Vitamin C is also known as ascorbic acid. This water-soluble vitamin is essential for various bodily functions, including supporting the immune system and aiding collagen production. As the human body cannot produce vitamin C on its own, obtaining an adequate amount through diet is crucial. In industrialised countries, this is generally not an issue. However, in certain situations, taking a vitamin C supplement may be beneficial.
Vitamin C at a glance
Vitamin C, or ascorbic acid, is an essential nutrient that the human body cannot synthesise.
It plays a key role in immune function, collagen formation, and protecting cells from free radicals.
Adult women typically require 95 mg per day, while men need 110 mg.
Healthy individuals can meet their needs by regularly consuming fruit and vegetables.
In some cases, taking a vitamin C supplement may help prevent deficiencies.
What is Vitamin C?
Vitamin C is a water-soluble vitamin, also called ascorbic acid. The body neither produces nor stores this essential nutrient, making regular dietary intake necessary. Vitamin C is naturally present in many foods and can also be synthetically produced. Due to its antioxidant properties, it is often used as an additive to extend the shelf life of processed foods such as meats and sausages.
What are the benefits of vitamin C?
Vitamin C serves multiple functions in the body. It supports the immune system and protects cells from oxidative stress.
Additionally, vitamin C contributes to:
normal collagen formation,
normal psychological function,
a properly functioning nervous system, and
iron absorption.
Does vitamin C help with colds?
Many people believe that vitamin C can prevent and treat colds. However, the evidence on this is inconclusive. Studies do not consistently show a clear effect on reducing the risk, severity, or duration of cold symptoms.
Regular supplementation may provide some benefits for endurance athletes, such as marathon runners, but appears to have little to no effect for most other people.1
Does vitamin C help fight cancer?
Experiments on cell cultures and mice suggest that high-dose vitamin C might help combat cancer. However, this theory has yet to be definitively proven in human studies. For instance, a 2022 study found that high-dose vitamin C had no impact on survival rates or tumour growth in bowel cancer patients.2
How much vitamin C per day?
Vitamin C requirements depend on factors such as gender, age, and lifestyle. The German Nutrition Society (DGE) recommends the following daily intake levels:
95 mg for women aged 19 and over
110 mg for men aged 19 and over
90 mg for female teenagers aged 15 and over
105 mg for male teenagers aged 15 and over
20 to 85 mg for infants and children up to 15 years old.3
When is the daily requirement higher?
Tagesbedarf kann aus verschiedenen Gründen erhöht sein.
Pregnant women require 105 mg per day from the fourth month onwards, increasing to 125 mg per day during breastfeeding.
Smokers need significantly more vitamin C, with recommendations of 135 mg per day for women and 155 mg per day for men.4
How to meet daily vitamin C needs?
A well-balanced diet usually provides sufficient vitamin C. As this vitamin is found in many fruits and vegetables, vegans and vegetarians can easily meet their daily requirements. However, animal-based foods contain little to no vitamin C.
Which foods are highest in vitamin C?
Citrus fruits are widely recognised for their vitamin C content, but many other foods contain significantly higher amounts.
Here are some of the richest sources of vitamin C (content in mg per 100 g):
| Food | Vitamin C content (mg per 100 g) |
|---|---|
| Acerola | 1,677 mg |
| Rose hips | 1,250 mg |
| Nettle | 333 mg |
| Lemon balm | 253 mg |
| Guava | 273 mg |
| Sea buckthorn | 450 mg |
| Blackcurrants | 189 mg |
| Parsley | 160 mg |
| Wild garlic | 150 mg |
| Red pepper | 139.5 mg |
| Broccoli | 115 mg |
How should vitamin C-rich foods be stored and prepared?
Prolonged storage and cooking can lead to significant vitamin C loss in plant-based foods. To retain as much vitamin C as possible, they should be consumed soon after purchase and cooked for a minimal amount of time.
What causes vitamin C deficiency?
A prolonged lack of fruit and vegetables in the diet can eventually lead to vitamin C deficiency. However, due to the abundance of food in industrialised countries, this is now rare. The National Consumption Study II, conducted in Germany between 2005 and 2006, found that all age groups met or exceeded their recommended vitamin C intake.5
Nonetheless, certain factors can increase the risk of deficiency, including:
Pregnancy
Smoking
Chronic gastrointestinal diseases
Inflammatory conditions
Cancer
Surgery
Alcohol abuse
Intense physical labour
Endurance sports
What are the symptoms of vitamin C deficiency?
A lack of ascorbic acid can lead to various non-specific symptoms, such as slow wound healing and increased susceptibility to infections.
Other potential symptoms include:
Joint pain
Muscle pain
Weight loss
Fatigue
Irritability
Weakness
Welche Folgen hat ein dauerhafter Mangel?
Ein schwerer Mangel kann auf Dauer ernste Folgen für die Gesundheit haben. Betroffene erkranken an Skorbut. Dadurch kommt es bei ihnen unter anderem zu Veränderungen des Bindegewebes, der Knochen und Gelenke sowie zu Infektionen, Blutungen und Zahnausfall. Ohne Gegenmaßnahmen endet Skorbut sogar tödlich.
Die bei Kleinkindern durch den anhaltenden Mangel ausgelöste Erkrankung ist die Moeller-Barlow-Krankheit. Sie äußert sich mit ähnlichen Symptomen wie Skorbut. Zudem führt die Moeller-Barlow-Krankheit zu schweren Störungen der Knochenbildung und des Wachstums.
Wie behandelt man einen Vitamin-C-Mangel?
