These days many of us go to work in the dark and leave greeted by the same. Those lucky enough to have windows next to their desks or work stations might think, “Hey, at least I get some sun exposure during the day.” But how does sun exposure through glass compare with direct sunlight? One reader brought up the topic this week.
I work in an office and have a big picture window in front of my desk. Don’t get me wrong – I love the light and all, but my friend told me you don’t get any real sunlight benefits (vitamin D, etc.) through glass. Is that right? I’m guessing a tan is out as well. What’s the story on what gets through and what doesn’t? Love the site by the way.
Okay, I’ll admit it. I may have spoken out of turn a couple week’s ago when I tried to completely cover vitamin D in a mere three posts (Deconstructing Vitamin D, Vitamin D: Sun Exposure, Supplementation and Doses, Vitamin D: Confounding Factors). A bunch of questions popped up in the comment boards – so here’s my attempt to tie up the loose ends and cover any further wrinkles in the vitamin D story.
Living in Los Angeles, I am lucky enough to be able to get much of my Vitamin D from sunlight all year round. I still take an oral D3 supplement when I’m traveling, too busy to spend much time outside, feel a sniffle coming on, etc. I take 4-10k IU D3 from Carlson’s drops (2k IU per drop). I prefer to get my D3 from the sun, however. It is not what I know I’m missing that concerns me, but what I don’t know that I may be missing. Sunlight may yield other health benefits beyond just Vitamin D production. Oral dosing with D3 won’t give you these other possible benefits.
And I’ve also noticed that switching from a SAD to a primal diet has dramatically improved my sun tolerance (and put a metabolic disorder–porphyria–into remission.
Yesterday I recommended 4000 IU of vitamin D each day as a good starting point for most people. Though, it’s difficult – nay, impossible – to provide a perfect, universal prescription for vitamin D3 intake. People, and their lifestyle behaviors and environmental conditions are just too different. It’s like with diet. Everyone does well with the basic building blocks, stuff like meat, fat, vegetables, fruit, and nuts, but the optimal ratios are going to differ for individuals based on genetics, dietary history, activity level, and glucose tolerance. Everyone needs vitamin D, but multiple confounding factors must be taken into consideration to determine the right dosage. To start with? Yes, 4k is a good starting point. From there, though, things get considerably more complicated – as they always do.
Now, I don’t want to overcomplicate things, however. The same basic advice holds: get unfiltered sunlight, avoid burning, and take supplements when sunlight is unavailable. But I do want you to be aware of certain factors – environmental, climatic, dietary, genetic, etc. – that may affect vitamin D3 production, requirements, and availability.
From the presence of vitamin D receptors in our cells and vitamin D factories in our epidermis, along with the central role vitamin D plays in calcium metabolism, immunity, and gene expression, it’s pretty clear that having adequate vitamin D is an essential component of being a healthy, successful homo sapien. And yet, many health practitioners suggest that vitamin D deficiency is one of the biggest nutrient deficiencies in modern society. The question, then, arises: What’s the best way to get enough vitamin D – via oral supplementation or sunlight?
To determine that, let’s examine a few common questions surrounding the various modes of intake.
Before phototropic plants began bending toward sunlight, before jellyfish developed ocelli, the light-sensing organs that allow them to distinguish between up (sunlight) and down, before the bikini-clad beach denizens began tanning en masse, and before the first house cat followed the sliver of sunlight around the room all afternoon, our primitive, microscopic marine forebears were flourishing by converting the sun’s energy into chemical energy usable by biological life. You’re probably aware of photosynthesis, the process by which plants, algae, and other organisms do it and produce byproducts like oxygen, but even the unicellular archaea that do not produce oxygen utilize sunlight for energy. And if you aren’t obtaining energy directly from the sun, you’re probably eating the organisms that do. Either way, sunlight directly or indirectly supports all life (well, except for the chemoautotrophs living in deep sea hydrothermal vents feeding off of inorganic energy sources like iron, ammonia, or sulfur).
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