You Should Be Taking Vitamin D Supplements

by | Dec 10, 2008
Vitamin D

Vitamin D

For the past several years the data in support of increasing vitamin D intake for every living human has been mounting. This week the American Journal of Clinical Nutrition features a collection of new research articles addressing the trends in vitamin D status and optimal dose recommendations.

This week’s take home lesson: While current research indicates we should be getting more vitamin D than is presently recommended, as a whole our vitamin D levels appear to have decreased in the past 15 years. The best way to combat this deficiency is with vitamin D supplements.

Vitamin D is a fat-soluble prohormone and essential nutrient produced when ultraviolet radiation (UVB) contacts our skin. It is probably best known for its role in bone metabolism (it has been shown to be more important than calcium for maintaining bone health), however recent studies indicate that vitamin D is essential for other physiological process as well.

Low blood levels of vitamin D have now been associated with many different chronic diseases including cancer, coronary heart disease, multiple sclerosis, Alzheimer’s disease, tuberculosis, depression, hypertension, periodontal disease, schizophrenia, seasonal affective disorder and type 1 diabetes.

In light of these findings, many nutrition researchers have argued for increasing recommended levels of vitamin D intake, but making population-wide recommendations have proved difficult for world health agencies because of large variability and uncertainty in vitamin D requirements.

There are several things to consider when evaluating vitamin D status in an individual. Latitude (sun exposure) is probably the single best predictor of vitamin D status. Anyone living in San Francisco or further north cannot get enough sun exposure to achieve sufficient vitamin D status, particularly during the winter months.

Because vitamin D is fat-soluble, it is retained in body tissues for several months after sun exposure. For this reason, people living at far north latitudes are particularly vulnerable to vitamin D deficiency because they frequently do not store up sufficient vitamin D during the summer to sustain their needs during the winter.

To further complicate matters, it is incredibly difficult to obtain vitamin D through dietary sources. Fatty fish and eggs are the only natural sources of vitamin D, though they are probably insufficient to achieve optimal status. Milk and soy products are typically fortified with vitamin D, as are some juices.

Skin pigmentation, sun avoidance and body composition (high body fat) are all associated with vitamin D deficiency. Darker skin tones do not convert sunlight to vitamin D as easily as lighter skin tones. Sunscreen blocks virtually all vitamin D synthesis. Body fat reduces bioavailability of vitamin D tissue stores.

This week’s study by Anne Looker et al, suggests that increased body mass as well as awareness of skin cancer risk and use of sunscreen have contributed to a significant decline in vitamin D levels in north America in the past decade.

The good news is that supplementation does appear to be effective at improving vitamin D status. Though there is still some disagreement on what the optimum blood levels of vitamin D are, it is generally agreed that they are much higher than currently recommended by any world health organization. One of the principle motivations of the present studies is to inform new vitamin D recommendations.

Kevin Cashman et al offers estimations of dietary requirements of vitamin D for healthy adults. They performed a randomized, placebo-controlled study testing the effects of different vitamin D doses and how they effect blood vitamin D levels.

The absolute minimum amount of vitamin D supplementation recommended by the study is 8.7 ug/day, or approximately 400 IU. This was to maintain blood serum levels greater than 25 nmol/L, and is double the current FDA recommendation for people under age 50. However, this suggestion is only sufficient to avoid deficiencies associated with bone loss and not other chronic diseases.

“The data from the present study clearly show that vitamin D tissue stores, developed during summer via exposure of skin to sunshine, were not sufficient to maintain serum 25(OH)D concentrations of greater than 25 nmol/L in most of the population [during winter], and that dietary vitamin D is an absolute requirement to maintain status above this minimum threshold.”

But the recommendations do not stop here. To maintain blood serum levels of greater than 50 nmol/L–a range more consistent with lowering risk of chronic disease–the study recommends 28 ug/day or 1100 IU of vitamin D. To keep blood serum above 80 nmol/L (from all I have read this is what I would recommend), 41 ug/day or 1650 IU is needed.

Remember this is most important if you are overweight, live north of San Francisco, get little sun exposure or have darker skin. Very rarely do I recommend vitamin supplements (they are not usually effective and are sometimes dangerous), but in this case the evidence is unequivocal.

Vitamin D supplements are easier to find than in the past, but they are usually packaged with calcium and are insufficient in dosage. Men should be wary of excess calcium supplementation since it is associated with an increased risk of prostate cancer.

I will continue looking for a good vitamin D supplement and will post when I find one I am happy with. If you have any recommendations, please share them with us.

Look for supplements where vitamin D is in the form of cholecalciferol, or vitamin D3.

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17 Responses to “You Should Be Taking Vitamin D Supplements”

  1. Mike says:

    I would think that being overweight would cause decreased deficiency for the following reasons:1. More body mass= more surface area to catch the sun’s rays! Sounds like a good reason to put on some holiday weight to me, and endorsed by Darya….2. Increased Fat stores allows for increased storage volume of Vit. D. If there is more fat, and Vit. D is fat soluble, wouldn’t the body be able to store a larger volume of the vitamin?I hope you do a follow up article giving recommendations about how we are supposed to go get all this newly necessary Vitamin D. I don’t really wanna take a pill- how many glasses of milk do I need to drink each day? Does all dairy have Vit. D? If just face/arms are exposed, how long do I need to stay in the sun? Does a tanning booth work?

