Module 8 - Water-Soluble Vitamins_student.pdf

KIN275 Introduction to Nutrition Module 8 Water-Soluble Vitamins Julia Totosy de Zepetnek, PhD Module 8 Learning Objectives 1. Introduce vitamins and describe the key features of water vs. fat-soluble vitamins 2. List the major physiological functions of each water-soluble vitamin Discuss DRIs and i...

KIN275 Introduction to Nutrition Module 8 Water-Soluble Vitamins Julia Totosy de Zepetnek, PhD Module 8 Learning Objectives 1. Introduce vitamins and describe the key features of water vs. fat-soluble vitamins 2. List the major physiological functions of each water-soluble vitamin Discuss DRIs and identify major food sources (& any interactions) Discuss major symptoms and diseases associated with deficiency and toxicity Introducing Vitamins First defined in 1912 – Polish chemist Casimir Funk coined the term vitamine (vita = necessary for life; amine = a type of nitrogen-containing substance) after discovering a substance [now known as thiamin] in an extract made from rice bran Term later modified to vitamin (not all are amines) Complex organic compounds that regulate certain metabolic processes Understanding Vitamins Vitamins are organic compounds essential in the diet to promote normal functioning, growth, and maintenance Similar to macronutrients Organic (carbon containing) Different to macronutrients Daily needs of vitamins are small (~1-2mg) Individual units (vs. long chains of smaller units) Not a source of energy …but play crucial roles in reactions that extract energy from macronutrients (coenzymes!) Sources of Vitamins Plants, animals, fungi [and even bacteria!] supply natural forms of vitamins in our diets – Microbiota produce certain vitamins (e.g., biotin, vit K) that can be absorbed to some extent Vitamin supplements are another source Not necessary to consume 100% of every vitamin every day – If healthy and follow an nutritionally adequate diet, cells should contain a supply of vitamins that can last for days or years [depending on the vitamin] Bioavailability of Vitamins Amount actually available for use by the body When working with a client who has a vitamin deficiency -- important for healthcare provider to evaluate factors that may be affecting bioavailability: – – – – – Life-stage and nutrient status Changes to normal GI transit time Health conditions Food processing and preparation Sources of vitamin Vitamin Absorption Small intestine primary site – Doesn’t absorb 100%; typically increases when the body needs more Fat-soluble vitamins are chemically similar to lipids, and found in fatty portions of food – Fat digestion facilitates absorption (e.g., bile) – Adding small am’t fat to low-fat foods (e.g., salad dressing on raw vegetables; adding butter to steamed broccoli) can enhance absorption Fat vs. Water-Soluble Vitamins Difference in solubility affects the way our body absorbs, transports, and stores vitamins Fat-soluble: vitamin A, D, E, K Intestinal cells absorb fatsoluble vitamins (along with dietary fat), package them into lipoproteins --> release to lymph system --> liver --> stored/re-packaged for delivery to other tissues Excess accumulate in liver and fatty tissues (reserves can last for weeks or months) Water-soluble: B vitamins and vitamin C Intestinal cells absorb right into bloodstream Not stored in appreciable amounts, so needed regularly from diet Excess: kidneys can excrete in urine, so amount is regulated Vitamin Absorption Diseases that affect GI tract can reduce absorption and lead to deficiencies – E.g., cystic fibrosis – unable to digest fat properly (b/c blockages in ducts); often develop deficiencies of fat-soluble vitamins Some may benefit from taking large oral doses to enable small amounts of vitamins to be absorbed; in other cases injections may be needed Enrichment and Fortification Enrichment (add back vitamins that were taken our during refinement): helps protect from developing deficiency diseases associated with lack of thiamin, riboflavin, niacin, folate, iron – Doesn’t replace vit E, B6, magnesium, several other micronutrients, or fiber that were naturally present in unrefined grain Fortify (add vitamins