NUTR 1004 Lecture 9 Vitamins PDF

1 Vitamins Kemar Bundy MSc., MPH, PhD(c) NUT 1004 University of Technology, Jamaica  Learning Outcomes Classify vitamins according to whether they are fat soluble or water soluble. Discuss ways to conserve the vitamin content of foods or increase vitamin...

1 Vitamins Kemar Bundy MSc., MPH, PhD(c) NUT 1004 University of Technology, Jamaica  Learning Outcomes Classify vitamins according to whether they are fat soluble or water soluble. Discuss ways to conserve the vitamin content of foods or increase vitamin bioavailability. Explain the function of an antioxidant and define enrichment and fortification. List the four fat-soluble vitamins and identify good dietary sources of each fat-soluble vitamin (or provitamin). Discuss major functions of each fat-soluble vitamin. Identify health problems associated with excesses and deficiencies of fat- soluble vitamins. ©McGraw-Hill Education  Learning Outcomes Identify health problems associated with excesses and deficiencies of vitamin E and vitamin K. List the water-soluble vitamins and identify good dietary sources of each vitamin (or its precursor). Discuss major functions of each water-soluble vitamin. Identify health problems associated with excesses and deficiencies of water-soluble vitamins.  Learning Outcomes Identify health problems associated with excesses and deficiencies of vitamin B12, vitamin C, pantothenic acid, and biotin. List the water-soluble vitamins and identify good dietary sources of each vitamin (or its precursor). Discuss major functions of each water-soluble vitamin. Evaluate the use of vitamin supplements with respect to their potential health benefits and hazards. Identify foods that may increase risk of cancer. Discuss some practical steps that people can take to reduce their risk of cancer. ©McGraw-Hill Education Vitamins: Basic Concepts 2 What is a vitamin? A complex organic compound that: Is not made by the body — or made in amounts that are enough to maintain good health Occurs naturally in common foods Causes a deficiency disorder when it is missing from the diet Restores good health, if the deficiency disorder is treated early by supplying the missing substance ©McGraw-Hill Education What are Major Roles of Vitamins? Vitamins may: Have hormonal action (e.g., vitamin D) Participate in certain chemical reactions (e.g., anti-oxidation) Vitamins do not provide energy Regulate a variety of body processes Cell division and development Growth and maintenance of tissues Vitamins do not provide energy, although many participate in the process that releases energy from macronutrients (see Figure 8.2). ©McGraw-Hill Education  Radical Formation and Viatmins Oxidation reactions can form radicals (or “free radicals”), substances with an unpaired electron. Oxidation reactions involve loss of electrons. Most free radicals are highly reactive (unstable), because they have an unpaired electron. A free radical can removean electron from a more stable molecule, such as DNA, a protein, or a polyunsaturated fatty acid Free radical damage may contribute to serious chronic diseases and premature aging. Vitamins (e.g., Vit E, Vit C) exert anti-oxidation effect. ©McGraw-Hill Education Radical Formation: Damages Components of Cells ©McGraw-Hill Education How Do Antioxidants Work? An antioxidant gives up an electron to stabilize a radical. By giving up the electron, an antioxidant stabilizes the radical, protecting other molecules. Antioxidants ©McGraw-Hill Education Free Radicals and Antioxidants Removes electrons Donates electrons ©McGraw-Hill Education  What are Sources of Vitamins Vitamins occur naturally in foods or they are synthesized in a lab (vitamin supplements). Biological activity—vitamin’s effects in the body - Some vitamins are more biologically active in the natural form (for example, vitamin E) - Others are more active in the synthetic form (for example, folic acid). Bacteria in the large intestine can produce certain vitamins (biotin and vitamin K) that can be absorbed to some extent. The body is able to synthesize vitamin D and niacin under certain conditions. ©McGraw-Hill Education 10 How are Vitamins Classified? Fat soluble - A, D, E, & K Associated with lipids in foods and the body Do not dissolve in water or urine Stored in the body and may be toxic Water soluble - B vitamins & C Dissolve in watery components of foods and the body Excreted in urine Most are not stored to a major extent Generally non-toxic ©McGraw-Hill Education Vitamin Enrichment and Fortificatio Raw foods can lose nutrients during processing, which includes refinement. Grain enrichment o Addition of specific amounts of thiamin, riboflavin, niacin, folic acid, and the mineral iron to refined flour & milled grains o Grain enrichment program does not restore all of the nutrient’s that grain loses during refining. Fortification o Addition of any nutrient to a wide array of