Vitamin D: Sun Exposure, Supplementation and Doses
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.
Is it natural?
This is a big one. We obviously care about how nature shaped human evolution. Shouldn’t then our mode of obtaining vitamin D also be “natural”?
For us humans, getting vitamin D from sunlight is the clear winner if judged by this standard alone. We are basically hairless, upright apes for a reason, with hefty D3 requirements, and before oral supplements appeared, dietary vitamin D was not a very reliable source. We had to get it from the sun. Today, we’re still those same hairless, upright apes (albeit with different fashion trends and hygiene sensibilities), and we can still obtain vitamin D from UV-B radiation. Personally, I prefer getting my D3 from sunlight, simply because it’s enjoyable to spend time in the sun and it’s an effortless way to get something that’s critical to my health. But I don’t think it’s necessarily “better” than getting it through supplements. Nature’s way is quite often better, or at least more congruent with how we’re “intended” to work, but that doesn’t always preclude the effectiveness of modern methods.
Additionally, as a little added factoid, this is essentially the way fur-bearing mammals and birds obtain the bulk of their D3: orally. The oils in their fur/feathers produce D3, and preening/self-grooming results in oral intake, with diet rounding out the rest. Skin production is either inadequate or nonexistent. Now, we aren’t dogs or sparrows, but the mechanism for oral intake clearly exists across a wide variation of species.
Yet another question arises: Does oral D3 differ – qualitatively – from solar D3?
Let’s examine the pathways – let’s see what happens when you produce or swallow vitamin D3.
When UV-B reacts with the 7-Dehydrocholesterol in your skin, cholecalciferol (D3) is produced and ends up in your liver, where it’s hydroxilated into calcidiol, also known as 25-hydroxyvitamin D or 25(OH)D.
When you swallow cholecalciferol (either in food or supplement), it ends up in your liver, where it’s hydroxilated into calcidiol, also known as 25-hydroxyvitamin D or 25(OH)D.
From that point onward, it’s all the same. It’s all calcidiol, ready for storage in fat tissue or dispersal to the kidneys for conversion into calcitriol, also known as 1,25(OH)D. Calcitriol is the active hormonal form whose primary role is to regulate blood calcium levels. If there’s enough calcidiol left in the tank after the calcium duties, it gets sent to other tissues in the body to be converted into more calcitriol to fulfill even more roles. That’s where all the immune system/cancer cell/heart health/insulin sensitivity benefits begin to kick in, and it explains why having plenty of vitamin D available – beyond what’s only required to avoid rickets and monitor blood calcium – is so beneficial.
Both oral supplements/dietary sources and sunlight can get you there. Qualitatively, they are identical. The only difference is in the dosage. With oral D3, dosage can be consciously controlled, but it’s also subject to human error (or foolishness). You could conceivably keep popping capsule after capsule and end up with toxic blood levels. It’s difficult to do (one official site suggests the level might be in the millions of IUs), but it’s technically possible. When you sunbathe, on the other hand, you don’t consciously flip a mental switch that shuts down D3 production. Instead, you burn, or you grow uncomfortably hot. You – quite naturally – opt out of sun exposure before it gets too intense. As your skin darkens and you begin to tan, it produces less vitamin D, and you can stay out longer without burning, but it’s generally true that sun exposure up to the brink of turning pink is safe and will net you plenty of D3. In addition, it’s interesting to note that once you have produced enough vitamin D through sun exposure, those same UVB rays will begin to prevent excess vitamin D production by degrading existing cholecalciferol. Ain’t homeostasis grand?
So – sun or supplement? What should I do?
Take stock of your living situation. If the sun is available regularly where you live, go that route whenever possible. It’s free, it’s safe, it’s easy, and it’s enjoyable. Avoid burning, of course, and you’ll be safe. I find it inconceivable that the amount of sun exposure necessary to produce 10,000 IU of D3 (about 20-30 minutes of afternoon sun for light skinned folks; a few times that for dark skinned folks) will also kill you and give you skin cancer.
As with anything, though, ease into the sun. The pasty, mostly interior set will want to treat full sunbathing like learning to barefoot sprint after a lifetime of dress shoes – they’re coming from a position of weakness, of sheltered living. Five minutes of unfiltered rays can turn a freckled redhead lobster-pink, sore, and resigned to indoor living. Just be careful. Ease into things. Learn your limits, and throw on a shirt or find some shade before you burn.
