Which Is Better for Immune System Support?

Vitamin C and zinc are nutrients that your immune system needs to help your body fight respiratory infections.

Zinc and Vitamin C Are Both Crucial For Immune System Function

• Both zinc and vitamin C help the cells in your immune system work well and improve your body’s ability to combat viruses and swelling (inflammation).
• Low levels of either zinc or vitamin C reduce your immune system’s ability to fight disease, making it more likely you will get sick.
• Guidelines recommend that adults aim for 75 to 120 milligrams (mg) of vitamin C and 8 to 12 milligrams (mg) of zinc daily, depending on different factors.
• These nutrients can be obtained through the diet or consumed as dietary supplements.
• Boost your vitamin C intake with citrus fruits and vegetables, and your zinc levels by eating red meat and seafood.

Vitamin C May Work Better Than Zinc for Preventing Respiratory Viruses

• Vitamin C may lower your risk of catching a cold, particularly if you are an older adult, live in an extremely cold climate, exercise strenuously, or smoke cigarettes.
• Zinc is unlikely to prevent the common cold or COVID-19.
• Zinc lowers the risk of lung infection (pneumonia) in children who don’t consume enough zinc in their diet.

Zinc Is Better For Shortening How Long Colds Last

• Zinc shortens the duration of a cold by approximately two days if taken at the first sign of symptoms. Keep in mind, though, that zinc supplements do not make symptoms of the common cold (such as runny nose, sneezing, cough, and fatigue) any less severe.
• There’s some evidence that zinc can also shorten the length of COVID-19 and make the disease milder. People with COVID-19 who take zinc are less likely to be admitted to the intensive care unit (ICU) or to die from the disease.
• Taking vitamin C regularly may make your colds a little shorter (usually less than a day) and your symptoms less severe. However, waiting to start vitamin C until you have cold symptoms is unlikely to be beneficial.
• There’s not enough evidence to routinely recommend vitamin C to treat COVID-19.

Zinc Has More Long-Term Term Risks

• High doses of either vitamin C or zinc can cause gastrointestinal side effects, including stomach pain, nausea, diarrhea, or vomiting. Zinc can also cause a metallic taste.
• Vitamin C dissolves in water. This means that in healthy individuals, any excess vitamin C consumed is eliminated from the body through urine. Rarely, taking too much vitamin C may cause kidney stones.
• Long-term use of zinc supplements or topical products that contain zinc can cause serious side effects. These include low levels of copper, low blood cell count, weakened immune system, and nervous system problems.

How Much Should I Take?

• To prevent colds, take 200 mg to 2 grams (g) of vitamin C daily. Consider increasing your intake of foods rich in vitamin C or taking a daily supplement during the winter months.
• To shorten the duration of a cold, start taking zinc daily within 24 hours of the onset of symptoms.
• Zinc has been studied at dosages of 45 to 300 mg daily for up to 2 weeks. However, further research is needed to determine the optimal dose.
• Be sure to discuss any supplements you take and how you take them with your healthcare provider for optimal safety.