L-Carnitine

Tier 1 — strong evidence · Male fertility · Cardiac · Fat metabolism · Exercise recovery

An endogenous molecule that shuttles long-chain fatty acids into mitochondria for energy production. For male subfertility, a 2018 meta-analysis of 15 RCTs (Salas-Huetos et al., PMID 30462179) confirmed carnitines increase sperm total motility (+7.84%), progressive motility (+7.45%), and morphology (+4.91%). A 2023 network meta-analysis (Zafar et al., PMID 36943634) further showed L-carnitine combined with micronutrients significantly improves pregnancy rates in men with idiopathic infertility. For cardiac patients, a 2013 JAMA meta-analysis (DiNicolantonio, 13 trials) demonstrated reduced…

Dose: Male fertility: 2-3 g/day in divided doses for 3-6 months. Cardiac support: 2-4 g/day under medical supervision. Athletic performance: 2 g with a carbohydrate-containing meal pre-exercise (insulin drives carnitine into muscle).