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Vitamins: An Overview. Vitamins. Essential organic substances (contain carbon) Not synthesized Inadequate synthesis Yield no energy, but facilitate energy-yielding chemical reactions If absent from a diet, it will produce deficiency signs and symptoms. Body Needs Vitamins for Normal.

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vitamins
Vitamins
  • Essential organic substances (contain carbon)
    • Not synthesized
    • Inadequate synthesis
  • Yield no energy, but facilitate energy-yielding chemical reactions
  • If absent from a diet, it will produce deficiency signs and symptoms
body needs vitamins for normal
Body Needs Vitamins for Normal
  • Function
  • Growth
  • Maintenance
  • Reproduction
two forms of vitamins
Two Forms of Vitamins
  • Precursor/Provitamin
    • Dietary form inactive
    • Activated in body
  • Active form
    • Dietary form active
    • Not changed in body
vitamin classification
Vitamin Classification
  • Fat-soluble vitamins
    • Dissolve in substances such as ether and benzene but not readily in water
    • Include vitamins A, D, E, and K
  • Water-soluble vitamins
    • Vitamins that dissolve in water
    • Include B vitamins and vitamin C
vitamin classification1
Vitamin Classification

Category determines

  • Food sources
  • How handled in body
  • Best preservation methods
vitamin history
Vitamin History
  • First discovered: fat soluble substance essential for health in 1912-1914 (vitamin A)
  • B complex: 1915-1916 (water soluble nutrient)
  • Vitamin C: isolated 1912
  • Vitamin D, Vitamin E: 1922
  • Last vitamin (B12) discovered in 1948
  • Likely all vitamins have been discovered, since people can be maintained on IV solutions fortified with known vitamins
vitamin facts
Vitamin Facts
  • Megadose (>10x needs) proved useful in treating certain conditions
  • Plant and animal foods provide vitamins
  • Synthesized vitamins work equally well in the body
fat soluble vitamins
Fat-Soluble Vitamins
  • Dissolve in organic solvents
  • Not readily excreted; can cause toxicity
  • Absorbed along with fat
    • Deficiency with fat malabsorption
    • Fat blockers (Orlistat/Xenical)
    • Mineral oil
fat soluble vitamins1
Fat Soluble Vitamins
  • Requires protein carrier
    • Transported like fat in chylomicrons, VLDL, LDL
  • Stored in body (except Vitamin K)
    • Fat tissue/liver
    • Can cause toxicity
    • Vitamin D and A most likely to be toxic
fat soluble vitamin preservation
Fat Soluble Vitamin Preservation
  • Not easily destroyed
  • Fat addition in cooking vegetables
    • Fat soluble vitamins leach out
    • Lost if liquid discarded
    • Add fat after vegetables drained, just before serving
  • Baking soda
    • Used to preserve color of green vegetables
    • Destroys Vitamin D
water soluble vitamins
Water Soluble Vitamins
  • Found in grains, fruits, vegetables, meat
  • Low risk of toxicity
    • Not stored in large amounts
    • Excess excreted inurine
    • Need daily intakes
  • Easily destroyed
    • Heat – increases enzyme activity
    • Light – destroys riboflavin
    • Oxygen: breaks down
water soluble vitamins preservation
Water Soluble Vitamins - Preservation
  • Cooking
    • Heat – destroys vitamins
    • Water – leaches out vitamins
    • Baking soda – destroys thiamin
  • Conserve vitamins
    • Store foods covered in refrigerator
    • Consume soon after purchase (freshest possible)
    • Minimal cooking/minimal liquid
    • Freezing preserves vitamin content
vitamin a
Vitamin A
  • Deficiency is most common cause of non-accidental blindness worldwide
  • Up to 500,000 children in developing nations especially Asia, become blind each year because of Vitamin A deficiency
functions of vitamin a
Functions of Vitamin A
  • Prevents night blindness
  • Prevents xerophthalmia (dry eye)
  • Maintains cell health (epithelial cells)
  • Growth, development, reproduction
  • Cardiovascular disease prevention
  • Cancer prevention
night blindness
Night Blindness
  • Vitamin A is needed for dark vision
  • Rhodopsin in retina
    • Light destroys
    • Constantly reformed
  • Allows for a chemical process to signal the brain that light is striking the eye
  • Allows eyes to adjust to dark vision
xeropthalmia
Xeropthalmia
  • In Vitamin A deficiency, the cells that line the cornea lose their ability to produce mucus
  • When dirt particles scratch the dry surface of the eye, becomes infected
  • Leads to blindness
  • Worldwide public health efforts are fortifying sugar, margarine, MSG, giving large doses of Vitamin A 2x year
macular degeneration
Macular Degeneration
  • Leading cause of legal blindness among North American adults over 65
  • Changes in the macular area of the eye
  • Age, smoking, and genetics are risk factors
  • Macula contains carotenoids lutein and zeaxanthin
  • High intakes of carotenoids associated with lower risk (but may be fruit and vegetable intake)
  • Also may reduce risk of cataracts
  • Multivitamins are adding lutein
cell health
Cell Health
  • Vitamin A maintains health of cells that line internal and external surfaces (epithelial cells)
  • Barriers to bacterial infections
  • Epithelial cells produce mucus
  • Without vitamin A, these cells do not produce mucus
  • Increases infections and decreases immune system
growth
Growth
  • Vitamin A binds to DNA
  • Assists in protein synthesis
  • Affects growth, reproductive system, and bone growth
cancer and cardiovascular disease
Cancer and Cardiovascular Disease
  • Role in cell development and immune-system
  • Role as an antioxidant
  • Lower risk of breast cancer with vitamin A supplements
  • Megadoses are not recommended
  • Mixed results in cancer/vitamin A studies
  • Foods rich in vitamin A and other phytochemicals are advised
prostate cancer and carotenoids
Prostate Cancer and Carotenoids
  • One of the most common cancers among North American men
  • Lycopene (tomatoes, watermelon, other fruits) seems to protect against it, possibly due to antioxidant activity
vitamin a and your skin
Vitamin A and Your Skin
  • Topical treatment and oral drug
  • Accutane (oral) and Retin-A (topical)
  • Can induce toxicity symptoms
  • Contraindicated in pregnant women
  • Use only under supervision of a physician
sources of vitamin a
Sources of Vitamin A
  • Preformed
    • Liver, fish oils, fortified milk, eggs
    • Contributes to half of vitamin A intake in North America
  • Provitamin
    • Dark leafy green, yellow-orange vegetables/fruits; carrots, spinach and other greens, winter squash, sweet potatoes, broccoli, mangoes, cantaloupe, peaches and apricots
    • Contributes to half of all the vitamin A intake
deficiency of vitamin a
Deficiency of Vitamin A
  • Night blindness
  • Decrease mucus production leading to bacterial invasion in the eye
  • Irreversible blindness
deficiency of vitamin a1
Deficiency of Vitamin A
  • Follicular hyperkeratosis
  • Keratin protects the inner layers of skin and maintains moisture
  • Kertinized cells replaces the normal epithelial cells in the underlying skin layers
  • Hair follicles become plugged
  • Bumpy, rough, and dry skin
measuring vitamin a
Measuring Vitamin A
  • International unit (IU)-crude method of measurement
  • Retinol activity equivalent (RAE) -current, more precise method of measurement

