Nutrition PDF

# NUTRITION ## Definition - Science that deals with the qualitative and quantitative requirements of the diet necessary to maintain good health (growth, normal function of tissues and organs, and the production of energy). ## FOOD - Ingestible substance composed of nutrients that satisfy hunger an...

# NUTRITION ## Definition - Science that deals with the qualitative and quantitative requirements of the diet necessary to maintain good health (growth, normal function of tissues and organs, and the production of energy). ## FOOD - Ingestible substance composed of nutrients that satisfy hunger and is utilized to support growth and maintenance. ## DIET - Combination of different foods prepared to provide the full range of nutritional requirements. ## Function of Food - **Production of Energy**: Carbohydrates and fats - **Body building (growth, repair, and maintenance)**: Protein - **Protecting the body and regulating tissue functions**: Vitamins and Minerals ## Proximate Principle of Food (Basic Components) 1. Carbohydrate 2. Protein 3. Fat 4. Water 5. Dietary fiber 6. Vitamins 7. Minerals ## Energy Content of Food - Carbohydrate: 4.1 Kcal/gm - Fat: 9.3 Kcal/gm - Protein: 4.1 Kcal/gm - Alcohol: 7 Kcal/gm ## NUTRIENTS - Constituents of food necessary to sustain the normal functions of the body, to maintain optimal health and prevent chronic disease in adults. ## Essential Nutrients - Obtained from the diet. 1. **Energy Sources:** Carbohydrates, Protein, Fat 2. **Essential Fatty Acids** 3. **Essential Amino Acids** 4. **Vitamins** 5. **Minerals** ## Types of Nutrients - Classified in two groups: 1. **Macronutrients:** Required in larger amount. They are often called proximate principles of food because they form the main bulk of the food (e.g., Carbohydrate, Protein, Fat) 2. **Micronutrients:** Required in small amounts (e.g., Vitamins, Minerals) ## Essential Nutrients - Not synthesized in the body but required for normal function of the body and therefore must be supplied by food. - **Organic:** Essential amino acid, Essential fatty acid, Glucose, Fiber - **Inorganic:** Macromolecular (Macrominerals: Na+, K+, Ca++, etc.) and Microminerals: Iron, Iodine, etc. ## Balanced Diet - A balanced diet contains all the food constituents in adequate and proportionate amounts to meet the energy and nutritional requirement of an individual. - A balanced diet protects a population from nutritional deficiencies. ## Composition of a Balanced Diet - Depends upon: 1. Age 2. Sex 3. Physical activity 4. Seasons 5. Social and cultural habits 6. Economic Status 7. Country ## Criteria of a Balanced Diet 1. Age, sex, and physical activity should be considered. 2. The diet should contain all the proximate principles of food in adequate and proportionate amounts. The ration of carbohydrates, protein, and fat should be 4:1:1. 3. The daily requirement of protein should meet 10-35%. 4. Fat should be limited to 20-35% of the daily energy intake. 5. Some amount of carbohydrate rich in natural fibers should be taken. 6. The requirement of micronutrients (vitamins and minerals) should be met. 7. Salt intake should be reduced to an average of not more than 5 gm per day. 8. Within economic capacity. ## Excessive Consumption - Excessive consumption of refined carbohydrates should be avoided. Sources rich in energy, such as fats and alcohol, should be restricted. ## Dietary Reference Intake (DRI) - Estimates the amount of nutrients required to prevent deficiencies to maintain optimal health and growth. - Consists of 4 dietary reference standards for the intake of nutrients designated for specific age groups, physiologic states, and genders. ## Components of DRI 1. **Estimated Average Requirement (EAR):** Estimated average requirement of a nutrient that would meet the needs of half the healthy individuals in a specific life-stage and gender group. 2. **Recommended Dietary Allowance (RDA):** Recommended daily intake level that is sufficient to meet the needs of nearly all 97-98% individuals in a specific life-stage and gender group. 3. **Adequate Intake (AI):** Recommended daily intake level for a nutrient, when the RDA cannot be established. 