Myths and truths about vitamin C

Vitamin C, also known as ascorbic acid, is a powerful micronutrient that plays a key role in keeping your body healthy. Here we'll explore some myths and truths about this vital micronutrient.

What does vitamin C do in the body?

Vitamin C is an essential micronutrient, important to many functions in the body. Vitamin C plays a key role in creating collagen, a protein essential for maintaining healthy skin, tendons, ligaments, and blood vessels, as well as for repairing wounds and forming scar tissue. The vitamin also helps maintain strong bones, cartilage, and teeth. In addition, it boosts the body's ability to absorb iron from plant-based foods.

Vitamin C plays a key role in supporting the immune system. A powerful antioxidant, vitamin C neutralizes free radicals — unstable molecules that can damage cells and contribute to aging and diseases like cancer and heart disease. The micronutrient is also involved in producing neurotransmitters that help nerve cells communicate.

How much vitamin C do you need?

The human body cannot make vitamin C, so it must be obtained through a person's diet or from supplements.

The amount of vitamin C you need each day depends on your age, sex, and life stage.

You may need more or less vitamin C depending on specific health conditions or lifestyle factors.

Dangers of too much vitamin C

Vitamin C is generally safe. But taking too much — more than 2,000 milligrams (mg) per day — can cause unpleasant side effects due to the body's inability to absorb excessive amounts. Common issues include diarrhea, nausea, and stomach cramps.

Rarely, high doses of vitamin C may contribute to kidney stones, especially in individuals with kidney disorders. Excessive supplementation during pregnancy can affect a baby's vitamin C levels after birth. There are also concerns about high vitamin C intake in individuals with specific health conditions, such as iron overload disorder or hereditary hemochromatosis.

Can vitamin C prevent colds or shorten the duration of colds?

The idea that vitamin C can prevent colds became popular in the 1970s, but research has largely debunked this myth. While taking vitamin C regularly doesn't appear to reduce the chances of catching a cold, some evidence suggests it might slightly shorten the duration of a cold or lessen the severity of cold symptoms.

For most people, maintaining a balanced diet with adequate vitamin C is sufficient to keep the immune system healthy without taking high-dose supplements.

Does vitamin C reduce the risk of high blood pressure and heart disease?

The relationship between vitamin C and heart health remains unclear. Some large observational studies suggest that higher intakes of vitamin C — especially from fruits and vegetables — may be associated with a reduced risk of cardiovascular disease and stroke, likely due to its antioxidant properties, which protect blood vessels and reduce plaque buildup.

However, clinical trials testing vitamin C supplements have not shown consistent benefits in preventing or reducing heart disease. While some evidence points to a protective effect, other studies do not.

As a result, there is no specific recommendation to take more than the daily recommended amount of vitamin C for heart health.

What are some health benefits of vitamin C?

Vitamin C offers some probable health benefits, while others are less certain. For example:

• Immune function. As an antioxidant, vitamin C supports the immune system by protecting cells from free radical damage and enhancing the body's natural defenses.

• Eye health. Vitamin C is included in the dietary supplement that was shown in the Age-Related Eye Disease Study (AREDS) trials to prevent progression of age-related macular degeneration (AMD) to its most damaging form. But taking vitamin C supplements has not been demonstrated to lower the chance of developing AMD overall. Higher dietary intake of vitamin C is linked to a reduced risk of cataracts. However, vitamin C supplement use has shown mixed results, with some studies even suggesting an increased risk of cataracts at high doses.
• Cancer. Epidemiological studies have shown diets that include lots of fruits and vegetables are associated with a lower risk of several cancers. This may be due, in part, to the foods' vitamin C content. However, studies on vitamin C supplementation alone have not consistently shown a reduced cancer risk.
• Cardiovascular health. Vitamin C supplements might have a modest effect on blood pressure. But clinical trials of vitamin C supplements have largely failed to demonstrate significant benefits in preventing or reducing cardiovascular events.
• General antioxidant benefits. As a key antioxidant, vitamin C neutralizes free radicals, slowing down oxidative stress that contributes to aging and various chronic diseases, such as arthritis and neurodegenerative conditions.

Good food sources of vitamin C

Vitamin C is abundant in many fruits and vegetables, making it easy to meet your daily requirements through a balanced diet.

Fruits high in vitamin C:

• citrus fruits: oranges, grapefruits, lemons, and limes
• berries: strawberries, raspberries, blueberries, and cranberries
• tropical fruits: kiwi, mango, papaya, and pineapple
• melons: cantaloupe and watermelon
• tomatoes.

Vegetables rich in vitamin C:

• cruciferous vegetables: broccoli, Brussels sprouts, and cauliflower
• peppers: green and red bell peppers
• leafy greens: spinach, cabbage, turnip greens, and other leafy vegetables
• root vegetables: sweet potatoes and white potatoes
• winter squash.

Some cereals, beverages, and processed foods are fortified with vitamin C.

Tips for maximizing vitamin C in your diet

A few simple facts can help you get even more vitamin C from your diet.

• • Vitamin C content is highest in fresh, raw fruits and vegetables.
  • Cooking, especially boiling, can reduce vitamin C levels. Opt for steaming or microwaving to minimize nutrient loss.
  • Prolonged storage and exposure to light can degrade vitamin C.