Kin 110 Lecture 6

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Kin 110 Lecture 6

• Vitamins Ch. 8

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Learning Objectives

• Define vitamin
• Classify vitamins as fat-soluble or water-soluble
• List the major functions and deficiency symptoms
  for each fat-soluble vitamin
• List three important food sources for each
  fat-soluble vitamin
• Describe toxicity symptoms for excess consumption
  of certain fat-soluble vitamins
• Evaluate the use of vitamin supplements - risk /
  benefit

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Vitamins

• Vitamin essential organic (contains carbon)
  substances needed in small amounts in diet
• Required for normal function, growth, maintenance
  of body structures
• Yield no energy, but participate in energy
  yielding reactions
• fat soluble vitamins - ADEK
• water soluble vitamins-B vitamins and C
• co-enzymes help enzymes function
• B vitamins and vitamin K
• Fig. 8-1

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Vitamins

• To be classified as vitamin
• Body unable to synthesize enough
• Absence for a defined period of time must produce
  deficiency (fig 8.2)
• symptoms, if caught in time, are cured when
  substance is reintroduced to diet
• Megadoses of Vitamins
• Requires Medical supervision
• Toxicity diseases are possible
• Many unproven claims continually being made
• Niacin - cholesterol lowering
• Vit D - treatment of psoriasis
• Have they all been found?
• People living on intravenous solutions of
  Protein, Carbohydrates, Fat and all known
  vitamins and minerals survive, grow, reproduce
  and fight disease

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Storage of Vitamins

• Fat soluble vitamins A, E and D not readily
  excreted
• Water soluble - lost from body quite rapidly (B6
  and B12 stored)
• In general, limited storage of vitamins
• should be consumed daily

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Vitamin Toxicity

• Toxicity theoretical for all vitamins
• Fat soluble more frequently observe toxicity (A
  and D)
• E, Niacin, B-6 and C very large amounts needed
  to result in toxicity
• Only possible from supplements
• A and D only 3-5 times RDA needed on a regular
  basis for toxicity
• Vit A important to minimize in early pregnancy
• Once a day vitamins, less than 2 times daily
  value not a risk
• Preserving vitamin content - Table 8.1

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Fat soluble Vitamins

• ADEK
• Table 8.2
• Absorbed along with dietary fat
• Travel in bloodstream along with fat to reach
  body cells
• Stored in liver and fatty tissue
• 40-90 of fat sol. vit. absorbed
• Can be reduced further interference in normal
  digestion and absorption of fats.
• Eg. Mineral oil laxatives

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Vitamin A

• Easy to over dose (toxic) and be deficient
• Both cause severe problems
• Variety of forms
• Retinoids
• Preformed vitamin A
• Only found in animal foods
• Carotenoids pro-vitamin A
• plants
• Yellow-orange pigment in carrots
• Turned into vitamin A as needed
• Most potent form is beta-carotene
• Both pre and pro referred to as Vitamin A

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Functions of Vitamin A

• Many roles not all well understood
• Role in vision best known and most clearly
  understood
• Performs important functions is both light (day)
  and dark (night) vision
• in dim light, one form of A is required to start
  the chemical process that signals the brain that
  light is striking the eye.
• Without vit A night blindness
• Prolonged deficiency cells unable to produce
  mucus for cornea
• Dry, dirty, scratched, infected
• Xeropthalmia - dry eye
• Less-developed nations children
• Blindness. Infection, death

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Health of Cells

• Vitamin A maintains health of all cells that
  line internal and external surfaces
• Lungs, intestines, stomach, eyes, skin
  (epithelial cells)
• Cells secrete mucus lubricant
• Without A decrease activity of immune cells,
  increased infection
• Carotenoids play a role in preventing
  cardiovascular disease
• Needed for growth, Development and Reproduction
• Synthesis of proteins that stimulate proper
  growth and development
• Resorbing and producing bone

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Cancer and Vitamin A

• Skin, lung, bladder and breast cancer
• Adequate intake of vitamin A can lower risk of
  breast cancer
• Megadoses NOT recommended to prevent cancer
• Carotenoids trap energy in free radicals
  oxidation can initiate cancer process
• Supplements of b-carotene not effective
• Variety of fresh fruits and vegetables
• Lycopene - tomatoes - may prevent prostate cancer
• Acne topical and internal derivatives
• May produce birth defects in pregnant women using
  treatments
• Eg retin-A and accutane

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Vitamin A in Food

• Preformed vitamin A
• liver, fish oils, fortified milk and cereal,
  butter, margarine, eggs
• Pro-vitamin dark green and orange vegetables
• Carrots, spinach, winter squash, papaya,
  apricots, sweet potatoes
• RDA RAE- retinol activity equivalent
• 900 mg RAE (males)
• 700 mg RAE (females)
• Due to difficulty in classifying contributions
  from preformed and pro-vitamin A sources the
  labeling has undergone changes recently
• Very old - IU, old RA, now RAE
• Risk of deficiency children, poor, alcoholics
• Dietary sources table fig 8.3

