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.

You know, I think you’re definitely onto something here. Another commenter noted a study showing an independent benefit to sunlight exposure in animal models of multiple sclerosis. Sunlight exposure improved outcomes without appreciable increases in vitamin D, or at least not enough to explain the benefits entirely. That’s just a single type of a certain disease, and it’s just an animal model, but it displays a definite benefit to sunlight independent of vitamin D. There may be even more that we just don’t know about.

Besides, there are the benefits exclusive to sunlight of which we’re already aware: warmth, barbecues, gradual tans, and simply being outside and enjoying life. It’s pretty tough to do that holed up indoors, even if you’re pounding the vitamin D caps religiously. They’ll never replace a grueling workout under the sun, or a quick sprint session along the coast on a bright day.

also, it it worth noting that according to the literature, a small percentage of people seem to react unusually sensitive to vit D supplementation. those people will show an unexpected rise of the blood calcium levels together with the D supplementation. for this, it is recommendable to also measure the calcium level before and during supplementation, to be sure to exclude even the slightest risk of overdosing.

Absolutely. If you suffer from hyperparathyroidism, check with your doctor before supplementing with vitamin D. The condition can often be exacerbated or even caused by vitamin D deficiency, but it can also result in hypersensitivity to vitamin D or over-conversion into the active form. Monitor your calcium levels, too, to make sure you aren’t over-converting D. Excessive levels of active D will generally result in higher serum levels of calcium.

Mark, thanks for the informative article. However, when publishing a chart such as the “big benefits” chart, it would be much more persuasive if you gave a reference in the scientific literature to substantiate the data. The data is, after all, very quantitative. Please provide a reference. Thanks. (And, by the way, just to stipulate, I am not a primal routine skeptic. I’ve been on a primal routine now for 2 months. But I am a health care professional, and need data confirmation.) Thanks.

Sure thing. I pulled the graph from this PDF on Grass Roots Health. It comes with the references and explanations for the “X”s (“reasonable extrapolations” from existing data). Hope it helps.

Then about a month ago I was on a site and listening to an audio interview of a doctor who said that higher glutathione levels gave protection against sunburn. Boy did my ears perk up. Unfortunately it was just a side comment so he did not elaborate. (For those who don’t know, and I was one of them, glutathione is an antioxidant produced in almost every cell in the body.) However he did say that when people switch to a healthier diet that their glutathione levels tend to go up.

That’s all I know about that for what it’s worth. I thought it was pretty interesting though.

There is a bit of literature on glutathione and sunburn indicating some potential photoprotective benefits to glutathione. In hairless mice exposed to moderate levels of UVB, those with depleted glutathione levels in their epidermis saw more sunburn than those mice with normal glutathione levels. Interestingly, there were no significant differences between the two groups when exposed to high levels of UVB. In another hairless mice study by the same authors, oral glutathione supplementation increased skin glutathione levels and reduced sunburn cell development in mice exposed to UVB.

According to the Vitamin D Council, vitamin D increases glutathione concentrations in the body. This is a likely explanation for the widely reported photoprotective effects of vitamin D supplements.

What would you suggest for people who tan to start, but burn with too much exposure to the sun, in regards to sun screen? In the summer months I’m outside constantly during the day, and while I get a nice base tan, I also will burn without sunscreen after about 45 minutes.

That’s pretty standard for light skinned people, even those with a good tan or plenty of sun exposure experience. Forty five minutes is generally plenty of time to generate your vitamin D allotment for the day, so I wouldn’t worry about the burning – that’s just a natural indication to get out of the sun and into shade! The best sun screen is shade or clothes, of course, but you could also try increasing your vitamin D levels (see the previous section on photoprotective glutathione levels rising with vitamin D levels). If you insist on opting for actual sunblocks or creams, check out a mineral sunscreen. Zinc oxide protects from both UVB and UVA, and I believe there are some clear versions available. Otherwise, make sure the block you’re using blocks both UVA and UVB. Also watch out for sunscreens that employ the vitamin A derivative retinyl palmitate, which is photomutagenic when exposed to UVA in mouse lymphoma cells.

Whatever you do, don’t rely on sunscreen all the time. Listen to your skin and get out (or in) when you start to burn, because that’s usually plenty of time for vitamin D production.

A little off topic here. I told a friend (I call him a vampire) who never goes in the sun (and when he does he is white from the sunscreen) and eats grains that his brittle bones are going to snap in half at the age of 40…..too harsh? His father just had a hip replacement at 60 years old. He avoids the sun also….coincidence? I THINK NOT!

I can’t say for sure, of course, but vitamin D supplementation has been shown to reduce osteoporosis and falls in older folks, especially the really bad falls that result in bone breaks and hip replacements. Age forty and onward is when our lifestyle really begins to catch up with us. We can usually get away with a bit of vitamin D deficiency, a lack of resistance training, and poor dietary practices for the years of invincible youth, but not once we hit forty or so. Then, all bets are off, and we’d better get our intakes in order. And if your buddy is eating as many grains as most grain eaters do? He’s going to need even more vitamin D than usual.

Keep on him about it, because he’s your friend and you care and it’s serious, but use a bit of tact. People can be fragile and defensive about diet and sunlight. Kid gloves may be warranted.

Other stuff of interest:

Dr. Kurt Harris has a nice series on vitamin D: here, here, and here.

Primal Muse has some great stuff on vitamin D, sunscreen, and sunlight.

Ned over at Health Correlator also has some good ones: here and here.

Rather esoteric ruminations on vitamin D courtesy of Peter from Hyperlipid (but then again, that’s partly why he’s so great): here and here.

One reader sent in a link to a simpler vitamin D calculator.

Thanks for reading, everyone. Now get outside and get a little sun!

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