Health Benefits of Vitamin D
Vitamin D is one of the body's most essential nutrients as it (i) plays a key role in the absorption of calcium for the maintenance of health bones, (ii) promotes muscle development and muscle strength, (iii) appears to play a role in cardiovascular health, metabolic health, immune system strength and cancer prevention, and (iv) plays a positive role in mental health and depression avoidance. As Vitamin D receptors have been discovered in most cells of the body, expanded research on other health benefits of Vitamin D are being examined. The role of Vitamin D in health and disease is continually expanding.
Recent research has found that Vitamin D increases hormone levels in men. See also Tips to Increase Testosterone Naturally
On the other hand, excessive exposure to the sun has been proven to cause certain types of skin cancer later in life. The purpose of this article is to educate you on the essential health benefits and process of Vitamin D production intitiated from the Sun and the risks of sun induced skin damage and cancer.
Skin Vitamin D Synthesis from the Sun, Food Sources of Vitamin D
A. The SUN! The major source of Vitamin D for most humans is from the skin's exposure to the ultraviolet B (UVB) rays of sunlight. Sunlight contributes on average over 90% of our Vitamin D!
B. Food Sources. Only a few food sources naturally contain appreciable sources of Vitamin D3 that have an impact on dietary intake: fish, fish liver, fish liver oils, fatty fish, mushrooms, egg yolks and beef liver. Mushrooms are the only vegan source of Vitamin D. Fish liver oils, such as cod liver oil, appear to have the greatest concentration of Vitamin D containing 1 Tbs. (15 ml) provides 1360 IU (90.6 IU/ml). Fish should be consumed that live only in uncontaminated waters.
Oily fish such as catfish, salmon, sardine, tuna, mackerel and blue fish are excellent sources of Vitamin D3. A serving of wild salmon can have up to 1000 IU of Vitamin D3. NOTE, farm raised salmon have only about 1/4 the amount of Vitamin D as wild salmon. The disparity of Vitamin D content between farm raised salmon and wild salmon is very interesting. Assuming all other things being equal, farm raised salmon don't have the natural survival challenges (ie. currents, swimming long distances, swimming upstream, spawning, chasing food, eluding predators such as Orca whales, seals and sea lions) as do wild salmon. Are wild salmon more vital and stronger than farm salmon? Undoubtedly! By way of analogy are people more physically active more vital than sedate inactive people? Do more physically active people have higher demands for Vitamin D?
Some countries practice fortification of certain foods with Vitamin D3, most often milk, yogurt, butter and cheese. Orange juice is also sometimes fortified with Vitamin D3.
Fish and fish oils are also a vital source of Omega-3 Fatty Acids which are esential to good health. See Health Benefits of Omega-3 Fatty Acids
C. Vitamin D Supplements. Vitamin D supplements in different dosages are widely and inexpensively available in most countries. While with any supplement there is a concern about toxicity, studies thus far have indicated Vitamin D supplements are safe.
Vitamin D Synthesis and Metabolism
Our body's absorption of energy from sun to create Vitamin D is one of the many wonders of the human body. It's a complex process, but an important process to appreciate for people tuned into optimum health and peak performance, like athletes.
Our body's absorption of energy (photons) from the sun to create Vitamin D may be as significant to animal life (all animals generate Vitamin D from the sun) as the process of photosynthesis is necessary for plant life. The process of plant photosynthesis also uses the energy from the sun to convert carbon dioxide and water into organic compounds, especially sugars. In photosynthesis, plants release oxygen as a waste product. As well as maintaining the normal level of oxygen in the atmosphere, nearly all life either depends on photosynthesis directly as a source of energy, or indirectly as the ultimate source of the energy in their food.
Vitamin D Synthesis and Metabolism. The body's process of making Vitamin D begins in the skin. The skin contains 7-dehydrocholesterol (7-DHC), which is a derivative of cholesterol. 7-DHC absorbs photons from UVB rays of the sun that occur within the 280-320 nm wavelength. This synthesis creates pre-Vitamin D. Vitamin D metabolism then occurs in the liver where it is stored until it is needed. However, from the liver, Vitamin D then passes through the kidneys. Following the final converting step in the kidneys the physiologically active form of vitamin D is released into the blood for circulation. See Kidney Health, Red Blood Cell Production and Peak Athletic Performance
Environmental and Personal Factors Impacting Skin Vitamin D Synthesis
As the skin's exposure to the sun's ultraviolet B radiation is our bodies major source of Vitamin D, it is important to know and understand the various factors that impact this Vitamin D synthesis caused by the sun. Here are the key factors that influence Vitamin D synthesis:
1. Content of 7-dehydrocholesterol (7-DHC) in the Skin. 7-DHC content in the skin is a primary factor in the occurance of Vitamin D synthesis.
