Science | Sunshine Health

The Science

The Longstanding Advice on Sun Exposure From the Medical Establishment is Wrong

Unfortunately, the World Health Organization (WHO), the Centers for Disease Control and Prevention (CDC), the American Academy of Dermatology and most of the rest of the medical establishment have it wrong. They misstate and exaggerate the risks of skin cancer from sun exposure and they are silent on the risks of insufficient sun exposure.

They say: Melanoma is caused by “overexposure” (they don’t define this) to the sun. They say that even a small amount of sun exposure puts you on the road to melanoma, so all sun exposure without protection should be avoided.
- 21st Century Science says: Risk of melanoma from the sun is only associated with severe sunburns (“severe” means they hurt for at least 48 hours or cause blistering or peeling). Paradoxically, non-burning sun exposure actually reduces risk of melanoma. Contrary to what “they” say, non-burning sun exposure, even in very large lifetime amounts, is not associated with increased melanoma risk.
They say: The only benefit of sun exposure is that it produces vitamin D, and this benefit can be better obtained by inexpensive vitamin D supplements without taking the risks of sun exposure.
- 21st Century Science says: Vitamin D is not the only benefit of sun exposure. Sun exposure produces nitric oxide and many other biomolecules in the human body in addition to vitamin D, all of which are needed for good health. Click HERE for a description of the biomolecules produced by sun exposure. Vitamin D supplements are not an effective substitute for sun exposure for the simple reason that vitamin d supplements do not produce nitric oxide and the other sun-produced biomolecules (other than vitamin D) and because numerous scientific studies have shown that vitamin D supplements are not an effective substitute for sufficient sun exposure.
They say: Americans should avoid intentional sun exposure.
- 21st Century Science says: 70% of all Americans are suffering from the adverse health effects of insufficient sun exposure, and need.
They say: Apply sunscreen daily if you are going to be outside, even on cloudy days.
- 21st Century Science says: Daily use of sunscreen is a very bad idea. Sunscreen blocks a significant portion of the sun’s rays needed to produce vitamin D, nitric oxide and the other biomolecules you need for good health. Sunscreen should only be used when necessary to prevent sunburn. Click HERE for the proper use of sunscreen.
They say: Seek shade if outside between 10 a.m. and 2 p.m. If your shadow is shorter than you are, seek shade.
- 21st Century Science says: Most of the health benefits of sun exposure occur between the hours of 10 a.m. and 2 p.m., so what they say is the opposite of what you should do. Try to get most of the sun exposure you need between the hours of 10 a.m. and 2 p.m.
They say: Wear sun-protective clothing, such as a lightweight and long-sleeved shirt, pants, a wide-brimmed hat and sunglasses with UV protection. For more effective sun protection, select clothing with an ultraviolet protection factor (UPF) label.
- 21st Century Science says: When you are getting the sun exposure you need, try to expose as much of your skin as possible. The more skin you expose to the sun the less time you need to spend in the sun to get the exposure you need for good health. If you are concerned about getting too much sun exposure on your face and neck, cover your face and neck with a white towel. The benefits of sun exposure are proportional to the area of your skin exposed to the sun, so you can get plenty of effective sun exposure with your face and neck covered if your arms and legs are exposed, and especially if your torso is also exposed. Clothing with a UPF label is an example of the commercial interests that benefit from “sun scare” messaging. Wearing sunglasses is a good idea, as is keeping your eyes closed when sunbathing. A wide-brimmed hat is a good idea if you are concerned about getting to much sun exposure on your face and neck.
They say: Getting a base tan doesn’t help protect against sunburn. A tan is just skin damage and should be avoided.
- 21st Century Science says: A tan is part of the human body’s natural acclimatization to sun exposure and provides significant protection against subsequent sunburn. A good tan has an SPF of 24 and doesn’t wash off or need to be reapplied. Click HERE for Experiment on SPF of a Tan.
They say: Most Americans get all the sun exposure they need for good health from their normal daily activities.
- 21st Century Science says: 70% of Americans do not get all the sun exposure they need for good health.
They say: Children are particularly vulnerable to UV radiation. Parents should take special care to protect them from solar UV radiation. Babies under 12 months should always remain in the shade.
- 21st Century Science says: Children and babies, just like adults, also need enough sun exposure to maintain their 25(OH)D levels at 30 ng/mL or more. Parents should take special care to protect their children from getting sunburned, while at the same time ensuring they get enough sun exposure to maintain their 25(OH)D levels at 30 ng/mL or more. As children spend more time in the sun, their tans will permit them to spend more and more time in the sun without getting sunburned. It is not only 70% of all American adults that have 25(OH)D less than 30 ng/mL – 70% of all American children also have 25(OH)D less than 30 ng/mL.

