Objectives. Opening Statements. Influencing Factors (RDA) M1 Biochemistry. Nutritional Requirements and Energy Balance. Dr.

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1 M1 Biochemistry Nutritional Requirements and Energy Balance Dr. Beckman Objectives Define Recommended Dietary Allowance" and compare with other recommended intake values. Differentiate the nutritional characteristics of carbohydrates, lipid and protein, and recite the requirements of each dietary macronutrient. Calculate body mass index (BMI), REE and DEE. 1 2 Opening Statements Nutrients are the factors and essential elements that in small amounts are required to maintain and sustain normal patterns of growth, reproduction and balance of all homeostatic mechanisms. The body relies on nutrition to provide the daily energy and the essential small molecules it needs for growth and regular maintenance. The term essential refers to the inability to of the body tissues to synthesize the molecule or at least synthesize it at a rate sufficient for proper regulation of growth and maintenance. Recommended dietary allowance (RDA) The RDA is an estimate of the amount of each nutrient required to meet the needs of 95% of the U.S. population. The RDA is not the minimal requirement for individuals rather it is intentionally set to provide a margin of safety for most individuals. 3 4 Influencing Factors (RDA) Age: nutrient requirements increase from infancy to adulthood. as a unit of body weight, children generally have the higher requirement due to rapid growth. Gender: Men typically require 20% greater dietary allowances of essential nutrients than women Other Factors: Pregnancy Lactation Severe illness Severe injury Specific Chelates that Interfere with Ion Utilization Phytate resembles inositol with 6 PO 3 groups binds iron calcium Magnesium sources: cereal grains (AKA hexaphosphoric acid) phytase: an enzyme found in grains and present in the kidneys; important in splitting phytin or pytic acid into inositol and phosphoric acid. 5 6

2 Specific Chelates that Interfere with Ion Utilization Oxalate a salt of oxalic acid produced from glycine (precipitates with calcium) sources: cranberries, chard, rhubarb, gooseberries, spinach, beet leaves should be accompanied in the diet by liberal portions of calcium foods, such as eggs, beans, and milk. Oxalic acid poisoning: acute poisoning by eating large quantities of foods rich in oxalic acid. Treat with a soluble source of calcium. Oxalosis: Autosomal recessive disease due to faulty glyoxylic acid metabolism. Oxalic acid is elevated in the urine to the point where calcium oxalate crystals form in the kidney and other body tissues. Biological Significance of Chelates Influence absorption of ions and molecules in the diet Influence metabolism and utilization of nutrients 7 8 DRI: A New Nutrition Guide Dietary Reference Intakes Dietary Reference Intakes (DRI); is an umbrella term embracing several categories of nutritional measurements for vitamins, minerals, and other nutrients. It includes: Estimated Average Requirement (EAR): The amount that meets the needs of half of the people in any one group (ex., teenagers). Recommended Dietary Allowance (RDA): The amount of any one nutrient known to protect against deficiency. Adequate Intake (AI): A range of nutrient intake that satisfies health standards for at least 75% of a population Tolerable Upper Intake Level (UL): The highest amount of a nutrient you can consume each day without an adverse effect Energy Balance 11 12

