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How we rate

We don't give opinions. We report what the evidence says.

Each check finds the strongest research on a claim, places it on the evidence ladder, and rates it by a fixed rule. Signal is published by New Age Longevity, an independent publisher. AI helps us find and summarise research; a human editor checks every claim against its source before anything is published.

The evidence ladder

Not all studies are equal. Stronger evidence sits higher.

  1. 1Guidelines and expert position statementsExpert bodies weighing all the evidence, such as health authorities and scientific societies.
  2. 2Reviews of randomised trialsSystematic reviews that pool many controlled trials in people.
  3. 3Large long-term studies of peopleCohort studies following thousands of people for years, and reviews of them.
  4. 4Small or short human trialsTrials with tens of people, or that run for weeks rather than years.
  5. 5Animal and lab studiesCells, worms, mice. Useful for ideas, not for decisions.

The rating rule

Where the strongest evidence sits decides the rating.

The evidence saysWorks

Do it, if it fits your goals.

The strongest evidence in people (ladder levels 1 to 3) is large, consistent and points the same way.

The evidence saysPromising

Worth watching. Not worth paying a premium for yet.

There is level 2 or 3 evidence, but it is small, short-term or mixed. Could move up or down as evidence lands.

The evidence saysUnproven

Save your money.

Only small or short human trials (level 4), animal and lab studies (level 5), or trials that failed.

The rules

  1. 01The evidence decides, not us.Every rating follows from where the strongest human evidence sits on the ladder, so anyone reading the same sources should reach the same answer.
  2. 02Every check shows its sources.We name the studies behind each rating, say what kind of evidence they are and how many people they covered, and link them.
  3. 03People, not mice.Animal and lab studies never earn more than Unproven. They tell us what to watch, not what to buy.
  4. 04No sponsor touches a rating.If we ever run paid placements, they are labelled, kept separate and never sit inside an evidence check.
  5. 05Ratings change when evidence does.When new research lands, we update the page and say what changed. We don't bury it.
  6. 06We only report what was measured.No testimonials and no claims beyond what studies found. Signal is general information, not medical advice.