What is Vitamin C or Ascorbic Acid?
There vitamin C or L-ascorbic acid - also called antiscorbutic factor - is a rather delicate water-soluble vitamin and susceptible to environmental conditions; it is particularly perishable when exposed to intense heat and oxidation (exposure to oxygen).
L-ascorbic acid has various biological functions - antioxidant, collagen synthesis, immune functioning, wound healing and iron absorption optimizer - and is abundantly present especially in fresh and raw fruit and vegetables.
Also very useful in the food industry and for the numerous health virtues attributed to it, the production and trade of vitamin C as an additive and cosmetic ingredient - in various chemical forms, such as calcium or sodium ascorbate - and as a food supplement, is among the most important in the world.
Where is vitamin C (L-ascorbic acid) found?
Vitamin C is abundantly present in certain foods of plant origin, while foods of animal nature generally not they contain it in significant quantities.
The only exceptions are:
- Human breast milk, in an amount of 5.0 mg / 100 g - while cow's milk contains some only 1.0 mg / 100 g
- Milk formulated for babies, in the measure of 6.1 mg / 100
- Raw liver (any) - however unadvisable from a food safety point of view. For example, raw chicken liver contains 17.9 mg / 100 g of L-ascorbic acid but, following full cooking (e.g. sliced and stir-fried), this content is reduced at 2.7 mg / 100 g.
Chicken eggs do not naturally contain vitamin C, not even raw.
Foods of plant origin are globally considered a good source of L-ascorbic acid, although the specific quantity depends on the product in question, the nature of the soil and the growing climate, the state of ripeness at the time of harvest, the time the conditions of conservation, and any preparatory work for consumption.
The most common and widespread products in the Italian diet that contain high concentrations of vitamin C are:
- Chili Peppers
- Black cabbage
- Turnip greens
- Rocket salad
- Brussels sprouts
- Swiss chard
- Mandarin oranges
- Green radicchio
Vitamin C is also quite abundant in the germ of seeds, such as that of rice, corn, wheat, etc .; on the other hand, due to storage and industrial processing, often a large part of the L-ascorbic acid remains compromised. It is different if we take the sprouts into analysis. Being “living” organisms, these keep the levels of vitamin C unchanged and can be considered excellent alternative nutritional sources.
There is also a long list of foreign products very rich in L-ascorbic acid, however scarcely in use within the Bel Paese. Between these:
- Camu camu
- Indian gooseberry
- Rose fruit
- Passion fruit
Note: researching the specific nutritional content in vitamin C of foods, pay attention to the state or form of the same. If dried or preserved, and rich in L-ascorbic acid, they are most likely foods artificially enriched in antioxidants.
Warning! Cooking up to or above 60 ° C causes the loss of at least 60 % of the total vitamin C, an amount that increases over time. High decreases of L-ascorbic acid are observed by leaching, or by dispersion-dilution in water. This happens, for example, by soaking fruit and vegetables cut into pieces, or boiling them by poaching. Cutting and storing at low temperatures, on the other hand, does not seem to cause large losses of vitamin C, as long as the food surfaces are not left exposed to the air - it is necessary to adequately cover with film or lids.
Foods fortified in Vitamin C, additives and food supplements
Several food safety agencies have evaluated the effect of food fortification with ascorbates and determined whether it is relevant.
In Canada, for example, fortification has been made "mandatory" for several food classes, such as fruit-flavored drinks, blends and concentrates, low-energy diet foods, meal replacement products and evaporated milk.
The content of tablets and capsules ranges from 25mg to 1500mg per serving.
The most commonly used chemical forms of supplement are ascorbic acid, sodium ascorbate and calcium ascorbate. Vitamin C molecules can also be bound to the fatty acid palmitate, creating ascorbyl palmitate (see below), or incorporated into liposomes.
Ascorbic acid and some of its salts and esters are additives commonly added to various types of foods, mainly with the intent of delaying oxidation.
The European abbreviations relating to additives containing vitamin C are:
- Ascorbic acid E300
- Sodium ascorbate E301
- Calcium ascorbate E302
- E304 fatty acid esters of ascorbic acid such as ascorbyl palmitate.
How much vitamin C (L-ascorbic acid) to take with the diet?
