Chemistry 106
University of Nebraska – Lincoln
Spring 2009
25 March, 2009
NUTRIENTS
•
•
•
•
•
Carbohydrates
Lipids
Proteins
Vitamins
Minerals
Proteins
• Why eat proteins?
– To provide amino acids for new protein synthesis
– As a source of nitrogen and sulfur
• Most abundant macromolecules (large
molecules) in the cell
• Excess amino acids cannot be stored in the
body (nitrogen is converted to ammonia and
excreted as urea)
• However, protein deficiency is very rare in
the U.S.
Proteins
• Biological catalysts (enzymes)
• Antibodies that fight antigens (bacteria and viruses)
• Transport molecules and ions
• Regulate cell function (hormone)
• Provide structural support and mechanical strength
• Necessary for all forms of movement
• Sources of amino acids for growth
Essential Amino AcidsKNOW F OR TEST:
Leucine
Isoleucine
Lycine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
The high-quality protein of eggs contains essential amino
acids in nearly the same ratios found in human protein.
Protein Quality
Grams of the essential amino acids per 100 g of hens’ eggs
compared to that of cornmeal (approximate values).
Dates, lima beans, cornmeal, and peanuts represent plant foods that are
deficient
in one or more essential amino acids – these are considered low-quality
protein.
-High quality protein have high levels of essential amino acids, low quality
proteins do not…
Know for test
-More essential amino acids from animal protein
Proteins
In general, plants are relatively poor sources of protein.
Animal foods (beef, poultry, seafood, dairy products, eggs)
provide our best source for protein.
Complementary proteins can be obtained by a varied diet.
(These are proteins that individually are incomplete or low
quality but when taken together provide the amount and
ratios of protein required)- choose foods so that each one
has high values of different amino acids, so that a
proficient amount of each amino acid is eaten (for
vegetarians)
Macronutrients
• Macronutrients include carbohydrates, proteins, and fats and oils
• They make a major portion of food we eat in volume and weight
Micronutrients
•Vitamins and minerals (and additives?)
• not normally converted into energy_• make up very small mass of body (except calcium and
phosphorus)
Minerals
• Nutritionally
important elements except C, O, H, N, S
• Not synthesized by the body
• Used by body in ionic form
• Toxic if ingested in excess
•Plants provide a good source of minerals
Major Minerals
• Calcium (1.5-2% of body weight)
– Most abundant mineral in body
– 99% in body found in bones and teeth
– Required for nerve transmission,
muscle contraction, and blood
clotting
Major Minerals
• Phosphorous (1-1.5% of body weight)
– Required for optimum Ca packing (increasing
density) in bones and teeth– Used in DNA and RNA
Major Minerals
• Sodium, potassium, chloride
– Maintenance of salt levels in body fluids
(required by many enzymes)
– Nerve Transmission: intercellular (outside of
the cell) sodium and intracellular potassium
(inside the cell itself)
– Chloride used in HCl as stomach acid
Major Minerals
• Magnesium
– Found in teeth and bones, helps protein
formation, and intercellular electrical
transmission promoter
Minor Minerals (trace elements)
• Similar
to vitamins in that
• required in small amounts (<100 mg/day)
• food usually only contains a small amount
• Most used in enzymes and hormones
• Exact function of many trace elements remains
unknown
Minor Minerals (trace elements)
• Iron
• contrary to many trace elements its
function is well known
• used in the protein hemoglobin
• binds to and transports oxygen to cells
• Anemia – iron deficiency (reduced
oxygen)
• too much iron can cause cirrhosis of the
liver
Minor Minerals (trace elements)
• Iodine
• concentrated in thyroid gland
• required in the hormone thyroxine which
regulates metabolism
• too much or too little can lead to Goiter
(swelling of thyroid gland)
Minor Minerals (trace elements)
• Fluorine
• hardens enamel of teeth
• some communities add fluorine to drinking water
• many toothpastes contain sodium fluoride
• Zinc
• involved with growth via enzyme function
• healing of wounds
• Copper
• critical component of some enzymes
• interacts with iron in hemoglobin
• Chromium
• glucose metabolism
• efficient use of insulin
Vitamins
• A group of naturally occurring organic compounds
found in the diet and essential to good health
• Not used for energy or body muscle/bone
• “vitamin” originally from the phrase “vital amine”
• minerals are from the soil, vitamins are from plants
and other animals (produced from plants and animals)
• like minerals they are required in small amounts
Vitamins
• Categories of vitamins
•Fat-soluble: soluble in non-polar solvents (fats,
oils, hydrocarbons, etc.)
• Vitamin A, D, E, K
• Water soluble: soluble in water and other polar
solvents
• B vitamins and vitamin C
Vitamins
Differences between fat and water soluble vitamins
– Many water soluble vitamins have several hydroxyl
groups (OH-) – allows hydrogen bonding with water.
– Fat soluble vitamins need not be taken daily: stored in
fat and liver tissue (can build up to toxic levels)
– Water soluble vitamins (generally) are not stored so
must be consumed frequently & in small quantities.
Fat Soluble Vitamins
Water Soluble Vitamins
Vitamin A
• Chemical name:
Retinol
• Characteristics
• Fat-soluble vitamin – accumulates in fats and liver
• important for skin, eyes, mucous membranes
• food sources – meat (liver)
(not found in plants)
• overdose symptoms
• headache, dizziness, nausea, death
• birth defects
• orange/yellow vegetables contain no retinol but do contain
b-carotene which is easily converted to retinol
• eating excess “carrots” will not give overdose of retinol but may
impart an orange/yellow color to the skin
b-carotene molecule
***be able to recognize both for test!!!!
2 retinol molecues