Transcript Nutrition - City College of San Francisco

Nutrition
Chapter 15a
All the chemical reactions in a person’s
body constitute that person’s metabolism
Catabolic processes break down
nutrients to obtain energy & raw
materials
Anabolic processes use energy
to assemble cells & tissues
The calorie is a measure of the
amount of energy in food
• The calorie is the metric
unit of energy, the amount
of energy necessary to raise
the temperature of 1 mL of
water by 1oC
• Though they are still called
“calories”, food calories, or
Calories, are actually
kilocalories, equal to 1000
regular calories
How calories can be measured
1. All living things are composed of
4 common macromolecules
•
•
•
•
•
Nucleic Acids
Proteins
Carbohydrates
Lipids
DNA is a nucleic acid
Nucleic acids and Proteins
Proteins, made of amino acids
Nucleic acids- DNA
Carbohydrates and Lipids
Carbohydrates- glucose+
fructose= sucrose
Lipids- a fat molecule made of
glycerol and 3 fatty acids
Vitamins and Minerals
• There are 13 vitamins, and
various minerals which the
body must obtain through
diet
• Vitamins and minerals often
function as cofactors in
enzymes
• Because cofactors are
recycled, vitamins are
required in minute quantities
Human metabolism is diverse but
limited
• Though the body can
manufacture many of its
own necessary parts,
essential nutrients cannot
be manufactured and must
be obtained through diet
• Essential amino acids are
required to make all
proteins
• Essential fatty acids are
required for cell signaling
Nutrients
• Food provides
– Fuel for cellular activities
– Metabolic regulators
– Building blocks for
• Cell division
• Maintenance
• Repair
We also need water…
• Water is necessary for
– Proper cellular
environments
– Certain cellular reactions
Nutrients
• A nutrient is a substance in food that
– Provides energy
– Plays a structural or functional role to promote
normal growth, maintenance, or repair
Lipids
Lipids
• Lipids
– Fats
– Oils
– Cholesterol
• 95% of the lipids found
in food are triglycerides
– Consist of a molecules
made from three fatty
acids attached to a
molecule of glycerol
Lipids
• Fat
– A ready source of energy
– Insulation and a cushion for vital organs
– Components of the cell membrane
– Construction of myelin sheaths
– Absorption of fat-soluble vitamins
Lipids
• Fatty acids differ in their
degree of saturation
• Saturated fats
– Solid at room
temperature
– Most come from animal
sources
• Unsaturated fats
– Liquid at room
temperature
– Come from plant sources
Lipids
• A high-fat diet is associated with
– Obesity
– High blood pressure
– Atherosclerosis
– Increased risk of diabetes
– Certain cancers
• E.g., colon, prostate, lung
• Cholesterol
Cholesterol
– The structural basis for
the steroid hormones
– Low-density lipoproteins
(LDLs)
• Bad
– They deposit
cholesterol in the artery
walls
– High-density lipoproteins
(HDLs)
• Good
– They help the body to
eliminate cholesterol
Fats in the diet
• Only 20 to 30% of the
calories in the diet
should come from fats
– Most of those should be
monounsaturated and
polyunsaturated fats
Carbohydrates
Carbohydrates
• Carbohydrates
– Provide fuel for our bodies
– Found in our diet as sugars, starches, and fiber
Carbohydrates
• Dietary fiber
– A carbohydrate in plant foods that humans cannot
digest
– Good for the heart and blood vessels
• It lowers LDLs but does not lower the beneficial HDLs
Carbohydrates
• 45 to 65% of the calories in our diet should
come from carbohydrates, including both
– Simple carbohydrates
• Sugars
– Complex carbohydrates
• Starches and fiber
Figure 15a.3
Carbohydrates
• The glycemic response
– A measure of how
quickly a serving of food
is converted to blood
sugar
• The glycemic index
– A numerical ranking of
carbohydrates based on
their glycemic response
• Foods with a low
glycemic index help to
reduce the risk of heart
disease and diabetes
Proteins
Proteins
• Proteins
– The structural components of every cell
– Regulate body processes
– Are antibodies
– Can be used for energy
Proteins
• Proteins
