Mar 23, 2026 12:00:00
Vitamin C is a very well-known essential nutrient, abundant in vegetables and fruits, and also added to various supplements and beverages. Professor Neil Wheat, a professor in the Department of Natural Sciences at Macquarie University in Australia, and his colleagues have explained whether vitamin C intake is helpful in preventing colds, lowering blood pressure, and reducing cancer risk.
Should I take vitamin C to ward off colds, lower blood pressure or reduce cancer risk?
https://theconversation.com/should-i-take-vitamin-c-to-ward-off-colds-lower-blood-pressure-or-reduce-cancer-risk-277963
Vitamin C is one of the most iconic nutrients in health-conscious culture. Wheat explains that vitamin C is a powerful antioxidant that protects cells from damage, supports the body’s immune function, helps with iron absorption, and is also involved in wound healing.
Vitamin C helps bind body tissues together and is also involved in the synthesis of collagen , a structural component of gums and skin. A severe deficiency of vitamin C can lead to scurvy , where the body cannot produce enough collagen, making it impossible to bind tissues together. Ultimately, this can result in tooth loss and ruptured blood vessels causing internal bleeding.
Humans cannot synthesize vitamin C, so they must obtain the vitamin C their bodies need from food and drinks. It is said that humans obtain the majority of their vitamin C from vegetables (about 40%), fruits (about 19%), and vegetable and fruit juices (about 29%).
Because vitamin C in supplements and vitamin C in food are chemically identical, the human body does not distinguish between the two. However, Wheat et al. explained that food contains other substances such as dietary fiber, flavonoids , vitamins, and minerals, and these substances can create synergistic effects with vitamin C, resulting in health benefits that cannot be obtained from vitamin C alone.
Wheat and his colleagues explain whether vitamin C actually reduces the risk of health problems such as ‘colds,’ ‘heart disease and stroke,’ and ‘cancer,’ for which vitamin C is said to be helpful.
◆Cold
Vitamin C is widely believed to boost immunity and therefore be effective in preventing and treating colds and the flu. However, a 2013
paper reviewing various research findings revealed that regularly taking more than 200 mg of vitamin C does not reduce the incidence of colds. On the other hand, it has been shown that regular intake of vitamin C can shorten the duration of a cold, and high doses of 1000 mg or more can alleviate symptoms.
However, when vitamin C is used to treat the common cold, taking it in the early stages of symptoms did not affect the duration or severity of the cold. Some studies showed a slight effect when taken daily before catching a cold, but the authors concluded that regular intake of vitamin C is not very effective in preventing colds.
◆ Heart disease and stroke
A 2017 study showed that taking vitamin C supplements did not change the risk of cardiovascular diseases such as heart attack, stroke, and angina. One study suggested that taking more than 200 mg of vitamin C per day may lower systolic blood pressure by 4 mmHg and diastolic blood pressure by 2 mmHg, but this effect is comparable to that of normal aerobic exercise and does not match the effects of conventional drug therapy.
◆Cancer
Multiple studies have shown that vitamin C does not prevent cancers such as gastrointestinal cancer , lung cancer , breast cancer, prostate cancer, and colorectal cancer .
The recommended daily intake of vitamin C for adults is 100 mg , with an upper limit of 2000 mg per day. Although vitamin C is water-soluble and does not accumulate in the body, excessive intake can cause diarrhea and nausea, and in men, it can increase the risk of kidney stones.
Wheat and colleagues stated, ‘Most people don’t need vitamin C supplements. A balanced diet provides sufficient amounts from foods such as citrus fruits, berries, tomatoes, bell peppers, broccoli, and kale.’
