Tool
Dose totals and upper limits
Add up the vitamins and minerals in everything you take, and see each total next to its adult upper limit: the most a healthy adult can take each day without likely harm, as set by the US National Academies. Vitamin D, zinc, vitamin B6 and magnesium can add up when several products contain them. Your list stays in this browser.
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Add the amounts from your labels to see your totals.
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Questions to take along
- “Does anything on this list interact with my medicines or a health condition I have?”
This isn’t a full interaction check, and it doesn’t know your medicines or your diet. Print this page and take it with you.
Adult upper limits, per day
The tolerable upper intake level (UL) is the highest daily intake unlikely to harm a healthy adult. It is not a goal and not a dose to aim for. Most limits count food and supplements together; a few count supplements only, and the table says which.
| Nutrient | Adult limit | What counts | Based on | Source |
|---|---|---|---|---|
| Vitamin A (preformed) | 3,000 mcg RAE (10,000 IU) | Preformed vitamin A only: retinol and its esters, such as retinyl palmitate. Beta-carotene does not count | Based on a higher risk of liver problems and of birth defects. | NIH ODS (updated March 10, 2025) |
| Vitamin D | 100 mcg (4,000 IU) | Total daily intake | Too much vitamin D raises blood calcium; toxicity almost always comes from supplements, and taking calcium supplements with it may add to the risk. | NIH ODS (updated June 27, 2025) |
| Vitamin E | 1,000 mg (1,500 IU natural or 1,100 IU synthetic) | Supplements: every form of supplemental alpha-tocopherol | Based on the risk of bleeding; trials have linked high-dose vitamin E supplements to a higher risk of bleeding strokes. | NIH ODS (updated October 19, 2026) |
| Vitamin C | 2,000 mg | Food and supplements | High doses can cause diarrhea, nausea and stomach cramps. | NIH ODS (updated July 31, 2025) |
| Vitamin B6 | 100 mg | Food and supplements | Taken in large amounts for months, B6 can damage the nerves that carry feeling (sensory neuropathy). In 2023 the European Food Safety Authority set a lower adult limit of 12 mg a day, based on reviews of nerve damage. | NIH ODS (updated June 16, 2023) |
| Niacin | 35 mg | Supplements only: both nicotinic acid and nicotinamide (niacinamide). Niacin in food does not count | Based on skin flushing, which nicotinic acid typically causes from 30 to 50 mg. | NIH ODS (updated November 18, 2022) |
| Folic acid | 1,000 mcg | Folate from supplements and fortified foods. Folate that occurs naturally in food does not count | Large amounts can hide the anemia of a vitamin B12 deficiency while its nerve damage goes on. | NIH ODS (updated November 30, 2022) |
| Choline | 3,500 mg | Food and supplements | Based on low blood pressure and a fishy body odor. | NIH ODS (updated June 2, 2022) |
| Calcium | 2,500 mg (19 to 50); 2,000 mg (51 and over) | Total daily intake | More supplemental calcium might raise the risk of kidney stones. | NIH ODS (updated June 22, 2026) |
| Iron | 45 mg | Food and supplements | Based on stomach and gut effects of iron supplements. | NIH ODS (updated September 4, 2025) |
| Zinc | 40 mg | Food and supplements | Based on its effect on copper: 50 mg or more a day for weeks can interfere with copper absorption and lower copper levels. | NIH ODS (updated January 6, 2026) |
| Copper | 10,000 mcg (10 mg) | Food and supplements | Based on liver damage. | NIH ODS (updated October 18, 2022) |
| Selenium | 400 mcg | Food and supplements | Based on brittle or lost hair and nails, the usual signs of too much selenium. In 2023 the European Food Safety Authority set a lower adult limit of 255 mcg a day, based on reviews of hair loss. | NIH ODS (updated September 4, 2025) |
| Iodine | 1,100 mcg | Food and supplements | Too much iodine can upset the thyroid, causing goiter or an underactive or overactive thyroid. | NIH ODS (updated November 5, 2024) |
| Magnesium | 350 mg | Supplements and medicines only. Magnesium in food and drinks does not count | High doses from supplements can cause diarrhea, nausea and stomach cramps. | NIH ODS (updated January 6, 2026) |
| Manganese | 11 mg | Total daily intake | Based on blood manganese rising above the normal range and the risk to the nervous system. | NIH ODS (updated March 29, 2021) |
| Phosphorus | 4,000 mg (19 to 70); 3,000 mg (71 and over) | Food and supplements | Based on the intakes that keep blood phosphate normal. | NIH ODS (updated May 4, 2023) |
| Boron | 20 mg | Total daily intake | Set from effects on reproduction and development in animal studies. | NIH ODS (updated June 9, 2022) |
| Molybdenum | 2,000 mcg | Total daily intake | Set from effects on reproduction and development in animal studies, as there are no human studies. | NIH ODS (updated March 30, 2021) |
| Fluoride | 10 mg | All sources | Based on fluorosis of the teeth and bones. | NIH ODS (updated April 11, 2025) |
No upper limit set
For these nutrients the experts did not set an adult limit. That is not the same as “any amount is fine”, and some carry a caution of their own.
