Basic Health Habit No.8: Sunlight

UVB, UVA, and Melanoma

Exposure to sunlight causes vitamin D to be produced in your skin. But only a portion of the solar spectrum, known as ultraviolet B (UVB), has this effect. Ultraviolet B rays are strongest at noon.

Sunshine is a basic health habit. Exposure to sunlight is the best source of vitamin D. However, due to increased UVR levels, this is the one basic health habit that requires careful moderation individually.

Other parts of the solar spectrum can have very different and even harmful effects. UVA can cause cancerous mutations, and can also break down the vitamin D formed in your skin after outdoor UVB exposure.

Vitamin D is a potent defense against melanoma. Melanoma cells convert it to calcitriol, which causes tumour growth inhibition and apoptotic cell death in vitro and in vivo.

New research shows that increased UVA exposures and inadequately maintained cutaneous levels of vitamin D, promote melanoma.

cover up

Sun Protection Behaviour (SPB)
To reduce your ultra violet radiation (UVR) 
exposure risks
    • There are natural ways to protect yourself from sunburn that you can use instead of toxic sunscreens. Two non-toxic ingredients that scatter both UVB and the more damaging UVA rays are the natural minerals titanium dioxide and zinc oxide.
    • The most obvious and safest option is to put on a long sleeved shirt, pants and a hat once you’ve reached your limit of sun exposure: 15 minutes maximum for fair-skinned individuals who burn and peel. 
    • UVR exposure risks can be influenced by: poor health, melanin content of skin, skin health, UVR over-exposure, geography, seasons, sun elevation, latitude, cloud cover, altitude, ozone, ground (or water) reflection, neglect of basic health habits, cutaneous levels of vitamin D, unhealthy aging, health complications, illness, medications, and surgery.
    • Know your limit. Cover up and wear a hat. UVR exposure still happens in the shade.

    As sunlight passes through the atmosphere, all UVC and approximately 90% of UVB radiation are absorbed by ozone, water vapour, oxygen and carbon dioxide. UVA radiation is less affected by the atmosphere. Therefore, the UV radiation reaching the Earth’s surface is largely composed of UVA with a small UVB component.

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    The Circadian Control of Skin and Cutaneous Photodamage

    Biologically, light, including ultraviolet (UVR) radiation, is vital for life. Natural protection against UVR damage has been affected by lifestyle changes over the past century, including changes in our sun exposure due to working environments, and the use of sunscreens. 

    In addition, extended day time through the use of artificial light contributes to the disruption of our circadian rhythms; the daily cycles of changes in critical bio-factors, including gene expression. Circadian disruption has been implicated in many health conditions, including cardiovascular, metabolic, and psychiatric diseases, as well as many cancers. The pineal hormone, melatonin, plays a role in both circadian regulation, as well as protection from UVR skin damage.

    UV light in the eye activates a chemical known as the melanocyte-stimulating hormone which makes the skin thicken and go brown to protect it from harmful ultra violet radiation rays. 

    Light in the eye is an important factor. It helps to short-circuit the body's natural defence mechanism against the sun. Sunglasses reduce the amount of ultra-violet light reaching key areas of the eye, tricking the brain into believing less harmful rays have penetrated the body.

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    Human skin is repeatedly exposed to various DNA-damaging environmental influences and therefore requires numerous endogenous (internal, physiological) mechanisms to protect against, reduce, and to repair damage. Human skin has developed many defence mechanisms to guard against environmental stress and the damaging effects of UVR: epidermal thickening; the stimulation of melanin synthesis; the synthesis of vitamin D3; DNA repair mechanisms and apoptosis, and antioxidant enzymes.

    Skin pigmentation is the most important photo protective factor, since melanin, besides functioning as a broadband UVR absorbent, has antioxidant and oxygen-free radical scavenging properties. Many epidemiological studies have shown a lower incidence for skin cancer in individuals with darker skin compared to those with fair skin. Melanin absorbs 50-75% of ultra violet radiation (UVR).

