How much vitamin D you need per day by age and sex

Short answer: Most people aged 1 to 70 need 15 mcg (600 IU) of vitamin D per day, rising to 20 mcg (800 IU) at age 71 and older, according to the NIH Office of Dietary Supplements. The tolerable upper limit from all sources combined is 100 mcg (4,000 IU) per day for anyone aged 9 and older, including during pregnancy and breastfeeding.

What vitamin D does in the body

Vitamin D has several well-established physiological roles. It promotes calcium absorption in the gut and helps maintain adequate levels of calcium and phosphate in the blood, which the body needs for normal bone mineralization. It also supports bone growth and bone remodeling carried out by osteoblasts and osteoclasts. Together with calcium, adequate vitamin D intake helps protect older adults from osteoporosis. A separate but related role is preventing hypocalcemic tetany, a condition involving involuntary muscle contractions, cramps, and spasms that can occur when blood calcium falls too low.

Daily targets by age and sex

The figures below are population reference values from the NIH Office of Dietary Supplements. They reflect the Recommended Dietary Allowance (RDA) or Adequate Intake (AI) for each group and cover total intake from food, beverages, and supplements combined. They are not personal prescriptions. Please consult a clinician or registered dietitian to determine the right amount for your individual situation.

Infants

• 0 to 12 months: 10 mcg (400 IU) per day (Adequate Intake)

Children

• 1 to 13 years: 15 mcg (600 IU) per day

Adolescents

• 14 to 18 years: 15 mcg (600 IU) per day

Adults (men and women)

• 19 to 70 years: 15 mcg (600 IU) per day
• 71 years and older: 20 mcg (800 IU) per day

Pregnancy and lactation

• All ages: 15 mcg (600 IU) per day

Sex does not change the recommended amount at any life stage. The increase at age 71 reflects the greater difficulty older adults have synthesizing vitamin D in the skin and absorbing it efficiently.

The upper limit and why it matters

The Tolerable Upper Intake Level (UL) is 100 mcg (4,000 IU) per day for everyone aged 9 and older, including during pregnancy and lactation. For children aged 1 to 8 the UL is lower; a pediatrician should guide dosing for young children. Staying within the UL matters because taking too much vitamin D from supplements can cause hypercalcemia, a condition in which blood calcium rises to harmful levels. Symptoms can include nausea, weakness, frequent urination, and in severe cases kidney damage. Food and sunlight alone are very unlikely to push anyone over the UL; the risk comes primarily from high-dose supplements taken without medical supervision. A health care provider may prescribe doses above the UL in specific clinical situations, but that decision belongs with a qualified clinician, not a general guide like this one.

What the research actually shows

Evidence for vitamin D's benefits varies considerably depending on the health outcome in question. Here is an honest summary graded the same way the NIH Office of Dietary Supplements grades it.

Strong evidence

• Vitamin D promotes intestinal calcium absorption and maintains the serum calcium and phosphate levels needed for normal bone mineralization.
• Vitamin D deficiency causes rickets in children and osteomalacia (soft bones) in adults.

Moderate evidence

• Vitamin D combined with calcium supplements can slightly increase bone mineral density in some postmenopausal women and older men, and may reduce fracture rates in institutionalized older people.

Limited evidence

• Vitamin D supplements may reduce falls or fractures in community-dwelling older adults, but the data are not consistent enough to draw firm conclusions.

Insufficient evidence

• Current research does not support the claim that vitamin D supplements prevent or treat cancer, cardiovascular disease, depression, multiple sclerosis, or type 2 diabetes, or that they aid weight loss. Studies have produced mixed or inconclusive results in all of these areas.

Vitamin D supplements are not intended to diagnose, treat, cure, or prevent any disease, and these statements have not been evaluated by the FDA.

Medications that interact with vitamin D

If you take any prescription or over-the-counter medication, talk to your doctor or pharmacist before adding a vitamin D supplement. The NIH Office of Dietary Supplements flags the following interactions.

• Orlistat (Xenical, alli): This weight-loss drug can reduce how much vitamin D your body absorbs from food and supplements.
• Statins (for example atorvastatin/Lipitor, lovastatin/Altoprev or Mevacor, simvastatin/FloLipid or Zocor): High-dose vitamin D supplements may reduce how well these cholesterol-lowering drugs work.
• Corticosteroids such as prednisone (Deltasone, Rayos, Sterapred): Long-term use can lower blood levels of vitamin D.
• Thiazide diuretics (for example chlorthalidone/Hygroton, indapamide/Lozol, hydrochlorothiazide/Microzide): Combining these with vitamin D supplements can raise blood calcium to an unsafe level.

Getting vitamin D from food and sunlight

Dietary sources include fatty fish such as salmon and tuna, fish liver oils, egg yolks, and foods fortified with vitamin D such as milk, some plant-based milks, and certain breakfast cereals. The skin also synthesizes vitamin D when exposed to ultraviolet B sunlight, though the amount produced depends on factors including skin tone, latitude, season, sunscreen use, and age. Because it is difficult to meet needs through diet alone for many people, a supplement is a practical option, but the same upper limit applies regardless of the source.

When to see a clinician

A simple blood test measuring serum 25-hydroxyvitamin D can tell you whether your levels are within a healthy range. Consider speaking with a health care provider if you have limited sun exposure, follow a diet low in vitamin D-containing foods, have a condition affecting fat absorption (such as Crohn's disease or celiac disease), are older than 70, or take any of the medications listed above. Do not adjust your dose based on a general reference guide alone. Population targets are a useful starting point, but personal dosing should always be guided by a qualified clinician.

Sources

• NIH Office of Dietary Supplements - Vitamin D (Health Professional Fact Sheet): https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
• NIH Office of Dietary Supplements - Vitamin D (Consumer Fact Sheet): https://ods.od.nih.gov/factsheets/VitaminD-Consumer/
• National Academies of Sciences, Engineering, and Medicine - Dietary Reference Intakes for Calcium and Vitamin D: https://www.ncbi.nlm.nih.gov/books/NBK56070/