Nutrition

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Nutrition

• Metabolism of carbohydrates, proteins, lipids

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Nutrition - use of food by organisms

• Energy/material providing nutrients Protein,
  carbohydrate and lipid
• Micronutrients Vitamins and minerals necessary
  for biochemical processes
• Essential fiber Non-digestible polysaccharide
  material, essential for normal functioning of
  animal digestive systems (i.e. colon)

http//wine1.sb.fsu.edu/BCH4053/Lecture33/Lecture3
3.htm
3
Buell/Girard, Chemistry, Prentice Hall, NJ, 1994,
546
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Components of Natural Foods

• Carbohydrates
• Proteins
• Fats
• Vitamins
• Minerals
• Fiber
• Water

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Metabolism

• Sum of all the chemical reactions that convert
  nutrients into energy and complex molecules
  required for living systems
• Digestion - process in which enzymes break
  complex molecules down into smaller molecules
  such as monosaccharides, amino acids, etc

http//wine1.sb.fsu.edu/BCH4053/Lecture32/Lecture3
2.htm
6
Joesten et al, World of Chemistry, 2nd, Saunders,
NJ, 1996, 537
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Carbohydrates

• General formula is (CH2O)n
• Digestion involves breaking long chains of
  polysaccharides into monosacchar-ides

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Digestion of Carbohydrates
Monosaccharides are water soluble, absorbed
through intestines and are carried by blood to
cells where they are oxidized for energy
Tro,472
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Digestion of Carbohydrates

• Enzymes catalyze specific reactions
• Human enzymes can digest starches but not
  cellulose (also called fiber) due to the
  different bonding of rings
• Cow or termite enzymes can digest cellulose but
  not starch

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Starch - all rings have same orientation
Brown et al, Chemistry, 8th, Prentice Hall, NJ,
2000,997-998
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FDA Daily Dietary Recommendations

• 60 of daily caloric intake (250 g of
  polysaccharides)
• 50 g or less of simple sugars (mono- and
  di-saccharides such as table sugar)
• 20-30 g of fiber

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Proteins

• Proteins are polypeptides - long chain polymers
  of amino acids
• Digestion involves breaking the peptide bonds and
  obtaining amino acids
• There are 9 essential amino acids which must come
  from food daily since the body can't synthesize
  them
• Amino acids are water soluble

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Digestion of Proteins
Amino acids are absorbed through walls of
intestines, carried by blood to cells where they
are assembled into proteins needed by body
Tro, 473
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FDA recommends intake of 50 g of complete protein
per day (10 of daily caloric intake). Complete
protein means source contains all 20 amino acids
needed by humans
Tro, 473
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Lipids

• Fats and oils are triglycerides - triple esters
  of glycerol and fatty acids
• Digestion converts esters into their component
  fatty acids and glycerol
• Components absorb through intestinal wall and
  then reassemble
• Non-polar so not soluble in blood
• Carried by lipoproteins to liver

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Tro,475
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Cholesterol

• Cholesterol is another lipid, produced in liver,
  is precursor to sex hormones
• Transported by low density and high density
  lipoproteins (LDL or HDL)
• LDL tends to deposit cholesterol in arteries
  causing heart attack or stroke
• Exercise, and diets low in saturated fats, raise
  HDL and lower LDL

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Cholesterol
Main cause of blocking of arteries leading to
heart attacks and strokes
Tro, 476
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Structure of Lipoprotein - a core of cholesterol
and its esters surrounded by phospho-lipid
mono-layer mem-brane in which proteins are
embedded
Garrett/Grisham,Biochemistry,Saunders, NY,1995,794
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FDA Recommendations

• Fats limited to 30 of caloric intake
• No more than one-third of fats should be
  saturated
• Unsaturated fats should be mostly cis- rather
  than trans-structures (next slide)
• Dietary cholesterol should be below 300 mg/day

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Cis- and Trans- Structures
Cis - Two like groups located on adjacent C
atoms- both above or both below the double bond
Trans - Two like groups located on adjacent C
atoms- one above and one below the double bond
http//www.wpbschoolhouse.btinternet.co.uk/page06/
AlkeneStructure.htm
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Vitamins

• Organic compounds essential in the diet in small
  amounts but have little or no caloric value
• Non-polar or fat soluble are A, D, E, K
• Polar or water soluble are B and C
• Antioxidants are A, C,and E
• Vitamin A comes from carotene(carrots)

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Minerals

• Minerals are inorganic substances that are
  required by a living system to sustain life
• In some cases metal ions needed to make enzymes
  function
• Iron is needed to make hemaglobin which carries
  oxygen
• Usually water soluble

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Metabolism
Anabolism - Assembly of complex molecules,
requires the input of energy
Catabolism - Degradation of complex molecules,
with the release of energy
http//users.rcn.com/jkimball.ma.ultranet/BiologyP
ages/M/Metabolism.html