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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


Role in bone formation

Vitamin D causes Ca + Phos to deposit in the bones

Strengthen bones

Role in Bone Formation


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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