– Chains of amino acids that are
digested and delivered to the
cells
• Human proteins contain 20
different kinds of amino acids
– The human body can synthesize
11 of the amino acids
– The remaining 9 must be
supplied by the diet
• Essential amino acids
Proteins
• Complete dietary
proteins
– Contain all 9 of the
essential amino acids
that your body cannot
synthesize
• Incomplete proteins
– Lack one or more of the
essential amino acids
Proteins
• Complementary
proteins
– Combinations of
proteins that together
supply enough of all the
essential amino acids
Proteins
• 10 to 35% of the calories in our diet should
come from a combination of plant and animal
proteins
Vitamins and Minerals
Vitamins & Minerals
• Vitamins
– Organic compounds that are needed in minute
quantities
– Usually function as coenzymes
Vitamins
Table 15a.2 (1 of 2)
Table 15a.2 (2 of 2)
Nutrients
• Vitamins
– Water-soluble
– Fat-soluble
• Except for vitamin D, our cells cannot make
vitamins and must obtain them from food
Nutrients
• Minerals are inorganic substances that are
essential to a healthy diet
Minerals
Table 15a.3 (1 of 2)
Minerals
Table 15a.3 (2 of 2)
Water
• Water
– Transports materials through our blood and lymph
– Provides a medium for chemical reactions
– Is a lubricant
– Can serve as a protective cushion
– Plays an important role in the regulation of body
temperature
Nutrition and Weight Control
• MyPyramid is a food guide for planning a
healthy diet
• Nutrients provide energy or have a structural
or functional role in the body
• Food labels help us make wise food choices
• For body energy balance, calories gained in
food must equal calories used
MyPyramid Is a Food Guide for Planning a
Healthy Diet
• MyPyramid
– A food guide released by the U.S. Department of
Agriculture (USDA) in 2005 for planning a healthy
diet
MyPyramid Is a Food Guide for Planning a
Healthy Diet
Figure 15a.1
MyPyramid Is a Food Guide for Planning a
Healthy Diet
Figure 15a.1 (1 of 2)
MyPyramid Is a Food Guide for Planning a
Healthy Diet
Figure 15a.1 (2 of 2)
MyPyramid Is a Food Guide
• A healthy lifestyle includes
– Choosing food wisely
– Staying within your calorie needs
– Engaging in physical activity
Food Labels Help Us Make Wise
Choices
• Using the information on food labels can help
you make healthy choices and compare
different brands and ingredients
Food Labels Help Us Make Wise
Choices
Figure 15a.6 (1 of 2)
Food labels can be misleading
Figure 15a.6 (2 of 2)
Body Energy Balancing
• Body’s energy
balance depends
on
– The calories
gained in food
– The calories
used
• Unused food
energy is stored
– Fat
– Glycogen
Body Energy Balancing
• The body requires
energy for maintenance
of
– Basic body functions
• Basal metabolic rate
(BMR)
– Physical activity
– Processing of the food
that is eaten
Body Energy Balancing
• Dietary guidelines for Americans include
– Fitness
– Making healthy food choices
– Avoiding foods that lead to disease
Nutrition and Weight Control
• Obesity is body weight 20% or more above the
body weight standard
• Successful weight loss programs usually
involve reducing calorie intake, increasing
calorie use, and changing behavior
• Anorexia nervosa and bulimia are eating
disorders that create caloric deficits
Obesity
• Obesity
– Body weight 20% or more above the body weight
standard
Obesity
• The Body Mass Index
(BMI)
– Evaluates your weight in
relation to your height
– Does not actually
measure % body fat
– Statistically correlates
pretty well, but there are
exceptions
Obesity
BMI does not correlate perfectly to
percent body fat
• Maintaining a
healthy weight is
important to avoid
cardiovascular
disease, diabetes,
and degenerative
joint disease
Weight Loss Programs
Figure 15a.8
Anorexia Nervosa and Bulimia
• Weight loss can be dangerous
– Anorexia nervosa
• highest mortality rate of any psychiatric
disorder
– Bulimia
• Intentional vomiting after eating
• Both can be fatal
• Eating habits associated with
these disorders is thought to be
the result of physiological, social,
and psychological factors