Nobody reviews a supplement before it goes on sale. That makes label-reading a skill worth having rather than a chore — six checks, none of which takes more than a minute, will tell you more about a product than any amount of marketing copy.
Why This Matters More Than for Medicines
Prescription medications are reviewed by the FDA before sale, manufactured to enforced standards, and monitored afterwards. Dietary supplements are not. They require no pre-market approval, the FDA does not evaluate them for safety or effectiveness in advance, and manufacturers are responsible for their own labelling.
That shifts a lot of the verification burden onto you. The good news is that most of what you need is on the label, if you know where to look.
1. Find the Amounts
Look at the Supplement Facts panel and find the amount of each active ingredient. If every ingredient has its own number, good. If several are grouped under a single combined figure, you are looking at a proprietary blend.
Proprietary blends are legal and uninformative. A blend listed at 500 mg might be 480 mg of the cheapest ingredient and 20 mg split between the two the marketing features. You cannot tell, and that is the point of the format.
Ingredients are listed in descending order by weight, which is the one clue you get. If the ingredient in the product name appears last, that is informative.
For probiotics specifically, look for strain designations and per-strain amounts. A label naming only species, with one combined figure, cannot be checked against any published research — see our probiotics guide.
2. Check the Serving Size
Amounts on the panel are per serving, and a serving is often more than one capsule. A product listing 1,725 mg per serving at three capsules per serving is a different proposition from one listing the same amount in a single capsule.
Then check servings per container against the price. A 180-capsule bottle at 3 capsules per serving is 60 servings — two months at one serving a day, or twenty days if the research dose requires three servings daily. That changes the cost calculation substantially.
3. Compare the Dose to the Research
This is the single most useful check, and almost nobody does it. Take the amount per serving and compare it to the dose used in studies of that ingredient. Most supplement marketing alludes to research conducted at doses the product does not come close to providing.
Rough reference points from the ingredients we cover:
- Inulin and fermentable fiber — research on gut hormone response typically uses several grams to around 16 g/day.
- Glucomannan — satiety trials generally use 2–4 g/day before meals with water.
- Resistant starch — commonly 15–30 g/day in trials.
- Berberine — commonly 500 mg two or three times daily, so 1,000–1,500 mg/day.
If a capsule provides 211 mg of inulin, it is providing a small fraction of the researched amount. That does not necessarily make it useless — but it does mean you should not expect a research-scale effect.
4. Look for Third-Party Certification
NSF, USP, and similar certifications mean an independent organisation has verified that the product contains what the label says and is free of specified contaminants. Given the absence of pre-market review, this is the main external check available.
Two caveats. Certification verifies contents, not effectiveness — a certified product can be certified to contain an ingredient that does not work. And its absence is not proof of a problem; certification is voluntary and costs money. But its presence is a genuine positive, and it matters most for ingredients with real pharmacological activity such as berberine.
5. Read the Claims Language
Supplements may make structure-function claims — that an ingredient supports a normal function. They may not claim to diagnose, treat, cure or prevent disease. Compliant products carry the disclaimer that statements have not been evaluated by the FDA.
- Compliant and unremarkable: "supports gut microbiome diversity," "supports healthy blood sugar metabolism."
- Signals to slow down: comparisons to Ozempic or semaglutide, specific weight-loss promises, before-and-after imagery, claims to treat a condition.
- Genuinely reassuring: a manufacturer stating what the product is not. Pendulum states its product is "not a GLP-1 agonist drug"; CoreAge Rx states its product is "not a weight-loss medication."
6. Find the Warnings and Terms
Check for contraindications, allergen statements, and storage requirements. For live probiotic products, look specifically for exclusions covering immunocompromise and recent antibiotic use — a manufacturer that publishes those is behaving responsibly.
Then check the commercial terms: is there a refund policy, and what happens with a subscription? Several products in this category offer multi-bottle bundles with no published return path, which is a poor combination for something you have never taken.