    Skin pigmentation influences the effectiveness of vitamin D3 synthesis in the skin as melanin competes and absorbs UVB photons needed for D3 synthesis.

    Hormonal Regulation of Pigmentation
    Tanning is determined directly by the response of melanocytes to UVR, but is also affected indirectly by a complex system of paracrine and autocrine factors such as hormones, cytokines, and growth factors, whose synthesis in epidermal cells is influenced by UVR.

    What Is Vitamin D? 

    Vitamin D (calciferol), is a fat-soluble vitamin. It is found in food, but it can also be made in your body after exposure to ultraviolet rays from the sun. Vitamin D exists in several forms, each with a different activity. Some forms are relatively inactive in the body, and have limited ability to function as a vitamin. The liver and kidney help convert vitamin D to its active hormone form.

    Vitamin D plays a crucial role in the absorption and maintenance of calcium for bone health, nerve and muscle function, and blood coagulation. The major biologic function of Vitamin D is to maintain normal blood levels of calcium and phosphorus. It promotes bone mineralization in concert with a number of other vitamins, minerals, and hormones. 

    The active form of vitamin D also acts as an effective regulator of cell growth and differentiation in a number of different cell types, including cancer cells. 

    Vitamin D deficiency has been associated with insulin deficiency and insulin resistance.

    Vitamin D Co-factors:
    How well vitamin D works depends on the amount of other vitamins and minerals that are present in your body. The other vitamins and minerals needed to help vitamin D work well are called cofactors. 

    To get the most benefit from vitamin D, you must have other cofactors in your body. The ones listed below are the most important.
    • Magnesium
    • Vitamin K
    • Zinc
    • Boron
    • Vitamin A
    Vitamin D Council

            Vitamin D Deficiency has been associated with:
            • Melanoma 
            • Adrenal insufficiency 
            • Alzheimer's 
            • Allergies 
            • Autoimmune disorders including Multiple Sclerosis and Rheumatoid Arthritis 
            • Cancers of the colon, breast, skin, and prostate 
            • Depression, Seasonal Affective Disorder (SAD)Diabetes, Type 1 and 2 
            • Gluten intolerance, lectin intolerance 
            • Heart disease, Hypertension 
            • Syndrome X 
            • Infertility, sexual dysfunction 
            • Learning and behavior disorders 
            • Misaligned teeth and cavities 
            • Myopia (nearsighted) 
            • Obesity 
            • Osteopenia (low bone mineral density), osteoporosis, rickets, osteomalacia (adult rickets) 
            • Parkinson's 
            • PMS 
            • Psoriasis 
            • Use of corticosteroids 

            Vitamin D is not a vitamin. It is more appropriately classified as a pro-hormone. Not only is it a pro-hormone, it is a sunlight derived pro-hormone. The active hormone D, calcitriol, controls calcium in vertebrates. Calcium controls innumerable processes in the human body, including specific responses in muscles, bones and glands. Calcitriol is a major player in genomic actions determining how our cells express themselves and regulating production of numerous substances including enzymes, hormones and neurotransmitters.

            Just one example of an important gene that vitamin D up-regulates is your ability to fight infections. It produces over 200 anti-microbial peptides, the most important of which is cathelicidin, a naturally occurring broad-spectrum antibiotic. Vitamin D can decrease your risk for common respiratory infections as well. At least five studies show an inverse association between lower respiratory tract infections and D levels. That is, the higher your vitamin D level, the lower your risk of contracting colds, flu, and other respiratory tract infections. A 2007 study suggests higher vitamin D status enhances your immunity to microbial infections.

            Vitamin D is an essential part of the endocrine system. It controls several adrenal hormones, the growth of cells, the production of enzymes.

            Hormones have DNA receptor sites, while Vitamin D is a part of non-genomic coenzyme systems. Vitamins A and D are both vitamins and hormones. Vitamin D is also produced in plants such as algae, as well as mushrooms (which are neither animals nor plants) exposed to ultraviolet-B (UVB) radiation.