Eating the right foods seems to confer greater natural skin protection against the sun, at least anecdotally. I’m not exactly the best case subject to determine this, as I’ve spent much of my life fairly tan with regular sun exposure, but you hear time and time again about folks who cut the grains, sugar, and industrial vegetable oils, replaced them with veggies, meat, and animal fats, and have never had any issues with the sun again. Nutritional deficiencies do have the tendency to potentiate existing problems or jumpstart/trigger health maladies, so I wouldn’t be surprised. Besides, we’re eating this way regardless. We might as well pick up a few additional theoretical health benefits along the way.
We can’t all bask in the midday sun (if such a thing even exists in our neck of the woods), nor can we even reliably count on there being adequate sunlight on a regular basis. For those of us unable to run shirtless and shoeless through a sun kissed meadow, the last of its residual morning dew having finally evaporated, from noon to 12:45, our option is oral intake.
Certain foods get touted as vitamin D powerhouses: wild salmon, mackerel, herring, cat fish, cod liver oil, eggs. Eat these, but don’t expect to increase your 25(OH)D levels much. Don’t eat the fortified, processed junk which, in the case of cereal grains, actually reduces calcium absorption. It’s a good thing they’re usually fortified with meager amounts of vitamin D, just enough to avoid rickets and keep blood calcium relatively under control. Remember, the body preferentially uses available D for calcium regulation, so it’ll mobilize every last scrap when it comes to matters of the bones – but that is far from optimal. When you eat grains and other junk, you’re increasing your D requirements.
No, food will help, but it won’t suffice. You need something stronger. Might I suggest licking the nearest sunbathing dog? (Would that actually work? I know that most vitamin D3 supplements are isolated and extracted from the fat in lamb’s wool; perhaps a similar concoction could be devised from oily dog fur).
In all seriousness, take a good D3 supplement if you can’t get real sunlight. As long as you don’t go overboard on the dosage, you’re good to go. If it’s not in an oil-based capsule, just take it with a bit of fatty food (not a stretch for an Primal eater). It travels the same pathway and results in the same benefits. It’s always easier to just let nature take its course, but it’s not always realistic.
A good general rule is 4000 IU per day supplemented. That’s what I take during winter time and when I go a few days trapped indoors and without sun (as I was last weekend while at the Book Expo of America in New York). Get your 25(OH)D levels tested before you start supplementation, take the 4k IU daily, and get them tested again after two months. Aim to get your levels up around 50-60 ng/mL, which is where most of the big benefits seem to kick in. If you don’t respond well to 4000 IU, feel free to increase the dosage. Given that we can make around 10,000 IU in well under an hour, supplementation up to that level is well tolerated.
I’ll end it here for now, with more coming tomorrow. It’s a big topic and there’s a lot to cover.
Get Free Health Tips, Recipes and Workouts Delivered to Your Inbox
Posted By: Mark Sisson
Mark,
Thank you so much for this!!
Living in Naples, I get my sun. But I also do supplement as I’m not retired…yet
So during the week when I’m in the office for most of the day, I take 4,000 a day. I have not had a cold or bug in 3 years. (not bad with 4 kids in grade, middle and high school,)
Can you talk a bit more about taking higher doses perhaps? ie; air travel, cold coming on etc?
Thank you Mark.
Marc
Marc
Mark, I have read about recommendations on taking 2 large bolus doses a week of oral D3 versus 5000 IU per day. For example, take 25000 IU twice a week for better D3 levels in your body. Any comments?
D is fat soluble. You could take your D once a week if you want to and be fine.
Thank you for this series of very informative posts. I have been wrestling with the Vitamin D, K, Calciun, and Magnesium connection for a while.
Any thoughts about how much UVB absorbtion is compromised by an overcast day?
I actually just got my vitamin D levels tested last week. The results came back as 30ng/mL (this labs ref range was 30-80) and I was told taking a supplement was “optional”. I’m now taking a loading dose of D3 for 1 month every day (10,000 IU) and then I’ll drop back to taking that every other day. I think I will have them retest in 2 months just to see.
