Diet & Exercise
Amino acids
• Amino acids are the building blocks of proteins.
· The human body can synthesize all of the amino acids necessary to build all human proteins except for the ten amino acids called the Essential Amino Acids: isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, histidine, arginine.
· Amino acids are typically found in meat and dairy products.
· Amino acids can also be supplied by a combination of cereal grains like corn, wheat, rice with legumes like beans and peanuts.
· Some popular food combinations contain the ten essential amino acids completing your protein requirements:
Mexican corn and beans
Japanese rice and soybeans
Cajun red beans and rice
Reference: Department of Health and Human Services and Department of Agriculture: Dietary Guidelines for Americans 2005
February 4, 2009
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Recommended Dietary Allowances (RDAs)
· Nutritional requirements have been commonly expressed by Food and Nutrition Board of the National Academy of Sciences in the form of the Recommended Dietary Allowances (RDAs).
· Recommended Dietary Allowances RDAs have been established for:
· carbohydrate intake
· protein intake
· water-soluble vitamins: thiamine, riboflavin, niacin, vitamin B6, folate, vitamin B12, and vitamin C
· fat-soluble vitamins: A, D, and E; and K
· minerals: copper, phosphorus, magnesium, iron, zinc, iodine, molybdenum, and selenium.
February 4, 2009
Minerals
• Minerals essential for normal function are grouped as:
· Major minerals:
calcium
magnesium
phosphorus
·Electrolytes:
sodium
potassium
chloride
· Trace elements: iron, zinc, copper, manganese, molybdenum, fluoride, iodine, cobalt, chromium, and selenium.
February 4, 2009
Vitamins
• Vitamins are organic molecules required by the body for a variety of essential functions.
· Water-soluble vitamins are: thiamine, riboflavin, niacin, vitamin B6 (pyridoxine), vitamin B12 (cobalamin), folate, pantothenic acid, biotin, and vitamin C (ascorbic acid).
· Fat-soluble vitamins are: Vitamin A, Vitamin D, Vitamin E, and Vitamin K.
February 4, 2009
Cholesterol
• Cholesterol is one of the major components of cell membranes.
· Cholesterol is synthesized by the body and therefore is not an essential nutrient.
· Diets that contain large amounts of cholesterol partially inhibit the body’s ability to make cholesterol but ultimately there is an increase in serum cholesterol concentrations because of suppression of synthesis of low-density lipoprotein receptors.
· Average American diets contain approximately 450 mg/d of cholesterol, but 300 mg or less per day is optimal.
February 4, 2009
Dietary fat
• Dietary fat is the most concentrated source of food energy equal to about 9 kilocalories per gram.
· Dietary fat also provides the essential fatty acid linoleic acid which is very important in normal metabolism.
· Other than the need for adequate quantities of linoleic acid, there is no specific requirement for dietary fat.
· Diets containing as little as 5-10% of total calories as fat appear to be safe and well tolerated.
• Dietary fats are composed primarily of fatty acids and dietary cholesterol.
· Fatty acids molecules contain either no carbon double bonds (saturated), one carbon double bond (monounsaturated), or more than one carbon double bond (polyunsaturated).
· Saturated fatty acids are associated with increased serum cholesterol.
· Polyunsaturated and monounsaturated fatty acids lower serum cholesterol.
· Trans-fatty acids are a particular form of unsaturated fat found in partially hydrogenated vegetable oils and is known to raise serum cholesterol levels.
· Saturated fats are solid at room temperature and in general are derived from animal foods.
· Unsaturated fats are liquid at room temperature and in general are derived from plant foods.
· The Polyunsaturated fatty acid linoleic acid is an essential nutrient and is required by the body for the synthesis of arachidonic acid, the major precursor of prostaglandins.
· Deficiency of linoleic acid results in dermatitis, hair loss, and impaired wound healing.
· Approximately 5 grams of linoleic acid per day is required to prevent essential fatty acid deficiency.
February 4, 2009
Dietary fiber
• Dietary fiber is that portion of plant matter that cannot be digested or absorbed by the human intestine.
· Fiber increases the bulk of the stool and helps excretion.
· Diets high in dietary fiber are associated with a lower incidence of digestive and cardiovascular diseases.
February 4, 2009
Carbohydrate
• A small amount of carbohydrates (approximately 100 grams per day) are necessary to prevent starvation-induced fat breakdown.
·Dietary carbohydrates include:
· simple sugars
· complex carbohydrates (starches)
· indigestible carbohydrates (dietary fiber/bran)- carbohydrates that are not digestible.
• Most dietary carbohydrates should come from complex carbohydrates as found in whole grains and from sugars as found in fruits and vegetables.
· Sucrose (table sugar) and other forms of concentrated (simple) sugar, such as high fructose corn syrup, are dietary sources of excessive calories and are associated with obesity and risk of diabetes.
February 4, 2009
Protein
• Protein is required for growth and for maintenance of body structure and function.
• The Recommended Dietary Allowance (RDA) for protein is:
· 56 grams of protein per day for men
· 45 grams of protein per day for women.
February 4, 2009
Human Energy Expenditure
Basal energy expenditure (BEE) is the amount of energy the human body requires to maintain basic physiologic functions (heart beat, breathing, nervous activity).
Thermic effect of food (TEF) is the amount of energy expended ingesting and digesting food. This averages about 10% of the Basal energy expenditure.
Physical Activity has a major impact on energy expenditure.
February 4, 2009
