1. Define the question
Write the reason for comparing the products. “Which is better?” is too broad. A useful question is “Which format is easier to use without duplicating my current multivitamin?”
If the goals are different, the products may not be true alternatives.
2. Normalise the serving
Compare one day with one day, not one scoop with one capsule. Record the manufacturer’s daily serving, number of days per package and cost per day.
Then compare each active amount, unit, NRV and warning.
3. Check evidence and seller
Separate evidence for an ingredient from evidence for the complete product. Check whether the claim on the page is narrower or broader than the evidence.
Verify the official seller, return conditions, current label and commercial relationship of the person recommending the product.