It may take a lot longer than a month or two to see a big increase in your D levels. After discovering my low levels, my doctor recommended 10,000 IU of D3 per day. On that dosage, it took me a year to increase my levels from 32 to 70. Now, I take 5,000 IU as a maintenance dose daily. That was also with a completely gluten free and 80% paleo diet.
Mark,
Nice article. Question about the “big benefits” chart you posted near the end:
–If a person has a serum level higher than the max optimum benefit for say, heart attacks (~35ng/ml) and supplemented to maintain a level to avoid fractures (~45ng/ml) is there then a negative effect on the incidence prevention for heart attack?
–And do you know what the “X” indicates for a given incidence of disease and serum concentration?
Mark, all of my friends teeth are breaking, she is a vegatarian that eats a diet very high is carbs and a lot of grain based foods, but no vegtables (funny), her dentist is telling her it is because her fillings are expanding, this sounds like bull shit to me, could low vitamin D be the cause of this, please let me know what you think, and if there any thing that will help, please don’t say eat meat because i am already trying to get her to do that.
Thank-you.
If she has silver (mercury) amalgam fillings, they do corrode and expand, causing teeth to fracture. One good reason, along with getting mercury out of your mouth, to have them safely removed and replaced with a composite material. BTW, it’t touted as a benefit that they “expand” aka corrode over time, since the filling to tooth seal becomes better. Causing your teeth to crack apart – not so good.
apart from the fact that amalgam fillings indeed can expand with the applied chewing pressure and time, it is possible that your friend has a vitamin D and/or vitamin K2 deficiency. both are needed to properly deposit calcium into the teeth. considering that K2 mainly occurs in meat, that could be one factor. google vitamin K2 for more information.
considering her lacking diet, i’d recommend that she takes a high-quality multivitamin incl. a calcium/magnesium supplement plus a specific vitamin D+K2 supplement, at least for the time being. you can find the D+K2 combo at the usual online shops. also, if not meat, at least make her eat wild fish and eggs regularly
The best sources of vitamin K2 are fermented foods, especially cheeses (the most plausible explanation of French paradox) and natto (a soy dish popular in Japan). Natto contains the highest concentration of K2 of any food measured; nearly all of it is present as MK-7, which research has shown to be a highly effective form.
Any recommendations on what supplements to take? Brand? Type? (capsules, drops, etc?)
Love this sun topic…thanks
Vitamin D is the new Vitamin C. I had my levels tested just a few months ago and was at 24ng. Anything below 25 is considered “deficient” or so my physician says.
The benefits of Vitamin D are MASSIVE and definitely shouldn’t be ignored. Thanks for covering, Mark!
Interesting about the sun/skin tolerance.
I am very fair-skinned and used to burn very easily. After 3 years of eating primally and supplementing vitD, I assumed it was something about the supplementation that caused a marked reduction in burning. It didn’t occur to me that the increase in nutrient quality might be the difference.
After decades of burning, it’s lovely to be out in the garden for hours soaking in the natural vitD, without suffering the after-effects.
Same story here, I assumed it was d3 but didn’t think of the highly nutritious food I was eating making me less succeptable to burning. Being fair skinned and getting tan and not burning is a whole new experience for me this year….it’s exciting!
Susceptibility to sunburn is caused by excessive linoleic acid in the diet. AKA, those vegetable oils that the Primal Blueprint tells you to avoid.
I attended one of Barefoot Ted’s classes, and my dark-skinned Colombian wife and blonde, blue-eyed me stood side by side in the sun in Central Park for 2.5 hours. For the first time ever, she burned and I did not.
That was the day she adopted the Primal diet.
She still can’t believe what a difference it has made for me. I used to roast after an hour or two in the sun. Now, 5 days in Florida with no sunscreen and no sun burn. It’s pretty unbelievable.
So now I’m getting my Vit-D the old fashioned way, and with a big smile on my face.
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). I think
“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.
Aaron, you’ve summmed up the supplements fallacy in two sentences. You’re so right.
