EVIDENCE GUIDE

Nutrition and Normal Immune Function

Adequate intake of vitamins and minerals—including vitamins A, C, D and E, selenium and zinc—is important for normal immune function. NIH also cautions that, in the absence of deficiency, routine micronutrient supplementation probably does little to prevent or treat specific infections.

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.