Vitamin C is an essential nutrient crucial for numerous bodily functions, including the repair of body tissues and the maintenance of a healthy immune system. While the human body requires it, it cannot produce vitamin C naturally.
Therefore, consuming foods rich in the vitamin—such as broccoli, Brussels sprouts, strawberries, bell peppers, and tomatoes—is vital for overall health.
Some individuals have opted for vitamin C supplements, which could offer benefits but also carry certain risks.
To better understand the effects of daily vitamin C intake, Sean Marchese, a registered nurse at the Mesothelioma Center with over 15 years of direct patient care experience and a background in oncology clinical trials, outlined its impacts in an interview with the health publication Eat This, Not That.
Antioxidant effects
Marchese explained that vitamin C is a powerful antioxidant that neutralises harmful molecules known as free radicals, which cause oxidative stress—a process linked to chronic inflammation following injury or infection.
A daily dose of vitamin C may also support the production of other antioxidants, including vitamin E and tetrahydrobiopterin, further strengthening the body’s natural defences.
Supports immune system
Vitamin C plays a key role in supporting the immune system by enhancing the function of immune cells such as macrophages and neutrophils. Marchese notes that vitamin C helps the body fight infections, destroy harmful substances, and reduce the impact of disease.
However, he cautioned that it should be viewed as a complement, not a substitute, to vaccines and a nutrient-rich diet. Furthermore, vitamin C assists in clearing out dead immune cells post-infection, preventing damage caused by immune system byproducts.
Potential role in cancer prevention
While most healthy individuals do not require vitamin C supplements, Marchese stated that they may reduce the risk of certain cancers in those who are deficient.
Vitamin C can also be beneficial for cancer patients undergoing treatment who may experience nutrient absorption issues or inflammation. Some evidence suggests that vitamin C supplementation may help lower the risk of pancreatic, oesophageal, and prostate cancers.
May lower risk of eye diseases
Marchese pointed to research showing that, when taken alongside other essential vitamins and minerals, vitamin C supplements may reduce the risk of age-related eye conditions such as macular degeneration and cataracts.
Although vitamin C cannot reverse existing eye damage, it may help slow the decline in visual acuity associated with ageing.
Risks and Side Effects
Marchese warned that vitamin C supplements are not suitable for everyone. High daily doses have been associated with a 20% increased risk of kidney stones compared to those who consume less than the recommended daily amount of 90 mg.
Risk of drug interactions
While generally considered safe, excessive vitamin C can accumulate in the body and cause side effects such as stomach cramps, vomiting, heartburn, and diarrhoea.
Marchese also highlights that high vitamin C levels can interact adversely with certain medications, including:
While vitamin C offerd a wide range of health benefits, including immune support and antioxidant protection, it should be taken responsibly—ideally under medical guidance—to avoid potential risks.
