Transcript Carotene
Chapter 3 The Micronutrients of Balanced Meals: Vitamins, Minerals, Phytochemicals, and Water Dietary Reference Intake (DRI) Replaced U.S. Recommended Dietary Allowance (RDA) and Canadian Recommended Nutrient Intake (RNI) Includes four measures: Estimated average requirements (EAR)—amount of a nutrient estimated to meet needs of 50% of individuals RDA—average daily intake to meet ≥ 97% of needs of a healthy population Adequate intake (AI)—amount based on observation when RDA cannot be determined Tolerable upper intake level (UL)—highest level of intake with low risk of adverse effects Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 2 Dietary Reference Intakes Dietary reference intakes. This figure shows that the estimated average requirement (EAR) is the intake at which the risk of inadequacy to an individual is 50%. The recommended dietary allowance (RDA) is the intake at which the risk of inadequacy is very small (2% to 3%). The adequate intake (AI) does not bear a consistent relationship to the EAR or the RDA because it is set without being able to estimate the average requirement. It is assumed the AI is above what the RDA would be if it could be calculated. At intakes between the RDA and the tolerable upper intake level (UL), the risks of inadequacy and excess are both close to 0. At intakes above the UL the risk of adverse effects increases. Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 3 Plants Produce Vitamins Through Their Genetic Makeup Vitamins are organic and can be broken down Vitamins are grouped based on their ability to dissolve in fat or water Fat-soluble vitamins—A, D, E, K (stored in the body; require dietary fat intake for absorption) Water-soluble vitamins—Bs, C (not stored in the body; needed on a daily basis) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 4 Medical Causes of Vitamin Deficiency Fat-soluble vitamins (A, D, E, K) Fat-malabsorption due to: • Cystic fibrosis • Surgical removal of the ileum (lowest portion of the small intestine) • Medications/fat substitutes (Olestra) that inhibit absorption of fat Water-soluble vitamins (B vitamins, vitamin C) Medications such as proton pump inhibitors and anti-epileptic medications Excess urination due to diuretic treatment or excess fluid intake Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 5 Vitamin A and Beta Carotene Two types of vitamin A: Precursor—carotene (deep orange color as found in carrots, sweet potatoes, cantaloupe; also found in dark green, leafy vegetables); the liver uses the precursor form to make vitamin A Oranges are the exception to the color rule Preformed—retinol/retinol palmitate (liver, supplements); also found in water-soluble forms (the most toxic form typically used in food fortification) Carotene—harmless but can turn skin to orange color; avoidance of carotene allows return to normal color Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 6 Functions of Vitamin A Vitamin A is needed for: Retinal health and night vision Promoting good immunity Maintaining skin health (epithelial tissue) Promoting bone growth Reproduction Preventing a form of iron deficiency (Kelleher and Lonnerdal, 2005) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 7 Vitamin A Content of Foods in IUs; DRI: 900 mcg/day (2970 IUs) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 8 Vitamin D: “Sunshine Vitamin” Dietary intake is either from fortified foods (milk) or as naturally found in fish liver (cod liver oil or whole fish [with liver]) Cod liver oil advised by doctors to prevent rickets in children in the early 20th century Sun allows conversion in the skin of cholesterol into vitamin D Melanin interferes with sun’s ability to produce vitamin D Compromise message of sun exposure to prevent skin cancer while meeting vitamin D needs 20 minutes of sun exposure without sunscreen lotion Latitudes north of Philadelphia: the sun is too weak to make vitamin D in the skin from September through March Increased intakes of at least 800 IU advised in Northern climates; may be as many as 2000 IU needed Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 9 Functions of Vitamin D Allows calcium absorption for strong bones and teeth and allows the body’s use of calcium Needed for a strong and healthy immune system Helps prevent autoimmune diseases (type 1 diabetes, multiple sclerosis [MS]—Olympic skiers have the highest rate of MS) May help prevent “winter blues,” or seasonal affective disorder (SAD) Helps regulate blood pressure and acts as a tumor suppressant to help prevent cancer Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 10 Vitamin E: Tocopherol Originally