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A Doctor Answers Question on Vitamin D Recommended Daily Intake (RDI)

DrSugar Answers: Vitamin D Dosage?

DrSugar is in the house, and she's answering your health related questions.

Dear Doc Sugar,
I have heard from multiple sources (my kids’ pediatrician, an osteopath, an acupuncturist, etc.) about the importance of taking a vitamin D supplement. Coming from multiple sources has convinced me to start taking a supplement, but I am confused about how much to take. I just read from a Dr. Weil newsletter to take 2,000 IU of vitamin D daily, but other sources recommended 1,000 IU, and I have also read that the recommend amount is as little as 200 IU. So I am confused about how much to take. Can you tell me the proper daily dosage?
— Vitamin Popper

This is a fantastic question to discuss, as there is much debate even in the medical literature about what the adequate daily intake of vitamin D should be. Thus, you are not alone in your confusion regarding the proper daily requirement of vitamin D for adults! Read my answer when you


First, some background information on vitamin D. The primary function of vitamin D is to maintain normal blood levels of calcium and phosphorus. Vitamin D aids in the absorption of calcium, which helps to form and maintain strong bones. Recently, research also suggests vitamin D may provide protection from osteoporosis, hypertension (high blood pressure), cancer, and several autoimmune diseases. Therefore, the advice given to you about the importance of vitamin D was correct!


Very few foods in nature contain vitamin D. Fish, such as salmon, tuna, and mackerel, is a good source of the vitamin and small amounts are found in eggs and fish liver oils. Fortified foods such as milk and some brands of orange juice and yogurt provide most of the vitamin D in the American diet. The sun also contributes significantly to the production of vitamin D. According to the National Institutes of Health, most people meet their vitamin D needs through exposure to sunlight. But they also advise that despite the importance of the sun to vitamin D synthesis, it is prudent to limit the exposure of skin to sunlight and UV radiation from tanning beds.

Adequate daily intake levels have been established by the US Institute of Medicine of the National Academy of Sciences. Recommendations for all adult individuals under the age of 50 including males, females, and pregnant women are 200 IU (International Units) daily. Some researchers have questioned whether the current recommended adequate levels are sufficient, particularly for individuals deprived of regular sun exposure.The upper limit of vitamin D has been recommended at 2,000 IU daily due to toxicities that can occur when taken in higher doses.

Obtaining sufficient vitamin D from natural food sources alone can be difficult. For most people, consuming vitamin D-fortified foods and being exposed to sunlight are essential for maintaining a healthy vitamin D status. Additionally, dietary supplements might be required to meet the daily need for vitamin D.

As detailed above, there is a range of acceptable daily intake of vitamin D, and adjusting your diet, sunlight exposure, and supplementation to fall within that range is the best idea. But, if you are at all concerned about vitamin D supplementation, talk to your primary care doctor regarding what dosage is right for you.

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DrSugar's posts are for informational purposes only and should not be considered medical advice, diagnosis, or treatment recommendations. Click here for more details.

Join The Conversation
Living in Alberta in the wintertime I take at least 1500 iu a day of vitamin D. Vit. D is FABulous!!
clearskies clearskies 7 years
Very interesting. I work night shift so my mom sent me a vitamin D3 supplement with 2500 IU in it. I was kind of worried because the daily recommendation was so much lower than this.
MsSardines MsSardines 7 years
A story in the Financial Times (10-23-09) explains that the FDA’s recommendations are based a flawed 1984 study. Participants were supposedly given 3,800 IU of D but much later it was found that the daily dose was actually about 100 times that amount! Of course the participants got symptoms of overdose, such as kidney stones, vomiting and muscle atrophy. This mistake wasn't discovered for years. In the meantime, the FDA dropped the RDA from 400 IU to 200, and doctors have been paranoid about D ever since. Common sense should have revealed this mistake sooner because a pale person sunbathing midday in the summer for just 20 minutes makes at least 10,000 IU of vitamin D -- which is 50 times the RDA of 200 IU. This one mistaken study has had ripple effects that have undoubtedly caused tens of thousands of premature births, heart attacks, cancer deaths, and strokes. Just one example: over half the annual cost of heart attacks – that’s the medical care plus the lost productivity -- can be blamed on D deficiency, and that comes to $84 billion. Which is good, if you own stock in Big Pharma, but bad in every other way. Seven out of ten American kids are below optimum levels of D, and it's a similar number for adults. We don't have pellagra anymore because food was fortified with B vitamins. But the current idea that drinking D-fortified milk, which can provide that 200 IU of D a day, will be enough is clearly wrong. Canadian obstetricians advise pregnant women to take 2000 IU a day, 10 times what pregnant American women get from their prenatal supplements. No wonder the rate of Cesareans keeps rising (new research shows the lower the blood level of D, the higher the chance of a Cesarean). Another site that has D info is (upper left corner), including an article on how D protects us from flu.
Giasbash6260 Giasbash6260 7 years
I take 10,000 IUs of Vitamin D3 via supplement and I am sure I take in at least another 2 to 3,000 IUs from the foods I eat... IE: Salmon (in large quanties), Mackerel, Tuna & Sardines! I recommend everyone take vitamin D!
Spectra Spectra 7 years
I live in Wisconsin and I know I don't get enough sunlight naturally to get all my vitamin D. I take a supplement and I try to get some sun every day.
michlny michlny 7 years
Welcome back Dr. Sugar - we missed you!
mamasitamalita mamasitamalita 7 years
great info!
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