commonly eaten processed foods, during their manufacturing. ©McGraw-Hill Education  Vitamin Absorption Most vitamins are absorbed in the small intestine. Absorption generally increases when the body needs more of the vitamin: Growth (e.g., during infancy and adolescence) Pregnancy Lactation (milk production) Fat-soluble vitamins are absorbed with dietary fat. Diseases that affect the GI tract can reduce vitamin absorption. Cystic fibrosis (CF) interferes with fat digestion and fat-soluble vitamin absorption. ©McGraw-Hill Education  Vitamin Deficiency and Toxicity Disorders Deficiencies can result from poor diets or certain health conditions. In the U.S., severe deficiencies are uncommon because of: Food preservation practices Food enrichment and fortification Widespread availability of fruits and vegetables Many Americans do not consume recommended amounts of E, D, and choline. ©McGraw-Hill Education Populations at Risk for Vitamin Deficiency Alcoholics Older adults Hospitalized people (long-term care) People with o Anorexia nervosa o Certain gastrointestinal disorders o Rare metabolic conditions ©McGraw-Hill Education Maximizing Vitamin Contents of Food Vitamin C, thiamin, and folate are easily destroyed by improper storage and preparation practices Niacin and vitamin D tend to be very stable. Tips to preserve vitamins in foods: Avoid buying wilted, bruised, or shriveled produce. Cook in small amounts of water. Avoid cutting foods that will be cooked into small pieces. Use quick cooking methods such as microwaving, steaming, and stir-frying. Freeze produce to preserve vitamins. ©McGraw-Hill Education MyPlate: Fat-Soluble Vitamins ©McGraw-Hill Education ©McGraw-Hill Education 18  Vitamin A Animal sources: Retinol (preformed vitamin A): Most active form Liver and fish liver oils Plant sources: Primarily Beta-carotene (provitamin A) Some carotenoids, particularly beta-carotene, can be converted to active vitamin A Yellow-orange and green fruits and vegetables See Table 8.3 for some food sources. Major Normal vision, reproduction, and cellular growth functions: Immune system activity Epithelial cell production, maturation, and maintenance ©McGraw-Hill Education  Vitamin A ©McGraw-Hill Education What Is Night Blindness? The inability to see in dim light Early sign of vitamin A deficiency The retina contains rods and cones, specialized nerve cells essential for vision. Rods and cones need vitamin A to function properly. See Figure 8.8 ©McGraw-Hill Education  Vitamin A Deficiency Deficiency Night blindness is an early sign. Certain epithelial cells produce too much keratin. Keratin - tough protein found in hair, nails, and outermost layers of skin Excess keratin: skin becomes rough and bumpy Inner eyelid has cells that normally secrete mucus to protect cornea. When these cells become keratinized: Xerophthalmia (“dry eye”) results. Can lead to blindness ©McGraw-Hill Education  Vitamin A Toxicity Excess vitamin A may lead to liver damage. Teratogen: Causes birth defects Liver and fish liver oils are rich sources of preformed vitamin A. Excess beta-carotene (carotenemia): Yellowing of skin due to excessive beta-carotene intake Generally harmless May occur in infants who eat too much orange/yellow or dark green baby foods. Skin color returns to normal when such foods are not eaten. ©McGraw-Hill Education Vitamin D: Basic Actions and Functin Vitamin D is needed for: Increasing calcium & phosphate deposits in bone Reducing urinary calcium excretion Increasing calcium & phosphate absorption ©McGraw-Hill Education Vitamin D Synthesis 1,25-(OH)2 Vitamin D3 ©McGraw-Hill Education Maintaining Normal Blood Calcium Levels ©McGraw-Hill Education Vitamin D: Sunlight and Foods People who are most likely to synthesize adequate prohormone D live south of the 33rd parallel and are outdoors when sunlight is most intense. Foods: Fatty fish Fish liver oils Fortified milk ©McGraw-Hill Education  Vitamin D ©McGraw-Hill Education  Vitamin D: Deficiency and Toxicity Deficiency Rickets Uncommon in Jamaica. Fluid milk is often fortified with D. At risk: breastfed infants who have dark skins and are not exposed to sun, the elderly due to physiological and exposure changes Osteomalacia — “adult rickets” Women who lack sun exposure Impaired immune system function Vitamin D is a nutrient of public health concern Excess vitamin D from foods (not sun exposure) can be toxic Calcium deposits in soft tissues, resulting in cell death ©McGraw-Hill Education  Vitamin D Rickets: vitamin D deficiency in children Results in soft bones that do not grow properly and become deformed Figure 8.11 ©McGraw-Hill Education  Vitamin D Toxicities Does not occur from sunlight or Supplementation dietary sources Excess blood calcium. Deposits of calcium in kidneys, heart, and lungs Anorexia. Upper Limit: Nausea and vomiting. 