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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 read more.

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.

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