Vitamin C is a popular supplement, often credited with preventing colds, boosting immunity, and even fighting serious diseases. But while it's essential for our bodies to function, its benefits are often misunderstood or overstated. Before you stock up on supplements, here's what to consider. Vitamin C is a powerful antioxidant, protecting cells from damage. It supports the immune functions of the body, aids in the absorption of iron, and is involved in wound healing. Vitamin C also helps in the synthesis of collagen, which holds together tissues and is a structural component of gums and skin. A severe deficiency of vitamin C leads to a health condition called scurvy, where the body produces insufficient collagen and can’t hold tissue together. Eventually, the gums cannot hold onto teeth and they fall out, and blood vessels break down, causing internal bleeding. Humans cannot synthesize vitamin C. We must take it in through our diet. Most of our vitamin C comes from vegetables (about 40%), fruits (19%), and from vegetable or fruit juices (29%). Chemically, the vitamin C in supplements is identical to the vitamin C in food. However, the supplement form lacks the fibre, flavonoids, other vitamins, minerals, and phytochemicals that come with food, and that may work together with vitamin C. These other compounds help with absorption, provide complementary antioxidants, and together with vitamin C, provide health benefits that the vitamin by itself does not. Historically, sailors often had a very limited diet and were often struck down with scurvy. But if you have a balanced diet, you don’t need vitamin C supplements. Vitamin C has been promoted as a way to boost the immune system. It’s widely considered as a way to prevent and treat the common cold and flu. However, results from a review of all the evidence have shown regular supplementation of 200 mg or more of vitamin C does not reduce the incidence of the common cold. Regular vitamin C supplementation does reduce the duration, and at doses greater than 1,000 mg or more, could reduce the severity of common cold symptoms. When vitamin C is used for treating common colds and only taken at the start of cold symptoms, it does not affect the duration and severity. Some studies have shown very limited benefit when taken daily before getting sick, but the benefit was very small. Overall, the authors concluded that routine supplementation with vitamin C is not worthwhile. Research has shown vitamin C supplementation does not change the risk of a range of cardiovascular diseases including heart attack, stroke, or angina. One study found that vitamin C supplementation at more than 200 mg daily may lower systolic blood pressure by around 4 mmHg and diastolic blood pressure by around 2 mmHg. These are very small changes. These effects are comparable to regular aerobic exercise and may not be clinically meaningful compared to treatment with conventional medicine, which generally lowers systolic blood pressure by at least 12 mmHg. There are consistent results from multiple studies that show vitamin C supplementation is unable to prevent cancer, including for gastrointestinal, lung, breast, prostate, and colorectal cancers. The Recommended Daily Intake (RDI) of vitamin C for adults is 45 mg per day. You can get that from a single small glass of orange juice. The tolerable upper intake level of vitamin C is 2,000 mg daily for adults. Vitamin C is water-soluble and gets excreted in urine, so the body cannot store it. This means mega-dosing does not provide any benefit, and may in fact cause health problems. At high doses (above 2,000 mg daily), vitamin C may cause mild to serious side effects. Too much is known to cause diarrhoea, nausea, and abdominal cramps. It can also contribute to the formation of kidney stones in men, but not women. For people who have chronic kidney disease, vitamin C can be especially problematic because vitamin C is flushed from the body by the kidneys. But when the kidneys don’t work properly, it can build up and cause kidney stones. For most people, a vitamin C tablet is unnecessary. You will get enough from a good balanced diet, from foods such as citrus fruits, berries, tomatoes, capsicum, broccoli, and kale. The evidence doesn’t support claims that vitamin C supplements prevent colds, heart disease, or cancer. In fact, the risks may outweigh the benefits. Personally, I think the hype around vitamin C supplements is often overblown. While vitamin C is essential for our bodies to function, the idea that it can prevent serious diseases or boost immunity significantly is not supported by the evidence. A balanced diet provides all the vitamin C we need, and the risks of taking supplements may outweigh the benefits. From my perspective, it's better to focus on a healthy diet and lifestyle to support our immune system and overall health.
