Sunshine vs Supplements

By Joel Fuhrman, M.D.

What Is The Safest And Best Way To Ensure That You Maintain Vitamin D Sufficiency?

Some people discourage (and even oppose) the taking of supplemental vitamin D and advocate getting more sunshine. They think that exposing your skin to sunshine is the only appropriate way to get the vitamin D you need and claim that “supplements are toxic.” For these “naturalists,” sun exposure is safe and supplements are not. This is not just bad advice; it is dangerous. People who follow it may die unnecessarily from cancer.

A fact that cannot be denied is that since most Americans work full-time in indoor jobs in northern climates, they are going to be vitamin D deficient unless they take supplements. Increasing vitamin D levels using supplements has been shown in multiple studies, including the Cochrane metaanalysis noted in the previous article, not only to be safe, but to extend life span and lower the risk of death from both multiple cancers and heart disease. To date, the interventional studies showing dramatic health benefits associated with increased blood levels of vitamin D have used supplementation (in reasonable dosages), not increased ultraviolet (UV) exposure. Vitamin D supplementation has a track record of more than 50 years of safety and benefit. Advocating against vitamin D supplementation because of distorted and unsubstantiated fears is even more reckless than advocating in favor of huge dosages of vitamin D.

Tragic Case

I routinely see people with medical difficulties and severe deficiencies who followed the “sunshine is best” advice. Not a month goes by that I do not see a raw-food vegan or natural hygienist in my office who has some troubling health condition that developed because of severe and longstanding vitamin D deficiency. Often a blood test shows that levels have fallen so low that no vitamin D is detectable (below 5 ng/mL), a situation that creates a host of medical problems and increases cancer risks. Unfortunately, the symptoms of vitamin D deficiency, such as fatigue and muscle complaints, do not develop until years after significant vitamin D deficiency has been present. Do not wait until severe deficiency develops, which it will in the vast majority of people who don’t take supplements, no matter how sunny it is where they live.

While we are on the subject of poor advice regarding appropriate supplementation, I frequently see vegans who have severe B12 deficiency. You would like to think that in the 21st century everyone would know that taking B12 supplements is vitally important for a healthful vegan diet. But when you ask people why they aren’t taking it, the answer is that some vegan “expert” gave them a false sense of security that they would get enough from seaweeds or some other “natural” foods. This misguided nonsense still is promoted on raw-food websites. Once, I had a famous raw foodist (author and radio personality) come to me semi-paralyzed and unable to walk unassisted, which I discovered was due to B12 deficiency. When he recovered most of his balance and could walk again after using B12 supplements, he announced on his radio show that he recovered from multiple sclerosis (MS) by using his raw-food diet.

I have seen many vegans and raw foodists in similar situations damaged by lack of supplements, some permanently so, I have reviewed the blood work of some who have died of these deficiencies. I am presently working with a patient (a longtime vegan natural food enthusiast) who lives in the northeast of the United States who has severe vitamin D deficiency (below 5 ng/mL) and additional test results and signs suggestive of cancer. With all of her reading and attending health conferences year after year, she never heard that vitamin D supplements were that important. She thought sun exposure on her face and hands was sufficient.

Skin Cancer And The Sun

UV radiation is a well documented human carcinogen, indisputably linked to the current ongoing increases in the rate of skin cancer. Because the UV action spectra for DNA damage leading to skin cancer and for vitamin D photosynthesis are identical, the harmful and beneficial effects of UV irradiation are inseparable. With the volume of studies in recent years showing the dramatic beneficial effects of vitamin D supplements (not from increased sun exposure), some have interpreted this new evidence as a reason to recommend removing all caution with regard to the sun and that everyone should utilize sunshine as the ticket to great health.

Obviously, exposure to sunshine and tanning beds place people at heightened risk of skin cancer; vitamin D supplements do not. There is no scientific evidence that vitamin D from the sun is better in some way or more effective at preventing bone disease, cancer, or heart disease than vitamin D supplements.