| Nutrient | Why there is no limit | Still worth knowing | Source |
|---|---|---|---|
| Vitamin K | No limit was set because vitamin K has a low potential for toxicity. | Vitamin K can have a serious interaction with warfarin and other blood thinners. | NIH ODS (updated October 22, 2026) |
| Vitamin B12 | No limit was set because of its low potential for toxicity. | – | NIH ODS (updated July 2, 2025) |
| Thiamin (B1) | No limit was set because no harm has been reported from high intakes, though the experts noted excess could still have effects. | – | NIH ODS (updated February 9, 2023) |
| Riboflavin (B2) | No limit was set because no harm has been reported, and the experts urge caution with large amounts. | – | NIH ODS (updated May 11, 2022) |
| Biotin | No limit was set because there is no evidence in people that biotin is toxic at high intakes. | High-dose biotin can make some blood test results falsely high or falsely low. Tell whoever orders your tests. | NIH ODS (updated January 10, 2022) |
| Pantothenic acid (B5) | No limit was set because no toxicity has been reported at high intakes. | – | NIH ODS (updated May 1, 2026) |
| Chromium | No limit was set because no harm has been linked to high intakes, though the data are limited. | People with kidney or liver disease might be more likely to have side effects from high chromium intakes. | NIH ODS (updated June 2, 2022) |
| Potassium | No limit was set because the reports of harm were not enough to set one. | In people whose kidneys clear potassium poorly, from kidney disease or some medicines such as ACE inhibitors or potassium-sparing diuretics, extra potassium can be dangerous. | NIH ODS (updated June 2, 2022) |
How this tool works
- You type the amount per day from each label. The tool converts units (IU to mcg for vitamin D, for example) and adds up each nutrient across your products.
- Each total is set against the adult limit for your age. The limits come from the US National Academies, as given in the NIH Office of Dietary Supplements fact sheet for each nutrient. We read every fact sheet and checked each value, unit and conversion on 7 November 2026.
- Where a fact sheet reports a lower European limit (vitamin B6 and selenium), we show it too, because the two disagree.
- The totals count only what you enter. For most nutrients food counts toward the limit as well, so your real intake is higher than the total shown.
- No grades are used here, and nothing on this page is for sale: there are no buy links.
- Your list is saved in your browser’s storage on this device. It is never sent to us, and we can’t see it.
What it doesn’t do
- It shows adult limits only. Limits for children are lower, and advice in pregnancy and breastfeeding is different.
- The limits are for healthy people. They don’t apply to someone taking a nutrient as a treatment under a doctor’s care, which the fact sheets say for several of them.
- It isn’t an interaction check. It doesn’t know your medicines, and a total under the limit can still be wrong for you.
- It never tells you what to take. Take the totals and the questions to your pharmacist or doctor.
Sources
NIH Office of Dietary Supplements, health professional fact sheets, each read on 7 November 2026. They give the Food and Nutrition Board’s Dietary Reference Intakes from the US National Academies of Sciences, Engineering, and Medicine.
- NIH ODS, Vitamin A fact sheet (updated March 10, 2025)
- NIH ODS, Vitamin D fact sheet (updated June 27, 2025)
- NIH ODS, Vitamin E fact sheet (updated October 19, 2026)
- NIH ODS, Vitamin C fact sheet (updated July 31, 2025)
- NIH ODS, Vitamin B6 fact sheet (updated June 16, 2023)
- NIH ODS, Niacin fact sheet (updated November 18, 2022)
- NIH ODS, Folate fact sheet (updated November 30, 2022)
- NIH ODS, Choline fact sheet (updated June 2, 2022)
- NIH ODS, Calcium fact sheet (updated June 22, 2026)
- NIH ODS, Iron fact sheet (updated September 4, 2025)
- NIH ODS, Zinc fact sheet (updated January 6, 2026)
- NIH ODS, Copper fact sheet (updated October 18, 2022)
- NIH ODS, Selenium fact sheet (updated September 4, 2025)
- NIH ODS, Iodine fact sheet (updated November 5, 2024)
- NIH ODS, Magnesium fact sheet (updated January 6, 2026)
- NIH ODS, Manganese fact sheet (updated March 29, 2021)
- NIH ODS, Phosphorus fact sheet (updated May 4, 2023)
- NIH ODS, Boron fact sheet (updated June 9, 2022)
- NIH ODS, Molybdenum fact sheet (updated March 30, 2021)
- NIH ODS, Fluoride fact sheet (updated April 11, 2025)
- NIH ODS, Vitamin K fact sheet (updated October 22, 2026)
- NIH ODS, Vitamin B12 fact sheet (updated July 2, 2025)
- NIH ODS, Thiamin fact sheet (updated February 9, 2023)
- NIH ODS, Riboflavin fact sheet (updated May 11, 2022)
- NIH ODS, Biotin fact sheet (updated January 10, 2022)
- NIH ODS, Pantothenic Acid fact sheet (updated May 1, 2026)
- NIH ODS, Chromium fact sheet (updated June 2, 2022)
- NIH ODS, Potassium fact sheet (updated June 2, 2022)
See also the myth checker, and how we grade evidence.