Download 9 Basic Nutrition Factors in Health Nutritional Factors in Health and

chapter
Nutritional
9
Factors in Health and
Performance
Basic Nutrition
Factors in Health
Marie Spano, MS, RD
Chapter Objectives
• Know when to refer an athlete to the
appropriate resource, a medical doctor, or a
sport dietitian
• Identify the protein, carbohydrate, and fat
recommendations for athletes.
(continued)
Chapter Objectives (continued)
• List the dietary recommendations for
disease prevention and overall health
• List hydration and electrolyte guidelines for
different age groups and scenarios and help
athletes develop an individualized hydration
plan
Role of Sports Nutrition
Professionals
• Varying degrees of nutrition knowledge
• Athletes with complex nutrition issues
should be referred to a team physician or
sports dietitian
• A sports dietitian is a registered dietitian
with specific education and experience in
sports nutrition
• Board Certified Specialist in Sports
Dietetics (CSSD)
(continued)
Role of Sports Nutrition
Professionals (continued)
• Responsibilities of the registered dietitian
include the following:
– Translate the latest scientific evidence into practical
sports nutrition recommendations
– Assess and analyze dietary practices, body
composition, and energy balance of athletes
– Provide personalized meal and snack plans to
promote achieving short- and long-term goals for
athletic performance and good health
Key Point
• Experienced sports dietitians help athletes
make the connection between plate and
performance. They have advanced
knowledge, skills, and expertise in sports
nutrition.
Standard Nutrition Guidelines
• MyPlate is a food guidance system to help
consumers make better food choices.
• Suggestions may need to be adjusted to
accommodate those who are physically
active more than for 30 minutes most days.
Table 9.2
Standard Nutrition Guidelines
• Dietary Reference Intakes (DRIs)
– The DRI for each nutrient includes the following:
•
•
•
•
Recommended Dietary Allowance (RDA)
Adequate Intake (AI)
Tolerable Upper Level Intake (UL)
Estimated Average Requirement (EAR)
Key Terms
• Recommended Dietary Allowance (RDA):
The average daily nutrient requirement
adequate for meeting the needs of most
healthy people within each life stage and sex.
• Adequate Intake (AI): The average daily
nutrient intake level recommended when a
RDA cannot be established.
(continued)
Key Terms (continued)
• Tolerable Upper Level Intake (UL): The
maximum average daily nutrient level not
associated with any adverse health effects.
Intakes above the UL increase potential risk of
adverse effects.
• Estimated Average Requirement (EAR): The
average daily nutrient intake level considered
sufficient to meet the needs of half of the
healthy population within each life stage and
sex.
Macronutrients
• A macronutrient is a nutrient that is
required in significant amounts in the diet.
• Three important classes of macronutrients:
– Protein
– Carbohydrate
– Fat
(continued)
Macronutrients (continued)
• Protein
– Four of the amino acids can be synthesized by the
human body and are commonly called
“nonessential” amino acids because they do not
need to be consumed in the diet.
– Nine of the amino acids are “essential” because the
body cannot manufacture them and therefore they
must be obtained through the diet.
– Eight are considered conditionally essential.
Table 9.3
Macronutrients
• Protein digestibility
– Calculated by how much of the protein’s nitrogen is
absorbed during digestion and its ability to provide
the amino acids necessary for growth, maintenance,
and repair.
• Protein requirements
– The RDA for protein for adults is 0.8 g/kg (0.36
g/pound) of body weight for both men and women.
(continued)
Macronutrients (continued)
• Protein requirements
– The AMDR for protein in adult men and women is
10% to 35% of total calories.
– Concerns about RDA for protein:
• For bone health, adults may need more than the RDA.
• Consistently high protein intakes may compromise
carbohydrate and fat intake.
Key Point
• Athletes require more than the RDA for
protein to build and repair muscle.
Depending on the sport and the training
program, 1.0 to 1.7 g per kilogram body
weight of protein is recommended.
Macronutrients
• Carbohydrate
– The primary role of carbohydrate in human
physiology is to serve as an energy source.
– Monosaccharides (glucose, fructose, and galactose)
are single-sugar molecules.
– Disaccharides (sucrose, lactose, and maltose) are
composed of two simple sugar units joined together.
– Polysaccharides, also known as complex
carbohydrates, contain up to thousands of glucose
units.
(continued)
Macronutrients (continued)
• Carbohydrate
– Glycemic index
• The GI classifies a food by how high and for how long it
raises blood glucose.
• Foods that are digested quickly and raise blood glucose
(and insulin) rapidly have a high GI.
• Foods that take longer to digest and thus slowly increase
blood glucose (and therefore stimulate less insulin) have a
low GI.
Table 9.5
Adapted, by permission, from Foster-Powell, Holt, and Brand-Miller, 2002.
Macronutrients
• Carbohydrate
– Fiber
• The DRI for fiber is 21 to 29 g/day and 30 to 38 g/day for
young women and men, respectively.