WHAT THEY DON'T SAY: They don’t say anything about the health risks of insufficient sun exposure.

WHAT 21ST CENTURY SCIENCE SAYS: The health risks of insufficient sun exposure are severe. Insufficient sun exposure has become the nation’s #2 public health problem, exceeded only by tobacco.

The Correct Science on Sun Exposure and Human Health

The purpose of the Sunshine Health Protection is to inform the public on the correct science of sun exposure and human health. We believe our website provides the most accurate, complete and current summary of the science on sun exposure and human health existing anywhere in the world. It is more accurate and complete than what you can learn from the World Health Organization, the CDC, the American Academy of Dermatology or any other medical association or governmental medical authority anywhere in the world, all of which appear to be stuck in the 20th century with outdated and incorrect 20th century groupthink science.

The human body is the most complex aggregation of molecules and atoms in the universe. Millions of chemical processes are occurring in our bodies each second giving us the means to breathe, eat, see, hear, taste, walk, think, replace worn-out parts, stop disease, circulate blood, and perform millions of other functions that keep us alive and in good health. Clean air and water, plenty of exercise and sleep, a healthy diet and good medical care are not enough to keep our awesome bodies running properly. We also need photons from the sun.

Here’s just a small look at the complexity of the human body.

There are 37 trillion cells in the human body, each of which performs a special function. Often thought of as the smallest unit of the body, each cell is actually made up of many even smaller parts including a complete string of your DNA and all of your 20,000 genes as well as chromosomes, proteins, carbohydrates and lipids, each of which also performs its own special function. Scientists estimate that the average cell contains 100 trillion atoms arranged into different molecules all interacting with each other.

With all this complexity, it is easy to imagine something going wrong. Malfunctions within cells, or failures of communication between cells, are not immediately noticeable by us, but sickness at the cellular level sooner or later manifests in higher risk of a wide variety of chronic and infectious diseases and other adverse health conditions including cancer, heart disease, stroke, Alzheimer’s, multiple sclerosis, rheumatoid arthritis, autism, schizophrenia, diabetes, obesity, asthma, preterm birth, maternal mortality, short-sightedness, COVID-19 and premature death.
And, if you are pregnant and have insufficient sun exposure, your baby is more likely to be born preterm, die from sudden infant death syndrome (SIDS), be autistic, get type 1 diabetes, have poor fetal brain development, have learning disabilities, have a low IQ, have poor language skills, have cavity-prone teeth, have high risk for schizophrenia, have asthma, have poor lung development, have high risk for lower respiratory tract infection (LRTI), have brittle bones and/or be constantly sick.

Scientists have known for more than a century that sun exposure produces vitamin D in our bodies and have suspected that vitamin D is not the only biomolecule produced by the sun. In the last 20 years, scientists have discovered several more have been discovered, the most important of which is nitric oxide. The 1998 Nobel Prize in Medicine was awarded to three scientists who discovered the importance of nitric oxide as a ubiquitous signaling molecule in the cardiovascular system that protects the heart, stimulates the brain and kills bacteria, but where the nitric oxide came from remained a mystery until the discovery in 2009 that ultraviolet radiation (UVR) converts cutaneous stores of photolabile nitric oxide derivates in the skin to nitric oxide which causes a pronounced decrease in blood pressure and other health benefits.

Other UVR-induced mediators include cytokines, corticotropin-releasing hormone, urocortins, proopiomelanocortin-peptides and enkephalins that are released into circulation to produce systemic effects independent of vitamin D synthesis. UVR has been shown to have a large effect on the skin transcriptome and there is evidence that UVR may also affect the blood transcriptome including genes for immunity.

Cell Malfunction

If you have less than a full tank of all the biomolecules produced by sun exposure, cells in your body will begin to malfunction and communications between cells will deteriorate. At first, these malfunctions and miscommunications may not manifest as any observable disease or adverse condition. But, unseen and undetected by you, they are gradually building up over time, and will eventually manifest as a serious disease or premature death.

Misdevelopment of Fetus

If you are pregnant and lack a full tank of these biomolecules during your pregnancy, your child may not develop properly in the womb.

Correct Science

Biomolecules

Metabolic Syndrome

Adolescents ages 12-19 with serum 25(OH)D in the lowest quartile (less than15 ng/mL) compared to the highest quartile (more than 26 ng/mL) have a 288% increased risk of metabolic syndrome. Reis et al., Pediatrics 2009; 124;e371-e379. Read the study here.

Persons aged 55 or older with serum 25(OH)D less than 20 ng/mL compared to more than 30 ng/mL have a 92% increased risk of metabolic syndrome. Vitezova et al., European Journal of Endocrinology 2015; 172:327-335. Read the study here.

Multiple Sclerosis

Insufficient sun exposure increases the risk of multiple sclerosis. Van der Mei et al., British Medical Journal 2003; 327:316-323. Read the study here.

