Supplement Guide: What the Science Actually Says

22 popular oral supplements, with evidence-based benefits separated from claims the research doesn't support — so you know what you're actually buying.

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Evidence strength: High Strong, consistent evidence Medium Moderate evidence, some caveats Low Weak but real evidence Unsupported Marketed, not currently supported

Ashwagandha

Withania somnifera — adaptogenic herb (KSM-66, Sensoril, Shoden)
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Evidence-Based Benefits

  • MediumLowers cortisol (stress hormone)
  • MediumEases perceived stress and anxiety symptoms
  • LowImproves sleep onset and quality

Insufficient-Evidence Claims

  • UnsupportedTestosterone / male fertility support
  • UnsupportedCognitive enhancement
  • UnsupportedGeneral “wellness” / rejuvenation claims
Key safety note: Possible drug-induced liver injury (NIH LiverTox class B); avoid with liver disease, thyroid conditions, or pregnancy; several countries have restricted or warned against it.

Bacopa

Bacopa monnieri — brahmi, water hyssop (CDRI 08 / KeenMind, BacoMind)
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Evidence-Based Benefits

  • MediumDelayed verbal memory recall (8–12 weeks of use)
  • LowAttention and processing speed
  • LowMood and anxiety scores

Insufficient-Evidence Claims

  • UnsupportedOverall / global cognitive enhancement
  • UnsupportedMild cognitive impairment or dementia treatment (trials ongoing)
Key safety note: GI upset is common (11% discontinue in one trial). Interacts with cholinesterase-inhibitor and anticholinergic medications; may raise thyroxine — caution in thyroid disease.

Bee Propolis

Resinous hive material — European poplar-type, Brazilian green/red chemotypes
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Evidence-Based Benefits

  • LowAdjunct glycemic and lipid control in type 2 diabetes
  • LowReduces inflammatory markers
  • LowOral health adjunct (gingivitis, plaque, chemo-related mucositis)

Insufficient-Evidence Claims

  • UnsupportedGeneral immune “boosting”
  • UnsupportedAntiviral effects
  • UnsupportedGeneral wound healing
Key safety note: Allergy is the defining risk — contact dermatitis is common and anaphylaxis has been reported. Avoid with any bee-product or propolis allergy; additive with glucose-lowering and antiplatelet supplements.

Beet Root

Beta vulgaris — dietary nitrate concentrate (juice, powder, capsule)
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Evidence-Based Benefits

  • MediumLowers blood pressure in people with hypertension
  • MediumImproves endurance exercise performance

Insufficient-Evidence Claims

  • UnsupportedDetoxification and liver-health claims
  • UnsupportedGeneral immune support
Key safety note: Additive blood-pressure drop when combined with BP medication or nitrate drugs. Caution with a history of calcium-oxalate kidney stones. Antiseptic mouthwash blocks the effect entirely.

Biotin

Vitamin B7 / vitamin H — sold as d-biotin
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Evidence-Based Benefits

  • HighCorrects true biotin deficiency (rare)
  • LowBrittle-nail strength

Insufficient-Evidence Claims

  • UnsupportedHair growth in people who are not deficient (2026 review of 10 studies found no consistent benefit)
  • UnsupportedSkin health and energy in healthy people
Key safety note: MAJOR: distorts common lab tests — can falsely mask a heart-attack troponin result or mimic thyroid disease. Tell any clinician ordering bloodwork that you take biotin, and stop it before testing.

Burdock Root

Arctium lappa — gobo, greater burdock
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Evidence-Based Benefits

  • LowAdjunct in knee osteoarthritis (single small trial)

Insufficient-Evidence Claims

  • Unsupported“Blood purifier”, detox, and lymphatic-cleanse claims
  • UnsupportedSkin conditions, diabetes, and general inflammation (no human trials)
Key safety note: Commercial burdock tea has repeatedly been found contaminated with belladonna, causing genuine atropine poisoning. Avoid multi-ingredient “detox” blends; caution with bleeding disorders or Asteraceae (ragweed) allergy.

Coenzyme Q10 (CoQ10)

Ubiquinone / ubiquinol — Kaneka Q10, Kaneka QH, and solubilized/liposomal forms
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Evidence-Based Benefits

  • MediumAdjunct in chronic heart failure (mortality/hospitalization)
  • MediumReduces statin-associated muscle pain
  • MediumMigraine prevention

Insufficient-Evidence Claims

  • UnsupportedFatigue, mood, and fertility support
  • UnsupportedBlood pressure and athletic performance
Key safety note: Can reduce warfarin's anticoagulant effect — INR monitoring needed. Reversible liver-enzyme elevation reported at ≥300 mg/day.

