EVIDENCE GUIDE

Vitamin C and Immune Function

Vitamin C is an essential nutrient and antioxidant involved in healthy immune function. NIH notes that regular vitamin C supplementation may modestly reduce the duration or symptoms of the common cold for some people, while starting it only after a cold begins may not be helpful. Evidence and needs differ by person.

What to keep in perspective

Research about an ingredient or lifestyle factor does not automatically prove that a branded supplement containing it is effective. Dose, formulation, study population and the outcome measured all matter.

Practical takeaway

Start with adequate nutrition and general health habits. If you are considering supplements because of symptoms, a suspected deficiency, medication use or a medical condition, individualized professional advice can be more useful than generalized marketing.