By Pat Kendall, Ph.D., R.D.
Food Science and Human Nutrition Specialist
Colorado State University Cooperative Extension
Achoo! It's that time of year again. Everywhere you turn, someone is coughing or sneezing.
If you're one of the unlucky ones coming down with or dealing with a common cold, you may be wondering how best to treat your symptoms. Are over-the-counter cold medications the only way to go, or do alternative remedies such as vitamin C, echinacea and zinc really help? Here's what we've learned from studies on the subject.
Vitamin C: Vitamin C has long been touted for its ability to prevent and cure the common cold. Although these claims have been blown out of proportion, an adequate intake of vitamin C is necessary to help fight infections and keep the immune system healthy. Furthermore, some research shows that taking extra vitamin C at the onset of a cold may cause a mild antihistamine effect, possibly reducing the intensity of your symptoms and shortening the duration of the cold.
The recommended dietary allowance, or RDA, for vitamin C is 75 milligrams per day for women and 90 milligrams for men. Although no specific, magic dosage of vitamin C has been shown to be optimal for treating cold symptoms, megadoses--more than 2,000 mg per day--can actually do more harm than good. In some instances, taking large amounts of vitamin C can cause side effects such as nausea, abdominal cramps and diarrhea.
Echinacea: Over the past several years, echinacea has become one of the hottest herbal remedies in the United States. While little research has been done in the United States, a 2001 German study found echinacea was effective in alleviating symptoms more rapidly than placebos in patients with common colds. However, another recent German study published in the "American Journal of Medicine" concluded that treating patients with echinacea did not significantly decrease the incidence, duration or severity of colds and respiratory infections.
Echinacea appears to have few side effects when used by basically healthy people on an occasional, short-term basis. Since possible adverse effects from long-term use have not been studied, most sources recommend that echinacea only be taken when symptoms of a cold first appear and then only for a week or two. Because echinacea is an immune-system stimulant, people with autoimmune diseases like lupus, multiple sclerosis and rheumatoid arthritis should not take the herb. It is also not recommended for pregnant or lactating women or for people taking corticosteroids and other immunosuppressants.
Zinc: Another alternative cold remedy is the use of zinc lozenges to help reduce the duration and severity of cold symptoms. Thus far, the research on zinc's effectiveness has been contradictory.
A 2000 study published in "Annals of Internal Medicine" looked at the effect of zinc lozenges on the duration of symptoms from the common cold. Those who took a zinc lozenge every two to three hours while awake had colds that lasted approximately four days, while those taking the placebo had colds for eight days. Likewise, a 1998 review of published, randomized controlled trials also concluded that zinc lozenges were effective in treating the common cold. Yet, a U.S. clinically controlled trial published in 2000 in "Clinical and Infectious Diseases" found zinc lozenges did not help reduce the length or severity of cold symptoms among study participants when compared to people receiving a placebo. It has been suggested that the different results may be due in part to differences in zinc ion availability in the various lozenge preparations used.
If you choose to take zinc to try to alleviate cold symptoms, you should be aware that, while a zinc deficiency can depress immune function, so can taking too much zinc. The RDA for zinc is 12 mg per day for adult women and 15 mg per day for adult men. Most experts recommend taking no more than 100 mg of zinc over the course of a day.
The bottom line is that additional research is still needed to learn more about these alternative remedies ant their effectiveness in fighting the common cold. While there is probably no harm in taking moderate doses when you feel a cold coming on, consult your health care provider if your symptoms persist.