Ascorbic acid
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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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
There is no evidence to suggest that vitamin C, in physiologic or moderately high doses, causes acute liver injury or jaundice.
Mechanism of Action[edit | edit source]
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[edit | edit source]
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[edit | edit source]
External Links[edit | edit source]
- 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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