Convert vitamins A, E, and K between metric units (mcg/mg) and International Units (IU). Each vitamin has its own conversion factor, and vitamin E differs by form. For vitamin D, see our dedicated D converter. Why IU vs mcg matters: The 2020 FDA Nutrition Facts label moved from IU to mcg/mg as primary, but older […]

Calculate spermidine dose by goal — autophagy / longevity, cognitive support, hair growth. Trial doses range from 1.2 mg (food intake) to 6 mg (supplement protocols). Wheat germ is the cheapest natural source; branded supplements offer convenience at premium price. Math, not medical advice. Honest caveat: spermidine human RCT evidence is preliminary. SmartAge trial (Schwarz

Calculate trans-resveratrol dose. Stilbene polyphenol found in red wine, grapes, Japanese knotweed (the standard supplement source). 2010s hype was excessive — early sirtuin-activation claims were oversold; David Sinclair-era enthusiasm has moderated. Real but modest CV / metabolic effects in some populations. Math, not medical advice. Honest framing: trans-resveratrol has real biological activity but effect sizes

Calculate quercetin dose by goal. Flavonoid found in onions, apples, capers. Three main use cases: allergies (mast cell stabilizer), senolytic protocols (with fisetin or dasatinib), cardiovascular / anti-inflammatory. Absorption is poor — form matters. Math, not medical advice. Bioavailability problem: standard quercetin (quercetin dihydrate) absorbs poorly — under 5% from a typical oral dose. Phytosome

Calculate a personalized pre-workout stack: caffeine + L-theanine + creatine + beta-alanine + citrulline. Each component has strong evidence individually. Scales caffeine to body weight, applies the 1:2 caffeine:theanine smoothing ratio, and warns about beta-alanine paresthesia. Math, not medical advice. Why a custom stack beats commercial pre-workout: commercial pre-workouts hide ingredient amounts in “proprietary blends”

Calculate NMN (nicotinamide mononucleotide) or NR (nicotinamide riboside) dose. Both are NAD+ precursors. NR (Niagen) has GRAS status + Chromadex commercial protection. NMN had FDA reclassification action in 2022 (status remains debated). Honest framing on longevity evidence. Math, not medical advice. Regulatory and evidence reality check: NMN was effectively reclassified by FDA in 2022 as

Calculate N-acetylcysteine (NAC) dose by goal — liver support, cognitive, PCOS, mucolytic. RCT doses range from 600 mg to 2.4 g/day. The FDA-approved hospital protocol for paracetamol overdose is much higher (and requires immediate medical care). Math, not medical advice. Important: if you’ve taken a paracetamol/acetaminophen overdose, oral NAC supplements are NOT a substitute for

Calculate lion’s mane (Hericium erinaceus) dose by goal. RCT doses range from 750 mg to 3.2 g/day depending on goal and form. Fruiting body extract delivers ~3-4× the active hericenones per gram vs mycelium-on-grain. Math, not medical advice. The fruiting body vs mycelium trap: most “lion’s mane capsules” on Amazon are mycelium grown on grain

Calculate L-theanine dose by goal — caffeine smoothing (1:2 caffeine:theanine), pre-sleep calm, anxiety. Trial doses 100-400 mg/day. The “caffeine ratio” rule is the most evidence-supported use case. Math, not medical advice. The 100mg caffeine + 200mg theanine combo is the famous “Nootropic stack” backed by Owen 2008 + Haskell 2008 — combination produced better attention/alertness

Calculate an evidence-based immune stack: zinc + vitamin C + vitamin D + elderberry + quercetin by goal. Distinguishes chronic prevention (low daily doses), acute illness (loading doses), post-exposure (high doses for 5-7 days). Math, not medical advice. Honest framing: none of these supplements PREVENT infection in healthy, well-nourished adults with strong evidence. They may