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Toxicity of Vitamin A

• 3 times the RDA can cause problems if continued
  for prolonged periods
• Early pregnancy (pre-formed)
• Fetal malformations, birth defects, spontaneous
  abortion
• Non-pregnant skin, hair, internal organs and
  CNS
• Permanent damage can occur
• Vit A is stored for months
• Women in childbearing years limit to 100
  intake -one ounce of liver - 300
• Carotenoids (pro form) not toxic
• Rate of conversion is slow
• Efficiency of absorption decreases as intake
  increases

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Vitamin D

• Also considered a hormone
• skin cells convert cholesterol like substance
  into vitamin D using sunlight
• effects kidney and bone
• 10-15 minutes of exposure of arms, face and
  hands 2-3 times per week
• not effective in winter
• must have vitamin intake

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Functions of Vitamin D

• To become active hormone, vitamin D must be
  activated in liver and kidneys
• calcitrol - active form
• regulates calcium and bone metabolism along with
  parathyroid hormone
• regulates absorption of calcium and phosphate
  from intestines
• reduces kidney excretion of calcium
• regulates deposition of calcium in bones
• Immune system and skin development influenced by
  vitamin D

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Vitamin D and Bone

• Calcium and phosphorus deposition
• without vit D bones weaken and bow under pressure
• Rickets (children)
• fortification of milk -
• malabsorption of fat (cystic fibrosis)
• osteomalacia - adults - soft bones
• calcium withdrawn from bones
• inefficient absorption or conservation
• vit D deficient
• bones porous and weak - break easily
• supplement vit D - reduces fractures
• problem with vitamin D activation or absorption

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Dietary Sources of D

• Fatty fish (sardines, salmon), fortified milk,
  yogurt and cereals
• under 51 years - 5 mg/day
• over 51 2-3 times - 10-15 mg/day
• max. 50 mg /day
• Young, fair skinned 10-15 min of sun on face and
  arms 2-3 times /week
• 5-10 times recommended on regular basis results
  in toxicity
• calcium over absorption - deposition in kidneys
  and other organs
• high blood calcium
• Weakness, loss of appetite, diarrhea, vomiting ,
  mental confusion,
• sun exposure does not result in toxicity

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Vitamin E

• Fat soluble antioxidant -
• resides in cell membranes
• donates electrons - protection from free radicals
• fig 8-4
• DNA oxidation - cancer, cell death
• repair mechanisms for damage
• impact on cancer, heart disease very minimal
  compared to proper diet and exercise
• not an alternative to making good overall health
  choices

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Deficiency of vitamin E

• Few women getting enough vitamin E from food
• Supplements not as potent
• Smoking destroys vitamin E
• Cell membranes break down
• red blood cell breakdown in infants
• unsaturated fatty acids susceptible to oxidation
• hemolysis- breaking of rbc in absence of vit. E
• vit E improves vit A absorption
• used to metabolize iron in cell, maintain nervous
  tissue, and insulin function

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Vitamin E in Foods

• plant oils, fortified cereals, fruits and
  vegetables, eggs, margarine
• Sunflower seeds and almonds are an excellent
  source of vitamin E
• vitamin E in plant oils - protects unsaturated
  fatty acids
• Animal foods almost no vitamin E
• content of vit E depends on harvesting ,
  processing storage and cooking
• easily destroyed by oxygen, metals , light ,
  repeated frying
• RNI - 15 mg /day
• alpha tocopherol - most active form
• megadose therapy - not proven
• Upper level is 1000mg of supplement
• toxicity not a problem, except for people on
  anticoagulants (CVD) or with a vitamin K
  deficiency - due to increasesd risk of hemorrhage

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Vitamin K

• Family of compounds known collectively as vitamin
  K
• Found in plant oils, fish oils, and meats
• One form is synthesized by bacteria in the
  intestine (10 of need)
• role - vital for blood clotting
• synthesis of blood clotting factors
• formation of proteins in bone, kidney and muscle
• impart calcium binding potential
• newborns lack bacteria to produce vitamin K
• routine injection at birth
• deficiency in adults on prolonged antibiotics or
  with poor fat absorption

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Vitamin K in Food

• Liver, green leafy vegetables, broccoli, peas and
  green beans
• Also soybean and canola oils
• vitamin K not stored well - one day
• abundant in diet, deficiency uncommon
• resistant to cooking
• RDA - 90-120 mg / day
• no risk of toxicity
• risk of reduced effectiveness of medications to
  reduce blood clotting (CVD)

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Vitamin Supplements

• Supplements may be beneficial, and improve health
  of population
• Most unwilling to increase intake of fruits and
  vegetables
• folate (B vitamin)
• birth defects
• homocystien - risk factor for heart disease
• alleviated by adequate folate (and reduction in
  red meat)
• vitamin B12 - risk over 50
• synthetic more easily absorbed
• Eat right and take a multivitamin
• Use supplements in consultation with physician
• Potential impacts of medications for CVD and
  cancer

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Vitamin Supplements

• Megadoses of E and B12
• trials ongoing, may be beneficial
• Vit E not very exciting results
• Supplements should be taken with or just after
  meal
• no more than 100 of daily values
• avoid excess selenium and C
• overabsorption of iron
• males avoid excess iron
• excess zinc - inhibits iron an copper absorption
• excess folate - masks B12 deficiency
• avoid other products - PABA, inositol, bee
  pollen, lecithin