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Supplements for athletes Vitamins – introduction Food safety - PowerPoint PPT Presentation

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Recap of last lecture Supplements for athletes Vitamins – introduction Food safety #16 Outline for today Fat-soluble vitamins overview Next time: Water-soluble vitamins Answers to some of your questions Cooking with a microwave Antibiotics (effects, in foods) Irradiation of foods

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Recap of last lecture

  • Supplements for athletes
  • Vitamins – introduction
  • Food safety

#16 Outline for today

  • Fat-soluble vitamins
    • overview
  • Next time: Water-soluble vitamins
answers to some of your questions
Answers to some of your questions
  • Cooking with a microwave
  • Antibiotics (effects, in foods)
  • Irradiation of foods
food preservation
Food preservation
  • Classical - Salt, sugar, smoke, drying, fermentation
    • Decrease water content except fermentation
  • Modern - Pasteurization, freezing, refrigeration, canning, preservatives, “sterilization”
  • Irradiation
    • Food is not radioactive
    • Kills bacteria
    • Approved – raw red meat, eggs, seeds (hot dogs?)
    • Effective on many others including fruits and vegies
  • There are 4 fat soluble vitamins
  • 9 water soluble vitamins for a total of 13.
  • Your text also lists choline with the water soluble vitamins although it is not considered a vitamin since there is no known deficiency disease
fat soluble vitamins overview
Fat-Soluble Vitamins Overview
  • Not readily excreted; can cause toxicity
  • Absorbed along with fat
  • Concern for people with fat malabsorption or use of certain medication (e.g. orlistat or Xenical)
  • Transported like fat in chylomicrons, VLDL, LDL
  • Mostly metabolized in liver


pro vitamins
  • Precursors of vitamins
  • Are converted into the active vitamin form
  • E. g. beta-carotene converted into vitamin A
vitamin a
Vitamin A
  • Chemical names: 3 forms: retinol, retinal, retinoic acid
  • Most common cause of non-accidental blindness, worldwide
  • Active forms
    • Retinoids (retinal, retinol, retinoic acid)
    • Found in animal products
  • Pro-forms
    • Carotenoids (beta-carotene, alpha carotene,lutien, lycopene, zeaxanthin)
    • Must be converted to retinoid form
    • Found in plant products
terminal ends of retinoids
Terminal Ends of Retinoids

Retinyl esters beta-carotene




Retinol Retinal Retinoic Acid

Retinyl esters beta-carotene




Retinol Retinal Retinoic Acid

functions of vitamin a
Functions of Vitamin A
  • Retinol is needed for reproduction
  • Retinoic acid supports growth and cell maturation (also anti-acne medication)
  • Retinal is needed for night and color vision
  • Major use is in cell differentiation
  • Also act as antioxidants
the visual cycle
The Visual Cycle
  • Cones in the retina
    • Responsible for vision under bright lights
    • Translate objects to color
  • Rods in the retina
    • Responsible for vision in dim light
    • Translate objects to black and white
absorption of vitamin a
Absorption of Vitamin A
  • Requires bile, digestive enzymes
  • Dependent on the fat in the diet
  • 90% of retinoids can be absorbed
  • Only ~30% of carotenoids are absorbed
  • Intestinal cells convert carotenoids to retinoids
transport and storage of vitamin a
Transport and Storage of Vitamin A
  • Liver stores 90% of vitamin A in the body
  • Reserve is adequate for several months
  • Transported via chylomicrons to the liver
  • Transported from the liver as retinol via retinol-binding protein to target tissue
  • Carotenoids can be transported via VLDLs
vitamin a and resistance to disease
Vitamin A and resistance to disease
  • Deficiency leads to epithelial (skin) cell problems – allowing cracks and bacterial invasion
  • Deficiency leads to poor mucus formation
  • Deficiency reduces activity of some immune-system cells
  • High-dose therapy of vitamin A increases immune response
cancer and carotenoids
Cancer and Carotenoids
  • Role in cell development and immune-system
  • Role as an antioxidant
  • Lower risk of breast cancer with vitamin A supplements
  • Megadoses not advised
  • Mixed results in cancer/vitamin A studies
  • Foods rich in vitamin A and other phytochemicals are advised
sources of vitamin a
Sources of Vitamin A
  • Preformed
    • Liver, fish oils, fortified milk, eggs
    • Typically contributes half of vitamin A intake
  • Pro-forms
    • Dark leafy green , yellow-orange vegetables/fruits
    • Typically contributes half of vitamin A intake
deficiency of vitamin a
Deficiency of Vitamin A
  • Night blindness
  • Decreased mucus production
  • Leading to bacterial invasion in the eye
    • Conjunctival xerosis
    • Bitot’s spots
    • xerophthalmia
  • Irreversible blindness
toxicity of vitamin a
Toxicity of Vitamin A