that weren’t originally there): added particularly to flavored drinks otherwise considered sources of empty kcal – Some concerns re: consuming excessive amounts of a few vitamins while reducing intake of others Vitamin Toxicity More not necessarily better When cells saturated with a vitamin, they contain all they need and can’t accept additional amounts – Continuing to take vitamin can produce toxicity disorder (exposure to excess micronutrient or its by-products can damage cells) Liver damage can also occur as a result of the intake of toxic levels of some vitamins Most don’t need to be concerned unless they are taking megadoses in supplement form, or large amounts of fortified foods regularly – Read labels carefully and talk to healthcare providers – Taking supplement cannot make up for consuming a poor diet Vitamin Deficiency Vitamin deficiencies usually result from inadequate diets or conditions that increase body’s requirement for vitamins (e.g., reduced intestinal absorption) – Severe deficiencies uncommon in North America... but many consume less than recommended amounts of fatsoluble vitamins (A,D,E,K) – Vulnerable populations at risk for deficiencies: alcoholism, older adults, persons hospitalized for lengthy periods, ppl consuming very-low-fat and poorly planned vegan diets, eating disorder (anorexia nervosa), intestinal conditions that interfere with vitamin absorption, rare metabolic defects Water-Soluble Vitamins The B Vitamins (eight of them!) – Originally thought to be one single compound, but are actually many different compounds -- Thiamin (B1) -- Vitamin B6 -- Riboflavin (B2) -- Folate (B9) -- Niacin (B3) -- Vitamin B12 -- Pantothenic acid (B5) -- Biotin (B7) Vitamin C – Antioxidant, works with fat-soluble antioxidant vitamin E (E quenches free radical and becomes a free radical; C can stabilize it) Module 8 Learning Objectives 1. Introduce vitamins and describe the key features of water vs. fat-soluble vitamins 2. List the major physiological functions of each water-soluble vitamin Discuss DRIs and identify major food sources (& any interactions) Discuss major symptoms and diseases associated with deficiency and toxicity Water-Soluble Vitamins The B Vitamins (eight of them!) – Originally thought to be one single compound, but are actually many different compounds -- Thiamin (B1) -- Vitamin B6 -- Riboflavin (B2) -- Folate (B9) -- Niacin (B3) -- Vitamin B12 -- Pantothenic acid (B5) -- Biotin (B7) Vitamin C – Antioxidant, works with fat-soluble antioxidant vitamin E (E quenches free radical and becomes a free radical; C can stabilize it) Five B-Complex Vitamins Thiamin (B1) Pantothenic acid (B5) Riboflavin (B2) Biotin (B7) Niacin (B3) Thiamin (B1) Thiamin (B1) Functions Reme mbe to ma r! TPP ne e ke ac etyl C ded oA Part of coenzyme TPP – Necessary for breakdown of CHO [to release energy] – Participates in chemical reaction that removes CO2 molecule from larger compound Also needed for: – Synthesis of neurotransmitters (e.g., acetylcholine; needed for muscle contraction) Thiamin (B1) Thiamin needs related to energy requirements and CHO intake, therefore slightly higher for men vs. women Thiamin found in small amounts in many foods; if person’s diet supplies adequate energy – generally enough thiamin Thiamin (B1) Deficiency (Beriberi) First described in Chinese writings over 4000 y ago, but not widespread until 19th century when refined white rice became popular (removing bran removes thiamin) Very little thiamin stored in body – deficiency symptoms occur within a few days – Very week and poor muscular coordination (deficient acetylcholine production) Body systems with high energy needs deteriorate first (deficient glucose metabolism) – Digestive damage: diarrhea – Muscle damage: muscle wasting and pain – Nerve damage: disrupts coordination and causes “pins and needles” Thiamin (B1) Deficiency (Wernicke-Korsakoff Syndrome) Degenerative brain disorder associated with thiamin deficiency – Primarily alcohol-induced malnutrition b/c alcohol reduces thiamin absorption and increases its excretion Signs: abnormal eye movements, staggering gait, distorted thought process Resolves if eliminate