Ascorbic acid

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Vitamin C

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L-Ascorbic_acid

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Vitamin C

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Vitamin C

Vitamin C, also known as ascorbic acid, is an essential nutrient for humans and various other animal species. It plays a crucial role in many physiological processes, including the synthesis of collagen, the absorption of iron, and the maintenance of a healthy immune system. This article will discuss the functions, dietary sources, recommended daily intake, deficiency, and supplementation of vitamin C.

Functions

Vitamin C is a water-soluble vitamin that has several important functions in the human body:

• Collagen synthesis: Vitamin C is necessary for the synthesis of collagen, a structural protein found in connective tissues, skin, and bones [^1^].
• Antioxidant activity: As an antioxidant, vitamin C helps to neutralize free radicals, thereby reducing oxidative stress and protecting cells from damage [^2^].
• Immune system support: Vitamin C contributes to the proper functioning of the immune system by supporting the production and function of white blood cells [^3^].
• Iron absorption: Vitamin C enhances the absorption of non-heme iron from plant-based sources by reducing it to a more easily absorbed form [^4^].

Dietary Sources

Vitamin C is found in a wide range of fruits and vegetables. Some of the best dietary sources of vitamin C include:

• Citrus fruits (e.g., oranges, grapefruits, lemons, limes)
• Kiwifruit
• Strawberries
• Guavas
• Papayas
• Pineapples
• Melons
• Mangoes
• Tomatoes
• Bell peppers
• Broccoli
• Brussels sprouts
• Leafy greens (e.g., spinach, kale, mustard greens)
• Cauliflower
• Cabbage

It is important to note that vitamin C is sensitive to heat and light, so cooking and storage methods can affect the nutrient content of these foods [^5^].

Recommended Daily Intake

The recommended daily intake (RDI) of vitamin C varies depending on factors such as age, sex, and life stage. According to the National Institutes of Health (NIH), the following RDIs apply for vitamin C [^6^]:

• Infants (0-12 months): 40-50 mg/day
• Children (1-8 years): 15-25 mg/day
• Adolescents (9-18 years): 45-75 mg/day
• Adults (19+ years): 75-90 mg/day (additional 35 mg/day for smokers)
• Pregnant women: 80-85 mg/day
• Breastfeeding women: 115-120 mg/day

Deficiency

Vitamin C deficiency, known as scurvy, is relatively rare in developed countries but can still occur in individuals with inadequate dietary intake or poor absorption. Symptoms of scurvy include:

• Fatigue
• Muscle weakness
• Joint pain
• Swollen, bleeding gums
• Bruising easily
• Anemia
• Slow wound healing

Severe vitamin C deficiency can lead to serious health complications and even death if left untreated. Treatment involves the administration of vitamin C supplements or increasing dietary intake of vitamin C-rich foods [^7^].

Supplementation

Vitamin C supplements are available in various forms, including tablets, capsules, chewable tablets, and effervescent tablets. Some individuals may choose to take vitamin C supplements to help meet their daily requirements, especially if they have difficulty obtaining sufficient amounts from their diet. However, it is essential to note that excessive vitamin C intake can cause side effects, such as diarrhea, nausea, and stomach cramps. The NIH has established a tolerable upper intake level (UL) for vitamin C, which is the maximum daily intake unlikely to cause adverse health effects 1:

• Children (1-8 years): 400-650 mg/day
• Adolescents (9-18 years): 1,200-1,800 mg/day
• Adults (19+ years): 2,000 mg/day
• Pregnant and breastfeeding women (18 years and younger): 1,800 mg/day
• Pregnant and breastfeeding women (19 years and older): 2,000 mg/day
• It is generally recommended to obtain essential nutrients, including vitamin C, from a well-balanced diet rather than relying on supplements. However, if you are considering taking vitamin C supplements, it is best to consult a healthcare professional for personalized advice.

Liver Safety of Ascorbic Acid

There is no evidence to suggest that vitamin C, in physiologic or moderately high doses, causes acute liver injury or jaundice.

Mechanism of Action

Vitamin C, also known as L-ascorbic acid, is a water-soluble vitamin. Its primary function is to act as an electron donor and intracellular antioxidant, protecting critical intracellular molecules and enzyme systems from reactive oxygen species. Additionally, vitamin C serves as a cofactor in various biochemical synthetic reactions, collagen cross-linking, the synthesis of neuropeptides and hormones, and non-heme iron absorption.

Side Effects

Physiological and even excessive intakes of up to 2 grams daily have virtually no side effects. However, higher doses of vitamin C can cause diarrhea, nausea, abdominal discomfort, flushing, dizziness, and headache. These doses may also be associated with transient serum aminotransferase elevations.

See Also

• Vitamins
• Vitamin A
• Vitamin D
• Vitamin E
• Vitamin K

External Links

• NIH Office of Dietary Supplements: Vitamin C
• Harvard T.H. Chan School of Public Health: Vitamin C
• Medical News Today: Vitamin C: Why we need it
• Footnotes: Institute of Medicine (US) Panel on Dietary Antioxidants and Related Compounds. (2000). Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academies Press

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