Spend any winter in Portugal and you'll hear it from the older generation: keep away from the "correntes de ar" — those sneaky air draughts that will "apanhar o peito" (catch your chest) and leave you sniffling for weeks. It sounds like classic folklore, the same family of beliefs as going out with wet hair guarantees a cold. But a doctor writing in Portugal Resident points out that the science is more interesting — and more forgiving of grandma — than you'd expect.
Colds are caused by viruses, full stop. Rhinoviruses account for over half of them, with coronaviruses, RSV and parainfluenza viruses making up most of the rest. Being cold can't create a virus, so a draught can't literally give you a cold. Yet chilling the body does matter. Severe hypothermia (core temperature below 34°C) suppresses the immune system broadly, and even a mild drop in temperature in your nose and throat triggers vasoconstriction — reduced blood flow to those tissues. That slows down the natural killer cells racing to the site of infection, giving respiratory viruses an unopposed window to replicate. Dr Lilly Immergluck of the Morehouse School of Medicine in Atlanta sums it up: if your body is already fighting a cold, the added stress of trying to stay warm can stretch out recovery.
What about supplements? Meta-analyses haven't shown that vitamin C or zinc prevent colds outright, though both support healthy skin and tissue — the body's physical barrier against pathogens — plus antioxidant defences. Vitamin D has the stronger case as an immune modulator, tamping down excessive inflammation and supporting immune cell production, but only as prevention; once you're ill, it does nothing. Prevention beats cure here.
And when illness does land, the classic remedies hold up surprisingly well. Hydration and fever control come first, then chicken soup — "grandma's penicillin". A 2000 study from the University of Nebraska Medical Center found that the standard ingredients (onions, parsnips, celery, parsley, turnips, carrots and chicken) had measurable anti-inflammatory effects and influenced mucus production, genuinely easing symptoms. Soup also helps with thermoregulation and fluids, so it's doing triple duty.
Eastern European households add onion syrup to the arsenal, a tradition centuries old. Onions carry quercetin, a flavonoid antioxidant that blocks inflammatory pathways and calms irritated respiratory tissue, plus organosulfur compounds with natural antimicrobial properties. The author admits to drinking it growing up even when perfectly healthy — which tells you something about how these remedies become family ritual.
So should travellers care? Anyone wintering in Portugal, or renting an old casa with letterbox draughts and stone floors, now knows the locals' warnings carry a kernel of immunology. Pack a scarf, close the windows, top up vitamin D before the season, and if a cold finds you anyway — a big pot of proper chicken soup is not just comfort, it's evidence-based.
