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Nutrition and food constituents

Nutrition: it is the dynamic processes by which the body can utilize the consumed food for energy production, growth, tissue maintenance and regulation of body functions.

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Nutrition and food constituents

  1. 1. Dr. Dalia El-Shafei Assoc. prof., Community Medicine Department, Zagazig University
  2. 2. LEARNING OBJECTIVES: Identify sources, functions, effect of deficiency of nutrients. Understand the characteristics of adequate, balanced diet. Develop a diet plan by using the dietary guides and nutritional pyramid. Describe diets for vulnerable groups. Understand the causes, manifestations and control of malnutrition problems. Explain methods of assessment of nutritional status. Describe diet plans for selected chronic diseases (therapeutic diet).
  3. 3. Nutrition • The dynamic processes by which the body can utilize the consumed food for energy production, growth, tissue maintenance and regulation of body functions. A nutrient • A chemical substance that is present in food & needed by the body in amounts of g. as macronutrients (carbohydrates, proteins, fats) or mg. or µg. as micronutrients (vitamins, minerals) for energy production, growth and regulation of body functions. Food • Anything liquid or solid formed of different nutrients & utilized by the body for energy production, growth, tissue maintenance, and regulation of body functions. Diet • The whole daily consumed food. A kilocalorie • The unit of measure used to express the fuel value produced from food. It equals the amount of heat needed to raise the temperature of 1 liter of water 1°C.
  4. 4. Safe food • The food which is free of artificial or natural harmful compounds, not contaminated with infectious agents or toxins or heavy metals and not polluted by radiation. Food security • The availability of food in adequate quantity & quality with reasonable price at any time for all groups of population. Food supplementation • Providing of food of a high nutritive value to vulnerable groups at low prices or free of charge e.g., milk powder for infants, flour, cheese & cereals for pregnant & lactating mothers. Food fortification • Addition of a certain nutrient to a particular food in which it is deficient to improve its nutritive value, e.g, addition of I2 to table salt, iron to flour, vitamins A & D & E to vegetable oils & powdered milk. Food enrichment • Addition of certain nutrients to food which lost during food baking or processing as addition of vit.B to flour & vit.C to milk.
  5. 5. FOOD CONSTITUENTS: Macronutrients: Nutrients which are needed in grams as: carbohydrates, proteins and fats. Micronutrients: which are needed in milligrams or micrograms as vitamins, minerals and trace elements. Water: it forms about 70% of body weight.
  6. 6. CARBOHYDRATES Formed for C-H- O atoms. Carbon atom is the source of energy. They are mainly found in plant foods (made by photosynthesis). Only animal food containing crab. is milk “source of sugar (lactose) for babies before they be able to eat solid food” About 50-55% of daily energy requirements “recommended by the guidelines for healthy diet”.
  7. 7. FUNCTIONS OF CARBOHYDRATES: Provide energy: 1 gram → 4 kcals. Spare protein from burning for energy production. Aid in more efficient & complete oxidation of fats for energy production. Dietary fibers
  8. 8. Functions of soluble fibers (as white apple, pectins, beans….etc) • ↓ total serum cholesterol level because they absorb bile salts in intestine, so liver consumes more amount of cholesterol to form more bile salts. • Help promote normal blood glucose level (delay digestion). • Enhance body use of insulin in insulin resistance syndrome as all types of fibers contribute to low glycaemic index meals. Functions of insoluble fibers (as apple skin, cellulose….etc) • Absorb water 10-15 times their volume, so add bulk to food. • Satiating action. • Stimulate intestinal motility, so prevent constipation→ ↓colonic pressure & ↓ absorption of toxins and carcinogens from colon.
  9. 9. DISORDERS OF EXCESS CARBOHYDRATE INTAKE: (EXCESS SUGAR INTAKE) Obesity (with its complications). Dental caries (sucrose is cariogenic). ↑ Insulin output • ↑Blood triglycerides→↑fat deposition & atherosclerosis • ↑ tendency for blood clotting. • More rapid return to hunger pains after a big meal.
