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Vitamins and avitaminosis Artur Cieślewicz, PhD Department of Clinical Pharmacology [email protected] What are vitamins? • Vitamins – organic substances necessary for life • Essential for normal functioning of body • Cannot be synthesized internally (save for few exceptions) • Necessary for growth, vitality, general well-being Because at one time no one knew the chemical structure of vitamins and therefore could not give them a proper scientific name, most are designated by a letter of the alphabet. • Found in minute quantities in all natural food • Vitamins must be obtained from these foods or from dietary supplements • It is imposible to sustain life without all the essential vitamins 1 • Vitamins cannot replace food, cannot be assimilated without ingesting food • They have no callories or energy value of their own • They are not substitutes for protein or any other nutrients (mineral, fats, carbohydrates, water) • Vitamins themselves are not components of body structures • One cannot take vitamins, stop eating and expect to be healthy • Vitamins regulate metabolism through enzyme systems (coenzymes, cofactors) • A single deficiency can endanger the whole body “Everyone who has in the past eaten processed sugar, white flour, or canned food has some deficiency disease, the extent of the disease depending on the percentage of such deficient food in the diet” Dr Tarnel T. Quigley, The National Malnutrition Vitamins occur in all organic material A well-balanced diet should provide all needed vitamins in sufficent amount Such diet is very difficult to arrange: • most of the foods we eat have been processed and depleted in nutrients • most restaurants tend to reheat food or keep it warm under heat lamps which destroys such vitamins as A, B1 or C. Vitamins can be divided in two groups Water-soluble: Vitamin C, all B vitamins Fat-soluble: Vitamin A, D, E, K 2 Water soluble vitamins • Circulate freely in the blood, watery fluids between cells and in the fluids inside cells • Most of them can move through the bloodstream without needing carriers (only B12 needs a binding protein) • Excesses of water-soluble vitamins are eliminated by kidneys (except folate and B12 which are regulated by liver and released through the bile) Water soluble vitamins • Inactive until they are transformed into their coenzyme form. • All of the watersoluble vitamins can act as important parts of the coenzymes that make enzymatic reactions possible Water soluble vitamins • Water-soluble vitamins are vulnerable to losses during cooking as they can easily leach out into cooking water • Many of these vitamins are sensitive to heat as well • Water-soluble vitamins are not toxic when consumed in food. Supplements of water-soluble vitamins are also not toxic in normal amounts • Exceptions: B3 (only while taken in the form of niacin, which can cause skin flushing) and C (can cause intestinal irritation if taken in large amounts and in the acidic form) 3 Vitamin C (ascorbic acid) • The most widely used vitamin supplement in the world • Lack of vitamin C for long periods of time can result in scurvy • By 1617, John Woodall, a surgeon for the British East India Company, published a cure for scurvy – lemon juice • James Lind wrote Treatise on the Scurvy in 1753: gave some sailors two oranges and one lemon each day, while other sailors received cider, vinegar, or other possible scurvy cures. This may have been the first scientific nutrition experiment in the history of science. He proved that fresh citrus fruit prevented and cured scurvy. Vitamin C (ascorbic acid) • • • • • Until the early twentieth century, the factor in these foods that prevented scurvy was an unknown antiscorbutic (prevents scurvy) factor In 1912, Casimir Funk introduced his theory that scurvy is due to the absence of an “anti-scurvy vitamine.” This factor was named vitamin C in the 1920s Albert Szent-Györgyi isolated a substance he called hexuronic acid (renamed later to ascorbic acid) because it is a six-carbon compound – awarded in 1937 with Nobel Prize in medicine By 1932, vitamin C was isolated and identified, complete with photographs of the vitamin C crystals The ascorbic acid molecule was first successfully synthesized in 1933 MAIN FUNCTION SYNTHESIS OF COLLAGEN! 4 Vitamin C (ascorbic acid) Deficiency of vitamin C is apparent in many body systems. Blood vessels are dependent on vitamin C to maintain their collagen. Bleeding gums and small hemorrhages under the skin can be signs of developing vitamin C deficiency. With severe deficiency, the muscles deteriorate, including the heart muscle. Wounds fail to heal and teeth become loosened because collagen cannot be formed. Infections are common. Death from scurvy can be from internal hemorrhaging. Scurvy is easily reversed with fresh fruit and vegetables. 