You hear much about sunlight causing skin cancer. Indeed, solar ultraviolet radiation seems to account for approximately 93 percent of skin cancers and about half of lip cancers.1 However, there are many scientifically established physiological, cancer-protecting benefits of sunlight as well. A review of 8 studies from 100 countries shows strong inverse correlations with solar UVB for 15 types of cancer: bladder, breast, cervical, colon, endometrial, esophageal, gastric, lung, ovarian, pancreatic, rectal, renal, and vulvar cancer; and Hodgkin’s and non-Hodgkin’s lymphoma.2
For example, individuals living in northern latitudes (and thus lower vitamin D production) have a substantial greater risk of getting 15 types of cancer such as breast, stomach, colon cancer, and lymphomas—just to name a few. For example, men living in Michigan, Connecticut, and Washington had colon cancer rates 50-80% higher than men living in New Mexico.3 Researchers from the University of California also found in their studies that individuals with optimal levels of serum vitamin D, generated through modest sunlight exposure, also had a 50% lower incidence of colorectal cancer.4 The Cleveland Clinic reports that men with high levels of vitamin D were half as likely to develop the aggressive form of prostate cancer than were those who had lower levels of vitamin D.5 So how does sunlight protect from cancer? As we shall later see the answer largely lies in vitamin D. Exposure of our skin to sunlight produces vitamin D.
- Nutritionist epidemiologists estimate that 50% of North Americans have an insufficient amount of vitamin D.6
- Elderly people’s ability to get vitamin D from sun exposure is very greatly reduced. Therefore, they must get vitamin D from fortified foods or supplements.
- Although faired-skin people can get enough vitamin D by being in the sun for 10-15 minutes a day, this is not true for dark-skinned individuals. They may need to be in sunlight for 30 to 45 minutes to obtain vitamin D.
- Studies show that dark-skinned individuals, breast fed babies, those with kidney disease, obesity, or those living in northern latitudes have significant risk for vitamin D deficiency.
- Sunscreen blocks our ability to get vitamin D through sunlight.
Sunlight Spawns Vitamin D Production
Individuals may get up to 90% of their vitamin D from the sunlight. The human body synthesizes Vitamin D from the ultraviolet rays in sunlight. These rays activate the cholesterol in our skin into a form of Vitamin D which is then absorbed into the blood through the capillaries and transported to the liver. It is then stored in the liver where it undergoes a biological change before it is transported to the kidneys where it is changed into its ‘supercharged’ form (calcitriol).
Super-charged D fights cancer by several different biological mechanisms. First, it improves the efficiency of natural killer cells to destroy cancer cells and inhibits the proliferation of cancer cells. It also promotes apoptosis (programmed death) of cancer cells.7 This is amazing because cancer cells have a higher resistance to apoptosis. Additionally, vitamin D inhibits the development of new blood vessels (angiogenesis) that feed the tumor site, thus slowing the growth of the tumor. I am not saying that vitamin D can prevent or cure all cancers, but certainly individuals who have an increased risk of developing cancer should have their vitamin D levels monitored! If we have insufficient amounts of vitamin D in our serum, we need to build it up with adequate sunshine and wise supplementation.
Preserves Bone and Muscle Health
By giving us vitamin D, sunshine helps to strengthen our teeth and bones, especially important in today’s aging society because 90% of the elderly who fall break bone. Moderate amounts of Vitamin D can help protect against this by building bone density. Vitamin D promotes bone health also by maintaining Parathyroid Hormone (PTH). PTH stimulates bone building activity. Sufficient levels of vitamin D also help to maintain muscle mass and strength. Exercise, especially in the sunlight, increases the number and the volume of powerhouses in the muscle cells. On the other hand, vitamin D deficiency is associated with muscle weakness, diffuse muscle pain, and atrophy of fast-twitch muscle fibers that give us speed. Evidence suggests that sunbathing may reduce pain from fibromylagia.8
Rev Up Your Metabolism
You’ve heard of your thyroid hormone, so essential for the metabolism of each cell in your body. If you are low in thyroid, your energy and mental alertness decline and your weight often increases. Vitamin D needs to be present at sufficient levels in the cells in order for the thyroid hormone to actually affect that cell and keep your metabolism running smoothly.
Sunlight kills germs but it does more than that. By exposing our skin to sunlight, our body becomes better able to resist infections. Studies show that just 10 minutes of sunshine two times a week is enough to help reduce the number and severity of colds we catch. Sunshine, via Vitamin D, increases the number of germ-killing compounds found in special white blood cells that destroy viruses. At the same time regular exposure to sunshine and vitamin D helps to balance the different components of the immune system so as to lower the risk of autoimmune diseases in which the immune system attacks the organs and tissues of the body. By balancing the different immune cells, Vitamin D also helps to protect us from allergies.
Resting heart rate, blood pressure, and respiration rates all drop after a mild sunbath. The sun’s infrared rays improve circulation to the skin while they help the blood vessels to dilate.9 Regular exposure to the sun and vitamin D helps to suppress a blood pressure elevating enzyme and helps to reduce serum cholesterol levels. Sunlight increases nitric oxide production. In moderation, this valuable molecule improves circulation by opening up blood vessels and consequently reduces the risk of undesirable clot formation.