Mother Nature has it’s own agenda, we need to respect it and not try to “improve” it and “optimize” it… We’re fools if we think we can take shortcuts to our health…
I have found that taking cod liver oil and eating lots of butter has helped me tolerate more sun exposure. I don’t burn as easily and recover faster from a light burn than I used to. So taking cod liver oil is not just good for its content of vitamin D but also for being able to stay out in the sun without burning.
Also coconut oil is by far the best topical sunburn recovery method I’ve tried.
I lived in Central Otago New Zealand when I was a kid. Extremes of temperature and very dry. Our mother always treated sunburn (that usually only happened late spring) with sour cream. Stank a lot and the dogs loved us. It was an almost instantaneous relief from the burning and next day the red was gone. We always had plenty of cream as we kept a house cow.
Hey that is very interesting! I heard of using milk to relieve burns from hot peppers but never tried it on a sunburn. I think my cats would love that too.
Since hot peppers don’t actually burn anything, it’s difficult to compare in this manner.
They irritate nerve endings, creating a burning sensation, no actual tissue damage like a radiation burn (sunburn).
Milk (fat) tends to take away the sensation caused by capsaicin (chemical that ‘burns’ in hot peppers) as it is attracted to the fat and carried away from the nerve endings.
Since going primal in February, I’ve spent almost every lunch break with even a little sunlight at the park – either napping with my shirt off or sprinting in shorts and T-shirt. It’s hard to say how much of my improved health is attributable to the diet and how much is the sunlight (vitamin D), but it all works together. One thing is certain: I’ve gone from pasty and doughy, to tanned and slim. I like it a lot better!
if one comes from a severe deficiency, 4’000IU/d will not get you far. i took 5’000 for 3 month and barely reached 40ng. everything <=40ng is *not* enough to re-saturate all bodily tissues with D3 (from 40-50ng, the 2nd metabolic pathway begins to kick in). therefore, depending on your initial level, you should aim rather high for the first few weeks (like 10-20kIU) to be sure to overcome the 40ng bump. then retest, and adjust down to like 4-10kIU. up to 20kIU/200ng, no harm is to be expected according to the research i know.
Mark, just curious if you know anything about idiopathic guttate hypomelanosis. Is it sun related and can it be reversed. Not much on the web about it and since CW is out, what the go with this?
Rob, I have this condition and my dermatologist didn’t seem too freaked out about me getting some sun. I’m just worried that if the white spots have no pigment, is it safe for them to get sun exposure? Let me know if you find any answers. I’d appreciate it.
How can tanning beds be effectively utilized?
I know that UVB rays are the “burn rays” and higher-end tanning beds don’t have them. So going for the cheap beds appears to be the best option.
But what about lotion? The stuff you get specifically for beds has an ingredients list that looks like a commercial salad dressing ingredient list. (Now that’s scary!) Should I use coconut oil as others have mentioned?
Or should I just start taking an hour-long lunch break and head out to the nude beach? Haha.
Why is there only 800IU of Vit D3 in the daily dosage of the Master Formula? I’ve been supplementing with 1,000IU daily + trying to get 10 minutes of sunshine daily.
those higher vitamin D recommendations are of rather recent date, so i guess mark first needs to sell of his existing stock before he can request a new, reformulated batch from his supplier.. but it certainly would not do harm to give a free bottle of 2000IU D3 with each order as long as this is the case.. right, mark?
@Qualia and @kathy,
I update the DCMF every year based on new science. This year we have increased to 2,000 IU per dose to reflect the latest science – including the requisite safety analyses. The new formula is in production now (based on the exceptionally high standards of GMP production, it takes at least 16 weeks from start to finish for most of my products now).
I am also introducing (very soon) a separate vitamin D supplement, which will allow anyone to adjust D levels day-to-day or beyond the DCMF dosage.
My doctor just told me to stop taking most supplements, except for Vit D and fish oil. He said to stop taking calcium. I was using Garden of Life GrowBone Calcium blend that included stronthium. He feels taking supplemental calcium can be dangerous and deposit in the arteries and elsewhere.
I live in Phoenix and after spending all summer in the blazing noon sun and dosing with approx. 2K of Vit D capsules, my September level of VitD was only 37.5. Weird huh?
My question is..would it be dangerous to just take D alone without taking supplemental calcium and relying on my food source for it?