5 B Vitamins • The B vitamins were identified and isolated early in the twentieth century when refined grains were first found to cause deficiency diseases. • Work so closely together that it is hard to tell which individual B vitamin is missing when a deficiency occurs. • The B vitamins need to be taken together in food or in supplements. B Vitamins • Other nutrients also interact with the B vitamins: a mineral, iron and an essential amino acid, tryptophan, are both needed to synthesize niacin,vitamin B3. • The best way to avoid a deficiency of B vitamins is to eat a varied diet of fresh fruit, an abundance of vegetables, whole grains, legumes, nuts and seeds, and other food as desired. • Some of these B vitamins can also be made by friendly bacteria in a healthy colon and absorbed into circulation. 6 B1 (Thiamin) • First discovered in Japan in the early 1900s, when the lack of thiamin in white rice caused beriberi • First synthesized in 1936 • Found in rice bran and rice germ, both of which are removed when white rice is made from brown rice B1 (Thiamin) Functions: - Promotes growth - Aids digestion, especially of carbohydrates - Improves mental attitude - Keeps nervous system, muscles and heart functioning normally - Helps fight air- or seasickness - Relieves dental postoperative pain - Aids in treatment of herpes zoster 7 B1 (Thiamin) Deficiency: - Common among alcoholics, who often have inadequate food intakes - Alcohol impairs the absorption of thiamin, while increasing excretion of thiamin - Tannins in tea and coffee can oxidize thiamin, reducing the availability of thiamin in the diet - Extreme thiamin deficiency can lead to an enlarged heart, weight loss, muscular weakness, poor shortterm memory, and cardiac failure - If thiamin is absent or too low in the diet for prolonged periods, this can result in beriberi (can cause damage to the nervous system, heart, and muscles) 8 B2 (Riboflavin) • Discovered as a growth factor in the early nineteenth century • Has a greenish-yellow color, which led to one of its early names, vitamin G. • In 1935, riboflavin was first synthesized in the lab, and by 1938, its structure was determined • When taken in excess of needs, riboflavin is responsible for the bright yellow color of urine B2 (Riboflavin) Functions: - Aids in growth and reproduction - Promotes healthy skin, nails, hair - Helps eliminate sore mouth, lips and tongue - Benefits vision, alleviates eye fatigue - Functions with other substances to metabolize carbohydrates, fats and proteins - Works as a part of FAD and FMN coenzyme: reduction and oxidation cycle of glutathione, activation of pyridoxine, TCA B2 (Riboflavin) Deficency: Ariboflavinosis: inflammation of the membranes of the eyes, the mouth, the skin, and the gastrointestinal tract. Also can cause sensitivity to light. Cracks on the side of the mouth are another possible sign of riboflavin deficiency. Other symptoms: sore throat with redness and swelling of the mouth and throat mucosa, glossitis (magenta tongue with atrophy) 9 10 B3 (Niacin) • Can be found in two different forms: niacin (nicotinic acid) and niacinamide (nicotinamide); nicotinic acid can be easily converted into nicotinamide in the body • Niacin is used in two coenzyme forms: NAD and NADP, which are required by hundreds of enzymes • Niacin can be made in the body from tryptophan B3 (Niacin) Functions: Helps reduce cholesterol and triglicerides Aids in metabolizing fats and promoting a healthy digestive system Gives healthier looking skin Helps prevent and ease severity of migraine headaches Increases circulation and reduces high blood pressure Eases some attacks of diarrhea Reduces the unpleasant symptoms of vertigo in Meniere’s disease Increases energy through proper utilization of food Helps eliminate canker sores and bad breath B3 (Niacin) Deficency: The deficiency disease is called pellagra. Pellagra is characterized by the four Ds: diarrhea, dermatitis, dementia, and death. Pellagra killed thousands of people in the South in the early twentieth century who were eating a diet consisting of mostly corn. Most of the niacin in corn is unavailable for easy assimilation, and corn is also low in tryptophan. In Mexico, pellagra is rare even in people on low-protein corn diets because the corn is soaked in lime before the tortillas are cooked. This process releases the niacin for absorption. 11 Biotin • Originally reffered as vitamin H • Discovered in late 1930s when animals developed skin problems when fed only with egg whites • It took forty years of research to confirm biotin as a B vitamin because deficiency is so rare. • Can be synthesized only by bacteria, algae, yeasts, molds, and a few plant species. 