3 Energy Requirements of Humans Food The energy content of food is calculated from the heat released by the total combustion of food in a calorimeter. It is expressed in kilocalories (kcal or C) The Atwater Conversion Factors useful in determining the caloric content of fat, protein, carbohydrate and ethanol Carbohydrates Proteins Fats Carbohydrates Proteins Fats 4 kcal/g 4 kcal/g 9 kcal/g 13 Ethanol 1 ounce = grams 7 kcal/g drinking two 8 oz. glasses of wine (12% alcohol) provides approximately 380 calories. This represents more than 10% of the daily energy needs of a sedentary 14 person. BMR roughly approximates REE The daily energy expenditure (DEE) of energy can be determined by carefully recording the type and duration of all the activities within a 24 hour period and multiplying each activity by an activity factor. The sum of these activities plus the REE gives the DEE. Resting Energy Expenditure (REE) Basal Metabolic Rate (BMR): 24 x kg BW Resting Energy Expenditure (REE) Age Equation Infants 0 3 (60.9 x kg) 54 Male Adults (15.3 x kg)+679 Female Adults (14.7 x kg) Note: 1 kg = 2.2 lbs 16 Formula lbs / 2.2 = kilograms kg x 2.2 = pounds Conversions Examples A man weighing 70 kilograms weighs 154 pounds 70 kg x 2.2 = 154 lbs A woman weighing 110 pounds weighs 50 kilograms 110 lbs / 2.2 = 50 kg Daily Energy Expenditure (DEE): DEE= REE + Physical Activity + DIT Note: diet induced thermogenesis (DIT) is often ignored in DEE calculations because it is so small. Activity Levels x Hrs resting sleeping 1.0 very light cooking 1.5 light walking 2.5 moderate dancing 5.0 heavy uphill walking 7.0 Dee=Σ[(REE/24) x activity level calculation for all hrs of day] 17 18

4 Weight Gain and Loss 1 lb of fat is equal to 3500 calories or kcal Therefore, to lose a pound of fat, you must expend 3,500 calories above the DEE or consume 3500 calories less than the DEE. Assess Weight in Relation to Health: Calculate your body mass index (BMI) Your BMI estimates whether you are at a healthy weight. Being overweight puts strain on your heart and can lead to serious health problems. These problems include type 2 diabetes, heart disease, high blood pressure, sleep apnea, varicose veins, and other chronic conditions. More than 300,000 lives could be saved in the United States each year if everyone maintained a healthy weight! How to Determine Your BMI Your BMI estimates how much you should weigh, based on your height. Here are the steps to calculate it: BMI Below 18.5 BMI Chart CATEGORY Underweight Multiply your weight in pounds by 703. Divide that answer by your height in inches. Divide that answer by your height in inches again. For example, a woman who weighs 270 pounds and is 68 inches tall has a BMI of Healthy Overweight Obese Use the chart to see what category you fall into, and whether you need to be concerned about your weight. 21 Over 40 Morbidly obese 22 Exception to the BMI Index Other Assessments Body builders: Because muscle weighs more than fat, people who are unusually muscular may have a high BMI. Elderly: In the elderly it is often better to have a BMI between 25 and 27, rather than under 25. If you are older than 65, for example, a slightly higher BMI may help protect you from osteoporosis. Children: While an alarming number of children are obese, do not use this BMI calculator for evaluating a child. Talk to your child's doctor about what an appropriate weight is for his or her age. Your doctor may take your waist circumference and your waist to hip ratio into consideration. In addition, a lot of other factors influence your health. These include diet, physical activity, smoking, blood pressure, cholesterol levels, and blood sugar levels. While the exact degree to which increasing BMI levels have a bad effect on human health is unclear, most experts conclude that a BMI greater than 30 (obesity) is unhealthy. Exercise, whatever your BMI, can help reduce your risk of cardiovascular disease and diabetes