When you use sufficient sunshine exposure to guarantee optimal levels of vitamin D, you are placing yourself at unnecessary risk of skin cancer and wrinkling and aging your skin unnecessarily. And, regardless of this increased skin damage, sunshine is simply not available to our population of indoor workers living in northern latitudes to assure adequate protection against a variety of the most common cancers.

The one thing vitamin D supplements cannot do that natural sunshine and bright light can is elevate mood and aid in the treatment of depression. Light coming in to the eyes (not on the skin) aids in the production and timing of the melatoninserotonin axis, potentially aiding people prone to insomnia and depression. The bright light halts melatonin production during daylight hours, enabling people to make more of it at night when it is needed. It also encourages the secretion of serotonin during the day. Some people living in northern climates may benefit from a therapeutic light used in the morning, especially during the winter months when sunshine is in short supply.

Avoiding All Cancers

Non-melanoma skin cancer linked to cumulative sun exposures is the most common malignancy in the U.S. Furthermore, the incidence of malignant melanoma that has been associated with intermittent high-intensity sun exposure has risen dramatically; it now affects one in 87 Americans.10

To prevent melanoma and non-melanoma skin cancer, many physicians and physician organizations urge sun avoidance when UVB radiation is most intense and suggest a combination of protective clothing and the use of sunscreens. However, the midday sun, when the damaging rays are most intense, is when vitamin D production is strongest. With the new findings to assure vitamin D production for general health above 35 mg/ml, more midday sunshine on larger areas of exposed skin will be necessary for adequate vitamin D production, increasing skin cancer risk. Worse, there still is no guarantee that your vitamin D levels will be adequate.

Inadequate sun exposure is often blamed for the high prevalence of low vitamin D status, but even generous exposure to the sun cannot ensure sufficiency. Research conducted by the Osteoporosis Clinical Research Program found that for many people, vitamin D levels can remain low despite abundant exposure to sunlight. They studied young Caucasian adults living in Hawaii who averaged 29 hours per week of sun exposure and found 51 percent of this population had vitamin D levels lower than 30 mg/ml.11 There is a wide variability in people’s ability to convert sun exposure into vitamin D. People with darker skin have even less ability to make sufficient vitamin D from sun exposure. This study also was of interest because it found that the most vitamin D obtainable by virtually all-day exposure to the sun was 62 ng/mL, illustrating that those who advocate that we maintain levels of 50–100 ng/mL are promoting unnaturally high levels. Since 62 ng/mL is the highest “natural” dose of vitamin D you could obtain in a day, it seems prudent to use that value as an upper limit (and not 80 ng/mL) when prescribing vitamin D supplementation.

Overall lifetime UVB exposure is the strongest causation factor in the etiology of squamous cell carcinoma and actinic keratosis, while intermittent UV exposure and sunburning appear to be more important causation factors in the etiology of melanoma and basal cell carcinoma. It is tragic that in the search for “natural” vitamin D some people will get so much sun exposure that they will need disfiguring facial surgeries, when vitamin D supplements could have met their needs easily and safely. Some sunshine enthusiasts (illogically) argue that many more people die of colon, breast, and prostate cancer that can be prevented by sun exposure, so we should not worry about the 10,000 deaths in the U.S. each year from sunshine-caused skin cancer. Of course, this is an irrelevant argument when we can protect against all of these cancers by combining vitamin D supplements with more judicious and careful sun exposure habits.

Our modern atmosphere, after significant ozone depletion, no longer supplies safe levels of sunshine. We have changed the nature of sunshine with ozone-depleting pollution, and the result is more exposure to the damaging rays of the sun. The demonstrated link between dramatically higher occurrence of skin cancer and excessive exposure to UV radiation in Australia and New Zealand indicates the need for higher intakes of supplemental vitamin D even where the climates are hot and sunny all year, making it theoretically possible to derive adequate vitamin D from sunshine alone. The notion that we should rely on sunshine for our vitamin D needs is impractical, impossible for most people to achieve, and unsafe.

How Much Sun Is Safe?

