Chapter 3 -- Nutrition

1. Introduction

Nutrition studies the relationship of foods to optimal health and performance

Nutrients should be obtained from a variety of foods!

Too little or too much can cause health problems.

Nutrition plays a crucial role in the development of chronic diseases

Obesity, diabetes, and osteoporosis have been linked with nutrition

Guidelines for a healthful diet:

1. Eat a variety of foods
2. Avoid fat, saturated fat, and cholesterol
3. Eat foods with adequate starch and fiber
4. Avoid too much sugar & sodium
5. Adequate intake of calcium
6. Main proper bodyweight
7. Reduce/Avoid alcohol

2. Nutrients

Essential nutrients required by the human body are:

1. Carbohydrates
2. Fats
3. Protein
4. Vitamins
5. Minerals
6. Water

Carbos, Fats, and Protein are fuel nutrients- Substances the body uses for energy

Vitamins, minerals, and water have no caloric value but are necessary

Macronutrients- Those which large amounts are need daily (Carbos, Fats, Protein, Water)

Micronutrients- Those needed in small amounts (Vitamins, Minerals)

High nutrient density- foods that contain few calories which are packed with nutrients.

Low nutrient density- Foods that contain many calories which have few nutrients.

Calorie- Unit of measurement indicating energy value of food or physical activity

Carbohydrates

Major source of calories for the body to produce energy

Helps digest and regulate fat and metabolize protein

Each gram provides body with 4 calories

Major sources: Breads, cereals, fruits, vegetables

Classifications:

1. Simple carbohydrates (formed with simple or double sugar units)

Monosaccharides- Simplest sugars

Glucose- found in food and produced by the body

Fructose- found in fruits and honey

Galactose- Produced from milk sugar

[Fructose and Galactose are converted to glucose in the body which is a source of energy or stored as glycogen]

Glycogen- long chain of glucose molecules hooked together.

Excess glucose is converted to and stored as FAT!

Disaccharides- formed by linkage of two monosaccharides

3 most common disaccharides:

Sucrose (table sugar) [glucose + fructose]

Lactose [glucose + galactose]

Maltose [glucose + glucose]

2. Complex Carbohydrates- formed when 3 or more simple sugar molecules bind together

Examples of complex carbohydrates:

Starch- the storage form of glucose in plants

Found in grains, seeds, corn, nuts, potatoes

Grains = richest source / should supply most of the energy in the diet

Once eaten, starch is converted to glucose for use by the body

Dextrins- formed from the breakdown of starch molecules exposed to dry heat (baking bread)

Glycogen- an animal polysaccharide from glucose (not found in plants)

Stored in liver & muscles

When energy is needed, enzymes in the muscle and liver break down glycogen into glucose

Dietary Fiber

Complex carbohydrate made of plant material (not digested by the human body)

Exists in leaves, skins, roots, and seeds

• Sources of fiber In diets are cereals, breads, fruits, and vegetables
• Common types of fiber:

Cellulose & Hemicellulose found in plant cell walls

Pectins, found in fruits

Gums found in plant foods

Fiber helps with digestion and the removal of waist

Fiber is thought to bind with carcinogens to dilute them

Fiber may reduce the risk for coronary heart disease because:

Saturated fats often replace fiber in the diet

Specific water-soluble fibers seem to bind with cholesterol in the intestines preventing absorption

Recommended amount of dietary fiber is 20-30 grams/day (FDA 20-30, AMA 25-30)

Too much fiber can produce loss of calcium, phosphorus, and Iron and can cause intestinal discomfort

Fats (Most concentrated source of energy -- 9 cal./ gram)

Used as stored energy and insulates and protects the body

• Supply essential fatty acids and carry fat-soluble vitamins (A,D,E,K)
• Common sources: Milk/Dairy, Meats

Three groups of fats:

• Simple Fats (consists of a glyceride molecule linked to a fatty acid)

• Monoglycerides - One fatty acid
• Diglycerides - Two fatty acids
• Triglycerides - Three fatty acids

Fats also dived into saturated and unsaturated Fats

Saturated fats

• Of animal origin
• Usually do not melt at room temp.

Unsaturated fats

• Found in plant products
• Usually liquid at room temp.
• Classified into Monounsaturated and Polyunsaturated

• Saturated fats raise blood cholesterol levels
• Polyunsaturated fats and Monounsaturates lower it
• Polyunsaturated fats MAY cause a reduction of HDL
• Omega 3 fatty acids may lower risk factor for coronary heart disease

• Found in fresh or frozen fish: Mackerel, Herring, Tuna, Salmon, Lake trout
• Canning process eliminates most Omega-3 oils
• People with health problems or family history of health problems should check with a physician before consuming fish oil

Compound Fats- Combination of simple fats and other chemicals

• Phospholipids
• Glucolipids
• Lipoproteins- transport fat in the blood -- Major forms:

  HDL (high density lipoproteins)- High levels are associated with lower risk of heart disease

