Nutrition Basics

• A nutrient is a biochemical substance that is obtained from food
• Nutrients are used by the body for growth, maintenance, and repair
• Essential nutrients cannot be made by the body, or not in sufficient quantities and therefore must be obtained from an outside source
• Non-essential nutrients are made by the body.
• A kilocalorie (KCAL) measures the amount of energy in food
• KCALs are used by the body to work and generate heat
• The common practice is to use "calorie" to mean the same thing as a KCAL
• Nutrient density refers to the nutrients a food provides relative to the calories it provides
• Organic compounds contain carbon-carbon or carbon-hydrogen bonds
• Examples of organic compounds are carbohydrates, lipids, protein, and vitamins
• Inorganic compounds do not have carbon bonds
• Examples of inorganic compounds are minerals and water
• Current Nutrient and Energy Standards include Dietary Reference Intakes (DRI)
• DRIs have replaced the Recommended Dietary Allowances (RDA)
• DRIs include Estimated Average Requirement (EAR), Tolerable Upper Intake Level (UL), and Adequate Intake (AI)

Dietary Reference Intakes (DRI)

• Estimated Average Requirement (EAR) is the estimated average requirement level to meet 50% of people
• Adequate Intake (AI) is used when there is not enough data to set an EAR
• AI is used for infants and other age groups for calcium, vitamin D, fluoride, pantothenic acid, biotin, and choline
• Daily Values (DV) are reference values developed specifically for use on food labels
• Recommended Dietary Allowances (RDA) are designed to cover the needs of healthy people.

Digestion

• The gastrointestinal tract is part of the digestive system
• The gastrointestinal tract is 30 feet long
• The gastrointestinal tract includes the mouth, esophagus, stomach, small intestine, and large intestine (colon)
• Mastication occurs in the mouth, where salivary amylase breaks down starches
• The esophagus allows food to pass from the mouth to the stomach through the diaphragm
• The stomach functions as a holding tank, secreting hydrochloric acid (HCL), enzymes, and fluid
• The stomach also secretes intrinsic factor, which attaches to vitamin B12, facilitating its absorption in the small intestine
• The small intestine is 10 feet long and has an absorptive surface equal to 1/4 of a football field
• The small intestine is where digestion of carbohydrates and protein is completed, and lipids are digested
• The small intestine is the main site for nutrient absorption
• Its lining consists of villi and microvilli

Sections of the Small Intestine

• The duodenum is the top portion of the small intestine
• Sodium bicarbonate and bile are secreted in the duodenum via the common bile duct
• The jejunum is the first 2/5ths of the small intestine, beyond the duodenum
• The ileum is the last segment of the small intestine
• The large intestine is 5 feet long
• Water, some minerals, and undigested residues pass into the large intestine
• Then, water, electrolytes, and bile salts are absorbed

Accessory Organs

• Accessory organs involved with digestion: liver, gallbladder, and pancreas

Mechanical Digestion

• Mechanical digestion involves the actions of the teeth, tongue, and muscles of mastication
• Saliva lubricates food for swallowing
• The epiglottis closes the airway for swallowing
• A bolus is a portion of food that is swallowed and enters the esophagus
• Peristalsis is involuntary wavelike contractions that move food through the alimentary canal
• The gastroesophageal sphincter is a muscle between the esophagus and stomach, which closes after a bolus is swallowed to prevent reflux
• Chyme is a semi-liquid mass of partially digested food
• Chyme is mixed with HCl acid and expelled from the stomach into the small intestine
• The pyloric sphincter is a muscle between the stomach and small intestine that regulates the flow of chyme into the small intestine
• The ileocecal valve is a muscle at the junction of the small intestine and colon
• The anus is the last muscle that controls the release of feces

Chemical Digestion

• Chemical digestion involves the breakdown of food through chemical reactions
• Salivary amylase initiates the chemical digestion of starch
• Hydrochloric acid (HCl) is secreted by gastric glands, causing the pH of the stomach to be very acidic
• HCl is needed to prepare minerals to be absorbed in the small intestine
• Pepsinogen is activated to pepsin, which begins the digestion of protein
• Mucin protects the stomach lining from HCl acid
• there is no significant chemical digestion of carbohydrates or lipids in the stomach
• Sodium bicarbonate is secreted by the pancreas to neutralize acidic chyme as it enters the small intestine
• Bile is made in the liver and stored in the gallbladder
• Bile is secreted into the small intestine when fats are mixed with chyme
• Bile is made from cholesterol produced by the liver
• Pancreatic enzymes are secreted in the small intestine to digest carbohydrates (carbohydrases), lipids (lipases), and protein (proteases)

Macronutrients

• Carbohydrates provide 4 calories per gram and are organic
• The RDA for carbohydrates is 45-65% of daily intake
• Carbohydrates are the primary energy source for cells
• Carbohydrates are converted to glucose
• Carbohydrates have a protein-sparing effect
• Normal fasting glucose levels are 80-120 mg/dL
• The liver converts all sugars to glucose
• Glycogen is a storage form of glucose made in the liver