• This level of fiber may be excessive for some aerobic
endurance athletes.
(continued)
Macronutrients (continued)
• Carbohydrate
– Carbohydrate requirements for athletes
• Aerobic endurance athletes who train for long durations
(90 minutes or more daily) should replenish glycogen levels
by consuming maximal levels of carbohydrate, approximately 8 to 10 g/kg of body weight.
• Carbohydrates provide 4 kcal/g.
Key Point
• Athletes adapt to dietary changes in
carbohydrate intake. Though athletes who
regularly consume carbohydrates will use
them as a primary source of energy during
aerobic exercise, consistent intake of a lowcarbohydrate diet will lead to a greater
reliance on fat as a source of fuel.
Macronutrients
• Fat
– Structure and function of lipids
• Fatty acids containing no double bonds are saturated.
• Fatty acids containing one double bond are monounsaturated.
• Fatty acids containing two or more double bonds are
polyunsaturated.
• Fats provide approximately 9 kcal/g.
(continued)
Macronutrients (continued)
• Fat
– Relationship with cholesterol
• High levels of total cholesterol, low-density lipoproteins
(LDL), and triglycerides are associated with increased risk
of heart disease.
• High levels of HDLs protect against heart disease.
• HDLs can be increased by exercise and weight loss.
(continued)
Macronutrients (continued)
• Fat
– It is recommended that 10% or less of calories
consumed come from saturated fats (one-third of
total fat intake).
(continued)
Macronutrients (continued)
• Fat
– Performance
• Intramuscular and circulating fatty acids are potential
energy sources during exercise.
• Fat stores are large and represent a vast fuel source.
• Consistent aerobic training increases the muscle’s capacity
to use fatty acids as fuel.
• When the intensity of exercise increases, there is a gradual
shift from fat to carbohydrate as the preferred source of
fuel.
Key Point
• The human body has a sufficient amount of
fat to fuel long training sessions or
competition.
Vitamins
• Vitamins are organic substances (i.e.,
containing carbon atoms) that cannot be
synthesized by the body.
• They are needed in very small amounts and
perform specific metabolic functions.
Minerals
• Minerals are required for a wide variety of
metabolic functions.
• For athletes, minerals are important for
bone health, oxygen-carrying capacity, and
fluid and electrolyte balance.
Minerals
• Iron
– Is a constituent of hemoglobin and myoglobin; plays a
role in oxygen transport and utilization of energy
– Iron deficiency is the most prevalent nutrition
deficiency in the world
– Increased risk of iron deficiency
•
•
•
•
Women of childbearing age
Teenage girls
Pregnant women
Infants and toddlers
(continued)
Minerals (continued)
• Calcium
– Athletes who consume low-calcium diets may be at
risk for osteopenia and osteoporosis (deterioration of
bone tissue leading to increased bone fragility and
risk of fracture).
Fluid and Electrolytes
• Fluid balance
– Water is the largest component of the body,
representing from 45% to 75% of a person’s body
weight.
– The AI for water is 3.7 and 2.7 L/day for men and
women, respectively.
(continued)
Fluid and Electrolytes (continued)
• Preventing dehydration
– Athletes should try to prevent water weight losses
exceeding 2% of body weight.
– Each pound lost during practice represents 16
ounces of fluid.
Key Point
• A very wide range of fluid losses, in the
form of sweat, exists among athletes.
Therefore, each athlete should develop an
individualized hydration plan.
Fluid and Electrolytes
• Electrolytes
– The major electrolytes lost in sweat are sodium
chloride, and, to a lesser extent, potassium.
– Hyponatremia can develop in those who exercise
intensely and hydrate with only water, causing blood
sodium levels to become diluted (<125 mmol/L).
Key Point
• Athletes who exercise intensely or for hours
and hydrate excessively with only water or a
no- or low-sodium beverage may dilute their
blood sodium to dangerously low levels.
Fluid and Electrolytes
• Fluid intake guidelines
– Start exercise in a hydrated state:
• Prehydrate, if necessary, several hours before exercise to
allow for fluid absorption and urine output.
(continued)
Fluid and Electrolytes (continued)
• Fluid intake guidelines
– Avoid dehydration during exercise:
• Children: Drink 5 ounces of cold water or a flavored, salted
beverage every 20 minutes.
• Adolescents: Drink 9 ounces of cold water or a flavored,
salted beverage every 20 minutes.
• Adults: Follow an individualized hydration program. During
prolonged hot weather activity, consume a sports drink with
20 to 30 mEq of sodium/L, 2 to 5 mEq of potassium/L, and
5% to 10% carbohydrate.
(continued)
Fluid and Electrolytes (continued)
• Fluid intake guidelines
– Rehydrate before the next training session:
• Athletes should consume 1.5 L of water for every kilogram
of body weight lost.