The dope on Vitamin D and our bio-psycho-social relationship with our star according to Mark Sisson... VITAMIN D AND THE SUNNY SIDE OF LIFE No discussion of the rising and setting of the sun would be complete without acknowledging the powerful impact direct sunlight has on the production of vitamin D, which, as previously stated, is technically not a vitamin but another potent and essential hormone. Within your epidermis, enzymatic ‘bio-factories’ convert cholesterol derivatives to vitamin D when UVB rays of sunlight hit your bare skin. (Yes, cholesterol! Like sunlight, our bodies would not be able to function without it.) The newly created vitamin D is then distributed to receptors located within cells throughout your body, playing a central role in metabolizing calcium; strengthening immunity, cardiac, and neurological function; and, ultimately, gene expression. Overall, some two thousand genes are influenced - or turned on - by vitamin D, triggering elevated levels of beta-endorphins and serotonin. We’re talking about some serious feel-good stuff here! Vitamin D also works to regulate cell growth and renewal, particularly by acting on the P53 gene, the appropriately named ‘DNA proofreader’ gene, which is responsible for overseeing hundreds of millions of daily cell replications. It’s also involved in apoptosis, the natural self-destruction of superfluous or damaged cells before they become malignant. In the absence of vitamin D, however, the P53 gene will down-regulate - or turn off - and the risk of many forms of cancer, including melanoma, will dramatically increase. Without question, the sun has left a deep imprint on our genetic makeup and primary biological processes, dating back some 350 million years, when vertebrates first left the calcium-rich sea for land. Vitamin D synthesis set the stage for creatures to proliferate and become more complex with healthy, mineralized skeletons. Evolutionary biologists report that vitamin D’s ability to boost immune function and destroy invading organisms has been conserved in the genome of all primates for over 60 million years. So, it’s pretty darn clear that receiving adequate vitamin D is an essential component of being a healthy, happy Homo sap sap. And yet a 2009 study published in the Archives of Internal Medicine reveals that 77 percent of Americans have insufficient levels of it in their bodies. In fact, we’re learning that vitamin D deficiency is one of the most disastrous disconnects in modern society. How did this happen? How is it that in the beginning of the twenty-first century, in developed countries, we are seeing a resurgence of all sorts of debilitating health problems, including a rise in cancer and a return of rickets? “vitamin D’s ability to boost immune function and destroy invading organisms has been conserved in the genome of all primates for over 60 million years.” Our sedentary indoor lifestyle is one big reason. And when we do go outdoors, flawed conventional wisdom encourages us to shun the sun, and cover up and slather sunscreen all over our bods, from head to toe. We’re warned of wrinkles and skin cancers with ominous names like malignant melanoma and basal cell carcinoma. But the reality is no scientific evidence links regular, moderate sun exposure to any form of skin cancer. Only excessive sun exposure presents a skin cancer risk, and even then mainly for carcinoma - the easily treatable condition - and not melanoma, the far more serious condition. For every skin cancer diagnosis attributed to excessive sun exposure, there are fifty-five more cancer diagnoses attributed to insufficient sunlight. University of California researchers believe that more than sixty thousand annual cases of colon and breast cancer worldwide can be prevented simply by increasing the intake of vitamin D.1 In fact, recent studies link vitamin D deficiency as the root cause of other health complaints such as depression, fibromyalgia, and muscle and joint pain. Think about that the next time you layer on a thick glob of sunscreen. One with a Sun Protection Factor (SPF) of 8 compromises vitamin D by 90 percent, while SPF 30 blocks 99 percent of vitamin D. (Never mind that a good Primal Blueprint diet and, guess what, adequate vitamin D, bolsters our natural sunburn and sun damage defenses.) Obviously, sun exposure is all about striking the right balance. Too little or too much, and you pay the consequences. So, how much is enough? And what’s the sensible approach? YOU ARE HARDWIRED for your body to manufacture vitamin D by way of sun exposure. MODERN DISCONNECT: an indoor-dominant lifestyle and paranoia about the sun. PRIMAL CONNECTION: