Why vitamin C is essential for your health

Vitamin C, also known as ascorbic acid, is an essential nutrient for the health and well-being of our bodies. This vitamin is important for many physiological processes, including supporting the immune system, acting as an antioxidant, and aiding in iron metabolism and collagen production. An adequate intake of vitamin C is crucial for maintaining optimal health. This article provides a detailed overview of the functions, deficiency, and potential overdose of vitamin C, and offers tips for ensuring sufficient intake.

Table of Contents

• What is vitamin C?
• Functions and roles of vitamin C in the body
• Where is vitamin C found?
• Vitamin C deficiency and overdose
• How much vitamin C do we need? – Tips for optimal intake
• Summary

What is vitamin C?

During the age of seafaring, symptoms such as tooth loss, immune weakness, and fatigue were common. These issues were one of the leading causes of death on trading ships during long voyages. Fresh fruits such as citrus fruits had a healing effect, although the reason was initially unknown. Later, biochemist Albert Szent-Györgyi discovered the wonder substance in citrus fruits—vitamin C.
Vitamin C, also called ascorbic acid, is a water-soluble vitamin and one of the most well-known vitamins. Unlike some animal species that can synthesize vitamin C on their own, humans must obtain it daily through their diet (National Institutes of Health, 2024). 

Functions and roles of vitamin C in the body

The functions of vitamin C are diverse and essential for the human body. As a powerful antioxidant, it neutralizes free radicals that can cause cellular damage and are linked to diseases such as cancer and heart disease. Vitamin C also strengthens the immune system by stimulating the production of immune cells and antibodies that fight infections. It plays a central role in collagen formation, which is important for the structure and elasticity of skin, bones, and blood vessels. In addition, vitamin C improves the absorption of iron from plant-based sources, which is especially important for vegetarian and vegan diets.

1) Vitamin C as an antioxidant

One important function of vitamin C is its role as an antioxidant. External influences such as smoking or UV radiation can lead to the formation of free radicals in biological molecules like skin cells, DNA, proteins, or lipids within the human body. These highly reactive molecules attack other cellular structures, generate additional free radicals, and are ultimately responsible for the development of chronic diseases such as cancer, heart disease, and premature aging. Antioxidants like vitamin C neutralize free radicals, helping to protect cells and tissues from damage and thus support overall health (Mayo Clinic, 2023).

2) Vitamin C and the immune system

Adequate intake of vitamin C is essential for a strong and healthy immune system. Vitamin C supports immune cells such as lymphocytes and phagocytes, which are responsible for fighting infections and diseases. It also promotes the formation of antibodies by stimulating the proliferation of B and T cells, which specifically target pathogens and enhance immune defense. A vitamin C deficiency can impair immune function and increase susceptibility to infections. Therefore, ensuring sufficient intake through food—or supplements if necessary—is especially important during the colder months or periods of increased immune stress (Carr, A. C., & Maggini, S., 2017).

3) Vitamin C and collagen production

Vitamin C plays a key role in the production of collagen. Collagen is a protein that provides structure and strength to tissues such as skin, bones, teeth, tendons, and blood vessels. Vitamin C acts as a cofactor for enzymes essential in collagen synthesis, thereby supporting the formation and cross-linking of collagen fibers (DePhillipo, N. N. et al., 2018). This is especially important as we age, when collagen strands become more brittle and collagen synthesis declines. Vitamin C is thus crucial for maintaining the integrity and elasticity of tissues, helping to keep the skin radiant, smooth, and healthy, and to delay signs of aging (Baroni, E.doR. et al., 2012; Varani, J. et al., 2006).

4) Vitamin C and iron metabolism

Another important role of vitamin C is its beneficial interaction with iron metabolism. Vitamin C enhances the absorption of iron from plant-based sources such as spinach by converting it into a more absorbable form (from ferric iron to ferrous iron) (Doseděl, M. et al., 2021). This is particularly relevant for individuals following vegetarian or vegan diets, as iron from plant sources (ferric iron) is not as easily absorbed as iron from animal products (ferrous iron) (Piskin, E. et al., 2022).

Where is vitamin C found?

The human body cannot produce vitamin C on its own (Mayo Clinic, 2023). This makes it all the more important to obtain it daily through the diet. But which foods are rich in vitamin C? Vitamin C-rich foods (per 100 g):

• Chili – 143.7 mg

• Kiwi – 93 mg

• Broccoli – 89.2 mg

• Orange – 53.2 mg

• Lemon – 53 mg

• Papaya – 60.9 mg

• Lychee – 71.5 mg

• Bell pepper – 80.4 mg

• Strawberry – 58.8 mg

Source: Cleveland Clinic, 2023

Vitamin C is a very sensitive micronutrient. Even in foods that are particularly rich in vitamin C, storage and preparation play a crucial role in determining the final vitamin C content. The amount of vitamin C in food can vary depending on the time of harvest, storage conditions, transportation, and preparation methods. Foods should therefore be washed thoroughly but briefly, or steamed gently, to minimize vitamin loss due to the water-soluble nature of vitamin C (Deutsche Gesellschaft für Ernährung e.V., 2015).

Vitamin C deficiency and overdose

Vitamin C deficiency is rare in most developed countries, as most people have access to a varied and balanced diet. Symptoms of vitamin C deficiency include:

• Fatigue, weakness

• Malaise

• Depression

• Gum inflammation, loosening or loss of teeth

• Joint pain

• Poor wound healing

• Petechiae (small red spots on the skin), ecchymoses (bruises), purpura (purple skin spots)

• Can be fatal if left untreated

Source: National Institutes of Health, 2021

A daily intake of up to about 1 g of vitamin C in addition to food is generally not associated with harmful side effects. However, higher doses of 3 to 4 g may lead to nausea or diarrhea (Johnson, L., 2022). Certain individuals—such as those prone to urinary or kidney stones, people with impaired iron metabolism, and patients with kidney disease—have an increased risk of adverse effects from high vitamin C intake (Deutsche Gesellschaft für Ernährung e. V., 2015).

How much vitamin C do we need? – Tips for optimal intake

The recommended daily intake of vitamin C varies depending on age, gender, health status, and other individual factors. Since the human body cannot produce vitamin C on its own, adequate daily intake is essential.

Recommended daily intake of vitamin C

Source: AOK, 2023

Summary

Overall, vitamin C is an essential nutrient that performs numerous important functions in the body. A balanced diet rich in vitamin C-containing foods can help meet daily needs and prevent potential deficiency symptoms. If you have questions about your vitamin C requirements or would like more information, please consult your doctor or a qualified nutrition professional.