Wednesday, November 02, 2011

Vitamin D: More Observations on Sunlight vs. Supplements

There is solid scientific evidence that vitamin D improves immunity to respiratory infections and prevents cavities. Despite excellent dental care, I got a new cavity at least once every 3 years. At my worst after my kids started daycare, I caught cold after cold and was unwell for a whole year with either a cold or a secondary bacterial infection caused by a cold. In 2007 I learned that vitamin D might help me. I started with vitamin D supplements, 4000 IU/day, and soon began feeling better. Unfortunately, I soon experienced vitamin D side effects. Over the course of a year, I gradually switched from supplements to sunshine. Over the next two years I steadily increased my sun exposure in an effort to maximize vitamin D production. Starting about a year ago, to further increase vitamin D production, I started using a UVB lamp in addition to sun bathing.

Using the lamp made me nervous. It is an unnatural behavior. So I started reading up on using UVB lamps to produce vitamin D. To my surprise, despite spending hours looking for information and reading, I still don't know how much vitamin D I can make using UVB light from the lamp and the sun. Here's the best data I found, not surprisingly from John Cannell (The Vitamin D Council):

"Despite robust skin production, vitamin D toxicity
cannot occur from skin production. Once maximum
cutaneous production occurs, additional sun exposure will
not result in additional net input to the system. The same
UVB that produces vitamin D in the skin also degrades it,
causing a steady-state that generally limits cutaneous
production to a maximum of ∼ 20,000 IU/day. For this
reason, in spite of such robust cutaneous production, no
one has ever reported vitamin D toxicity from either sun
exposure or from exposure to artificial UVB light."

Cannell did not show any data to support his 20,000 IU/day number. I'm certain this number is based on a limited amount of data from a small number of racial groups. I was disappointed to read the "light therapy" page at Wikipedia and find no mention of vitamin D. I had to narrow my "light therapy" search at Google to "light therapy and vitamin D" to find much of anything at all. Medical science had the tools required to answer basic questions about vitamin D by at least the 1950's. Today's tools are fantastically superior and still the data has yet to be collected to answer basic questions about vitamin D. Even worse, some of the basic data we do have is being ignored.

Vitamin D supplements, even in low doses, cause side effects. Vitamin D made by skin exposure to sunlight does not cause side effects. I do not know why these facts are both true. Neither does anyone else. We are unlikely to get an answer until someone besides me recognizes these facts as facts. I could come up with at least a dozen plausible reasons. I can wait for the answer to emerge. Finding the answer is pretty far down my list of important questions about vitamin D waiting to be answered.

It really is difficult for me to understand why every physician and scientist isn't nervous about the safety of vitamin D supplements. Let's start with a quote from what I regard as the most authoritative study of vitamin safety. The book is called, "The Right Dose - How to Take Vitamins and Minerals Safely".

"You might say that an intake of 1,000 IU of vitamin D can be considered relatively untainted by current knowledge. The critical level for increased risk of heart attack, for instance, seemed to be 1,200 IU. In the study of kidney stones, the average intake was 1254 IU among those with no condition predisposing to stones. So an intake of up to 1,000 might seem like a safe bet. In fact, supplements containing 1,000 IU can be found easily. Count me out as one who will endorse this level of supplementation as a general measure. it lacks something that i spoke of only a chapter ago - a margin of safety."

Next consider the fact that pure vitamin D is acutely toxic. It is on the "particularly hazardous substances" list in the laboratory where I work. I can not purchase vitamin D or use it in the lab without special safety training. Extreme doses (the equivalent of a person taking millions of IU per day) are used as rat poison.

I want readers to know that I'm really struggling with the disconnect between the many published studies using 4,000 IU or higher doses of vitamin D that report no side effects and my own personal experience. I'm looking at a very small number of individuals, but every single person I know who took 4,000 IU or more of vitamin D per day stopped because of side effects. This information is supplemented by the outpouring of testimonials at my blog item titled "Overdosing on Vitamin D: Side Effects, Toxicity, Symptoms, Poisoning."

