Lecture 21 Vitamins

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Lecture 21 Vitamins
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1. What are vitamins?

• 13 different compounds Vitamins
• no legal/official definition
• accepted description
• organic nutritional substances

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Original description

• accessory food factors
• prevented deficiency diseases such as
• Pellagra (Vitamin B3 - Niacin)
• Scurvy (Vitamin C)
• Rickets (Vitamin D)
• Night Blindness (Vitamin A)
• Haemorrhagic Diseases (Vitamin K)

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Vitamins cont..

• Deficiency diseases in developing countries due
  to
• scarcity of food
• ignorance of well balanced diet
• cultural food practices
• originally TERMED
• Vitamine Vital Amine

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Vitamins cont..

• originally named by LETTER or FUNCTION
• Vitamin B1 anti Beriberi Vitamin
• B for beriberi
• names now related to CHEMICAL STRUCTURE
• Vitamin B1
• Thiamin
• Sulphur (Greek Thia) Amino group

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Synthesis

• We cannot synthesise vitamins
• except Vitamin K
• Vitamin B1
• Vitamin B12
• Folate
• these vitamins synthesised by gut bacteria
• NOT made in quantities that meet RDI
• MUST be obtained from FOOD

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Classification

• Vitamins classified into 2 groups
• WATER SOLUBLE
• not stored in body
• FAT SOLUBLE
• stored in adipose tissue liver

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• WATER SOLUBLE
• Thiamin (B1)
• Riboflavin (B2)
• Niacin (B3)
• Pyridoxine group (Vitamin B6)
• Pantothenic Acid (B5)
• Biotin
• Vitamin C
• ALL involved in mitochondrial Energy metabolism
• ?-Carotene

• FAT SOLUBLE
• Vitamin A
• Vitamin D
• Vitamin E
• Vitamin K
• Vitamin E only fat soluble vitamin involved in
  Energy metabolism

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Pantothenic acid

• classified with B-group vitamins
• not strictly a vitamin
• actually a part of Co-enzyme A
• involved with other B-group vitamins
• conversion of CHO ? energy
• no RDI in Australia
• food sources liver, eggs, fava beans (broad
  beans)

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2. What do vitamins do?

• NOT an energy source
• assist enzymes in various biochemical functions
• eg. conversion of CHO to energy
• co-enzymes Vitamins B2 (Riboflavin) B3
  (Niacin)

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Effects of cooking storage

• UNSTABLE OXIDISED during cooking storage
• water-soluble vitamins particularly vulnerable
• prolonged heating can destroy up to 40 of
  available B-group vitamins

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3. Excess vitamin intake

• unused water-soluble vitamins EXCRETED in urine
• no toxicity risks
• except Vitamin C ?
• fat-soluble vitamins STORED in liver
• can reach toxic levels if over-consumption
  (mega-doses of supplements ONLY)

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4. Deficient vitamin intake

• water-soluble vitamins
• single days omission does NOT create deficiency
• but still need regular intake
• fat-soluble vitamins
• daily intake not necessary
• stored in liver

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Vitamin Imposters

• substances thought essential for human life
• only essential for bacteria and other
  micro-organisms
• translated by Pseudoscience into human needs
• Placebo effect
• examples.

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Vitamin Imposters

• Co-enzyme Q10 (Ubiquinone)
• involved in the electron transfer chain (Energy
  production)
• Supplementation ? ? energy production!!
• Carnitine
• involved in mitochondrial fat metabolism for
  Energy production
• we synthesise Carnitine according to fat load
• Supplements do NOT increase fat oxidation!!

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Vitamin Imposters

• Vitamin B-15 (Pangamic acid)
• No such vitamin compound exists!!

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Recommended Reading

• Whitney Rolfes (10th Ed.) 2005
• Understanding Nutrition
• Chapter 10. The Water Soluble Vitamins
• NB. Highlight 10Vitamin Mineral supplements
• Chapter 11. The Fat Soluble Vitamins
• exam questions will also come from the readings

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Vitamins Controversial issues

• Video
• ABC Catalyst programme
• Vitamin Supplementation