Vitamins Part 1 PDF

Water Soluble Vitamins Chapter 8  Vitamins - General Casmir Funk (1911) - Lister Institute in London, England Recognized that there were substances in foods that were “vital to life” - called these substances vitamins - Vita – life - Amine – containing nitrogen (NH2) (...

Water Soluble Vitamins Chapter 8  Vitamins - General Casmir Funk (1911) - Lister Institute in London, England Recognized that there were substances in foods that were “vital to life” - called these substances vitamins - Vita – life - Amine – containing nitrogen (NH2) (note: the first vitamins discovered contained N, however, we now know that NOT all vitamins contain N – but we still call them vitamins) 2  Vitamins - General Vitamins are organic compounds that are essential in the diet in small amounts to promote and regulate the processes necessary for growth, reproduction, and the maintenance of health. 3  Vitamins - General The ability to isolate and purify vitamins has allowed them to be added to the food supply (fortification/enrichment) and incorporated into pills (supplements). Fortification: addition of nutrients to foods Enrichment: nutrients added to a food to restore those lost in processing The modern diet includes vitamins: – that are naturally present in foods – those that have been added to foods – those consumed as natural health products 4 5  Vitamins in Foods Protein Foods Thiamin Riboflavin Vegetables Niacin and Fruits Biotin Riboflavin Pantothenic acid Niacin Folate Vitamin B6 Vitamin B12 Folate Vitamin A, D, K Vitamin C Vitamin A Whole Grain Foods Vitamin E Thiamin Vitamin K Riboflavin Niacin Pantothenic acid Vitamin B6 Folate Healthy Fats: Vitamin A, E, K 6  Water Soluble Vitamins Vitamin C (ascorbic acid) B complex group Thiamin (B1) Riboflavin (B2) Niacin (B3) Pantothenic acid (B5) B6 (pyridoxine) Biotin Folate (folic acid) B12 (cobalamin) 7  B Vitamins – Function 1.) B vitamins function as part of coenzymes to help get energy from CHO, fats, and protein Do not produce energy but are termed ‘energy releasing vitamins’ - Thiamin - Riboflavin - Niacin - Pantothenic acid - Vitamin B6 - Biotin 2. some B vitamins are necessary for RBC formation and are called hematopoietic vitamins – Vitamin B12 and folate 8 Coenzymes: The active coenzyme form of a vitamin is necessary for enzyme activity and acts as a carrier of chemical groups or electrons in the reaction. 9  Function of B vitamins: Coenzyme Action Enzyme Enzyme Enzyme Enzyme Active site Coenzyme CD Compounds CD Vitamin B C D A A Vitamin CD B A B Coenzyme New products A B Active site Enzyme Enzyme Enzyme Enzyme Without coenzymes, With the coenzymes in... and the reactions The reactions are compounds A, B, and place, compounds are proceed completed with either CD don’t respond to attracted to their instantaneously. the formation of a their enzymes. sites on the enzymes... The coenzymes new product, AB, or often donate or accept the breaking apart Active site: where the reaction takes place electrons, atoms, or of a compound into groups of atoms. two new products, C and D, and the release of energy. Vitamins form part of the coenzyme allowing the enzyme to make or dismantle compounds. An enzyme cannot function without its coenzyme, stressing the importance of B vitamins in the diet.  Thiamin (B1) - History Late 1800’s - Takaki (Japanese naval officer) - his navy was plagued with a disease called beri beri - he added milk and meat to their diet and symptoms disappeared (weakness, fatigue, depression) - thought that beri beri was due to a protein deficiency (note: their diet consisted mainly of refined polished rice (outer husk removed – no fibre) 11  Thiamin (B1) - History 1897 - Eijkman (Dutch physician) Tried to find a cure for beri beri Recognized that chickens fed a diet of refined rice produced the same symptoms as humans with beri beri (weakness, fatigue, depression) Found that symptoms disappeared when rice husks and bran were added to the chickens diet 12  Thiamin (B1) - History 1936/37 – chemical structure was determined – Sulphur – Amino group – B1 was called Thiamin thi – greek for sulphur amine –amino group 13 Thiamin: Chemistry and Properties Water soluble Destroyed by cooking or storage because