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BSC Zoology - Nutrition and Digestion > Lecture 19- Human nutrition > Flashcards

Lecture 19- Human nutrition Flashcards

1
Q

What are the important principle in human nutrition?

A
  • Adequacy: enough of all essential nutrients, fiber and energy
  • Balance: don’t rely on one type of food for everything
  • Energy Control: don’t overeat
  • Moderation: not too much or too little of anything.
  • Variety: the spice of life; include a large number of different foods in your diet.
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2
Q

What are the USDA dietary guidelines?

A
  • Designed to promote population-wide dietary changes to reduce nutrition-related chronic disease.
  • Updated every 5 years (started in 1980)
  • Designed to answer question “What should I eat?” • 3 basic messages…
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3
Q

What is the aim for fitness in humans?

A
  • Aim for a healthy weight

* Be physically active each day (at least 30 minutes/day)

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4
Q

How do you build a healthy base with nutrition?

A
  • Let the Pyramid guide your food choices (to be discussed next) • Choose a variety of grains daily, especially whole grains
  • Choose a variety of fruits and vegetables daily
  • Keep food safe to eat
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5
Q

How to choose sensibly?

A
  • Choose a diet that is low in saturated fat and cholesterol and moderate in total fat
  • Choose beverages and foods to moderate your intake of sugars • Choose and prepare foods with less salt
  • If you drink alcoholic beverages, do so in moderation
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6
Q

What is the food guide pyramid?

A
  • Concept first published in 1916: focused on increasing sugar and fat intake!
  • 1950-1970: “Basic Four Food Groups” implied that we should consume equal amounts from each
  • 1992: first “pyramid” published; revised in 1996 and 2000; visual representation of USDA Dietary Guidelines
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7
Q

What is the foods vs nutrients debate?

A
  • Guidelines suggesting types of foods that we should eat
  • USDA Dietary Guidelines
  • USDA Food Guide Pyramid
  • Guidelines suggesting what and how much nutrients we should consume
  • Recommended Dietary Allowances (RDA)-”old”
  • Dietary Reference Intakes (DRI)- ”new”
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8
Q

What is a nutrient requirement?

A
  • How much of each nutrient the body requires to maintain physiologic functions and internal reserves.
  • This definition is evolving.
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9
Q

What are the recommended dietary allowances? (RDAs)

A
  • Values represent best estimates of how much of a nutrient intake is required to meet the requirements of practically all healthy individuals.
  • First published in 1941 by the Food and Nutrition Board of the National Academy of Sciences; now in 10th edition.
  • Being phased out as most important nutrient reference and replaced by the DRIs.
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10
Q

What are the dietary reference intakes? (DRI)

A
  • Set of reference values for nutrient intakes to be used in assessing and planning diets for healthy people.
  • Estimated Average Requirement (EAR).
  • Recommended Dietary Allowance (RDA). • Adequate Intakes (AI).
  • Tolerable Upper Intake Levels (UL).
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11
Q

What is the estimates average requirements? (EAR)

A
  • Nutrient intake level estimated to meet the needs of 50% of a particular population.
  • Recognizes possible health benefits beyond basic physiologic function.
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12
Q

What is an important point to remember with the guidelines?

A
  • Note that many factors (environmental and genetic) interact to determine one’s true requirements.
  • Biochemical tests are required to determine true requirements.
  • Thus, DRIs still represent estimates of requirements for individuals.
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13
Q

What are the ‘new’ recommended dietary allowances (RDA)?

A
  • EAR now required in order to set RDA.
  • Thus, some nutrients do not have “new RDAs.”
  • Still not always an accurate measure of individual requirements. • Very often overestimates requirements.
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14
Q

What is adequate intake (AI)?

A
  • Used when there isn’t enough scientific data to determine EARs.
  • Often determined by documenting normal intakes of healthy people. • All DRI values for infants are AI levels; based on intake of breast milk.
  • When AIs are used, this reflects lack of knowledge and need for more research.
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15
Q

What are the tolerable upper intake levels (UI)?

A

• Maximal intakes that are thought to be safe.
• Recognition of increasing use of dietary supplements and applies to
nutrient intake from supplements alone!
• More is not always better!
• Not to be used as a target intake for any population.

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16
Q

What is the daily reference values? (DRV)

A

• Daily Reference Values (DRV).
• Established to help consumers follow recommendations for health and
disease prevention (Dietary Guidelines).
• Based on 2000 kcal diet (average).
• Suggest maximal levels of intake for fat, saturated fat, cholesterol and sodium.
• Suggest intake levels for protein, carbohydrate and fiber.
• Note that some are controversial.

17
Q

What are the references daily intakes?

A
  • Reference Daily Intakes (RDI).
  • Highest amount of each nutrient recommended for any adult age group.
  • May overestimate, but never underestimate, need. • Based on “old” RDAs.
  • Will probably be revised using new DRIs.
18
Q

What is the appropriate various standards?

A

• Know your target group: population (EAR) or individual (RDA or AI). • Public health programs tend to rely on RDAs (thus, almost all
individuals’ needs are met).
• Use as comparison values for assessing individual diets.

19
Q

How to choose foods to get nutrients?

A

• Food Labels
• Regulated by the Food and Drug Administration (FDA), except for meat
products.
• 1990-Nutrition Labeling and Education Act passed by Congress requiring labeling of foods.
• 1994-”Nutrition facts” labels appeared

20
Q

What are the mandatory components of a food label?

A
  • Statement of identity
  • Net contents of package
  • Manufacturer
  • List of ingredients (in descending order, by weight)
  • Nutrition information
  • This includes added water (unless
21
Q

What are the nutrition facts on labels?

