Lecture Notes-7

2. Appetite: the psychological need to eat. May arise in response to the thought, sight or smell of food even when you do not physically need to eat.

• Reasons for choosing specific foods:

1. Personal preferences

• You like them; they taste good

2. Habit or ethnic tradition

• Familiar; you always eat them

3. Social pressure

• Offered; feel you can’t refuse

4. Availability

• There and ready to eat

5. Convenience

• Too rushed or tired to prepare anything else

6. Economy

• Affordability

7. Emotional needs

• Gratification; makes you feel better for a while

8. Values or beliefs

• Religious tradition; environment; social; ethical, etc.

9. Nutritional value

• They are good for you (nutrients & energy balance)

• Nutrition: the study of nutrients and their effects on the body

• Nutrients: substances obtained from foods and used in the body for growth, maintenance and repair

• Essential Nutrients: those nutrients the body cannot make for itself and, therefore, must be obtained in the diet

• Dietary Guidelines for Americans 2005

• The deficiency diseases of the past (scurvy, rickets) have been replaced by poor nutrition and inactive lifestyles

• Undernutrition: inadequate food intake causing disease or susceptibility to disease

• Example: iron-deficiency anemia

• Overnutrition (overeating): overconsuming food sufficiently to cause disease or susceptibility to disease

• Example: obesity

• Poor nutrition and inactivity (first seven) may cause:

• Heart disease

• Stroke

• Hypertension

• Dyslipidemia (elevated blood fats)

• Type II diabetes

• Overweight & obesity

• Osteoporosis

• Constipation

• Diverticular disease

• Iron deficiency anemia

• Malnutrition

• Some cancers

• Low intake of foods and nutrients in U.S. population:

• 93% don’t get recommended amount of vitamin E

• Women consume only a little over half the recommended amount of calcium

• 44% don’t get enough vitamin A

• 33% fall short on vitamin C

• Iron deficiency-most common trace mineral deficiency

• Men and women 10 grams/day short on fiber

• 54% not enough vitamin B6

• 33% not enough folic acid (B9)

• 63% not enough magnesium

• 75% not enough zinc

• The Six Basic Nutrients:

• Macronutrients (energy nutrients/calories):

• Protein

• Fat

• Carbohydrate

• Micronutrients

• Vitamins

• Minerals

• Water

• Protein

• Recommended intake

• ~15% of calories (10-35% range)

• 0.36 grams per pound body weight (54 gm - 150lb.; 72 gm – 200 lb.)

• Energy-yielding (4 calories per gram)

• Mostly during very long-term exercise or starvation

• Tissues (muscle, bones, cartilage, skin)

• Enzymes

• Hormones

• Antibodies

• Made up of amino acids (C-H-O-N)

• 20 AAs

• 11 body can manufacture

• 9 essential

• All AAs must be available at one time for the body to use protein for tissue building

• The body cannot make partial proteins—only complete ones

Complete Proteins:

• Contain all of the essential AAs

• High-Quality Proteins:

• Contains all essential AAs in proportion to need

• Incomplete Proteins:

• Does not contain all essential AAs in proportion to the body’s needs

• The body cannot make partial proteins—only complete ones—vegans must combine proteins (“protein complementing”)

• Sources of Protein:

• Animal sources of complete, high-quality proteins

• Meat, fish, poultry, eggs, fish, cheese

• Legumes (seed pods that split on two sides when ripe)

• Dried beans, dried peas, dried lentils, peanuts, *soybeans, and *soy products

• Grains

• Oats, rice, barley, cornmeal, whole-grain breads and pastas

• Nuts & Seeds

• Walnuts, cashews, pecans, sunflower seeds, sesame seeds

• Vegetables

• Broccoli and dark, leafy green vegetables

*contains all essential AAs and add’l health benefits

• Excess protein intake can cause:

• Calcium excretion

• Extra nitrogen excreted in the urine, straining kidneys

• Carbohydrate

• Carbohydrates include:

• Simple Carbohydrates (sugars)

• Complex Carbohydrates (starches; fiber)

• Recommended Intake:

• ~45-65% of diet should be carbohydrate

• No more than 10-25% from simple sugars

• The body’s most efficient source of energy

• 4 calories per gram

• Preferred during high-intensity activities

• Carbohydrates should be the primary source of energy because they are a major source of vitamins, minerals, fiber, and other nutrients good for health.