it’s sensitive to: – Heat – Oxygen Canadian regulations: thiamin must be added to: white flour and pastas labelled as enriched (e.g., bread, spaghetti) Infant formula Simulated meats and egg products Instant breakfasts Meal replacement products 14  Function of Thiamin: Metabolism Main Function: Thiamin is part of the coenzyme TPP required to get energy from CHO, fats, protein Thiamin pyrophosphate (TPP) TPP is needed for 2 major reactions: pyruvate ---- acetyl CoA + CO2 -ketoglutarate ---- succinyl CoA + CO2 (Kreb’s cycle) 15  Another Function of Thiamin Thiamin triphosphate (TTP) - absence of this form will produce symptoms of beri beri - TTP is part of nerve cells (brain, heart, muscles) therefore is required for nerve functioning Thiamin also assists in the conversion of tryptophan to niacin 16  Clinical Deficiencies of Thiamin Deficiency - Beri Beri - 4 forms 1. Infantile (infants) 2. Wet (severe edema) 3. Dry (muscle wasting, leg cramps) 4. Cerebral (Wernicke-Korsakoff Syndrome) – severe thiamin deficiency due to excess alcohol consumption because alcohol interferes with thiamin. Symptoms: - staggering gait - mental confusion - loss of short-term memory 17 Wet Beri Beri The impression of the thumb remains on the leg. Dry Beri Beri In Sri Lanka, the word beriberi means “I cannot” referring to the extreme weakness and depression that are the earliest symptoms of dry Beri Beri 19 Thiamin (B1): Best food sources: Pork and whole grains 20  Riboflavin (B2) - History 2nd B vitamin to be discovered Another name: Vitamin B2 soluble in water destroyed by light – opaque milk containers are used to prevent decomposition of riboflavin in milk 21  Riboflavin (B2) Canadian regulations: riboflavin must be added to: White flour and pastas labelled as enriched (e.g., bread, spaghetti) Infant formula Simulated meats, egg products Instant breakfasts 22  Function of riboflavin(B2) Main Function: Riboflavin is part of the coenzymes FMN and FAD that are required to get energy from CHO, fats, protein combines with phosphoric acid to become part of the structure of 2 flavin coenzymes i) FMN - flavin mononucleotide ii) FAD - flavin adenine dinucleotide 23  Riboflavin Coenzyme, Accepting and Donating Hydrogens FAD FADH 2 During the Kreb’s cycle, FADH 2 carries the hydrogens to the electron transport chain. At the end of compounds release hydrogens, the ETC, the hydrogens are accepted and the riboflavin coenzyme FAD by oxygen, creating water, and FADH2 picks up two of them. As it accepts becomes FAD again. For every FADH2 two hydrogens, FAD becomes that passes through the ETC, 2 ATP FADH 2. are generated.  Deficiency of Riboflavin (B2) Deficiency disease is called: Ariboflavinosis Symptoms i) cheilosis – Cracks in the skin and at the corner of the mouth ii) glossitis – Swollen tongue due to atrophy of the tissue iii) ocular disorders – Formation of extra blood cells in the eyes – Itchy eyes – Eyes are sensitive to light 25  Riboflavin deficiency: Glossitis In a riboflavin deficiency, the tongue A healthy tongue has a rough and becomes smooth and swollen due to somewhat bumpy surface. atrophy of the tissue. Riboflavin: Best Food Sources: Milk and Milk Products 27  Niacin (B3) History: 3rd B vitamin to be discovered Other names: Nicotinic acid Nicotinamide Niacinamide Vitamin B3 Major discovery: – Niacin cured a disease called pellagra – This contradicted the belief that diseases were only caused by infections – This proved that an inadequate diet lacking in vitamins can cause diseases 28  Chemistry/Properties of Niacin Water soluble Canadian regulations: niacin must be added to: white flour and pastas labelled as enriched (e.g., bread, spaghetti) Infant formula Simulated meats and egg products Instant breakfasts Meal replacement products 29  Properties of Niacin Tryptophan is its precursor (a substance from which another substance is made) What is tryptophan? (we don’t need niacin in our diet providing we have enough tryptophan) The conversion of tryptophan to niacin requires: i) thiamin ii) riboflavin iii) vitamin B6 (pyridoxine) 1 mg niacin = 60 mg tryptophan 1 mg niacin = 1NE (RDA are expressed as mg of NE) How many mg of tryptophan are there in 2 NE? 30  Physiological Function of