Transcript Primary functions Fat-soluble vitamin

Essentials of Biology
Sylvia S. Mader
Chapter 25
Lecture Outline
Prepared by: Dr. Stephen Ebbs
Southern Illinois University Carbondale
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
25.1 Nutrition
• All aspects of bodily function depend upon
proper nutrition.
• A nutrient is a component of food that is
needed for a specific physiological
function.
• Deficiency disorders occur when the body
lacks a nutrient required for a function.
25.2 The Classes of Nutrients
• There are six classes of essential nutrients.
– Carbohydrates
– Lipids
– Proteins and amino acids
– Minerals
– Vitamins
– Water
• These nutrients may be needed in large
amounts (macronutrients) or small amounts
(micronutrients).
Introducing the Nutrients (cont.)
CLASS
Carbohydrates
ROLE
Energy, fiber
Lipids
Energy, insulation,
vitamin D synthesis
Macronutrient
Proteins
Provides essential
amino acids
Homeostasis, water
balance, cofactors
Macronutrient
Metabolism and
development
Hydration,
temperature control
Micronutrient
Minerals
Vitamins
Water
Macro or micro?
Macronutrient
Micronutrient
-
Carbohydrates
• Carbohydrates include sugars, starch and
fiber.
• Sugars can be present as
monosaccharides such as glucose or
disaccharides such as sucrose.
• Starch is a polymer used by plants to store
glucose.
Fiber
• Fiber is the indigestible carbohydrates derived
from plant material.
• Fiber is not considered a nutrient because it
cannot be digested to smaller molecules.
• Insoluble fiber is important because it stimulates
movement of feces in the bowel.
• Soluble fiber binds to compounds in the intestine
to deter their absorption and enhance their
excretion.
Fiber (cont.)
Can Carbohydrates Be Harmful?
• Carbohydrates are important because they
provide about 45% of the body’s energy needs.
• A diet containing large amounts of low-fiber
carbohydrates adds empty calories to the diet.
• Excess carbohydrates in the diet can contribute
to obesity, diabetes, and other diseases.
Lipids
• There are different forms of lipids that influence
nutrition.
– Triglycerides such as fats and oils supply cells with
energy.
– Fat is a long-term storage form for lipids.
• Triglycerides are necessary for nutrition.
– Nutritionists recommend that fats and oils should
provide 30-35% of the body’s energy.
– Triglycerides contain essential fatty acids that the
body requires for proper function.
Can Lipids Be Harmful?
• Cholesterol is a lipid that serves an
important function in cells.
• However, elevated levels of cholesterol
and fats in the blood can be detrimental to
health.
• Lipids should not be eliminated from the
diet, but should be consumed in
moderation from more nutritional sources.
Proteins
• Proteins consumed in the diet are broken down
to liberate amino acids, nine of which are
essential in the diet.
• While all foods contain protein, plant proteins
are considered “incomplete” because they
generally lack one or more of the essential
amino acids.
• This limitation can be overcome by eating
specific combinations of plant foods.
Can Proteins Be Harmful?
• Proteins should supply no more than 1015% of the calories consumed in the diet.
• Excess protein in the diet cannot be used
productively and is generally excreted as
urea in the urine.
• High protein diets can lead to some health
problems, such as dehydration, calcium
loss, and kidney stones.
Minerals
• The term minerals is applied to the 20
elements that are required for nutrition.
• Absence of a specific mineral can lead to
mineral deficiencies.
– Low iron can lead to anemia.
– Low calcium can lead to osteoporosis.
• Excess minerals in the diet, such as
sodium, can also have harmful effects.
Minerals (cont.)
Major minerals
Primary Functions
Calcium
Strengthen bones, nerve function
Phosphorus
Bone growth, energy metabolism
Potassium
Nerve function, muscle contraction
Sodium
Chloride
Nerve function, pH and water
balance
Water balance
Magnesium
Nerve and muscle function
Minerals (cont.)
