Sunlight and our health

Sun exposure can lead to:

• Improved bone health and prevention of osteoporosis, osteomalacia, and rickets.
• Reduced risk of heart disease, stroke, and breast, colon, and other cancers.
• Alleviation of skin disorders.
• Decreased risk of autoimmune disorders, including multiple sclerosis, type 1 diabetes mellitus, and rheumatoid arthritis.
• Enhanced mental health and lessening symptoms of seasonal affective disorder, premenstrual syndrome, and depression.

Vitamin D

The best-known benefit of sunlight is its ability to boost the body’s vitamin D supply; most cases of vitamin D deficiency are due to lack of outdoor sun exposure. At least 1,000 different genes governing virtually every tissue in the body are now thought to be regulated by 1,25-dihydroxyvitamin D₃ (1,25[OH]D), the active form of the vitamin, including several involved in calcium metabolism and neuromuscular and immune system functioning.

Risks

Whereas skin cancer is associated with too much UVR exposure, other cancers could result from too little. Living at higher latitudes increases the risk of dying from Hodgkin lymphoma, as well as breast, ovarian, colon, pancreatic, prostate, and other cancers, as compared with living at lower latitudes. 

Moreover, although excessive sun exposure is an established risk factor for cutaneous malignant melanoma, continued high sun exposure was linked with increased survival rates in patients with early-stage melanoma in a study reported by Marianne Berwick, an epidemiology professor at the University of New Mexico, in the February 2005 Journal of the National Cancer Institute. Holick also points out that most melanomas occur on the least sun-exposed areas of the body, and occupational exposure to sunlight actually reduced melanoma risk in a study reported in the June 2003 Journal of Investigative Dermatology.

As with multiple sclerosis, there appears to be a latitudinal gradient for type 1 diabetes, with a higher incidence at higher latitudes. A Swedish epidemiological study published in the December 2006 issue of Diabetologia found that sufficient vitamin D status in early life was associated with a lower risk of developing type 1 diabetes. There is also a connection with metabolic syndrome, a cluster of conditions that increases one’s risk for type 2 diabetes and cardiovascular disease.

Protection

To determine the potential link between sun exposure and the protective effect in preventing hypertension, Rolfdieter Krause of the Free University of Berlin Department of Natural Medicine and colleagues exposed a group of hypertensive adults to a tanning bed that emitted full-spectrum UVR similar to summer sunlight. Another group of hypertensive adults was exposed to a tanning bed that emitted UVA-only radiation similar to winter sunlight.

After three months, those who used the full-spectrum tanning bed had an average 180% increase in their 25(OH)D levels and an average 6 mm Hg decrease in their systolic and diastolic blood pressures, bringing them into the normal range. In constrast, the group that used the UVA-only tanning bed showed no change in either 25(OH)D or blood pressure.

These results were published in the 29 August 1998 issue of The Lancet. According to Krause, who currently heads the Heliotherapy Research Group at the Medical University of Berlin, a serum 25(OH)D level of at least 40 ng/mL should be adequate to protect against hypertension and other forms of cardiovascular disease (as well as cancers of the prostate and colon).

William Grant, who directs the Sunlight, Nutrition, and Health Research Center, a research and education organization based in San Francisco, suspects that sun exposure and higher 25(OH)D levels may confer protection against other illnesses such as rheumatoid arthritis (RA), asthma, and infectious diseases. Grant says:

Vitamin D induces cathelicidin, a polypeptide that effectively combats both bacterial and viral infections. This mechanism explains much of the seasonality of such viral infections as influenza, bronchitis, and gastroenteritis, and bacterial infections such as tuberculosis and septicemia.Some reports, including an article in the October–December 2007 issue of Acta Medica Indonesiana, indicate that sufficient 1,25(OH)D inhibits induction of disease in RA, collagen-induced arthritis, Lyme arthritis, autoimmune encephalomyelitis, thyroiditis, inflammatory bowel disease, and systemic lupus erythematosus.

Michael Zasloff, Journal of Investigative Dermatology (2005):

"Exposure of human skin to UVB light can stimulate expression of the antimicrobial peptide LL 37, likely through a chain of events that involves Vitamin D. The discovery that sunlight, through the mediation of Vitamin D, activates an arm of innate immunity within the skin of man could have far-ranging implications with respect to our understanding of certain human skin conditions and their treatment."

Antimicrobial peptides are widely expressed throughout nature and provide a means by which multicellular organisms can defend themselves rapidly against microbial assault (Zasloff, 2002).

Recommendations

National Institutes of Health Office of Dietary Supplements, "Dietary Supplement Fact Sheet - Vitamin D:

Your body makes vitamin D when you are exposed to the ultraviolet B (UVB) rays in sunlight. You probably need from 5 to 30 minutes of exposure to the skin on your face, arms, back or legs (without sunscreen) twice every week.

