Vitamins or "amines of life" are a heterogeneous set of organic substances (ESSENTIAL in small quantities) which do NOT provide energy and act with specific functions for:
- The development of the organism
- Proper BIOregulation of metabolic activities
- The constitution of enzymes and coenzymes.
Usually, human needs are measurable in quantities ranging from micrograms (µg) to milligrams (mg) and NOT ALL are present in ALL foods. Sometimes there are "traces" of it while, in other cases, only "precursors" (which need the metabolic conversion of the organism to be activated).
The almost total deficiency of vitamins is called avitaminosis and the partial deficiency hypovitaminosis, but ATTENTION! The excess of vitamins can also cause hypervitaminosis, which is a toxic state due to overdoses, generally of a pharmacological nature.
Vitamins can be recognized by nomenclature or by a letter of the alphabet and are classified according to their chemical characteristics. The most common differentiation is that referred to the solubility in water or in fats:
- Fat-soluble vitamins (soluble in fats): vitamin A (retinol and equivalents), vitamin D (calciferol and equivalents), vitamin E (tocopherols), vitamin K and "vitamin F" (essential fatty acids - AGE).
- Water-soluble vitamins (soluble in water): vit C, vit B1, vit B2, vit PP, vit B5, vit B6, vit H, folati e vit B12.
The water-soluble vitamins, as the term indicates, are soluble in water and, on balance, they are ALL the molecules of group B together with vit. C.
Vitamin C (anti-scurvy)
L-ascorbic acid and dehydroascorbic acid are water-soluble of group C. They are found in fresh fruits and vegetables, such as oranges, lemons, grapefruits, kiwis, strawberries, melons, tomatoes and cabbage. Vitamin C is a powerful antioxidant and therefore also represents a good anti-tumor (especially in a preventive key); keeps blood vessels intact and constitutes a fundamental element for the synthesis of collagen; ascorbic acid regulates the metabolism of calcium (Ca), promotes intestinal absorption of iron (Fe) and determines the conversion of folic acid into folinic acid; it inhibits the synthesis of nitrosamines (carcinogenic compounds) in the digestive tract and is also protective against infectious diseases. Vitamin C is absorbed in the small intestine and deposited in the liver and adrenal glands; the deficiency generates: Scurvy and poor resistance to infections, while the excess causes kidney stones (in subjects predisposed to oxalate stones, see article: diet and kidney stones), diarrhea and dyspepsia.
Vitamin B1 (antiberiberica)
It is a water-soluble vitamin better known as thiamine or aneurine which is found mainly in whole grains (much less in refined ones), in wheat germ, in legumes, in liver, in shellfish and in mushrooms. It is a coenzyme of carbohydrate metabolism, influences the transmission of the nerve impulse and is involved in the metabolism of ethyl alcohol. Vitamin B1 is absorbed in the intestine and deposited in the liver; the deficiency causes Beri-Beri, neuritis and polyneuritis while the pharmacological excess induces shock. They are B1 antivitamins: oxytiamine, juritiamine and thiaminase.
Vitamin B2 (antidermatitis): it is a water-soluble vitamin also called riboflavin and is found in foods: in liver, eggs, milk, fish, whole grains and mushrooms. Vitamin B2 is a constituent of the FAD and FMN coenzymes involved in redox reactions but also participates in the maintenance of the mucosa. It is absorbed in the small intestine and stored in the liver; the deficiency manifests itself with lesions of the skin around the nose and in the edges of the lips and with ocular sensitivity to light, while the excess (if any) is not yet documented.
Vitamin B3 or PP (antipellagrosa)
Nicotinic acid and nicotinamide are water-soluble vitamins of the PP group. Food sources are: liver, poultry, meat, tuna, legumes and milk (it also has a synthetic precursor, the essential amino acid tryptophan). It intervenes in the metabolism of lipids, carbohydrates and proteins, and participates in the formation of coenzymes NAD and NADP. Vitamin PP is absorbed in the intestine and the deficiency causes Pellagra (photosensitive dermatitis, diarrhea and dementia) while the excess causes headache, redness, itching, liver and intestine lesions, and allergies.