Hypervitaminosis A

  • Result of long-term supplement use (3-10x >RDA)


  • Ingestion of LARGE dose(s) of vitamin A (within a short period)
  • Result in intestinal upset, headache, blurred vision, muscular incoordination
  • Symptoms disappear when supplements are stopped
  • Can be lethal
toxicity of vitamin a19
Toxicity of Vitamin A


Large intake of vitamin A over a long period

Bone/muscle pain, loss of appetite, skin disorders, headache, dry skin, hair loss, increased liver size, vomiting

Discontinue supplement is recommended

Possible permanent damage

toxicity of vitamin a20
Toxicity of Vitamin A


  • Tends to produce physical defect on developing fetus as a result of excess vitamin A intake
  • Spontaneous abortion, birth defects
  • May occur with as little as 3 x RDA of preformed vitamin A

Upper Level for Vitamin A

  • 3000ug for adults

Fatal dose -12 g of vitamin A can be fatal

vitamin d
Vitamin D
  • Prohormone (conversion of vitamin D-3 into the hormone 1,25-dihydroxy-calciferol = calcitriol)
  • Derived from cholesterol
  • Synthesis from sun exposure
  • Insufficient sun exposure makes this a vitamin
  • Activated by enzymes in liver and kidneys
  • Deficiency can cause diseases
absorption of vitamin d
Absorption of Vitamin D
  • ~80% of vitamin D consumed is incorporated into micelles
  • Absorbed in the small intestine and transported via chylomicrons
  • Transported through the lymphatic system
metabolism and storage of vitamin d
Metabolism and Storage of Vitamin D
  • Activation by the liver and the kidneys
  • Stored in fat tissue
  • Activate vitamin D when calcium is inadequate
  • Excretion of vitamin D mainly via bile
vitamin d and cell differentiation
Calcitriol is able to influence differentiation and function of some cells

Linked to reduction of breast, colon, and prostate cancer development

Vitamin D and Cell Differentiation
role in bone formation
Calcitriol creates a supersaturated Ca + Phos solution

Causes Ca + Phos to deposit in the bones

Strengthen bones

Rickets is the result of low vitamin D

Osteomalacia (soft bone) is rickets in the adult

Role in Bone Formation
food sources of vitamin d
Food Sources of Vitamin D
  • Fatty fish (salmon, herring)
  • Fortified milk
  • Some fortified cereal
toxicity warning
Toxicity Warning
  • Vitamin D can be very toxic
  • Regular intake of 5-10x the AI can be toxic
  • Results from excess supplementation (not from sun exposure or milk consumption)
  • Sign and symptoms: over absorption of calcium (hypercalcemia), increase calcium excretion
  • Calcium deposits in kidneys, heart, and blood vessels, narrowing of pulmonary arteries and aorta, facial changes, mental retardation
vitamin e
Vitamin E
  • Tocopherols and tocotrienols
  • Amount absorbed is dependent on fat intake
  • Dependent on bile and pancreatic enzyme for absorption
  • Incorporated into chylomicrons to the liver then incorporated into lipoproteins
  • Stored in adipose tissue, liver, and muscle
  • Found in cell membranes
  • Protects the cell from attack by free radicals and ROS = reactive oxygen species
  • Peroxyl-radical from fat breakdown
  • Protects PUFAs within the cell membrane and plasma lipoproteins
  • Prevents the alteration of cell’s DNA and risk for cancer development
free radicals
Free Radicals
  • Production is normal result of cell metabolism
  • Destructive to cells; sets off a chain reaction
  • Lipid peroxidation
  • More vitamin E is found in the lungs
  • Smoking causes significant oxidative damage
protection from oxidative damage
Protection From Oxidative Damage
  • Glutathione peroxidase
    • A selenium containing enzyme
    • Helps breakdown peroxidized fatty acids (that tends to form free radical)
    • Lessens the burden of vitamin E
  • Superoxide dismutase and catalase
    • React with peroxide and superoxide (free radicals)
    • Reduce free radical activity
the more the better
The More The Better?
  • Vitamin E is only one of many antioxidant
  • It is likely that the combination of antioxidant is more effective
  • Diversify your antioxidant intake with a balanced and varied diet
  • Megadose of one antioxidant may interfere with the action of another
  • Supplement of vitamin E for CVD is questionable