Trace minerals
Primary Functions
Zinc
Protein synthesis, immune function
Iron
Hemoglobin synthesis
Copper
Hemoglobin synthesis
Iodine
Thyroid hormone synthesis
Selenium
Antioxidant
Vitamins
• Vitamins are essential organic compounds other
than carbohydrates, lipids, and proteins that
regulate metabolic activities.
• Vitamins contribute primarily to energy
metabolism and antioxidant defenses.
• Vitamin deficiencies can lead to serious disease.
Vitamins (cont.)
Water-soluble vitamin Primary functions
Vitamin C
Thiamine (B12)
Riboflavin (B2)
Niacin
Antioxidant, maintains
capillaries, bones, & teeth
Important coenzyme,
activity of nervous system
Coenzyme for energy, fat,
& protein metabolism
Coenzyme for energy, fat,
& protein metabolism
Vitamins (cont.)
Water-soluble vitamin Primary functions
Folic acid
Helps form hemoglobin
Vitamin B6
Helps form hemoglobin
Pantothenic acid
Coenzyme for fat &
carbohydrate metabolism
Coenzyme for DNA
synthesis
Coenzyme for amino acid
and fatty acid metabolism
Vitamin B12
Biotin
Vitamins (cont.)
Fat-soluble vitamin Primary functions
Vitamin D
Bone and teeth development
Vitamin E
Antioxidant
Vitamin K
Synthesis of clotting factors
Water
• The body of animals is about 60% water.
• Water also contributes to a number of
chemical reactions.
• Water is also important to the movement
of food through the intestine.
25.3 Nutrition and Health
• In the United States, poor nutrition is a
significant factor in human disease.
• For example, excess body fat contributes
to diabetes, heart disease, and certain
forms of cancer.
Are You Overweight?
• The body mass index (BMI) is to
determine if someone is overweight.
• The BMI is calculated with this formula.
weight (pounds) x 703.1
BMI 
height 2 (inches)
Normal
BMI 18.5
value
Overweight Obese
25.0
30.0
Very obese
40.0
Energy Intake Versus Energy
Output
• Aside from genetics, another factor that
contributes to obesity is a greater intake of
energy than energy output.
• Energy intake is expressed as the number
of kilocalories provided by the food eaten.
• Energy output can be measured based
upon body weight and physical activity.
Disorders Associated with
Obesity
• There are two common diseases
associated with obesity.
– In type 2 diabetes, the body develops
impaired insulin production and increased
insulin resistance, which leads to increased
fat deposition and elevated fatty acid levels.
– Cardiovascular disease affects the heart and
can lead to hypertension, heart attack, and
stroke.
Eating Disorders
• Social, cultural, emotional, and biological
factors all contribute to eating disorders.
– Anorexia nervosa is a psychological disorder
in which the person is afraid to eat for fear of
gaining weight.
– People with bulimia nervosa undergo bingepurge eating behavior.
– Some people have binge-eating disorders.
– People with muscle dysmorphia are fixated
upon their muscular development.
The Food Pyramid
• There are numerous guides, such as the
Food Pyramid, that can help consumers
plan nutritious meals.
• In 2005, the USDA released a new food
pyramid to help Americans achieve proper
nutrition.
The Food Pyramid (cont.)
Making Sense of Nutrition
Labels
• The Nutrition Facts panel on all foods contains
dietary information about that food.
– The serving size indicates the amount of that product
that is typically consumed in one sitting.
– The number of calories represent the kilocalories of
energy provided by that serving.
– The percent daily value indicates what fraction of the
recommended total daily amount for that nutrient that
would be obtained from consumption of that serving.
Making Sense of Nutrition
Labels (cont.)
Dietary Supplements
• Dietary supplements are nutrients and
plant products that can enhance health.
• Dietary supplements are regulated as
foods are, so the health benefit of a
supplement may be exaggerated.
• Dietary supplements can be detrimental if
too much is taken.