So here are the uncomfortable facts. Vitamin D is essential for good health. Supplement doses of >4000 IU/day are needed to elevate blood levels of vitamin D and to achieve obvious benefits. Supplement doses as low as 1000 IU/day are associated with serious health risks, and uncomfortable side effects are commonplace at daily doses at or above 4,000 IU.

Vitamin D supplements are amongst the oldest known supplements. The healing powers of fish oils, and cod liver oil in particular, have been exploited for centuries. Unlike the "Blue Zone" cultures, fish oil taking cultures are not known for exceptional health and longevity. These cultures did not land on vitamin D daily doses of 4,000 IU/day or higher - the amount now proven to be the minimum required for maximum benefit. A typical dose was closer to 1,000 IU. Vitamin D has been used for decades to treat osteoporosis. The calcium plus vitamin D supplements typically have 400 to 800 IU/day - not higher and not lower. Again, it is simply a fact that doses >4000 IU/day are required for optimum benefits. So why the much lower typical doses in the supplements used starting centuries ago and right up through the end of the 20th century? Side effects sure look to me like a logical explanation.

Unlike supplements, there is no evidence that vitamin D produced in the skin by exposure to sunlight or man-made UV light causes side effects or toxicity. Cultures of the world known for health and longevity all spend lots of time outdoors in the sun. Some of these cultures were recently reviewed in a book called "The Blue Zones". Responding to these facts, I stopped taking vitamin D supplements and started sun bathing and using a UVB lamp. I don't know how much vitamin D I can make this way, and if I did, I wouldn't know what it meant. I don't think it is safe to assume that vitamin D produced in the skin and taken as a supplement have the same potency.

I assumed that as I increased the amount of time I spent in the sun every day, that I would get more tan and therefore require more time to synthesize the same amount of vitamin D. For me, this assumption was wrong. Where I live, the UV index at noon varies from 3 at winter solstice to 10 at summer solstice. In the summer I found I could only stay out in the sun for 2 minutes on each side before I started to burn. So - I assumed that 4 minutes on a side at a UV index of 5 would initiate burning. It doesn't. I can stay out in the sun all day when the UV index is 5 without burning. When I figured this out, I started sun bathing multiple times on sunny days. Just a few minutes. Then I'd wait an hour or so and get another few minutes. I sometimes do this as many as 5 times. I don't get any side effects that I associate with sunburn. But I do feel like the increased sun exposure is changing me. I'm hesitant to characterize my sensations as side effects from sun and UV lamp exposure because they aren't severe and don't get worse and aren't entirely consistent. But I feel very different. That's why I was hoping to find information about the benefits and side effects of sunbathing and UV light exposure.

The UV light I use is sold as a "lizard lamp". The manual that came with the light instructs lizard owners to watch the behavior of their lizards. If they starting acting sick, then removing the lamp is recommended. The manual further instructs owners to make sure that the lizard always has access to shade so that the lizard can self dose on the light. If a lizard can "feel" the effects of UV light, why shouldn't I. Again, how can it be 2011 and I can't find any solid information to use to intelligently select a dosage of UV light to optimize the amount of vitamin D made in my skin?

The stakes are high. Since I started supplementing with vitamin D, my teeth have healed along with some serious joint pains. There is every reason to believe that vitamin D is responsible for these benefits. Almost a third of American adults suffer from osteoporosis, osteopenia, or hypertension. What if lack of UV exposure is the cause?

For me, the choice is an easy one. My teeth were in ruins and I was afraid to travel on an airplane because I would always hurt my ears and usually get a bad cold. Since I started with UV light, I've been getting steadily better. For those in good health, there is no easy decision. There are obvious risks from both UV light and vitamin D supplements. Cannell passionately believes that high doses of vitamin D will prevent a majority of cancer cases. If he's right, my risk of cancer is now much lower - a huge extra benefit on top of my improved immunity to colds and improved dental health. If I didn't have the bad teeth and poor immunity to colds, would I risk vitamin D side effects to prevent a cancer that I might not get in the first place? I don't know.

Any comments from readers? Can anyone point me to data about how the maximum amount of vitamin D that can be made by sun and UV light exposure? Please help if you can.


At 10:26 PM, Anonymous Anonymous said...