Is there a reason Vitamin D is included in DCMF and not just as a separate supplement? I feel I am more anxious when I take too much Vitamin D, and for this reason I haven’t been taking recommended amounts of DCMF like I would like to. I’ve been looking into other multivitamins for this reason.
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.
All one should or can know about Vitamin D can be found at the website of the Vitamin D Coucil:
http://www.vitamindcouncil.org/
If special problems are involved, like the sensititivies mentioned by qualia above or other disease states, Prof. Holick, the “father of Vitamin D”, gives detailed hints here:
http://www.vitamindhealth.org/?p=63
Greetings from “Old Europe”
guzolany
Nope, no mention of sensitive reactions in some people.
But I have read in in numerous blogs.
I think it is very good idea to get your vitamin D levels tested. Working clinically with clients I have found that even when people are getting sufficient sunlight and/or supplementation, Vitamin D levels are often still in the 20-30 range.
Their are quite a few factors that can effect the conversion of Vitamin D in the liver to 25(OH)D.
Things like the amount of body fat, activity of the enzymes in 25-hydroxylase activity, malnutrition and the effects of aging and disease.
I think this probably explains why many people are able to tolerate sun exposure better once they improve their overall health.
Thanks qualia for the note about sensitivity to D3 Supplements The first time I ever experienced angina was after my doctor prescribed the 50K IU vit D capsules 2x times a week. (I was at 11.8 ng! in March 08) I can tolerate the 400 IU’s that are in the kids multivitamins and try to keep up the gardening! I’m rocking at 31 and my new PCM is still on me for an upward trend or he’s putting me on supplements. I’m not perfectly primal, but everything is better when I stick to the plan!
personally, i’m also a bit sceptic of the usual megadoses that doctors use to give their patients in a single day. although D3 is fat soluble, and therefore could *theoretically* be absorbed and stored rather rapidly, the human body normally does not produce more than 10-20kIU max. from sun. also, the body has some additional metabolic security measures for D3 to be regulated within a certain limit which indeed can be overwhelmed by doses not normally occurring. personally, i try to stay under 20kIU per day. for additional information see http://is.gd/cA2oD chapter: “Dose-response curve of 25(OH)D concentration versus vitamin D intake”
Thanks Christine,
I’m interested in exploring this further as I myself only seem to tolerate a dose of D3 under 2000 IU. Anything above instantly causes angina and a running nose. I’ve tested it numerous times and it always does. Sunbathing all day (which would produce MUCH more D3) does not have that effect.
What supplement did you take ?
If we can produce up to 10,000 IU via sunlight, why is the daily recommended dose found on the back of vitamin supplements so low?
I believe 400IU was the minimum amount to prevent rickets, which is the reason for the low amount on supplements. I agree that it’s stupid.
All of the recommended doses are completely out of whack. I simply use them as a guide.
Take Vitamin A for example… 1 carrot has all the Vitamin A you need in a day. One sweet potato has 600-700% of the vitamin A you need in a day… Kale has like 10,000%, or maybe its spinach?
Basically, the numbers mean nothing. 400 IU for vitamin D3 means what I say it means. Spend time outdoors – get a tan, just don’t burn to the point where it hurts!
Toad, carrots and sweet potatoes have beta carotene (and other carotenoids, I imagine), NOT true, pre-formed vitamin A, which comes exclusively from animal sources. The conversion rate of carotene to Vit. A is as high as 10 or 20 to 1, in other words, a given amount of beta carotene is worth 1/10th or 1/20th the amount of Vit. A. And many people, such as the very young, those with diabetes, etc., can’t make the conversion at all, according to WAPF articles. The carotenoids are *also* useful as antioxidants and possibly for other reasons we don’t know yet, but they aren’t useful as a substitute for true Vitamin A (retinol).
I second that. The conversion is very difficult…true vitamin A = retinol is only found in animals, such as their eyes. (e.g. fish eyes)
Also without having enough D3 the ‘fake’ vitamin A’s in supplements quickly turn toxic. A has to be taken in conjunction with D. (WAPF)
With all the sun topics around: Does anyone know if all the “get out into the sun stuff” is OK for people with many (as in: a lot) naevi, too?
