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N U T R I T I O N. MBC 142  4 Lectures  Dr. Usman Ghani. O V E R V I E W. Basic concepts of human nutrition Recommended daily allowances (RDA) Energy requirement in humans Macronutrients (proteins, carbohydrates, lipids, dietary fibers) and micronutrients (vitamins, minerals)

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  1. N U T R I T I O N MBC 142  4 Lectures  Dr. Usman Ghani

  2. O V E R V I E W • Basic concepts of human nutrition • Recommended daily allowances (RDA) • Energy requirement in humans • Macronutrients (proteins, carbohydrates, lipids, dietary fibers) and micronutrients (vitamins, minerals) • Nutritional diseases • Diet and cancer • Dietetic treatment (treatment of disease by diet)

  3. W h a t i s N u t r i t i o n ? • Utilization of foods by living organisms • The process of utilization is biochemical • Human nutrition has three types: • Undernutrition • Optimal nutrition • Overnutrition

  4. N u t r i e n t s a n d D i e t • Nutrients are the ingredients of food needed for normal functioning of the body • Nutrients provide energy for various body functions • Quality (what food items) and quantity (how much nutrients) are important for maintaining good health

  5. T y p e s o f N u t r i e n t s • Two types: • Macronutrients • Micronutrients

  6. M a c r o n u t r i e n t s • Nutrients needed by the body in large amounts are called macronutrients • Three types of macronutrients • Proteins • Carbohydrates • Fats • Macronutrients provide energy and building blocks of proteins, carbohydrates and fats

  7. M i c r o n u t r i e n t s • Nutrients needed by the body in small amounts are called micronutrients • Major types of micronutrients • Vitamins • Minerals / trace elements • Required for maintaining normal health and preventing various diseases

  8. N u t r i e n t s f r o m D i e t • Proteins, carbohydrates, fats • Essential fatty acids • Essential amino acids • Vitamins • Minerals • Dietary fibers • Water

  9. Recommended Daily Allowances (RDA) • RDA are the levels of intake of essential nutrients considered by the Food and Nutrition Board, USA, to be enough to meet the nutritional needs of all healthy persons • RDA varies according to age and sex

  10. E n e r g y C o n t e n t o f F o o d • Much of the food we eat is converted to ATP and other high-energy compounds • This energy is used for biosynthetic pathways, muscle contraction, nerve impulse, etc. • Energy content of food is measured in calories (Kilocalories) of heat energy released by combustion (burning) of that food

  11. One calorie is the heat required to raise the temperature of 1 gm. of water by 1oC • Proteins 4 kcal/gm • Carbohydrates  4 kcal/gm • Fat  9 kcal/gm

  12. E n e r g y E x p e n d i t u re • Depends on four factors: • Surface area of the body (height and weight) • The greater the surface area the greater the heat loss • Age • Growth and lean muscle mass • Infants have higher basal metabolic rate (rate of energy utilization in resting state)

  13. Sex • Women have lower BMR than men • Activity level • Exercise increases energy expenditure

  14. Recommended Energy Intake

  15. Some Definitions • Omnivorous: eat both meat and vegetables • Carnivorous: eat meat only • Herbivorous: eat vegetable, grass only

  16. Vegetarianism - Definitions • Lacto-Ovo Vegetarian • Lacto Vegetarian • Vegan

  17. Vegetarianism - Definitions • Lacto-ovo vegetarian: Avegetarian who consumes eggs (ovo) and milk (lacto) • Lacto vegetarian: Does not eat eggs, meat, poultry or fish/seafood of any kind, but does consume dairy (lacto) products • Vegan: A strict vegetarian who does not eat animal products, meat, fish, poultry, eggs or dairy

  18. Vegetarian and nutrient intake • Lower intake of iron • Lower intake of calcium and vitamin D • May develop megaloblastic anemia because of vitamin B12 deficiency • Most consume enough protein • Lower in total dietary fat

  19. Vegetarian diet and disease(Research results) • Lower Body Mass Index (BMI) • Ischemic heart disease lower than non-vegetarians • Lower blood pressure • Lower cancer rates compared to non-vegetarians

  20. Dietary guidelines – more about RDA • Recommended Dietary Allowance (RDA) • Developed during the 1940’s • Prevention of vitamin and mineral deficiencies • Revised every 5 year • Dietary goals • Goals for healthy diet • Health promotion and disease prevention

  21. Food PyramidUnited States Department of AgricultureCenter for Nutrition Policy and Promotion • Educational tool for public – established in 1992 • Healthy eating guide • Size of each section reflects daily servings recommended • Pyramid shape • Fats, oils and sweets occupy only a tiny triangle at the top

  22. The Food Pyramid

  23. Dietary Goals

  24. Overnutrition • Major cause of many diseases: obesity, diabetes, hypertension, etc. • High morbidity (disease) and mortality

  25. NutritionalScreening/Assessment • It is a nutrition assessment process • Identifies persons who are malnourished • Done by a physician, nurse, dietitian or other qualified health-care professional

