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Supplement ScienceSupplementScience

Supplement Ingredient Guide

Evidence-based deep dives into supplement ingredients. Each guide covers benefits, optimal dosage, forms, safety, clinical research, and product recommendations — all reviewed by our editorial team against published research.

We cover 279 supplement ingredients across 20 categories including vitamins, minerals, adaptogens, brain health, gut...

We cover 279 supplement ingredients across 20 categories including vitamins, minerals, adaptogens, brain health, gut health, and more. Each ingredient guide covers benefits, dosage, forms, side effects, research, and FAQs — all citing peer-reviewed clinical trials.

Health Goals
Evidence Strength
Safety Profile

★ Most-Cited Ingredients

Magnesium

Magnesium

Mineral Supplement

Bottom line: For sleep support, magnesium glycinate is usually the most practical first-choice form. Start with 100-200mg elemental magnesium in the evening, adjust only if tolerated, and stay at or below 350mg/day from supplements unless a clinician recommends otherwise.

Strong7 studies cited
Vitamin D3

Vitamin D3

Fat-Soluble Vitamin

Bottom line: Most adults need vitamin D3 supplements — 42% are deficient. Take 1,000-4,000 IU daily with a fatty meal for immune, bone, and mood support.

Strong13 studies cited
Omega-3

Omega-3

Essential Fatty Acid

Bottom line: Omega-3s have strong evidence for heart, brain, and joint health. Take 1,000-2,000mg EPA+DHA daily — choose triglyceride form fish oil or algal oil for vegans.

Strong13 studies cited
Probiotics

Probiotics

Live Microorganisms

Bottom line: Probiotics work, but benefits are strain-specific — not all probiotics do the same thing. Choose strains matched to your health goal at 10-50 billion CFU daily.

Strong11 studies cited
Ashwagandha

Ashwagandha

Adaptogenic Herb

Bottom line: Ashwagandha (KSM-66) is the best-studied adaptogen for stress and anxiety. Take 300-600mg daily — expect noticeable calm within 4-8 weeks.

Strong13 studies cited
Melatonin

Melatonin

Neurohormone

Bottom line: Melatonin works for sleep onset and jet lag, but less is more — start at 0.5mg, not 5mg. It is safe long-term and does not cause dependence.

Strong11 studies cited
Vitamin B12

Vitamin B12

Water-Soluble Vitamin

Bottom line: B12 deficiency is common in vegans, older adults, and metformin users. Take 1,000mcg methylcobalamin daily if at risk — it resolves fatigue and brain fog from deficiency.

Strong13 studies cited
Turmeric / Curcumin

Turmeric / Curcumin

Plant Extract / Polyphenol

Bottom line: Curcumin works as well as ibuprofen for joint pain, but you must use an enhanced-absorption form (Meriva, Longvida, or with piperine). Standard turmeric barely absorbs.

Strong13 studies cited
Coenzyme Q10 (CoQ10)

Coenzyme Q10 (CoQ10)

Coenzyme / Antioxidant

Bottom line: CoQ10 is essential for anyone on statins and has strong evidence for heart health. Take 100-300mg ubiquinol daily — especially important for adults over 40.

Moderate12 studies cited
Collagen

Collagen

Structural Protein

Bottom line: Collagen peptides at 10-15g daily genuinely improve skin elasticity and reduce joint pain. Best for skin aging and osteoarthritis — take with vitamin C for optimal synthesis.

Moderate10 studies cited
Iron

Iron

Essential Trace Mineral

Bottom line: Only supplement iron if blood tests confirm deficiency. Ferrous bisglycinate at 25-45mg daily corrects deficiency with fewer GI side effects than ferrous sulfate.

Strong8 studies cited
5-HTP

5-HTP

Amino Acid

Bottom line: 5-HTP at 100-300 mg/day affects serotonin pathways for mood and sleep support — do not combine with SSRIs/SNRIs/MAOIs or other serotonergic drugs (serotonin syndrome risk).

Moderate11 studies cited

Sleep & Stress

9 more sleep & stress guides are listed in Browse A-Z below.

Brain Health

12 more brain health guides are listed in Browse A-Z below.

Gut Health

13 more gut health guides are listed in Browse A-Z below.

Vitamins

9 more vitamins guides are listed in Browse A-Z below.

Minerals

10 more minerals guides are listed in Browse A-Z below.

Adaptogens

8 more adaptogens guides are listed in Browse A-Z below.

Anti-Inflammatory

10 more anti-inflammatory guides are listed in Browse A-Z below.

Fitness & Recovery

9 more fitness & recovery guides are listed in Browse A-Z below.

Immune Support

17 more immune support guides are listed in Browse A-Z below.

Longevity

11 more longevity guides are listed in Browse A-Z below.

Heart Health

6 more heart health guides are listed in Browse A-Z below.

Joint & Bone Health

2 more joint & bone health guides are listed in Browse A-Z below.

Women's Health

4 more women's health guides are listed in Browse A-Z below.

Men's Health

6 more men's health guides are listed in Browse A-Z below.

Amino Acids

16 more amino acids guides are listed in Browse A-Z below.

Skin & Beauty

3 more skin & beauty guides are listed in Browse A-Z below.

Weight Management

7 more weight management guides are listed in Browse A-Z below.

Eye Health

1 more eye health guides are listed in Browse A-Z below.

Liver & Detox

3 more liver & detox guides are listed in Browse A-Z below.

Hormonal Health

3 more hormonal health guides are listed in Browse A-Z below.

Browse A-Z

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