Immunity & Vitamin C

The primer

Vitamin C, zinc and vitamin D are the three nutrients with the clearest role in normal immune function. Vitamin C is water-soluble and the body absorbs less as the dose per intake rises — 1000 mg in one shot is largely excreted, so split doses (250–500 mg twice daily) work better than a mega-dose. Zinc lozenges (as zinc acetate or gluconate, 75–100 mg total daily in divided doses) may modestly shorten cold duration when started within 24 hours of symptoms — but long-term high-dose zinc is not safe. Elderberry has modest evidence for shortening upper-respiratory symptoms; Sambucol is the most-studied brand. Vitamin D deficiency is linked to poorer immune function and is common in the UAE (see the vitamin D category). Beyond supplements, sleep quality is arguably the highest-leverage immune intervention — repeated poor sleep measurably impairs immune response.