Nothing makes headlines like controversy. Somewhere between the fields of nutrition and dermatology a media darling is brewing, and it will be hitting the airwaves faster than you can spell “sunscreen.” What is it that could raise the ire of a whole medical specialty and cause the resignation of a faculty member from the department of dermatology at a prestigious school of medicine? The notion that a tiny bit of unprotected sunshine may actually improve your health.
The Sunshine Vitamin
Vitamin D is known as the sunshine vitamin because most of the vitamin D that your body requires can come from exposure to sunlight. Ultraviolet energy from the sun is absorbed by the skin and converted into vitamin D. Vitamin D is also available from a handful of foods that we eat. It is found naturally in oily fish like salmon and mackerel and fish oils, and in vitamin D-fortified milk and cereals.
Because vitamin D is limited to only this small number of foods, we greatly depend on sunlight to cover our needs. Although previous generations received enough exposure to the sun to manufacture adequate supplies of vitamin D, new research has uncovered that a lot of people today, particularly those who live in northerly climates, are not getting enough sunlight to meet their needs for vitamin D. Some experts are referring to it as an epidemic of vitamin D deficiency.
A Dynamic Duo
Vitamin D is a nutrient, but it is also classified as a hormone. The maintenance of calcium balance and bone health is controlled by an elegant cascade of biochemical events that links vitamin D and calcium like two dancers performing a pas de deux. Each time calcium levels fall, vitamin D is there to help it regain the balance. Vitamin D promotes the absorption of calcium from the intestines and the resorption of calcium in bones. It acts on the kidneys and intestines to maintain adequate levels of calcium and phosphorus for bone formation, and it is integrally involved in the maintenance of calcium levels in blood.
Without enough vitamin D children develop the deficiency disease, rickets. Adults deficient in vitamin D suffer from soft bones that can precipitate osteoporosis.
Because vitamin D is intertwined with calcium balance, it plays a crucial role in muscle, cardiac, and neurological functions. It may also be linked to effects on cell growth, immune function and decreasing risks of developing cancers of the prostate, breast and colon. The recent discovery of calcium’s role in genetic control of fat metabolism places vitamin D in a pivotal position to assist calcium with energy balance and body weight maintenance. And when it comes to mood, vitamin D is required for the manufacture of serotonin, the feel-good neurotransmitter in your brain.
The Sunshine Curse
It is well known that sun exposure can lead to sun damage. The ultraviolet A and B rays of the sun penetrate below the protective layers of the skin to cause degeneration of the supporting collagen, genetic damage to the cells, and weakened function of immune cells within the skin. It is estimated that the majority of skin aging and facial damage attributed to aging is actually the result of chronic photo aging caused by exposure to the ultraviolet (UV) rays of the sun. Years of sun damage can lead to skin cancer. Protection from sun exposure may be the single most important health issue related to skin care. These risks hold true for both direct exposure to sunlight as well as routine use of tanning beds.
The process of tanning is actually a form of damage control. Having a tan actually demonstrates that the skin has had to protect itself from an onslaught of UV rays and the tan is the first victim to that onslaught. Melanin is a natural sunscreen that evolved to protect humans from radiation in the equatorial regions of the world. Darker-skinned individuals with greater proportions of melanin in their epidermis are more protected from the damaging rays of the sun compared to light-skinned individuals, but they are less efficient at producing vitamin D.
Is Any Sun Safe?
Here lies the controversy. According to Dr. Michael Holick, a leading vitamin D researcher, director of the Bone Health Care Clinic at Boston University Medical Center and former faculty member of the department of dermatology there, many children and adults aren’t getting enough vitamin D, and it could lead to serious health consequences. Dr. Holick’s research has linked low levels of vitamin D with more than just the vitamin D deficiency disease, rickets, although the incidence of this previously considered eradicated disease in children is on the rise. According to Dr. Holick, if during childhood you are vitamin D deficient, you are also at an increased risk of developing Type I diabetes, multiple sclerosis and rheumatoid arthritis. Later in life you could be more likely to develop colon, prostate, breast and ovarian cancer. Adults deficient in vitamin D can develop osteomalacia (adult rickets), osteoporosis, and muscle weakness, increasing the risk of falls.
