Natural Health Products

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Vitamin D

General Information

Vitamin D comes from three sources: the sun, food (e.g., fish, milk, salmon), and dietary supplements. It is a fat-soluble vitamin, and it can accumulate in the body because it is stored in the liver and fat tissues for long periods of time. It improves the absorption of calcium, a mineral that helps build and maintain healthy bones. It also improves the absorption of phosphorus, a mineral that is important for the development of bones and teeth.

There are two forms of vitamin D that are important to people: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D2 comes from plants, while vitamin D3 is made in our skin when it is exposed to sunlight. Both forms of vitamin D can also be found in food.

Common Name(s)
vitamin D, vitamin D2, vitamin D3
Scientific Name(s)
1,25-dihydroxycholecalciferol, 25-hydroxycholecalciferol, alfacalcidol, calcifediol, calcipotriene, calcitriol, cholecalciferol, ergocalciferol, paricalcitol, vitamin D
How is this product usually used?

Vitamin D is generally taken by mouth. It is available in different forms, including chewable tablets and gummies, tablets, capsules, powders, strips, drops, and liquids.

Vitamin D is listed in both micrograms (µg) and international units (IU). 1 IU of vitamin D is the same as 0.025 µg of vitamin D2 or D3. Vitamin D in supplements is usually shown as IU. Table 1 lists the usual dose and the adequate intake (AI) levels for vitamin D for different age groups. People with vitamin D deficiency might need doses at or above the RDA.

Table 1. Usual daily dose and AI levels for vitamin D for different age groups.

Age group

Vitamin D (IU/day)


Usual dose range


0–12 months




1–3 years



4–8 years




9–13 years



14–18 years




19–50 years



51–70 years



≥70 years




14–50 years




14–50 years



Depending on your history or medical conditions, your doctor may recommend higher doses of vitamin D (for example, to help prevent/treat osteoporosis, 800 to 1000 IU of vitamin D is generally recommended).

Your health care provider may have recommended using this product in other ways. Contact a health care provider if you have questions.

What is this product used for?

Vitamin D is important in maintaining overall good health. It helps develop and maintain bones and teeth. It also helps the body absorb and use calcium and phosphorus. Vitamin D taken with calcium is also used to help reduce the risk of developing osteoporosis (a condition where your bones become weak, which increases the risk of fractures). Studies have consistently shown that 800 IU of vitamin D lowers the risk of fractures of the spine, hip, wrist, and leg in adults, which are all complications of osteoporosis.

At doses at or above the AI, vitamin D supplementation helps to prevent vitamin D deficiency.

Vitamin D has also been used to treat weak or soft and painful bones, low blood phosphate levels, low blood calcium levels, psoriasis, and rickets. It may also help prevent bone loss in people with chronic kidney failure and help prevent falls.

There is also research showing that a higher dose of vitamin D supplementation may lower the risk of certain types of cancer. There appears to be a link between low vitamin D levels and colorectal cancer. However, there is limited evidence of benefit in taking vitamin D supplements for breast cancer and no evidence of benefit for prostate cancer. More research is needed to determine the effects of vitamin D on cancer.

Your health care provider may have recommended this product for other conditions. Contact a health care provider if you have questions.

What else should I be aware of?

You should ask a health care professional for information on how much vitamin D you should take, as it may be different depending on your age and what you are using it for.

Vitamin D is generally well tolerated when taken in recommended doses. High doses of vitamin D over a long period of time can cause weakness, loss of appetite, weight loss, increased urination, irregular heart rhythms, dry mouth, drowsiness, headache, nausea, vomiting, and fatigue. Chronic vitamin D overload can increase blood calcium levels, which can subsequently harden the arteries and damage organs such as the heart and kidneys.

Medications that can interact with vitamin D supplements include:

Consult your health care provider if you have concerns.

Women who are pregnant or breast-feeding can safely take oral vitamin D supplements in recommended amounts (with a maximum of 4000 IU/day). Higher doses might harm the infant. It is safe for infants who are breast-fed to be given vitamin D supplements provided the total amount of vitamin D (from all sources) does not exceed the recommended dose.

Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.

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