Nutrition Basics This topic examines the role of personal dietary choices and the basic principles of nutrition It introduces the six classes of essential nutrients and explains their roles in health and disease It also provides guidelines for designing a healthy diet plan I Components of a Healthy Diet A The body requires proteins fats carbohydrates vitamins minerals and water about 45 essential nutrients must be obtained from food 1 The body needs some essential nutrients in relatively large amounts These macronutrients include proteins fats carbohydrates vitamins minerals and water 2 The body needs micronutrients such as vitamins and minerals in much smaller amounts B Most nutrients become available to the body through the process of digestion in which food is broken down and processed for use for normal body functions C The amount of energy in food is expressed in kilocalories kcal 1 1 kilocalorie represents the amount of heat needed to raise the temperature of 1 liter of water 1 degree Celsius a An average person requires about 2000 kilocalories per day b The difference between energy and calories is that energy is the capacity to do work and calories are used to measure energy 2 Of the six classes of essential nutrients fat supplies the most energy per gram 9 calories followed by protein and carbohydrate 4 calories per gram a Alcohol though not an essential component of our diet also supplies energy providing 7 calories per gram b It is important to consume calories wisely concentrating on nutrient dense foods D Proteins The Basis of Body Structure 1 Proteins form muscles and bones as well as parts of blood enzymes hormones and cell membranes 2 Amino Acids a Amino acids are the building blocks of proteins b Twenty common amino acids are found in food proteins i Nine amino acids are essential ii As long as foods supply certain nutrients the body can produce the other 11 amino acids 3 Complete and Incomplete Proteins a Protein sources are considered complete if they supply all essential amino acids in adequate amounts and incomplete if they do not b Most animal proteins are complete most plant proteins such as legumes and nuts c Certain combinations of vegetable proteins generally make up for the missing amino are incomplete acids in the other protein 4 Recommended Protein Intake a Adequate daily intake of protein for adults is 0 8 gram per kilogram of body weight b Most American diets contain more protein than is needed i The body converts excess protein into fat c The Acceptable Macronutrient Distribution Range AMDR for protein intake is 10 to 35 of total daily calorie intake depending on the individual s age E Fats Essential in Small Amounts 1 Fats or lipids are the most concentrated source of energy they represent stored energy and provide insulation and support for body organs a Fats provide 9 calories of energy per gram b Fats help absorb fat soluble vitamins and fuel the body during rest and light activity 2 Two fats linoleic acid and alpha linolenic acid are essential to regulating such body functions as blood pressure and contribute to healthy pregnancy 3 Types and Sources of Fats a Most of the fats in food are similar in composition including a glycerol molecule plus three fatty acids The resulting structure is called a triglyceride i Within a triglyceride different fatty acid structures result in different types of fats A fat may be 1 Unsaturated or saturated 2 Monounsaturated 3 Polyunsaturated b The essential fatty acids linoleic and alpha linolenic acids are both polyunsaturated c Different types of fatty acids have different characteristics and different effects on health i Liquid oils tend to be unsaturated and solid fats are mostly saturated ii Saturated fats are usually solid at room temperature Leading sources of saturated fat are red meats hamburger steak roasts whole milk cheese and hot dogs or luncheon meats d Most monounsaturated and polyunsaturated fatty acids are liquid at room temperature Olive canola safflower and peanut oils contain mostly monounsaturated fatty acids corn soybean and cottonseed oils contain mostly polyunsaturated fatty acids 4 Hydrogenation and Trans Fats a Hydrogenation turns unsaturated fatty acids into more solid fats to extend shelf life and prevent separation of fatty oil These solid fats are highly saturated b Hydrogenation also changes some unsaturated fatty acids to trans fatty acids It is done to transform liquid oil into margarine or vegetable shortening i Trans fats have been associated with an increase in low density lipoprotein LDL cholesterol bad cholesterol and a lowering of high density lipoprotein HDL cholesterol good cholesterol 5 Recommended Fat Intake a To meet the body s demand for essential fats i Men need 17 grams of linoleic acid and 1 6 grams of alpha linolenic acid per day ii Women need 12 grams of linoleic acid and 1 1 grams of alpha linolenic acid b Most Americans consume enough essential fats limiting unhealthy fats is a much per day greater health concern c The AMDR for total fat intake is 20 to 35 of total calories i Omega 6 fatty acids 5 10 of total calories ii Omega 3 fatty acids 0 6 1 2 of total calories d It is important to evaluate fat content but more important to look at it in the context of one s overall diet e The latest federal guidelines place greater emphasis on choosing healthy unsaturated fats in place of saturated and trans fats F Carbohydrates An Important Source of Energy fuel for high intensity exercise 2 Simple and Complex Carbohydrates 1 Carbohydrates supply energy to the brain nervous system and blood as well as provide a Simple carbohydrates add sweetness to foods and include single sugar molecules monosaccharides and double sugar molecules disaccharides i Monosaccharides include 1 Glucose most common sugar used by animals and plants for energy 2 Fructose a very sweet sugar found in fruits 3 Galactose the sugar found in milk ii Disaccharides are pairs of single sugars 1 Sucrose or table sugar fructose glucose 2 Maltose or malt sugar glucose glucose 3 Lactose or milk sugar galactose glucose b Complex carbohydrates include starches and most types of dietary fiber c Digestion breaks down carbohydrates into simple sugar molecules like glucose for absorption i Once glucose is in the bloodstream the pancreas releases the hormone insulin which allows cells to take up glucose and use it for energy ii The liver and muscles take up glucose to provide carbohydrate storage in the form of a