Vitamin B5 (for growth)
Also called pantothenic acid, B5 is a water-soluble vitamin found in liver, meat, whole grains, eggs, vegetables and nuts. It is another coenzyme (CoA) important in the metabolism of lipids, carbohydrates and proteins, as well as in the synthesis of cholesterol and steroid hormones. Vit. B5 is absorbed in the small intestine and, in the tissues, is found in the form of CoA; the deficiency is unlikely thanks to its widespread use in food, just as the symptoms and signs of excess are not known. The anti-vitamin of vit. B5 is an antimalarial drug.
Vitamin B6 (antidermatitic)
Pyridoxine, pyridoxal and pyridoxamine are water-soluble vitamins of group B6. The main food sources are: whole grains, liver, spinach, peas and bananas; it is a constituent of coenzymes that participate in the metabolism of amino acids. It is absorbed in the small intestine and is deposited in the liver and brain; the deficiency, although rare, causes skin lesions, convulsions, dizziness and kidney stones, while the excess (if possible) is not yet known.
Vitamin B8 or vitamin H (antidermatitic)
Biotin and α-biotin are water-soluble vitamins of the H group; it is contained in egg yolk, liver, kidney, green vegetables and meat but is also synthesized by the intestinal bacterial flora. It constitutes a coenzyme for the synthesis of fats, amino acids and carbohydrates; it is absorbed in the small intestine and the deficiency causes dermatitis, fatigue, depression, nausea, vomiting, loss of appetite and pain. The deficiency is not known. THERMAL AND PHOTOSENSITIVE.
Vitamin Bc or folic acid (anti-anemic)
It is a water-soluble vitamin also called pteroyl-glutamic acid. It is contained in egg yolk, liver, kidneys, green vegetables, asparagus, wheat germ and legumes. Folic acid is a coenzyme that participates in the synthesis of nucleic acids, and in the reproduction of red and white blood cells. Bc is absorbed in the small intestine; its deficiency determines an anemic form called megaloblastic, as well as changes in the mucous membranes, redness of the tongue and diarrhea. There are no known symptoms of excess. Relative antivitamins are contraceptive and anticonvulsant drugs.
Vitamin B12 or Cobalamin (antianemica)
And there are several types of this water-soluble vitamin, all stored in the liver; it is found in active form exclusively in foods of animal origin: meat, eggs, fish, shellfish, liver, kidneys and milk. It is a coenzyme that has several functions: together with Bc it synthesizes nucleic acids, determines the replication of red blood cells and promotes the functioning of the nervous system; Vitamin B12 is absorbed in the intestine, even if only in a form linked to a mucoprotein secreted in the stomach, the intrinsic factor of Castle. The deficiency causes an anemic form called Pernicious anemia, as well as nervous degeneration and digestive disorders; Vitamin B12 deficiency is common in vegetarians and especially vegans, while the symptoms of excess are not known.
The water-soluble vitamins, with the exception of B2, B6 and partially for B12, are ALL THERMOLABLE. Furthermore, C, B2, B6 and B8 exhibit a fair sensitivity to light while B1 negatively suffers the effect of some preservative agents.
Reserve capacity of some water-soluble vitamins
|RESERVE TIME||DEPOSIT LOCATIONS|
|VITAMIN B1||4 10-days||muscle, liver, brain|
|VITAMIN B2||2 6-weeks||skeletal muscles, liver|
|VITAMIN B3||2 6-weeks||liver|
|VITAMIN B6||2 6-weeks||muscle, liver, brain|
|VITAMIN B9 (folic acid)||3-4 months||liver|
|VITAMIN B12||3 5-years||liver|
|VITAMIN C||2 6-weeks||brain, kidney, adrenal gland, liver|