A Worked Example
Applying the routine to a real label — CoreAge Rx GLP-1 Support, which we review in full:
- Amounts: inulin 211 mg and resistant starch 100 mg are published individually — good. The three probiotic strains share one 36 mg figure with no CFU count — not checkable.
- Serving size: one capsule, 30 per bottle. Simple, and one bottle is genuinely one month.
- Dose vs research: 211 mg inulin against several grams in the literature. This is the check that matters most here.
- Certification: none stated.
- Claims: structure-function language, FDA disclaimer present, and an explicit statement that it is not a weight-loss medication — a positive.
- Warnings and terms: specific exclusions published including immunocompromise and C. difficile — a positive. No refund policy stated — a negative, particularly on a $149 six-bottle bundle.
Six checks, a few minutes, and a clear picture: transparent on fiber amounts and honest about what it is not, weak on dose relative to research and on commercial terms. That is the kind of assessment the routine produces.
Frequently Asked Questions
What is a proprietary blend and why does it matter?
A proprietary blend lists several ingredients under one combined weight, without saying how much of each is present. It is legal, and it means you cannot tell whether any individual ingredient is dosed meaningfully. A blend can be almost entirely the cheapest ingredient with trace amounts of the ones featured in the marketing.
Why does serving size matter so much?
Because the amounts on a Supplement Facts panel are per serving, not per capsule. A product advertising an impressive number may require three or four capsules to deliver it. Check servings per container against the price to work out the real cost per day, and check how many capsules you actually have to swallow.
What does third-party tested mean?
An independent organisation — commonly NSF or USP — has verified that the product contains what its label says and is free of specified contaminants. Because the FDA does not review supplements before sale, this is the main external check available. It verifies contents, not effectiveness.
How do I compare a dose to the research?
Find the amount per serving on the label, then look up the dose used in studies of that ingredient. If a capsule provides 211 mg of inulin and the research uses several grams, that is a gap worth knowing about before you buy. This single check deflates a large share of supplement marketing.
What claims language should make me cautious?
Anything claiming to treat, cure or prevent disease is not permitted for a supplement. Specific weight-loss promises, comparisons to prescription drugs, and before-and-after imagery are all signals to slow down. Compliant products use structure-function language and carry the FDA disclaimer.
Sources
- US Food & Drug Administration — Supplement Facts panel requirements and dietary supplement labelling regulation.
- US Food & Drug Administration — structure-function claims versus disease claims for dietary supplements.
- NSF International and US Pharmacopeia — third-party supplement certification programme documentation.
- International Scientific Association for Probiotics and Prebiotics — guidance on strain designation and labelling.
- US Federal Trade Commission — guidance on substantiation of health and weight-loss claims in advertising.
Supplement Disclaimer & Review Date
These statements have not been evaluated by the Food and Drug Administration. Dietary supplements are not intended to diagnose, treat, cure, or prevent any disease. Dietary supplements are not FDA-approved medications, are not reviewed by the FDA for safety or effectiveness before they go on sale, and are not a substitute for prescription treatment.
Nothing on this page is medical advice, and nothing here should be read as a promise of weight loss or of any particular result. Supplements can interact with prescription medications and are not appropriate for everyone. Talk to a doctor or pharmacist who knows your medical history before starting any supplement — particularly if you are pregnant or breastfeeding, take prescription medication, manage a chronic condition, or are already taking a GLP-1 medication.
Product details come from the manufacturer's own published materials as of the date below. Ingredients, amounts, pricing, and policies change frequently — check the current label and product page before purchasing.
Last reviewed: August 5, 2026
Related Reading
Ingredient Evidence Reviewed
The research doses to compare labels against.
The Risk in Ozempic-Alternative Claims
The claims language that should slow you down.
Supplement Comparison Table
The routine applied across every product we reviewed.
When to Talk to a Professional
What the label cannot tell you about your situation.