Gokhru-Tribulus

Tribulus terrestris — gokhru, gokshura, puncturevine
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Evidence-Based Benefits

  • LowErectile-function support in men with existing dysfunction

Insufficient-Evidence Claims

  • UnsupportedRaising testosterone (8 of 10 trials in a 2025 review found no effect)
  • UnsupportedMuscle building and athletic performance
Key safety note: Documented case reports of serious liver and kidney injury; also priapism and seizures reported. Avoid in liver/kidney disease and with clopidogrel; common adulterant carrier for undeclared anabolic agents.

Guarana

Paullinia cupana — concentrated caffeine source (3–5% raw, 22–26% extract)
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Evidence-Based Benefits

  • MediumAlertness / subjective energy (tracks its caffeine dose)
  • LowSimple and choice reaction time

Insufficient-Evidence Claims

  • UnsupportedOverall cognition, memory, and accuracy
  • UnsupportedWeight loss and cancer-related fatigue
Key safety note: The main risk is uncounted caffeine — guarana is a common hidden source. Avoid stacking with other caffeine or stimulants; cardiac rhythm disturbances reported at high intake.

Lion's Mane

Hericium erinaceus — yamabushitake, bearded tooth fungus
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Evidence-Based Benefits

  • LowSleep quality, mood, and subjective focus (inconsistent across trials)

Insufficient-Evidence Claims

  • UnsupportedMemory / cognitive enhancement (some trials showed worse recall than placebo)
  • UnsupportedNerve regeneration in humans (shown only in animal models)
  • UnsupportedAlzheimer's or dementia treatment — FDA/FTC have issued warning letters over this claim
Key safety note: No safety data in pregnancy, lactation, or children. Rare allergic reactions and contact dermatitis reported; avoid with known mushroom allergy.

Maca

Lepidium meyenii — Peruvian root, sold as yellow/red/black powder or gelatinized extract
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Evidence-Based Benefits

  • MediumSexual desire and libido (men and women)
  • LowEasing SSRI-induced sexual dysfunction

Insufficient-Evidence Claims

  • UnsupportedMenopause symptom relief (judged insufficient by professional guidelines)
  • UnsupportedEnergy and athletic-performance claims
Key safety note: Unusually reassuring safety record — it's a food crop. Caution with thyroid conditions, especially on a low-iodine diet (goitrogenic in excess).

Magnesium

Sold as bisglycinate/glycinate, citrate, malate, chloride, taurate, L-threonate, oxide
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Evidence-Based Benefits

  • MediumLowers blood pressure in hypertensive or deficient adults
  • MediumImproves glucose and lipid markers in type 2 diabetes
  • LowMigraine prevention (specific citrate form)
  • LowDepression adjunct (small, mostly unblinded trials)

Insufficient-Evidence Claims

  • UnsupportedSleep / insomnia aid (evidence does not support routine use)
  • UnsupportedMuscle-cramp relief (Cochrane review found essentially no effect)
Key safety note: Independent lab testing found many retail “glycinate” products are not chemically what the label claims. Reduces absorption of certain antibiotics and osteoporosis drugs (separate dosing by hours); long-term PPI use can cause magnesium deficiency.

Nitric Oxide (Citrulline & Arginine)

L-citrulline, citrulline malate, and L-arginine
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Evidence-Based Benefits

  • MediumL-citrulline lowers blood pressure
  • MediumL-arginine supports erectile function (esp. with PDE5 inhibitors)
  • LowCitrulline malate for exercise performance

Insufficient-Evidence Claims

  • UnsupportedBroad muscular “pump” / endurance claims beyond narrow tested measures
Key safety note: L-arginine is not recommended after a recent heart attack (mortality signal) and can worsen asthma. Additive blood-pressure drop with BP medication or nitrate drugs.

Olive Oil

Extra virgin olive oil and its concentrated phenolics
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Evidence-Based Benefits

  • MediumProtects LDL cholesterol from oxidative stress (EFSA-authorized claim)
  • MediumReduces cardiovascular and all-cause mortality as a dietary fat replacement

Insufficient-Evidence Claims

  • UnsupportedHDL maintenance (rejected by EFSA in 2025)
  • UnsupportedBlood pressure, anti-inflammatory, respiratory, and GI claims (rejected by EFSA in 2011)
Key safety note: Fraud and adulteration are the dominant risk — look for a harvest date and third-party certification. Calorie-dense at ~120 kcal per tablespoon.

Omega-3 Fish Oil

Marine EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)
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Evidence-Based Benefits

  • HighLowers elevated triglycerides (dose-dependent)
  • MediumSecondary cardiovascular risk reduction (high-risk patients, high doses)
  • MediumAnti-inflammatory support in rheumatoid arthritis
  • MediumFetal and infant neurodevelopment (DHA)

Insufficient-Evidence Claims

  • UnsupportedDepression, cognition, and dry eye at typical consumer doses
Key safety note: A 2025 meta-analysis found increased atrial-fibrillation risk in high-cardiovascular-risk patients above 1,500 mg/day. Interacts with anticoagulants; rancid oil is common — look for peroxide/TOTOX testing.

