts. Available at:

[4] Melanoma International Foundation, 2007 Facts about melanoma. Sources: : National Cancer Institute 2007 SEER Database, American Cancer Society’s 2007 Facts and Figures, The Skin Cancer Foundation, The American Academy of Dermatology.

[5] Kline & Company’s Cosmetics & Toiletries USA Annual Service (1972 and 2008 editions).