Vitamin C is a water-soluble vitamin known for its role in supporting the immune system. It acts as an antioxidant, protecting your cells against damage, and helps strengthen your skin barrier, allowing it to keep out harmful microbes.
Some studies have shown that vitamin C can help prevent or reduce symptoms of cold or flu-like symptoms. However, not all studies show these benefits.
Some studies report that vitamin C can reduce the length of cold or flu-like symptoms by about 10-30%. However, these benefits were mostly seen in people with severe symptoms rather than those with milder symptoms.
Vitamin C supplementation may shorten the duration of a cold by increasing the body’s ability to resist bacteria that can worsen or lengthen colds. It also boosts your immune system to help fight the bacteria or virus causing the cold.
People who take vitamin C supplements regularly may experience milder symptoms when they have a cold compared to people who don’t take vitamin C. Some studies suggest that vitamin C may help reduce the severity of a common cold by about 15%.
Vitamin C may help reduce symptom severity because it has an antihistamine effect, which can help relieve sneezing and a runny nose.
People who engage in strenuous physical activities, such as professional athletes, especially in extremely cold temperatures, may benefit from taking vitamin C for colds.
One study found the risk of developing colds dropped by about 50% in people who took vitamin C two to three weeks before these activities. However, there is not enough evidence to support this benefit in people who engage in more moderate activity.
While there are some benefits in taking vitamin C for colds, current research suggests it only helps when you take it before your cold symptoms start. Taking it after a cold starts likely won’t have an effect on your cold.
Other limitations of taking vitamin C for a cold include:
- Side effects: Vitamin C may have some side effects, especially with high doses, such as diarrhea, nausea, and stomach upset.
- Drug interactions: Vitamin C may interact with certain medications, such as statins (e.g., Zocor) and cancer treatments.
To make the most of your vitamin C for a cold, keep these tips in mind:
- Eat more fruits and vegetables in a variety of colors, such as red bell peppers, citrus fruits, strawberries, and broccoli. Consuming up to five servings of fruits and vegetables can provide as much as 250 milligrams of vitamin C.
- Choose raw fruits and vegetables for the highest vitamin C content. For example, half a cup of raw red bell pepper contains up to 95 milligrams of vitamin C.
- Opt for steaming or microwaving your fruits and vegetables instead of cooking or boiling to reduce nutrient loss.
- Prolonged storage can reduce the strength of vitamin C.
- Avoid storing your vitamin C supplements near sunlight or in areas with high moisture, as this can cause the vitamin to break down and become less effective.
Dosage
While there are no exact recommendations for the vitamin C dose needed to boost the immune system, clinical trials have used doses higher than 1,000 milligrams. This is significantly higher than the recommended daily amount of vitamin C, which is about 90 milligrams for adult men and 75 milligrams for adult women. However, doses up to 2,000 milligrams daily from both fruits and supplements have been used safely.
Consult your doctor before using high doses of vitamin C if you have other health concerns, especially if you have iron absorption issues.
