Why the usual comparisons fail
Ingredient count. A formula with twenty ingredients at unstated amounts is worse than one with six at stated ones. More ingredients, in a fixed capsule, means less of each.
Price. It reflects marketing budget as much as formulation. The most expensive product in a category is frequently the one spending most on persuading you.
Star ratings. Averaged across thousands of reviews, on a product whose effects are subtle and slow, by people who mostly cannot tell whether it worked. This measures enthusiasm, not efficacy.
“Clinically proven”. An unregulated phrase. It can mean a 3,000-person six-year trial or a twelve-person open-label study the company paid for. Without a citation it means nothing.
1. Compare the labels, ingredient by ingredient
Put two supplement facts panels side by side. Ask of each ingredient: is there an amount, and is that amount anywhere near what the research used?
The ginkgo trial that found something used a standardised 240 mg extract. The lutein trial used 12 mg. If a product lists ginkgo at an unspecified amount inside a blend, you cannot do this comparison — which is the point of the blend.
2. Compare what each seller admits
This sounds soft and it is the sharpest test available. Every ingredient in this category has a limitation. Two large ginkgo trials are negative. The curcumin trial had forty participants. The lutein trial needed a year.
A page that mentions none of this has made a decision about what you are allowed to know. Compare two sellers on this and the difference is usually stark.
3. Compare the refund terms, in detail
- How long — thirty days is common, sixty is better.
- From when — purchase or delivery. With shipping time, the difference can be a week or more.
- Opened or unopened — the one that matters most, since you cannot try an unopened bottle.
- Who handles it — the retailer, and whether their process is stated before you pay.
4. Compare the timeline each product promises
Against the published research, not against each other. Nothing in this category produces noticeable change in a week. A product claiming it is either describing a stimulant or describing nothing.
A product telling you the first honest checkpoint is six weeks is being accurate, even though it is a worse sales pitch.
The thing no comparison will tell you
Whether it will work for you. In every trial behind every ingredient discussed on this site, a meaningful share of participants saw no change at all. An average across a group is not a forecast for one person, and no amount of comparison shopping changes that.
Which is why the refund window is a more practical criterion than any of the others. It is the only part of the purchase that converts an unknowable question into a reversible decision. Ours runs sixty days from delivery and accepts opened bottles, which is the version of that promise that actually means something.