  10. 10. LIPIDS All fats are lipids but not all lipids are fats
  11. 11. FATS: Formed of C-H-O atoms with greater concentration of carbon → more energy values “1gm →9 kcals”. Fats in our bodies (in adipose tissue) 95% are triglycerides which are formed of 3 fatty acids + 1 molecule glycerol (water-soluble carbohydrate) which allows the transport of fats through the water-based blood stream.
  12. 12. FATTY ACIDS: ARE CLASSIFIED INTO Saturated F.A. (SFA): hard in room temp., mainly animal fats, coconut oil, palm oil. Unsaturated F.A. (USFA): liquid in room temp., mainly vegetable oils (olive oil, corn oil, sunflower oil & cotton seed oil). Essential F.A.: cannot be synthesized in the body as: Linoleic, Linolenic & arachidonic acids. Non-essential F.A.: can be synthesized by the body.
  13. 13. FUNCTIONS OF FATS: • The most concentrated source of energy: 1gm →9 kcals. • Sparing burning of protein if carbohydrate deficient. • Sources of essential fatty acids. • Give satiety & add flavor and palatability to food. • Promote absorption of fat-soluble vitamins. • Insulate & control body temperature. • Protect body organ by cushioning. • Provide some structural components as cell membranes, axon sheath of nerve cells and some digestive hormones and enzymes. • Omeg-3 fatty acids: unsaturated F.A. (EPA-DHA) found in fish oils (sardines, salmon and mackerel) and have the following functions: • ↓arterial stiffness. -↓clotting time of blood. • ↓ risk of cancer. - ↓inflammation process. -↑level of H.D.L. • Functions of olive oil: (monounsaturated F.A.): • Improve insulin resistance syndrome status. -Elevate HDL level.
  14. 14. Fats in cold water fish are mainly Omega-3 F.A. which do not solidify in the very cold arctic water. Imagine that would happen to these fish if their body fat consisted of saturated fat, they would solidify and sink. Therefore, fish from cold arctic waters have to be high in Omega-3 F.A. to survive
  15. 15. TYPES OF CHOLESTEROL: HDL cholesterol has more protein than LDL or VLDL which allows more cholesterol to be taken from the body cells resulting in removal of cholesterol through the liver. High density lipoprotein cholesterol (HDL-C): Good cholesterol Very low density lipoprotein cholesterol (VLDL-C). Low density lipoprotein cholesterol (LDL-C): Bad cholesterol
  16. 16. FUNCTIONS OF CHOLESTEROL: It is a fat-related substance as it does not produce energy, formed in animal liver only, so not found in plant food (vegetable oils). Structure of adrenal & sex hormones. Synthesis of vitamin D3. Precursor of bile salts which are essential for fat digestion. Essential component in cell membrane.
  17. 17. NORMAL BLOOD LEVEL Cholesterol Total < 200 mg/dl LDL-C <130 mg/dl HDL-C >40 mg/dl for males. >50 mg/dl for females Triglycerides <150 mg/dl
  18. 18. EFFECT OF EXCESS FAT INTAKE Overweight & obesity. ↑LDL-C & triglycerides in blood → atherosclerosis & CHD. Diabetes mellitus type II & gall bladder stones. Repeated heating of vegetable oils (USFA) →transformation into SFA “junk foods with repeated frying of oils”. Margarine which is trans-FA (hydrogenated saturated vegetable oils) & promotes CVD as it ↑ LDL-C & ↓ HDL-C despite it does not contain cholesterol. Butter contains cholesterol & SFA but it ↑ both LDL-C & HDL-C.
  19. 19. PROTEINS: Proteins are formed of amino acids (C.H.O.N. atoms).
  20. 20. SOURCES OF PROTEIN (TYPES OF PROTEINS): Complete proteins: Contain the essential amino acids. Animal foods as meat, fish, milk, eggs. Incomplete proteins: Not contain all the essential amino acids & contain the other non-essential amino acids. Vegetable foods as cereals, legumes, peanuts.