  LDL (low density lipoproteins)- Linked to increased risk of heart disease

  VLDL (very low density lipoproteins)- Higher risk of heart disease

• Derived Fats- Combination of simple and compound fats

Protein- Main substances the body uses to build and repair tissue (4 cal./gram)

• Can be used as a source of energy if there is not enough carbos available
• Main source: Meats, Dairy, Alternates
• Excess protein is converted to glucose or fat
• Amino Acids- Basic building blocks of protein (human body uses 20 amino acids)
• Essential (9)- The body cannot produce them
• Non-essential- Can be manufactured by the body
• Complete proteins- Those which contain all the essential amino acids (usually in animal sources)
• Incomplete proteins- those which do not contain all the essential amino acids (usually plant sources)
• Protein deficiency is not a problem in the typical American diet
• Can be of concern in vegetarian diets -- 4 basic types of vegetarians:
  • Vegans- Eat no animal products at all
  • Ovovegetarians- Allow eggs in the diet
  • Lactovegetarians- Eat foods from the milk group
  • Ovelactovegetarians- include egg and milk products
• Too much animal protein can cause serious health problems
• Protein foods from animal sources are often high in fats, saturated fats, and cholesterol

Vitamins- Organic substances necessary for normal bodily metabolism, growth, and development

• Function as antioxidants, coenzymes, and hormones
• Antioxidants- Prevent oxygen from combining with other substances and play role in the prevention of disease
• Oxygen helps convert carbohydrates and fats to energy during metabolism
• Small amount of this oxygen ends up as oxygen free radicals- unstable forms
• Has an unpaired electron which attracts and pairs with an electron from another molecule making it unstable etc.
• Antioxidants help stabilize free radicals
• Vitamins are classified into two groups:
• Fat-soluble (A, D, E, K)- Stored in the body
• Water-soluble (B-Complex, C)- Not stored in the body
• Vitamins should be obtained from a well balanced diet.

Minerals- Inorganic elements found in the body an in food

• Contained in all cells (especially the hard parts of the body: bones, teeth, nails)
• Most common minerals: Calcium, Iron, Sodium

Water

• About 70% of total body weight is water (most important nutrient)
  • Is involved in almost every vital process
  • Water is contained primarily in liquid foods, fruits, and vegetables
  • Everyone should drink about 8 glasses of fluids per day

Energy Production (ATP)

• ATP (Adenosine Tri-phosphate)- Energy-rich compound food is converted into (must be recycled continuously to sustain life).
  • Can be recycled in three ways:
  • ATP & ATP-CP system- Used for short duration, all-out activities (up to 10 secs.)

• Anaerobic system- used during high intense anaerobic activities (10-180 secs.)

• Aerobic System- The production of energy during low-intense, sustained activities.

Balancing the Diet

Of total calories about:

• 58% from carbohydrates (48% - Complex, 10% - Sugar)
• Less than 30% fats (No more than 10% - sat.)
• 12% - Protein
• Diet must include essential vitamins, minerals, and water

RDI (Reference Daily Intakes) - were created for protein, vitamins, and minerals

DRV (Daily Reference Values) - Provide information based on a 2,000 calorie diet.

To achieve a balanced diet, one should eat a variety of foods and reduce fats and sweets

Nutrient Supplementation

• Water-soluble vitamins can NOT be stored in the body like fat soluble vitamins (the body excretes excessive amounts).
• In certain situations, people may need supplementation (pregnant women, Women with heavy menstrual flow, Vegetarians)
• For most people, there is no need for supplementation (with a balanced diet).

Nutrition for athletes

• Two main fuels supply energy for physical activity:

Glucose- Comes from foods high in carbohydrates

Fat- supply most of the energy at rest.

• During exercise, the body uses both fat and glucose
• Most athletes do NOT require special supplementation

Amino Acid supplements (Protein)

• Protein can be easily consumed in sufficient amounts through your diet.
• Excess protein not used is converted to fat
• Muscle OVERLOAD (through training) builds muscles --- NOT supplementation!

Special Nutrition considerations for women

• Bone Health
• Osteoporosis- softening, deterioration, or loss of body bone
  • Women are especially susceptible after menopause
  • Physical activity, adequate calcium, and estrogen can reduce the risk of osteoporosis
  • (RDA for calcium is 800-1200 mg/day)
  • vitamin D may be needed to promote calcium absorption
  • A high protein diet is believed to promote calcium loss
  • Weight-bearing exercises tone muscles AND strengthen bones!

• Iron Deficiency (RDA = 15 mg/day for women & 10 mg/day for men)
  • Iron is the element in hemoglobin which carries oxygen in the blood
  • Without sufficient Iron, anemia can result
  • Physically active women may need more Iron
  • Most people get adequate amounts of iron in the diet by eating foods such as Beans, Peas, Leafy vegetables (skillet???)

Three factors that most improve longevity and quality of life:

1. Proper nutrition
2. A sound exercise program
3. Quitting smoking

If parents adopt a healthy diet, children will most likely follow

The motivating factor to change eating habits seems to be a major health breakdown

"An ounce of prevention is worth a pound of cure"

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