When you speak of vitamin d, are you referring to vitamin d2, d3, or a combination. I was told d3 was fine but to avoid d2.

At 1:33 PM, Anonymous moises said...

For more than a year, I have been using a UVB narrowband home device. I live in New York. Last February, my 25(OH)D was around 30. This was certainly lower than I expected. Perhaps if I had not been using the lamp my blood levels would have been even lower.
These lamps are very expensive. I don't think anyone would pay similar amounts of money for their lizards.

At the site there is a lot of general information about UVB lamps and specific information on their use to treat dermatological disorders.

My use of the lamp was to increase my vitamin d levels while avoiding any possible adverse effects from swallowing pills. I detected no obvious benefits. Likewise, I detected no side effects.

At 8:47 PM, Blogger Steve said...

Dear Anonymous,

I'm speaking of vitamin D3 - which is also made in the skin by UVB light.


At 9:02 PM, Blogger Steve said...


Fascinating. Thanks for the tip. The lizard lamp I selected is a broadband UVB lamp. I felt this was a better option compared to the narrowband - and cheaper too. I'm paying about $25.00 for a 160 watt lamp.

For whatever it is worth, after reading the science, I felt that measuring vitamin D blood levels was a waste of time. There is alot of variablility and not much data. I have been maximizing vitamin D, first with supplements and now by sunbathing and a lamp. I can't get more vitamin D without causing myself alot of discomfort. So what good does it do me to measure my vitamin D blood levels?

I strip down to my underwear and lie about 2 feet under the 160 watt bulb. I spend about 45 seconds on my back, then on one side, then on my stomach, and finally on the other side for 180 seconds total. Unlike you, I know I've been under the lamp. I don't want to characterize the feelings as side effects or benefits. I just feel like I was under the lamp. I feel that I've been obviously healthier. I felt obviously healthier from taking the pills, but had increasingly severe side effects. That's why I switched to sunbathing and recently sunbathing and the UVB lamp.

I'm glad we've connected here. How are you doing? I'm sorry you haven't found vitamin D to be more helpful. What, if anything, do you feel is helping?


At 12:17 PM, Anonymous moises said...

Thanks for your detailed reply.
As to what's been helping me? I wish I had more concrete advice. If I find something, I will certainly let you know. Thanks again.

At 10:44 AM, Blogger Bobber said...


I don't understand the concerns for toxicity you are expressing here. See for example:

At 10:46 AM, Blogger Bobber said...

Last weekend I felt a cold coming on. I took one 10,000 IU vit D gel cap along with extra magnesium, vitamin C and Niacin. No adverse effects that I can tell. I was able to nip the cold and am feeling great this week.

At 8:08 PM, Blogger Steve said...


Thanks for your comments and the link.

Here's a link:

In agreement with you, I blogged earlier that I formulated a concoction to ward off colds my kids called "the blast" 4000 IU vitamin D, 4000 mg vitamin C, and 250 mg time release niacin. It worked great. I'm glad you've landed on a similar formula and found it effective.

Returning to the source of my concern.

Typically cod liver oil doses landed near 1000 IU/day. So do calcium/vitamin D supplements. The British originally fortified milk at double today's levels. The higher level resulted in too many cases of toxicity. Unfortunately the lower levels have not completely eliminated Rickets.

I got hundreds of comments about bad side effects from doses of vitamin in the 4000 to 10,000 IU/day range. Finally, I've been continuously struggling with vitamin D side effects since I started supplementing 4 years ago. I've switched 100% to sunshine and haven't had any bad side effects, consistent with the apparently uncontested view that too much sunshine does not lead to vitamin D side effects. So there it is again.

I'm really glad to hear from you again. It's been a while.


At 9:48 AM, Blogger Bobber said...

Steve, My vitamin d routine has been the same for a couple of years now. During the summer months I take 2000 IU in the morning with breakfast and 2000 IU in the evening with supper. In the deep winter I add another 2000 IU for lunch. During the past year I have added magnesium since it appears to be a co-factor with vit D. Cannell describes vit D toxicity here:

I have not had any trouble with side effects during this time and I think my susceptibility to colds and flu has decreased significantly.

