Nutrition

• Nutrition:

  • study of how living organism obtain and utilize nutrients needed to grow and sustain life
• Nutrients

  • includes most biomolecules, vitamins, and minerals
  • required for synthesis of new molecules
  • required for energy, maintenance, growth, and repair
• Macronutrients:

  • must be consumed in relatively large quantities
  • needed in daily amounts
  • carbohydrates, lipids, proteins
• Micronutrients

  • must be consumed in relatively small quantities
  • vitamins and minerals
• Essential Nutrients

  • must be obtain and absorbed via digestive system from diet
• Nonessential Nutrients

  • provided by biochemical processes of body
  • not required in diet
• Recommended daily allowance (RDA)

  • amount of each nutrient that must be obtained each day
• macronutrients provide fuel (energy) for ATP, this energy is measured in calories
• calorie

  • the amount of heat required to raise the temperature of 1g of water by 1°C
• kilocalorie

  • 1 Kcal= 1000 calories
• Carbohydrates:

  • monosaccharides, disaccharides, polysaccharides
  • described as sugars, starch, and fibers
• Sugars:

  • includes monosaccharides (glucose, fructose, galactose)
  • includes disaccharides (sucrose, lactose, maltose
  • other sugars include (dextrose, brown sugar, honey, molasses)
• Starch

  • polysaccharide polymer of glucose molecules found in certain foods
  • grains, beans, peas
  • refined starches sometime added as thickeners, stabilizers
  • cornstarch
• Fibers:

  • includes fibrous molecules of both plants and animals
  • cannot be chemically digested and absorbed by GI tract
  • lentils, peas, beans, whole grains, oatmeal, berries, nuts
• sugars and starch are usually converted to glucose

  • primary energy supplying nutrient
  • glucose is not considered essential because it can be synthesized via gluconeogenesis
• Purpose of Fibers

  • adds bulk
  • stimulates peristalsis
  • "keeps you regular"
• Lipids:

  • triglycerides
  • phospholipids
  • steroids
  • Eicosanoids
• Triglycerides are composed of glycerol and fatty acids
• 3 categories of fatty acids

  1. saturated
  2. unsaturated
  3. polysaturated
• Saturated fatty acids

  • have no double bond
  • solid at room temperature
  • fat in meat, milk, cheese, coconut oil, palm oil
• Unsaturated fatty Acids

  • one double bond
  • sources are liquid at room temperature
  • Nuts, canola oil, olive oil, sunflower oil
• Polyunsaturated fatty acids

  • two or more double bonds
  • sources are liquid at room temperature
  • soybean oil, corn oil, safflower oil
• Cholesterol

  • required component of the plasma membrane
  • precursor hormone for steroid hormones, bile salts, vitamin D
  • comes from diet of metabolic pathway in liver
• Proteins: most structurally and functionally diverse molecules

  • needed to replace worn out protein structures
  • amount needed depends on age and sex
  • 8 amino acids are essential, other 12 can be synthesized by the body
• Complete proteins:

  • contain all essential amino acids
  • generally animal proteins
• Incomplete proteins

  • do not contain all essential amino acids
  • generally plant proteins
• Vegetarians: does not eat meat, poultry, fish

  • lacto-ovo vegetarians: eat milk, eggs, and cheese
  • vegans: eat no animal products
• Nitrogen Balance

  • proteins are a source of nitrogen
  • nitrogen is needed to synthesize nitrogen containing molecules (DNA, RNA, porphyrin)
• positive nitrogen balance

  • absorbing more nitrogen that secreted
  • happens during growth, pregnancy, recovering from injury
• Negative nitrogen balance

  • more nitrogen excreted than absorbed
  • during blood loss, malnutrition, can be fatal
• Vitamins:

  • organic molecules required for normal metabolism
  • can be water or fat soluble
  • can be essential or non essential
• Water soluble vitamins

  • dissolve in water
  • B vitamins serve as coenzymes
  • Vitamin C is required for collagen synthesis; antioxidant
  • easily absorbed into blood from GI tract
  • excess is excreted in urine
• Fat soluble vitamins

  • dissolved in fat
  • Vitamins A, D, E, K
  • absorbed from GI tract w/n micelles
  • excess stored in fat
  • may become toxic if taken in excess
• Vitamin A

  • precursor of visual pigment retinal
• Vitamin D

  • forms calcitriol; increases calcium absorption from GI tract
• Vitamin E

  • stabilizes and prevents damage to cell membranes
• Vitamin K

  • required for synthesis of blood clotting proteins
• Essential Vitamins

  • necessary from diet
  • deficiency if intake or absorption is impaired
  • example is vitamin C and A
• Non essential vitamins

  • cofactors body produces and recycles as needed
  • NADH, FADH2
• Minerals

  • inorganic ions obtained from diet
  • required in daily amounts