  2. Anonymous says:

    I’m really curious about the evolution of research on Vitamin D. How come we only find out now, at the end of 2008 that it is so essential and can only be properly obtained through supplements? What was the research saying 5 years ago? 10 years?

  3. Darya Pino says:

    @Mike:It is not known why extra body fat decreases vitamin D status, but the working hypothesis is that it decreases bioavailability (not storage) of vitamin D.As you observed, the increase in fat mass should result in more tissue “storage volume.” However, this may translate to more of the vitamin getting bound up in fat and not available for mobilization into the blood stream for other purposes.This is just a hypothesis.—–@anon:The way most vitamins were discovered was by the observation that they prevent a specific disease. For example, scurvy is caused by vitamin C deficiency, so vitamin C is considered an essential nutrient (aka vitamin).Likewise, vitamin D was discovered to be essential to prevent rickets in childhood. Thus the optimal dose of vitamin D was considered to be the amount that prevented rickets.Only recently has the discovery of antioxidants to fight inflammation and chronic disease become apparent. Many vitamins (e.g., A, C, E, D) are also antioxidants and their additional functions and benefits to the human body are slowly being uncovered.In the past people did not live long enough to worry about things like cancer and heart disease. Only now is the importance of nutrition status being demonstrated in these chronic diseases.

  4. Jed Wolpaw says:

    Any reason you know of NOT to take 2000 IU per day?

  5. Darya Pino says:

    @jedGreat question! From what I have read there are few, if any, contraindications for vitamin D. Ubermega doses can cause soft tissue calcification, and some people have reported digestive issues (that were probably caused by the calcium that was included in the mega dose). Most studies show no problems whatsoever with doses in the 2000 IU range

  6. Matt Shook says:

    I take 2000 IU of D-3, along with a 400 IU of D with Ca (1000 mg)and Mg (500 mg) daily. It make such a difference…especially for those in colder/shadier climates like the Pacific Northwest where the sun disappears for weeks at a time.The other supplements that I have found to be phenomenal and essential (at least for vegetarians/vegans) are Coenzyme B-complex (derived from methylcobalamin, not cyanocobalamin) and astaxanthin (derived from algae). The latter has really helped me overcome general body soreness from commuting to work by bike everyday. I noticed a big difference when I stopped taking it for three weeks.

  7. Healthyliving says:

    Alright Darya, so my multivitamin has 400 IU of cholecalciferol which says 100% of RDA. It is trader joe’s brand. Is that enough? Do you think it is even absorbed?

  8. Jenny says:

    I have been taking Vitamin D which is contained in a cod liver oil supplement that I bought online from Goldshield and it has been great in reducing the pain in my wrists which have been giving me discomfort for many years. If I increased the dose would it result in a beneficial or negative impact?

  9. Darya Pino says:

    @HealthylivingThat dosage is on the low end, but it may be enough if you are getting plenty of sunshine and eating lots of fatty fish like salmon and sardines. Keep munching those Lily eggs too!—–@JennyCod liver oil is great. I kind of doubt you need to increase the dosage, but you can have your vitamin D levels measured to be sure (I think). Getting too much extra oil may cause some digestive problems, so be sure to increase doses slowly if you do. You should always check with your doctor before making any big decisions like that.

  10. StephG says:

    i take 2000IU vitD daily under my doctor’s recommendation. it helps quite a bit in managing depression. 1000IU wasn’t enough to maintain an optimal blood level. i’m relatively small–5’4″ 117lbs, fairly muscular and i live in the northeastern US. according to my dr, the rda for vitamins has typically been determined by taking a random cross section of the population (which is not necessarily a healthy cross section) and figuring the average level range. this may account, in part, for why the suggested level has been so low. Whole Foods offers a good 1000IU vitaminD3 supplement in softgel form (what i take now). they do contain gelatin which can be an issue for the strict vegetarian. btw, great post.

  11. Darya Pino says:

    @JennyI actually just read in the Berkeley Wellness letter that cod liver oil has so much vitamin A that it can leech calcium from the bones. You may look for a regular vitamin D supplement instead. I just bought the supplement from Whole Foods recommended by StephG. It looks virtually perfect to me.—–@StephGGreat recommendation! I just bought the 1000IU from Whole Foods. It has everything I am looking for in a vitamin D supplement 🙂

  12. Eboni says:

    Yes… I’m taking multivitamins from eVitamins.

  13. Scott says:

    I heard that excess vitamin D can cause a kidney stone. True? I heard from the same source that a kidney stone is more painful than going through childbirth- neither of which I want to experience. I’m not going to get a kidney stone by taking the TJs 1000IU Vit D supplement am I?

  14. Caroline says:


    My local healthfood store recommended I take 5,000IUs of Vitamin D. Is that too high?

  15. jay says:

    Doc said I have low d. Need to take 50,000 every week for 6weeks. Prescription d makes me feel sick….lightheaded and confused. Other d brands before this deficiency was discovered did the same thing. Should I be involving more calcium? Magnesium doesn’t help. Sublingual d doesn’t either. Its been 3 weeks and I don’t feel any better.
    It took many Er visits and tests in the past 4yrs to only find out I’m d deficient. Nothing else is wrong. I gained a lot of weight in that time too no matter how much I exercised. I’m now questioning my calcium intake.

    • Darya Rose says:

      50,000 IU is WAY too much, no wonder you’re feeling sick. Mine was low and I now take 2,000 IU in the summer and 4,000 IU in winter, and it corrected my deficiency quickly. Be careful, it is definitely possible to OD on vitamin D.

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