12 Biotin • Coenzyme in four important carboxylases: – Acetyl-CoA carboxylase helps make fatty acids – Pyruvate carboxylase helps make blood sugar from fats and protein – Methylcrotonyl-CoA carboxylase helps metabolize the amino acid leucine – Propionyl-CoA carboxylase helps burn fats Biotin Functions: - Aids in keeping hair from turning gray - Helps in preventing treatment of baldness - Eases muscle pains - Alleviates eczema and dermatitis Biotin • • • • • Deficency has been noted in prolonged intravenous feeding where biotin was omitted Also from long-term consumption of raw egg whites (Biotin can bind to avadin, a protein found in egg whites. Cooking inactivates this bond, so cooked egg whites do not bind biotin.) Deficiency can result from a genetic lack of biotinidase, an enzyme that releases biotin from small proteins. Rare hereditary disorder. Deficiency symptoms: eczema of face and body, extreme exhaustion, impairment of fat metabolism, anorexia, alopecia, depression Usually deficiency of biotin is very rare because it is synthesized by bacteria living in healthy large intestines (the wall of large intestine has a specialized process for the uptake of biotin) 13 B5 (pantothenic acid) • Has been found in every living cell (plant and animal tissues and microorganisms) • Identified in 1933 by Roger William as a growth factor for yeast • Forms a large part of the coenzyme A molecule. B5 (pantothenic acid) Functions - Vital for proper functioning of adrenal glands - Essential for convertion of fat and sugar to energy - Necessary for synthesis of antibodies, utilization of PABA and choline - Aids in wound healing - Fights infections (synthesis of antibodies) - Treats postoperative shock - Prevents fatigue - Reduces adverse and toxic effects of many antibiotics - Lowers cholesterol and triglicerides 14 B5 (pantothenic acid) Pantothenic acid deficiency is very rare and seen only in cases of severe malnutrition. Pantothenic acid is found in many common foods and average diets are thought to have an adequate amount of it. Pantothenic acid is also made by the normal bacteria that live in the colon. Deficiency symptoms: hypoglycemia, duodenal ulcers, blood and skin disorders. 15 B6 (pyridoxine) • Discovered in the 1930s • A group of closely related substances (pyridoxine, pyridoxal, pyridoxamine), all of which can be converted to the most active coenzyme form, Pyridoxal Phosphate (PLP) • Extensively stored in muscle tissue because PLP is a coenzyme to the enzyme glycogen phosphorylase, catalizing the release of glucose from glycogen • Depleted by alcohol drinking B6 (pyridoxine) Functions: - Takes part in the synthesis of many neurotransmitters (serotonine, dopamine, GABA, norepinephrine) - Serves as a coenzyme in the synthesis of nucleic acids - Must be present for the production of antibodies and red blood cells - Required for the proper absorption of B12 - In combination with folic acid can help break down homocysteine, significantly lowering the risk of heart disease - Strenghthens the immune system - Takes part in the convertion of tryptophan to niacin - Helps reduce dry mouth and urination problems caused by tricyclic antidepressants B6 (pyridoxine) Deficiency: - causes depression and confusion (brain wave abnormalities and convulsions in extreme deficiency) - Anemia, seborrheic dermatitis, glossitis 16 Folate • Isolated from spinach in 1945 • Known also as Bc or vitamin M • Primary coenzyme form: TetraHydroFolate (THF) – needed to transfer one-carbon units • Synthetic folic acid from supplements has a higher bioavailability than the naturally occurring folates 17 Folate Functions: - Essential for the formation of red blood cells - Important for the production of nucleic acids - Essential for the division of body cells - Needed for utilization of sugar and amino acids - Lowers homocysteine levels, reducing the risk of heart disease - Protects against birth defects (neural tube defects) - Improves lactation - Protects against intestinal parasites and food poisoning - Promotes healthier looking skin - Act as an analgesic for pain - Act as a preventive for canker sores - Helps ward off anemia Folate Deficiency: - Lack of folate in the diet can cause neural tube defects in an embryo of a pregnant woman - Deficiency signs include anemia and deterioration of the gastrointestinal tract - The anemia results from abnormal blood cell division resulting in fewer and larger red blood cells (megaloblastic anemia) - Other symptoms are: weakness, sore tongue, head aches, heart palpitations, irritability and behavioral disorders Folate Deficiency: - Folate deficiency can be caused by inadequate absorption, inadequate consumption, or unusually high metabolic needs for this vitamin - Drugs that can interfere with folate include