To maximize protection against cancer, Grant recommends raising 25(OH)D levels to between 40 and 60 ng/mL. Research such as that described in Holick’s August 2006 Journal of Clinical Investigation article indicates that simply keeping the serum level above 20 ng/mL could reduce the risk of cancer by as much as 30–50%.

Cedric F. Garland, a medical professor at the University of California, San Diego, says that maintaining a serum level of 55–60 ng/mL may reduce the breast cancer rate in temperate regions by half, and that incidence of many other cancers would be similarly reduced as well. 

Holick, Vieth, and many other experts now make a daily recommendation: 4,000 IU vitamin D₃ without sun exposure or 2,000 IU plus 12–15 minutes of midday sun. They say this level is quite safe except for sun-sensitive individuals or those taking medications that increase photosensitivity.

I would say: be on the sun for half an hour a day! :)

Brief, repeated exposures are more efficient at producing vitamin D. Longer sun exposures cause further sun damage to skin and increase the risk of photo-aging and skin cancer, but do not increase vitamin D production.

Sun exposure

The healing rays of natural sunlight (that generate vitamin D in your skin) cannot penetrate glass. So you don't generate vitamin D when sitting in your car or home. It is impossible to generate too much vitamin D in your body from sunlight exposure: your body will self-regulate and only generate what it needs.

By getting 10-15 minutes of sun at least three times a week with some SPF on your hands and face in the late morning or mid afternoon will give your body natural Vitamin D. Your body will make this to any where from 1,000 IU to 3,000 IU.

People with dark skin pigmentation may need 20-30 times as much exposure to sunlight as fair-skinned people to generate the same amount of vitamin D. That's why prostate cancer is epidemic among black men.

Nutrition

It is nearly impossible to get adequate amounts of vitamin D from your diet. Sunlight exposure is the only reliable way to generate vitamin D in your own body. More than 90% of the vitamin D requirement for most people comes from casual exposure to sunlight. Very few foods naturally contain vitamin D. Mushrooms are the only vegan nutritional source of vitamin D. A little more than 1/4 cup is equal to 400 IU of Vitamin D.

Sufficient levels of vitamin D are crucial for calcium absorption in your intestines.

Vitamin D is "activated" in your body by your kidneys and liver before it can be used. Having kidney disease or liver damage can greatly impair your body's ability to activate circulating vitamin D.

Melatonin

As diurnal creatures, we humans are programmed to be outdoors while the sun is shining and home in bed at night. This is why melatonin is produced during the dark hours and stops upon optic exposure to daylight. Production of melatonin by the pineal gland is inhibited by light and permitted by darkness. For this reason melatonin has been called "the hormone of darkness"This pineal hormone is a key pacesetter for many of the body’s circadian rhythms. It also plays an important role in countering infection, inflammation, cancer, and auto-immunity, according to a review in the May 2006 issue of Current Opinion in Investigational Drugs. Finally, melatonin suppresses UVR-induced skin damage, according to research in the July 2005 issue of Endocrine.

When people are exposed to sunlight or very bright light in the morning, their nocturnal melatonin production occurs sooner, and they enter into sleep more easily at night. Melatonin production also shows a seasonal variation relative to the availability of light, with the hormone produced for a longer period in the winter than in the summer. The melatonin rhythm phase advancement caused by exposure to bright morning light has been effective against insomnia, premenstrual syndrome, and seasonal affective disorder (SAD).

Besides its function as synchronizer of the biological clock, melatonin also exerts a powerful antioxidant activity. The discovery of melatonin as an antioxidant was made in 1993.

Serotonin

The melatonin precursor, serotonin, is also affected by exposure to daylight. Normally produced during the day, serotonin is only converted to melatonin in darkness. Whereas high melatonin levels correspond to long nights and short days, high serotonin levels in the presence of melatonin reflect short nights and long days (i.e., longer UVR exposure). Moderately high serotonin levels result in more positive moods and a calm yet focused mental outlook. It was recently found that mammalian skin can produce serotonin and transform it into melatonin, and that many types of skin cells express receptors for both serotonin and melatonin.

Melatonin researcher Russel J. Reiter of the University of Texas, Health Science Center:

“The light we get from being outside on a summer day can be a thousand times brighter than we’re ever likely to experience indoors. For this reason, it’s important that people who work indoors get outside periodically, and moreover that we all try to sleep in total darkness. This can have a major impact on melatonin rhythms and can result in improvements in mood, energy, and sleep quality.”

For people in jobs in which sunlight exposure is limited, full-spectrum lighting may be helpful. Sunglasses may further limit the eyes’ access to full sunlight, thereby altering melatonin rhythms. Going shades-free in the daylight, even for just 10–15 minutes, could confer significant health benefits.

Endorphins

UVR increases blood levels of natural opiates called endorphins. Melanocytes (pigment cells) in human skin express a fully functioning endorphin receptor system, according to the June 2003 Journal of Investigative Dermatology.

