# Vitamin D in dark winter months - supplements a good idea? Or woo? **URL:** \ **Category:** Factual Questions\ **Created:** [January 1, 2015, 10:02pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714 "2015-01-01T22:02:23Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![chiroptera](https://avatars.discourse-cdn.com/v4/letter/c/df705f/32.png) [@chiroptera](https://boards.straightdope.com/u/chiroptera)\ **Post date:** [January 1, 2015, 10:02pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/1 "2015-01-01T22:02:23Z")
That’s it, basically - information is all over the place online and I am not medically or scientifically savvy enough to understand the more complex medical literature. Even trying to stick with reputable (.edu, .gov) sources and filtering out Mercola, Readers Digest and general news stories, it’s confusing. I’m outside a _lot_, but we have long, often gloomy winters here. Earlier today I went on a 6 1/2 mile hike, but heavy cloud cover all day. We can go days without ever really seeing sun. I eat a fair amount of fish and eggs but from what I read, most diets don’t really provide enough vitamin D. Is it a good idea to supplement in winter? My dogs get fish oil capsules, would it hurt to take those? Pointless? Not a good idea, because it’s possible to over-supplement? A friend and I have been going around and around over this; she thinks it’s essential to supplement vit D in winter and is bombarding me with cites, and I just don’t know. 😕 ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [January 1, 2015, 10:14pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/2 "2015-01-01T22:14:40Z")
It can a help a lot and I know it does in my case because I have been tested for it a bunch of times. I was Vitamin D deficient for much of my adult life with moderate bouts of SAD and a few other symptoms to go along with it. Doctors picked up on it a few years ago when I was being tested for something largely unrelated and the suggested permanent Vitamin D supplements. I have taken them ever since (just cheap OTC versions) and they largely did away with the SAD and seems to make me healthier in general. My doctor recently compared some of my old blood tests with my new ones and specifically commented that my Vitamin D levels were finally stable and normal even during the winter. I don’t know if they are really needed for most people but most things I have read suggest they fall into the ‘Won’t hurt, may help’ category. You can get your own levels checked through a simple blood test if you and your doctor suspect you might be deficient some or all of the time. ---
**Author:** ![chiroptera](https://avatars.discourse-cdn.com/v4/letter/c/df705f/32.png) [@chiroptera](https://boards.straightdope.com/u/chiroptera)\ **Post date:** [January 1, 2015, 10:30pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/3 "2015-01-01T22:30:06Z")
Thanks **Shagnasty** , I didn’t think to ask my doctor when I went for my annual in October. I am thinking “won’t hurt, might help” as well but I was wondering about the current thinking on this. I know multivitamins have largely been debunked as long as one is of good health and eating a decent diet (as I am and do) and I sort of hate to buy into the supplement industry without good reason. AFAIK I don’t have any of the deficiency symptoms I read of - it’s the unseen symptoms (increased risk of cancer! Increased risk of cardiovascular disease!) I worry about more. Glad it worked for you though, depressive symptoms by any measure are not fun. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [January 1, 2015, 10:39pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/4 "2015-01-01T22:39:22Z")
Unknown. Low levels correlated with many things but little evidence of supplementation of a general population resulting in benefits. Good reviews [here](http://www.bmj.com/content/bmj/348/bmj.g2035.full.pdf) and [here](http://www.thelancet.com/journals/landia/article/PIIS2213-8587%2813%2970165-7/fulltext). > [@BMJ 4/2014](#): > > Conclusions Despite a few hundred systematic reviews and > meta-analyses, highly convincing evidence of a clear role of vitamin D > does not exist for any outcome, but associations with a selection of > outcomes are probable > [@Lancet 1/2014](#): > > Low serum concentrations of 25-hydroxyvitamin D (25[OH]D) have been associated with many non-skeletal disorders. However, whether low 25(OH)D is the cause or result of ill health is not known. … Results from intervention studies did not show an effect of vitamin D supplementation on disease occurrence, including colorectal cancer. In 34 intervention studies