Human Biology and Health Claims

Ask what the claim implies about the body's actual machinery, then ask what evidence would have to exist for it to be true.

Digestion hydrolyses collagen into amino acids (glycine, proline, hydroxyproline). New skin collagen depends on fibroblast activity and signalling, not on where the amino acids came from.

Blood pH is buffered at 7.35–7.45 by bicarbonate, respiration, and the kidneys; stomach acid (pH ~1.5–3) neutralises the water in seconds. Only urine pH changes.

Cytochrome P450 enzymes oxidise lipophilic compounds and phase II enzymes conjugate them for excretion. A juice cleanse adds no enzymes; real liver failure means jaundice and hospital.

Heme iron absorbs better than non-heme; vitamin C reduces Fe³⁺ to absorbable Fe²⁺; fat-soluble vitamins A, D, E, K need dietary fat and can build to toxicity, while excess vitamin C is excreted.

Innate: fast, generic — barriers, complement, macrophages/neutrophils using pattern-recognition receptors. Adaptive: slow, specific — B cells (antibodies) and T cells with randomly generated receptor repertoires, producing memory.

Randomly generated receptors undergo mutation and selection in germinal centres, so receptors that bind the actual pathogen are amplified.

It shows the adaptive system a harmless piece of a pathogen (inactivated virus, surface protein, or mRNA instructions) so memory cells form without surviving the disease.

Globally amplified immunity causes autoimmunity, allergy, or cytokine storms. Better-targeted, not bigger, is the aim.

Adequate sleep, protein and micronutrients (zinc, vitamin D, vitamin A), not smoking, managing chronic stress, and vaccination — correcting deficiency helps, stacking supplements on sufficiency does not because enzymes and receptors saturate.