You said that you have developed a similar regimen but mine uses over twice as much vit D.

Not trying to be difficult at all here but just reporting my results which appear to be in accord with Dr. Cannell's observations.

At 6:54 AM, Blogger Steve said...


No difficulty at all! I love good news. You and I share a vulnerability to colds and the vitamins have been a godsend.

From your descriptions, I suspect I'm more susceptible to colds than you. So I am willing to max out on the vitamins and have intentionally kept increasing doses until I found my side effect limits. For vitamin D, I found this limit by taking 4000 IU vitamin D and just waiting. Sure enough, after 3 months the side effects came. I don't think the vitamin D has helped my immunity - I'm certain of it. And it has healed my teeth miraculously. My dentist is very uncomfortable around me now because I had a big fight with him the whole time my teeth healed. I told him my teeth were healing and it was the vitamin D and I was right - my teeth healed.

When I backed off vitamin D supplements, the side effects went away but the colds roared back. That's what got me going big time on the sunshine and now, sunshine and a UV lamp. I have not had intolerable side effects from the sunshine and lamp and am doing well fighting off colds.

No decisions in life are without risk. Unilke vitamin C, niacin, and thiamine, vitamins A and D can cause irreversible harm to the body. It is good to be more thoughtful about using these supplements. I'm certain the 4000 IU you're taking in the summer and 6000 IU/day in the winter are doing you alot more good than harm. I'm certain the UVB I'm getting is doing me more harm than good. I'm also certain that the UVB will age my skin faster, and that I'm raising my risk of skin cancers. So - there it is.

Thanks so much and keep sending me links to documents.


At 2:35 PM, Blogger Lili said...

Sorry this is not related to this post. I read your Niacin column and was wondering if you could please comment. My daughter was advised by a doctor to take Niacin for her symptoms of depression. She had a severe reaction to her 250mg dose. She is very petite, 83lbs., but she is 4'11", and 21yo. I don't think she will want to take it again, even knowing that this can be a normal reaction. I have been taking a high potency B vit. and folic acid combination and never had a reaction. Will it be as effective as taking Niacin directly?
Thank you for your blog and any advise would be greatly appreciated.

At 1:03 PM, Blogger Steve said...

Dear Lili,

Thanks so much for your question. It doesn't matter at all that it isn't related to the post.

Your daughter has much to gain, and little to lose by giving my advice a try.

Niacin alone is much less effective than niacin combined with vitamins D, C, A, and B1 (thiamine). The only safe way to gets lots of vitamin D is by sunbathing without sunburning. She should try to get into the sun in a bikini for 10 minutes every sunny day. She can go to a tanning salon anytime and ask for a tanning bed that simulates the sun for both tanning and vitamin D formation. Just one 10,000 IU vitamin A per week (yes per week) is plenty because the food supply is heavily spiked with vitamin A. She should try 1000 to 2000 mg of vitamin C three times per day (yes three times per day - vitamin C requires large doses to be effective). Then comes the niacin. Please don't let my advice scare you off. If what I'm recommending sounds too troublesome, I'll give you other alternatives. The best and safest way to take niacin is multiple small doses of pure niacin (not time release or slo release or any other kind of release). I recommend purchasing 100 mg tablets and cutting them into small pieces - try not to take more than 1/4 of a tablet (25 mg) at once. Carry around a bag of chips and just take one whenever you think about it. You can safely take a chip every 15 minutes. 250 mg/day is a great dose to shoot for so long as there are no side effects. If your daughter gets any side effects, she should just stop for the day. Side effects generally clear within hours using this very cautious approach. If your daughter can only take 100 mg/day niacin without side effects - that's fine - it's alot better than nothing and, in fact, be exactly what she needs.

I'm so sorry to hear about your daughter's troubles. I've had similar worries with my own children and it is alot of heartache. Please give my advice a try - there's much to gain and little to lose. And don't hesitate to ask more questions. I'm sure that I can convince you that my advice is remarkably safe.


At 6:03 AM, Anonymous PBM said...