including 2805 individuals with mean 25(OH)D concentration lower than 50 nmol/L at baseline supplementation with 50 μg per day or more did not show better results. Supplementation in elderly people (mainly women) with 20 μg vitamin D per day seemed to slightly reduce all-cause mortality. The discrepancy between observational and intervention studies suggests that low 25(OH)D is a marker of ill health. Inflammatory processes involved in disease occurrence and clinical course would reduce 25(OH)D, which would explain why low vitamin D status is reported in a wide range of disorders. That said few harms have been identified either. A summary of[Vitamin D and depression](http://www.psychiatrictimes.com/depression/what-role-vitamin-d-depression): > [@](#): > > The evidence from observational studies showed a weak association between vitamin D deficiency and risk of depression. This association does not imply causation because it is not known whether vitamin D deficiency leads to depression or whether the reverse is true—depression causes vitamin D deficiency. To better understand the effect of vitamin D supplementation as a treatment option for depression, randomized controlled trials (RCTs) are needed. > > We recently looked at findings from 6 RCTs of vitamin D oral supplementation in depression.8 The majority (72%) of the 1203 study participants were women. Vitamin D was associated with improvement in depression symptoms after 8 weeks of supplementation only in the group with depressive disorder, not in adults at risk for depression (at risk was defined as individuals who were elderly, female, obese, or had vitamin D deficiency). > > A meta-analysis of the 6 RTCs showed no significant effect of vitamin D on depression symptoms. However, the quality of evidence in this review as assessed by the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool was low, and therefore better-designed RCTs are needed before a more precise estimate of vitamin D supplementation in depression can be reached. … I personally suspect the medical world embrace of Vitamin D supplementation (and it is embraced by many as almost everyone tested is “deficient” by current norms) will peak and calm down but for now it seems like most docs would endorse taking it on your same logic basis - little risk of harm and _might_ possibly help some slight amount. ---
**Author:** ![chiroptera](https://avatars.discourse-cdn.com/v4/letter/c/df705f/32.png) [@chiroptera](https://boards.straightdope.com/u/chiroptera)\ **Post date:** [January 1, 2015, 10:53pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/5 "2015-01-01T22:53:13Z")
Thank you **DSeid**. My first thought re: your second link was that depressed people tend not to get out and exercise, so that might be muddying the waters. I’m bipolar and when I’m in a down phase, even mediated with meds, getting out and exercising is a hard, hard thing to do. Even though I KNOW it will make me feel better. So I’m taking from this so far that at the very least, I may benefit by sharing the fish oil capsules with my dogs. 🙂 ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [January 1, 2015, 11:13pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/6 "2015-01-01T23:13:35Z")
The biggest potential problem with vitamin D supplements is that it’s a vitamin that can accumulate and be retained in the body and you might therefore reach harmful levels. (This doesn’t happen with sunlight-generated vitamin D - when the body gets enough it can just stop making it, as opposed to consuming already synthesized vitamin D). I’ve read some medical literature (peer reviewed type) indicating that even for the palest Caucasians it is possible to become vitamin D deficient in the winter months in the northern part of the US. Of course, a low D diet along with little sunlight will contribute mightily towards that - it sounds like you’re getting at least some in your diet and even on a cloudy day you get _some_ of the necessary daylight (though probably not enough). The _best_ way to go about this is to have your D levels actually tested and the supplement or not as indicated. As D is fat soluble and storable in the body it’s possible, if you get enough stored up in the summer time, eat well, and get some sunlight in winter you don’t need supplements. If you do choose to supplement without official testing be cautious about dosages and stay away from mega levels. ---
