Download The Vitamins Chapter 7 Objectives of Chapter Differentiate b/t fat

The Vitamins Chapter 7
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Objectives of Chapter
Differentiate b/t fat soluble & water soluble vitamins
Know primary role (s) of each vitamin
Know primary sources for each vitamin
o identify your sources
Review concerns of deficiency & toxicity for each vitamin
*Understand antioxidants
Vitamins
Essential, non-caloric, organic nutrient needed in small amounts for vital functions in body
o small amounts needed is no indication of importance
“Precursors or Pro-vitamins” form found in food
o once inside body, transformed chemically to “active” form
 i.e. precursor for vitamin A is beta-caratine
 vitamin A is only found in animal products, but its precursor beta-carotine is found in
vegetables & fruits
Vitamins
Discovered at beginning of 20th century
o still understanding
Upon discovery, vitamins proved to reverse diseases in people whose diets were deficient
o led people to believe they were “magical”
o even today supplement business (multi-billion $$)
“the only disease a vitamin can cure is the one caused by a deficiency of that vitamin”
Classifications of Vitamins
Fat & water soluble (p. 221)
o how absorbed, transported, stored, how easily lost
Fat soluble (A, D, E, K)
o absorbed with fat (require bile), carried by proteins, stored in fat, not easily lost
 stored in liver & fatty tissue until needed; allows us to NOT need them daily
o can become toxic
o generally occur in fats & oils of foods
Water soluble (B complex & C)
o absorbed with water, transported in blood, no sig. storage, easily excreted in urine
o < risk of toxicity**, need more regular basis
Vitamin A
o vision
o immune defenses (role in regulation of genes that produce immune system proteins)
o normal cell development (promotes cell differentiation)
 skin, bone & body growth (children)
Preformed Vitamin A only in animal products
o liver & fish oil best
Fruits & Vegetables contain precursor - beta carotine
o beta carotine acts as an anti-oxidant
o low beta-carotine; may have higher risk of certain cancers, macular degeneration (life long poor
diets)
o research does NOT show supplementation has same effect as beta-carotene in food
Fast foods low levels
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Avoid supplements exceeding recommendations
o Excess vitamins A and D from supplements can easily reach toxic levels (excess beta-carotene
will not cause vitamin A toxicity)
RDA - 800-1000 RE or 900 micrcrograms
1/2 cup of carrots = 670 micrograms
o 1 IU = 0.3 micrograms retinol
Vitamin D
Body can synthesize from sun
o therefore, NOT essential
Function:
Helps to maintain blood Ca++ levels (bone)
o promotes Ca++ absorption from intestines
o prevents Ca++ excretion at kidneys
*Roles not fully understood (brain, pancreas, skin, reproductive organs)
Deficiencies
Rickets – weak bones
 rare in U.S.
Osteomalacia – (adult rickets)
 softening of bones
 elderly
o May also be associated with:
 High blood pressure, some cancers, type 1 diabetes, heart disease, rheumatoid arthritis,
multiple sclerosis
Toxicities
o most potentially toxic vitamin
o Excess vitamins A and D from supplements can easily reach toxic levels (calcification of soft
tissue)
Vitamin E (“alpha tocopherol”)
Functions
o anti-oxidant” – serves to defend against “oxidation”
o may help to prevent against heart disease
Deficiencies - seen with mal-absorption of fat
o extremely low fat diets
o heavy fat substitutes or “fat blocking agents” use
o high heating to oils (fast food)
o exercisers may have > need
Vitamin K
Needed for synthesis of proteins required for blood clotting & bone formation
o interferes with function of blood thinners
Produced by bacteria in colon (1/2 of what is needed)
Deficiencies are rare: infants & those taking long term antibiotics
o problems with blood clotting
Toxicity – seen with supplementation (infants & pregnancy)
o so by prescription only
Water Soluble Vitamins
B vitamins & Vitamin C
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Cooking & washing can reduce them in foods b/c water soluble
In healthy diet, may be wasting your money to supplement (expensive urine)
Physically active have higher needs however, should be made up for by increased energy consumption
B Vitamins
As a group, involved in breaking down fats, carbohydrates, & proteins to use as fuel
o Thiamin (B1), riboflavin (B2), niacin (B3), B6, B12, folic acid, pantothenic acid, & biotin
They do NOT contain energy, but are involved in production of energy
Deficiencies - exhaustion, depression, impairment of immune system, skin conditions
Niacin
Functions
o energy metabolism
Supplements are common b/c it is believed to reduce development of “atherosclerosis” & help with
diabetes (termed a “drug”)
o lower cholesterol levels
Can cause “niacin flush” (dilated capillaries)
o improper doses can damage liver & vision
Folate (folic acid)
Function
o required to make new cells
Blood cells & digestive cells reproduce most rapidly, anemia & digestive problems are common with
deficiency
Deficiency seen in this country
o associated with birth defects (neural tube - spine problems & mental retardation) 1 in 1000 births
o defects occur in 1st few weeks of pregnancy (before most women know)
Childbearing age consume 400 ug in addition to normal diet
Vitamin B12
Function
o helps folate make red blood cells
o develop sheath around nerve cells (protect nerves)
Deficiency
o “pernicious anemia”
o nerve damage
**only found in animal products
o vegetarians & those pregnant are of concern
How Are B Vitamins Related to Heart Disease?
Homocysteine
o amino acid in blood for purpose of building protein
o high levels correlate with a severe early form of cardiovascular disease (CVD)
 May damage blood vessel lining
 May make blood clot
 May oxidize LDL’s
 may be an indicator of CVD risk
Deficiencies of folic acid, vitamin B12 or vitamin B6 cause excess homocysteine to build up in the
blood
Future???
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Vitamin C
Functions
production of collagen (connective tissues)
enhances immune response
anti-oxidant (high doses however, act as “pro-oxidant”)
promotes absorption of iron
RDA – 60-100mg (10mg prevents scurvy)
o smokers may require closer to 100mg
Deficiencies
o collagen breakdown, loss of appetite, growth cessation, bleeding gums (scurvy)
Vitamin C & Common Cold
No study has conclusively proved vitamin can prevent or reduce colds; however, they are some studies
suggest this (1000mg/day); be careful of placebo effect
Need for Supplementation p. 261
Malnurished - we see clinical signs
Subclinical or marginal deficiencies
o subtle signs, no outward signs, or masked as non-nutritionally related
Always make sure nutrition is proper
Supplementation is appropriate in certain situations
Women childbearing yrs/Pregnant or Lactating
o Folic acid (neural tube defects)
Newborns
o Vitamin K; formula
Lactose intolerant
o Calcium
Females
o Calcium??
Strict vegetarians
o B12
Heavy Exercisers
o Vitamin E?
Smokers
o Vitamin E & C
Habitual dieters, Elderly, Specific diseases or medications
**watch high doses over long term
Anti-Oxidants Continued
Oxidants are constantly attacking us, so…
Defense against free radical damage
o anti-oxidant vitamins (vitamin E & C, beta-carotene, & phytochemicals)
o scavenge free radicals
Vitamin E & beta-carotene defend lipids & LDL’s
Vitamin C protects watery components