2. UVB Wavelength. Vitamin D synthesis occurs primarily in the UVB wavelength between 280 nm and 320 nm which impacts the energy of the photons which cause Vitamin D synthesis.
3. Solar Zenith Angle, a function of Latitude, Season and Time of Day. Before solar UVB can intiate Vitamin D synthesis in the skin it must traverse the atmosphere. The main determinant of available UVB is the angle of the sun. The more directly overhead the position of the sun the more UVB is available to for Vitamin D synthesis. Latitude, season and time of day are the three factors impacting available UVB. The higher the latitude, the closer to winter season and the further from mid day, the less UVB is available for Vitamin D synthesis. Conversly, the the closer to the equater, the summer season and mid day, the more UVB is available. The more UVB available, the less time in the sun is needed to meet Vitamin D needs from synthesis.
For instance, at the latitude of Seattle, Boston, München, Hobart and Christchurch, Vitamin D synthesis occurs between about 7am to 5pm. In the spring and fall, the window for Vitamin D synthesis shortens to about 9am to 3pm. In winter the window for Vitamin D synthesis decreased altogether. In summer, morning is a good time to get sun for Vitamin D production with low risk for UV skin damage.
4. Altitude. As higher altitudes result in shorter distances and less atmosphere for UVB to pass through, more UVB is available to reach the skin for Vitamin D synthesis. The amount of available UVB increases by 4% for every 300 meters (984 feet) of elevation gain.
5. Atmospheric Conditions. Cloud cover is a very important factor determining UVB available for Vitamin D synthesis. Lower thicker clouds have the greatest ability to decrease available UVB. Heavy cloud cover can block 99% of UVB from reaching the ground.
Airborne pollutants can significantly reduce available UVB. Tall city buildings, narrow city streets, along with the move to indoor jobs would have certainly decreased sun exposure amongst urban populations.
Snow can reflect 90% of UV radiation greatly increasing the available UVB striking the skin.
6. Skin Tone, Pigmentation. Studies show lighter skin tones have greater capacity to synthesize Vitamin D and require less UVB exposure to produce adequate levels of Vitamin D. While people in the United States in general have become increasingly Vitamin D deficient with almost half of the population Vitamin D deficient, researchers have found that more than half of African Americans were Vitamin D deficient. Darkly pigmented skin isn't as efficient at inducing Vitamin D synthesis. This is not a problem in Africa where there is plenty of sun, but often translates into Vitamin D deficiency in more northern latitudes where sunshine is more limited.
7. Body Mass Index (BMI). Research confirms people with a BMI >30 has an effect on Vitamin D levels as obese people generally have lower levels of Vitamin D and a slightly reduced rated of UVB induced production of Vitamin D.
8. Age. The capacity for Vitamin D synthesis is based upon the availability of 7-DHC in the skin. Aging generally reduces the content of 7-DHC in the skin and thus the potential for Vitamin D production. The 7-DHC skin content seems to reduce by about one half between the age of 20 and 90. Vitamin D supplements, a diet rich in Vitamin D and increased sun exposure, but not excessive sun exposure, is recommended with aging.
9. Sun Avoidance, Sunscreen and Clothing. It's been estimated that the correct application of sunscreen, which blocks UVB rays, with an SPF of 8 reduces the skins Vitamin D production by over 90% and sunscreen with an SPF of 15 reduces Vitamin D production by 99%. Sun avoidance (as in staying indoors) and clothing and hats can significantly reduce sun induced Vitamin D production.
Risks of Vitamin D Deficiency
1. Poor Bone and Muscle Health. As Vitamin D plays an essential role to calcium absorption, weak bones and muscle can occur when Vitamin D is deficient. Calcium and Vitamin K are also essential to bone health. See Natural Sources of Calcium. See also Natural Sources of Vitamin K.
2. Multiple Sclerosis. Research indicates the people who are Vitamin D deficient at an early age are at greater risk of developing multiple sclerosis in later years of life. Some studies have strongly indicated that pre-natal Vitamin D is an key risk factor for developing multiple. sclerosis later in life. There is a greater risk of multiple sclerosis living in northern latitudes compared to living near the equator. Women who supplement their diet with Vitamin D are proven to have a lower risk of multiple sclerosis.
3. Depression. Sunshine and Vitamin D levels have been proven to positively impact mental health and help fight and prevent depression. See Tips to Beat Depression Naturally
4. Cancer Prevention. As part of the paradox between DNA skin damage due to sun overexposure, and the health benefits of Vitamin D, researchers have found that chronic sun exposure (and hence consistently high levels of Vitamin D) confers protection against Melanoma. High Vitamin D levels are also now believed to play a role to protect against stomach, colorectum, liver, gallbladder, pancreas, lung, breast, prostate, bladder and kidney cancers. Although sun exposure may confer protective effect for melanoma and many other cancers, it simultaneously promotes squamous cell and and basal cell carcinoma.
