Vitamin C foods exist abundantly in nature as various coloured fruits and vegetables. It is a water-soluble vitamin and commonly known as Ascorbic Acid. Vitamin C is a powerful antioxidant and it supports vital body functions and organs.
It usually exists in reduced and oxidized forms as Ascorbate and Dehydroascorbic acid respectively. These two forms are easily inter-convertible and biologically active.
Vitamin C cannot be generated by humans. Hence we depend on the plant-based or animal-based Vitamin C foods to provide us with the required intake.
Handling Vitamin C Foods
Vitamin C is easily destroyed by oxygen, alkali, and high temperature. Hence, one needs to carefully handle Vitamin C foods to avoid damage to Vitamin C by:
- Not over-heating the foods
- Not over-cooking
- Avoiding prolonged exposure to air of juiced, mashed, and cut vitamin C foods. In short, eat them fresh!
Vitamin C Absorption and Critical Factors
When taken through diet or supplements, Vitamin C concentration in blood is balanced through:
- Absorption from small intestine and
- Reabsorption or excretion through kidneys
At low doses (20 mg), absorption can reach nearly 100%, whereas at higher doses (12 g), only 16% is absorbed. Hence, excessive consumption of Vitamin C foods or high doses of the supplements in one go becomes ineffective.
When excreted, a part of Vitamin C is excreted in form of oxalic acid. So, it is advisable for patients with oxalate stones to limit daily intake of Vitamin C to 500 mg.
Vitamin C Functions in our body
Our body requires Vitamin C for normal physiological and psychological functions.
- It helps in the synthesis and metabolism of required nutrients as tyrosine, folic acid, and tryptophan, hydroxylation of glycine, proline, lysine, carnitine
and catecholamine. - It also increases the absorption of iron in the gut by reducing ferric to ferrous state.
- As an antioxidant, it protects the body from free radicals, pollutants, and toxins.
Vitamin C Health Benefits
Collagen synthesis for Flawless Skin
Collagen constitutes the principal protein of skin, bones, teeth, cartilage, tendons, blood vessels, heart valves, inter vertebral discs, cornea, eye lens.
Vitamin C is important in the synthesis and maintenance of collagen especially type III and IV. Also, studies show that Ascorbic Acid is beneficial in wound healing either pre-operative or post-operative.
Supports Energy Metabolism in Muscles
Vitamin C is an important cofactor in
Boosts Immune System
- Vitamin C along with Vitamins: E, B6, B12, Folate and minerals as: Selenium, Zinc, Copper and Iron can stimulate our immune system for body defense.
- Vitamin C is found to prevent over stimulation of the immune system, which can cause tissue damage and inflammation.
- It has an anti-bacterial action.
Prevents Common Cold and Rhinitis
High doses of Vitamin C (1-3g) can reduce duration and symptoms of common cold. Studies suggest that administration of Ascorbic Acid in rhinitis stimulates our immune system to synthesize immunoglobulins to attack infections.
Prevents Neurodegenerative disorders
Ascorbic Acid has shown to be effective in reducing cognitive functions decline which occurs in Alzheimer disease.
Also, some studies show that administration of Ascorbic Acid with anti-pscychotic drugs is beneficial in reducing free radicles which cause brain damage leading to schizophrenia.
Supports Heart Health
- Studies show that Ascorbic Acid facilitates the conversion of cholesterol into bile acids and hence lowers blood cholesterol levels.
- Ascorbic acid prevents LDL oxidation through its antioxidant effect.
- It decreases LDL, cholesterol and triglycereids, and enhances HDL levels. Thus it reduces risk of atherosclerosis and stroke.
- It strengthens arteries by stimulating collagen synthesis in artery walls and prevent adhesion of white blood cells to damaged arteries.
- It also helps to preserve Vitamin E – alpha-tocopherol inside the cells.
