The Vitamins (Slide)
•They are organic non-energy yielding, micronutrients.
•They are necessary for normal metabolism in animals.
•They either are not synthesized in the body or are synthesized in inadequate
quantities. Hence they are essential nutrients (Vitamin D is an exception).
•Most vitamins function as coenzymes or cofactors.
•Deficiency states are recognized for all vitamins, and in many cases, excessive
intake also leads to disease.
The Vitamins
•Vitamins vs carbohydrates, fats, and proteins
–Structure (organic)
•They are not macromolecules made by linking individual units
–Function (non-energy yielding)
•Do not provide usable energy
•They are required to help the various enzymes in the body some of which help to release
the energy from food
–Food contents (micronutrients)
•Amounts in food and amounts required are measured in micrograms (as opposed to
grams and milligrams for other nutrients)
The Vitamins
•Bioavailability
–Amount of vitamin available in foods:
•Amount in food
•Amount absorbed and used by the body
–Determined by
•Efficiency of digestion
•Time to go through GI tract
•Previous nutrient intake and nutrition status
•Other foods consumed at the same time
–E.g. alcohol inhibits thiamin absorption
•Method of food preparation (raw, cooked or processed)
–Some vitamins may get leached out if cooked into too much water
–Some vitamins are inactivated by high heat
•Source of nutrient
–Synthetic
–Fortified
–Naturally occurring
The Vitamins
•Precursors
–Some vitamins are available in foods as precursors
–Necessary to measure amount of active vitamin plus potential amount available from
precursors
•E.g. tryptophan is a precursor for Niacin
•1 mg of Niacin required 60mg of dietary tryptophan
•So recommended intakes are in Niacin equivalents (NE)
•Organic nature
–Can be destroyed by heating, UV rays (sun) or fluorescent light (Riboflavin)
–Can be destroyed by oxidation (Vitamin C) cut fruits, fruit juices
–Table 10-1 “ Minimizing nutrient losses”
•Refrigerate, wash before cutting, use microwave oven or steam in small amount of
water, cook for short time, low temperature
The Vitamins
•Solubility
–Hydrophilic (water soluble)
•B Vitamins and Vitamin C
–Hydrophobic (fat soluble)
•Vitamins A, D, E and K
•Toxicity
–More is not necessarily better
–
Coenzymes: Figure 10-1
Thiamin
• Chief functions in the body
– Part of coenzyme TPP (thiamin pyrophosphate) used in energy
metabolism
– Required for the breakdown of glucose to release energy
– Required for the functioning of the nervous system, especially the
peripheral nerves, like those found in your hands and feet
– Vital for adequate muscle coordination
• Significant sources ( from lecture slide)
– Excellent and unusual sources from Figure 10-3
• Easily destroyed by heat
• Deficiency disease
• Deficiency symptoms
Riboflavin
• Chief functions in the body
– Part of coenzymes FMN (flavin mononucleotide) and FAD (flavin adenine
dinucleotide)
– These coenzymes are used in energy-yielding metabolic pathways from
both glucose and fatty acids
– Metabolism of certain vitamins and minerals also requires Riboflavin
• Significant sources ( from lecture slide)
– Excellent and unusual sources from Figure 10-5
• Easily destroyed by ultraviolet light and irradiation
• Deficiency disease: ariboflavinosis
• Deficiency symptoms
Niacin
• Chief functions in the body
– Part of coenzymes NAD (nicotinamide adenine dinucleotide) and NADP
(its phosphate form) used in energy metabolism
• Significant sources ( from lecture slide)
– Excellent and unusual sources from Figure 10-7
• Deficiency disease: pellagra
• Deficiency symptoms
• Toxicity Symptoms
Biotin
• Chief functions in the body
– Part of a coenzyme used in energy metabolism, fat synthesis, amino acid
metabolism, and glycogen synthesis
• Significant sources ( from lecture slide)
– Note role of avidin in eggs
• Deficiency Causes
• Deficiency Symptoms
Pantothenic Acid
• Chief functions in the body
– Part of coenzyme A, used in energy metabolism
• Significant sources ( from lecture slide)
• Easily destroyed by food processing
• Deficiency symptoms
Vitamin B6
• Stored extensively in muscle tissue (unlike other water soluble vitamins)
• Chief functions in the body
• Part of coenzymes PLP (pyridoxal phosphate) and PMP (pyridoxamine