5. Tuberculosis. Sunshine and Vitamin D have been proven to help fight and cure tuberculosis.
6. Diabetes Type 2. Vitamin D Deficiency has been linked to pre-diabetes. People with low vitamin D status tend to have higher fasting blood sugar levels, impaired glucose tolerance, higher rates of metabolic syndrome and a higher incidence of pre-diabetes. Maintaining sufficient Vitamin D levels may help prevent Type 2 Diabetes.
7. Alzheimer's Disease. Vitamin D defiency has been strongly linked to Alzheimer' Disease. A team of researchers has uncovered the intracellular mechanisms regulated by vitamin D3 that may help clear amyloid-beta from the brain, the hallmark of Alzheimer's disease. Indications are Vitamin D protects the brain through the immune system and that recommended blood levels of the 25-hydroxy vitamin D should be maintained in all seasons including winter when the sun is not helping to produce vitamin D in the skin.
Sun Overexposure, Photoprotection and Healthy Skin
The effects of sun exposure are paradoxical with (i) skin cell DNA damage risk increasing with excessive sun exposure over decades on the one hand, and (ii) the essential health needs of Vitamin D synthesis from sun exposure on the other. In fair skinned individuals, maximum possible Vitamin D synthesis can occur within a few minutes of mid day summer sun exposure. Yet, Over the course of two decades, Vitamin D levels have dramatically decreased among Americans. Since sunlight is the body's major source of Vitamin D, increases in sunscreen, sun avoidance, and overall decreased outdoor activity, while successful in reducing skin cancers, has probably reduced vitamin D levels in the population.
Recommended Dosage of Sun Exposure . Implementing guidelines suggesting sun exposure duration for sufficient Vitamin D3 production is difficult due to the the complex and various factors that impact Vitamin D synthesis. As such, the medical profession believes at this point that no recommendation on sun exposure can be made that is both safe and accurate enough for general public usage. It seems many in the medical profession consider the risk of skin cancer from unprotected sun exposure outweighs any increase Vitamin D levels that may occur, and recommend Vitamin D supplements.
Sun Overexposure and Skin Aging. Excessive sun exposure over years can prematurely age skin.
Eye Health. UV rays can also cause damage to the eyes. Sunglasses can protect eyes from sun damage. The ideal pair of sunglasses would block all UV rays while not sacrificing the transmission of visible light.<-- back to top
Articles on Vitamin D
Vitamin D Metabolism, Bodo Lehmann & Michael Meuher, Department of Dermatology, Carl Gustov Carus Medical School, Dresden University of Technology, Dresden, Germany, Dermatologic Therapy 2010
Vitamin D and Innate Immunity, Jeremiah Miller & Richard Gallo, Division of Dermatology, Departments of Medicine and Pediatrics, University of California at San Diego, Dermatologic Therapy 2010
Health Effects of Vitamin D, Heike Bischoff-Ferrari, Center on Aging and Mobility, University of Zurich and Department of Rheumatology and Institute of Physical Medicine, Zurich, Switzerland, Dermatologic Therapy 2010
Photoprotection: a Review of the Current and Future Technologies, Steven Wang, Yevgeniy Balagula & Uli Osterwalder, Memorial-Sloan-Kettering Cancer Center, New York, Ciba, Inc. Basel, Switzerland, Dermatologic Therapy 2010
Effects of Ambient Sunlight and Photoprotection on Vitamin D Status, Joseph Diehl & Melvin Chiu, Division of Dermatology, Departments of Medicine at UCLA and Division of Dermatology Service, West Los Angeles Veterans Administration Medical Center, Dermatologic Therapy 2010
Phys Ed: Can Vitamin D Improve Your Athletic Performance?, Gretchen Reynolds, New York Times
Many Americans Fall Short on Their Vitamin D, Steven Reinberg, HealthDay
Low Prenatal Sunlight Exposure May Increase Multiple Sclerosis Risk, Pauline Anderson and Laurie Barclay, MD, Medscape
Vitamin D 'affects more than 200 genes', John Von Radowitz, Sydney Morning Herald
Effects of Vitamin D Supplementation on Testosterone Levels in Men, S. Pilz, Medical University of Graz, Austria, National Institute of Health
Vitamin D and Pre-Diabetes, Livestrong
Studies Show How Vitamin D3 Helps Clear Amyloid in AD (Alzheimer's Disease), Megan Brooks, Medscape