The half life seems to be 15 days and one study showed there was still some around 84 days after a 100k megadose.
Further, don’t underestimate the sun. Me, pale Dutch guy, once got sunburn after walking around outside in Madrid for an hour in January. That’s the same latitude as Philadelphia (40 degrees north).
Long ago this probably was less of a problem because if vitamin D is stored in fat cells during summer, then it should be released during winter as people lose weight because there’s less food.
I recently found myself sitting around talking with a group of learned individuals, two of whom were MDs. The two doctors were on extreme opposite sides of the Vitamin D fence. Just an observation.
My doctor prescribed for me 50,000 IU of Vitamin D once a week, which averages out to a little more than 7,000 per day. A few winters ago I experienced a bad case of S.A.D., and have been hoping every years that it doesn’t come back. I don’t get enough sunlight in the wintertime, but since I’ve been taking the D supplements, S.A.D. hasn’t attacked again.
My doctor said the same thing – and that wearing sunblock contributes to the problem. As one of the pale caucasians, I feel like I’m damned if you do…
I’m on my second go-round with prescription-level vitamin D treatment – but my level was tested and found to be pretty low. I’m fine with taking the RX treatment – it’s much better than feeling awful and achy and unhappy for months!
For non-prescription treatment, my doc said that 2,000 IUs daily is fine. You can even get them in gummy form, if you’re so inclined.
ETA – since taking the 50,000 IU/weekly treatment, my fingernails grew in stronger. Nice side effect.
GrumpyBunny, I got the gummy 2000 IU ones yesterday. Strawberry flavored.
My nails have always been ridiculously strong, but I tend to have less energy in winter (not SAD, I don’t believe) and I’m a female closer to 60 that 50 so it’s supposed to be good for bone strength.
My doc started screening for Vitamin D during annual physicals a few years ago, and because I am somewhat olive-skinned, live in a cold northern climate, don’t get outside enough, and tend to have my annual physicals in late winter, my levels are always low. 5,000 IU a day keeps me on the low end of normal. Since I started supplementing, I seem to get sick less, but I made other changes too (allergy meds daily, etc.) Osteoporosis runs on Mom’s side, so I’ll take all the help I can get, and vitamins are cheap and easy.
You might be interested in the thread under “Comments on Cecil’s Columns” on skin cancer. One point that comes out of that is that messaging sun protection as being very important while also messaging that some regular lower intensity exposure is good, whether we are concerned about vitamin D exclusively or not. Without having people feeling “damned if they do …”
As to the bit stated there that “prolonged sun exposure does not cause your vitamin D levels to increase further” the reasonis:
This bit from the same article is also interesting:
So low levels are not only a function of extremely little chronic/regular sun exposure and little exercise but also secondary to obesity. Easy to see why it may be a marker for all sorts of bad outcomes. No question that exercising and losing some excess fat over winter will help keep your vitamin D level up and help keep you healthy (even if not because your vitamin D level is up).
Maybe, possibly, some benefit to supplementing the general population (although it seems not); likely little harm. But the best approach is mild to moderate regular sun exposure when possible (not strong intermittent), regular exercise, avoiding obesity and losing some fat mass in particular over winter months. So those resolutions? Hop to it!
I take 50,000IU of D3 EVERY DAY in order to maintain a D level of around 40. I have short gut syndrome and absorb very little fat, and therefore very little of the fat-soluble vitamins A, D, E, and K. I can definitely feel the effects if I stop taking my supplements—I get achy bones and joints. I’m also concerned about bone health, because I malabsorb calcium as well. Adequate D is necessary to absorb calcium. I get my D levels and my PTH levels (an indicator as to whether I’m robbing calcium from my bones) checked every three months.
Over the years I’ve found that maintaining my D levels is much less difficult than raising them was in the beginning.
Why is everyone arguing about the value of vit ad supplementation? We’ve been fortifying the milk supply since, what, the 1940s? And since more and more people avoid dairy products, or at least fortified dairy, then moderate supplementation should not be controversial. LOL…where are all these naysayers when federal agencies are discussing fortification?
From** The Human Body** by Isaac Asimov (after he noted that Vitamin D, necessary for bone formation, can be produced in the skin by sunshine):
“Vitamin D is essential to to proper formation of bone [cross-reference], and since it is present in very few articles of diet, there was, before the 20th Century, constant danger of improper bone formation among children born at the start of the northern winter. The sun was almost the only agency by which the vitamin could be obtained.”
It sounds like you’re equating vitamin D supplementation with all other forms. That assumption might make it easy for knee-jerk skeptics to get a toehold in the conversation, but not all supplementation is equal. Do you need cites?
Sounds like you’re equating fortification such that RDA level is more likely hit with supplementation well over RDA. And not comprehending why past experiences give one caution.
RDA for vitamin D is currently 800 IU/d for most age groups. You would have to ingest 2 quarts of vitamin D fortified milk to get that. Most people taking supplements are taking much more than that and many are taking well over the 4000 IU/d that the Institute of Medicine states is a safe upper limit.
Past experiences have found that vitamin supplements (in particular supplementing above RDA levels) have been either unhelpful or, surprisingly, harmful, despite the fact that the same levels obtained by more natural sources (e.g. vitamin rich real foods) have been associated with excellent outcomes. Even folate, the poster child for the success of fortification (fortification has, for example, dramatically reduced the incidence of neural tube defects like spina bifida) may cause significantly increased risks for certain cancers even at daily multi supplementation levels. Some being good does not mean that more is better.
Vitamin D is so far following the same trajectory we’ve lived through with other vitamin supplementation stories: 1) We get too little. 2) Those who get more through natural sources (real foods in the case of other vitamins, mild regular/chronic, not strong intermittent, sun exposure especially coupled with exercise for vitamin D) have better outcomes on a variety measures. 3) “It couldn’t hurt.” 4) Widespread embrace of supplementation well above RDA levels 5) Studies then done that show supplementation does not result in the same benefits.
When #6 on that trajectory has in the past often been: “Ooops, not only are no benefits seen but it turns out there may be harms after all.” … Well a little bit of caution is not unreasonable.
Fair enough. However, people are going to vary in how well they process/store/use vitamins. An intake level cannot be reasonably determined for all people, even accounting for body mass and non-supplement consumption
I will also point out that some people taking supplements in this thread have been actually *tested *by actual doctors and found to have abnormally low levels of vitamin D in their bodies… a situation where supplementation is entirely appropriate.
For the general case get lives, a reasonable range of vitamin intake can be determined for the vast majority of people. Short of circumstances like MsBatt’s short gut syndrome most of us are built not too dissimilarly from each other.
Broomstick indeed. The comments I’ve made are regarding supplementing the general population, not those identified with insufficiencies or deficiencies, Jackmannii’s link to an article discussing the recent U.S. Preventive Services Task Force recommendation against routine screening notwithstanding.
Sorry for multi-posting but one other very interesting bit about vitamin D levels, this related to the frequency of identified vitamin D deficiency in American Blacks.
The answer according to the article turns out to be in differences in a circulating vitamin D binding protein but still the simple fact is that those who should be at the greatest risk for vitamin D deficiency by virtue of living in a relatively low irradiance geography while having dark complexion have the least problem as they age with the one health outcome most strongly related to vitamin D levels.
