ThiQar college of Medicine Family & Community medicine dept. Nutrition Lecture 2 Third stage by:Dr. Muslim N. Saeed November 24th,2016

Nutrients (cont.) organic : A substance or nutrient that contains the element carbon. inorganic : A substance or nutrient that does not contain carbon. *the term organic is commonly used to describe foods that are grown with little or no use of chemicals. *Carbohydrates, lipids, proteins, and vitamins are organic, because they contain carbon. Minerals and water are inorganic.

Elements in the Six Classes of Nutrients

Essential nutrients: nutrients a person must obtain from food because the body cannot make them for itself in sufficient quantity to meet physiological needs; also called indispensable nutrients. About 40 nutrients are currently known to be essential for human beings.

calories: units by which energy is measured calories: units by which energy is measured. Food energy is measured in kilocalories (1000 calories equal 1 kilocalorie),abbreviated kcalories or kcal. One kcalorie is the amount of heat necessary to raise the temperature of 1 kilogram (kg) of water 1°C. *for the sake of simplicity, nutrition labels and publications intended for consumers use the term calorie with a letter “c” to represent the unit of kilocalories.

Kcalorie Values of Energy Nutrients Nutrients Energy(kcal/g) Carbohydrate 4 Fat 9 Protein 4 NOTE: Alcohol contributes 7 kcalories per gram that can be used for energy, but it is not considered a nutrient because it interferes with the body’s growth, maintenance, and repair.

To calculate the energy available from a food, multiply the number of grams of carbohydrate, protein, and fat by 4, 4, and 9, respectively. Then add the results together. For example, 1 slice of bread with 1 tablespoon of peanut butter on it contains 16 grams carbohydrate, 7 grams protein, and 9 grams fat: 16 g carbohydrate ₓ 4 kcal/g= 64 kcal 7 g protein ₓ 4 kcal/g= 28 kcal 9 g fat ₓ 9 kcal/g =81 kcal Total 173 kcal.

Dietary Reference Intakes (DRIs) Dietary Reference Intakes (DRIs) A set of nutritional reference values that applies to healthy people. The DRIs for most nutrients consist of four values: • Estimated Average Requirement (EAR) • Recommended Dietary Allowance (RDA) • Adequate Intake (AI) • Tolerable Upper Intake Level (UL)

Estimated Average Requirement (EAR) The average daily nutrient intake level estimated to meet the requirement of half of the healthy individuals in a particular life stage or gender group. Recommended Dietary Allowance (RDA) The average daily amount of a nutrient considered adequate to meet nutrient needs of healthy individuals in a particular life stage and gender group.

Adequate Intake (AI)the average daily amount of a nutrient that appears sufficient to maintain nutrient needs of healthy individuals . Its used as a guide for nutrient intake when an RDA cannot be determined. Tolerable Upper Intake Level (UL) The maximum daily amount of a nutrient that appears safe for most healthy people and has no adverse health effects to individuals in a particular life stage and gender group.

The Estimated Energy Requirement (EER) The Estimated Energy Requirement Is the Intake Predicted to Maintain a Healthy Weight The Estimated Energy Requirement (EER) is defined as the average dietary energy intake that is predicted to maintain energy balance in a healthy adult. This dietary intake is defined by a person’s age, gender, weight, height, and level of physical activity that is consistent with good health. Thus, the EER for an active person is higher than the EER for an inactive person even if all other factors (age, gender, and so forth) are the same.

Acceptable Macronutrient Distribution Ranges (AMDR) A range of intakes for a particular energy source that is associated with reduced risk of chronic disease while providing adequate intakes of essential nutrients.

Acceptable Macronutrient Distribution Ranges (AMDR)

Proteins: Amino Acids Proteins are large, complex molecules made up of amino acids found as essential components of all living cells. Although proteins are best known as a part of muscle mass, they are in fact critical components of all tissues of the human body, including bones, blood, and hormones. The proteins in our bodies are made from a combination of building blocks called amino acids.

Proteins cont. -Main structural materials in the body (l/6th) -17% of the body weight -A major part of bones and muscles -Important in blood, cell membranes, enzymes, and immune factors -Provide energy for the body-on average, 4 kcal/ gm -The human body contains 30,000 different kinds of proteins -And about 3000 have been studied

Amino acids (AA) They are smaller units of proteins AA are found in food and stated to be needed by the human body:

essential amino acids Amino: acids not produced by the body so that they must be obtained from food. nonessential amino acids :Amino acids that can be manufactured by the body in sufficient quantities and therefore do not need to be consumed regularly in our diet.

Essential and non-essential AA

functions of proteins 1-Proteins Contribute to Cell Growth, Repair, and Maintenance -Red blood cells live for only 3 to 4 months and then are replaced by new cells that are produced in bone marrow. -The cells lining the intestinal tract are replaced every 3 to 6 days. 2-Proteins Act as Enzymes and Hormones. Ex: the enzyme phosphofructokinase (PFK) break down glucose and use it for energy during exercise. -insulin, is a hormone facilitate the transport of glucose into cells. -glucagon and thyroid hormone. 3-Proteins Maintain Fluid and Electrolyte Balance When the level of proteins in the blood is insufficient, edema can result. 4-Proteins Maintain Acid–Base Balance By buffering acids and bases, proteins maintain acid–base balance and blood pH.

5-Proteins Maintain a Strong Immune System Antibodies are special proteins that are critical components of the immune system. 6-Proteins Serve as an Energy Source Certain amino acids can be converted into glucose via gluconeogenesis. 7-Proteins Assist in the Transport and Storage of Nutrients Transferrin is a transport protein which carries iron in the blood. Ferritin, is an example of a storage protein: it is the compound in which iron is stored in the liver.

Situations of protein supplementation 1-During growth phase of infancy 2-Donation of blood 3-Excessive menstruation 4-Hemorrhage after an accident 5-Destruction of tissues due to burn 6-Wasting diseases such as TB 7-Pregnancy and lactation

Protein requirement for vulnerable groups -During pregnancy increased by about 14 g per day. -During lactation by about 25 gm per day (during 0 to 6 months). -Young children (0-6 years) require proportionately more protein for each kilogram of body weight than adults.

Questions