Caffeine

Caffeine is a naturally occurring methylxanthine alkaloid and the most widely consumed psychoactive substance in the world. Primarily found in the seeds, leaves, and fruits of plants such as coffee (Coffea), tea (Camellia sinensis), and cacao (Theobroma cacao), it functions as a natural pesticide for plants while acting as a potent central nervous system stimulant in humans. In the context of nutrition and longevity, it is increasingly recognized for its role as a delivery vehicle for diverse phytochemicals and antioxidants that support cellular health.

Caffeine primarily works as a non-selective antagonist of adenosine receptors (A1 and A2A). By blocking adenosine—a neurotransmitter that signals tiredness—it prevents the onset of drowsiness and increases the firing of neurons, which triggers the release of other neurotransmitters like dopamine and norepinephrine. Recent 2024-2025 research also highlights that caffeine activates the AMPK (AMP-activated protein kinase) pathway, often called the body's 'metabolic switch.' This activation helps regulate energy balance, reduces neuroinflammation, and promotes telomere length preservation, which is a key marker of biological longevity.

• Daily Intake: Aim for a moderate consumption of 300–400 mg per day (approximately 3–4 cups of brewed coffee) to achieve the greatest reduction in all-cause mortality and cardiometabolic risk (Endocrine Society, 2024).
• Performance Timing: For athletic benefits, consume 3–6 mg/kg of body mass about 60 minutes before physical activity to enhance endurance and reaction time (ISSN guidelines).
• Circadian Protection: To safeguard sleep quality, the final dose of caffeine should be consumed no later than 2:00 PM, or at least 8–10 hours before bed.
• Special Populations: Pregnant individuals should limit intake to under 200 mg daily. Individuals with severe anxiety or cardiac arrhythmias should consult a physician, as sensitivity varies by genotype (CYP1A2 gene).
• Purity: Consume caffeine via black coffee or green tea to avoid the metabolic downsides of added sugars and synthetic creamers, which can negate longevity benefits.