4000 IU Weakness. Joint pain. Kidney dysfunction Vitamin D: 1 IU = 0.025 mcg ©McGraw-Hill Education Vitamin E: Antioxidant Function ©McGraw-Hill Education  Vitamin E ©McGraw-Hill Education Vitamin E: Deficiency and Toxicity Seeds, nuts, and plant oils are rich sources. See Table 8.5. Deficiency Impaired immune system function Nerve damage Loss of neuromuscular control Blindness Toxicity Excess may interfere with vitamin K’s role in blood clotting Sign: Uncontrollable bleeding ©McGraw-Hill Education Vitamin K Function : Blood Clotting ©McGraw-Hill Education  Vitamin K Rich food sources: Green leafy vegetables ©McGraw-Hill Education Vitamin K: Deficiency and Toxicity Deficiency May occur in newborns; people with impaired absorption or liver function, or people who are on long-term antibiotic therapy Vitamin K injection is routinely given to newborns. Toxicity None known for natural forms Synthetic forms are toxic ©McGraw-Hill Education Water-Soluble Vitamins Most function as components of specific coenzymes. Many enzymes require coenzymes to function. Coenzymes: small molecules that regulate chemical reactions by interacting with enzymes Once activated, the enzyme- coenzyme complex enables the reaction to occur. ©McGraw-Hill Education MyPlate: Water-Soluble Vitamins ©McGraw-Hill Education  Thiamin (B1) Functions Part of coenzyme involved in release of energy from carbohydrates Metabolism of certain amino acids Synthesis of neurotransmitters Deficiency disease: Beriberi Wernicke-Korsakoff syndrome: Typically seen in alcoholics ©McGraw-Hill Education  Vitamin B1 ©McGraw-Hill Education  Riboflavin (B2) Function Coenzyme for metabolism of carbohydrate, lipids, and amino acids Dairy foods, liver, and enriched grains are major food sources. Deficiency: Rarely occurs ©McGraw-Hill Education  Niacin (B3) Functions Part of two coenzymes Needed to obtain energy from macronutrients Pellagra: the “4 D’s” of pellagra Deficiency Dermatitis Diarrhea Dementia Death Toxic amounts (mega-doses) can cause GI ulcers, vision loss, & liver damage. ©McGraw-Hill Education  Vitamin B3 ©McGraw-Hill Education  Vitamin B-6 Function Part of coenzyme needed for amino acid metabolism Rarely occurs, but signs and symptoms include: Deficiency Dermatitis, anemia, convulsions, depression, and confusion Toxic (mega-doses) : Nerve damage ©McGraw-Hill Education  Folate Folic acid (synthetic); folate (natural) Functions Part of coenzyme tetrahydrofolic acid (THFA) THFA involved in DNA and amino acid metabolism Conversion of homocysteine to methionine Major role relates to vitamin B-12. See Figure 8.22. Food sources of folate include: Leafy green vegetables, liver, legumes, asparagus, broccoli, and oranges ©McGraw-Hill Education  Folate ©McGraw-Hill Education  Folate Deficiency Early deficiency: Lack of folate affects cells, such as red blood cells (RBC), that rapidly divide. Mature RBCs do not have nuclei and live approximately 4 months. - Without folate, RBC precursor cells enlarge, but cannot divide. Bone marrow releases some large, immature, abnormal RBCs with nuclei (megaloblasts) into the bloodstream causing a type of anemia. ©McGraw-Hill Education Folate Deficiency: Neural Tube Defec During the first few weeks after conception, the neural tube forms. Neural tube develops into the brain and spinal cord. Folate-deficient pregnant women are at risk of giving birth to infants with neural tube defects. Spina bifida Anencephaly ©McGraw-Hill Education  Vitamin B-12 Functions Part of coenzymes needed for: Folate metabolism Maintenance of myelin sheaths Absorption B-12 in foodof is dietary bound toB-12: proteins In stomach, HCL and pepsin are required to release B-12 from proteins After release from protein, B-12 must bind to intrinsic factor for absorption in ileum. ©McGraw-Hill Education Vitamin B-12 Deficiency Disorders Food-cobalamin malabsorption: Common in older adults due to declining gastric acid production. Can also occur: In people with alcoholism After gastric bypass surgeries When taking certain medications (e.g., stomach acid reducers) Pernicious anemia: Genetic defect reduces production of intrinsic factor Megaloblastic anemia Nerve damage Confusion Difficulty walking and maintaining balance Death ©McGraw-Hill Education  Vitamin B12 ©McGraw-Hill Education  Pantothenic Acid and Biotin Pantothenic acid (B5): Component of coenzyme A, which is critica for energy metabolism and fatty acid production in the body. Pantothenic acid is so widespread in foods that a nutritional deficiency is unlikely to occur among healthy people who eat varied diets. People who abuse alcohol may develop pantothenic acid and other B-vitamin deficiencies. Biotin (B7) Biotin participates in chemical reactions that add carbon dioxide to other compounds. It promotes the synthesis of glucose and fatty acids and the breakdown of certain amino acids. Severe deficiencies of biotin rarely occur because intestinal bacteria produce some biotin. ©McGraw-Hill Education  Vitamin C: