Transcript intronutr

Nutrition
“Leave
your drugs at the chemist’s
pot if you can heal your patient
with food.”
Hippocrates
Introduction to Nutrition
Nourishment:
• Provision of energy and building materials essential
for growth and survival
Nutrition:
• Study of food and nutrients, their actions,
interactions and balance in relation to health and
disease
• Overall role of nutrition is to supply
appropriate substrates to cells of various
tissues for moment to moment function
Introduction to Nutrition
Nutrient:
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a substance that nourishes
macronutrients ( protein, carbohydrate, fats)
micronutrients (vitamins, minerals, trace
elements)
Essential nutrient:
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a nutrient required for survival (species specific)
Conditionally essential nutrient
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one that may become essential under certain
conditions
Nutrients in question include, among
other things:
• oxidizable energy sources used for production of
useful chemical energy carriers such as ATP
• amino acids required for protein synthesis, as
precursors for purines & pyrimidines and other
specialized molecules
• vitamins required for a variety of specific cell
functions
• inorganic compounds such as calcium,
phosphorus, iron, etc.
Nutrient Functions
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Structural
• Muscle, bone, cytoskeletal
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Functional
• enzymatic reactions, transport, synthesis, degradation,
energy metabolism… LIFE!
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Chemical
• toxicity, pharmacologic properties- includes
phytochemicals, “functional foods”
Nutrition and Health and Disease:
Evolution of Guidelines
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Historically, dietary restrictions were
related to religious practices and law.
Late 1800’s: Germ theory of disease:
contaminated foods could act as vectors.
Early 1900’s: Vitamin theory of disease:
substances missing from diet contributing
to disease.
Nutrition and Health and Disease:
Evolution of Guidelines
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Post WW2: Framingham, Twin Cities, 7
Country studies: evaluated diet and life
style risks for development of cardiac
disease:
– Link between dietary excess and development
of chronic disease
Nutrition and Disease
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Obesity
Type II diabetes
Atherosclerotic cardiovascular disease
Hypertension
Cancer
Dental carries
Osteoporosis
Anemia
Infection
Pregnancy outcomes
Pediatric growth and development
Nutrition and Disease
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Chronic diseases: Diabetes,
Cardiovascular disease, Hypertension,
Stroke and Cancer
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Prevalent: 7 out of 10 who die each year die from
chronic disease- more than 1.7 million.
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Costly: 75% of the nation’s $1.4 trillion medical
care costs.
Preventable
Dietary Reference
Intakes
Dietary Reference Intakes (DRI)
• Reference values for meeting needs for essential
nutrients and energy
• Determined by Food and Nutrition Board of the
National Academy of Sciences
• Firmly established on basis of experimental
evidence
• Designed to prevent impairment of health from
nutritional inadequacy which is directly related to
diet and to which susceptibility is universal
RDA - DRI
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Defined as the amounts of nutrients considered
sufficient to meet the physiological needs of
practically all healthy persons in a specific group
(age and gender based) and the amount of food
sources of energy needed by members of that
group
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Designed to prevent nutritional deficiencies which
lead to specific pathological conditions
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Focus now on indicators of nutritional sufficiency
and on levels which may prevent chronic disease
RDA/ DRI’s
• deal mainly with quantities of micronutrients and
protein needed daily
• do not deal with non-nutrients and nutrients that
are not essential
• specific values are given for different age-sex
groups
• serve as standards for establishing health policy
• Terminology - Dietary Reference Intake (DRI)
has “replaced” the term RDA in United States &
Canada
DRI includes
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Estimated Average Requirement (EAR) - intake at which risk
of inadequacy is 50% (EAR is evidence-based)
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Recommended Dietary Allowance (RDA) - intake at which
risk of inadequacy is 2 - 3%
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RDA set relative to EAR: RDA = EAR + 2SDEAR