discovered as necessary for rat reproduction Appears necessary for fetal growth An antioxidant vitamin—helps prevent cellular damage caused by oxidation Helps regulate cell signaling and gene expression Sources—nuts and peanut butter, vegetable oils, wheat germ Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 11 FYI Vitamin E during pregnancy may reduce risk of childhood asthma (Seaton, 2008) Vitamin E inadequacy during pregnancy may be linked with low birth-weight and smaller head circumference (Masters et al., 2007) Excess or deficiency of vitamin E appears linked to inflammation (Wagner et al., 2008; Gianello et al., 2007) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 12 Vitamin E Content of Common Food Sources Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 13 Vitamin K: Phylloquinone Allows for clotting of blood Involved in vascular function and bone metabolism Evidence it supports bone growth Found in green leafy vegetables, green tea, cauliflower, butter, soybean oil, legumes Intestinal bacteria produce vitamin K Only concern is usually related to Coumadin (an anticlotting medication), which necessitates stable intake of vitamin K; antibiotics used to treat gram-negative bacteria can cause vitamin K deficiency, with potential for increased effect of Coumadin Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 14 Deficiency Concerns of Vitamin K Newborn infants generally require injection at birth because of lack of intestinal bacteria Intracranial hemorrhage (ICH) at 1 to 2 months of age; signs and symptoms: vomiting, absence of pupil reaction, fontanel bulging, convulsions, irritability with coma Vitamin K supplement needed for infants with antibiotic treatment, diarrhea, liver problems, or breastfeeding With long-term use of antibiotics for gramnegative bacteria for children and adults, supplementation is advised Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 15 Water-Soluble Vitamins Water-soluble vitamins B vitamins B1: thiamin B8: biotin* B2: riboflavin B9: folate* B3: niacin B12: cobalamin B5: pantothenic acid* choline B6: pyridoxine and related substances *not generally referred to numerically Vitamin C (ascorbic acid) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 16 B Vitamins Easily destroyed with cooking Serve as cofactors to allow cellular metabolism; needed for energy production in the mitochondria Most B vitamins found in whole grains and legumes B2 found mainly in milk, eggs, peanuts, organ meats B3 requirement met, in part, by production from the amino acid tryptophan B12 found in animal products only Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 17 Folate: Names for “Foliage” May be referred to as vitamin B9 Named for a chief source of folate: foliage or dark-green, leafy vegetables Active form: folic acid, formed with vitamin C Aids in metabolism of DNA, promotes chromosomal health, red blood cell formation Helps prevent spina bifida if consumed in first few days after conception Women of childbearing years advised to consume 400 mcg folate daily Processed white-grain products are fortified with folate to lower the risk of infants born with spina bifida (a form of neural tube defect) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 18 Vitamin B12: Cobalamin Important in DNA synthesis and may affect bone formation (Tucker et al., 2005) Found in animal-based foods only; contains the mineral cobalt (hence the name cobalamin) Intrinsic factor needed to absorb B12 Deficiency causes irreversible nerve damage, megaloblastic anemia Vitamin B12 supplementation may not be adequate; intramuscular B12 injections commonly provided for the elder population (decreased intrinsic factor production) or persons with malabsorption (e.g., after gastric bypass surgery) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 19 Vitamin C (Ascorbic Acid): WaterSoluble Derivative of Glucose First vitamin identified from experience of “limeys” (British sailors)—scurvy avoided by eating lemons (then called limes) Scurvy = severe deficiency; mild deficiency related to bleeding gums and/or loose teeth, easy bruising, pedal edema, arthralgias (joint pain), and joint swelling Acts as “glue” to hold body cells together Promotes immunity and wound healing Promotes bone growth, collagen, and growth of all body tissues Serves as an antioxidant to reduce levels of free radicals (reactive oxygen species) for reduced risk of cellular damage Found in fruits and vegetables only (e.g., leafy greens, citrus, melons, potato, green peppers, berries, tomatoes) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 20 Class Review Time Can you list the four fat-soluble vitamins? Can you name at least two functions of each? Can you name the B vitamins? What are the 2 main roles of all B vitamins? What is another name for vitamin C? Which two food groups are the only sources of vitamin C? Can you name two signs of vitamin C deficiency? Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 21 Food Review Can you name three examples of carotene-rich foods? What is a food source of preformed vitamin A? Can you name at least one food example for each of the other three fat-soluble vitamins? What are the main food sources of Vitamin B2? What are the main food sources of Vitamin B12? Main food sources of folate Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 22 General Functions of Minerals Serve as building materials and found in all body constituents Bone and teeth (calcium, phosphorus) Hair, nails, and skin (sulfur) Blood (iron in hemoglobin) Serve as regulators of body metabolism Muscle contraction and relaxation (calcium, potassium) Blood clotting (calcium) Coenzymes (zinc, magnesium, potassium) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 23 Calcium Chief mineral in bones and teeth Allows for muscle contraction and function of nervous system and blood coagulation Found in high amounts in milk, soybeans, bones (i.e., bones of salmon/anchovies), some leafy greens: collards, seaweed, hard water Chief age for bone mineralization <35 years Osteoporosis risk factors—low calcium and/or vitamin D intake, Caucasian or Asian heritage, low body weight, rheumatoid arthritis, steroids, smokers, alcohol abusers and alcoholics Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 24 Calcium Foods; DRI 1000 mg Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 25 Magnesium: Part of the Chlorophyll Molecule Involved in strong bone formation Critical to 300 metabolic enzymes Regulates heartbeat, helps transport potassium and calcium, helps with muscle contractions, lowers inflammation Involved in energy metabolism Can serve as a calcium channel blocker (used to control hypertension and migraines) Bound with chlorophyll (green leafy vegetables) and also found in milk, legumes, fish, eggs Can be lost with diuretics and excess urination (as found with uncontrolled diabetes) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 26 Deficiency/Excess Magnesium Deficiency is rare based on serum values, but it is relatively common to have suppressed levels intracellularly Deficiency related to hypertension, ischemic heart disease, arrhythmia, preeclampsia of pregnancy, constipation, migraines, asthma, ventricular tachycardia Toxicity most likely with renal failure or excess intake of laxatives and antacids Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 27 Magnesium; DRI 350 mg Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 28 Phosphorus Helps enzymes act in energy metabolism Only second to calcium in body content Primarily found in bones A ratio of 1.5 calcium to 1.0 phosphorus intake advised in early infancy to prevent tetany Widely found in foods; added to carbonated beverages Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 29 Potassium Promotes regular heartbeat; altered levels contribute to irregular heart beat A key “electrolyte” (related to electric flow) Involved in blood pressure regulation – helps balance sodium intake High amounts in green leafy vegetables, whole grains, milk, citrus fruits, bananas, potatoes, tomatoes, melon, beets Excess avoided with kidney disease or use of ACE inhibitor Rx (avoid potassium chloride [KCl] in salt substitutes) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 30 Sodium Serves as an essential electrolyte Found in salt as sodium chloride (Na+Cl-), minor amounts found in leafy green vegetables, milk, eggs, meat; very low amounts in fruits and unprocessed grains 1 teaspoon salt contains 2400 mg Na+ The DASH diet (Dietary Approaches to Stop Hypertension) advocates restriction of 1500 mg Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 31 Trace Minerals Iron, Copper, Cobalt, Molybdenum, Zinc, Iodine, Selenium, Cobalt, Sulfur, Cadmium, Nickel, Tin, Vanadium, Silicon Found in trace amounts in the body Excess intake of trace minerals can be toxic Any supplemental intake of minerals needs to be a maximum of 100%-200% DRI in order to prevent toxicity Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 32 Fluorine Found in fluoride tablets and fluoridated water as used to promote strong teeth formation in children Also found in fish, tea, and gelatin Can be toxic and lead to mottling of teeth Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 33 Iodine Found in thyroid hormones and involved in general metabolism Has an antioxidant function Sea fish and seaweed naturally high in iodine; iodized salt is an important alternative source Deficiency states: hypothyroidism, goiter (see slide)—linked with reduced IQ, and cretinism, a form of mental retardation, of infants born to women with iodine deficiency (now rare because of iodized salt use) Excess intake leads to hyperthyroidism Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 34 Goiter: Caused By Iodine Deficiency Goiter. (From Swartz MH: Textbook of physical diagnosis: history and examination, ed 5, Philadelphia, 2006, Saunders.) