Supplements: does it work?
In the U.S., dietary supplements do not need FDA approval before they are sold, under the Dietary Supplement Health and Education Act of 1994 (source: FDA, checked Nov. 3, 2026).
By Mongevity Desk · About us · Corrections
Vitamin D, omega-3, NAD+, collagen, magnesium, melatonin: the label promises a lot, and the FDA does not check those promises before a supplement goes on sale. This guide shows what studies in people found for each one we cover, with our A–E evidence grade.
We name supplements by ingredient, never by brand, and we do not sell or link to any product. For doses and safety limits, the official reference is the NIH Office of Dietary Supplements (linked below).
Tell your doctor or pharmacist about any supplement you take: some interact with prescription medicines.
Not covered yet: NAD+, collagen and melatonin. Each will appear here when we publish a study on it in people.
Every study we've graded
- AStrong: large randomized trials or meta-analyses in people, with hard outcomes.
- BGood: randomized trials in people with smaller samples, shorter follow-up or lab markers.
- CModerate: well-done observational studies in people.
- DLimited: small or early studies in people.
- EVery limited: studies in cells or animals only.
| Study | Topic | Evidence | Why this grade | Original paper | Date |
|---|---|---|---|---|---|
| Supplements: what the evidence says | |||||
| Severe vitamin D deficiency was linked to higher death risk; supplements to lower risk | Lifestyle | C | Very large two-country cohort with consistent methods, but observational, with supplement use estimated from purchases. | Paper | Nov. 3, 2026 |
| Magnesium pills showed small, uncertain effects on blood vessels and blood pressure | Lifestyle | C | Meta-analysis of placebo-controlled trials; few, small trials, inconsistent effects and a high-dose finding from 2 studies. | Paper | Nov. 3, 2026 |
| High-dose fish oil with a heart-healthy diet lowered a ceramide-based risk score | Lifestyle | C | Randomized trial with an exploratory biomarker outcome; unblinded, high dose and no clinical events measured. | Paper | Nov. 3, 2026 |
Questions people ask
Which supplements actually work for healthy aging?
In the U.S., dietary supplements do not need FDA approval before they are sold, under the Dietary Supplement Health and Education Act of 1994 (source: FDA, checked Nov. 3, 2026).
Where the data comes from
- NIH Office of Dietary Supplements: fact sheets: Official fact sheets for each supplement: doses, evidence and risks.
- PubMed, U.S. National Library of Medicine: Every study we grade links to the original journal article.
- ClinicalTrials.gov, National Institutes of Health: The official registry of clinical trials: phase, status, dates and results, filed by the researchers.
- FDA: dietary supplements: FDA warnings, recalls and products with hidden ingredients.
Mongevity explains research. It does not give medical advice.