Vitamin D helps your body absorb calcium and keeps bones strong. Many people worry about low vitamin D, and supplements are widely sold, but more is not always better. This guide explains how much vitamin D you need, where it comes from, who is at risk of deficiency and what the safe upper limit is, using the NIH Office of Dietary Supplements consumer fact sheet.
How Much Vitamin D Do You Need?
The NIH gives these recommended daily amounts:
- Birth to 12 months: 10 mcg (400 IU)
- Children and teens 1 to 18 years: 15 mcg (600 IU)
- Adults 19 to 70 years: 15 mcg (600 IU)
- Adults 71 years and older: 20 mcg (800 IU)
- Pregnant and breastfeeding women: 15 mcg (600 IU)
Breastfed infants should get 10 mcg (400 IU) a day, usually from a supplement your pediatrician recommends.
Food and Other Sources of Vitamin D
Your skin also makes vitamin D when exposed to sunlight. How much you make depends on your skin tone, season, location and how much skin is exposed, so food and supplements matter for people who get little sun.
- Fatty fish such as trout, salmon, tuna and mackerel, and fish liver oils
- Fortified milk (about 3 mcg or 120 IU per cup in the United States) and fortified plant milks
- Fortified breakfast cereals, some juices and yogurts
- Beef liver, egg yolks and cheese in small amounts
- Mushrooms exposed to UV light
Signs and Effects of Vitamin D Deficiency
Severe, long-term deficiency causes rickets in children, where bones become soft, weak, deformed and painful. In teens and adults it causes osteomalacia, with bone pain and muscle weakness.
Doctors check a blood test called 25-hydroxyvitamin D. The NIH notes that a level of 50 nmol/L (20 ng/mL) or above is adequate for most people, and below 30 nmol/L (12 ng/mL) is too low for bone and overall health.
Who Is at Risk of Low Vitamin D?
- Breastfed infants who are not given a supplement
- Older adults
- People who rarely get sun exposure
- People with dark skin
- People with fat-absorption conditions such as Crohn disease, celiac disease or ulcerative colitis
- People with obesity or who have had gastric bypass surgery
Can You Take Too Much Vitamin D?
Yes. The upper limit for adults, teens and children aged 9 and older is 100 mcg (4,000 IU) a day from all sources. Very high blood levels (above 375 nmol/L or 150 ng/mL) can cause nausea, vomiting, muscle weakness, confusion, loss of appetite, dehydration, frequent urination and kidney stones, and extreme levels can damage the kidneys and heart rhythm.
The NIH says toxicity is almost always caused by too many supplements, not by food or sunshine. Avoid very high-dose tablets or sachets unless your doctor has prescribed them and is monitoring your levels.
Practical Tips
- Include fatty fish, eggs and fortified foods in your weekly diet
- Get safe, short periods of daytime sunlight where possible, without burning
- Ask your doctor before taking high-dose vitamin D, especially if you have kidney problems
- If you take a supplement, count the vitamin D from fortified foods too, so you stay below the upper limit
Helpful Video
Frequently Asked Questions
How much vitamin D should an adult take daily?
Adults aged 19 to 70 need 15 mcg (600 IU) a day, and adults 71 and older need 20 mcg (800 IU), according to the NIH.
What is a normal vitamin D level?
A blood level of 50 nmol/L (20 ng/mL) or higher is considered adequate for most people. Below 30 nmol/L (12 ng/mL) is too low.
Which foods contain vitamin D?
Fatty fish, fortified milk and cereals, egg yolks, cheese, beef liver and UV-exposed mushrooms are the main food sources.
Can sunlight cause vitamin D toxicity?
No. The NIH states that sunshine does not cause vitamin D toxicity. Excess levels come almost always from taking too many supplements.
What is the maximum safe vitamin D dose?
For adults and children aged 9 and older, the upper limit is 100 mcg (4,000 IU) a day from all sources, unless a doctor prescribes more.
Related reading: Iron Deficiency guide | Folic Acid and Folate guide
Sources
- NIH Office of Dietary Supplements: Vitamin D fact sheet for consumers
- NIH Office of Dietary Supplements: Calcium fact sheet for consumers
Medical disclaimer: this article is for general information and does not replace advice from a qualified doctor. Do not start, stop or change any supplement or medicine without medical advice.