Niacin Niacin functions in the body as a component of 2 coenzymes i) NAD - nicotinamide adenine dinucleotide ii) NADP - nicotinamide adenine dinucleotide phosphate Main Function: Niacin functions in the body as a component of the coenzymes NAD, NADP that are required to get energy from CHO, fats, protein 31  Clinical Deficiency of Niacin Pellagra 1) dermatitis - effect on the skin (rash,dry skin, skin darkens and flakes) 2) diarrhea - effect on the GI track (intestines become inflamed) 3) dementia - effect on mental behavior (mental confusion), before pellagra was cured, individuals were put a ‘psychiatric institution’) 4) death - if not cured Pellagra is a “mixed deficiency” – thiamin, riboflavin, and B6 may also contribute to its development 32 Niacin and Pellagra Dermatitis of pellagra: cracked, inflamed skin darkens and flakes away. Commonly occurs on areas of the body exposed to sunlight. Niacin and Pellagra The niacin found naturally in corn (and to a lesser extent in other cereal grains) is bound to other molecules and therefore not well absorbed. The treatment of corn with lime water during the preparation of tortillas improves niacin bioavailability and has helped prevent pellagra in Mexico and other Latin American countries. 34  Toxicity of Niacin Nicotinic acid form causes: vasodilation of vessels - flushed skin 75 mg or more, known as the niacin flush pharmacological doses 3 g or more/day are given to individuals with CVD to lower serum cholesterol and decrease LDL’s Side Effects of megadosing - irregular heart beat, flushing of the skin (“hot flashes”), GI disorders 35 Niacin (B3) Best food sources: protein rich foods 36  Biotin Early during its discovery, biotin was also called Coenzyme R, Vitamin B7, and Vitamin H (Vitamin H and B7 are still used on websites). Biotin is now referred to as Biotin Soluble in water Contains sulphur (like thiamin) Main Function: - serves as a coenzyme to get energy from CHO, fats, protein 37  Biotin Deficiency: none, very rare However, the protein avidin (found in raw egg whites) interferes with biotin absorption Avidin combines with biotin and prevents it from being absorbed However, you’d have to eat more than 24 raw egg whites per day, over several months to develop a biotin deficiency!!! Avidin is denatured up cooking, therefore no effect on biotin if eggs are cooked Early during it’s discovery, rats who were fed raw egg whites developed dermatitis (dry skin) and developed hair loss – For this reason, supplements are sold to improve nails and to prevent hair loss 38  Biotin Deficiency: none Toxicity: none DRI: AI of 30 g/day Dietary sources: found in most foods (liver, egg yolks, yogurt, nuts are good sources) Eating a variety of foods prevents a deficiency Can also be produced by bacteria in the GI tract 39  Pantothenic Acid Another name: Vitamin B5 The name pantothenic acid came from the Greek word pantothen – meaning from everywhere – Dietary Sources…....all foods Susceptible to damage by exposure to heat and low-or-high acid conditions No RDA, an AI of 5 mg/day (sufficient to replace urinary losses) 40  Pantothenic Acid Main Function – part of a coenzyme (CoA) to get energy from CHO, fats, protein – Supplements are sold to help boost energy (Does supplementation work for increasing energy?) Early in it’s discovery (1930’s), research found that a deficiency of pantothenic acid in rats caused fur to turn grey – Supplements are sold to help hair from turning grey (humans)….. Is this possible? 41  Pantothenic Acid No known deficiency --- Why? Toxicity (only with supplements) 10 – 20 grams/day (or more) can cause diarrhea 42 Pantothenic Acid Food Sources: All Foods 43  Vitamin B6 B6 is a complex of 3 closely related compounds: - pyridoxine ( alcohol) - pyridoxal (aldehyde) - pyridoxamine (amine group) Pyridoxine is used to refer to all 3 forms, but the preferred designation is Vitamin B6 Soluble in water Destroyed by light Canadian regulations: Vitamin B6 must be added to: Simulated egg products Meal replacement products 44  Vitamin B6 – Functions/Deficiencies 1. Main Function: part of coenzymes to get energy from carbohydrate, fats and protein After absorption, all 3 forms are converted to its coenzyme form called pyridoxal phosphate (PLP) Particularly important for protein and amino acid metabolism. Therefore, supplements are sold to enhance muscle strength (do the supplements work?) 45  Vitamin B6 – Functions/Deficiencies 2. Required to convert tryptophan to niacin 3. Required to convert tryptophan to serotonin (neurotransmitter - transmits nerve signals to the brain) – Deficiency – depression, confusion – Supplements are sold to treat both depression and aggression (don’t take supplements unless diagnosed!!) 