The Connection between Sunshine, Mood, and Vitamin D
Sunlight increases endorphins, chemicals in our brain that make us feel good. Not only that but it helps the brain produce serotonin, a neurotransmitter important for self-control and positive outlook. No wonder that those patients with hospital beds by a sunny window had shorter stays than patients facing no window at all. When this exposure to sunlight is combined with regular aerobic exercise, the production of serotonin may be even better. One important caveat here: Vitamin D supplementation usually increases the blood plasma level of Vitamin D but cannot substitute for sunshine in increasing serotonin.
Protect Your Skin
According to the Skin Cancer Foundation, one out of every five Americans will develop skin cancer during his or her lifetime.10 There are more new cases of skin cancer each year than the combined yearly incidences of breast, prostate, lung, and colon cancers. Basal cell carcinoma is the most common form of skin cancer affecting 800,000 Americans each year. Individuals with fair skin, light hair, and blue, green, or gray eyes are at the highest risk. Those whose occupations require long hours outdoors or who spend extensive leisure time in the sun are also more likely to develop this type of cancer. Chronic exposure to sunlight is the cause of most basal cell carcinomas that occur most frequently on the exposed parts of the body: (face, ears, neck, scalp, shoulders, and back). Basal cell carcinoma often shows itself as an open sore, a reddish patch, a shiny bump, a pink growth, or a scar-like area.
Melanoma is the most serious form of skin cancer. However, if diagnosed and removed while localized to the superficial layer of the skin, it is almost 100% curable. Once the cancer advances and metastasizes (spreads) to other parts of the body, treatment is difficult. Melanomas are usually black or brown and have irregular borders.
Enjoying Sunlight—A Balanced Approach
- Build up a tan gradually. Avoid getting too tanned and skip the tanning booths.
- Avoid exposure to sunlight during the hottest part of the day (10am – 5pm).
- Apply broad-spectrum sunscreen after at least 15 minutes of exposure to the sun’s rays—sunscreen blocks the absorption of vitamin D into the skin. If you are at risk for skin cancer, apply before you go out in the sunlight. Just take a vitamin D supplement. Your sunscreen should provide both uva and uvb protection. You do need to reapply it every couple of hours. Water, sand, and snow intensify the burning power of the sun.
- Wear a broad-rimmed hat.
- Wear sunglasses with good ultraviolet protection.
- Consider clothing with ultraviolet protection.
- Eat a diet rich in antioxidants. Dark green leafy vegetables and carotenoids found in orange fruits and vegetables protect the skin.
- Limit fat consumption. A high-fat diet encourages the development of cancer.
- Eat foods containing natural COX-2 inhibitors.Too much ultraviolet light (UVB) increases COX-2 activity in the skin which encourages inflammation and other abnormalities. Red grapes, blueberries, garlic, and turmeric possess natural COX-2 inhibitors.
- Don’t smoke. Smoking triples the risk of squamous cell carcinoma, a common skin cancer.11
- Be able to identify potential skin cancer lesions.
If you are in the sun for long periods of time, have a thorough skin examination from your doctor at least twice a year to check for any skin abnormalities. Between times have your spouse or a friend check for any skin discoloration. We want to get the benefits of the sunlight without getting skin cancer!
Contributed by wildwoodhealth.org
Gallager RP, Ultraviolet radiation, Chronic Dis Can., 1010,29 Suppl 1:51-68 ↩
Grant, WB, Ecological Studies of the UVB-Vitamin D-Cancer Hypothesis. Anticancer Res. 2012 Jan; 32(1):223-36. ↩
DeNoon, D.J., Getting some sun may fight blood cancer protective effect from vitamin D suspected. WebMDHealth News, March 31, 2004, www.webmd.com/cancer/news/20040331/getting-some-sun-may-fight-blood-cancer. ↩
Nedley, N., Proof Positive, Nedley Publishers, 1998, p. 498. ↩
Study sheds light on cutting risk of prostate cancer; 15 minutes in sun linked to protective levels of vitamin D, Feb 19, 2005, www.redorbit.com/news/health/129282/study_sheds_light_on_cutting_risk ↩
Shils, M., et al, (Ed.), Modern Nutrition in Health and Disease, 10th edition, Lippincott, Williams, and Wilkins, 2005. ↩
Fleet, J.C., Molecular actions of vitamin D contributing to cancer prevention. Mol Aspects Med, 29(6):388-96, 2008, epub Aug 8, 2008, review. ↩
Feldman SR, et al. Ultraviolet exposure is a reinforcing stimulus in frequent indoor tanners. J Am Acad Dermatol. 2004;51:45–51. ↩
Opländer C, et al. Whole body UVA irradiation lowers systemic blood pressure by release of nitric oxide from intracutaneous photolabile nitric oxide derivates. Circ Res. 2009;105:1031–40. ↩
American Society Of Clinical Oncology (2000, December 29). Smoking Triples Risk Of A Common Type Of Skin Cancer. ScienceDaily. ↩