How Often Should You Take Vitamin D?
Fact checked by Nick BlackmerMedically reviewed by Suzanne Fisher, RDFact checked by Nick BlackmerMedically reviewed by Suzanne Fisher, RD
Experts advise adults aged 19–70 to regularly take 15 micrograms (mcg), or 600 international units (IU), of vitamin D per day. The benefits of vitamin D, or the "sunshine vitamin," include supporting healthy bones and boosting immunity.
Debate has focused on the effects of large doses of vitamin D administered weekly rather than the traditional smaller daily dose. Too much vitamin D can lead to hypercalcemia, or dangerously high blood calcium levels. That's because the vitamin helps the body absorb calcium. A vitamin D deficiency, in contrast, can lead to bone pain and muscle weakness.
Most experts recommend smaller daily doses (outside of a few specific health circumstances). You can take either a vitamin D2 or D3 supplement, but D3 increases levels more than D2. Here's how to get vitamin D in your diet, what to look for in a vitamin D supplement, and how often you should take it.
Related: Health Benefits of Vitamin K
How Much Vitamin D Do Supplements Provide?
You'll find a wide variety of vitamin D dosages in pills, gummies, and other supplements. Many contain IU in the hundreds or thousands. One reason for the variation in dosages: A higher vitamin D dose administered weekly could result in some positive health outcomes for certain groups.
A review published in 2023 found that very high weekly dosages (up to 21,000 IU) reduced intensive care unit (ICU) hospitalization and death in people with COVID-19. Another study published in 2018 showed that pregnant people deficient in vitamin D3 received either 1,000 IU daily or 50,000 IU weekly. The group that received the high weekly dose had no adverse side effects and higher blood levels of vitamin D after 10 weeks.
There may be special circumstances where a higher weekly dosage is warranted, but most people who require vitamin D supplements need only a small daily dose. Those who are severely deficient in vitamin D might need a larger weekly dose for the short term.
Various factors contribute to finding the proper vitamin D dosage. The exact amount each person needs depends on where they live, their ethnicity, their underlying health conditions, and their specific symptoms.
Recommended Vitamin D Amount
The recommended amount of daily vitamin D for adults aged 19–70 is 15 mcg, or 600 IU. The tolerable upper limit (TUI), or the highest amount considered safe, for adults is 4,000 IU.
Vitamin D Deficiency
A surprisingly high percentage of Americans do not get enough vitamin D. A study published in 2022 found that about 41% of people in the U.S. have a vitamin D insufficiency, with the highest prevalence among those aged 20–29.
Vitamin D deficiency can show up with symptoms like fatigue, muscle weakness, and bone pain. You may sometimes not know you are deficient. A blood test is the only way to determine whether your vitamin D levels are low.
A healthcare provider may not recommend supplementation if your blood levels are sufficient, or 50 nanomoles per liter (nmol/L) or above. A regimen of daily vitamin D might be helpful for blood levels lower than that.
A healthcare provider may advise 600–800 IU of vitamin D per day for those who don't spend much time in the sun, take a daily multivitamin, or regularly eat foods fortified with vitamin D. Older adults and pregnant people may need more.
Vitamin D Excess
Consuming more than the TUI may lead to vitamin D toxicity. Vitamin D helps the body absorb calcium. Too much of the vitamin can lead to hypercalcemia, or dangerously high blood calcium levels.
Hypercalcemia symptoms include frequent urination, muscle weakness, nausea, and vomiting. Vitamin D toxicity may also lead to bone and kidney complications, including kidney stones.
Other Sources
Your body makes vitamin D in endless supplies from sun exposure, which is why many call it the "sunshine vitamin." Several foods naturally contain high amounts of vitamin D, while others can be fortified with the vitamin.
Foods With Vitamin D
There aren't many foods that have vitamin D. Some sources include:
Beef liver
Egg yolks
Fatty fish (e.g., mackerel, salmon, and tuna)
Fortified products (e.g., breakfast cereal, milk, and orange juice)
Sunlight
When exposed to the sun, your body makes vitamin D. It's important to practice sun safety when outdoors to prevent skin aging and skin cancer. Make sure you wear broad-spectrum, water-resistant sunscreen with an SPF of at least 30.
Considerations and Tips
Vitamin D is one of only four vitamins that require a source of fat for absorption. You can try taking vitamin D with a meal that contains some healthy fat, such as avocados and nuts.
Some people prefer to take a vitamin D supplement at a specific time of day, such as first thing in the morning or right before bed. The science isn't clear on whether this increases effectiveness. The best time of day to take your supplement is whatever time works best for you and helps you stick to a routine.
You'll have a vast array of supplements to choose from if you've decided to boost your vitamin D levels. This micronutrient is available in pills, chewables, liquids, and more. Some people even opt for vitamin D-enhancing sunlamps.
Look for a label that indicates third-party testing to choose a high-quality supplement. This means a supplement brand has allowed its product's contents to be verified by an outside organization. Third-party testing companies include NSF, USP, BSGC, and Informed-Sport. Seek out vitamins with their seal of approval.
Either vitamin D2 or D3 will increase your blood levels. Research has shown that D3 increases levels to a greater extent and maintains them longer than D2. You may also want to purchase a magnesium supplement. This mineral helps activate vitamin D.
Related: What To Know About Vitamin E Supplements
A Quick Review
The recommended amount of vitamin D to take daily for adults aged 19–70 is 15 micrograms (mcg), or 600 IU. You can get vitamin D in food and supplements, and your body naturally makes vitamin D when you're exposed to the sun. Food sources include beef liver, cheese, and fatty fish.
It's important to talk to a healthcare provider before starting a vitamin D supplement. They can test your blood levels to make sure you do not take too much.
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