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Evidence-graded supplement library

Clear supplement answers, without the marketing claims.

Each guide separates established uses from promising research, weak evidence and unanswered questions. Dosage, safety, interactions and different forms are explained in plain English.

Guidelines firstHuman trials prioritizedEvery benefit gradedNo product sponsorship

Published guides

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65 results

In-depth guideSupplementsChamomile: Sleep Evidence and SafetyCompare chamomile tea and extracts, newer sleep research and anxiety trials. Understand uncertain benefits, allergies, medicine interactions and pregnancy gaps.Updated Sep 21, 20265 minute read

In-depth guideSupplementsL-Theanine: Sleep, Focus, Dose Evidence & SafetySee what L-theanine trials show for sleep, attention and stress, why caffeine changes the evidence, studied doses, safety limits and product checks.Updated Aug 29, 202616 minute read

In-depth guideSupplementsMelatonin: Dose, Timing, Sleep, Jet Lag & Safety | LongevityMateEvidence-based melatonin guide covering dose and timing, insomnia, jet lag, delayed sleep phase, children, long-term safety, interactions and product quality.Updated Aug 10, 202639 minute read

In-depth guideSupplementsMilk Thistle (Silymarin): Evidence and SafetyUnderstand milk thistle’s liver claims, uncertain clinical benefits and product-quality concerns. See what newer reviews and placebo-controlled trials found.Updated Sep 20, 20265 minute read

In-depth guideSupplementsSelenium Supplements: Benefits, Dose, Food Sources and SafetyA careful selenium guide covering essential functions, food variability, studied doses, cancer and thyroid evidence, US and European upper limits, interactions and toxicity signs.Updated Sep 4, 202616 minute read

In-depth guideSupplementsSt John's Wort: Evidence, Product Differences and InteractionsReview St John’s wort depression evidence, extract differences, serious medicine interactions and safety limits without selecting a treatment or dose.Updated Sep 29, 20265 minute read

In-depth guideSupplementsValerian SupplementsReview valerian sleep evidence, including the difference between perceived and measured improvement, varied preparations and uncertain long-term safety.Updated Sep 10, 20265 minute read

In-depth guideSupplementsNiacin SupplementsCompare niacin forms, understand why better cholesterol numbers did not establish added cardiovascular benefit in statin trials, and review high-dose safety.Updated Sep 9, 20265 minute read

In-depth guideSupplementsZinc supplements: benefits, dosage, forms and copper safetyA practical zinc guide covering deficiency, colds, elemental dose, forms, copper depletion, interactions, blood tests and who should avoid high doses.Updated Aug 8, 202624 minute read

In-depth guideSupplementsCocoa Flavanols: What the Heart Trials Actually FoundA clear look at cocoa flavanol trial findings, modest blood-pressure changes, product differences and why the evidence does not prove cardiovascular prevention.Updated Sep 24, 20268 minute read

In-depth guideSupplementsCollagen Peptides: Skin, Joint and Protein EvidenceA balanced guide to collagen peptides, including conflicting skin evidence, knee osteoarthritis findings, muscle protein limits, product forms, quality checks and safety.Updated Sep 6, 202617 minute read

In-depth guideSupplementsTart Cherry Supplements: Recovery Evidence and LimitsA practical guide to Montmorency tart cherry juice, concentrate and powder, with exercise-recovery trial results, uncertainty, label checks and safety limits.Updated Sep 26, 20268 minute read

In-depth guideSupplementsOat and Barley Beta-Glucan: Evidence and LabelsLearn what oat and barley beta-glucan is, how the cholesterol evidence applies to specific products, and why a regulatory claim is not a personal dose.Updated Sep 25, 20268 minute read

In-depth guideSupplements5-HTP: Mood, Sleep Evidence & SafetySee what 5-HTP research actually shows for mood and sleep, why no universal dose is established, and which medicine interactions need caution.Updated Sep 2, 202614 minute read

In-depth guideSupplementsElderberry: Cold and Flu EvidenceReview uncertain elderberry benefits, a negative influenza trial, product differences and raw-plant risks. Learn what current evidence can and cannot support.Updated Sep 21, 20265 minute read

In-depth guideSupplementsRhodiola Rosea: Evidence, Dose & SafetyUnderstand Rhodiola rosea evidence for fatigue, stress, mood and exercise, plus product identity, insomnia risk and medicine interactions.Updated Aug 30, 202617 minute read

In-depth guideSupplementsD-Mannose SupplementsUnderstand D-mannose urinary-health claims, the large placebo-controlled trial, recent reviews and safety gaps. A proposed mechanism is not proven prevention.Updated Sep 12, 20265 minute read

In-depth guideSupplementsEchinacea: Evidence and SafetyExplore echinacea’s mixed cold evidence, including newer reviews. Compare prevention with treatment and understand product differences, allergies and interactions.Updated Sep 20, 20265 minute read

In-depth guideSupplementsGinkgo Biloba: Memory Evidence and SafetySeparate ginkgo dementia-prevention claims from symptom studies. Review the 2026 evidence, extract differences, bleeding interactions and safety uncertainty.Updated Sep 13, 20265 minute read

In-depth guideSupplementsVitamin A: Benefits, Dose, Retinol, Beta-Carotene & Safety | LongevityMateEvidence-based vitamin A guide covering retinol vs beta-carotene, dose and IU conversion, pregnancy, smokers, toxicity, deficiency, food, forms and testing.Updated Aug 10, 202638 minute read

In-depth guideSupplementsVitamin E Supplements: Evidence, Label Units and SafetyUnderstand vitamin E supplement evidence, natural and synthetic label units, prevention-trial findings, bleeding risks and when clinical advice matters.Updated Sep 8, 20265 minute read

In-depth guideSupplementsAlpha-Lipoic Acid: Neuropathy Evidence, Forms, Dose & SafetyEvidence-graded alpha-lipoic acid guide covering oral versus IV neuropathy evidence, studied doses, metabolic claims, R-ALA limits, interactions, side effects and high-risk groups.Updated Sep 3, 202616 minute read

In-depth guideSupplementsGarlic Supplements: Benefits and SafetyCompare garlic extracts, powder and food, including modest average benefits, a negative cholesterol trial, bleeding precautions and limits of the evidence.Updated Sep 22, 20265 minute read

In-depth guideSupplementsPsyllium: Benefits, Dose, Cholesterol & Safety | LongevityMateEvidence-based psyllium guide covering constipation, LDL and ApoB, blood sugar, dose, water, timing, interactions, forms, pregnancy and side effects.Updated Aug 10, 202632 minute read

Coming next

The next evidence guides in our research queue

These are previews, not finished guide links. Each card has a stable page anchor until its full research review is published.

Omega-3 (EPA and DHA)

Heart outcomes, triglycerides, forms and product quality

Research in progress Coming next

Ashwagandha

Stress, sleep, thyroid cautions and evidence limits

Research in progress Coming next

Calcium

Bone health, dietary intake, dosage, and heart safety

Research in progress Coming next

Riboflavin (vitamin B2)

Migraine prevention, studied doses and safety

Research in progress

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See how LongevityMate grades evidence

Strong, moderate, limited and insufficient are not marketing labels. They reflect study quality, consistency, directness and how confidently the research applies to people.

Read our methodology