            Serum 25(OH)D levels should be in the 30 to 40 ng/ml (75-100 nmol/L) range for cancer prevention and optimal health. The only way to determine 25(OH)D levels is with a blood test which can be ordered through a physician or nutritionist. However, care
            should be exercised in the choice of a laboratory because the testing methods and quality of the tests may vary. In addition, since 25(OH)D and parathyroid hormone (PTH) are inversely correlated and have opposite effects on calcium in bones, it would also be useful to have PTH levels measured.


            Exposure to sunlight is the best source of vitamin D. Ultraviolet (UVB) rays from sunlight trigger vitamin D synthesis in the skin. 15 to 30 minutes per day generally applies to fair-skinned, thin, younger individuals, with the more of the body exposed, the better. Darker-skinned individuals may require several hours per day.

            Melanoma rates in North America are rising as a result of unhealthy UVR exposure, neglected basic health habits, and decreased cutaneous levels of vitamin D. When you stay out of the sun entirely, you effectively avoid the system nature created to help prevent skin cancer naturally, because the key to unlocking this mechanism is vitamin D.

            Vitamin D goes directly to the genes in your skin where it helps prevent the types of abnormalities that ultraviolet A light causes. When you avoid the sun entirely, or envelope on sun block whenever you go out, your skin is not making any vitamin D, and you’re left without this built-in cancer protection.

            Dietary sources of vitamin D are generally insufficient to produce optimal serum 25-hydroxyvitamin D 25(OH)D since milk contains only 400 I.U. of vitamin D3 and 800 to 1000 I.U. per day are probably required. Fish oil with vitamin D can be consumed, but one should see whether and how much vitamin A is included. Vitamins A and D interact and you need the proper balance of vitamin A. Vitamin D is stored in blood for a few weeks and in fat for a few months. Some of the best food sources are mushrooms, liver, egg yolks, and fish.

            Sun exposure benefits your health by stimulating your skin to produce vitamin D. Vitamin D is a hormone-like substance critical for the vast majority of your biological functions, including:

            • Cardiovascular health 
            • Cognition 
            • Sleep 
            • Immunity 
            • Metabolism 
            • Bone health and strength 
            • Digestion 
            • Protection from melanoma and other cancers 

            Every cell and tissue in your body needs vitamin D to function properly. But it does more than just that. Vitamin D is different from other vitamins in that it influences your entire body. Receptors that respond to the vitamin have been found in almost every type of human cell, from your brain to your bones. This is why researchers are finding health benefits from vitamin D in virtually every area they look. For example, optimizing your vitamin D levels can help you to prevent as many as 16 different types of cancer including pancreatic, lung, breast, ovarian, prostate, and colon cancers. 

            When you get your vitamin D from appropriate sun exposure, your body can self-regulate and reduce vitamin D production if you don't need it, which makes it very difficult to overdose on vitamin D from sun exposure.

            D2 and D3

            Supplemental vitamin D comes in two forms: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Recent studies have shown that vitamin D3 is a more potent form of vitamin D. Vitamin D2 has a shorter shelf life, and its metabolites bind with protein poorly, making it less effective.

            One unit of cod liver oil (containing vitamin D3) has been shown to be as effective as four units of Viosterol (a medicinal preparation of vitamin D2).

            Basically there are two types of oral vitamin D supplements. The natural ones are D3, and they contain the same vitamin D your body makes when exposed to sunshine. The synthetic ones are vitamin D2, which are sometimes called ergocalciferol.

            Once either form of the vitamin is in your body, it needs to be converted to a more active form. Vitamin D3 is converted 500 percent faster than vitamin D2. Interestingly, it was previously thought that the kidney exclusively performed this function, However, in 1998 Dr. Michael Hollick, the person who discovered activated vitamin D, showed that many other cells in your body can make this conversion, but they use it themselves, and it is only the kidney that makes enough to distribute to the rest of your body.

