Download Chapter 7 Nutrition The science of food as it relates to optimal health

Chapter 7
Nutrition
The science of food as it relates to optimal health and performance
Physical Examination Preview
Nutrition Assessment
From the history and physical examination, assess the patient’s nutritional status, including the
following:
Recent growth, weight loss, or weight gain
Chronic illnesses affecting nutritional status or intake
Medication and supplement use
Nutrition screen
Assessment of nutrient intake
Clinical signs or symptoms of nutrient or energy deficiency
Laboratory values
Nutrition Assessment (Cont.)
Obtain the following anthropometric measurements and compare them to standardized tables:
Standing height
Weight
Calculate body mass index
Waist circumference
Calculate waist-hip ratio
Triceps skinfold (TSF) thickness and mid–upper arm circumference (MAMC)
measurements; calculate midarm muscle circumference/midarm muscle area
(MAMA)
Anatomy and Physiology
Anatomy and Physiology
Food nourishes the body by supplying nutrients and calories to function in three ways:
Provide energy for activities
Provide for building and maintaining body tissue
Regulate body processes
Anatomy and Physiology (Cont.)
The nutrients necessary to the body are classified as:
Macronutrients
Micronutrients
Water
Macronutrients
Carbohydrate, protein, and fat are referred to as macronutrients because they are required in
large amounts.
These three macronutrients provide the calories needed to produce energy in the human body.
Even though alcohol also provides calories (7/g), it is not required for any physiologic processes
by the body and therefore is not discussed in detail in this chapter.
Carbohydrate
Carbohydrate, a nutrient found mostly in plants and in milk, is considered the body’s main source
of energy.
About 365 g is stored as glycogen in the liver and muscle tissues, which provides energy for only
about 13 hours of moderate activity.
Carbohydrate (Cont.)
If more carbohydrates are eaten than are needed for energy, the excess is stored in fatty tissues
throughout the body.
It is recommended that carbohydrate content of the diet be at least 50% of total calories, with no
less than 100 g being consumed per day.
Carbohydrate (Cont.)
Carbohydrates also serve major functions in vital organs:
Liver
Sparing the use of protein for energy and participating in specific detoxifying
metabolic pathways
Heart
As glycogen stored in cardiac muscle
Central nervous system
As the only energy source to the brain
Protein
Protein, present in all animal and plant products, is essential to life.
It is a part of more than half the organic matter in the body.
Twenty different amino acids combine in different ways to form proteins.
Nine amino acids are considered essential because they cannot be manufactured by the
body and are essential for normal growth and development.
Protein (Cont.)
The major functions of protein include the following:
Building and maintaining tissues
Regulating internal water and acid-base balances
Acting as a precursor for enzymes, antibodies, and several hormones
If more protein is eaten than is needed for these major functions, the surplus either is used to
supply energy or is stored as body fat if total calorie intake is in excess of needs.
Protein (Cont.)
It is recommended that protein content of the diet be 14% to 20% of total calories, or a daily
minimum of:
13 g in infants
25 g in children
45 g in adults
Fat
Fat, which is present in fatty fish, animal, and some plant products (particularly the seeds of
plants), is necessary as the main source of:
Linolenic acid (omega-7 fatty acid)
-Linolenic acid (omega-3 fatty acid)
Fatty acids are essential for normal growth and development.
Fat (Cont.)
Other major functions of fat include the following:
Synthesis and regulation of certain hormones
Maintenance of tissue structure
Nerve impulse transmission
Memory storage
Energy metabolism
If more fat is eaten than is needed for these functions, the extra is stored in fatty tissues in the
body.
Fat (Cont.)
Some fatty tissues, especially those under the skin and around the abdominal organs, serve
additional purposes:
As a reserve store of fuel to be used when calorie intake does not meet needs
Support and protect organs from injury
Prevent undue loss of heat from the body surface
It is recommended that fat content of the diet be 25% to 35% of total calories, or at least 20 to 35
g/day.
Micronutrients
Substances that are required and stored in very small quantities by the body
Vitamins
Minerals (elements)
Electrolytes
Not used as a source of energy but are essential for:
Growth
Development
Hundreds of metabolic processes that occur daily
Micronutrients (Cont.)
Vitamins and minerals must be taken in either through food or by supplement.
Micronutrients cannot be metabolized by the body, except:
Vitamin K and biotin (produced by certain intestinal microorganisms)
Vitamin D (synthesized from cholesterol)
Niacin (synthesized from tryptophan)
Water
Most vital nutrient; adult body is 55% to 65% water.
An individual can exist without food for several weeks, but without water, an individual would last
only a few days.
Major functions:
Provide turgor to body tissues
Alter configuration of substances for metabolic processes
Transport body nutrients and wastes
Maintain stable body temperature
Water (Cont.)