1 ug of retinol = 1 RAE = 3.3 IU =12 ug beta-carotene = 24 ug of other provitamin A

rda for vitamin a for adults
RDA for Vitamin A for Adults
  • 900 mcg REA for men
  • 700 mcg REA for women
  • Average intake meets RDA
  • Daily value used on food and supplement labels is 1000 mcg
  • Much stored in the liver
  • Vitamin A supplements are unnecessary
  • No separate RDA for carotenoids
who is at risk for deficiency
Who is at Risk For Deficiency
  • Breast fed infants
  • Preschooler with poor vegetable intake
  • Urban poor
  • Elderly
  • Alcoholics and people with liver disease
  • Individual with fat malabsorption
  • HIV, AIDS
toxicity of vitamin a
Toxicity of Vitamin A
  • Large intake of vitamin A over a long period: supplements, liver, fish oil
  • Bone/muscle pain, loss of appetite, skin disorders, headache, dry skin, hair loss, increased liver size, vomiting
  • Possible permanent damage
  • Discontinue supplement
toxicity of vitamin a1
Toxicity of Vitamin A
  • May produce fetal malformations and spontaneous abortions in pregnant women
  • May occur with as little as 3 x RDA of preformed vitamin A
  • Pregnant women and women who may become pregnant should limit to 100% DV
  • Upper Level for Vitamin A
    • 3000 ug for adults
  • Fatal dose -12 g of vitamin A can be fatal
toxicity of carotenoids
Toxicity of Carotenoids
  • Don’t produce toxic effects because
    • Rate of conversion to Vitamin A is slow and regulated
    • Efficiency of absorption decreases as oral intake increases
carotenoids
Carotenoids

