As with any supplement, be sure to talk to your doctor about any potential interactions that vitamin C may have with any medications that you’re presently taking, or any underlying medical conditions, including kidney stones.

Zinc

Zinc may be one of the most critical minerals for the body’s overall immune function. Getting the right dosage has been shown to reduce the duration of cold and flu bugs, which is why zinc lozenges are so popular among consumers to battle colds. A number of studies have shown that taking zinc gluconate or acetate lozenges every two hours within the first two days of a cold can decrease its duration by a day or more. Unfortunately there isn’t much evidence to show that taking zinc preventatively will keep you from catching a cold.

These lozenges should always be taken on a full stomach because there is a risk that they will make you nauseated. Studies seem to show that lozenges containing between 9 and 24 milligrams of zinc are most effective.

Garlic

Garlic, whether consumed raw or in a powdered supplement form, may be the ingredient with scientific evidence backing its value in keeping illness at bay. In a British study, volunteers who took a garlic supplements for 12 weeks during cold season were “far less likely” to get sick than those who took placebos. There were 24 reported cases of colds in the group that was given garlic supplements, as opposed to 65 in the placebo group. And the garlic not only showed benefit at preventing the onset of illness - but those in the garlic group who came down with illnesses recovered on average about four days sooner than those people in the placebo group.