Independent Health Research
Evidence on supplements, traced to original research and authoritative sources.
Pure City Research prioritizes original studies, evidence syntheses, and regulatory sources. We also report study funding and disclosed conflicts where they can be identified, so readers can see the basis and limitations of each conclusion.
The Pure City standard
Evidence
reviewed for quality, funding and conflicts
We prioritize relevant human research, evidence syntheses, and regulatory sources. Funding and disclosed conflicts are reported where identified, and limitations are stated with the conclusion.
- Original and authoritative sources prioritized
- Funding and disclosed conflicts reviewed
- Evidence graded: Strong to Insufficient
Editor’s picks
Start here: natural vs synthetic, untangled
The two questions readers ask most — answered with evidence, not marketing.
Natural vs Organic
What organic certification does — and does not — establish
A comparison of certification rules, residue and contaminant evidence, and the limits of claims that one label is inherently safer or healthier.
Natural vs Chemicals
Why natural doesn’t always mean safe
“Natural” and “synthetic” do not determine safety by themselves. Risk depends on the substance, dose, exposure, population, and quality of the supporting evidence.
Explore by health concern
We organize research around what you're actually trying to understand — not around which product someone wants to sell.
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Heart & Cardiovascular
Omega-3, CoQ10, cholesterol, blood lipids.
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Diabetes & Blood Sugar
Insulin sensitivity, glucose, metabolic health.
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Blood Pressure
Minerals, vascular function, hypertension.
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Fat Loss & Metabolism
What actually moves the needle (and what doesn't).
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Sleep
Falling asleep, staying asleep, circadian rhythm.
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Stress, Anxiety & Depression
Adaptogens, amino acids, mood support.
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Gut & Digestion
Microbiome, bloating, regularity, absorption.
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Energy & Focus
Fatigue, cognition, mitochondrial support.
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Muscle Building
Protein, creatine, hypertrophy evidence.
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Cancer
Risk reduction, lifestyle, and supplement claims vs trial data.
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Eczema & Skin
Barrier care, flare management, nutrient evidence.
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Asthma & Respiratory
Triggers, management, respiratory outcomes.
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Neurology & Brain Health
Narcolepsy, cognition, neurodegenerative risk — the neurological evidence.
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Autoimmune & Inflammatory
Rheumatoid arthritis and immune-mediated inflammation evidence.
Ingredient deep dives
Each ingredient article summarizes the strength and limitations of the available evidence. Safety, interactions, funding, and disclosed conflicts are reported where the article documents them.
Magnesium
Sleep, stress, blood pressure — which form matters.
Grade under editorial review
Omega-3
Heart, mood, inflammation — EPA/DHA dosing.
Grade under editorial review
Melatonin
Sleep onset, jet lag, dose-dependent effects.
Evidence: Strong
Vitamin D
Deficiency, mood, immune — who actually needs it.
Evidence: Moderate
St John's Wort
Mild depression — with serious interaction risks.
Grade under editorial review High interaction risk
CoQ10
Heart, energy, statin-related muscle pain.
Evidence: Moderate
L-Tyrosine
Stress resilience, focus under acute pressure.
Evidence: Moderate
L-Theanine
Calm focus, caffeine pairing, anxiety support.
Evidence: Moderate
Saffron
Mood, depression — what the 34-trial meta-analysis shows.
Evidence: Moderate
Garlic
Blood pressure — allicin, aged extract, real effect size.
Evidence: Moderate
NMN
NAD+ precursors, aging, energy — human evidence vs hype.
Evidence: Moderate
Probiotics
Strain-specific benefits — which ones actually work.
Grade under editorial review
Collagen
Skin, joints — hydrolyzed collagen and what trials show.
Grade under editorial review
Berberine
Blood sugar, lipids — metabolic effects and dosing.
Evidence: Moderate
Ashwagandha
Stress, cortisol — KSM-66 and the evidence behind it.
Evidence: Moderate
Creatine
Muscle, cognition — the most-studied supplement.
Evidence: Strong
Stevia
Stevioside vs Reb A vs Reb M — which form actually works.
Evidence: Moderate
Monk Fruit
Forms, mogroside content, safety sources, and the limits of the available human evidence.
Grade under editorial review
Aspartame
IARC 2B, NutriNet-Santé, JECFA ADI — what the evidence shows.
Grade under editorial review
Sucralose
Gut microbiome shifts and glycemic effects in human RCTs.
Grade under editorial review
Saccharin
The bladder-cancer scare that was rat-specific — resolved.
Grade under editorial review
Acesulfame-K
The unreplicated cancer cohort signal — what it means.
Grade under editorial review
Whey Protein
WPC vs WPI vs WPH vs native — MPS dose-response and the leucine trigger.
Evidence: Strong
Yeast Protein
Single-cell vegan protein — one manufacturer-funded RCT, weak evidence.
Evidence: Weak
Plant Protein
Pea/soy/rice/hemp — parity with whey when dose and leucine are matched.
Grade under editorial review
Tongkat Ali
Natural testosterone booster? What human trials actually show.
Evidence: Moderate
Psyllium Husk
Nature's Ozempic? LDL and glucose yes — weight loss, weak.
Evidence: Moderate
Bovine Colostrum
Liquid gold for immunity? Athlete URTI data, beauty claims thin.
Grade under editorial review
Glutathione
Skin brightening from within? Oral weak, IV unsafe.
Evidence: Weak
Myo-Inositol
PCOS, metabolic outcomes, ovulation and fertility claims reviewed against the available evidence.
Evidence: Moderate
Nattokinase
Dissolves microclots? Modest BP effect, bleeding risk.
Evidence: Moderate
Astaxanthin
Internal sunscreen? Skin moisture yes, lipid claims weak.
Evidence: Moderate
Lion's Mane
Brain fog cure? Small pilots, thin human data.
Evidence: Weak
Rhodiola
Adaptogen for burnout? Promising but methodologically weak.
Evidence: Weak
Shilajit
Mountain mineral pitch — weak data, heavy-metal safety caveat.
Evidence: Weak
L-Glutamine
Leaky gut repair? One strong RCT in a narrow IBS subgroup; critical-illness harm signal.
Grade under editorial review
Zinc-L-Carnosine
Gastric ulcer healing and H. pylori adjunct — Japan drug, US supplement.
Evidence: Moderate
Related health and comparison articles
Condition guides and evidence-based comparisons that sit outside the 37-ingredient library.
Natural vs Organic
'Natural' has no legal definition; organic is certified — but neither is proven healthier.
Natural vs Chemicals
Why natural doesn't always mean safe, and chemical doesn't always mean dangerous.
Narcolepsy
Excessive daytime sleepiness & cataplexy — evidence-based treatments are prescription drugs; no supplement has adequate evidence.
Evidence: Moderate
Chronic Rhinosinusitis
Saline irrigation is the strongest non-drug intervention; most supplements lack CRS evidence.
Evidence: Strong
Rheumatoid Arthritis
DMARDs are standard of care; omega-3 fish oil is the best-supported supplement adjunct.
Evidence: Moderate-to-Strong
Why trust our research?
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Original sources prioritized
We prioritize original studies and regulators for verdict-bearing claims. Evidence syntheses and selected contextual sources are distinguished from original research.
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Funding & conflicts reviewed
We report study funding and disclosed conflicts where they can be verified, and consider these limitations alongside study quality and consistency.
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No hidden commerce
If we link to a product, we say so. Editorial decisions are independent of any affiliate relationship.