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 35 Iron Carries oxygen in red blood cells Prevents iron-deficiency anemia Heme—animal sources: especially liver, meat and fish; heme form readily absorbed Nonheme—plant form such as beans, soy, dark leafy greans, fortified cereals, blackstrap molasses; need vitamin C source to convert to heme form for enhanced absorption Iron frying pans are a source of iron, with long duration of cooking and acidic foods leading to highest iron absorption Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 36 Phytochemicals: “Chemicals of Life” Vitamin-like substances recognized since the 1990s Includes lutein (found in green leafy vegetables) Lutein: essential to prevent macular degeneration Includes lycopene (found in tomatoes) Lycopene controls prostate tumors Estimated 100 phytochemicals yet to be identified Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 37 Food Preparation Strategies to Preserve Vitamin and Mineral Content Store fresh produce to avoid wilting and/or drying out Cook foods in whole pieces, as possible, to decrease surface area for leaching of minerals into cooking water Steam or microwave to reduce leaching of minerals Cover open containers of juice to preserve vitamin C Avoid excessive stirring while cooking to minimize exposure of vitamin C to air Keep milk out of light to preserve vitamin B2 content Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 38 Fortification Versus Enrichment Fortify—make stronger (e.g., iron-fortified cereal) Enrich—replace after removal by processing (e.g., enriched white bread with vitamins B1, B2, B3) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 39 Dietary Supplement and Health Education Act of 1995 (DSHEA) Restricted regulation authority of the FDA as supplements were distinguished from drugs and food additives If there are no claims of potency or no USP on the label, the quantity listed on the supplement label does not legally have to match the actual contents of the supplement Supplements are usually safe at 100% to 200% recommended daily allowance if “USP” is on the label or if product has been chemically analyzed (call toll-free number to inquire, if not stated) Supplements may contain contaminants, such as lead found with many calcium supplements; use name-brand product or look for “purity assured” labeling Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 40 Herbal Products Considered dietary supplements because of DSHEA, with same labeling issues Added issue of inadequate standardization of herbal products with active compounds in variable amounts, depending on growing conditions: light, moisture, temperature, soil conditions Can contain strong biologic compounds (alkaloids) that may be harmful (e.g., black cohosh may be found as form of “snakeroot”) (killed President Lincoln’s mother after she drank milk from a cow that had ingested this weed) Can have additive effects with prescribed medications (e.g., ginkgo biloba inhibits blood clotting and may have to be discontinued when anticlotting medications used with surgery) Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 41 Study Guide Vocabulary Estimated Average Requirement (EAR) Recommended Daily Allowance (RDA) Tolerable Upper Limit Dietary Reference Intake (DRI) Fat soluble vitamins Water soluble vitamins Carotene Retinol Ascorbic acid Scurvy Heme iron Non-heme iron Goiter Fortified Enriched Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 42 Study Guide (continued) Main functions of vitamin A, D, E, K, C, Calcium, phosphorous, potassium, sodium, magnesium, flouride, iodine (as discussed in class) 2 main functions of B vitamins Where/how do we acquire vitamin D? Which B vitamin is found only in animal products? Which B vitamin prevents neural tube defects? Which two food groups are sources of vitamin C? Which vitamin interacts with Coumadin? What vitamin increases non-heme iron absorption? Name the electrolytes. What do electrolytes do? Elsevier items and derived items © 2010, 2007 by Saunders, an imprint of Elsevier Inc. 43