Women with serum 25(OH)D less than 12 ng/mL compared to more than 20 ng/mL have a doubled increased risk of MS. Munger et al., Neurology 2017; 89:1578-1583. Read the study here.

Pregnant women with serum 25(OH)D less than 12 ng/mL compared to more than 12 ng/mL in early pregnancy have a 90% increased risk of having a child with MS. Munger et al., JAMA Neurology 2018; 73:515-519. Read the study here.

Muscular Weakness

Persons over age 60 years with serum 25(OH)D less than 12 ng/mL compared to more than 20 ng/mL have a 65% increased risk of muscle weakness. Aspell et al., Clinical Intervention in Aging 2019; 14:1751–1761. Read the study here.

Myopia (Short-Sightedness)

Insufficient sun exposure increases the risk of myopia (short-sightedness). French et al., Experimental Eye Research 2013; 114:58-68.

Obesity

Sun exposure reduces obesity independent of vitamin D but dependent on other sun-induced mediators such as nitric oxide. Geldenhuys et al., Diabetes 2014; 63:3759-3769. Read the study here.

Insufficient sun exposure of pregnant women increases the risk of childhood obesity. Daraki et al., Pediatric Obesity 2018; 13(8): 467-475. Read the study here.

Preeclampsia

Pregnant women with serum 25(OH)D less than 20 ng/mL compared to more than 20 ng/mL at 26 weeks gestation have a 67% higher risk of severe preeclampsia. Bodnar et al., Epidemiology 2014; 25:207-214. Read the study here.

Maternal preeclampsia is associated with higher blood pressure in offspring from early childhood through adolescence. Zhang et al., JAMA Network Open 2020; 3:e2019046. Read the study here.

Preterm Birth

Women with serum 25(OH)D less than 20 ng/mL compared to more than 40 ng/mL have a 133% increased risk of preterm birth. Wagner et al., Journal of Steroid Biochemistry & Molecular Biology 2016; 155:245-251. Read the study here.

Psoriasis

White-skinned persons with serum 25(OH)D less than 20 ng/mL compared to more than 20 ng/mL have a 150% increased risk of chronic plaque psoriasis. Gisondi et al., British Journal of Dermatology 2012; 166:505-510. Read the study here.

Rheumatoid Arthritis

Women in the lowest category of sun exposure compared with the highest category of sun exposure have a 37% increased risk of rheumatoid arthritis. Arkema et al., Annals of Rheumatic Diseases 2013; 72:506-511. Read the study here.

Rickets

In 1890, sun exposure was discovered to be a cure for rickets, a malformation of bones that crippled millions of children in the 19th century. Chesney RW, Nutrients 2012; 4:42-51. Read the study here.

Schizophrenia

Newborns with serum 25(OH)D less than 8 ng/mL compared to more than 14 ng/mL have a 44% increased risk of developing schizophrenia later in life. Eyles et al., Scientific Reports 2018; 8:17692. Read the study here.

Seasonal Affective Disorder (SAD)

The prevailing amount of sun exposure affects brain serotonergic activity, and thus underlies seasonal affective disorder (SAD). Lambert et al., The Lancet 2002; 360:1840-1842. Read the study here.

Sudden Infant Death Syndrome (SIDS)

75% of infants who die from SIDS have inadequate levels of 25(OH)D. Cohen et al., Pediatric and Development Pathology 2013; 16:292-300. Read the study here.

Sleep

Persons with serum 25(OH)D less than 20 ng/mL have a 50% increased risk of sleep disorders. Gao et al., Nutrients 2018; 10:1395.

Stroke

Persons with serum 25(OH)D in the lowest 4 percentiles compared to the highest 50 percentiles have an 82% increased risk of stroke. Brondum-Jacobsen et al., Annals of Neurology 2013; 73:38-47.

Tuberculosis

Persons with low serum 25(OH)D levels compared with high serum 25(OH)D levels have a 400% increased risk of tuberculosis. Talat et al., Emerging Infectious Diseases 2010; 16:853-855. Read the study here.

Urinary Tract Infections (UTI)

Premenopausal women with serum 25(OH) less than 15 ng/mL have a quadrupled risk of recurrent UTI. Nseir et al., International Journal of Infectious Diseases 2013; 17:e1121-e1124. Read the study here.

Children with serum 25(OH)D less than 15 ng/mL have a tripled risk of UTI. Tekin et al., Archives of Disease in Childhood 2014; 99(Suppl)A-201. Read the study here.

Number of Cells in Human Body

There are 37 trillion cells in the human body. Bianconi et al., Annals of Human Biology 2013; 40:463-471. Read the study here.

