Health Britannica · Supplement Safety · NIH label records read 10 January 2026
Searches and sums run in your browser from static files. Nothing about your stack is sent anywhere.
Built by Vincent Wesley Couey (ORCID 0009-0005-6869-308X) from the NIH Dietary Supplement Label Database and the NIH Office of Dietary Supplements fact sheets. Not yet reviewed by a clinician; the checker reports published records and makes no clinical claim. The earlier Supplement Stack Auditor takes amounts you type yourself.
You check a stack by adding the same nutrient across every product, not by judging each bottle alone.
36% of niacin labels reach the adult limit in one day's stated servings, the highest of the 19 nutrients measured, and 6% to 3% of the labels for the next several nutrients do too. The measure is a label's first listed serving at its stated minimum daily servings, from supplements alone, against the adult 19 to 50 limit.
Counts of labels with an assessable amount, 91,581 of 214,780 labels carry at least one nutrient with an NIH limit. The method was written down and hashed before any label was compared, and a separate program recomputed a random 500 labels with no mismatch. A label that enters a compound's weight under the nutrient's name would overstate the amount.
You read a nutrient's bar as shares of one limit: the full bar is the limit, and each colour is one product's part of it.
Illustration with made-up labels, not real products.
Three labels together: 260% of the limit.
Product A, 5,000 IUProduct B, 3,400 IUProduct C, 800 IU
The most common mistake treats the limit as the dose that is safe up to and harmful beyond. The limit is set from evidence on harm at the group level.
"I am at 120 percent of the limit, so this is poisoning me," or "I am at 90 percent, so I am fine."
Read the share as where the evidence on harm starts, add what you eat, and ask a pharmacist or doctor what suits you. NIH explains each limit in its NIH vitamin D fact sheet, NIH vitamin A fact sheet, NIH vitamin E fact sheet, NIH folate fact sheet, NIH niacin fact sheet, NIH magnesium fact sheet, NIH zinc fact sheet, NIH vitamin B6 fact sheet, NIH iron fact sheet.
What counts toward a limit follows the NIH sheet's own wording for that nutrient. Preformed vitamin A counts retinol and its esters but not carotene. Vitamin E counts supplemental alpha-tocopherol. Folic acid counts the synthetic form and not food folate. Niacin counts nicotinic acid and nicotinamide. Magnesium counts supplemental magnesium only. Other limits cover total intake, so the supplement figure is a floor for what a person takes in. Units convert by the NIH sheets' own rules: 1 mcg vitamin D is 40 IU, 1 IU of natural vitamin E is 0.67 mg, 1 IU of retinol is 0.3 mcg RAE, and 1 mcg of dietary folate equivalents is 0.6 mcg of folic acid taken with food.
Search for each product by name or barcode, add it, set the servings you take a day, and choose your age group. The checker adds each nutrient across every product and compares the total with the NIH upper limit, with a bar per nutrient that shows which product supplies how much.
A tolerable upper intake level is the highest daily intake the US National Academies judged unlikely to cause harm in nearly everyone in a group. It is a ceiling set from the evidence on harm, not a target and not a threshold at which harm is certain. The NIH Office of Dietary Supplements publishes each level in its fact sheets.
No. A limit marks where the evidence on harm begins, and many people take amounts above one under medical advice. The checker reports the share of the limit and never calls a product safe or unsafe. A pharmacist or doctor can say what suits you.
Some limits depend on the form of the nutrient, such as preformed vitamin A, natural or synthetic vitamin E, and folic acid compared with food folate. When a label does not state the form, the low end of the range counts none of the uncertain amount and the high end counts all of it, and the page says so.
The amounts come from 214,780 label records in the NIH Dietary Supplement Label Database, exported on 10 January 2026. A record is what the maker declared on the date it was filed, not a laboratory test, and a product may have changed or left the market since.
No. No open structured dataset of supplement and drug interactions exists, so the checker compares amounts with limits only. For medicines, ask a pharmacist, and see the NIH fact sheets for each nutrient.
No. The searches and the sums run in your browser from static files. The link you can copy holds only the label numbers and servings, so anyone you send it to sees the same result.
The checker was built from 214,780 NIH label records, 27 NIH fact sheets and a method written before any label was compared. The tables, the limits and the protocol are published with the Supplement Label Atlas. The same code runs the checker and the Atlas counts. What the independent check found. Further reading: the National Academies Dietary Reference Intakes; the FDA nutrition labeling rule, 21 CFR 101.9; the FDA dietary supplements page; the FDA's dietary supplement labeling guide; report a problem through the Safety Reporting Portal.