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Tolerable Upper Limit (UL) - highest level of daily intake
likely to pose no risks of adverse effect to almost all persons
in general population
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Adequate Intake (AI) - set for those nutrients without enough
evidence to develop RDA, no consistent relationship to EAR
or RDA
DRI Example: Calcium
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Infant 0-6 months:
Infant 6-12 months:
Child 1-3 y:
Child 4-8 y:
Males/Females 9-13, 14-18
Males/Females 19-30, 31-50
Males/Females 51-70, >70
Pregnancy
Lactation
210 mg
210 mg
500 mg
800 mg
1300 mg
1000 mg
1200 mg
same as age group
same as age group
New Macronutrient Guidelines and DRI’s
announced recently (Sept. 2002)
For ages >19 years old (% of total calories)
• Carbohydrates:
45 - 65%
• Fats:
25 - 35%
• Protein:
10 - 35%
• Fiber: 25-38 g per day
• Essential fatty acids: w-3’s new
• Increased exercise recommended:
• 60 minutes per day of moderate activity for
children and adults
DRI’s and Food Labels
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Daily Values for nutrients listed on food
labels as required by FDA
Reference Daily Intake for vitamins and
minerals
Uses RDA’s for 18 y/o male (highest RDA)
except for iron (19-30 y/o female)
Dietary Guidelines
Dietary Guidelines
• Differ from DRI in several aspects
• Much more general than DRI
• Primarily deal with quantities of certain foods
and nonessenteial dietary components
(e.g., fiber, cholesterol, saturated fat, etc.)
and proportions and types of energy sources
judged desirable in healthful diets
Dietary Guidelines
• advice on selecting foods to achieve
nutritionally adequate diet
• deal mainly with proportions of energyyielding nutrients in diet
• include advice on consumption of such nonnutrients as fiber and cholesterol
• recommendations are general, without
specification for different segments of the
population
Dietary Guidelines
• are health policy proposals
• directed toward prevention of chronic diseases
for which diet is a potential modifying factor
and to which susceptibility is highly variable
• evidence mainly indirect from observations
between diet and disease incidence
Consensus Dietary Guidelines
Circulation 100:450 (1999)
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The Unified Dietary Guidelines:
American Cancer Society,
American Dietetic Association,
American Academy of Pediatrics,
National Institutes of Health and
American Heart Association.
Consensus Dietary Guidelines
Circulation 100:450 (1999)
• Saturated fat < 10% of calories
• Total fat < 30% of calories
• Polyunsaturated fat < 10% of calories
• Monounsaturated fat < 15% of calories
• Cholesterol < 300 mg/day
• Carbohydrates > 55% of calories
• Total calories to achieve and maintain desirable weight
• Salt intake limited to < 6 g/day
Consensus Dietary Guidelines
Circulation 100:450 (1999)
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The consensus panel concluded that for many
individuals the recommendations could best be
achieved by following U. S. Dietary Guidelines
and Food Guide Pyramid
USDA Food Guide Pyramid
USDA Food Pyramid (1992)
Fats, Oils & S weets
US E S PARINGLY
Milk, Yogurt &
Cheese Group
2-3 S ERVINGS
Vegetable Group
3-5 S ERVINGS
Meats, Poultry, Fish,
Dry Beans, Eggs & Nuts
2-3 S ERVINGS
Fruit Group
3-5 S ERVINGS
Bread, Cereal,
Rice & Pasta Group
6-11 S ERVINGS
Nutrition and Your Health:
Dietary Guidelines for Americans
USDA & USDHHS 5th ed., May 2000
Aim for Fitness
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Aim for a healthy weight
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Be physically active
Build a Healthy Base
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Let the Pyramid guide your food choices
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Choose a variety of grains daily, especially whole grains
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Choose a variety of fruits and vegetables daily
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Keep food safe to eat
Choose Sensibly
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Choose a diet that is low in saturated fat and cholesterol
and moderate in total fat
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Choose beverages and foods to moderate your intake of
sugars
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Choose and prepare foods with less salts
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If you drink alcoholic beverages, do so in moderation
Criticism of USDA Food Guide
Pyramid
USDA Food Pyramid as annotated by
W. C Willet in Science 264 : 532 - 537 (1994)
Low-fat products are
preferable. Calcium
supplements are effective
substitutesfor preventing
fractures
Importance is well
documented. Greens and
dark orange vegetables
should be included. Even
more frequent servings may
be beneficial.