**Author:** ![chiroptera](https://avatars.discourse-cdn.com/v4/letter/c/df705f/32.png) [@chiroptera](https://boards.straightdope.com/u/chiroptera)\ **Post date:** [January 1, 2015, 11:30pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/7 "2015-01-01T23:30:31Z")
> [@Broomstick](#): > > The biggest potential problem with vitamin D supplements is that it’s a vitamin that can accumulate and be retained in the body and you might therefore reach harmful levels. (This doesn’t happen with sunlight-generated vitamin D - when the body gets enough it can just stop making it, as opposed to consuming already synthesized vitamin D). > > I’ve read some medical literature (peer reviewed type) indicating that even for the palest Caucasians it is possible to become vitamin D deficient in the winter months in the northern part of the US. Of course, a low D diet along with little sunlight will contribute mightily towards that - it sounds like you’re getting at least some in your diet and even on a cloudy day you get _some_ of the necessary daylight (though probably not enough). > > The _best_ way to go about this is to have your D levels actually tested and the supplement or not as indicated. As D is fat soluble and storable in the body it’s possible, if you get enough stored up in the summer time, eat well, and get some sunlight in winter you don’t need supplements. > > If you do choose to supplement without official testing be cautious about dosages and stay away from mega levels. Thanks. I’m a painting contractor, so in summer I am outside really a lot, working. And I know that D is stored in fat cells so part of my wondering is: how long do those stores last? Does it depend on one’s fat composition? That last because I am wondering about Inuit and Northern people, who I think have a higher percentage of body fat, which may be protective during very long dark winters (and may be mediated by a high fatty seafood diet.) And yea I am a pale and skinny Caucasian and I know that makes a difference. Although I don’t burn easily but tan well so I’m probably fine. I just want to point out here that I am not so much concerned about my personal well-being, as just wanting to know what the deal is in general. The friend who bugs me about needing more vit D is black, and I am just now realising that [vitamin D deficiency may be dependent on skin color](http://jn.nutrition.org/content/136/4/1126.full). I didn’t know that. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [January 1, 2015, 11:40pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/8 "2015-01-01T23:40:21Z")
> [@chiroptera](#): > > I just want to point out here that I am not so much concerned about my personal well-being, as just wanting to know what the deal is in general. The friend who bugs me about needing more vit D is black, and I am just now realising that [vitamin D deficiency may be dependent on skin color](http://jn.nutrition.org/content/136/4/1126.full). I didn’t know that. There is some science about that and even more armchair theories. The idea is that evolution selected for fairer skin as people moved out of Africa because it helped protect against Vitamin D deficiency in the more northern latitudes. This became the most extreme in places like Scandinavia where people with really white skin and blonde hair flourished (why do Inuits have black hair and darker skin then?). There are a lot of problems with this idea in general but it is not necessarily completely wrong either. A black person who lives in say Detroit, generally won’t produce enough Vitamin D at least during the winter months because their skin tone is the evolutionary result of a much sunnier and hotter environment. ---
**Author:** ![get\_lives](https://avatars.discourse-cdn.com/v4/letter/g/ecb155/32.png) [@get\_lives](https://boards.straightdope.com/u/get_lives)\ **Post date:** [January 1, 2015, 11:43pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/9 "2015-01-01T23:43:32Z")
It definitely reduces my dermatitis/dandruff and tooth plaque, as well as improving my sleep. I notice that the benefits actually start to reverse if I take too much. I recommend taking about 1000 IU daily for a couple of weeks, and see what that does for you. If nothing, stop taking it. Save this experiment for the winter months, to get the clearest results. IMHO, etc., IANAD, etc… ---
**Author:** ![Cat\_Whisperer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cat_whisperer/32/4839_2.png) [@Cat\_Whisperer](https://boards.straightdope.com/u/Cat_Whisperer)\ **Post date:** [January 2, 2015, 12:02am UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/10 "2015-01-02T00:02:09Z")
It’s not hard to get a blood vitamin D level - my doctor ordered one for me a couple of years ago, and I was indeed low. I take a small vitamin D supplement every day to make up for living at such a northern latitude. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [January 2, 2015, 12:51am UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/11 "2015-01-02T00:51:19Z")