Optimum Level of Serum 25(OH)D

Most science today indicates that 30 ng/mL is sufficient. However, it is noted that the few humans today still living a pre-Industrial Age traditional pastoral lifestyle outdoors have 46 ng/mL. Luxwolda et al., British Journal of Nutrition 2012; 108:1557-1561. Read the study here.

Risks of Too Much Sun Exposure

In obtaining the sun exposure you need for good health, it is important to keep in mind the risks of sun exposure and take precautions to avoid or minimize them. The most important thing to remember is to avoid all sunburns.

The risks associated with sun exposure are skin cancer, eye damage and skin aging.

Skin Cancer. There are three types of skin cancer: melanoma, squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). Of the three, melanoma is by far the most serious.

Melanoma. The relationship between sun exposure and melanoma is unusual. Severe sunburns causing pain lasting 48 hours, blistering or peeling increase the risk of melanoma, but non-burning sun exposure even in very large amounts actually reduces the risk of melanoma.

A history of ever getting a severe sunburn compared to never getting a severe sunburn increases the risk of melanoma by 103% (Gandini et al., European Journal of Cancer 2005; 41:45-60). Read this study here.

Many severe sunburns compared to few severe sunburns increase the risk of melanoma by 83% (Caini et al., European Journal of Cancer 2009; 45:3054-3063). Read this study here. Five severe sunburns per decade of life compared to no severe sunburns increase the risk of melanoma by 224% (Dennis et al., Annals of Epidemiology 2008; 18:614-627). Read this study here.

Outdoor workers have lower risk of melanoma than indoor workers (Pukkala et al., Acta Oncologica 2009; 48:646-790). Read this study here. High occupational sun exposure compared to low reduces the risk of melanoma by 14% (Armstrong et al., Journal of Photochemistry and Photobiology 2001; 63:8-18). Read this study here. Non-burning sun exposure in childhood reduces the lifetime risk of melanoma (Kaskel et al., British Journal of Dermatology 2001; 145:602-609). Read this study here. The highest quartile of nonburning sun exposure compared to lowest quartile reduces the risk of melanoma by 22% (Vuong et al., International Journal of Cancer 2014; 134:2735-2741). Read this study here.

Consistent with these findings, the eminent melanoma cellular physicist/biologist Dr. F.R. de Gruijl of Leyden University in The Netherlands discovered in 2005 that melanocytes, unlike most other cells in the body, are not replicating cells, and severe sunburn or other trauma is required to stimulate their replication (van Schanke et al., Journal of Investigative Dermatology 2005; 124:241-24). Read this study here. It is only when cells divide and replicate that cancer can occur. Dr. A.C White of Cornell University confirmed Dr. de Gruijl’s discovery in 2017 (Moon et al., Cell Stem Cell 2017; 21:665-678). Read this study here.

It should be noted that some types of melanoma have nothing to do with sun exposure. These melanomas occur on the palms of the hands, the soles of the feet, or under the nails. The most common place is under the nail of the big toe. The famous musician Bob Marley died from melanoma under the nail of his big toe.

SCC. Severe sunburns also increase the risk of SCC. Six to ten severe sunburns in childhood increase the lifetime risk of SCC by 132% (de Vries et al., British Journal of Dermatology 2012; 167: Suppl 2:1-13). Read this study here. Severe sunburn at any age increases the risk of SCC by 23% (Armstrong et al., Journal of Photochemistry and Photobiology 2001; 63:8-18). Read this study here.

In contrast to melanoma, however, non-burning sun exposure can increase the risk of SCC. However, the amounts of sun exposure needed to increase the risk for SCC are very large: 20,000 hours for persons with light skins such as residents of The Netherlands and 70,000 hours for persons with darker skins such as residents of southern Europe (Kennedy et al, Journal of Investigative Dermatology 2003; 120:1087-1093). Read this study here. Since the vast majority of sun-related SCCs occur on the face and neck, persons who expect to have a large amount of sun exposure in their lifetimes can minimize any increased risk of SCC from getting the sun exposure they need for good health by covering their face and neck with a white towel or wearing a broad brimmed hat.

BCC. Severe sunburns also increase the risk of BCC. More than three lifetime severe sunburns compared to none increase the risk of BCC by 142% (Rosso et al., Tumori 1999; 85:435-442). Read this study here. Six to ten severe sunburns in childhood increase the lifetime risk of BCC by 133% (Rosso et al., British Journal of Cancer 1996; 73:1447-1454). Read this study here.

Severe sunburn at any age increases the risk of BCC by 40% (Armstrong et al., Journal of Photochemistry and Photobiology 2001; 63:818). Read this study here.