Ignores critical differences in
types of fat. Saturated and
trans
fatty acids should be minimized,
but monosaturated and
polyunsaturated fats may be
beneficial
Misleading. Two or
three servings of meat
per day may be
unhealthy
Benefits are well
documented
Whole grain & minimally processed
products should be emphasized
Willet Food Guide Pyramid
From Willett, Walter C.,
Eat, Drink, and Be Healthy , Fireside, New York (2001)
Revision of Food Guide Pyramid
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Currently underway, expected 2005
Areas expected to be addressed
– Portion sizes: are currently not consistent with
portion sizes typically consumed or stated on
food labels as required by FDA
» Most problematic with grains/starches
» Pyramid suggests 6-11 servings per day, counting 1
serving as 1/2 small bagel
How are we eating?
Percent of People Meeting Recommendations for:
Total Fat ( 30% Kcal ); Saturated Fat ( < 10% Kcal); and
Fruits and Vegetables ( •
5 servings a day). (1989-91)
A few comments on
Obesity and Comorbidities
A few comments on obesity
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The most serious nutritional problem in the
United States and the industrialized world is the
marked increase in obesity
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The problem is extending to less developed
countries.
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It is growing at epidemic rates in adult
populations
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Also occurring at alarming rates in children
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Notes: *For adults Overweight includes Obese & Extremely obese
¶All values for children are for Overweight
For 1976 - 1980, 47% of adults were overweight (15% were obese)
Obesity and comorbidity risk
Table 2. Increased Risk of Obesity Related Diseases
with Higher BMI
BMI of
BMI between BMI between BMI of
Disease
25 or less 25 and 30
30 and 35
35 or more
Arthritis
1.00
1.56
1.87
2.39
Heart Disease
1.00
1.39
1.86
1.67
Diabetes (Type 2)
1.00
2.42
3.35
6.16
Gallstones
1.00
1.97
3.30
5.48
Hypertension
1.00
1.92
2.82
3.77
Stroke
1.00
1.53
1.59
1.75
Source: Centers for Disease Control. Third National Health and Nutrition Examination Survey. Analysis by
The Lewin Group, 1999.
U.S. NIH revised weight guidelines:
1994 and 1998
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Guidelines apply equally to men & women
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Guidelines do NOT allow for weight gain in middle
age
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Revisions made in response to mounting
evidence that increases in weight associated with
increased risk of premature death from heart
disease, diabetes, and certain cancers
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At each height, proposed guidelines
recommend weights that translate to a Body
Mass Index (BMI) of 18.9 - 24.9
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In medical literature, BMI is calculated by
BMI = Weight(kg)/[Height(m)]2
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Current research suggests that obesityrelated health problems begin to mount at
BMIs above 25
U. S. National Institutes of Health obesity
guidelines (June, 1998)
BMI
• Underweight
< 18.5
• Normal
18.5 - 24.9
• Overweight
25 - 29.9
• Obese (Class I)
30 - 34.9
• Obese (Class II)
35 - 39.9
• Obese (Class III)
> 40
In this unisex version:
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weights at lower end of range recommended for
persons with low ratio of bone to fat
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weights at upper end of range advised for those
with more muscular physiques
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most of us fall into the 1st category, thus DHHSNIH suggest that we aim for lower end of range
Conversion factors:
• Weight (lb) x 0.454 kg/lb = Weight (kg)
• Height (in)/39.4 = Height (m)
Conflicting Nutritional Advice
Nutrition Recommendations
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Nutrition science is a rapidly growing field
of study, many new and sometimes
conflicting findings and advice reported in
popular press.
“Guidelines” often influenced by special
interest groups.
Consumer behavior is greatly influenced by
multi-billion dollar food industry.
Recent info on consumer confusion and
negativism about nutritional advice
J. Am. Dietitics Assoc (01/01/01)
Reported survey results on conflicting advice
about “healthy diet”
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>40% were tired of hearing about foods they
should or should not eat
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~40% thought that dietary guidelines be taken
with “a grain of salt”
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70% said government shouldn’t tell people
what to eat
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