> [@chiroptera](#): > > Thanks. I’m a painting contractor, so in summer I am outside really a lot, working. And I know that D is stored in fat cells so part of my wondering is: how long do those stores last? Does it depend on one’s fat composition? That last because I am wondering about Inuit and Northern people, who I think have a higher percentage of body fat, which may be protective during very long dark winters (and may be mediated by a high fatty seafood diet.) For the Inuit, at least, their historically traditional diet was _very_ high in D due to consuming a lot of seafood or predators of seafood (like seals). That may also be why, despite living in the far north many generations the Inuit are still relatively dark skinned. They were getting so much D in their diet there was no selective pressure for pale skin that makes more D. Probably a good thing, too - I don’t think the body is efficient enough at storing D to maintain adequate levels where winter nights can be weeks or even a couple months long. Northern Caucasians also historically tended to eat a lot of seafood, too. > [@](#): > > I just want to point out here that I am not so much concerned about my personal well-being, as just wanting to know what the deal is in general. The friend who bugs me about needing more vit D is black, and I am just now realising that [vitamin D deficiency may be dependent on skin color](http://jn.nutrition.org/content/136/4/1126.full). I didn’t know that. It’s _definitely_ related to skin color. People with dark skin in high latitudes are nearly always D deficient during the dark part of the year. Historically, dark skinned (black) people in the US have had higher rates of things like rickets, which is definitely linked to insufficient D. That’s one reason why milk is so often D fortified in the US, to prevent such diseases linked to low D levels. Unfortunately, a lot of dark skinned people are also lactose intolerant. People are resilient - the body can get by on low D levels temporarily. It’s just not good over the long term. ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [January 2, 2015, 1:24am UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/12 "2015-01-02T01:24:29Z")
> [@Broomstick](#): > > The biggest potential problem with vitamin D supplements is that it’s a vitamin that can accumulate and be retained in the body and you might therefore reach harmful levels. Very true. Hilariously (sorry, I just can’t stop laughing about it), alt med guru Gary “Death By Medicine” Null [managed to seriously OD](http://scienceblogs.com/insolence/2010/04/29/too-deliciously-ironic-for-words-gary-nu/) _on his own_ vitamin D-overloaded “Ultimate Power Meal” supplement. The ability of the body to store and accumulate vitamin D means that if you eat a healthy diet (beyond fatty fish and eggs, there are a number of foods (milk and organic juice) that are generally [fortified with vitamin D](http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/)) and get outdoors during the warmer months, you can get by nicely in wintertime even with less D intake. By the way, a task force [recently recommended _against_ routine screening](http://www.medpagetoday.com/Endocrinology/GeneralEndocrinology/48802) for vitamin D levels, noting the lack of consensus for defining normal/optimum values, and uncertainty about how those levels relate to health. ---
**Author:** ![chiroptera](https://avatars.discourse-cdn.com/v4/letter/c/df705f/32.png) [@chiroptera](https://boards.straightdope.com/u/chiroptera)\ **Post date:** [January 2, 2015, 2:13am UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/13 "2015-01-02T02:13:43Z")
> [@Jackmannii](#): > > Very true. Hilariously (sorry, I just can’t stop laughing about it), alt med guru Gary “Death By Medicine” Null [managed to seriously OD](http://scienceblogs.com/insolence/2010/04/29/too-deliciously-ironic-for-words-gary-nu/) _on his own_ vitamin D-overloaded “Ultimate Power Meal” supplement. > > The ability of the body to store and accumulate vitamin D means that if you eat a healthy diet (beyond fatty fish and eggs, there are a number of foods (milk and organic juice) that are generally [fortified with vitamin D](http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/)) and get outdoors during the warmer months, you can get by nicely in wintertime even with less D intake. > > By the way, a task force [recently recommended _against_ routine screening](http://www.medpagetoday.com/Endocrinology/GeneralEndocrinology/48802) for vitamin D levels, noting the lack of consensus for defining normal/optimum values, and uncertainty about how those levels relate to health. Welp, see yours and Jackmannii’s and other posts illustrate exactly why the waters are so muddied. What to believe? Everyone seems to make perfect sense, so right now I am leaning towards at least minimal supplementing with vitamin D in winter. Since I am not outside, eating seal and whale meat, for much of the winter. ---