If you do decide to tan with either the sun or a tanning lamp, be careful not to burn, and build up the melanin in your skin very gradually. The gradual and slow buildup of a tan to prevent any redness or burning is important to decrease the chance of developing melanoma. However, even gradual tanning increases wrinkling, aging of the skin, and squamous cell carcinoma. Consider how smooth and wrinkle-free your buttocks and other non-sun exposed areas of the body are. But whether you get sunshine or not, taking steps to ensure that you maintain adequate blood levels of vitamin D also will offer some protection against melanoma and skin cancer.12

Whether it is from a supplement, the sun, or a combination of the two, having an adequate level of vitamin D is important for reducing the risk of all cancers, including cancers of the skin. Of course, a healthy high nutrient “nutritarian” diet can significantly reduce one’s risk of all cancers, too, and that includes skin cancer. Green vegetables offer the most protection against skin cancer, whereas diets rich in animal fats pose the highest risk.13 But, when you combine a high-green diet with adequate vitamin D blood levels, you are truly practicing an anticancer lifestyle. Imagine all of the lives that could be saved if everyone just ate more greens and made sure their vitamin D levels were adequate.

I advise limited sun exposure, asking people to use a non-chemical, non-nano-technology sunscreen or hat to cover their face and back of their neck and back of hands and wrists, areas that get heightened, repeated, and direct exposure when outdoors. Using a safe and nonchemical sunscreen to protect the nose, cheekbones, and areas around the eyes will keep you looking younger and prevent wrinkling (especially around the eyes) as you age. It also will prevent the areas that get most of your cumulative sun exposure from developing actinic keratosis and squamous cell carcinomas.

For most of us who work indoors and live in the northern half of the U.S., it would be impossible to go outside in shorts or a bathing suit two to three times a week during most of the year. If you can, and you live in a sunny warm climate, it is safe to get 10–20 minutes of sun exposure on your arms, legs, and trunk a few times a week, but wear sunscreen protection for your face and area described above. If you are in a hot and sunny climate and plan on being outside longer than 20 minutes, or if you are on vacation in a sunny climate or it is the summer and you have to be outdoors exposing yourself to stronger and more prolonged sun, then the use of sunscreen on your full sun-exposed skin would be appropriate to reduce the potential for sun damage.

Remember that people with fair complexions and lifestyles that could be associated with the possibility of getting repetitive sunburns have no safe limit, and they should be very careful to avoid even 20 minutes of unprotected midday sun, as it could cause some burning and damage. The amount of safe sunshine is extremely variable from person to person, so erring on the side of caution is always advisable.

Sunscreens and Skin Cancer

Sunscreen use has been shown to reduce the risk of squamous cell carcinoma and actinic keratosis, both linked to UVB, but because most chemical sunscreens do not adequately block UVA they do not protect against melanoma. Mechanical or mineral sunscreen ingredients (such as zinc oxide and titanium dioxide), not chemical sunscreens, protect from both UVA and UVB, and they are also much safer because no chemicals are absorbed into the body or bloodstream. The only disadvantage to the thicker, all mineral- ingredient sunscreens is that they could leave a thin, translucent, white film on your skin.

Enjoy the sun, but please be smart about it!


1. Lim HW, Cooper K. The health impact of solar radiation and prevention strategies: report of the environment council. J Am Acad Dermatol 1999; 41:81-99.

2. Binkley N, Novotny R, Kruger D, et al. Low vitamin D status despite abundant sun exposure. J Clin Endcrinol Metab 2007;92(6):2130-2135.

3. Evans SRT, Houghton AM, Schumaker L, et al. Vitamin D receptor and growth inhibition by 1,25- dihydroxyvitamin D3 in human malignant melanoma cell lines. J Surg Res 1996;61:127-133.

4. Ibiebele TI, van der Pols JC, Hughes MC, et al. Dietary pattern in association with squamous cell carcinoma of the skin: a prospective study. Am J Clin Nutr 2007;85(5):1401-8.

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