            However, nearly all the prescription-based supplements contain synthetic vitamin D2, which was first produced in the 1920s through ultraviolet exposure of foods. The process was patented and licensed to drug companies for use in prescription vitamins. The vitamin D that is added to milk is not D3 but the inferior vitamin D2.

            Vitamin D Toxicity

            When you take large amounts of vitamin D, your liver produces too much of a chemical called 25(OH)D.

            When your 25(OH)D levels are too high, this can cause high levels of calcium to develop in your blood. High blood calcium is a condition called hypercalcemia. Hypercalcemia can affect iron absorption.

            The symptoms of hypercalcemia include:
            • feeling sick or being sick
            • poor appetite or loss of appetite
            • feeling very thirsty
            • passing urine often
            • constipation or diarrhea
            • abdominal pain
            • muscle weakness or pain
            • feeling confused
            • feeling tired

            In some rare diseases, you may be at risk of hypercalcemia even if you have low vitamin D levels and haven’t taken much vitamin D. These diseases include primary hyperparathyroidism, sarcoidosis and a few other rare diseases.


            Sunblocks are formulated to shield against UVB rays, while sunscreens protect against UVA. Broad-spectrum protection formulated sunscreen protects against both UVA and UVB rays.

            Sunblocks and broad-spectrum sunscreen formulations block your body’s production of vitamin D  by as much as 97.5 to 99.9 percent. 

            Prevent Skin Damage
            Ultraviolet light from the sun comes in two main wavelengths: UVA and UVB. UVB helps your skin produce vitamin D. UVA penetrates your skin more deeply and causes more free radical damage. UVA rays are constant during ALL hours of daylight, throughout the entire year, unlike UVB, which are low in morning and evening, and high at midday. 

            Two non-toxic ingredients that scatter both UVB and the more damaging UVA rays are the natural minerals titanium dioxide and zinc oxide. 

            What Makes Sunscreens Toxic? 

            A study in the April 2004 Journal of Chromatography found that there was significant penetration into the skin of all sunscreen agents they studied and it goes straight into your blood stream. Scientists are not even sure whether sunscreen prevents against melanoma. They’ve suggested that sunscreen may prevent sunburn, but may fail to actually protect against cancer because most sunscreens only screen out UVB, which makes vitamin D, not the UVA that causes most of the damage. Some studies have even found a link between melanoma and the use of commercial sunscreen.

            Vitamin A Toxicity
            Retinal palmitate and retinoic acid, two forms of vitamin A, may speed the development of skin tumors and lesions when applied to the skin in the presence of sunlight. Too much pre-formed vitamin A in skin creams and make up, including retinol, retinyl palmitate, retinyl acetate, and retinyl linoleate, can cause a variety of health problems, including liver damage, brittle nails, hair loss, osteoporosis and hip fractures in older adults. EWG recommends that consumers avoid sunscreens and other skin and lip products containing vitamin A, retinyl palmitate, retinol, retinyl acetate, retinyl linoleate, and retinoic acid.

            Cream vs Spray-on or Powder Sunscreens
            Choose a cream, not a spray or powder sunscreen. Mineral-based sunscreens contain nanoparticles. Research shows that titanium dioxide and zinc oxide do not migrate through skin, but inhaled nanoparticles enter the blood stream through the lungs. Further research is needed into the impact of these particles on the environment and into the safety of skin application. In the meantime, choose mineral-based creams. While you might like transparent options, larger white particles provide better UVA protection.

            As you can see from the list below, compiled from the Environmental Working Group: Skin Deep Website, there are lots of potential dangers lurking in your sunscreens: 

            Octinoxate (Octyl Methoxycinnamate) The most widely used sunscreen ingredient, known for its low potential to sensitize skin or act as a photo-allergen. Estrogenic effects are noted in laboratory animals as well as disruption of thyroid hormone and brain signaling. Has been found to kill mouse cells even at low doses when exposed to sunlight! 

            Oxybenzone (Benzophenone-3) Associated with photo-allergic reactions. This chemical absorbs through your skin in significant amounts. It contaminates the bodies of 97% of Americans according to Centers for Disease Control research. Health concerns include hormone disruption and cancer.