Like SCC, non-burning sun exposure in very large amounts can increase the risk of BCC: more than 20,000 lifetime hours for light-skinned persons (Kennedy et al, Journal of Investigative Dermatology 2003). Read this study here. More than 8,000 lifetime hours for darker-skinned persons with a decrease in risk at 200,000 lifetime hours (Rosso et al., British Journal of Cancer 1996; 73:1447-1454). Read this study here. Most BCCs also occur on the face and neck, so persons can protect themselves from BCC risk by covering their faces with a white towel when sunbathing.

Eye Damage. The principal risk of sun exposure regarding the eyes is cataracts (Lucas et al., Photochemical and Photobiological Sciences 2019; 18:641-680). Read this study here. This risk can be mitigated by wearing sunglasses or keeping your eyes closed when sunbathing.

Skin Aging. Skin aging risk from the sun occurs mostly on the face, so this risk can be mitigated by covering the face when sunbathing.

Use of Sunscreen

Most sunscreens on the market today will protect you from sunburns if they are used properly. The problem is that too few people use them properly. If you look on the back of a container of sunscreen, you will see in small print the instructions to “apply liberally”, reapply within 80 minutes of swimming or sweating, reapply after toweling off and in any case reapply every 2 hours. What does “apply liberally” mean? Scientifically, it means apply it with a thickness of 2.0 milligrams per square centimeter.. How many people can figure that out when applying sunscreen at the beach? And how many people forget to reapply it (also “liberally”) every two hours when they’re having fun, taking a nap or having a few beers?

The answer is very few people. That’s why scientific studies show that sunscreen is not very helpful in preventing sunburn or in reducing the risk of melanoma. In fact, a recent study of sunburns by the CDC and the National Cancer Institute of the National Institutes of Health found that 68% of persons reporting sunburn were using sunscreen at the time of their sunburn. Public health authorities and the medical establishment in general tend to ignore these studies and fail to warn the public about the ineffectiveness of sunscreen as it is actually being used. They also continue to insist that a tan does very little if anything to protect you from sunburn, having at most an SPF of 2-3. The only actual experiment ever done in history to determine the SPF of a tan was done by our Foundation in 2021. It found that the SPF of a tan is 24, and of course a tan doesn’t wash off or have to be reapplied every 2 hours or even weekly. Click here for a report of that experiment.

Scientific Studies on Health Risks of Insufficient Sun Exposure

The following is a listing of the diseases that scientists have discovered are associated with insufficient sun exposure, together with citations to the peer-reviewed scientific journals in which these discoveries were published. If you have insufficient sun exposure, you are at high risk for getting one or more of these diseases. Which one(s) you get is dependent on your personal makeup and the extent of your sun exposure insufficiency.

Note: 70-90% of the biomolecule 25(OH)D is produced in the body by sun exposure (Adams et al., New England Journal of Medicine 1982; 306:722-725; Macdonald et al., Osteroporos International 2011; 22:2461-2472; Holick MF. McCollum award lecture 1994: vitamin D— new horizons for the 21st century. American Journal of Clinical Nutrition 1994 ; 60:619–630; https://www.healthywa.wa.gov.au/Articles/U_Z/Vitamin-D) so the blood level of 25(OH)D is at the same time the best metric for vitamin D status and the best metric for sun exposure. This level is easily determined by a standard vitamin D blood test.

All-Cause Mortality

12.8% of all deaths in the United States (340,000 deaths annually) are attributable to serum 25(OH)D of less than 30 ng/mL.
Chowdhury et al., British Medical Journal 2014; 348:g1903. Read the study here.

Sun avoidance is a risk factor for death of similar magnitude to smoking.

Lindqvist et al., Journal of Internal Medicine 2016; 280:375–387. Read the study here.

Anti-Microbial Peptides

Insufficient sun exposure of pregnant women increases the risk of insufficient production of anti-microbial peptides in infants.

Balan et al., Handbook of Vitamin D in Human Health: Prevention, treatment and toxicity. Human Health Handbooks no. 4 (2013). Read the study here.

Atrial Fibrillation (AFIB)

Persons with serum 25(OH)D less than 20 ng/mL have a 23% increased risk of AFIB. Liu et al., Nutrition Journal 2019; 18:73-83.

Read the study here.

Alzheimer’s Disease

Insufficient sun exposure increases the risk of Alzheimer’s disease by 122%. Littlejohns et al., Neurology 2014; 83:920-928. Read the study here.

Persons over 65 years old with serum 25(OH)D less than 10 ng/mL have a nearly three-fold increased risk of Alzheimer’s disease. Feart et al., Alzheimer’s & Dementia 2017; 13:1207-1216. Read the study here.

Arthritis

Women with low sun exposure vs. high sun exposure have a 27% increased risk of rheumatoid arthritis. Arkema et al., Annals of Rheumatic Diseases 2013; 72:506-511. Read the study here.

Children with serum 25(OH)D less than 30 ng/mL are at increased risk of juvenile idiopathic arthritis. Finch et al., Pediatric Rheumatology 2018; 16:34-51. Read the study here.