  21. 21. PROTEIN REQUIREMENTS/DAY: Adult • 0.8 gm/kg BW Infant & Child • 2-3 gm/kg BW Pregnant • 2-3 gm/kg BW Lactating • 3 gm/kg BW
  22. 22. Reference protein It is an ideal protein Contains all the essential A.A. in optimal amounts for human's nutrition. Fully digestible & utilizable by the body. Examples: human milk & hen's egg.
  23. 23. FUNCTIONS OF PROTEINS Body building & growth (formation, maintenance and repair of cells). Formation of essential components: hormones, enzymes, immune cells, immunoglobulins & hemoglobin. Regulation of fluid movement of blood by control of osmotic pressure. Regulation of acid-base balance (control movement of chemical ions in & out of the cells). Production of energy: 1 gram → 4 kcals.
  24. 24. DEFICIENCY OF PROTEINS: In children: growth retardation, wasting (Kwashiorkor). Nutritional oedema. Impaired immunity & more susceptibility to infections. General muscle weakness & poor wound healing. Apathy & depression.
  25. 25. WATER Functions of Water: Aids in digestion, absorption, circulation & excretion processes. Serves as a solvent for body constituents & as a medium for all chemical reactions in the body. Carries nutrients to & waste products from cells as a part of the blood. Regulates body temperature. Involves with lubrication of the moving parts in the body. Water requirements: “Adults : 1ml/K.cal., Infants: 1.5 ml/K.cal”.
  26. 26. Vitamins • Essential compounds that can’t be manufactured by the body in sufficient amount & have to be supplied by food. • Classified into: Water-soluble vitamins: Vitamins B group & Vitamin C. Fat-soluble vitamins: Vitamins A, D, K, E. “Absorbed from the intestine with the dietary fat through the lymphatic system & stored in liver & not excreted in urine”. Minerals (essential elements) • Inorganic elements • Classified into: Major minerals: as calcium phosphorus, sodium, chlorine, potassium, magnesium and sulpher. Trace elements: as iron, zinc, iodine, selenium, manganese, chromium and copper.
  27. 27. Fat-sol. Vit. & sources Functions Deficiency Vit. A (Retinol) - Precursor: carotene In: Liver, Butter, egg yolk, Dark green leafy vegetables, Deep yellow & orange vegetables and fruits - Constituent of visual purple. - Necessary for growth and reproduction -Night blindness. -Xerophthalmia keratomalacia. -Rough dry skin. -Retarded growth. Vit. D.: - [Ergocalciferol (D2)] - [Cholecalciferol (D3)] -7-dehyrocholesterol (in skin) - formed by U.V.R in the skin In:- Cod liver oil -egg yolk -fish with bones (salmon) -Promotes absorption of calcium & phosphorus. -Favors deposition of calcium in bones. -Reduces excretion of phosphorus in urine. -Rickets (children). -Osteomalacia (adults) -Osteoporosis. Vit. E (Tocopherol): Whole grain cereals, Legumes, nuts, fish, Green leafy vegetables - Antioxidant - Hemopoiesis (protects RBCs from haemolysis) -Anemia in premature infants -RBCs hemolysis Vit. K (Mendione): Dark green leafy vegetables, Egg yolk, cheese, Green tea - Synthesized by intestinal bacteria - Formation of prothrombin and other clotting factors. - Hemorrhage
