Vitamin D is a fat-soluble vitamin your liver and kidneys turn into an active form, calcitriol, which helps your gut absorb calcium for bones, muscles and nerves1.
Helps your body absorb calcium, one of the main building blocks of strong bones2.
Keeps calcium and phosphate available for normal bone mineralisation, growth and remodelling1.
Your muscles need vitamin D to move2.
Your nerves need it to carry messages between your brain and your body2.
Your immune system needs vitamin D to fight off invading bacteria and viruses2.
Vitamin D from sun, food or supplements is inactive until the liver makes 25(OH)D (calcidiol) and the kidney makes calcitriol1. When blood calcium falls, parathyroid hormone boosts kidney activation, and calcitriol raises calcium absorption in the gut4.
| Food and serving | Amount |
|---|---|
| Mushrooms, white, UV-exposed, ½ cup | 366 IU |
| Soy, almond or oat milk, fortified, 1 cup | 100–144 IU |
| Milk, 2%, vitamin D fortified, 1 cup | 120 IU |
| Ready-to-eat cereal, fortified, 1 serving | 80 IU |
| Yogurt, fortified (varies by brand) | — |
| Food and serving | Amount |
|---|---|
| Trout (rainbow), farmed, cooked, 3 oz | 645 IU |
| Salmon (sockeye), cooked, 3 oz | 570 IU |
| Sardines, canned in oil, 2 sardines | 46 IU |
| Egg, 1 large (vitamin D is in the yolk) | 44 IU |
| Tuna, light, canned in water, 3 oz | 40 IU |
Very few foods naturally contain vitamin D and fortification varies by product, so check the Nutrition Facts label2. Amounts per serving from1.
No single minutes-of-sun rule: output varies with season, skin tone, age and sunscreen, and UVB doesn't pass through window glass1.
Most U.S. milk and many soy, almond and oat milks are fortified, as are many cereals and some yogurts2.
Both raise blood levels; D₃ tends to raise them more and for longer. Animal-free D₃ from lichen exists1.
The same reference table draws the reference lines on your charts in Ayuvo. Needs differ in pregnancy and breastfeeding, which are not covered here.
| Age | Women | Men | Upper limit |
|---|---|---|---|
| 19–30 | 15 mcg (600 IU) | 15 mcg (600 IU) | 100 mcg (4,000 IU) |
| 31–50 | 15 mcg (600 IU) | 15 mcg (600 IU) | 100 mcg (4,000 IU) |
| 51–70 | 15 mcg (600 IU) | 15 mcg (600 IU) | 100 mcg (4,000 IU) |
| 71+ | 20 mcg (800 IU) | 20 mcg (800 IU) | 100 mcg (4,000 IU) |
RDA (Recommended Dietary Allowance) is the daily amount that meets the needs of nearly all healthy people. Per day, for adults1.
Upper limit (UL) is the most per day that is unlikely to cause harm. Applies to food, drinks and supplements combined.
Signs like these have many possible causes. They are a reason to talk to a clinician, not to self-treat.
Low vitamin D causes rickets in children and osteomalacia in teens and adults, with bone pain and muscle weakness2.
Too much, almost always from supplements, can push blood levels very high, and extreme levels can cause kidney failure and irregular heartbeat2.
25(OH)D is the main blood marker of vitamin D status; the active form, 1,25(OH)₂D, is not a good status marker1. An Indian expert consensus uses somewhat different categories, so read results with your lab's ranges and a clinician3.
| 25(OH)D | What it may mean |
|---|---|
| < 12 ng/mL (< 30 nmol/L) | Deficiency risk |
| 12–20 ng/mL (30–50 nmol/L) | Potential inadequacy |
| ≥ 20 ng/mL (≥ 50 nmol/L) | Adequate for most people |
| > 50 ng/mL (> 125 nmol/L) | Potentially associated with adverse effects |
Labs use different units and ranges. Your clinician reads a result alongside your history and other tests.
Supplements contain vitamin D₂ or D₃, and because vitamin D is fat-soluble it is absorbed well with a meal or snack that contains some fat2.
Raises blood 25(OH)D more and keeps it higher for longer than D₂ in most studies1.
Made by UV-irradiating ergosterol from yeast; also raises blood 25(OH)D1.
Most D₃ is made from sheep's-wool lanolin; animal-free D₃ from lichen is also available1.
Supplements can interact with medicines. Talk to a clinician or pharmacist before you start one, especially at high doses.
Your skin makes vitamin D from UVB light, but how much depends on season, time of day, skin tone, age, clouds, smog and sunscreen, and sunlight through window glass doesn't count. That's why there is no single reliable minutes-of-sun rule, and UV exposure also raises skin cancer risk.
Both forms raise blood 25(OH)D, but most evidence shows D₃ raises it more and keeps it higher for longer. If you avoid animal products, look for D₃ sourced from lichen or check the source with the manufacturer.
No. High-dose weekly regimens are treatment protocols that a clinician sets for a limited period, usually after a blood test shows low 25(OH)D, and then monitors. They are not meant as an everyday supplement, and routine intake should stay within the upper limit on this page.
Ayuvo charts vitamin D by day, week, month and year, with the reference lines from this page, personalised by age and sex where they differ. Supplements you log in Medications count too. Free, with no account.
Or read the code: Ayuvo is open source
Facts on this page come from these sources, checked on the dates shown. Intake numbers come from Ayuvo's shared reference table, which cites the sources marked for them.
General information, not medical advice. This guide is for healthy adults and does not cover pregnancy, breastfeeding, children or medical conditions. It cannot diagnose or treat anything. Talk to a clinician before starting high-dose supplements, or if you think you may have too little or too much of a nutrient. Spotted an error? Email us.