5 Waist to Hip Ratio A WHR of 0.7 for women and 0.9 for men have been shown to correlate strongly with general health and fertility. Women within the 0.7 range have optimal levels of estrogen and are less susceptible to major diseases such as diabetes, cardiovascular disorders and ovarian cancers. Men with WHRs around 0.9, similarly, have been shown to be more healthy and fertile with less prostate cancer and testicular cancer. Waist to Hip Ratio WHR has been found to be a more efficient predictor of mortality in older people than waist circumference or body mass index (BMI). If obesity is redefined using WHR instead of BMI, the proportion of people categorized as at risk of heart attack worldwide increases threefold. Other studies have found that waist circumference, not WHR, to be a good indicator of cardiovascular risk factors, body fat distribution hypertension in type 2 diabetes Macro Nutrients: Sources of Energy All energy in the diet comes from three macronutrient sources; carbohydrate, protein and fat (and ethanol if present in the diet). These are considered major macro nutrients because the consumption of these nutrients is much greater than other dietary nutrients. The vitamins and minerals are termed the micronutrients. Carbohydrates Carbohydrates make up about half of the calories consumed in the average American diet: Sugar and sweeteners 40% (mono & disaccharides) Grain products 36% (polysaccharides) Other 14% (complex ) The Blood Sugar Connection (Diabetes) Carbohydrates invoke the glycemic response The rise in blood sugar as compared to a baseline response to pure glucose The glycemic index is affected by the type of food, as well as, such factors as caloric density, fiber and fat content Complex Carbohydrates Dietary Fiber Starch and dietary fiber are the two types of complex carbohydrates Starch must be broken down through digestion before your body can use it as a glucose source Quite a few foods contain starch and dietary fiber such as breads, cereals, and vegetables: Starch is in certain vegetables (i.e., potatoes, dry beans, peas, and corn). Starch is also found in breads, cereals, and grains. Dietary fiber is in vegetables, fruits, and whole grain foods. Soluble fiber found in the following: Oatmeal Oat bran Nuts and seeds Most fruits (e.g., strawberries, blueberries, pears, and apples) Dry beans and peas Insoluble fiber found in the following: Whole wheat bread Barley Brown rice Couscous Bulgur or whole grain cereals Wheat bran Seeds Most vegetables Fruits 29 30

6 How much dietary fiber do I need each day? It's recommended that you get 14 grams of dietary fiber for every 1,000 calories that you consume each day. If you need 2,000 calories each day, you should try to include 28 grams of dietary fiber. Good Source of Fiber and Nutrients: Whole grains Whole grains refer to grains that have all of the parts of the grain seed (sometimes called the kernel). These parts of the kernel are called the bran, the germ, and the endosperm If the whole grain has been cracked, crushed, or flaked (as in cracked whole grain bread or flake cereal), then the whole grain must still have about the same proportions of bran, germ, and endosperm to be called a whole grain. When whole grains are processed, some of the dietary fiber and other important nutrients are removed. A processed grain is called a "refined" grain. Some refined grain products have key nutrients, such as folic acid and iron, which were removed during the initial processing and added back. These are called enriched grains. White rice and white bread are enriched grain products. Some enriched grain foods have extra nutrients added. These are called fortified grains Fat 90% of total lipid consists of triacylglycerol Plant sources: Consist largely of unsaturated fatty acids Animal sources: Consist largely of saturated fatty acids Essential fatty acids: linoleic, (linolenic, and arachidonic acid) Deficiency: scaly dermatitis (acylglucoylceramide in skin) Protein Protein (typically g/day), remember this can be based on body weight too. Essential amino acids: P VT TIM HALL Biological value (BV) of proteins Examples of Protein Combinations Based on level of EAAs Animal proteins have high biological value Plant proteins have limiting amino acids (deficient in Lys, Met, Trp, or Thr) Grains (cereal) lack Lycine, whereas, beans lack Methionine Thus, BV computed based upon food mixtures (0.8 g/kg BW) Middle East Mexico Indians America bread/cheese beans/corn wheat/legumes cereals/milk 35 36

7 Protein Recommendations If one essential amino acid is limiting (missing), a certain protein or set of proteins will not be formed, especially in the growing years. In adults, this leads to negative nitrogen balance, where dietary nitrogen intake is less than the nitrogen excreted. Infants require EAA to be 35% of the total protein intake. Adults require EAA to be 20% of the total protein intake. Animal protein is greater than 90 95% digestible. Plant protein is generally only about 70 75% digestible. Protein Disorders Protein Malnutrition Developed countries (hospital patients) Underdeveloped counties Inadequate intake of protein (Kwashiorkor) Characterized by edema, de pigmented hair, anorexia, changes in serum proteins, and enlarged fatty liver. Calorie Malnutrition Inadequate intake of energy (Marasmus) Characterized by arrested growth, extreme muscle wasting (emaciation), weakness, and anemia. (No edema) Examples Dietary Goals: Guidelines for Americans Kwashiorkor Marasumus Carbohydrate Fat Protein 39 40