ARTI

Persons with serum 25(OH)D less than 10 ng/mL vs. more than 30 ng/mL have a 83% increased risk of incidence of acute respiratory tract infection (ARTI) from cold and flu viruses and a 146% increased risk of severity of ARTI (including mortality) from cold and flu viruses. Pham et al., International Journal of Environmental Research and Public Health 2019; 16:3020-3035. Read the study here.

ARTI from the COVID-19 virus is the primary cause of the severity of, and death from, COVID-19. Vitamin D supplementation does not reduce the risk of ARTI. Pham et al., Lancet Diabetes Endocrinology 2021; 9. Read the study here.

Asthma

Low maternal serum 25(OH)D triples the risk that male children will have asthma at age 6 and increases the lifetime risk that male and female offspring will develop lung disease. Zosky et al., Annals of the American Thoracic Society 2014; 11:571-577. Read the study here.

Insufficient sun exposure in early childhood is associated with increased risk for persistent asthma. Hollams et al., The Journal of Allergy and Clinical Immunology 2017; 139:472-481. Read the study here.

Athletic Performance

Insufficient sun exposure adversely affects athletic performance. Cannell et al., Medicine & Science in Sports & Exercise 2009; 41:1102-1110. Read the study here.

High serum 25(OH)D increases strength, jump height, jump velocity, exercise capacity and physical performance and reduces inflammation and pain. Shuler et al., Sports Health 2012; 4:496-501. Read the study here.

Autism

Maternal serum 25(OH)D concentrations at midgestation of less than 10 ng/mL compared to more than 20 ng/mL are correlated with a 142% increased risk of autism in the child. Vinkhuyzen et al., British Journal of Psychiatry Open 2017: 3:85-90. Read the study here.

Bone Health

It has been well established for decades that low levels of serum 25(OH)D are associated with poor bone health. Holick MF. Vitamin D: Physiology,Molecular Biology and Clinical Applications. Second Edition Humana Press 2010. Read the study here.

Brain Development of Fetus

Insufficient sun exposure of pregnant women adversely affects brain development of fetus and is associated with poor mental development to the extent that the chances of the infant developing an IQ over 110 are decreased by 50%. Morales et al., Pediatrics 2012; 130:e913-e920. Read the study here.

Cancer (Bladder)

Persons with serum 25(OH)D less than 10 ng/mL compared to more than 30 ng/mL have a 83% increased risk of bladder cancer. Amaral et al., Journal of the National Cancer Institute 2012; 104:1897-1904. Read the study here.

Persons with serum 25(OH)D less than 30 ng/mL vs. more than 30 ng/mL have a 54% increased risk of bladder cancer. Zhao et al., Nutrition 2016; 32:515-23. Read the study here.

Cancer (Breast)

Persons with breast cancer and with the lowest quintile of serum 25(OH)D (generally, 20 ng/mL) compared to the highest quintile (generally, 30 ng/mL) have a 376% increased risk of death from breast cancer. Mohr et al., Anticancer Research 2014; 34:1163–1166. Read the study here.

Persons with serum 2(OH)D less than 20 ng/mL compared to more than 60 ng/mL have a 400% increased risk of breast cancer. McDonnell et al., PLoS ONE 2018; 13;e0199265-276. Read the study here.

Cancer (Colon)

Persons with serum 25(OH)D in the lowest quintile (median 6 ng/mL) compared to the highest quintile (median 37 ng/mL) have a 104% increased risk of colorectal cancer. Gorham et al., American Journal of Preventative Medicine 2007; 32:210-216. Read the study here.

Cancer (Endometrial)

Swedish women who never sunbathe in the summer compared to Swedish women who commonly sunbathe in the summer have a 25% increased risk of endometrial cancer. Epstein et al., British Journal of Cancer 2009; 101:537-540. Read the study here.

Cancer (Lymphoma)

Persons with serum 25(OH)D less than 30ng/mL compared with more than 30 ng/mL have a 82% increased risk of dying from Hodgkin’s lymphoma. Borchmann et al., Journal of Clinical Oncology 2019; 37:3528-3537. Read the study here.

Cancer (Melanoma)

White persons with serum 25(OH)D less than 20ng/mL compared with more than 30 ng/mL have an eight-fold increased risk of melanoma. Lombardo et al., Scientific Reports 2021; 11:5815-5824. Read the study here.

A previous study found that white persons with serum 25(OH)D more than 30 ng/mL compared to less than 20 ng/mL had a 96% reduced risk of melanoma. Cattaruzza et al., European Journal of Cancer Prevention 2019; 28:203-211. Read the study here.