sufficient sun exposure over large skin surface areas, or supplement as needed. The darker the natural coloring of your skin, hair, and eyes, the more melanin pigment you possess. Melanin is a natural chemical in your body that protects your skin from excess solar radiation (UVA ultraviolet light), so the more you have, the more you can enjoy risk-free sun time. Those with red hair and extremely fair skin have difficultly manufacturing melanin. If you have fair-to-medium skin pigment, you can easily synthesize vitamin D, but you burn easily. Strive for a slight in-season tan - somewhere between ten to twenty minutes of direct sunlight daily over 25 to 50 percent of your body. Avoid burning, and you will be safe. But even at the equator, the early morning and late afternoon sun is not intense enough to support vitamin D production, so your window of opportunity typically lies between 10 a.m. to 3 p.m. only during the periods of mid-spring to mid-autumn in the latitudes where most North Americans and Europeans live. A good in-season strategy, represented by that slight tan, should keep enough vitamin D cycling through your system year-round. This is because your fat cells store enough vitamin D to get you through the winter months. The darker your eyes and skin, the more time you need to spend in the sun to manufacture optimal amounts of vitamin D. This has become a serious complication for those of African descent living indoor-dominant lifestyles outside the tropics. Recent findings show that African-American males have an 89 percent greater risk of cancer mortality than white men, and have particularly high rates of digestive tract cancers (colon, rectum, mouth, esophagus, stomach, and pancreas) that are strongly linked to vitamin D deficiency. DIALING IN YOUR VITAMIN D STRATEGY Manufacturing vitamin D from sunlight occurs only when ultraviolet radiation is greater than 3 on the UV index, something that is affected by numerous variables: high altitudes (the more intense the UV, the more vitamin D production), reflectiveness of ground surface (light reflected off sand, snow, concrete and water increases vitamin D production; the opposite for grass and other less reflective surfaces), pollution (minimizes UV, and therefore lessens vitamin D production) and obviously time of day, time of year, and your skin pigment. Since ‘maintain a slight tan’ might be too vague of a recommendation for something this critical to your health, it’s helpful to have a basic understanding of how to optimize your vitamin D production, predominantly through sun exposure. Dr. Michael Holick, author of The Vitamin D Solution and one of the world’s leading authorities on vitamin D health, recommends a maximum safe sun exposure time of half the amount of time it takes to sustain a slight (pink) sunburn that is noticeable twenty-four hours later. This benchmark - which Dr. Holick refers to as one minimal erythemal dose (1 MED) automatically factors in all the aforementioned variables. For example, a redhead on a white-sand beach in Southern California in mid-summer can burn his or her skin in a matter of minutes. Someone of medium skin pigment playing on a grass field in New York City in the fall, however, can spend a couple hours in the direct sunlight without burning. If you obtain sun exposure equivalent to half of 1 MED (half of burn time) over approximately half of your skin surface, your body will produce an estimated 2,000 to 4,000 International Units (I.U.) of sun-obtained vitamin D, which, incidentally, lasts twice as long in your body as a vitamin D supplement of the same amount. Knowing this, it becomes clear how insignificant dietary vitamin D sources are, and how important it is to expose large skin surface areas of your body to sunlight frequently during the months of peak solar intensity at your latitude. Naturally, your half a MED exposure time will be an estimate, since there is no reason to sustain a burn in order to pinpoint your 1 MED time! By the way, if you are imagining your dermatologist cringing at the suggestion to expose your fair skin to more rays, go ahead and cover sunscreen on your face, neck, and hands whenever you spend time in the sun. Protecting these vulnerable areas from potential wrinkling and cancerous growths will not materially hamper your body from manufacturing vitamin D. This is because your face and hands represent only a small fraction of your total skin surface and total vitamin D manufacturing potential. Focus on your legs (36 percent of total skin surface), back (18 percent), abdomen and chest (18 percent), and arms (18 percent) for vitamin D production, since they