• Most carbohydrates are plant based:

– Grains, vegetables, fruits, legumes

• Simple Carbohydrates (sugars):

– Monosaccharides

• Glucose (the body’s fuel)

• Fructose (fruit sugar)

• Galactose

– Disaccharides

• Sucrose (table sugar)

• Lactose (milk sugar)

• Maltose

– All carbohydrates are broken down in the intestine and converted to glucose in the liver

– Carbohydrates

• Complex Carbohydrates:

– Long chains of glucose units

– Keep blood sugar level stable and help prevent heart disease, some forms of cancer, and other degenerative diseases

– Starch: principal carbohydrate found in plants and vegetables

• Grains, potatoes, fruits, vegetables, legumes

• Most are nutritionally “dense”

• Stored in muscles and liver in limited amounts

– Glycogen: form of carbohydrate found in animals and humans (chains of glucose units)

• Liver

• Muscle

– Carbohydrates

• Fiber:

– Mostly indigestible by humans-no calories

– Holds water – provides intestinal bulk

– Prevents infection of the appendix, helps control blood-cholesterol levels, reduces heart disease, diabetes, cancer and obesity risk

– Makes stools softer—preventing constipation and other ills

– Sources: plant foods, especially with their skins intact

• Substitute with brown rice, whole wheat products, 100% bran breakfast cereals, whole grain pasta, beans, unpeeled fruits and vegetables

– Recommendation: 30 gms of fiber per day (typical =15 gms)

• Carbohydrates

• Sugar Substitutes:

– Sugar alcohols

• Maltilol, sorbitol, xylitol, mannitol

• Bacteria do not metabolize as easily—do not contribute to tooth decay

• As many calories as sucrose, even if says sugar free

– Artificial Sweeteners

• Calorie-free—no calories

• Saccharine (warning labels), aspartame

• Fats

• No more than 30% of calories should come from fat (with no more than 10% saturated/trans fats)

• Present in triglyceride form

– Glycerol—FA—FA—FA Lypolysis Glycerol FFA FFA FFA

• Essential functions:

– Concentrated energy source – 9 calories per gram

– Transport fat-soluble vitamins

– Insulate & protect body organs

– Regulate hormones

– Contribute to growth

– Part of cell wall, nerve tissue

– Important for healthy skin

– Texture and flavor to foods

– Provide satiety (feeling of fullness)

• Too much fat can be harmful:

– Obesity

– High blood pressure

– Stroke

– Heart disease

– Diabetes

– Some forms of cancer

• Types of Fats:

– Saturated

– Monounsaturated

– Polyunsaturated

– Plus:

– Trans Fats

– Cholesterol

• Saturated Fat

• Solid at room temperature

• Raises level of LDL cholesterol and linked to heart disease and other degenerative diseases

• Animal products (meat), butter, lard

– Monounsaturated Fat

• Liquid at room temperature

• Peanuts, cashews, olives, avocados, olive oil, peanut oil, cottonseed oil, canola oil

• Polyunsaturated Fat

– Liquid at room temperature

– Found in most vegetable oils, fish, margarine, walnuts, almonds, pecans, corn oil, sunflower oil, sesame oil, soybean oil

• Fats

• Trans Fats

– Some monounsaturated fats and polyunsaturated fats can undergo hydrogenation during manufacturing, creating trans fats

– Longer shelf life

– Found in shortening, margarine, some crackers, and some nut butters

– May carry as much risk as eating saturated fat

• Cholesterol:

– A type of fat

– Some beneficial roles: digestion, membranes protecting nerve fibers, vitamin D, sex hormones

– Too much in bloodstream – high risk of developing heart disease

– High fat diet causes increased cholesterol (just as important as cholesterol intake)

• Vitamins:

– Zero calories

– Organic

– Smaller quantities

– Powerful nutrients…deficiencies can be deadly

• Cure diseases caused by deficiencies in the vitamin itself

– Can overdose

– Eating a variety of foods beneficial

• Two Categories of Vitamins:

– Fat-soluble Vitamins:

• A D E K

• Stored in fat cells

• Can be toxic faster than water-soluble vitamins

• Deficiencies less common than water-soluble vits

– Water-soluble Vitamins:

• C and B-Complex

• Dissolve readily in water & excreted in urine

• harder to be toxic

• Deficiencies occur more quickly

• Vitamins

• Vitamins C, E, and beta carotene (vitamin A precursor) function as antioxidants.

– prevent oxygen free-radicals from combining with other substances and causing damage

– Protects cell membranes and DNA from damage—believed to prevent heart disease, cancer, and emphysema

• Minerals:

– Zero calories

– Smaller quantities

– Mostly facilitators of body processes

– Inorganic

– Major minerals (>5 grams) & Trace minerals (<5 grams)

– Extremely toxic if large amounts

• Calcium and Iron deficiencies common

– Calcium:

• osteoporosis

– Iron: iron deficiency anemia

• Too much iron can cause infections, tissue damage, liver damage

• Consult physician before taking iron supplementation

• Water

– Zero calories

– Essential for life

– Major component of blood

– Helps body use other nutrients

– Aids in digesting food

– Electrolyte balance

– Lubricates joints

– Temperature regulation

• Eight to ten 8-ounce glasses of water a day

– More if necessary

• Cannot always rely on thirst

– Drink before necessary

• Color of urine is an indicator

• 1 ½ hours to effect tissues (muscle)

• Phytochemicals / Phytonutrients

• Phytochemicals (phytonutrients), phytomedicinals, and antioxidants are the essential nutrients of the 21^st century and may have dramatic effects on future guidelines.