Bei möglichen Mangelerscheinungen kann die Bestimmung des Vitamin-C-Status im Blut sinnvoll sein. Die Normalwerte liegen bei 5 bis 15 Milligramm Ascorbinsäure pro Liter. Bestätigt sich der Verdacht, helfen frisches Gemüse und Obst sowie Vitamin-C-Präparate beim Beseitigen des Mangels.
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Is too much vitamin C dangerous?
Vitamin C has a very short half-life, and the body cannot store it. This means that any excess is simply excreted in the urine. It is almost impossible to overdose on vitamin C through diet alone. However, consuming very high doses in supplement form may occasionally cause mild side effects.
What is the safe upper limit for vitamin C intake?
According to the German Nutrition Society (DGE), a daily intake of up to 1 gram of vitamin C is considered safe. Temporary side effects, such as diarrhoea, usually occur only at doses of 3 to 4 grams per day.6
The European Food Safety Authority (EFSA) has not set an official maximum daily intake for vitamin C due to its low toxicity and inconsistent data.7
The German Federal Institute for Risk Assessment (BfR) recommends the following upper limits:
- 250 mg per day for vitamin C supplements
- 60 mg per 100 g in fortified foods
- 16 mg per 100 ml in beverages.8
Who is at risk of side effects from excessive vitamin C?
Although vitamin C is generally safe, certain individuals should avoid excessive intake:
- People prone to kidney stones: The German Association of Internists advises against taking 1 gram or more of vitamin C per day on a long-term basis.9
- People with haemochromatosis (a condition causing excessive iron absorption) should limit their intake to a maximum of 500 mg per day, as vitamin C enhances iron absorption.10
Should you take vitamin C every day?
Since the body does not store vitamin C, it is best to consume vitamin C-rich foods daily. If your lifestyle or a medical condition increases your vitamin C needs, taking a daily supplement may be beneficial.
Important to know
If you are not a medical specialist and have complaints, specific health conditions, or suspect deficiencies, please make sure to consult a doctor to discuss this.
- 1 Hemilä H, Chalker E: Vitamin C zur Vorbeugung und Behandlung von Erkältungen (Veröffentlichung: 31.01.2013). URL: https://www.cochrane.org/de/CD000980/ARI_vitamin-c-zur-vorbeugung-und-behandlung-von-erkaltungen (zuletzt aufgerufen am: 19.09.2024).
- 2 Feng Wang et al.: A Randomized, Open-Label, Multicenter, Phase 3 Study of High-Dose Vitamin C Plus FOLFOX ± Bevacizumab versus FOLFOX ± Bevacizumab in Unresectable Untreated Metastatic Colorectal Cancer (VITALITY Study) (Veröffentlichung: 03.10.2022). URL: https://pubmed.ncbi.nlm.nih.gov/35929990/ (zuletzt aufgerufen am: 19.09.2024).
- 3 Deutsche Gesellschaft für Ernährung e.V.: Empfohlene Vitamin-C-Zufuhr (Stand: 2015). URL: https://www.dge.de/wissenschaft/referenzwerte/vitamin-c/ (zuletzt aufgerufen am: 19.09.2024).
- 4 Deutsche Gesellschaft für Ernährung e.V.: Empfohlene Vitamin-C-Zufuhr (Stand: 2015). URL: https://www.dge.de/wissenschaft/referenzwerte/vitamin-c/ (zuletzt aufgerufen am: 19.09.2024).
- 5 Max Rubner-Institut: Ergebnisbericht, Teil 2 Nationale Verzehrsstudie II (Veröffentlichung: 2008). URL: https://www.mri.bund.de/fileadmin/MRI/Institute/EV/NVSII_Abschlussbericht_Teil_2.pdf (zuletzt aufgerufen am: 04.10.2024).
- 6 Deutsche Gesellschaft für Ernährung e.V.: Ausgewählte Fragen und Antworten zu Vitamin C (Stand: 2015). URL: https://www.dge.de/gesunde-ernaehrung/faq/vitamin-c/ (zuletzt aufgerufen am: 19.09.2024).
- 7 European Food Safety Authority: Overview on Tolerable Upper Intake Levels as derived by the Scientific Committee on Food (SCF) and the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) (Stand: Juni 2024). URL: https://www.efsa.europa.eu/sites/default/files/2024-05/ul-summary-report.pdf (zuletzt aufgerufen am: 19.09.2024).
- 8 Bundesinstitut für Risikobewertung: Höchstmengenvorschläge für Vitamin C in Lebensmitteln inklusive Nahrungsergänzungsmitteln (Veröffentlichung: 2021). URL: https://www.bfr.bund.de/cm/343/hoechstmengenvorschlaege-fuer-vitamin-c-in-lebensmitteln-inklusive-nahrungsergaenzungsmitteln.pdf (zuletzt aufgerufen am: 19.09.2024).
- 9 Internisten im Netz: Vitamin-C-Pillen können Risiko für Nierensteine erhöhen (Veröffentlichung: 10.03.2013). URL: https://www.internisten-im-netz.de/aktuelle-meldungen/aktuell/vitamin-c-pillen-koennen-risiko-fuer-nierensteine-erhoehen.html (zuletzt aufgerufen am 19.09.2024).
- 10 Uniklinikum Würzburg: Hämochromatose. URL: https://www.ukw.de/medizinische-klinik-ii/hepatologie/schwerpunkte/chronische-lebererkrankungen/haemochromatose/ (zuletzt aufgerufen am: 19.09.2024).
