Vitamin D- Are You Getting Enough?

Vitamin D seems to be getting some positive publicity lately, but the tide of public opinion is yet to shift on the importance of sunlight in this equation. While scientists debate the topic, perhaps a conclusion can be reached with some good old-fashioned logic.

A quick stroll around any Walgreens shows the trend these days to lather sunscreen each day to protect against damage from the sun. Sunscreen under your make-up, sunscreen in your make-up, sunscreen for baby, sunscreen for those who are sweating, sunscreen with added tanner, the list goes on. This would all be well and good, except it isn’t working! Our overuse of sunscreen hasn’t stopped skin cancer at all, it is actually increasing! On top of that, people are getting the most dangerous types of skin cancer in places the sun never even touches. Something here just doesn’t add up…

First, let’s break down what role the sun plays in our biochemistry, and why it is important in the first place.

Organisms like plants and algae use sunlight for photosynthesis to create oxygen and other important by-products. Sunlight doesn’t work quite the same way for us, but is still just as important. When we are exposed to ultraviolet B light from the sun or artificial sources, vitamin D3, or cholecalciferol is created photochemically in our skin. Food sources like fatty fish, eggs, and meat also provide D3. However Vitamin D enters the body, it is then transported through the bloodstream to the liver where it is converted into the prohormone calcidiol. Calcidiol is then converted by the kidneys or organisms in the immune system into calationol. Calatinol circulates as a hormone and regulates mineral concentration in the blood (including calcium), function of the neuromuscular and immune systems and gene proliferation (this is the reason for the link between Vitamin D deficiency and Cancers).

Or put more technically (courtesy of wikipedia.com)

“Following the final converting step in the kidney, calcitriol (the physiologically active form of vitamin D) is released into the circulation. By binding to vitamin D-binding protein (VDBP), a carrier protein in the plasma, calcitriol is transported to various target organs.^[8]

Calcitriol mediates its biological effects by binding to the vitamin D receptor (VDR), which is principally located in the nuclei of target cells.^[8] The binding of calcitriol to the VDR allows the VDR to act as a transcription factor that modulates the gene expression of transport proteins (such as TRPV6 and calbindin), which are involved in calcium absorption in the intestine.

The vitamin D receptor belongs to the nuclear receptor superfamily of steroid/thyroid hormone receptors, and VDRs are expressed by cells in most organs, including the brain, heart, skin, gonads, prostate, and breast. VDR activation in the intestine, bone, kidney, and parathyroid gland cells leads to the maintenance of calcium and phosphorus levels in the blood (with the assistance of parathyroid hormone and calcitonin) and to the maintenance of bone content.^[23]

The VDR is known to be involved in cell proliferation and differentiation. Vitamin D also affects the immune system, and VDRs are expressed in several white blood cells, including monocytes and activated T and B cells.^[24]

Apart from VDR activation, various alternative mechanisms of action are known. An important one of these is its role as a natural inhibitor of signal transduction by hedgehog (a hormone involved in morphogenesis).^[25][26]”

So what does this mean for us? In humans, Vitamin D is much more than just a simple vitamin that we need to hit a target RDA of. Vitamin D is a hormonal precursor and science is constantly linking deficiency of Vitamin D to increased incidence of many diseases. Ironically, while Vitamin D is reality available (at least part of the year in most parts of the world) for free if produced from sun exposure, people are surprisingly deficient in it these days.

Vitamin D3 can be obtained by adequate sun exposure or by oral supplementation, but which is better? For years and years (basically all of human history until the last few hundred years) vitamin D was obtained from the sun in varied amounts based on proximity to the equator. Obtaining Vitamin D from food wasn’t really a feasible option, since most foods didn’t have any mentionable level of Vitamin D.

People who got the most sun exposure because they lived in hot areas of the world developed excess melanin (a darker skin pigment) to block burning while lighter skinned people could produce Vitamin D (and a sunburn) a lot more quickly. This system worked really well when in the time when people lived in the same basic area their whole lives, but now a light-skinned person like me could go live in Ecuador or a naturally dark skinned person could move to Moscow. For this reason, people with lighter skin need less sun exposure to get their vitamin D, while those with darker skin need much more sun to get the same amount.

These days, health experts propose that vitamin D deficiency is the most rampant and dangerous vitamin deficiency. What then, is the best way to get this all-important vitamin, the sun or a supplement? No matter how Vitamin D is obtained, it ends up in the exact same form once it hits the liver (as long as an oral form is D3). While I would personally suggest getting Vitamin D from the sun if possible because of the other benefits of sun exposure, the most important thing is to just get Vitamin D. If sun exposure is not possible or not feasible, supplementing orally is necessary. The amount of Vitamin D a person should take varies by person, and a blood test is the only certain way to tell if you are getting the right dose orally (the body regulates this quite well if you are getting it from the sun). You want to get your 25(OH)D levels tested and aim for getting them between 50 and 70. Experts are now estimating that most people need at least 10 times the suggested RDA (400 IU) of Vitamin D to accomplish this.

If you are fortunate enough to be able to get your vitamin D from the sun, your body will tell you how much you need and when you have enough (hello, sunburn). The goal is to get adequate sun and not ever burn. For light skinned people this may be only 15-30 minutes, but darker skinned people may need two hours or more!

So then, lather on the sunscreen, right? Not so fast! The chemicals in sunscreen have been linked to cancer themselves (hmmm, could that be the reason for the increasing skin cancer rates?).  Chemicals in sunscreens are also found to create free radicals in the body and produce an estrogenic effect (man boobs anyone?).  So how ever do we protect ourselves from over-exposure to the sun? After realizing that most people aren’t getting enough to begin with, the logical answer once you have gotten your sun exposure for the day… get out of the sun! Find some shade, wear some clothes, but get out of the sun. If you are at the beach or on an adventure race, consider a natural sunscreen or a pure zinc oxide formula.

Of course, many people will have trouble accepting the fact that sun exposure is so important, even as study after study show the importance of vitamin D. Of course, it is up to you, ignore the sun and don’t supplement more than the RDA of the big D if you aren’t worried about:

• Cancer- Research is now estimating that 75% of cancers can be prevented by adequate consumption of Vitamin D.
• Calcium Levels- Vitamin D controls calcium and phosphate levels in the blood and contributes to bone growth and bone strength
• Your Immune System-Ever heard of those “t-cells” that protect your body against bacteria and disease? Vitamin D is crucial in their creation and function.
• Inflammation- Lack of Vitamin D can cause inflammation in the body, then again, so can grain consumption. Have joint pain, soreness or inflammation? Cut the grains and hit the beach!

Other things to remember:

• Vitamin D helps calcium absorption, but make sure you are getting the calcium from diet or supplements.
• Deficiency of magnesium can inhibit vitamin D function, make sure you get that too!
• Eat proteins and fats
• Don’t eat grains
• Jump into sun exposure slowly if you aren’t used to it, though many people who switch to a no-grain no polyunsaturated or hydrogenated oil diet notice a much higher resistance to the sun.

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