Which food comes to mind first when you think of vitamin C? Lemons? Oranges? Although both citrus fruits are good sources of vitamin C, they are actually in the middle of the ranking of foods richest in vitamin C. “It is often underestimated that vegetables contain the most vitamin C. First and foremost: peppers. Just one covers the average daily requirement of an adult,” says Dr Anne Gürtler, dermatologist and nutritionist from Munich. She adds, “Broccoli, Brussels sprouts and currants are also particularly rich in vitamin C.”
How much vitamin C does the body need and why?
“Vitamin C requirements are often overestimated,” says Dr Gürtler, pointing out that the DGE (German Nutrition Society) recommends an average of 100 milligrams, with women needing a little less than men although the requirement increases for pregnant and breastfeeding women. The same applies to smokers. “Because they have such high oxidative stress due to nicotine, you can add another 40-50 milligrams per day on top,” she says.
Speaking of oxidative stress, vitamin C is an antioxidant. “This means that it neutralises free radicals in the body, protects the cells from damage and thus, counteracts inflammatory processes and premature (skin) ageing,” says Dr Gürtler. “Put simply, vitamin C releases an electron to aggressive molecules, which in turn lack an electron – thereby rendering them harmless.”
“In addition, vitamin C is essential for cell proliferation and cell differentiation, processes that are also central to the health and regeneration of the skin. Furthermore, recent studies in cancer biology indicate that vitamin C has modulating properties: it can act on enzymes that play a crucial role in gene expression,” explains Dr Anne Gürtler. In relation to the skin, vitamin C is relevant on several levels: “It is a key factor fin boosting the structure, elasticity and regenerative capacity of the skin.”
How useful are dietary supplements?
The body cannot produce vitamin C itself, so it relies on us to supply it. “It is absorbed via receptors in the small intestine,” explains Dr Gürtler. However, these receptors only have a limited absorption capacity and are saturated at some point. This means that above a certain amount, vitamin C is no longer absorbed.
“These transport mechanisms function optimally up to around 200 milligrams per day, after which absorption barely increases. Even if you consume more vitamin C, no more of it enters the body. This shows that excessive intake, for example via high-dose supplements generally has little additional benefit,” says the doctor.
What happens in the event of an overdose?
A genuine overdose of vitamin C is unlikely, says Dr Gürtler: “As it is water-soluble, the body cannot store excess amounts and they are excreted via the kidneys. This is precisely why vitamin C is generally well tolerated.”
However, very high doses (especially in the form of supplements) can lead to side effects. These include gastrointestinal complaints such as diarrhea, flatulence or abdominal cramps. In individuals with prolonged high intake, vitamin C can also promote the formation of kidney stones, especially in people who are already susceptible to them.