Hi Steve, I have been reading your vitamin D overdose blog back in december 2008, I am wondering if you could provide updates of what happened to all those people? Or those who have updates at least, I fear that I may have a vitamin d overdose and i was wondering how long before it leaves my system for good! I really need the positivity right now,. its been a few months, I'm thinking its vitamin D since I just became WORSE after taking 4000 IU every day for 3 months, thank you so much...

At 4:31 AM, Anonymous asg said...

hi steve,

your blog has been very helpful for me. Can I ask if people have updated how they are after vitamin D overdose? I believe I may be one of them and I really would be greatful to know others who have gone through the same thing and beat it

At 6:09 AM, Blogger Steve said...

Dear ASG,

I've gotten a couple of comments that you may have read from people who were not back to normal after 3 to 6 months. If my own experience and the literature can be trusted, these cases are very rarely. Most people are functionally 100% after just a day or two. Just knowing that symptoms are a vitamin D side effect is often enough to reduce the symptoms to irrelevance.

Keep in mind that when you stop vitamin D and start lowering the amount in your body, the benefits of higher vitamin D levels will go away too. I depend on vitamin D to enable my immune system to fight off cold viruses. Recently I've been getting under a Fluker Farms lizard lamp twice every day - once when I wake up and a second time around noon. My health has been better and the side effects from the light therapy are minor and I'm optimistic that they are getting more minor.

If you're not feeling well, go see a doctor and get a full physical.

Good luck,


At 11:37 PM, Anonymous asg said...

Your Blog on vitamin D overdose with the 400 comments has been very helpful to me. I have been to numerous doctors and blood tests because I was feeling weak and felt tingling sensations and semi numbness on my hands. I have to admit that I have been skipping meals for around 3 months because of intense work. (editing on the computer for long hours) All my blood tests were fine except for vitamin D. I started supplementing 4000 IU and then from only 2 symptoms came ALOT more!! I developed super insomnia, slurred talking, headaches, malaise, twitching muscles, frequent urination it was crazy, burning eyes. I suffered 5 months and then read your blog, stopped supplementing, then just like that (about 2 weeks), I was able to sleep again, no more slurred speech, no more urinating 7 times a night. The worst was over hopefully. However, I am still a bit fatigued compared to my very active lifestyle before, and a bit of pressure on my eyes. I have improved but I guess I just miss my energetic self just a year ago. I hope in time my body fully recovers from this. My theory is I had weakness from skipping meals then just made things worse by supplementing vitamin D. I am not against vitamin D supplementation but I have read so many people complain about it and so many people praising it. I believe it is a GREY area in the medical world. So many factors such as the active ingredient in D, brand, Type of D d2 or d3 etc... mine was from wool oil, I heard people were allergic to it or lanolin etc.. but I can never be sure as long as doctors keep pushing their wonderful discovery about vitamin D. I am almost so mad that they would validate their claims without being 100% about it! Then again i think God is teaching me a lesson not to work so much to the degree that i would skip meals.
I thank you for your blog and work, you are a good man with a good heart.

At 3:50 PM, Blogger Steve said...

Dear ASG,

Thanks for your kind words. Thanks also for responding to my appeal and leaving yet more testimony for the physicians to ponder.

I recommend that you take your low vitamin D level seriously. I think there's much to gain and little to lose by giving sunshine a try.


At 2:30 AM, Anonymous Anonymous said...

Dear readers:

Why don't you better read or where a large community of doctors can answer all your questions about vitamin D. By the way, don't take Cod liver oil, it contains retinol which is a powerful antagonist of vitamin d and can cause very serious health problems. Scott's emulsion has been called "a poison" by Dr. Cannell. If you neet vitamin a, get it from beta carotene, not retinol. The people at vitamin d council and grassroots health are actual doctors from prestigious hospitals who can answer your questions.

At 8:32 PM, Blogger Steve said...

Dear Anonymous,

Thanks for your comment.

I also recommend that my readers visit and

I have. I'm endebted to both groups for educating me about the potential benefits of vitamin D.

No one can answer all questions about vitamin D because there is alot left to learn.

Vitamin D metabolism is complex. I personally have had trouble with vitamin D side effects - as have a large fraction of those whom have followed my advice to increase vitamin D levels.