Functions Functions — not part of a coenzyme, but needed for: Collagen synthesis (see Figure 8.28.) Protein that gives strength to connective tissues Antioxidant activity Other major roles Immune system functioning Synthesis of bile, certain neurotransmitters, and hormones ©McGraw-Hill Education  Vitamin C ©McGraw-Hill Education Vitamin C: Deficiency and Toxicity In general, fruits and vegetables are rich sources of vitamin C. Deficiency is called scurvy. Very rare in U.S., because about 10 mg/day prevents scurvy. Signs & symptoms: poor wound healing, pinpoint hemorrhages, bleeding gums, bruises, and depression Can result in death Toxicity Kidneys excrete excess amounts of the vitamin & oxalate, a by-product of vitamin C metabolism. Increases risk of oxalate kidney stones, particularly in susceptible persons ©McGraw-Hill Education  Choline Humans require choline, especially during prenatal (before birth) development. Choline is considered to be a vitamin-like nutrient. The body can make choline, but under certain conditions, the body does not synthesize enough to meet its needs. ©McGraw-Hill Education  Niacin as Medicine? Uses: High doses can lower LDL cholesterol and raise HDL cholesterol Flushing Side effects: of skin on face and chest, itchy skin, GI tract upset, and liver damage Megadoses are very toxic, so a qualified medical practitioner (e.g., physician) should be consulted before using. ©McGraw-Hill Education  Vitamin B-6 as Medicine? Uses: Claims include help for symptoms of premenstrual syndrome (PMS) Researchers continue to explore possible value of B-6 as a treatment for PMS. Side effects of high doses: Severe sensory nerve damage Walking difficulties Numbness of hands and feet Nerve damages generally resolves when vitamin intake is reduced to normal levels. ©McGraw-Hill Education Folic Acid, B-6, and B-12 as Medicine Use: Lowers blood homocysteine levels when taken together (folic acid, B-12, and B-6). CVD: Recent studies of subjects with CVD suggest folic acid supplements do not reduce risk of having another heart attack. Alzheimer’s disease: No scientific evidence to support taking B-6 along with other vitamins to slow or prevent cognitive decline among older adults. ©McGraw-Hill Education  Vitamin C as Medicine? Uses: Does not prevent common cold but may reduce duration and severity of the infection Reduces oxidation of LDL cholesterol Research provides inconsistent (mixed) results. More research needed to determine whether high doses help reduce CVD risk. Eating more fruits and vegetables may reduce risk of cancer. Taking vitamin C supplements generally does not show the same benefits. More research is needed to determine whether vitamin C helps reduce cancer risk or aids in cancer treatment. ©McGraw-Hill Education  Vitamin E as Medicine? Questionable benefits: Recent studies do not support taking vitamin E (alpha-tocopherol) supplements to reduce risk of cardiovascular disease, cancer, and/or Alzheimer’s disease. May increase risk of prostate cancer (men) and hemorrhagic stroke Future studies using other forms of vitamin E may provide scientific support for taking the vitamin to prevent or treat certain chronic diseases. ©McGraw-Hill Education  Carotenoids as Medicine? Diets rich in fruits and vegetables are associated with lower risk of certain cancers, CVD, and age-related macular degeneration (AMD). Dietary supplements containing beta-carotene fail to show benefits for cancer and AMD risks. Lutein and zeaxanthin (carotenoids) may help slow progression of AMD. Dietary supplements with beta-carotene may be harmful, especially among smokers. Reasonable advice: Consume vitamins in their natural state (in foods) rather than in dietary supplements. ©McGraw-Hill Education  What Is Cancer? A group of chronic diseases characterized by cells that have mutated (have damaged genes). Cancerous (malignant) cells are “out of control” and can spread (metastasize). A mass of cancerous cells results in a malignant tumor. Carcinogens: environmental factors that trigger cancers. ©McGraw-Hill Education  Major Risk Factors Aging (most occur in people over 50 years of age) Family history Tobacco use Radiation exposure Certain environmental exposures (irritants) Certain bacterial or viral infections Elevated levels of certain hormones Consumption of alcohol and certain foods (see Table 8.15) Excessive body fat and physical inactivity ©McGraw-Hill Education  https://commons.wikimedia.org/wiki/File:Charcoal_Steak https://www.ultimatehlth.com/blog/processed-meats-cancer-conne ©McGraw-Hill Education 19  Reducing the Risk Limit alcohol consumption. Achieve and maintain a healthy weight. Adopt a physically active lifestyle. Eat a healthy diet that limits red and processed meat intakes. Eat a healthy diet that emphasizes plant foods. Avoid certain environmental exposures related to carcinogens. ©McGraw-Hill Education Thank you ! ©McGraw-Hill Education