Nov 27, 2023
Vitamin C / Ascorbic Acid - Functions | Deficiency | Best Sources
Vitamin C, also known as ascorbic acid, is a water-soluble nutrient that functions as a cofactor for several metabolic functions. Vitamin C is required for the biosynthesis of collagen, Carnitine, neurotransmitters, and for iron absorption.
SYMPTOMS OF VITAMIN C DEFICIENCY
Vitamin C deficiency is associated with impaired immunity, anemia, bleeding gums, scurvy, poor wound healing, capillary haemorrhage, atherosclerotic plaques, and fatigue (probably associated with carnitine biosynthesis.
WHO IS AT A RISK OF VITAMIN C DEFICIENCY?
The elderly, those practicing a fad diet, those with presumed food allergies, or following restrictive diets, those who smoke, those who practice alcoholism, those who have renal failure due to filtration of water-soluble vitamin C during dialysis, those who do not consume fruits and vegetables daily, individuals with disorders of the GI tract like inflammatory bowel disease have high vitamin C requirements.
Conditions like asthma, collagen disorders, arthritis, infections like sinusitis, heat stroke, and burns are causes of increased need for vitamin C.
WHAT IS THE RECOMMENDED DAILY INTAKE OF VITAMIN C?
The recommended daily allowance of vitamin C is 75mg for women and 90mg for men, respectively. Although the upper limit for vitamin C is not established, since our body does not absorb 100% of the vitamin C we consume, 1000mg per day is a prudent limit.
WHY SHOULD ONE SUPPLEMENT WITH VITAMIN C?
When foods are cooked in large amounts of water and exposed to extensive heating or exposed to air, it can lead to a loss of vitamin C. Vitamin C is heat sensitive and cooking or boiling removes the nutritional value.
While a small amount of vitamin C is stored within adrenal glands, leukocytes, and the pituitary, there is very little storage of vitamin C in the body. Plasma concentration of vitamin C is largely related to recent intake.
Humans cannot synthesize vitamin C as we lack the enzyme L-gulonolactone oxidase.
Vitamin C deficiency and its manifestations are a consequence of inadequate dietary intake.
The above factors make vitamin C an essential vitamin that needs to be acquired through diet or supplements.
VITAMIN C BOOSTS IMMUNE FUNCTION
- Vitamin C contributes to immune defense by supporting various functions of the innate and adaptive immune system.
- Vitamin C supports the epithelial barrier function against pathogens and promotes the oxidant scavenging activity of the skin.
- Vitamin C accumulates in phagocytic cells, such as neutrophils, and can enhance chemotaxis and microbial killing activity.
- As an effective antioxidant, vitamin C contributes to protecting neutrophils and lymphocytes from oxidative stress.
- Vitamin C reduces the production of pro-inflammatory cytokines and supports the production of interferons (which facilitate the ability of cells to initiate protective cellular defenses).
- Vitamin C triggers a cell-mediated immune response which refers to the activation of macrophages, natural killer cells, and antigen-specific T-lymphocytes.
- Vitamin C is needed for the clearance of spent neutrophils from the sites of infection by macrophages.
ROLE OF VITAMIN C IN COLLAGEN FORMATION
- The healing of musculoskeletal tissues, such as bones, and tendons is dependent on the capacity of collagen synthesis. As per studies, vitamin C may enhance collagen synthesis and tissue healing.
- Vitamin C is an essential cofactor for the prolyl hydroxylase (to stabilize the collagen molecule) and lysyl hydroxylase (to give structural strength) which are the essential enzymes required for collagen synthesis.
- As we age, the ability of the body to synthesize collagen decreases which leads to joint degradation, the appearance of fine lines, sagging of skin, muscle aches, and poor hair growth.
- Chronic UV exposure makes your skin susceptible to significant loss of collagen fibrils.
- Adequate intake of vitamin C is the first line of defense in preventing collagen loss, impacts the body’s ability to make collagen, promotes faster wound healing, and better joint health.
VITAMIN C SUPPORTS ABSORPTION OF IRON
- Iron in foods naturally occurs in two forms, heme iron and non-heme iron which are absorbed and handled differently by our bodies.
- Heme iron which is derived from haemoglobin and myoglobin is well absorbed and relatively little affected by other foods eaten in the same meal. This is not the case with non-heme iron, the absorption of which is greatly influenced by meal composition.
- The higher bioavailability of dietary iron can be achieved by increasing the content of vitamin C in food that enhance iron absorption.
- Vitamin C both enhances iron absorption, and also decreases the content of inhibitors (phytates, tannins).
- Vitamin C prevents the formation of insoluble and unabsorbable iron by reducing ferric iron to the more soluble and absorbable ferrous form.
VITAMIN C IMPROVES HEART HEALTH
- Vitamin C contributes to improved nitric oxide production of the endothelium, which in turn, enhances vasodilation and reduces blood pressure.
- Vitamin C inhibits LDL, which can lead to the prevention of atherosclerosis and its complications.
- Studies suggest that vitamin C deficiency is associated with a higher risk of mortality from cardiovascular disease.
- Vitamin C has been shown to reduce monocyte adhesion to the endothelium which is considered to be one of the early signs of the development of atherosclerosis.
- The higher plasma vitamin C concentration is linked to a higher antioxidant effect which may be related to reducing heart disease risk.
BEST SOURCES OF VITAMIN C
Orange, lemons, broccoli, grapes, cantaloupe, tomato, potato, cabbage, spinach, strawberry, papaya, kiwi, guava, lychee, rosehips, cauliflower, peas, and kale are some of the best sources of vitamin C.