Too much vitamin C - symptoms, risks and sensible upper intake limits

An excessive intake of vitamin C can lead to gastrointestinal complaints and kidney stones. Find out all about the symptoms, limits and sensible dosage of vitamin C supplements here.

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Wissenswertes über "Too much vitamin C"

An excessive intake of vitamin C can lead to gastrointestinal complaints and kidney stones. Find out all about the symptoms, limits and sensible dosage of vitamin C supplements here.

Vitamin C, also known as ascorbic acid, is a vital, water-soluble vitamin that plays a central role in many physiological processes. Among other things, it supports the immune system, promotes iron absorption, has an antioxidant effect and is involved in collagen formation. As the human body cannot produce vitamin C itself, it must be supplied daily through food or food supplements.

In principle, vitamin C is very well tolerated - excess amounts are excreted via the kidneys. Nevertheless, side effects can occur if the intake is very high over the long term, especially with high-dose food supplements. These mostly affect the digestive tract and can vary in severity depending on sensitivity. The risk of certain kidney stones is also discussed among experts, particularly in the case of genetic predisposition or high oxalate consumption.

The European Food Safety Authority (EFSA) has set a tolerable upper limit for vitamin C in order to avoid adverse effects. A balanced diet is usually sufficient to cover the requirement - fruit and vegetables such as peppers, citrus fruits and broccoli provide plenty of it. Additional intake should be individually tailored, especially if there is an increased need or for targeted therapeutic use.

Typical symptoms of an excessive intake of vitamin C:

Nausea
Abdominal pain or cramps
Flatulence
Diarrhoea
Irritation of the gastric mucosa

Long-term risks (with very high and regular intake):

Increased risk of kidney stones (oxalate stones)
Altered iron utilisation (in haemochromatosis)
Stress on kidney function with previous damage

Upper limits according to professional societies:

EFSA (European Food Safety Authority): 2000 mg/day
Institute of Medicine (USA): also 2000 mg/day

When does vitamin C supplementation still make sense?

For acute or chronic infections
For severe oxidative stress
For people with malabsorption
In case of severe physical or mental stress
For smokers (increased requirement)

Recommended natural sources of vitamin C:

Paprika
Rose hip
Sea buckthorn
Broccoli
Citrus fruits
Berries (e.g. blackcurrant)

Literature references:

EFSA Panel on Dietetic Products, Nutrition and Allergies (2013). ""Scientific Opinion on the Tolerable Upper Intake Level of Vitamin C.""
Institute of Medicine (2000). ""Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids.""
German Society for Nutrition (2023). ""Vitamin C - Functions, requirements and sources of supply.""