  26. Identifies individuals who require aggressive nutrition support • Restores or maintains an individual’s nutrition status • Identifies appropriate medical nutrition therapies • Monitors the efficacy of these interventions

  27. Nutritional Importance of Proteins • Proteins supply amino acids and amino nitrogen for the synthesis of important nitrogenous compounds such as purines, pyrimidines and heme • Types of amino acids: • Essential (body can’t synthesize) • Non-essential (body can synthesize)

  28. Recommended Daily Protein Intake • RDA:0.8 gms/kg body weight • World Health Organization 10 to 15 % of total calories

  29. Recommended Daily Protein Intake(mg/Kg body wt.) • Infants (4–6 months) • 1100 • Children(10–12 year) • 1000 • Adult (Men and Women) • 800 • Pregnancy • Additional 200 • Lactation • Additional 300

  30. Essential Amino Acids • Essential amino acids are not synthesized by the body and must be supplied in diet PVT TIM HALL Phenylalanine Threonine Histidine* Valine Isoleucine Arginine* Tryptophan Methionine Lysine Leucine *Essential only in children

  31. N i t r o g e n B a l a n c e • Normal Nitrogen Balance • In a healthy person, the nitrogen intake is equal to nitrogen loss • Negative nitrogen balance • When nitrogen loss is more than intake • Positive nitrogen balance • When nitrogen intake is more than loss

  32. Protein-Energy Malnutrition • Malnutrition: • Condition/disease caused by not eating enough food or not eating a balanced diet • Malnutrition due to inadequate intake of proteins or energy • Two conditions: • Marasmus • Kwashiorkor

  33. Marasmus: • Inadequate intake of both proteins and energy (calories) • Occurs in growing children under 5 year • Usually found in poor population suffering from food shortage

  34. Clinical Features • Thin appearance • Weight loss • Small for his/her age • Poor physical/mental development • Weak immune system • Sensitive to developing infection

  35. Kwashiorkor • Inadequate intake of proteins with adequate energy intake • Clinical features • Edema (swelling of body) – Dry, weak hair • Diarrhea – Dermatitis • Weak immune system – Retarded growth • Sensitive to developing infection

  36. Excess Protein-Energy Intake • Can lead to obesity, diabetes, hypertension, coronary heart disease, etc.

  37. C a r b o h y d r a t e s • Their major role in diet is energy production • Excess carbohydrates are converted to glycogen (in liver) and triacylglycerols (fat) for storage in adipose tissue • Carbohydrate intolerances • Diabetes mellitus • Lactase insufficiency

  38. Carbohydrates • Provide 4 kcals/gram • Major energy supply to the cells • RDA: 130 grams/day for adults and children • World Health Organization • Lower limit: 55% of total calories • Upper limit: 75% of total calories

  39. Added table sugar (sucrose) honey, high fructose corn syrup, fruit juice concentrate, etc. Naturally occurring fruit (fructose) milk (lactose) Refined grains white breads, rice, pasta cereals, crackers Whole grains whole wheat breads and pasta; brown and wild rice whole oats cereals, crackers and baked goods made with “100% whole wheat flour” Carbohydrates in Food Simple Carbohydrates Complex Carbohydrates

  40. Carbohydrates Protein-sparing effect • Dietary protein requirement and CHO diet are related to each other • If CHO intake is less than 130 g/day: • more protein is metabolized • more gluconeogenesis

  41. Carbohydrates • CHO have protein-sparing effect: • inhibit gluconeogenesis from amino acids • amino acids are used for repair and maintenance of tissue protein • not for gluconeogenesis • Protein-sparing (protein-saving)

  42. Fats in the Diet • Concentrated source of energy – 9 kcals/gram • Triacyglycerols (fats) are used as energy source • Supply essential fatty acids that cannot be synthesized by the body (linoleic and linolenic acids) • Phospholipids are essential for membrane function • Help in the absorption of fat-soluble vitamins • Source of fat-soluble vitamins (A, D, E and K)

  43. Fats in the diet • Contribute to the satiety (satisfactions) of a meal • Contribute to taste and smell of foods • May stimulate appetite • Slow gastric emptying • Excessive fat intake can cause • atherosclerosis/heart disease

  44. Dietary FatFrom animals and plants • Animal fats • Usually high melting point • Solid (hard) at room temperature • Plant fats (oils) • Usually low melting point • Liquid at room temperature

  45. Recommendations for Total Fat • World Health Organization • Lower limit: 15% of total calories • Upper limit: 30% of total calories • National Cancer Institute • 30% or less of total calories

  46. Recommendations for Saturated Fat • World Health Organization • Lower Limit: 0% of total calories • Upper Limit: 10% of total calories

  47. Essential Fatty Acids • Two essential fatty acids: • α-linolenic acid (ω-3 fatty acid) • linoleic acid (ω-6 fatty acid) • Deficiency causes: scaly skin, dermatitis, reduced growth (most common in infants) • Deficiency very rare • ω-3 and ω-6 fatty acids used to make eicosanoids which appear to have cardioprotective effects • decreased blood clotting • decreased blood pressure

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