A
  • Must be on most food labels • Serving size (standardized)
  • # Servings/container
  • % “Daily Values”
  • Represents needs of “average” person
  • Based on Reference Daily Intakes (RDIs) and Daily Reference Values (DRVs)
  • Required: fat, saturated fat, cholesterol, fiber, sugar, protein, vitamins A and C, calcium and iron. Trans fatty acids (added in 2006)
  • Daily values for lower and higher calorie requirements
22
Q

What are the examples of descriptive terms?

A

• Examples: sugar free, low fat, light, healthy • Tightly regulated

23
Q

What is the continuum of nutritional status?

A
  • Under-nutrition: associated with nutritional deficiency diseases and protein/energy malnutrition
  • Common in 1800s and early 1900s
  • Now only associated with extreme poverty, alcoholism, illness and eating disorders
  • Over-nutrition: consumption of more than is necessary for health
  • Highly associated with many chronic diseases (heart disease, stroke, cancer)
  • Good health lies between these extremes
24
Q

What are the ABCDs of nutritional assessment?

A
  • Anthropometric data
  • Biochemical tests (blood, urine or feces samples)
  • Clinical observations: signs and symptoms of nutritional deficiencies • Dietary intake
25
Q

What is the anthropometric assessment?

A
  • Physical measurements of the body

* Body Dimensions (weight, height, and circumferences) • Body Composition (fat, muscle, water)

26
Q

Why do we care about height and weight?

A
  • Used to assess risk for certain diseases
  • Used to help monitor progression and severity of certain diseases • Assess growth and development of babies and children
  • Assess health and progress of pregnancy
27
Q

What other dimensions to consider?

A
  • Circumferences of head (infants), waist and hips can be measured. • Increased waist to hip ratio has been “linked” to disease risk.
  • Head circumference can indicate brain development in infants.
28
Q

Why do we care about body composition?

A
  • Body fat is a risk factor for chronic diseases (heart disease, some cancers)
  • Assessment of fitness of athletes and others
29
Q

How do you measure body composition?

A
  • Skinfold calipers used to estimate body fatness.

* Others: underwater weighing, x-ray methodologies (DXA).

30
Q

How to use RDAs for dietary assessment?

A
  • RDA group: Female 19-24
  • RDA Calcium: 1200 mg
  • Dietary Assessment Estimates intake of: 1000 mg • 1000 mg / 1200 mg x 100 = 83% of RDA
  • Should you be concerned?
31
Q

What is the rule of thumb with intake? (if you should be concerned when getting lower or higher percentage of intake)

A
  • Intake > 75% RDA: lower risk

* Intake

32
Q

What are the basics of body weight management?

A
  • The “Energy Balance Equation”
  • Energy In = Energy Out + Energy to Stores
  • Remember that energy can be neither created nor destroyed. • If you eat it, it has to either be used or stored.
  • This is not rocket science…
33
Q

How do you estimate body fat?

A
  • Body Mass Index (BMI)
  • Wt (kg) / ht2 (m2)
  • NIH guidelines (1998)
  • Normal:19-24.9kg/m2
  • Overweight: 25-29.9 kg/m2
  • Obese: >30 kg/m2
  • Controversial
34
Q

What are the issues with obesity and health?

A
  • 55% of American adults overweight or obese
  • Related to higher risk for
  • High blood pressure • Heart disease/stroke • Diabetes
  • Cancer
35
Q

What are the issues with weight regulation?

A
  • Current theories recognize the many environmental and genetic interactions
  • Genetics (molecular biology) thought to explain 50-90% of variation in body fat.
  • Sociocultural influences
  • Perception of ideal weight
  • Availability of food
  • Social aspect of eating
  • Age and Lifestyle • Exercise!
36
Q

What are some of the current theories regarding weight of humans?

A
  • Race/ethnicity (nature or nurture?) • Socioeconomic status
  • Poverty is associated with higher rates of obesity.
  • Employment
  • Employed women are thinner… • Chicken or egg?
  • Psychological factors
  • “restrained eaters”
  • “binge eaters”
  • “yo-yo” dieting (weight cycling)
37
Q

What are the components of weight management?

A

• Components
• Diet composition (energy in)
• Positive or negative energy balance?
• Is a particular macronutrient to blame?
• 1950-1960: carbohydrates were blamed
• These diets “successfully” help people lose weight because caloric intakes are low.
• 1970-1990: “pyramid power” suggested that proteins (or fats) were to blame!
• 1990-2003: carbohydrates bad again.
• Variety and moderation the key (again).
-• Physical Activity (energy out)
• Also decreases caloric intake by • Decreasing stress
• Produces feelings of self-worth
• Provides socialization
• Doesn’t need to be strenuous to work!
• Behavioral changes that focus on identifying cues that cause
unhealthy eating
• Where does fat go when you lose weight?

38
Q

How do you burn fat?

A 
• The act of metabolising triglycerides stored in adipose tissues
• Average fatty acid’s:
• Oleate C18 H34O2
• Palmiate C16H32O2
• Linoleate C18H32O2
• All esterify to C55H104O6
• Oxidation → 55CO2 + 52H2O + energy
• Complete oxidation of 10kg human fat requires 29kg of inhaled O2
-you breathe out the fat when burning
39
Q

What are some examples of changes in knowledge about diet?

A
  • Key examples:
  • Cholesterol and fats
  • Eggs
  • Dairy
  • Low fat • Etc.
  • This is difficult for the general public to comprehend and follow

BSC Zoology - Nutrition and Digestion (24 decks)

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