Although healthy levels of vitamin D can be consumed with food and supplements (see sidebar for recommended levels), Dr. Holick recommends a small amount of unprotected sun exposure so that the body manufactures its own vitamin D. He advises that light-skinned people need five to 10 minutes of sun exposure on the arms and face two to three times a week. He advises not using sunscreen until after that time. A sunscreen with a sun protection factor (SPF) of 8 diminishes the skin’s ability to make vitamin D by about 95 percent. Those with darker skin may need as much as a half-hour or longer in the sun without sunscreen to produce sufficient vitamin D. More sun exposure will not help you make any more vitamin D, and will likely cause harm. Dr. Holick encourages everyone to limit exposure to 10 minutes and use sunscreen immediately afterward.
Dermatologists are incensed with Dr. Holick’s advice. “There is no such thing as a safe tan,” says Dr. Darrell Rigel, a clinical professor of dermatology at New York University in Manhattan. Dr. Barbara Gilchrest, chairwoman of the dermatology department where Holick resigned his faculty appointment calls his research “absurd” and “schlock” science. Others point to his research funding from the tanning bed industry as a possible motivation for irresponsible advice.
The overriding concern of experts in the field of dermatology is that once permission is given for any amount of unprotected sun exposure, it leaves too much room for the possibility of overexposure. Right now the message is clear: don’t ever go out into the sun without protection. It’s simple, it’s easy, and it works. And since we can get vitamin D from food, dermatologists see that as a much safer avenue than depending on the sun.
Shedding Light
Vitamin D production is not the only health benefit of sunlight. Ultraviolet light is an effective treatment for the skin condition psoriasis. Many people find that the condition improves in the summer when they’re exposed to natural sunlight.
Sunlight and light therapy is the best known treatment for seasonal affective disorder (SAD). The depression and fatigue experienced during the dark fall and winter months is alleviated in the spring and summer as the days grow longer with sunlight.
Levels of the brain neurotransmitter serotonin are elevated with sunlight exposure. Low levels of serotonin are linked with decreased mood and depression. This link may also influence the need for pain medication in post-surgery patients. A recent study found that surgery patients in rooms with lots of natural light took less pain medication, and their drug costs ran 21% less than for equally ill patients recovering in darker rooms on the other side of the hospital building.
Keys to Safe, and Sane Sunning
If you choose to follow Dr. Holick’s advice, then make sure to limit your sun exposure to no longer than 5-10 minutes, two to three times a week, or slightly more if you are dark-skinned. There is no further benefit from longer unprotected exposure.
Otherwise, follow this important advice to avoid skin damage:
- Avoid the sun during the peak hours of UV exposure: between 10 AM and 3 PM.
- Beware of cloudy skies; harmful rays still pass through the clouds.
- Use a sunscreen with at least an SPF of 15 or higher. It should have broad spectrum protection against both UVA and UVB. Water resistant products stay on the skin longer. Reapply according to directions.
- Wear protective clothing like wide-brimmed hats that shade the neck, ears, eyes and head. Use sunglasses with 99-100% UV protection. Lightweight clothing that covers your arms, shoulders, back, chest and legs will give sun protection, as well as the new high-tech clothing with SPF protection built in.
- Tanning beds are just as harmful as the sun itself. Tanning pills or spray-on tans do not give any sun protection. Be an informed consumer.
Daily Vitamin D Recommendations
For children 2 months - 18 years, the American Academy of Pediatrics recommends 200 IU of vitamin D daily.
For adults, the Institute of Medicine recommends daily Vitamin D intake as follows:
- 18 – 50 years: 200 IU
- 51 – 70 years: 400 IU
- 71 years and older: 600 IU
Good Food Sources of Vitamin D
| Food: |
Amount of Vitamin D (IU) |
| Cod liver oil (1 Tbsp) |
1,360 |
| Mackerel (3.5 oz) |
458 |
| Salmon-Atlantic (3.5 oz.) |
278 |
| Sardines in oil, canned, drained (3.5 oz) |
270 |
| Light tuna canned in oil, drained (3.5 oz) |
236 |
| Light tuna canned in water, drained (3.5 oz) |
160 |
| Milk fortified with vitamin D (1 cup) |
99 |
| Balance Bar |
80 |
| Cod-Atlantic (3.5 oz) |
56 |
| Large whole egg |
26 |
| General Mills Total Corn Flakes Cereal (1 cup) |
26 |
Citations
Holick MF. Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. Am J Clin Nutr 2004;79:362-71.
Han A and Maibach HI. Management of acute sunburn. Am J Clin Dermatol 2004;5:39-47.
Yours in a Good Mood,
Dr. Susan Kleiner