have far less risk of chronic exposure damage and loads of potential for vitamin D production. YOU ARE HARDWIRED with skin pigment aligned with the latitude of your ancestral homeland. MODERN DISCONNECT: living farther from the equator than your ancestors. PRIMAL CONNECTION: more sun exposure and possible supplementation, especially in winter. Still, for a variety of reasons, many of us find it a challenge to expose large areas of our bodies to the sun at midday. For example, you may live at a latitude that is incongruent with our skin pigment and ancestral heritage. Or you may find the sun’s rays in your area are only intense enough to make vitamin D for a portion of the year. In such cases, supplementing with vitamin D can be extremely useful to ensure that you maintain healthy blood levels of the nutrient year-round. A typical small capsule might dispense 2,000 I.U. And, since vitamin D can be easily stored in your skin, you can take several pills at a time and not have to worry about regimented daily pill popping. In the winter months when UV intensity is low, I recommend getting an average of 2,000 I.U. of vitamin D per day. “Conventional wisdom has long touted a good old glass of milk for a vitamin D boost, yet it delivers a mere 100 I.U.” Dr. Holick and other vitamin D advocates recommend that you obtain far more than the paltry US RDA of 200 I.U. per day. Dr. Holick suggests getting 25 to 50 percent of 1 MED over 25 to 50 percent of the skin, two to three times per week. I personally take more because I also love the peripheral feel-good benefits of spending time in the sun. There is zero risk of overdosing on solar vitamin D; your melanin/tanning mechanisms ensure that any potential excess vitamin D is destroyed on the surface of your skin before it enters the bloodstream. Historically, the only real risk of vitamin D toxicity has come from ingesting dangerously high levels of overfortified and mislabeled processed foods. If you have even a slight suspicion that your lifestyle circumstances put you at risk of vitamin D deficiency, it will be valuable to take a clinical approach to the issue. If you have an office job or commute that prevents you from receiving midday sun, live at a latitude in discord from your ancestors, are obese, a growing youth, or pregnant or lactating, or follow a grain-based diet (which can hinder calcium absorption and thus increase vitamin D requirements), this means you! First, I highly recommend getting your blood levels tested. Make sure to request the most relevant and accurate test, which is for the circulating form of vitamin D known as 25-hydroxyvitamin D. The test may be called ‘25-vitamin D’ or ‘serum 25(OH)D.’ The best time to get this test is early fall, when your vitamin D levels should be at their highest after a summer of adequate sun exposure. You can order a simple, painless home test from ZRT Laboratory for $75 (ZRTlab). Your vitamin D levels are represented in nanograms per milliliter (ng/ml). Dr. Holick categorizes values as follows: Under 20 ng/ml is considered deficient. Under 30 ng/ml is insufficient. The ideal range is 40-60 ng/ml, with anything under 100 ng/ml being acceptable. A level over 150 ng/ ml is considered toxic, and virtually impossible to get through sun exposure and sensible eating, as mentioned previously. Second, spend some time calculating your vitamin D manufacturing particulars at this web site: nadir.nilu.no/~olaeng/fastrt/VitD-ez_quartMED.html. This handy tool allows you to input your variables to calculate a reliable estimate of your vitamin D potential for your particular skin pigment, latitude, time of year, and time of day. When getting regular and adequate amounts of UV 3 intensity rays over large areas of your skin proves to be a difficult task, diet and supplementation comes into play. You may have heard certain foods touted as vitamin D powerhouses: wild salmon, mackerel, herring, catfish, cod liver oil, eggs. These all provide good nutrition, but they only deliver somewhere between 200 to 1,000 I.U. on a typical serving - not nearly enough to make a dent in the bigger picture of overall vitamin D requirements. Conventional wisdom has long touted a good old glass of milk for a vitamin D boost, yet it delivers a mere 100 I.U. By contrast, when I play one of my summertime, two-hour Ultimate Frisbee matches (playing for the ‘skins’ team, naturally!) at 34 degrees latitude in Los Angeles, with my Scandinavian skin pigment, my body manufactures about 15,000 I.U. of solar vitamin D. Got Milk? No, but thanks anyway!
Posted on: Tue, 28 Jan 2014 12:00:59 +0000
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