High amounts of carotenoids in the bloodstream

  • Excessive consumption of carrots/squash/beta-carotene supplements
  • Skin turns a yellow-orange color
vitamin d
Vitamin D
  • Prohormone
  • Derived from cholesterol
  • 90% of needs is synthesized from sun exposure
  • Insufficient sun exposure makes this a vitamin
sun exposure to prevent vitamin d deficiency
Sun Exposure to Prevent Vitamin D Deficiency
  • ~15 minutes 2-3 times a week
  • Between 8 a.m. and 4 p.m.
  • Hands, face, arms
  • Light skin
  • No sunscreen greater than SPF8
activation of vitamin d
Activation of Vitamin D

To become the active hormone, Vitamin D must be

  • Acted on by the liver to produce 25-hydroxyvitamin D
  • Acted on by the kidney to produce 1,25 dihydroxyvitamin D (active hormone form)
functions of vitamin d
Functions of Vitamin D
  • Regulates blood calcium
    • Regulates calcium and phosphorus absorption from the intestine
    • Reduces kidney excretion of calcium
    • Regulates calcium deposition in bones
    • Serum calcium involved in nerve transmission and muscle contraction
functions of vitamin d1
Functions of Vitamin D
  • Influences cell differentiation
    • Linked to reduction of breast, colon, and prostate cancer
    • Controls the growth of the parathyroid gland, aids in immune function, contributes to skin cell development
food sources of vitamin d
Food Sources of Vitamin D
  • Fatty fish (salmon, herring)
  • Fortified milk and yogurt
    • 10 mcg per quart in US and Canada
  • Some fortified cereal
the adequate intake ai for vitamin d
5 ug/d (200 IU/day) for adults under age 51

10-15 ug/day (400 - 600 IU/day) for older Americans

Light skinned individuals can produce enough vitamin D to meet the AI from casual sun exposure

Infants are born with enough vitamin D to last ~9 months of age.

The Adequate Intake (AI) for Vitamin D
vitamin d toxicity
Vitamin D Toxicity
  • Upper level is 50 mcg/day
  • Vitamin D can be very toxic especially in children
  • Regular intake of 5-10x the AI can be toxic
  • Results from excess supplementation (not from sun exposure or milk consumption)
vitamin d toxicity1
Vitamin D Toxicity
  • Signs/symptoms: overabsorption of calcium (hypercalcemia)
  • Signs of high blood calcium: weakness, loss of appetite, diarrhea, vomiting, mental confusion, increased urine output
  • Calcium deposits in kidneys, heart, and blood vessels
  • Mental retardation in infants
vitamin d deficiency
Vitamin D Deficiency