  28. 28. Vit. B1 (Thiamin): Whole grains -yeast -Organ meats - legumes - Helps in carbohydrate metabolism - Promotes good functioning of nervous system and other systems. - Beri-Beri. - Polyneuritis. Vit. B2 (Riboflavin): Whole grains, yeast -Organ meats, eggs, milk, milk products, green leafy vegetables Helps in metabolism of carbohydrates, proteins and fats. -Angular stomatitis. - Cheilosis - Cataract -Tongue inflammation Vit. B3 (Niacin): Whole grain cereals -Legumes, yeast - meat, meat organs -Carbohydrate metabolism - Pellagra - Depression Vit. B12 (Cobalamin): Animal source protein only as: meat, milk, eggs. - Hb Synthesis & Formation of RBCs. -Folic acid metabolism -Megaloblastic anemia - Neuritis Folic acid (Folacin): Dark green leafy vegetables, legumes, whole grain cereals, meats, eggs - Formation of RBCs -Megaloblastic anemia - Neural tube defect. Vit. C (ascorbic acid): Citrus fruits, tomatoes, strawberries, green leafy vegetables, green peppers, broccoli - Antioxidant - Wound healing -Collagen tissue formation -Iron absorption. -Connective tissues of blood vessels - Scurvy - Anemia -Swollen& bleeding gums
  29. 29. Major minerals Functions Deficiency Calcium (Ca++): Milk – milk products - green leafy vegetables - sardines, salmon with bones -Bone and teath formation - Aids in blood coagulation -Helps in muscles contractions -Aids in enzymatic functioning -Rickets - Osteomalacia - Osteoporosis -Poor blood Clotting Phosphorus (P3-): Milk – milk products – egg yolk – meat – nuts – legumes – whole grains -Bone and teeth formation -Energy metabolism -Aids in acid-base balance -Fragile bones -Stiff joints Potassium (K+): Banana, orange, apricots, carrots, potatoes –meats, milk, milk products -legumes, molasses, tea -Muscles contractions -Key role in acid-base balance -Aids in enzymatic reactions - ↓heart rate -bone fragility Sodium (Na+): (In sodium chloride)Common salt, naturally in vegetables and milk -Maintenance of acid-base balance -Control of muscle contractions -disturbed muscle action (muscle cramps) Magnesium (Mg++): Dark green leafy vegetables -whole grains, nuts-bran - banana – apricots - sea foods -tea – coffee -Bone and teeth formation -Protein synthesis & lipid metabolism -Regulates heart beats -C.N.S. problem, as: confusion, apathy, hallucinations - Arrhythmia -Cramps -Tremors
  30. 30. Minerals “Trace elements” Functions Deficiency Iron (Fe+++): Haeme sources: liver, red meat Non haeme source: Dark green leafy vegetables, legumes, whole grains, molasses, dried fruits -Essential for formation of haemoglobin (in RBCs) -Part of enzymes and proteins. -Iron deficiency anemia Selenium (Se): Meat, eggs, liver, whole grain cereals, sea foods, garlic -Antioxidant -↓ cancer risk -Plays a role in prevention of HIV replication -Plays a key role in immune system Iodine (I-): Fish in salt, water, vegetables grown in iodine-rich soil -Regulates energy metabolism as a part of thyroid hormone -Endemic goiter -Cretinism. Zinc (Zn++): Whole grains, wheat germ, liver, yeast, sea foods, milk -Growth & reproduction -Immunity, neurological functions & smell acuity. -Retarded growth & sexual maturation Copper (Cu++): Shellfish, liver, nuts, while grains, chocolates -Information & survival of RBCs -In lipid metabolism -Anemia -CNS problems Chromium (Cr+++): Liver, whole grains cheese, legumes, yeast -Activate enzymatic action -Enhances removal of glucose from blood -CNS problems -DM aggravation
  32. 32. These are 1000 or more newly recognized non-nutritive plant chemicals neither vitamins nor minerals and have disease preventive effects.
  33. 33. FUNCTIONS OF PHYTOCHEMICALS • Flavonoids (apples & green tea): ↓cancer lung risk. Lycopene (tomatoes & pepper): ↓cancer prostate risk “antioxidant effect 2 times as powerful as vit.A”. Antioxidant & Anti- cancer: • Reduce menopausal symptoms, osteoporosis and cancer risk. Hormonal & Enzymatic stimulation effect • Grapes, nuts, rosemary, tea, whole grains, legumes and soybeans. Anti-inflammatory & Anti-blood clotting effect • Green tea. ↓ LDL-C & ↑ HDL-C