alcohol and obtain thiamin injections – Without prompt treatment, permanent disability or death Riboflavin (B2) Riboflavin (B2) Functions Forms active coenzyme FAD – Glycolysis – CAC – ETC Important for break down of fatty acids Works as coenzyme during breakdown of some AA Important for rbc formation Involved directly or indirectly in converting folate, niacin, vitamin B6 and vitamin K into their active forms Riboflavin (B2) Milk is the best source of riboflavin in the Canadian diet Light can destroy it – Store in opaque packages; paper or plastic Riboflavin (B2) “The precise magnitude of loss varies with the duration and intensity of exposure. In a similar fashion, prolonged storage of milk in clear bottles can result in riboflavin degradation. Opaque plastic or cardboard containers provide modest protection of milk that is stored on a grocery shelf exposed to continuous fluorescent lighting. Thus, milk and milk products should be protected against UV and fluorescent lighting; otherwise significant amounts of riboflavin as well as vitamin A (retinol), which is also susceptible to UV light, will be lost, and food quality will deteriorate.” Riboflavin (B2) Riboflavin and light Best practice: store milk in opaque containers Organic milks marketed in glass – Because of perception? – Those interested in organic milks may also be conscious of plastic waste and food contamination – Glass is the only material that does not react with food contents Both riboflavin and vitamin A are sensitive to store lighting for prolonged periods Riboflavin (B2) Deficiency (ariboflavinosis) Overt deficiency rare (documented in industrialized and developing nations) – Most often accompanied by other nutrient deficiencies (i.e., vitamin B6 and niacin) Signs and symptoms: – Fatigue – Inflammation of mucous membranes that line mouth and throat – Glossitis (swollen and sore tongue) – Chapped lips – Cheilosis (scaling/cracking skin around corners of mouth) – Dermatitis (inflamm of skin) – Eye disorders Niacin (B3) Niacin (B3) Functions Forms active coenzymes NAD, NADP; involved in ~200 reactions, inclu: – Glycolysis – CAC – ETC Also needed to break down fatty acids and some AA Unique among B vitamins; body can synthesize it from AA tryptophan (but need other nutrients as well [iron, riboflavin, vitamin B6]) Niacin (B3) Precursor tryptophan supplies ~1/2 niacin intake RDA is expressed as niacin equivalents (NEs) – 1 NE = 1 mg of niacin or 60 mg of tryptophan – …60mg of tryptophan yields 1 mg niacin Niacin (B3) Deficiency (Pellagra) Ppl at risk: alcoholism, anorexia nervosa, rare disorders that disrupt tryptophan metabolism Early signs/symptoms: poor appetite, weight loss, weakness Later symptoms (pellagra) include 4 D’s: Dermatitis (“rough skin”), Diarrhea, Dementia, Death Since other nutrients (iron, riboflavin, vitamin B6) needed to convert tryptophan to niacin, deficiency in them contributes to damage Rare in developed nations; sometimes seen in alcoholism Niacin (B3) Toxicity DRI UL: 35mg/day from fortified foods, supplements, or medications No evidence of toxicity from dietary sources Megadoses of niacin may be prescribed to reduce LDLc and increase HDLc – Side effects: flushing of skin, tingling sensation in hands/feet, GI upset, nausea / vomiting, liver damage, high blood sugar levels, blurred vision – Using statin along with niacin [to treat elevated LDLc] not shown to reduce death from CVD April 2016 FDA withdrew approval of medications that combine niacin with statin Pantothenic Acid (B5) Pantothenic Acid (B5) Functions Component of CoA [required to make Acetyl CoA] – Important for breakdown of CHO, fatty acids, AA Pantothenic Acid (B5) Easily damaged: – freezing, canning will decrease content – processing and refining grains destroys ~40-75% – cooking destroys up to 50% in meat and up to 80% in vegetables Pantothenic Acid (B5) Deficiency Virtually nonexistent in general population – b/c wide distribution of PA in foods In research settings: irritability and restlessness, fatigue, digestive disturbance, sleep disturbance, numbness and tingling, muscle cramps, staggered gait, low blood glucose levels Biotin (B7) Biotin (B7) Functions In coenzyme form biotin participates in chemical reaction that adds CO2 to other compounds – Promotes synthesis of glucose and fatty acids – Breakdown of certain AA Essential for regenerating oxaloacetate in CAC cycle Biotin (B7) No RDA (difficult to estimate because some biotin is produced by bacteria in GI tract & absorbed) AI based on extrapolation from amount of biotin in human milk (most major nutrition surveys do not report biotin intake) Biotin (B7) Biotin (B7) Deficiency Signs of biotin deficiency conclusively demonstrated in individuals consuming raw egg whites over long periods of time, and in patients receiving total parenteral nutrition (TPN) solutions that do not contain biotin Symptoms: – Dermatitis (often appearing as red scaly rash around eyes, nose, mouth) – CNS abnormalities (depression, lethargy, hallucinations, paresthesia of extremities) Infants with biotin deficiency experience developmental delays Thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), and biotin (B7) are widespread in the food supply, and overt deficiencies are rare in North America. They are all incorporated into coenzymes that metabolize CHO, PRO, FAT. High doses of thiamin and riboflavin appear to be harmless, but megadoses of niacin should be taken only under medical supervision (no RDA, EAR, UL for pantothenic acid or biotin). Water-Soluble Vitamins The B Vitamins (eight of them!) – Originally thought to be one single compound, but are actually many different compounds -- Thiamin (B1) -- Vitamin B6 -- Riboflavin (B2) -- Folate (B9) -- Niacin (B3) -- Vitamin B12 -- Pantothenic acid (B5) -- Biotin (B7) Vitamin C – Antioxidant, works with fat-soluble antioxidant vitamin E (E quenches free radical and becomes a free radical; C can stabilize it) Vitamin B6, Folate (B9), Vitamin B12 Function in close cooperation with each other to help control: – Homocysteine levels – Support rbc synthesis Vitamin B6 Vitamin B6 Functions Family of 3 compounds: – Pyridoxine – Pyridoxal – Pridoxamine Convert vitamin forms to primary B6 coenzyme pyridoxal phosphate (PLP) 1. PLP facilitates reactions involved in amino acid metabolism (inclu. conversion tryptophan to niacin); transamination reactions that form nonessential amino acids Vitamin B6 Functions 2. PLP participates in production of heme (ironcontaining portion of hemoglobin – protein in rbc that transport O2) 3. PLP converts a potentially toxic amino acid homocysteine to cysteine (a nonessential amino acid) – Functions in close cooperation with vitamin B12 and folate; all 3 help control homocysteine levels Vitamin B6 Vitamin B6 Deficiency 1. AA trans and deamination Without adequate B6, all AA become essential Neurotransmitter synthesis affected – Depression, headaches, confusion, numbness and tingling in extremities, seizures Vitamin B6 Deficiency 2. Anemia – Low B6 causes deficiency in hemoglobin synthesis (protein inside red blood cells that carry O2) – Red blood cells are small (microcytic) and pale (hypochromic), O2 binding capacity is decreased Vitamin B6 Deficiency 3. Heart Disease Build up of homocysteine more prone to endothelial cell injury inflammation atherosclerosis Hyperhomocysteinemia correlated with occurrence of blood clots, heart attacks, strokes (CVD) Vitamin B6 breaks down homocysteine (by converting it to cysteine) Vitamin B6 DRI UL: 100mg/day from fortified foods and/or supplements Toxicity UL based on amount that will not cause nerve damage in the majority of healthy people Difficult to take in amounts for toxicity from food sources Unlike most B vitamins, megadoses of B6 are toxic (2-6g/day), causing severe sensory nerve damage (peripheral neuropathy) – Signs and symptoms: walking difficulties, numbness of hands and feet (nerve damage resolves when megadose is stopped) Folate (B9) Folate (B9) Named for its best natural source – green leafy vegetables (foliage) Before folate can be absorbed, all but one glutamate needs to be removed (by enzymes in brush boarder of small intestine) More glutamates = more work for your body to break down 1 DFE = 1 μg folate = 0.6 μg folic acid Found in supplements (100% bioavailable) Found in foods (50% bioavailable) Folate (B9) Folate (B9) Folate refers to group of related compounds that includes folic acid – Folic acid refers specifically to synthetic form of vitamin found in supplements (and added to fortified foods) Currently nutrient databases and nutrition labels do not express the folate content of food in DFEs, which take into account different bioavailabilities of folate sources Folate (B9) Folate (B9) Cells convert folate to group of folatecontaining coenzymes tetrahydrogolate (THF) – THF accepts single-carbon group (e.g., CH3) from one compound and transfers it to another … THF participates in many chemical reactions involved in DNA synthesis and amino acid metabolism – As cells prepare to divide, they need THF to make DNA Folate (B9) Functions 1. Essential for healthy embryotic development 2. THF needed to make DNA as cells divide (e.g., rbc) 3. THF can transfer CH3 group to vitamin B12, that then transfers CH3 group to homocysteine, forming methionine (this process recycles methionine) – When B12 is not available, folate can’t be used Folate (B9) Folate (B9) Deficiency Prevalence of low blood levels of folate declined since introduction of folic acid fortification [over 20y ago] – teeth are lost, bone pain, fractures, diarrhea, depression … death Mild scurvy more common: sore inflamed gums and fatigue Vitamin C Toxicity UL: 2000 mg/day Megadoses (>3000 mg/day): – Linked to GI discomfort, cramps, diarrhea – Antioxidant role can switch to prooxidant --> increases iron absorption, leads to generation of free radicals No evidence suggesting vit C is carcinogenic or teratogenic or that it causes adverse reproductive effects How are we doing? Preserving Vitamin Content of Foods Many fruits and veges are highly perishable – Should be eaten soon after harvested to ensure max vitamin retention Some vitamins (niacin, vitD), resist destruction by usual food storage conditions or prep methods; others (vitC, thiamin, folate) easily destroyed / lost by improper food storage or cooking methods – Fresh produce retains natural vitamin content better when stored at temp near freezing, high humidity, away from air (tomatoes, bananas, garlic should be stored at room temp) Preserving Vitamin Content of Foods Exposure to excessive heat, alkaline substances (e.g., baking soda), light, air can destroy certain vitamins (vitC) – Wait to trim, peel, cut raw fruits/veges until just before eating – Darker leaves generally contain more vitamins than paler inner leaves or stems Water-soluble vitamins can leach out of food and dissolve in cooking water (often discarded) – Reuse water for soups / sauces – Cutting into large pieces reduces amount surface area exposed to heat – Cook with skins on (and eat the skin!) Preserving Vitamin Content of Foods Cooking methods that involve little contact between produce and water (e.g., microwaving, steaming) can conserve some vitamins Sometimes fresh fruits and raw vegetables are better sources than canned / frozen versions – However, produces frozen immediately after being harvested and then properly stored can be just as nutritious as fresh Nutrients in Enriched Pasta Health Canada requires the enrichment of pasta with folic acid, niacin, thiamin, riboflavin, and iron All nutrients that are added to the product must be listed on the Nutrition Facts Table *whole grains are low in folate, but white flour and pasta are enriched with folic acids Supplements? Vegans / no dairy – Vegans: vitamin B12 fortified foods – No dairy: calcium & vitamin D Infants / children – Supplemental fluoride, vitamin D, iron (under certain circumstances) Pregnant women / women of childbearing age – Folic acid, iron, multivitamin/mineral supplements Older adults – B12 supplements or fortified foods (due to high incidence of atrophic gastritis) – Vitamin D Individuals with dark pigmentation – May not synthesize enough vitamin D Individuals with restricted diets – Vitamin/mineral supplements People taking medications – May interfere with absorption/use of some nutrients Cigarette smokers / alcohol users – Smokers: Vitamin C – Alcohol: B vitamins END Water Soluble Vitamins! Next: Fat Soluble Vitamins