4. Required in the formation of hemoglobin (required to make red blood cells) – Deficiency – anemia 46  Vitamin B6 – Functions/Toxicity 5. Involved in central nervous system functioning Although B6 is a water-soluble vitamin, taking more than 2 grams/day (2,000 mg/day) can cause toxic concentrations in the body, which can affect the CNS (not from diet, usually from excessive supplementation) Symptoms: – Irreversible nerve damage causing numbness and muscle weakness 47  Vitamin B6 – Functions/Claims Vitamin B6 is involved in many biochemical reactions in the body The supplement industry “exaggerates” its effectiveness by emphasizing deficiency symptoms. Many claims are made to help prevent and/or cure many health problems – Do we need a supplement? Or can we get enough Vitamin B6 from our diet? 48 Vitamin B6 Best Food Sources: Protein Rich Foods 49  Folate Other names: Folic acid Folacin PGA (pteroylglutamic acid, named because of its structure) Vitamin B9 (not another name but found on websites) 50  Folate: History It’s been known for over 100 years that anemia often occurs during pregnancy. 1937 – Dr. Lucy Wills, successfully treated a pregnant woman with anemia a yeast preparation, now named Wills Factor Wills Factor was later isolated from spinach and named folate, after the Latin word for foliage (meaning leaf) What is a dietary source of folate? 51  Folate Canadian regulations: Folate must be added to: White flour (e.g. bread) Cornmeal Pasta Also added to cereals 52  Folate: Function THF (tetrahydrofolate) is a coenzyme to get energy from carbohydrate, fats and protein Especially important in protein metabolism 53  Folate –Function and Deficiency - Function: Part of coenzymes to help make DNA for new cell growth - Deficiency: red blood cells don’t divide therefore anemia results (megaloblastic anemia, larger but fewer RBC) 54  Folate: Deficiency ` Deficiency: spina bifida – The neural tube develops into the brain and spinal cord. – If folate is inadequate during the neural tube closure, neural tube defects such as spina bifida may occur in the developing baby (occurs during the 1st trimester of pregnancy) 55 Decreasing spina bifida rates since folate fortification in cereals (1996) 56 Folate Fortification/Toxicity? Some studies have shown an increase in colon cancer since folate fortification began in 1998. This maybe the result of folate stimulating DNA synthesis and promoting growth of pre-existing cancerous cells. When considering food fortification, it is important to consider that what may benefit one segment of the population may harm another segment. 57  Folate – Deficiency/Toxicity Because of folates importance in new cell growth, it is required for brain development Some research has shown that high levels of folate (800 g/day) may help Alzheimer’s patients improve memory, reduce memory decline, or prevent the disease – Supplements are marketed as a “brain booster” for healthy individuals (improve memory) (Will supplements improve your memory?) Toxicity: Not from food Excess supplementation, may mask a vitamin B12 deficiency (because folate chemically reacts (or works with) vitamin B12…..more research is needed. (UL: Do not exceed 1,000 g/day of folate) 58  DRI (RDA) - Folate Adults: 400 g/day Pregnant women: 600 g/day Lactating women: 500 g/day Upper Level: 1000 g/day (1 gram/day) 59 Dietary Sources of Folate 1 cup Spinach: 109 ug 1 Avocado: 113ug 6 spears asparagus: 131ug ½ cup Legumes: 100ug 1 cup OJ: 75ug 1 spear Broccoli: 90ug Raisin bran cereal (1 cup) (fortified): 60 ug per Skim milk (1 cup): 12 ug ½ cup beans: 14 ug Oat bran bagel: 112 ug Best dietary sources: green vegetables 1 cup Lentils: 375ug 60 Dietary Sources of Folate in Foods 61  