There is a continual loss of water from the body by the:
Kidneys as urine
Lungs as water vapor in expired air
Skin as perspiration
Approximately 2 to 2½ L of water are lost daily, which are replaced by:
Fluids taken in
Water contained in solid foods eaten
Water produced in the body as a result of oxidative processes
Energy Requirements
Total energy expenditure
Resting energy expenditure (REE): largest
Represents the energy expended by a person at rest under conditions of stable
temperature
Basal metabolic rate (BMR) is defined as the REE measured soon after
awakening in the morning (12 hours after the last meal).
The variability is less than 10%.
Energy Requirements (Cont.)
Total energy expenditure (Cont.)
Physical activity: second largest
Estimated energy requirements (EER)
EER is defined as the average dietary energy intake (estimated calories needed
per day) to maintain energy balance in a healthy individual based on age,
gender, weight, height, and physical activity level (PAL).
Energy Requirements (Cont.)
Total energy expenditure (Cont.)
Thermogenesis: smallest
Metabolic response to food intake
Accounts for about 7% of the total energy expended during a day
Review of Related History
History of Present Illness
Weight loss
Total weight lost, compared with usual weight
Time period
Desired weight loss
Eating habits
Undesired weight loss
Associated symptoms
Preoccupation with body weight or shape
Medications
Chemotherapy, diuretics, insulin, fluoxetine, diet pills, laxatives, hypoglycemics,
herbal supplements
History of Present Illness (Cont.)
Weight gain
Total weight gained
Time period, sudden or gradual, desired or undesired, possibility of pregnancy
Change in lifestyle
Change in social aspects of eating, more meals eaten out of the home, change in
lifestyle, activity, and stress levels
Medications
Steroids, oral contraceptives, antidepressants, insulin
History of Present Illness (Cont.)
Increased metabolic requirements
Infancy, prematurity
Fever, infection, burns, trauma, pregnancy, infancy, hyperthyroidism, cancer
External losses, such as fistulas, wounds, abscesses, chronic blood loss, chronic dialysis
Past Medical History
Chronic illnesses
Diabetes, congestive heart failure, hypothyroidism, hyperthyroidism, pancreatic
insufficiency, chronic infection, inflammatory bowel disease, surgical resection of the
gastrointestinal tract
Previous weight loss or gain efforts
Weight at 25 years, maximum body weight, minimum weight as an adult
Previously diagnosed eating disorder, hypoglycemia
Family History
Obesity, dyslipidemia
Constitutionally short or tall stature
Genetic or metabolic disorder: diabetes
Eating disorder: anorexia, bulimia
Alcoholism
Personal and Social History
Nutrition
Use of vitamin, mineral, herbal supplements
Usual weight and height; current weight and height
Use of alcohol, recreational/club drugs
Adequate income for food purchases
Ability to shop/prepare foods
Typical mealtime situations
Use of supplements, tube feeding, parenteral nutrition
Dentition: dentures, missing teeth, gum disease
Infants and Children
Nutrition: breast-feeding, formula
Intake of protein, calories, vitamins, and minerals adequate for growth
Chronic illness: PKU, inborn errors of metabolism, cystic fibrosis
Congenital anomalies: cleft palate, prematurity, neurologic disorders, tongue thrust, severe
congenital heart defect
Adolescents
Nutrition
Intake of protein, calories, vitamins, and minerals adequate for growth, fad diets
Preoccupation with weight; not limited to girls
Overconcern with developing muscle mass, losing body fat
Excessive exercise
Weighs self daily, boasts about weight loss, weight goals
Omits perceived fattening foods and food groups from diet
Pregnant Women
Prepregnancy weight, age, eating patterns/disorders
Weight gain and nutrient intake during pregnancy
Potential risks: pica, alcohol, inadequate weight gain
Lactation, nutrient intake during lactation
Influence of disorders: diabetes, renal disease, others
Older Adults
Nutrition: weight gain or loss, adequate income for food purchases, interest in meals, medical
nutrition therapy needs, number of daily meals
Energy level, regular exercise/activities
Chronic illnesses: diabetes, renal disease, cancer, heart disease
Food/nutrient/medication interactions
Examination and Findings
Equipment
Tape measure with millimeter markings
Calculator
Standing platform scale with height attachments
Anthropometrics
Procedures for accurately measuring:
Height
Weight
Triceps skinfold
Table of norms for relevant age and gender groups
These measurements are useful in assessing patients’ nutritional status and risk for disease.
Anthropometrics (Cont.)
Body mass index (BMI)
Formula used to assess nutritional status and total body fat
Waist circumference
Large waist circumference often associated with increased risk for type 2 diabetes,
dyslipidemia, hypertension, and cardiovascular disease
Monitoring over time may aid in predicting disease risk for cardiovascular and obesityrelated diseases
Anthropometrics (Cont.)
Waist-to-hip circumference ratio
Not as helpful as the body mass index in assessing total body fat
An excess proportion of trunk and abdominal fat (e.g., apple-shaped body) has a higher
risk association with diabetes mellitus, dyslipidemia, metabolic syndrome, stroke,
and ischemic heart disease than does a larger proportion of gluteal fat (e.g., pearshaped body).
Determination of Diet Adequacy
The history of an individual’s food intake allows estimation of the adequacy of the diet.