 Controversy

The UV Advantage, a book by Dr Michael Holick (Boston University School of Medicine, MA) created a storm of controversy and has also led to a call for his resignation. In the book, Holick claims that moderate exposure to the sun has powerful health benefits and that current advice to avoid the sun has led to an epidemic of vitamin-D deficiency.

Holic:

"Many who practice dermatology and their supporters in the sunscreen industry have scared the public right out of the sun, the best way to produce the vitamin D that the body needs. These naysayers have ignored the mountain of peer-reviewed science that demonstrates that moderate exposure to natural or artificial sunlight has a powerful, beneficial impact on health."

"There are important medical consequences of this continuing rhetorical campaign of fear and exaggerated claims. There is no doubt vitamin D is the best way for the body to control abnormal cell growth."

Dr Robert Heaney (Creighton University, Omaha, NE):

"Holick provides a much-needed antidote to the scare tactics of the skin mafia."  

Dr John Adams (University of California, Los Angeles and Cedars-Sinai Medical Center) says that the Holick's  book: "provides the clinical community with the first balanced, unbiased view of the benefits and dangers of sunlight exposure in the last 50 years."

Dr Jim Leyden (University of Pennsylvania, Philadelphia) has known Holick for 25 years and describes him as "an incredibly creative person who's made some really fundamental observations and discoveries in several areas," adding, "He's ahead of his time."

Holick:

"It's easier for them to say just don't be exposed to sunlight instead of providing the thoughtful, intelligent recommendation that maybe a little sun is good for you. I am not advocating a return to the baby-oil and sun-reflector tanning days of the past. This is about spending a few minutes in natural or artificial sunlight several times a week—without sunscreen—to satisfy your body's vitamin requirement. It is not about damaging the skin."

Dermatologist Rigel pointed out that the US Department of Health and Human Services has declared UV radiation as a known carcinogen:  "American dies every hour from melanoma, the most serious form of skin cancer. The fact is, skin cancer is increasing at an alarming rate, and scientific research confirms that our best defense is avoiding excessive, unprotected sun exposure. Normal vitamin-D levels are easily maintained through routine daily activities (even when wearing sunscreen) and a normal diet, so supplemental vitamin-D tablets are typically not needed."

Holick strongly disagrees:

"It is improper for unenlightened dermatologists, many of whom know little about human nutrition, to suggest that consumers can get all their vitamin D from diet. It would require drinking 10 glasses of milk or fortified orange juice every day. The literature is clear. Adequate amounts of vitamin D cannot be achieved at the current low levels set years ago by the Institute of Medicine—200 IU a day. Consumers should routinely be taking 5 times that amount, 1000 IU a day of vitamin D. It is misleading to suggest that nutritional supplementation is the answer. It is not practical to get our daily 1000 IU of vitamin D from popping a pill. More important, supplements do not provide the same benefits as sunshine, and if taken in too large a dose, they can cause vitamin-D toxicity."

Sungazing

Sungazing is a practice that includes gazing at the sun for nourishment or as a spiritual practice.

Proponents of sungazing claim increased energy levels and decreased appetite. There is a lack of scientific studies confirming it.

Hira Ratan Manek, also known as HRM, argues that one must practice sungazing for a period of nine months, after which gazing at the sun need not be continued, and the practitioner need never take food again. He and his followers practise sungazing and argue that they receive nourishment (or other benefits) from sungazing, often to either complement or replace eating food, a form of inedia ("breatharianism"). He also claims that since 1995 he has lived on sunlight without a need for solid food, and that he does not experience the food cravings or lethargystarvation or a lack of nutrients. His wife has stated that he drinks small amounts of coffee, tea, fruit juices, and buttermilk.

Sungazers claim their eyes are capable of converting sunlight into energy for their bodies and that this is similar to photosynthesis.

Sungazing is also part of the Bates method, an alternative therapy intended to improve eyesight. Ophthalmologists do not regard the method as useful.

Dangers

Looking directly at the sun may cause blindness or severe damage to the eye. Solar retinopathy (damage to the eye’s retina due to solar radiation) and blindness to varying degrees and persistence frequently result from sungazing during a solar eclipse. Although vision loss due to this damage is generally reversible, permanent damage and loss of vision have been reported. Eye care professionals advise patients to avoid looking directly at the sun.

Thanks for the interesting article Lena.

My husband and I have been sungazing for the past few months and absolutely LOVE it..   I researched it carefully before trying and it just felt right to do.  So far I have noticed I go into a very deep sleep after years of sleeping lightly.  You feel really connected with your environment and the universe.  My eyes are a lot stronger already, and I am hoping to improve my eyesight with it. 

Sungazing blends so nicely with being a Fruitarian...it all just feels totally natural.

xx Diana