I wish I knew more. For the moment, I've concluded that sunshine is safer than supplements, and have acted accordingly. ]

I'd like to be proven wrong, but the testimony that vitamin D supplements are often toxic just keeps on accumulating here. I don't see how that is going to change.

Thanks again for your comment,


At 3:54 AM, Anonymous asg said...

I actually got my levels up from 63nmol/L to 133 with supplements and sunshine. I don't know how to convert it to your standard units but 133 should be really good. However like I said, I can't ignore all the new symptoms and side effects the gel caps gave me.
It might have been the brand because the bottle said it was repacked from the united states. But I also can't ignore numerous comments on this blog and

Some people just took 1000iu because of the reported health benefits only to suffer side effects. We can't ignore this and just push say "well, it works for 70% of the people who take it, sorry for those who have adverse effects" that is not how doctors or medicine is supposed to be. It is very easy to shrug off those comments if you are not experiencing them yourselves.

At 10:07 PM, Blogger Steve said...

Dear ASG,

I didn't realize until today that we've been going back and forth for the past few comments. Thanks so much for interacting.

My experience was that as I switched to more and more sunshine, I became increasingly sensitive to vitamin D supplements (pills). I'm saying that I believe sun exposure reduced my tolerance for vitamin D supplements. I wrote a blog entry earlier on just this point. Did you have the same experience?

Thanks for the link to healthoma. Do you have any idea how that particular article attracted so many comments - and such a long time after the article was posted?

I haven't really paid much attention to vitamin D levels. I'm not persuaded that enough information is available to interpret the results - except when the result shows extreme deficiency. The units you quote - nmol/L, are the normal units. No need to convert.

There's just no question that the side effects showing up in these two comment strings are common. Vitamin D causes side effects. Vieth's claim that most people can tolerate 40,000 IU/day is incredible. I haven't met anyone who is able to maintain such a high dose for over a year.


At 11:21 PM, Anonymous asg said...

Hi Steve,

I think healthoma got those comments and even after a long time is because the top 2 sites that come up when you type "vitamin d overdose" is your blog and healthoma even if its been a post made years back.
Thats the first thing I typed after noticing why I felt better when I stopped supplementing.
Also, just a guess, is that people just started feeling side effects and looking for answers online after 2007 or 2009 when the "vitamin D hype" stared. The internet has been there for a long time and I never saw any person complain about side effects before at least 2007. Why is that? because doctors did not push it since then. I read a comment that in some areas, routine check ups now rewuired testing for vitamin D which was not part of the routine before. Now 2011, after the success of their advertising this vitamin, people have been complaining, even youtube!

Again I am not against vitamin D. I just really believe that people should be monitored by a professional, and that pharma companies shouldn't be allowed to sell over the counter thousan IUs. Or maybe scientists and doctors just better study it more.

At 2:16 AM, Blogger Dawn said...

I am one of the follow ups from the side effect blog on here. I went back to normal even though I still have a chronic illness. I still wondered if I could get away with smaller doses, I tried codliver oil, but even that made my arms ache after the first few doses so I stopped them. I then decided maybe D3 with K2 from Now foods might work by taking the vit d where it should go with the k2. I found myself getting more and more anxious over the last few months and thought it was my illness. I then over the last 4 months have been getting eye trouble again, prickling, burning, watering, needing drops to cool them from drying out. I was always at the toilet for a pee if you excuse the information too. Then I had to fast my supplements this last 2 weeks for a test I am having next week and blood tests will be involved. I now feel much calmer and the eyes are much better since the vitamin d is wearing off. So I wsan't tolerating it as well as I thought and the symptoms are so similar to what I originally wrote. I am housebound so I really don't know what I am going to do about getting vit d.
To whoever said write to the Vit D council, I have on a number of occasions about my side effects and need for it due to being housebound and they totally ignored me.
such is life. \i should win a lottery and buy a house in the sunshine, with a ladies maid to wheel me into the garden :d
hugs and good health to all

At 8:53 AM, Anonymous Anonymous said...

Steve you said:

I'm certain the UVB I'm getting is doing me more harm than good.

Please explain harm and why continue uvb.
Do you feel same about sunlight?


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