Cancer (Non-Hodgkin's Lymphoma)

Persons in the highest quartile of sun exposure compared to persons in the lowest quartile have a 61% increased risk of diffuse large B-cell lymphoma (the most common type of non-Hodgkin’s lymphoma). Boffetta et al., International Journal of Epidemiology 2008; 37:1080-1094. Read the study here.

Cancer (Ovarian)

Women of European ancestry have a 54% increased risk of ovarian cancer for each 13 ng/mL decrease in serum 25(OH)D below 30 ng/mL (83% increased risk for 20 ng/mL compared to 30 ng/mL). Ong et al., International Journal of Epidemiology 2016; 45:1619-1630.

Cancer (Pancreatic)

Countries with the lowest solar irradiance have 5 times the incidence of pancreatic cancer as countries with the highest solar irradiance. Garland et al., Journal of Steroid Biochemistry & Molecular Biology 2015 (published online April 30, 2015). Read the study here.

Cancer (Prostate)

Men of European ancestry with serum 25(OH)D less than 12 ng/mL have a 266% increased risk of a high Gleason Score (greater than 4+4), and men of African ancestry with serum 25(OH)D less than 12 ng/mL have a 389% increased risk of a high Gleason Score (greater than 4+4). Murphy et al., Clinical Cancer Research 2014; 20:2289-2299.

Cancer (Stomach)

Persons with serum 25(OH)D less than 20 ng/mL have an increased risk of stomach cancer. Vyas et al., World Journal of Gastrointestinal Oncology 2016; 15:688-694. Read the study here.

Circadian Rhythm

Sun exposure reinforces circadian rhythm, and prevents rhythm disturbances which adversely affect key aspects of cell growth, DNA damage responses and metabolism. Van der Rhee et al., Cancer Research Frontiers 2016; 2:156-183. Read the study here.

COVID-19

Persons with serum 25(OH)D less than 20 ng/mL have a 77% increased risk of testing positive for COVID-19. Meltzer et al., Journal of the American Medical Association Network Open 2020; 3:e2019722-e2019734. Read the study here.

Sun exposure produces vitamin D related lumisterol hydroxymetabolites in the human body which inhibit the viral replication machinery of COVID-19, confirming prior studies showing that sun exposure protects against COVID-19. Qayyum et al., American Journal of Physiology-Endocrinology and Metabolism 2021; 321:e246-e251. Read the study here.

Persons with serum 25(OH)D less than 20 ng/mL have a 138% increased risk of hospitalization from COVID-19 and a 84% increased risk of death from COVID-19. Chiodini et al., Frontiers in Public Health 2021; 9:736665. Read the study here.

CVD

Sun exposure mobilizes nitric oxide in the skin and delivers it to the bloodstream to exert coronary vasodilator and cardioprotective as well as hypertensive effects. Feelisch et al., European Heart Journal 2010; 31:1041-1045. Read the study here.

Children ages 3-8 with serum 25(OH)D in the lowest quartile (less than 16 ng/mL) have a 70% increased risk of dangerously high thickness of the posterior wall of their left carotid artery as adults, which is an accurate predictor of adverse cardiovascular events. Juonala et al., Journal of Clinical Endocrinology and Metabolism 2015; 100. Read the study here.

Persons with serum 25(OH)D less than 30 ng/mL have increased risk of congestive heart failure, impaired systolic and diastolic function, myocardial infarction, peripheral vascular disease abdominal aortic aneurysm, AFIB and hypertension. Kheiri et al., Clinical Hypertension 2018; 24:9-18. Read the study here.

Dental Cavities in Infants

Low sun exposure of women during pregnancy is associated with increased risk of dental caries among offspring in the first year of life. Schroth et al., Pediatrics 2014; 133:e1277-e1284.

Depression

Persons with serum 25(OH)D less than 15 ng/mL compared to more than 25 ng/mL have a 121% increased risk of depression. Anglin et al., The British Journal of Psychiatry 2013; 202:100-107. Read the study here.

Diabetes Type 1

Persons with serum 25(OH)D less than 17 ng/mL compared to more than 40 ng/mL have a 250% increased risk of type 1 diabetes. Gorham et al., Diabetologia2012; 55:3224-3227. Read the study here.

Less sun exposure (below the median) compared to more sun exposure (above the median) for women during pregnancy is associated with a 67% increased risk of type 1 diabetes in their male children at ages five to nine years. Jacobsen et al., Journal of Pediatric Endocrinology and Metabolism 2016; 29:417–424. Read the study here.

Diabetes Type 2

Persons with serum 25(OH)D less than 5 ng/mL compared with more than 20 ng/mL have a 50% increased risk of type 2 diabetes. Afzal et al., Journal of Clinical Chemistry and Laboratory Medicine 2013; 59:381–391. Read the study here.

