Vitamin C is an essential nutrient for the human body. Vitamin C (ascorbic acid) is a water-soluble vitamin. It is easily absorbed by the body and just as easily excreted, so vitamin C does not accumulate in the body.
Most plant and animal tissues are capable of synthesizing vitamin C from glucose, but unfortunately the human body is not capable of synthesizing ascorbic acid, so the intake of vitamin C with food is essential.
Vitamin C acts as an essential factor in many of the body's fermentation reactions and is a powerful antioxidant that can help neutralize free radicals.
Functions and health
Vitamin C is a powerful reducing agent and affects many oxidation and reduction reactions. It acts as an electron donor and protects irreplaceable molecules in the body, such as proteins and lipids from free radical damage, for example, from cigarette smoke.
In the intestines, vitamin C protects iron from oxidation thus boosts its absorption, it participates in the synthesis of iron ions (Fe3+) to the more soluble iron ions (Fe2+).
It is considered that vitamin C also improve copper absorption. Copper is an important antioxidant that helps prevent free radical damage to tissues.
Vitamin C intake can also improve the levels of other vitamins in the body, such as vitamin E, and is necessary for tissue growth and regeneration in all parts of the body, as well as collagen, an essential component in wound healing and connective tissue regeneration, L-carnitine and some neurotransmitters biosynthesis.
Studies have shown the ability of vitamin C as an antioxidant to prevent or delay the development of some types of cancer, cardiovascular diseases, as well as to reduce the risk of other diseases related to oxidative stress, including age-related macular degeneration. Due to its biosynthetic and antioxidant functions, vitamin C plays an important role in the functioning of the immune system.
Vitamin C and eye health
The concentration of ascorbic acid in the aqueous humor, the clear, watery fluid between the cornea and the front of the vitreous, can be up to 20 times higher than in blood. Aqueous fluid washes and nourishes the lens and maintains pressure in the eye. A high concentration of ascorbic acid here acts as a filter to prevent UV light from entering the lens, thus protecting the tissue from oxidative damage, especially photo-induced damage.
Cataracts (an age-related clouding of the lens in the eye that affects vision) and age-related macular degeneration (AMD, an eye condition that causes damage to the macula) are the two leading causes of vision loss and impairment in the elderly.
Research shows that vitamin C may play a role in treating AMD and cataracts, slowing its progression.
Recommended daily dose
For children:
1-10 years: 30 mg/day;
11-14 years: 35 mg/day.
For over 14 years and adults: 40 mg/day.
For pregnant women: the dose of vitamin C is slightly increased (+ 50 mg/day).
For smokers: cigarette smoke causes additional oxidative stress and reduces the body's vitamin C levels.
The recommended dose of vitamin C for smokers is significantly higher (+ 35 to 40 mg per day), it is up to 80 mg/d.
For people at risk of age-related macular degeneration, the recommended dose of vitamin C is even higher, reaching 500 mg/day.
Although severe vitamin C deficiency is not common in developed countries, it affects more underdeveloped, poor countries, low fruit and vegetable consumption and low appetite in general can lead to reduced vitamin C intake, and is not uncommon in people aged 65 and over.
Best food sources of vitamin C
Most people associate vitamin C with citrus fruits. This is not a myth, for example, oranges and grapefruits are excellent sources of vitamin C. Strawberries, pineapples are also very good sources of vitamin C. Mostly, any fresh fruit can be a source of vitamin C, and many vegetables such as broccoli, cauliflower or spinach contain significant amounts of vitamin C.
To ensure the necessary daily dose of vitamin C, it is recommended to take about 5 portions of fruits and vegetables per day.
Vitamin C is not stable, it can degrade during storage, heating, exposure to oxygen, so it should be stored with caution.
The amount of vitamin C decreases as soon as the product is harvested. Keeping it whole and cool the rate at which vitamin C is lost can slow. For example, if broccoli is stored for 6 days at room temperature, the loss of vitamin C can be as high as 80%.
Over the course of a year, there is a 50% loss of vitamin C in frozen products, it can be up to 80% in canned products.
When boiled in water, vegetables and fruits lose 2/3 of the amount of vitamin C, so it is better to use the steaming method for cooking.