My doctor always told me those probably increase the risk of getting skin cancer a lot when exposing them to the sun, which is why I mostly go out in protective clothing and LSF 50+ when the sun is shining a lot. I’m not sure how much of a risk it really is, because I’ve read many different opinions about it, and I’m not sure who’s right anymore.
i’m no doctor, but all i heard/read so far about this is indeed that the cancer risk is directly proportional to the total number and size of the birthmarks. so, personally, i wouldn’t take the (unnecessary) risk, and simply supplement the D3 with pills while still protecting the skin as usual (and let them get checked regularly by a dermatologist).
Thanks. Yeah, I guess you’re right; With the possibility to supplement Vitamin D3 it’s probably the best thing not to take any risk.
Oh, by the way: LSF of course should’ve been SPF. LSF is the German word for it (Lichtschutzfaktor).
Just found this…..http://www.second-opinions.co.uk/sunlight.html…..interesting read.
As a long time owner of various pets, what about a UVB reptile lamp aimed at a non-tan portion of my body while I am at home for ~15min? I feel that the tan that I am developing and my genetics will require me to stay out longer than I have time for before and/or after work. I’m having outdoorsly fun every weekend, but was just thinking of an alternative to taking supplements on a June gloom (Ahhh! it’s back!) weekday. Just trying to think outside the box…the boyfriend thinks it’s nuts but the thought of me reading the paper with a lamp on my bum got some good laughs. What do you think?
Hi PRana
From
http://www.vitaminddoc.com/d3def_sexual_perf.html
“In 1939, Dr. Abraham Myerson measured initial levels of circulating testosterone in men and exposed their various body parts to UVB light.
After five days of chest exposure sufficient to cause reddening, circulating testosterone increased by 120%. After eight days without additional UV exposure, testosterone returned to initial levels. When the genital area was exposed, testosterone levels increased by 200%!”
As a 52 yo male, I have my UVB reptile lamp aimed to maximize my T levels.
My wife has not made any comments yet,
but she considers me crazy.
That’s enough to convince me to give it a try. Hey, it’s working for the vast number of pet reptiles out there too…
Thanks Mat, very cool article!
For those who want to get their Vitamin D levels tested, D*Action is a great way to do it (http://grassrootshealth.net/).
It is an ongoing epidemiological study on Vitamin D, so the cost of a test is subsidized. They mail you a kit, you prick your finger and send back a blood dot, and they send you your results. Prices have changed but I think a test is about $50 right now.
As someone who lives in a sunny climate, spends some time outdoors every day, and takes cod liver oil every day, I was very surprised to find my Vitamin D levels extremely low before I started supplementing at ~4000IU/day. Test!
I love these sunlight articles. Perfect timing for them too Mark! You obviously planned it.
Over memorial day weekend I played 45 holes of golf. I put on zero sunscreen even though I was in mid 80 degree weather. I just stayed in the shade when possible and, well, I eat primal!
I got a slight pink that has not turned into a “hot” tan. I feel great and continue to be more energized then ever on 6-7 hours of sleep a night (was 8-8.5 before going primal).
Very good post Mark!
I would add that toxicity with daily oral intake at the 40,000 IU level, and that there are no reported cases of toxicity from sunlight exposure even though serum levels can be quite high among people who work outdoors:
http://healthcorrelator.blogspot.com/2010/02/vitamin-d-levels-sunlight-age-and.html
Hi Mark,
It may be worth pointing out that for some people, (depending on latitude), it may be impossible to make vitamin D via sunlight during the winter months. This article says above 37 degrees North or below 37 degrees South: http://www.mayoclinicproceedings.com/content/81/3/353.full
On the sunburn front, perhaps related to the dietary changes you mention, I have seen some articles that indicate that omega 3′s may be helpful: http://www.nature.com/jid/journal/v105/n4/abs/5610738a.html
Finally, the Vitamin D council website has some speculation that vitamin D itself may have a protective effect relative to sunburn, (you’ll need to scroll toward the bottom): http://www.vitamindcouncil.org/newsletter/even-more-vitamin-d-questions-and-answers.shtml
This is my first post so I hope the links work…
Hi Mark,
Just curious. You recommend 4000IU of vit D however your own damage control master formula only has 800IU. Is there any reason for this?
Good question there!