• Nutrition Acronyms

• DRI (Daily Reference Intakes):

– New “Umbrella” Term. Amounts of nutrients that best support health…4 values:

– RDA (Recommended Dietary Allowance):

• Nutrient intake sufficient to meet needs of nearly all healthy people in age/gender group. Considered generous. Aim for this intake.

– EAR (Estimated Average Requirement)

• Using population average, amount necessary to maintain a specific body function.

– AI (Adequate Intake):

• Used when evidence is insufficient to set an RDA. Aim for this intake when RDA is not set.

– TUIL (Tolerable Upper Intake Level):

• Safe, upper limit of a nutrient.

• EER (Estimated Energy Requirement):

– Dietary “energy” intake to maintain energy balance.

• DV (Daily Value):

– Condensed system used on food labels. Based on a 2000 calorie diet--% of nutrient’s daily recommended intake.

• Daily Values and Food Labels

• FDA requires all nutrients in a food to be listed on a label

• Every label must include:

– Common name of product

– Name & address of manufacturer, distributor, or packer

– Net contents of package (count, measure, or weight)

– Ingredients listed in descending order, with most plentiful first

– If the product makes nutritional claims, the product must contain ”Nutritional Information” on label:

– Serving or portion size

– Servings per container

– Calories per serving

– Carbohydrates (grams) per serving

– Fats (grams) per serving

– Vitamins, minerals, and proteins (% RDA) per serving

– Amounts of 8 “indicator nutrients” – protein, vitamin A, niacin, thiamin, riboflavin, vitamin C, calcium, and iron

• Consumer Safety - Foods

• Primary Concerns:

– Additives

– Irradiation

– Food-borne illnesses

• Food Additives

– Chemical agents added to processed foods to preserve, improve appearance, enhance flavor

– Antioxidants

• BA & BHT – keep oils & fats from becoming rancid

– Emulsifiers

• suspend flavor oils throughout the product improving flavor & appearance

– Preservatives

• Inhibit bacterial growth for longer shelf life

• Radiation

– Improve quality of fresh & processed foods

– Gamma Radiation increases shelf life and kills microorganisms that might have contaminated

– Does not make food radioactive

– FDA approved

• Food-borne Illnesses

– Food contaminated with bacteria or parasites

– Examples:

• Meat: E,coli bacteria (5%)

• Poultry: Salmonella bacteria (25%)

• Refrigeration doesn’t kill—must cook thoroughly

– Signs & Symptoms:

• nausea, vomiting, abdominal pain, bloating, gas diarrhea

• Typically 5-8 hours after eating, but sometimes 30 minutes-several weeks later

• 2/3 restaurants; 1/3 home

• To Protect Yourself from Food-Borne Illnesses:

– Check expiration dates on all meat, poultry, fish

• Eat in next few days or freeze

– Refrigerate perishable foods

• Unfrozen food no longer than 3 days in refrigerator

• Refrigerator 40 degrees or less

– Never thaw foods on the counter

– Wash utensils & cutting boards thoroughly

– Sanitize cutting boards at least once per week

– Avoid eating raw eggs

– Do not share utensils & cutting boards between raw meats and raw vegetables

– Cook all meat, poultry, and fish thoroughly

• Pork & chicken juices run clear; no pink

• Meat cooked at least medium rare—more caution with ground meat with no traces of pink

– Do not leave cooked foods standing at room temperature for longer than 2 hours

– Never place cooked meat on the same plate that held the raw meat

• How to Choose Nutritious Foods

• Need at least 40 vitamins & Minerals, Fiber , Phyotochemicals, Energy, etc.

• Eat a VARIETY of foods in MODERATION

• USDA Food Guide:

– Can help design an adequate and balanced diet

– Defines major food groups and suggests portions from each group

– Conveys key nutrients from each food group

– Most nutrient-dense foods are recommended

• Help to control overweight and obesity

• MyPyramid

– Educational tool to illustrate Dietary Guidelines and USDA Food Guide

– Can create individualized diet plan

• Nutrient Supplements

• Billions of dollars spent each year

• No supplement can give you all the nutrients you get from food

– Example: phytochemicals

• Times when nutrient supplements are useful

– Deficiency

– Energy intake below 1500 calories/day

– If you know your diet will temporarily not be good

• Follow directions for supplement use as provided by your health care provider

• Change your diet before relying on a nutrient supplement