Simple Carbohydrates

• Simple carbohydrates include monosaccharides and disaccharides
• Monosaccharides include glucose, galactose, and fructose
• Fructose is the sweetest of the sugars
• Disaccharides include sucrose (table sugar), lactose (milk sugar), and maltose (plant sugar/ferments alcohol)

Complex Carbohydrates

• Complex carbohydrates are long chains of sugars consisting of polysaccharides
• Polysaccharides include plant starch, glycogen (animal starch), and insulin
• Insulin id produced by the pancreas/stores energy
• Dextran forms a substrate for dental plaque biofilm and makes biofilm sticky

Sugar Alternatives

• Sugar alcohols provide 4 calories per gram
• Sugar alcohols cannot be used with Antabuse (a drug used with alcoholics)
• Sugar alcohols can have a laxative effect
• Limit use of sugar alcohols
• i.e. Sorbitol (non-cariogenic) or Mannitol (non-cariogenic) or Xylitol (anticariogenic)
• Sucralose (Splenda) provides 0 calories per gram and is 600 times sweeter than sucrose
• Sucralose does not affect blood glucose levels or insulin response and can be used in baking
• Aspartame (NutraSweet, Equal) provides 4 calories per gram and contains the amino acids phenylalanine and aspartic acid
• Aspartame should not be used by persons with phenylketonuria (inability to metabolize phenylalanine) and cannot be used in baking
• Acesulfame provides zero calories and is 200 times sweeter than sucrose
• Acesulfame can be used in baking and is used in gum, powdered drink mixes, gelatin puddings, and nondairy creamers
• Saccharin (Sweet'N Low) provides zero calories and is 500 times sweeter than sucrose
• Saccharin is derived from coal-tar compounds, widely used in soft drinks/table sweeteners, and thought to possibly cause cancer

Fibers

• Fibers cannot be digested by human digestive enzymes and are non-cariogenic
• The RDA for fiber in adults is 20-35 grams per day
• The RDA for fiber in children is their age + 5 grams per day
• If fiber is increased, fluids must be increased
• Cellulose provides a fibrous framework for plants, is not digestible, and is a good source of fiber
• Hemicellulose does not easily dissolve in water and is a main constituent of cereals
• Pectin thickens jams and fruit preserves, keeps salad dressing from separating, and is found in vegetables and fruits (citrus/apples)

Water-Soluble Fiber

• Water-soluble fiber is viscous
• Water-soluble fiber slows down GI transit time, provides satiety, delays hunger, lowers cholesterol, and is helpful in glucose control for diabetics
• Sources of water-soluble fiber include fruit, oats, oat bran, barley, and legumes

Insoluble Fiber

• Water-insoluble fiber is dietary/functional
• Water-insoluble fiber provides bulk, promotes regularity, and prevents/treats constipation and speeds up the transit time of the GI tract
• Sources of water-insoluble fiber include vegetables, wheat and rice bran, fruits, nuts, and whole grains

Proteins

• Proteins provide 4 calories per gram
• The daily intake from protein should be 10-35%
• Recommended Daily Allowance (RDA) is 0.8 grams per kg for adults
• Pregnant/lactating women, infants, and children are recommended to have a higher protein intake
• 45 g/day is recommended for women, 56 g/day is recommended for men
• Proteins contribute to new tissue growth, maintenance, and repair
• Proteins contribute to fluid/electrolyte balance
• Proteins make up antibodies, enzymes, and hormones
• Proteins contribute to the transportation of compounds through the body, in and out of cells
• Proteins build DNA/RNA
• Proteins act as neurotransmitters
• Proteins regulate pH (acid/base balance) and maintain the pulp of the tooth
• Protein deficiency can result in crowded/rotated teeth due to inadequate bone growth
• Proteins neutralize acids produced by dental plaque biofilm
• Proteins contribute to blood clotting (fibrin), vision (opsin), and pigments (melanin)
• Proteins provide energy when necessary
• Proteins go through Gluconeogenesis: making glucose from a non-carbohydrate source (protein)

Nitrogen Balance

• Nitrogen balance (N in = N out)
• Positive nitrogen balance (N in > N out) promotes growth, pregnancy, supports infants, children, teens, and patients recovering from illness
• Negative nitrogen balance (N in < N out) proteins are broken down to provide energy and glucose for starving patients, burn patients, patients with infections, or injuries

Protein Quality

• High-quality proteins contain all 9 essential amino acids
• Complete proteins are eggs-animal protein and soy
• Low-quality proteins: incomplete proteins do not contain all the essential amino acids
• Complimentary proteins combine foods that, when eaten in combination, will provide all essential amino acids

Protein-Energy Malnutrition (PEM)