At risk

  • Dark skinned
  • Lack of sun exposure
  • Northern climates in wintertime
  • Breastfed babies
vitamin d deficiency rickets
Vitamin D Deficiency: Rickets
  • Is the result of vitamin D deficiency in children
  • Poor mineralization of bones because of low calcium content
  • Fortification of milk has greatly reduced rickets in children
  • Most rickets is associated with fat malabsorption, as in cystic fibrosis
vitamin d deficiency osteomalacia soft bone
Vitamin D Deficiency: Osteomalacia (soft bone)
  • Is rickets in the adult
  • Low calcium content in bones due to lack of vitamin D
vitamin e
Vitamin E
  • Group of fat-soluble compounds, tocopherols and tocotrienols
  • Alpha-tocopherol is the most potent
  • Fat-soluble antioxidant
  • Resides mostly in cell membranes
redox agent
Redox Agent
  • Vitamin E is able to donate electron to oxidizing agent
  • Protects the cell from attack by free radicals
  • Protects PUFAs within the cell membrane and plasma lipoproteins
  • Prevents cell death
  • Prevents the alteration of cell’s DNA and risk for cancer development
the more the better
The More The Better?
  • Vitamin E is only one of many antioxidants
  • It is likely that the combination of antioxidants is more effective
  • Best to diversify antioxidant intake with a balanced and varied diet
  • Megadose of one antioxidant may interfere with the action of another
vitamin e and cardiovascular disease
Vitamin E and Cardiovascular Disease
  • Epidemiological studies suggest higher intakes of Vitamin E are associated with lower risk of CHD
  • Clinical trial results have been mixed
  • American Heart Association states it is premature to recommend vitamin E supplements to the general population
  • FDA has denied permission for supplement mfr’s to claim that Vitamin E prevents heart disease and cancer
other functions of vitamin e
Other Functions of Vitamin E
  • Protects the double bonds in saturated fat
  • Helps vitamin A absorption
  • Role in iron metabolism
  • Inhibits LDL oxidation
  • Maintenance of nervous tissue and immune function
food sources of vitamin e
Food Sources of Vitamin E
  • Plant oils: salad dressings, mayonnaise
  • Fortified cereals, oatmeal
  • Wheat germ
  • Asparagus, tomatoes, green leafy vegetables
food sources of vitamin e1
Food Sources of Vitamin E
  • Peanuts
  • Margarine
  • Nuts and seeds (sunflower seeds)
  • Actual amount is dependent on harvesting, processing, storage and cooking
vitamin e easily damaged
Vitamin E: Easily Damaged
  • Oxygen
  • Metals
  • Light
  • High heat
    • Deep fat frying
rda for vitamin e
RDA for Vitamin E
  • 15 mg/day alpha-tocopherol for women and men
  • (=22 IU of natural source or 33 IU of synthetic form)
  • Average intake meets RDA

1 mg d--tocopherol = 0.45 IU (synthetic source)

1 mg d--tocopherol = 0.67 IU (natural sources)

deficiency of vitamin e
Deficiency of Vitamin E
  • Hemolytic anemia
  • Hemolysis occurs in preterm infants because they did not receive enough vitamin E from their mothers
  • Preemie formulas and supplements compensate for increased needs
deficiency of vitamin e who s at risk
Deficiency of Vitamin E: Who’s At Risk?
  • Smokers are especially at risk (smoking destroys vitamin E in the lungs)
    • However even megadoses may not prevent damage
  • Adults on very low fat diets
  • Fat malabsorption
toxicity of vitamin e
Toxicity of Vitamin E
  • Supplements up to 800 IU probably harmless
  • Upper Level is 1,000 mg/day of any form of supplementary alpha-tocopherol
  • Upper Level is 1500 IU (natural sources) or 1100 IU (synthetic forms)
  • Inhibits vitamin K metabolism especially in conjunction with anticoagulants
  • Possible hemorrhage
vitamin k koagulation
Vitamin K (“Koagulation”)
  • Family of compounds found in plants, plant oils, fish oils, and meats
  • Synthesized by the bacteria in the colon and are absorbed (10% of needs)
role of vitamin k
Role of Vitamin K
  • Role in the coagulation process
    • Contributes to the synthesis of several blood-clotting factors
  • Helps form proteins present in bone, muscle, and kidneys
    • Imparts calcium-binding potential
    • Poor intake linked to increase in hip fractures
vitamin k in newborns
Vitamin K in Newborns
  • Newborn’s intestinal tract lacks bacteria to allow blood to clot effectively
  • Vitamin K is routinely given by injection shortly after birth to bridge the gap
  • May also occur in adults with chronic malabsorption
drugs and vitamin k
Drugs and Vitamin K
  • Anticoagulant
    • Lessens vitamin K reactivation
    • Lessens blood clotting process
    • Monitor vitamin K intake
  • Antibiotics
    • Destroy intestinal bacteria
    • Inhibit vitamin K synthesis and absorption
    • Potential for excessive bleeding
food sources of vitamin k
Food Sources of Vitamin K
  • Liver
  • Green leafy vegetables
  • Broccoli
  • Peas
  • Green beans
  • Soybeans/canola oil
  • Resistant to cooking losses
  • Limited vitamin K stored in the body
adequate intake for vitamin k
Adequate Intake for Vitamin K
  • 90 ug/day for women
  • 120 ug/day for men
  • Amount met by most
  • Excess vitamins A and E interferes with vitamin K
  • Newborns are injected with vitamin K (breast milk is a poor source)
  • Toxicity unlikely; readily excreted
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