            Octisalate is a weak UVB absorber with a generally good safety profile among sunscreen ingredients. It is a penetration enhancer, which may increase the amount of other ingredients passing through skin. 

            Avobenzone (Parsol 1789) Primarily a UVA-absorbing agent, sunlight causes this unstable ingredient to break down into unknown chemicals, especially in the presence of another active, Octinoxate. 

            Octocrylene Produces oxygen radicals when exposed to UV light. 

            Homosalate Research indicates it is a weak hormone disruptor, forms toxic metabolites, and can enhance the penetration of a toxic herbicide. 

            Micronized Titanium Dioxide Sunscreens with micronized titanium dioxide may contain nanoparticles. Micronized TiO2 offers greater sun protection than conventional (larger) particles. These small particles do not penetrate skin but may be more toxic to living cells and the environment. Inhalation of powders and sprays is a concern. 

            Micronized Zinc Oxide See Micronized Titanium Dioxide above. 

            Titanium Dioxide Appears safe for use on skin, due to low penetration but inhalation is a concern. 

            Ensulizole (Phenylbenzimidazole Sulfonic Acid) Known to produce free radicals when exposed to sunlight, leading to damage of DNA, this UVB protector may have the potential to cause cancer. 

            Nano Zinc Oxide offers greater sun protection than larger zinc particles. Comparatively little is known regarding potential health effects of nanoparticles. They do not penetrate healthy skin, and thus appear to pose a low health risk in lotions. Inhalation of powders and sprays is a concern. 

            Nano Titanium Dioxide Same as Nano Zinc Oxide, above.

            Zinc Oxide has a long history of use in sunscreen and other skin care products; little absorption and no adverse health effects are reported. 

            Padimate O (Octyl Dimethyl PABA / PABA Ester) A derivative of the once-popular PABA sunscreen ingredient, research shows this chemical releases free radicals, damages DNA, has estrogenic activity, and causes allergic reactions in some people. 

            Menthyl Anthranilate One study found that it produces damaging reactive oxygen species when exposed to sunlight. 

            Mexoryl SX 2 hours of sunlight can degrade as much as 40% of this active ingredient. Low skin penetration. 

            Methylene Bis-Benzotriazolyl Tetramethylbutylphenol 
            Not an approved active ingredient in the U.S. Few studies exist on this chemical. It is photostable and does not absorb through your skin. 

            Sulisobenzone (Benzophenone-4) Can cause skin and eye irritation. Does not penetrate your skin to a large degree, but enhances the ability of other chemicals to penetrate. 

            Benzophenone-2 Not approved for use in North American sunscreens. Concerns about hormone disruption.

            Natural, Healthy Sources of SPF

            Moroccan Argan Nuts

            Argan Oil SPF: 47
            Carrot Seed Oil: SPF 38-40
            Raspberry Seed Oil: SPF 28-50
            Wheatgerm Oil: SPF 20
            Avocado Oil: SPF 4-15
            Hemp Seed Oil: SPF 6
            Macadamia Nut Oil: SPF 6
            Almond Oil: SPF 5
            Coconut Oil: SPF 2-8
            Olive Oil: SPF 2-8
            Shea Butter: SPF 3-6
            Sesame Seed Oil: SPF 4
            Grape Seed Oil: SPF 4
            Jojoba Oil: SPF 4
            Rice Bran Oil: SPF 2-4
            Sea Buckthorn Oil: SPF 2-4

            Fortunately, there are natural ways to protect yourself from sunburn that you can use instead of resorting to toxic sunscreens. Two non-toxic ingredients that scatter both UVB and the more damaging UVA rays are the natural minerals titanium dioxide and zinc oxide. The most obvious and safest option is to put on a long sleeved shirt, pants and a hat once you’ve reached your limit of sun exposure (you can tell you’ve had enough right when your skin turns the lightest shade of pink). 


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