24-hour recall diet
Most simple method for food intake history
Food diary
Most accurate and time-consuming method
Measures of Nutrient Analysis
Computerized nutrient analysis programs offer quickest and most efficient method of analyzing
nutrient intake.
Quickest method of estimating adequacy is simply comparing individual intake with
recommended servings and portions listed in the MyPyramid food guide.
Measures of Nutrient Analysis (Cont.)
MyPyramid food guide
Indicates number of servings from each food group
Food-based guidance to help implement recommendations for the 2010 Dietary
Guidelines for Americans
Focus on nutrient dense food.
Balancing calories
Avoid oversize portions
Half of the plate fruits and veggies
Water instead of sugary drinks
Measures of Nutrient Analysis (Cont.)
Vegetarian diets
Can meet all the recommendations for nutrients
Key is variety, as well as amounts to meet calorie needs
Five nutrients may be deficient: protein, calcium, iron, vitamin B12, and vitamin D
Ethnic food guide pyramids
Food guide pyramids for ethnic populations are available (e.g., Mediterranean, Indian,
Mexican, and Asian)
Measures of Nutrient Adequacy
An individual’s diet can be measured for nutritional adequacy based on energy needs and/or a
variety of macronutrients or micronutrients.
Energy
Fat
Protein
Vitamins, minerals, electrolytes
Fiber
Special Procedures
Triceps skinfold thickness
Approximately 50% of the body fat is present in the subcutaneous tissue layers
Correlation exists between the triceps skinfold thickness and the body’s fat content
Special Procedures (Cont.)
Mid–upper arm circumference (MAMC)
Estimate of muscle mass and available fat and protein stores
Midarm muscle circumference/midarm muscle area (MAMA)
Sensitive index of body protein reserves
Biochemical Measurement
Hemoglobin (g/100 mL)
Hematocrit (%)
Transferrin saturation (%)
Serum albumin (g/100 mL)
Serum cholesterol (CHOL) (mg/100 mL)
Serum triglycerides (TRI) (mg/100 mL)
High-density lipoproteins (HDL) (mg/100 mL)
Low-density lipoproteins (LDL) (mg/100 mL)
CHOL/HDL ratio
Serum glucose (mg/100 mL)
Hemoglobin A1c (%)
Serum folate (ng/mL)
Abnormalities
Common Abnormalities
Obesity
Excessive proportion of total body fat
Genetic, behavioral, and environmental factors contribute to the development of obesity
Excess body fat develops as a result from energy imbalance of caloric intake and energy
expenditure
Disproportionately affects some racial groups (African Americans) and those of low
socioeconomic status
Common Abnormalities (Cont.)
Obesity (Cont.)
Body fat, especially visceral fat, increases the risk for numerous health problems,
including type 2 diabetes, cardiovascular disease, dyslipidemia, and cancer.
Medications (e.g., steroids) and certain disease processes (e.g., Cushing disease and
polycystic ovarian syndrome) may cause weight gain and contribute to obesity.
Common Abnormalities (Cont.)
Anorexia nervosa
Eating disorder classified by the Diagnostic and Statistical Manual of Mental Disorders
(DSM-IV) as a psychiatric disease, characterized by low body weight and body
image distortion.
Cause unknown, but genetic, environmental, and sociocultural factors likely contribute to
the development of anorexia.
Adolescent and young adult women, usually from middle and upper class families, most
commonly affected; also occurs in adolescent boys and men.
Two types: restricting (food intake is voluntarily limited) and purging (patients engage in
purging after eating).
Common Abnormalities (Cont.)
Bulimia nervosa
Eating disorder DSM-IV classified as psychiatric disease
Cause unknown, but genetic, environmental, and sociocultural factors likely to contribute
Adolescent and young adult women most commonly affected
Two types: purging and nonpurging (episodes followed by fasting or excessive
exercising)
Common Abnormalities (Cont.)
Anemia
Lower than normal number of circulating red blood cells
Iron deficiency is most common cause
Other causes: nutrient deficiency states including B12 and folate (see Table 7-9 to
determine type of anemia based on laboratory values)
Question 1
Carbohydrates are:
A. Body’s main source of energy
B. The result of fat breakdown
C. Is broken down into amino acids
D. Acts as a precursor for enzymes
Question 2
Which of the following is a major function of dietary protein?
A. Provides energy source for brain.
B. Builds and maintains tissues.
C. Participates in specific detoxifying metabolic pathways.
D. Synthesizes and regulates of hormones.
Question 3
Water is the most vital nutrient; the major functions include all of the following, except:
A. Providing turgor to body tissues
B. Transporting dissolved nutrients throughout the body
C. Continuously lost from the body by expired air
D. Maintains thermogenesis
Question 4
The midarm muscle circumference is:
A. Well accepted as a sensitive index body protein reserves
B. Correlates with BMI
C. Used in the diagnosis of obesity
D. Helpful to determine fluid balance
Question 5
Energy expended at rest under conditions of stable temperature is identified as:
A. BMI
B. REE
C. BMR
D. Thermogenesis