• Kwashiorkor affects children ages 1-3
• With Kwashiorkor Energy intake is adequate but there is inadequate high-quality protein
• Marasmus affects infants-2 years old
• Marasmus results in inadequate energy, severe food deprivation/impaired absorption; wasting
• Starvation is the most extreme form of Marasmus
• Starvation results from a lack of essential nutrients for a long time as seen in eating disorders
• Cachexia results in severe wasting away of muscle/fat
• Cachexia is common in those with AIDS and cancer
• Adult PEM affects alcoholics, bedridden or hospital patients, persons taking medications that decrease appetite and increase metabolism
• Excess protein intake (protein intake > 2 times the RDA) can result in heart disease
• A high protein diet can result in low intake of fruits/vegetables and grains
• Excess protein can possibly increase the risk of cancer due to high intake of animal proteins and additional fat stores
• Excess protein can affect calcium balance leading to increased calcium excretion which leads to osteoporosis
• Excess protein can cause stress to kidneys/liver, ketones/halitosis, and can result in dehydration because water is needed by the kidneys to dilute urea

Vegan and Vegetarian Diets

• Vegan diets exclude all animal products
• Vegan diets may be low in high-quality proteins and may be deficient in vitamins B12, vitamin D3, calcium, iron, and zinc
• Lactovegetarian diets exclude animal products except for dairy products
• Ovovegetarian diets exclude animal products except for eggs
• Lacto-ovovegetarian diets exclude animal products except for dairy products and eggs

Lipids

• Lipids provide 9 calories per gram
• Lipids are an important part of the diet and it is Recommended that lipids are 30% or less of daily intake
• Lipids give foods their aroma, flavor, and texture and provide satiety by slowing the rate of gastric emptying (feeling of fullness)
• Lipids are necessary to carry fat-soluble vitamins A, D, E, and K to the small intestine and aid in absorption
• Lipids are the body's chief form of stored energy (calories)
• Lipids insulate the body and protect organs
• Lipids fuel cellular activities and support protein sparing

Fatty Acids

• Saturated fatty acids :
• are less than 10% are typically solids at room temperature
• Can raise total cholesterol/LDL
• Are present in animal fats, butter , egg yolks ,cocoa butter, whole milk, cheese, chocolate, stick margarine, hydrogenated and tropical oils
• Unsaturated fatty acids
• Monounsaturated fatty acids (oleic acid-10%) :
• Present in Olives, olive oil, canola oil, peanuts, peanut oil, peanut butter, cashews, avocado
• May lower LDL and raise HDL (good fats)
• Polyunsaturated fatty acids (linoleic acid-10%) :
• Liquid in consistency
• Present in Corn, soybean, cottonseed, safflower, sesame sunflower oils, almonds, pecans, walnuts, fish
• May lower total cholesterol/may lower both LDL/HDL's
• Omega-6 fatty acids (linoleic) :
  • Present in Cottonseed, corn, safflower, sunflower oils, and tofu
• Omega-3 fatty acids (linolenic):
  • Present in Fatty fish oils and green leafy vegetables, soybean products (tofu)
• Essential fatty acids (linoleic/linolenic acids) must be obtained from diet
• Nonessential fatty acids can be produced by the body
• Hydrogenation is where hydrogen atoms are added to PUFA’s
• Hydrogenation makes them more saturated and reduces the amount of fat per serving
• Trans-fatty acids occur when oils are hydrogenated, especially when they are partially hydrogenated
• Phospholipids (lecithin) are important for cell membranes and fat digestion in the intestines
• Lipoproteins are produced in the liver which allow cholesterol, triglycerides, and phospholipids to be transported in the bloodstream
• Very Low-Density Lipoprotein (VLDL) gathers cholesterol and become LDL's
• Low-Density Lipoprotein (LDL): "bad guys-lousy” with mostly cholesterol (high fat content)
• High-Density Lipoprotein (HDL): "good guys" are produced by the liver/intestine and contain a high amount of protein
• Cholesterol (Sterols): Less than 300mg/day is needed to make important hormones make bile (emulsifier for digestion)
• Cholesterol is Only found in animal products, the Liver can make what the body needs (high levels raise serum cholesterol levels)

Fat Replacers

• Olestra is made by adding fatty acids to sugar, yields no energy (calories), may lower blood serum cholesterol levels but reduces absorption of vitamin E and may cause diarrhea
• Simplesse is a Whey protein product that may cause allergic reactions in Patients that are allergic to egg or cow's milk

Additional Notes

• Alcohol provides 7 kcal/gram but are considered empty calories
• Hyperlipidemia can cause atherosclerosis , the most common CVD in the US and leading cause of death in the US
• All adults over 20 years old should have a fasting lipoprotein screening every 5 years
• A healthy diet, weight control, increased physical activity, smoking cessation, routine medical check-ups for BP and cholesterol, Consume fish at least twice/ week and Decreased intake of refined/processed carbs can help prevent hyperlipidemia