**Author:** ![get\_lives](https://avatars.discourse-cdn.com/v4/letter/g/ecb155/32.png) [@get\_lives](https://boards.straightdope.com/u/get_lives)\ **Post date:** [January 2, 2015, 2:33am UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/14 "2015-01-02T02:33:52Z")
> [@chiroptera](#): > > Welp, see yours and Jackmannii’s and other posts illustrate exactly why the waters are so muddied. What to believe? Everyone seems to make perfect sense, so right now I am leaning towards at least minimal supplementing with vitamin D in winter. Since I am not outside, eating seal and whale meat, for much of the winter. Try my suggestion of taking 1000 IU daily for a few days or weeks to see if you can detect a difference. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [January 2, 2015, 2:55am UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/15 "2015-01-02T02:55:20Z")
Don’t worry too much. As **Jackmanni** ’s link notes it is very difficult to OD on D. Null was taking 2 million IU a day. _That_’ll do ya. A thousand or two a day will do you no harm. ---
**Author:** ![get\_lives](https://avatars.discourse-cdn.com/v4/letter/g/ecb155/32.png) [@get\_lives](https://boards.straightdope.com/u/get_lives)\ **Post date:** [January 2, 2015, 4:10am UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/16 "2015-01-02T04:10:24Z")
2 million is inSANE. I’ve had negative symptoms crop up at 10k daily. Granted, I was eating a high-fat, low-carb diet, which increases the effect of vit D, but still. ---
**Author:** ![actualliberalnotoneofthose](https://avatars.discourse-cdn.com/v4/letter/a/e79b87/32.png) [@actualliberalnotoneofthose](https://boards.straightdope.com/u/actualliberalnotoneofthose)\ **Post date:** [January 2, 2015, 7:15am UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/17 "2015-01-02T07:15:52Z")
> [@get\_lives](#): > > 2 million is inSANE. I’ve had negative symptoms crop up at 10k daily. Granted, I was eating a high-fat, low-carb diet, which increases the effect of vit D, but still. What are the negative symptoms? Just curious, as I’ve been taking 5k-10k daily and thought I noticed positives at 5k, but maybe not so much at 10. ---
**Author:** ![chiroptera](https://avatars.discourse-cdn.com/v4/letter/c/df705f/32.png) [@chiroptera](https://boards.straightdope.com/u/chiroptera)\ **Post date:** [January 2, 2015, 12:24pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/18 "2015-01-02T12:24:13Z")
Here’s the wikipedia take on [Hypervitamanosis D](http://en.wikipedia.org/wiki/Hypervitaminosis_D). Looks like it takes megadosing over a sustained period of time to really start having serious symptoms. I guess my friend is correct, certainly in her case because she has darker skin than I do. I’m going to start taking it, at least for the rest of winter. ---
**Author:** ![get\_lives](https://avatars.discourse-cdn.com/v4/letter/g/ecb155/32.png) [@get\_lives](https://boards.straightdope.com/u/get_lives)\ **Post date:** [January 2, 2015, 4:57pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/19 "2015-01-02T16:57:15Z")
> [@actualliberalnotoneofthose](#): > > What are the negative symptoms? > Just curious, as I’ve been taking 5k-10k daily and thought I noticed positives at 5k, but maybe not so much at 10. Mainly nausea for me, plus the return of symptoms that lower doses had lessened (tooth sensitivity, insomnia, dermatitis, etc.). ---
**Author:** ![EmAnJ](https://avatars.discourse-cdn.com/v4/letter/e/d2c977/32.png) [@EmAnJ](https://boards.straightdope.com/u/EmAnJ)\ **Post date:** [January 2, 2015, 6:08pm UTC](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714/20 "2015-01-02T18:08:25Z")
I take about 10K IU most days at the recommendation of both my primary GP and my fertility doctor (low Vitamin D has been linked to some types of infertility). I also live in a Northern climate. My levels have always been on the low end of normal unless I’m supplementing. I haven’t had any ill effects, but have also not noticed any significant benefits. [Next page](https://boards.straightdope.com/t/vitamin-d-in-dark-winter-months-supplements-a-good-idea-or-woo/708714.md?page=2)