The recommended vitamin C intake levels for the adult population (> 18 years) are slightly different depending on the bibliographic source consulted:
- Recommended Nutrient Intake Levels for the Italian population: 105 mg / day males and 85 mg / day females
- European Food Safety Authority (EFSA): 110 mg / day males and 95 mg / day females
- World Health Organization (WHO): 45 milligrams (mg) per day (day) or 300 mg per week
- European Commission Council on nutrition labeling: 80 mg / day
- Health Canada 2007: 90 mg / day males and 75 mg / day females
- United States National Academy of Sciences: 90 mg / day males and 75 mg / day females
- Japan National Institute of Health and Nutrition: 100 mg / day
- India National Institute of Nutrition, Hyderabad: 40 mg / day.
Each research institute then estimated the recommended intake levels for different population groups, such as growing-up, pregnant, nursing and smokers. The following is recommended by the LARN:
- 1-3 years: 35 mg / day
- 4-6 years: 45 mg / day
- 7-10 years: 60 mg / day
- 11-14 years 90 mg / day males and 80 mg / day females
- 15-17 years 105 mg / day males and 85 mg / day females
- Pregnant: 130 mg / day
- Nutrients: 130 mg / day
- Smokers: + 35 mg / day *.
* Since cigarette smokers and people exposed to related secondhand smoke show lower plasma levels of L-ascorbic acid than non-smokers, an increase of 35 mg / day has been established. The hypothetical mechanism underlying this circumstance would be the oxidative damage caused by the inhalation of smoke. To the benefit of this theory, the outcome of a meta-analysis that showed an inverse relationship between vitamin C intake and lung cancer, although it concluded that more research is needed to confirm this observation.
The maximum tolerable dose - Tolerable Upper Intake Level - of L-ascorbic acid for an adult is about 2,000 mg / day, as certain human studies have reported the occurrence of diarrhea and other gastrointestinal disorders at doses above 3,000 mg. / day.
A 2013-2014 survey conducted by the National Center for Health Statistics reported that for adults 20 years of age and older, men consumed an average of 83.3 mg / day and women 75.1 mg / day of vitamin C. This means that half of women and more than half of men do not introduce the minimum quantity of ascorbic acid necessary for psychophysical well-being. The same survey stated that approximately 30 % of adults report having consumed a vitamin C dietary supplement or a multi-vitamin / mineral supplement that included vitamin C and that, for these subjects, the total consumption was between 300 and 400. mg / day.
What is Vitamin C used for?
Vitamin C is an essential nutrient; since the human organism is unable to synthesize it, we are obliged to introduce it with food. Other animals, such as large herbivores, on the other hand, have the ability to produce it autonomously. Goats, for example, synthesize L-ascorbic acid in large quantities; a healthy adult animal is capable of producing over 10,000 mg of L-ascorbic acid per day - increasing it in case of stress.
The functions of vitamin C in the human body are different. It is a cofactor of many enzymatic reactions that mediate a variety of essential biological functions, including collagen synthesis and wound healing.
Another primary biochemical role of vitamin C is that of a powerful antioxidant (reducing agent) by donating electrons in various enzymatic and non-enzymatic reactions. In this way L-ascorbic acid converts into an oxidized state, such as semidehydroascorbic acid or dehydroascorbic acid. These compounds can be restored to a reduced state by glutathione and NADPH-dependent enzymatic mechanisms.
L-ascorbic acid is also very useful in optimizing intestinal iron absorption, hindering iron deficiency anemia in predisposed subjects.
Vitamin C is recommended in periods of greatest immune vulnerability, given its trophic role in relation to the immune system.
What does vitamin C (L-ascorbic acid) deficiency entail?
The human body can only store a certain amount of vitamin C inside the liver; in case of chronic shortage, these stocks run out quite quickly.
Vitamin C deficiency leads to impaired collagen synthesis, which is too unstable, contributing to the more severe symptoms of scurvy. Furthermore, the lack of L-ascorbic acid causes the malfunction of many other enzymes that depend on it.
Scurvy manifests itself with spots and bleeding under the skin (especially on the thighs and legs), spongy gums, impaired hair growth, and poor wound healing. People with scurvy appear pale, depressed, and move with difficulty. In advanced scurvy, more extensive wounds open, suppuration, tooth loss, bone abnormalities appear, and eventually death.