4. **Tolerable Upper Intake Level (UL):** Highest level of daily intake of a nutrient that is likely to pose no risk of adverse effects. ## Factors Influencing RDA - **Age:** For different nutrients, RDA varies from infancy to children and adults (e.g, RDA for protein: 0.8 gm/kg body weight for adults, 1 gm/kg body weight for athletes, 2 gm/kg body weight for infant/children). - **Sex:** Dietary allowances for men are 20% greater than women due to large body mass. - **Physiologic condition:** During pregnancy and lactation, 20-30% above than normal women. ## Basal Metabolic Rate (BMR) - Also known as resting metabolic rate (RMR) or basal energy expenditure (BEE). - The minimum amount of energy required by the body to maintain life at complete physical and mental rest in the post absorptive state (meaning 12 hours after the last meal, and comfortable surrounding temperature 25°C). It is characterized by: 1. 12 hours fasting 2. Awake 3. Complete physical and mental rest 4. Comfortable environmental temperature and pressure ## Normal Values Of BMR - **Man:** 35-38 kcal/sq m body surface area/hour or 1800-2000 Kcal/day. - **Woman:** 32-35 kcal/sq m body surface area/hour or 1300-1600 Kcal/day ## Under Basal Conditions - Though the body appears to be at total rest, several functions within the body continuously occur. These include respiration, working rate of the heart and other organs, conduction of nerve impulse, reabsorption by renal tubules, gastrointestinal motility, and ion transport across membranes (Na+/K+ pump) ## Factors Affecting BMR 1. **Age:** In infants and growing children BMR is high due to increased body surface area. 2. **Sex:** BMR is 5% more in men than women due to muscle mass and body surface area. BMR is directly proportional to surface area (e.g., BMR is more in children than adults). 3. **Physical Activity:** BMR is directly proportional to physical activity (e.g., BMR is more in heavy workers than sedentary workers). 4. **Climate:** BMR is more in cold climates than compared to warm climates. 5. **Fever:** Per 1 % rise of body temperature BMR increases 7-10%. 6. **Starvation:** BMR decreases in starvation. 7. **Hormones:** Thyroid hormones (T3 & T4) have a stimulatory effect on body metabolism and BMR. - ↑ BMR= Hyperthyroidism - ↓ BMR= Hypothyroidism 8. **Disease Status:** In some diseases, BMR is increased and decreased. - **↑BMR:** Hyperthyroidism, Fever, Leukemia, Polycythemia, Cardiac failure, Hypertension, Infection. - **↓BMR:** Hypothyroidism, Addison’s disease, Starvation, Malnutrition. ## Significance of BMR 1. Important to calculate the calorie requirements of an individual and planning of the diet. 2. Assessment of thyroid function. ## Metabolic Rate (MR) - Energy liberated per unit time, and it is 1.2 kcal/min at rest in standard temperature and pressure. - Factors affecting MR are: BMR/RMR, Specific dynamic action of food (SDA), Physical activity, Atmospheric and body temperature, Emotional state, pregnancy and lactation, other factors ## Specific Dynamic Action of Food (SDA) - Also known as thermic effect of food. - Phenomenon of extra heat production by the body over and above the calculated calorie value, when a given food is metabolized by the body. It is known as specific dynamic action (SDA) or calorigenic action. ## SDA of Different Food 1. Protein= 30% 2. Fat= 4% 3. Carbohydrate= 6% 4. Mixed diet= 10% - Thermic response to food intake may amount to 5-10% of the TEE (Total Energy Expenditure). ## Why is SDA of Protein so High? - Proteins composed of amino acids are connected by strong peptide bonds, that require more energy to be broken in transamination, deamination, and urea synthesis processes. ## Significance of SDA - For the digestion, absorption, transport, metabolism, and storage of foods in the body, a certain amount of energy is required, which is consumed from body stores. - This is actually an expenditure by the body for the utilization of food stuffs. It is, therefore, essential that an additional 10% calories should be added to the total energy need. ## Recommended Energy Intake for Men & Women | Person | Age | Weight (lbs) | Energy Needs (Kcal) (Mean) | Range | |---------|-----------|---------------|-----------------------------|----------| | Men | 23-50 | 70 | 2900 Kcal | 2300-3100 | | Women | 23-50 | 55 | 2200 Kcal | 1600-2400 | | Pregnant | | | +300 Kcal | | | Lactating | | | +500 Kcal | | ## Roughly the Total Daily Calorie Requirement of An Adult - Light worker: 2200-2500 Kcal - Moderate worker: 2500-2900 Kcal - Heavy worker: 2900-3500 Kcal - Very heavy worker: 3500-400 Kcal ## Energy Calculation of An Individual - Sum of energy that are used for 3 energy requiring processes that occur in our body. 1. BMR/RMR: 60% 2. Thermic effect of food (SDA): 10% 3. Physical activity: 30% ## MALNUTRITION - Pathological state resulting from relative or absolute deficiency or excess of one or more essential nutrients. - It includes : 1. **Undernutrition:** Results when insufficient blood food is eaten over an extended period of time. 2. **Overnutrition:** Results when excessive quantity of food is eaten over an extended period of time. 3. **Imbalance:** Disproportion among essential nutrients with or without the absolute deficiency of any nutrients. 4. **Specific Deficiency:** Relative or absolute deficiency of any nutrients. ## Malnutrition may occur due to: 1. Lack of food 2. Lack of knowledge of food or nutrition. 3. Increased requirement 4. Refusal to take food 5. Lack of teeth 6. Diseases of GIT 7. Difficulties in digestion, absorption and assimilation 8. Surgery: Malabsorption ## Protein Energy Malnutrition (PEM) - A range of pathological conditions arising from lack in varying proportion of protein and calories occurring most frequently in infants and young children, and commonly associated with infection. - It occurs in growing children under 5 years of age. ## Classification of PEM 1. **Kwashiorkor: ** 80-60% of the standard 2. **Marasmus:** < 60% of the standard. 3. **Marasmic Kwashiorkor:** < 60% of the standard 4. **Nutritional dwarfism:** <60% of the standard. 5. **Underweight child:** 80-60% of the standard. - [Expected weight for age of Harvard standard] ## Marasmus - Occurs when calorie deprivation is relatively greater than the reduction in protein. - It usually occurs in developing countries in children younger than age 1 year when breast milk is supplemented with watery gruels of native cereals that are usually deficient in both protein and calories. ## Typical Symptoms of Marasmus 1. Arrested growth 2. Extreme muscle wasting 3. Loss of subcutaneous fat 4. Weakness 5. Anemia ## Kwashiorkor - Occurs when protein deprivation is relatively greater than the reduction in total calories. - Protein deprivation is associated with severely decreased synthesis of visceral protein. It is commonly seen, in developing countries, in children after weaning at about age 1 year, when their diet consists predominantly of carbohydrates. ## Typical Symptoms of Kwashiorkor 1. Stunted growth 2. Skin lesions 3. Depigmented hair 4. Anorexia 5. Enlarged fatty liver 6. Edema 7. Decreased serum albumin concentration ## Why Edema occurs? - It occurs due to a lack of adequate blood proteins, primarily albumin, to maintain the distribution of water between blood and tissues. - In addition, there is enlargement of the liver as a result of accumulation of fat. - Very commonly, an infection precipitates probably due to deficiency of antioxidant nutrients, such as zinc, copper, carotenoids, and vitamins C & E. ## Difference between Marasmus and Kwashiorkor | Condition | Marasmus | Kwashiorkor | |----------------------|-----------------------|------------------------| | Age | < 1 Year | 1-3 Years | | Deficiency | Deficiency of energy than protein | Deficiency of both the quantity and quality of protein | | Appearance | Like an old man | Baby or moon face | | Muscle wasting | Marked | Less obvious | | Edema | Absent | Present in lower legs, face, and arm | | Growth retardation | Severe | Less severe | | Mental change | May or may not present | Dull, apathetic, irritable| | Appetite | Usually good | Poor | | Skin changes | Usually none | Diffuse pigmented skin, desquamated like burns, dermatitis | | Hair changes | Usually none | Lusterless, brown, and thin dipigmented hair present | | Hepatic enlargement | None | Sometimes due to accumulation of fat | | Fatty liver | Absent | Present | | Serum albumin | Normal or slightly decreased | Serum albumin low or decreased | | Vitamin deficiency | Evidence of vitamin deficiency may or may not be present | Evidence of vitamin deficiency commonly found | ## Prevention of PEM - GOBIFFF - **G:** Growth monitoring - **O:** Oral rehydration therapy - **B:** Breast feeding - **I:** Immunizations - **F:** Family planning - **F:** Food supplementation - **F:** Female education ## Management of PEM 1. **Resuscitation:** This consists of correction of dehydration, edema, electrolyte disturbances, acidosis, hypoglycemia, hypothermia, and also treatment of infection. 2. **Initiation of Treatment:** This consists of refeeding with calories 150 kcal/kg/day with protein about 1.5 gm/kg/day with K, Mg, and multivitamins. 3. **Nutritional Rehabilitation:** After 3 weeks the child’s condition becomes better, during this period mothers should have been educated about nutrition and helped to obtain extra food. ## Nutritional Aspect of Proximate Principle of Food ### CARBOHYDRATE - Dietary carbohydrates are: - **Starch:** Rice, potato, wheat - **Lactose:** Milk - **Sucrose:** Fruit - **Cellulose:** Vegetables and fruits act as dietary fiber. - 1 gm of carbohydrate provides 4 kcal of energy. The adults consume 45-69% of their total calories from carbohydrates - **RDA:** - In adults, 300-500 gm/day - In absence of dietary carbohydrate, it leads to ketone body production and degradation of body protein. Minimum 100 gm/day should be taken to avoid ketone. - **Function:** - Major source of energy 50-60% - Absolute requirement for brain. - Required for oxidation of fat. - Supply energy for muscle work. - Synthesis of fat. - Synthesis of non-essential amino acids. ### Dietary Fiber - The complex carbohydrates that are not digested by human enzymes are collectively referred to as dietary fibers. - These include: - Cellulose - Hemicellulose - Pectin - Lignin - Gums and mucilage - **RDA:** Adult (20-35) gm/day - **Source:** Whole grain cereals and beans, fruits, vegetables, and legumes. - **Dietary fibers are of two types:** 1. **Soluble Dietary Fiber:** Are resistant to digestion that are not digested and absorbed in the human intestine and usually well fermented (e.g., gums, mucilages, and pectins) 2. **Insoluble Dietary Fiber:** Pass through the digestive tract largely intact and are not well fermented. (e.g., cellulose, hemicellulose, lignin) - **Advantages of Dietary Fiber:** - Prevents constipation - Adds bulk to the diet and satiety is achieved without consumption of excess calorie. - Absorb water and increase bowel motility, thus reducing exposure of the gut to carcinogens. - It slows gastric emptying and reduces the postprandial rise in blood glucose. - Reduces plasma cholesterol levels. - Eliminates bacteria toxins. - Decreases the risk of hemorrhoids, colon cancer, diverticulosis, Crohn's disease. - **Disadvantages of Dietary Fiber:** - Excessive intake of dietary fibers reduces the absorption of nutrients and may lead to deficiency disorders. It may cause flatulence and discomfort. ## Glycemic Index (GI) - GI is defined as the area under the blood glucose curves seen after ingestion of a meal with carbohydrate-rich food, compared with the area under the blood glucose curve observed after a meal consisting of the same amount (50 gm) of carbohydrate. ## Protein - Proteins have been traditionally regarded as “Body Building Foods” because they help in the synthesis of new tissues and repair worn-out tissues. - **RDA:** - 0.8 gm/kg body weight for adults - 1 gm/kg body weight for athletes - 2 gm/kg body weight for infants/children - **According to source, dietary proteins are:** - **Animal Protein:** Meat, fish, egg - **Plant Protein:** Pulses, cereals, beans. - **According to source and nutritive value, proteins are of two types:** 1. **1st Class Protein/Amino Acid Animal Protein:** The protein which contain all the essential amino acids; they are also called proteins of high biological value (e.g., meat, fish, egg). 2. **2nd Class Protein/Plant Protein:** The protein which is deficient in any one or more EAA.