Women without active sun exposure habits compared with women with active sun exposure habits have a 43% increased risk of type 2 diabetes. Lindqvist et al., Diabetes Research and Clinical Practice 2010; 90:109-114. Read the study here.

Eczema

Greater UV exposure in early infancy is associated with lower incidence of eczema by 6 months of age. Vitamin D supplements have no effect. Rueter et al., Journal of Allergy and Clinical Immunology 2019; 143:1012-1020. Read the study here.

Erectile Dysfunction

Men with serum 25(OH)D less than 20 ng/mL compared to more than 30 ng/mL have a 30% increased risk of erectile dysfunction. Farag et al., Atherosclerosis 2016; 252:61-67. Read the study here.

Flu and Colds

Persons with serum 25(OH)D less than 10 ng/mL compared to more than 30 ng/mL have an 84% increased risk of upper respiratory tract infections. Ginde et al., Archives of Internal Medicine 2009; 169:384-390. Read the study here.

Persons with serum 25(OH)D less than 10 ng/mL compared to more than 30 ng/mL have an 83% increased risk of acute respiratory tract infection (ARTI) from flu and colds and a 146% increased risk of severity of ARTI. Pham et al., International Journal of Environmental Research and Public Health 2019; 16:3020-3035. Read the study here.

Hypertension

Sun exposure produces nitric oxide in the skin which gets in the blood stream and reduces blood pressure independent of vitamin D. Oplander et al., Circulation Research 2009; 105:1031-1040. Read the study here.

Adolescents ages 12-19 with serum 25(OH)D in the lowest quartile (less than 15 ng/mL) compared to the highest quartile (more than 26 ng/mL) have a 136% increased risk of hypertension. Reis et al., Pediatrics 2009; 124:e371-e379. Read the study here.

UVA irradiation of human skin vasodilates arterial vasculature and lowers blood pressure. Liu et al., Journal of Investigative Dermatology 2014; 134:1839-1846. Read the study here.

Children with serum 25(OH)D less than 11 ng/mL at birth and less than 25 ng/mL in early childhood have a 104% increased risk of high blood pressure at ages 3 to 18 years, and high blood pressure at these ages in an important determinant of subsequent hypertension and cardiovascular disease later in life. Wang et al., Hypertension 2019; 74:421–430. Read the study here.

Immune System

Sunlight, through a mechanism separate from vitamin D, energizes T cells that play a central role in immunity. Phan et al., Scientific Reports 2016; 6:39479-39490. Read the study here. Hart et al., Nature Reviews Immunology 2011; 1:584-596. Read the study here.

Inflammatory Bowel Disease and Gut Biome

Scientists recently discovered that sun exposure diversifies and enriches disease and gut biomebacteria in the gut with implications for the role of insufficient sun exposure in inflammatory bowel diseases (Crohn’s disease and ulcerative colitis). Bosman et al., Frontiers in Microbiology 2019; 10:2410-2421. Read the study here. Fletcher et al., Nutrients 2019; 11:1019-1935. Read the study here.

Language Difficulties in Infants

Pregnant women with serum 25(OH)D less than 18 ng/mL compared to more than 28 ng/mL had twice the risk of having a child that experienced significant language difficulties. Whitehouse et al., Pediatrics 2012; 129:485-493. Read the study here.

Learning Difficulties

Pregnant women with the lowest quintile of sun exposure during pregnancy compared to the highest quintile have a 82% increased risk of having a child that experiences learning disabilities. Sun exposure in the first trimester is essential for fetal brain development. Hastie et al., Scientific Reports 2019; 9:9356. Read the study here.

Lower Respiratory Tract Infection (LRTI) in Infants

Infants born with serum 25(OH)D less than 20 ng/mL compared to more than 30 ng/mL have a 500% increased risk of severe lower respiratory tract infection (LRTI) in the first year of life. Belderbos et al., Pediatrics 2011; 127:e1513-e1520. Read the study here.

Lung Development in Infants

Insufficient sun exposure of pregnant women increases the likelihood of poor lung development in infants. Balan et al., Handbook of Vitamin D in Human Health: Prevention, treatment and toxicity. Human Health Handbooks no. 4 (2013).

Macular Degeneration (Age-Related) (AMD)

Women with a genetic risk for AMD who have serum 25(OH)D less than 12 ng/mL have a 570% increased risk of AMD compared to women with a genetic risk for AMC who have serum 25(OH)D more than 20 ng/mL. Millen et al., JAMA Opthalmology 2015; 133:1171-1179. Read the study here.

Studies A - L

Studis M - Z

Risks

Suncreen

Sun Exposure Should Never Involve Sunburn.

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America's second largest public health problem is insufficient sun exposure. It's responsible for 340,000 preventable deaths per year, just behind tobacco and ahead of obesity.

The public needs to be aware of insufficient sun exposure risks and increase daily sun exposure to improve health.