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FITNESS WORLDWHAT THE EVIDENCE ACTUALLY SAYS.
CHECK THE EVIDENCESupplement Evidence Index
FITNESS WORLD EVIDENCE SYSTEM

Supplement Evidence Index

Popular supplements often carry dozens of claims. Fitness World separates what is supported, what is uncertain and what matters before you spend.

Unbranded white supplement bottle beside loose red and white capsules.
HOW TO USE THIS INDEX

Judge the claim, not the supplement.

A supplement can have strong evidence for one outcome and weak evidence for another. Fitness World separates the claim, the evidence and the practical decision instead of assigning one universal score.

1Claim

What outcome is being promised?

2Evidence

How consistently is that outcome supported?

3Context

Who was studied, at what dose and for what purpose?

4Decision

Does using or buying it solve a real problem?

CREATINE

One supplement. Different claims.

Creatine is a useful example of why claim-level evidence matters.

STRONG

Strength & muscle with training

One of the better-supported uses. Training remains the foundation.

READ THE EVIDENCE →
CONTEXT MATTERS

Healthy aging

Potentially useful in midlife and older age, especially alongside resistance training.

CREATINE AFTER 40 →
STRONG

Choosing a form

Monohydrate has the strongest evidence base and is usually the better-value default.

COMPARE FORMS →
MAGNESIUM

Useful nutrient. Overextended marketing.

LIMITED / MIXED Magnesium for sleepMagnesium Glycinate vs CitrateSTRONG Magnesium-rich foods as the default sourceCreatine and Hair Loss: What the Research Can — and Cannot — Tell UsAshwagandha for Stress: Evidence and SafetyMelatonin for Adults: When Does It Help Sleep?Curcumin for Knee Osteoarthritis: What Pain Studies SuggestIs Magnesium Glycinate Worth It for Sleep?
OTHER COMMON DECISIONS

Check the specific outcome before you buy.

OUTCOME-SPECIFIC Omega-3s: which claims hold up?MIXED Collagen supplements: what do they actually do?CONTEXT-SPECIFIC Do you need electrolyte powder?LIMITED Greens powdersExpensive multivitamins: worth it?Do you actually need a fiber supplement?Menopause supplement claimsINSUFFICIENT “GLP-1 supplement” marketing claimsDo Greens Powders Replace Vegetables?Does Berberine Work Like Ozempic?
DECISION GUIDE

Start with what you are trying to solve.

“I’m considering creatine after 40.”“I want magnesium for sleep.”“I’m thinking about collagen powder.”“Are electrolytes worth buying every day?”“Can greens powder replace better food?”“Is a premium multivitamin worth more?”
FITNESS WORLD EVIDENCE SYSTEM

Go from evidence to a clearer decision.

For oral-health claims, compare the oral probiotics evidence guide with our ProDentim review. For prostate-product claims, see the ProstaVive review.

ALL CLAIMS

Evidence Index

Search health claims across Fitness World.

EXPLORE →
COMPARE

Compare meaningful differences

Separate useful differences from marketing.

COMPARE →
VALUE

Evidence Reviews

See whether a purchase earns its place in a real routine.

CHECK VALUE →
NEW INVESTIGATIONS

Latest evidence checks

New Fitness World investigations connected to this evidence hub.

Creatine for Healthy Aging: Is the Hype Ahead of the Evidence?Magnesium Supplements: Which Claims Actually Have Evidence?Multivitamins: Who May Actually Benefit?Vitamin D Supplements: Who Actually Needs Them?Collagen for Joints vs Skin vs Muscle: Which Claims Hold Up?