Prevents Diabetic Complications
Studies have found that Hyperglycemia in both
The increase in ROS is responsible for nephropathy and retinopathy. Administration of both Vitamins C and E show to decrease ROS levels.
Prevents Heavy Metals Toxicity
Studies show that Vitamin C is effective in
Lowers Cancer Risk
Regular intake of Vitamin C can lower the risk for cancer of oesophagus, oral cavity, stomach, pancreas, cervix, rectum and breast and also non-hormonal cancers. The suggested mechanisms for Vitamin C in the treatment and prevention of cancer are:
- Enhancing the immune system
- Stimulating the formation of collagen
- Preventing metastasis (spreading)
- Preventing viruses that can cause cancer
- Wound healing in cancer patients after surgery
- Enhancing the effectiveness of chemotherapy
- Reducing the toxicity of chemotherapy
- Preventing free radical damages
- Neutralizing some carcinogens
Also, in-vitro studies show high intravenous doses of Vitamin C have preferable targeting effect to tumor cells rather than normal cells.
Vitamin C Recommended Dietary Allowance (RDA)
| Age Group | RDA mg/day | Upper Limit |
| 0-6 months | 40 | |
| 7-12 months | 50 | |
| 1-3 years | 15 | 400 |
| 4-8 years | 25 | 650 |
| 9-13 years | 45 | 1200 |
| 14-18 years (Male) | 75 | 1800 |
| 14-18 years (Female) | 65 | 1800 |
| more than 18 years (Male) | 90 | 2000 |
| more than 18 years (Female) | 75 | 2000 |
| Pregnancy | 80 – 90 | |
| Breastfeeding | 115 – 125 |
Vitamin C Foods
Plant sources are important because of high content of vitamin C up to 5,000 mg/100 g. Vitamin C is found in citrus fruits, green peppers, red peppers, strawberries, tomatoes, broccoli, brussels sprouts, turnip, Indian gooseberry and other leafy vegetables. Top sources of Vitamin C include:
- Citrus fruits – Orange, Lime, Grapefruit, Mandarins, and Pomelo
- Berries – Raspberry, Blackberry, Cranberry
- Guava
- Herbs such as curry leaves and Moringa
- Indian Gooseberry or Amla is the richest plant-based sources of Vitamin C.
- Kiwi
Dietary Tip: one piece of Amla, or a Kiwi, or an Orange is enough to cover your daily Vitamin C.
Vitamin C Deficiency
Causes of Vitamin C Deficiency
- Low fruits and vegetables intake
- Poor diet choices or imposed restrictive diet plans
- Certain drugs like nifedipine and aspirin lead to Vitamin C deficiency
High risk groups for Vitamin C Deficiency
- Cigarette smokers exhibit decreased plasma Vitamin C concentrations despite adequate dietary intakes
- Individuals with chronic high blood sugar levels due to diabetes, sepsis, or stress.
- Adult males consistently exhibit lower plasma vitamin C concentrations across the life cycle than their female counterparts.
Symptoms of Vitamin C Deficiency
Scurvy occurs upon Vitamin C deficiency. Common physical symptoms of scurvy include:
- swelling of the lower extremities
- bleeding gums
- malaise or fatigue
- bruising
- petechiae
- corkscrew hairs
- dry skin
- hemorrhaging
- depression
hysteria social introversion.
On intervention of Vitamin C from foods and supplements, these psychological disorders relief firstly.
Toxicity due to high intake of Vitamin C
Single doses >1000 mg/day can cause gastrointestinal distress, nausea, and osmotic diarrhea, as the body attempts to rid itself of the high concentration of vitamin C.
The tolerable upper intake level (UL) for vitamin C is 2000 mg daily.
The side effects are generally not serious and can be easily reversed by reducing the intake of Vitamin C. Furthermore, there is no consistent and compelling data on serious health effects of vitamin C in humans.
References
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3783921/
https://journals.sagepub.com/doi/pdf/10.1177/1533210110392951