aspirin, anticancer drugs, antacids, and oral contraceptives - Older people tend to have higher homocysteine levels and are encouraged to meet or exceed the RDA for folate 18 B12 (cobalamine) • • • • • • • • Discovered in 1930s simultaneously by two research teams The only vitamin that conatins mineral elements (cobalt) Chemical structure revealed in 1956 The most complex vitamin Coenzyme forms: methylcobalamine and deoxyadenosyl cobalamine Commonly known as „red vitamine” (as it is a red crystalline compound) Not well assimilated through stomach (needs to be combined with calcium during absorption) Can be stored in the body (it’s up to 3 years to deplete this supply) 19 B12 (cobalamine) Functions: - required for the synthesis of hemoglobin - needed for DNA synthesis in the rapidly dividing cells of the bone marrow - Helps break down homocysteine, lowering the risk of heart disease - Promotes growth and increases apetite in children - Maintains healthy nervous system - Relieves irritability, improves concentration, memory and balance - Helps protect against smoking-induced cancer B12 (cobalamine) Deficiency: - Usually not from lack of intake, but rather from lack of absorption - Lack of vitamin B12 or folate can lead to the production of large, immature, hemoglobin-poor red blood cells (pernicious anemia, most common in those over 60 years of age) - Folate cannot be properly utilized if vitamin B12 is low or absent - If folate or vitamin B12 is absent, symptoms of folate anemia can be present (slowed DNA synthesis, which shows up first as defective red blood cells) - Deficiency of vitamin B12 first shows as a paralysis that begins in the extremities and moves inward 20 Fat-soluble vitamins • Vitamins A, D, E, and K • Are found in the liver and the fatty tissues of the body where they are stored and used • Require bile in order to be absorbed into the lymph system from the intestines Vitamin A • 300 B.C.: the Hippocratic School of Medicine recommended liver (rich in vitamin A) for children with night blindness or infections • Vitamin A was the first vitamin discovered • In 1907, the fat-soluble vitamin A was found necessary for growth • In 1930 it was learned that there were two related forms: beta-carotene and a fat-soluble Vitamin A • Vitamin A was first synthesized in 1947 • Most of the vitamin A in the body is stored in the liver in the form of retinyl palmitate 21 Vitamin A Functions: - Antioxidant activity (beta-carotene) - Counteracts night blindness, weak eyesights; aids in the treatment of many eye disorders - Builds resistance to respiratory infections - Keeps the outer layers of tissues and organs healthy - Helps in the removal of age spots - Promotes growth, strong bones, healthy skin, hair, teeth and gums - Helps treat acne, superficial wrinkles, impetigo, boils, carbuncules and open ulcers when applied externally - Aids in the treatment of emphysema and hyperthyroidism Vitamin A - Severe vitamin A deficiency is one of the leading causes of blindness in children: - 11-cis-retinal is required for the production of rhodopsin in rods - retinoic acid is required for the maintenance and integrity of the corneal epithelium - Over half of a million children lose their sight each year from severe vitamin A deficiency. - The blindness results from a lack of vitamin A in the cornea of the eye (xerophthalmia). - In the first stage of xeropthalmia, the cornea becomes hard and dry, (xerosis). - Xerosis can progress to a softening of the cornea that can lead to irreversible blindness. 22 Vitamin A • Other effects – vitamin A deficiency results in multiple abnormalities in innate and adaptive immunity – all epithelial tissues are sensitive to a lack and excess of vitamin A; deficiency in skin appears as dryness – teratogenicity: excess or deficiency causes birth defects or the death of the embryo; therefore, in 2005 the FDA approved new regulations including the registry of all patients to whom retinoids were prescribed – Acute Promyelocytic Leukemia: beneficial effect of introducing all-trans-retinoic acid to the therapy; however, in some cases retinoic acid syndrome was developed (fever, respiratory distress, changes in hemostasis, and acute renal failure) 23 Vitamin D (calciferol) • • • • • • First named in 1922 by researchers who learned of a fat-soluble substance that played an important role in bone growth In 1931 vitamin D2 was synthesized, and the structure of vitamin D was established by 1936 More accuratly: vitamin D is a prohormone – must be metabolized to a biologically active form that functions as a steroid hormone Main function: regulating calcium and phosphorus to make bones strong Is necessary in the diet only for people who get too little sun to make their own vitamin D very hard to find in a