Rhodiola

Rhodiola rosea — golden root, arctic root (SHR-5, WS 1375 extracts)
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Evidence-Based Benefits

  • MediumShort-term stress- and shift-work-related fatigue
  • MediumEndurance exercise performance and recovery markers

Insufficient-Evidence Claims

  • UnsupportedDepression treatment (underpowered trial, not statistically significant vs. placebo)
Key safety note: A January 2026 market survey found 100-fold variation in potency, likely species substitution, and trace heavy metals in every U.S. product tested — buy a named, tested extract only.

Shilajit

Himalayan mineral resin (asphaltum / mumijo)
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Evidence-Based Benefits

  • LowTestosterone, strength, fertility, and bone-density claims (each from one small, unreplicated trial)

Insufficient-Evidence Claims

  • UnsupportedEnergy / mitochondrial function boost (no human trial support)
  • UnsupportedAltitude-sickness adaptation (no human trial support)
Key safety note: Active contamination concern: a 2025 analysis found thallium levels in some finished products higher than in the raw source material. Avoid unpurified “raw resin”; not for pregnancy, kidney disease, or iron-overload conditions.

Tongkat Ali

Eurycoma longifolia — longjack, Malaysian ginseng, pasak bumi
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Evidence-Based Benefits

  • LowRaises testosterone in men who already have low levels (mostly manufacturer-funded trials)

Insufficient-Evidence Claims

  • UnsupportedTestosterone or muscle-building benefit in men with normal levels
Key safety note: Lead contamination documented in some retail Malaysian products. Avoid in hormone-sensitive cancers, liver or kidney disease; liver-injury signals reported in adverse-event databases.

Vitamin B12

Cobalamin — cyanocobalamin, methylcobalamin, hydroxocobalamin
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Evidence-Based Benefits

  • HighTreats and prevents true B12 deficiency and pernicious anemia
  • HighReverses deficiency-related nerve damage
  • MediumHigh-dose oral matches injections for treating deficiency

Insufficient-Evidence Claims

  • UnsupportedEnergy, mood, cognition, hair, or athletic performance in people who are not deficient — the largest gap between marketing and evidence in the vitamin aisle
Key safety note: One large cohort found high-dose B12 (>55 mcg/day) associated with roughly double the lung-cancer risk in male smokers. Metformin and long-term PPI/acid-reducer use roughly triple the odds of deficiency.

Vitamin C

L-ascorbic acid / ascorbate
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Evidence-Based Benefits

  • HighPrevents and treats true deficiency (scurvy)
  • MediumReduces cold incidence in people under extreme physical stress (athletes, cold exposure)
  • MediumEnhances absorption of non-heme (plant-based) iron
  • LowShortens cold duration with continuous daily dosing

Insufficient-Evidence Claims

  • UnsupportedPreventing colds in the general population (no reduction in incidence)
  • UnsupportedHigh-dose oral cancer treatment (only IV dosing reaches the concentrations studied)
Key safety note: Falsely elevates many glucose-meter readings and can mask a positive fecal occult-blood test. Caution with hemochromatosis or other iron-overload conditions, since it boosts iron absorption.

Vitamin D3

Cholecalciferol
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Evidence-Based Benefits

  • HighCorrects deficiency; prevents rickets and osteomalacia
  • MediumSlows progression from high-risk prediabetes to type 2 diabetes
  • MediumModest all-cause mortality reduction in adults over 75
  • MediumSupports healthy pregnancy outcomes

Insufficient-Evidence Claims

  • UnsupportedFracture and fall prevention, cancer prevention, and cardiovascular event prevention in people who are already replete
  • UnsupportedRespiratory infection prevention in adults (a 2025 meta-analysis of 46 trials found this null)
Key safety note: Don't stack multiple vitamin D sources (multivitamin + fish oil + standalone D3 adds up invisibly). Large monthly bolus doses (24,000–60,000 IU) increased fall risk in a major trial; interacts with thiazide diuretics.

Zinc

Essential trace mineral — gluconate, picolinate, citrate, bisglycinate, oxide
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Evidence-Based Benefits

  • HighCorrects deficiency; supports immune function, wound healing, taste and smell
  • LowShortens common-cold duration (as a lozenge, started within 24 hours)

Insufficient-Evidence Claims

  • UnsupportedPreventing colds (little to no benefit)
  • UnsupportedRaising testosterone in men who are not deficient
Key safety note: More than 40 mg/day long-term can cause copper deficiency (anemia, nerve damage). Never use intranasal zinc products — linked to permanent loss of smell.

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