Start with the regulatory reality
In the United States, dietary supplements are not approved by the FDA before they go on sale. Manufacturers are responsible for ensuring their own products are safe and accurately labelled, and regulatory action generally happens after a problem emerges.
This is not a conspiracy, it is the statutory framework. But it means the presence of a product on a shelf tells you approximately nothing about whether it works or whether the bottle contains what the label says.
Check the serving size first
Turn the bottle around and find the serving size before you look at anything else. A bottle with 90 capsules at a three-capsule serving is a 30-day supply, and the price per month is triple what the shelf price suggested.
This is also where dose comparisons live. If a study used a particular daily amount and the label delivers a third of that per serving, you need three servings for the research to be relevant.
Then find the proprietary blends
If you see 'proprietary blend' followed by a total milligram figure, you cannot determine the dose of anything inside it. Ingredients are listed in descending order by weight and no further detail is required.
Treat this as disqualifying. There is no consumer benefit to the structure — its entire function is to prevent you from checking the dose against the evidence.
Look for third-party testing marks
Independent certification programmes test whether the contents match the label and screen for contaminants. Look for marks from established testing organisations, and verify the specific product on the certifier's own website rather than trusting the logo on the bottle.
Certification confirms the product contains what it claims in the amounts stated. It says nothing about whether those ingredients do anything useful. Two separate questions.
Read the structure/function claim and the disclaimer
Phrases like 'supports metabolism' or 'promotes healthy weight management' are structure/function claims. They are permitted without pre-approval, and they are deliberately vague.
They must be accompanied by a disclaimer stating the claim has not been evaluated by the FDA and the product is not intended to diagnose, treat, cure or prevent disease. Where you find that disclaimer on the packaging tells you how the company thinks about disclosure generally.
- 'Supports healthy metabolism' — permitted, vague, unverifiable
- 'Clinically shown to reduce body fat' — a much stronger claim requiring real substantiation
- 'Treats obesity' — a disease claim, not permitted for a supplement
Check for interactions before you buy
Supplements can interact meaningfully with prescription medication. St John's wort affects the metabolism of a long list of drugs; high-dose fish oil interacts with anticoagulants; concentrated green tea extract has been linked to liver injury in rare cases.
A pharmacist will check this for you for free and is one of the most underused resources in consumer health. Take the bottle in.