No regulator approves a dietary supplement because an algorithm picked it. In Canada, natural health products need a Health Canada product license, shown as an eight-digit NPN on the label, while in the United States the FDA does not approve supplements before they are marketed. A 2025 study of an AI search tool answering questions about 30 supplements found that only 33.1 percent of its responses matched a physician-built reference, so AI output is best treated as a starting point for questions to a pharmacist or doctor, not as a recommendation.
Key takeaways
- Health Canada requires a product license and an NPN before a natural health product is sold; the FDA has no authority to approve supplements before marketing.
- In a JMIR AI study published October 29, 2025, Microsoft Copilot answered 33.1 percent of 540 supplement questions in line with the reference assessment.
- 72.7 percent of the 3,081 sources that tool cited came from unverified websites, mostly blogs and similar pages.
- Some supplements, such as St. John's wort, can interact with prescription medicines, which a chatbot cannot check without a full medication history.
- This article is general information and not medical advice.
Two systems, neither with pre-market approval for effect
The rules differ by country, and an AI tool that ignores the difference can mislead. Health Canada states that all natural health products sold in Canada require a product license before marketing. The application covers medicinal ingredients, source, potency, non-medicinal ingredients, and recommended use, and a licensed product carries NPN followed by eight digits (homeopathic medicines use DIN-HM). Health Canada describes the number as a sign that the product was reviewed for safety, effectiveness, and quality when used as the label directs.
The United States works differently. Under the Dietary Supplement Health and Education Act of 1994, the FDA says in its questions and answers on dietary supplements that it has no authority to approve them before they are marketed, and manufacturers and distributors carry the initial responsibility for safety. The agency acts after a product is on the market and takes reports of harm through its Safety Reporting Portal. Its consumer page also notes that some supplements might interact with medicines or other supplements. A recommendation engine can therefore point to a product that is legal to sell without any regulator having judged that it works.
What a 2025 study measured
Researchers at Japanese universities tested Microsoft Copilot (formerly Bing Chat) with 180 questions, each pairing one of 30 supplements with one of six conditions, in three response modes, which produced 540 answers. All questions were in Japanese, and data were collected from July to September 2023. Two licensed physicians built a reference judgment from reports of Japan's National Institute of Health and Nutrition and rated each answer as effective, uncertain, or ineffective.
The overall match rate with that reference was 33.1 percent (179 of 540 answers). Accuracy ranged from 49 percent for cancer questions to 19 percent for constipation. The tool cited 3,081 sources, and 72.7 percent of them were unverified, mainly unregulated medical knowledge sites such as blogs. In roughly one response in ten, the cited source did not support the statement attached to it, and 48.5 percent of answers suggested consulting a health care professional. The authors link the low accuracy partly to an unsettled evidence base and to the quantity of unverified supplement content online.
The limits matter. The paper tested one tool, in one language, at a time when its three modes still existed, so current products may behave differently. The paper also contains small internal inconsistencies in some reported figures, such as a P value stated two ways, which is a reason to treat the numbers as indicative rather than exact.
Why personal context is the hard part
Supplements are widely used. The National Center for Health Statistics reported that 57.6 percent of US adults aged 20 and over took at least one supplement in the previous 30 days in 2017-2018, with multivitamin-mineral products the most common, followed by vitamin D and omega-3 products. Many of those users also take prescription medicines, which is where generic advice breaks down.
The US National Center for Complementary and Integrative Health states that St. John's wort can interact, sometimes dangerously, with many medicines, and lists antidepressants, birth control pills, and the blood thinner warfarin among those whose effects may be weakened. Whether such an interaction matters for one person depends on doses, other drugs, and health conditions that a chat window rarely captures. Pharmacists and physicians have access to that history; a general-purpose chatbot usually does not.
How to check an AI answer about a supplement
The table lists claims that commonly appear in AI answers and where each can be verified. It is an orientation aid, not clinical guidance.
| Claim in an AI answer | Where to check it | What the check can show |
|---|---|---|
| This product is approved in Canada | The NPN on the label, searched in Health Canada's licensed natural health products database | Whether a license exists and what uses were authorized |
| This product is FDA approved | FDA consumer pages on dietary supplements | The FDA does not approve supplements before sale, so the statement is a red flag |
| A study shows this works | The cited paper itself | Whether the link exists, and whether the study supports the stated effect |
| This is safe with your medicines | A pharmacist, doctor, or other health care professional | Interactions based on the actual medication list |
| A harmful reaction was caused by this product | Health Canada reporting or the FDA Safety Reporting Portal | How to report; the first step is contacting a health care provider |
Questions worth asking before using any supplement tool
- Does the tool say which sources it used, and do those sources open and match the claim?
- Does it ask about current medicines, pregnancy, and diagnosed conditions, or does it skip them?
- Does it distinguish a licensed product from an unlicensed one, or a nutrient from a branded blend?
- Who operates the tool, and does the operator sell the products it suggests?
- What happens to the health details typed into it?
This article gives general information about regulation and research on AI tools. It is not medical advice, it does not recommend any product or dose, and it cannot assess a particular person's needs. Questions about supplements, medicines, or symptoms belong with a licensed health care professional, and the regulators listed below publish the official rules.
FAQ
Can an AI tool tell which supplements a person needs?
Not reliably. The 2025 Copilot study found that about a third of answers matched a physician-built reference, and a tool without access to a person's medicines and health history cannot assess interactions.
Does the FDA approve dietary supplements?
No. By its own statement, the FDA lacks authority to approve dietary supplements before they are marketed. Manufacturers and distributors hold initial responsibility for safety, and the agency can act against unsafe or misbranded products afterward.
What does an NPN on a Canadian label mean?
It shows that Health Canada issued a product license for a natural health product. The license rests on information the applicant supplied, including ingredients, potency, and recommended use.
Are AI answers about supplements always wrong?
No. In the Copilot study, accuracy varied by condition, and nearly half of answers advised seeing a health care professional. The finding is that quality was uneven and that the sources were often weak, not that every answer failed.
Related reading
- How AI in healthcare is regulated in Canada
- How AI chatbots hold conversations
- Home AI products for everyday use
- AI-driven personalization in social media
More in AI in health.
Last verified: October 2026
Sources
- Product Licensing, Natural and Non-prescription Health Products Directorate, Health Canada
- Information Kit: Regulation of Natural Health Products, Health Canada
- Questions and Answers on Dietary Supplements, U.S. Food and Drug Administration, content current as of August 27, 2026
- Dietary Supplement Use Among Adults: United States, 2017-2018, NCHS Data Brief No. 399, National Center for Health Statistics, February 2021
- St. John's Wort, National Center for Complementary and Integrative Health, May 2025
- Liu M et al., Evaluating the Reliability and Accuracy of an AI-Powered Search Engine in Providing Responses on Dietary Supplements, JMIR AI, October 29, 2025