Vitamin a

Men's Fitness, August, 2005

Add vitamin A to the list of supplements you should take when you feel a cold coming on. According to a new Penn State study, the nutrient may help make an immune-system booster called interferon--which is produced naturally by the body--more effective at fighting off bugs and serious disease (including multiple sclerosis and arthritis).

Although you can get vitamin A in a standard multi, it's just as easy to load up at mealtime. Sweet potatoes, carrots, mangoes, and spinach are all good sources.