Vitamin B12 - History 1926 – Researchers treated a disease called pernicious anemia 1940’s – Drs. Minot and Murphy thought that there must be some nutrient in liver that cured pernicious anemia, so they gave patients a pound of liver a day to eat!!! Drs. Minot and Murphy were awarded the Nobel Prize for curing pernicious anemia with a diet containing large quantities of liver, which is very high in Vitamin B12 Later, the substance in liver was extracted and was injected into patients 1956 – the structure of B12 was determined Since it contained cobalt, it was called cobalamin 1973 - synthesized 62  Vitamin B12 Canadian regulations: Vitamin B12 must be added to: Simulated meat and egg products Meal replacement products Infant formula 63  Absorption/Metabolism B12 Absorption requires: - calcium - intrinsic factor called “Castle’s” intrinsic factor or intrinsic factor (intrinsic factor – a protein produced in the stomach that is needed for the absorption of B12) Liver stores 2,000 g (2.0 mg), which is much higher than what the body needs This is how Vitamin B12 differs from the other water soluble vitamins 64 64  Vitamin B12 Main Function: Part of coenzymes to help make DNA for new cell growth Deficiency: pernicious anemia due to B12 deficiency and the lack of the intrinsic factor since B12 in foods combine with the intrinsic factor (gastric) to allow for absorption and transport, red blood cells won’t mature Treatment requires B12 injections (usually monthly, why injections?) 65 Absorption of Vitamin B12 66 Vitamin B12 Deficiency: Normal and Anemic Blood Cells Normal blood cells. The size, shape, and color of the red blood cells show that they are normal. Blood cells in pernicious anemia are called megaloblastic (large but fewer than normal) Megaloblastic blood cells are: - slightly larger than normal red blood cells - shapes are irregular 67  Vitamin B12 Toxicity: none Dietary Sources: animal products Vegans require supplements (not every day because the liver stores a lot) or fortified foods with B12 Because Vitamin B12 causes anemia, supplements, particularly as injections, have been promoted as a “pick- me-up” for tired individuals. There are NO proven benefits of Vitamin B12 supplementation in individuals who are NOT Vitamin B12 deficient 68 Dietary Sources of Vitamin B12: Animal Products 69  Choline: A “new” essential vitamin? Choline: A water soluble compound used by the body to synthesize acetylcholine (a neurotransmitter) and a variety of phospholipids (such as lecithin) needed for cell membrane structure; also required for muscle control The body can make choline in sufficient amounts when it is taken up by intestinal cells and reconstituted into lecithin molecules 70  Choline Research: healthy men developed liver damage when fed a choline-free diet Research: Humans fed IV solutions that did not contain choline developed fatty livers and liver damage Therefore, Institute of Medicine designated choline as an essential nutrient To date: researchers do not know if choline is an essential nutrient, but state that some people may be at risk Although choline is considered a vitamin to some, it is now better known as a conditionally essential nutrient. 71  Vitamin B Impostors Inositol and Lipoic acid These are marketed as B vitamins but are NOT B vitamins They can be made by the body and are abundant in foods, therefore they are non-essential nutrients 72 72  Other nutrient imposters Vitamin P also called hesperidin Coenzyme Q10 also called ubiquinone (quinones are part of the Vitamin K group, this is not one of them) Vitamin B5 - just another name for pantothenic acid Vitamin B15 – also called pangamic acid Vitamin B17 - also called laetril, an alleged cancer cure Vitamin O – oxygenated salt water!!! Vitamin BT – carnitine (transports LCFA for oxidation (metabolism); produced in the body from methionine and lysine, therefore NOT required in the diet (and NO scientific evidence to support the claim that it enhances muscle development) Many others 73  Metabolic Pathways Involving B Vitamins Glycogen Glucose Some amino acids Pyruvate Some amino acids Some amino acids Acetyl-- Fat Some amino acids TCA Cycle Yields energy Other compounds Yields Yields energy energy 74