natural diet as it occurs in only a few foods (it is present in unfortified foods in only very small and variable quantities) Vitamin D (calciferol) Functions: - Properly utilizes calcium and phosphorus necessary for strong bones and teeth - Taken with vitamins A and C can aid in preventing colds - Helps in treatment of conjunctivitis - Aids in assimilating vitamin A - Aids the functioning of the immune system 24 Vitamin D (calciferol) - Deficiency: rickets, severe tooth decay, osteomalacia, senile osteoporosis - A deficiency of vitamin D makes it difficult to keep enough calcium in the bloodstream → releasing calcium from bones - Severe deficiency of vitamin D in childhood: the bones fail to mineralize properly → the arms and legs become bowed (rickets) Vitamin D (calciferol) - Deficiency: rickets, severe tooth decay, osteomalacia, senile osteoporosis - A deficiency of vitamin D makes it difficult to keep enough calcium in the bloodstream → releasing calcium from bones - Severe deficiency of vitamin D in childhood: the bones fail to mineralize properly → the arms and legs become bowed (rickets) - In very severe cases, low levels of blood calcium affect the nerves 25 Vitamin E (tocopherol) • Discovered at the University of California at Berkeley in 1922, where it was found to be essential to maintain fertility • Pure alpha-tocopherol was first isolated from wheat germ oil in 1936 • The tocopherols are divided into four types: alphatocopherol, beta-tocopherol, gamma-tocopherol, and delta-tocopherol • Also in the vitamin E family are the very similar tocotrienols (alpha-, beta-, gamma-, and delta-tocotrienol) • All tocopherols and all tocotrienols have the ability to donate a hydrogen atom to neutralize free radicals – However, only α-tocopherol provides vitamin E biologic activity in humans Tocopherol structures Vitamin E (tocopherol) Functions: - The main role: an antioxidant to neutralize free radicals in cell membranes, in mitochondrial membranes, and in LDL - Enhances activity of vitamin A - Important as vasodilator and anticoagulant - Protects lungs from air pollution by working with vitamin A - Helps to prevent various forms of cancer - Prevents and dissolves blood clots - Alleviates fatigue - Accelerates healing of burns - Lowers risk of ischemic heart disease and stroke - Decreases risk of Alzheimer’s disease 26 Vitamin E (tocopherol) Deficiency: - Occurs rarely, virtually never as a result of dietary deficiency: - Genetic defect in α-tocopherol transfer protein - Genetic defect in lipoprotein synthesis - Fat malabsorption syndromes - The primary manifestations of human vitamin E deficiency include spinocerebellar ataxia, skeletal myopathy, and pigmented retinopathy - Earliest observed symptom is hypo- or a-reflexia 27 Vitamin K • Discovered by a Danish scientist, Henrik Dam, in the late 1920s: he discovered a factor that was causing excessive bleeding and was missing from some diets; called the new coagulation vitamin Koagulationsvitamin • Fat-soluble vitamin needed for blood coagulation • There are 3 forms of vitamin K: K1 (phylloquinone, synthesized by plants), K2 (menaquinone, synthesized by bacteria) and K3 (menadione, synthetic; in USA forbidden by FDA due to potential toxicity in human use) Vitamin K Functions: - Is necessary for the liver to synthesize prothrombin - Needed to enable osteocalcin to bind minerals to bones - Helps in preventing internal bleeding and hemorrhages - Aids in reducing excessive menstrual flow - Promotes proper blood clotting Vitamin K • Healthy adults rarely have a deficiency of vitamin K, because it is abundant in food and in addition, the bacteria in the large intestine synthesize vitamin K2. Moreover, vitamin K can be used over and over again in a conservation cycle. • Vitamin K-responsive hemorrhagic events were observed in patients receiving antibiotics (e.g., some 2nd and 3rd generation cephalosporins) • Symptoms of vitamin K deficiency include nosebleeds, bleeding gums, prolonged bleeding from cuts, or blood in the urine or stool 28 Vitamin K • Infant vitamin K deficiency can cause intracranial hemorrhage (bleeding inside the skull) and can be life-threatening. As many as one in five thousand infants may develop vitamin K deficiency bleeding unless supplemental vitamin K is given. • Newborns may be deficient in vitamin K, because: – Vitamin K levels in breast milk are low – Bacteria to make vitamin K in the large intestine may not yet be ready. – The vitamin K conservation cycle may not be developed • Because of these reasons, newborn infants are routinely given an injection of 1000 mcg of vitamin K1 Literature Blake S.(2008) Vitamins and minerals demystified. Mindell E. (1999) Earl Mindell’s vitamin bible for the twenty-first century 29 Thanks for your attention 30