phosphate) used in amino acid and fatty acid metabolism
• Helps to convert tryptophan to niacin and to serotonin
• Helps to make red blood cells
• Influences cognitive performance, immune function and steroid hormone activity
• Significant sources ( from lecture slide)
– Excellent and unusual sources from Figure 10-8
• Deficiency symptoms
• Toxicity symptoms
Folate
• Absorption and Activation – Figure 10-9
– Folate and B12 connection
• Absorption – slide
• Folate – importance in pregnant women and to prevent heart disease and cancer
• Chief functions in the body
– Part of coenzymes THF (tetrahydrofolate) and DHF (dihydrofolate) used
in DNA synthesis and therefore important in new cell formation
• Significant sources ( from lecture slide)
– Excellent and unusual sources from Figure 10-11
• Deficiency symptoms
• Toxicity symptoms
Vitamin B12
• Activation
– Folate
• Absorption
– HCl
– Pepsin
– Both these separate B12 from the proteins in the food
– Intrinsic factor
• Binds B12 and transports it to the end of the intestine where
intrinsic factor is destroyed and B12 is absorbed into the blood
• Chief functions in the body
– Part of coenzymes methylcobalamin and deoxyadenosylcobalamin used in
new cell synthesis
– Helps to maintain nerve cells
– Reforms folate coenzyme
– Helps to break down some fatty acids and amino acids
• Significant sources ( from lecture slide)
• Easily destroyed by microwave cooking
• Deficiency causes (from lecture slide)
• Deficiency disease: pernicious anemia
• Deficiency symptoms
The non-B Vitamins
• Choline (in summary table pg. 344
• Inositol
• Carnitine
•
The B Vitamins - In concert
• B vitamin toxicities
What is a free radical (lecture slides)
What is a free radical Figure H11-1
Antioxidant Nutrients In Disease Prevention
• Figure 11-12
• Lecture slides
• Defending against cancer
• Defending against cardiovascular disease
Vitamin C
• Figure 10-15
• Chief functions in the body
– Collagen synthesis
– Strengthens blood vessel walls, forms scar tissue, provides matrix for bone
growth
– Antioxidant
– Thyroxin synthesis
– Amino acid metabolism
– Strengthens resistance to infection
– Helps in absorption of iron
• Significant sources ( from lecture slide)
– Excellent and unusual sources from Figure 10-8
• Easily destroyed by heat and oxygen
• Deficiency disease: scurvy
• Deficiency symptoms
• Toxicity symptoms
Vitamin And Mineral Supplements (all from lecture slides)
• Arguments for supplements
• Arguments against supplements
• Bioavailability
• Antagonistic actions
• Selection of supplements
• Regulation of supplements
•
Vitamin A And Beta-Carotene
• Figure 11-2
• Retinol binding protein ( lecture slide)
• Roles in the body
– Vitamin A in vision (Figure 11-3)
• Cornea
• Retina
• Roles in the body (lecture slide)
• Deficiency disease: hypovitaminosis A
• Deficiency symptoms (lecture slide)
• Excess betacarotene from natural sources turns skin yellow but ok
• But supplements can be dangerous
• Toxicity disease: hypervitaminosis A
– Chronic toxicity symptoms
– Acute toxicity symptoms
• Sources (lecture slide)
•
– Retinol
– Beta-carotene
– Liver
– Excellent and unusual sources from Figure 11-8
Vitamin D
• Is actually a hormone
• Chief functions in the body
– Mineralization of bones (raises blood calcium and phosphorus by
increasing absorption from digestive tract, withdrawing calcium from
bones, stimulating retention by kidneys)
– May also be important for immune system, nervous system, skin and
reproductive organs
– May protect against multiple sclerosis
• Significant sources (lecture slide)
• Deficiency diseases
– Rickets (fontanel) Children
– Osteomalacia Adults
• Toxicity disease: hypervitaminosis D
• Toxicity symptoms
Vitamin E
• Chief function in the body
• Antioxidant (stabilization of cell membranes, regulation of oxidation reactions,
protection of polyunsaturated fatty acids and vitamin A)
– Figure 11-12
• Significant sources (lecture slide)
• Easily destroyed by heat and oxygen
• Deficiency symptoms
• Toxicity symptoms
Vitamin K
• Chief functions in the body
– Synthesis of blood-clotting proteins and bone proteins that regulate blood
calcium
– Given to newborns to prevent hemorrhaging (bleeding)
– Figure 11-13
• Significant sources (lecture slide)
• Deficiency symptoms
–