Vitamins
Vital amines – “vital to life” (1900s)Their deficiency attests to their importance
Three new columns added to the Vitamins table on the web
http://www.iom.edu/Object.File/Master/7/296/0.pdfhttp://arbl.cvmbs.colostate.edu/hbooks/pathphys/
misc_topics/vitamins.html
The Vitamins• 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.
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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)
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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
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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
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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
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The Vitamins
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The Vitamins
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The Water-Soluble Vitamins
B Vitamins and
Vitamin C
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Metabolic Pathways Involving B Vitamins
NiacinB6
ThiaminRiboflavin
Pantothenic acid
Folate
Riboflavin
The B Vitamins• Coenzymes
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Thiamin
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• Other names: Vitamin B1
• 1998 RDA – men: 1.2 mg/day– women: 1.1 mg/day
• 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
Thiamin
• Significant sources– Whole grain, fortified, or
enriched grain products– Moderate amounts in all
nutritious food– Pork
• Easily destroyed by heat
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Thiamin
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• Deficiency disease– Beriberi
• Wet, with edema• Dry, with muscle wasting
• Deficiency symptoms– Enlarged heart, cardiac failure– Muscular weakness – Apathy, poor short-term memory,
confusion, irritability – Anorexia, weight loss
• Toxicity symptoms: none reported
Riboflavin
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Riboflavin• Other names: Vitamin B2
• 1998 RDA– Men: 1.3 mg/day– Women: 1.1 mg/day
• 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
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Riboflavin
• Significant sources– Milk products (yogurt,
cheese)– Enriched or whole grains– Liver
• Easily destroyed by ultraviolet light and irradiation
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Riboflavin
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• Deficiency disease: ariboflavinosis• Deficiency symptoms
– Inflamed eyelids and sensitivity to light, reddening of cornea
– Sore throat– Cracks and redness at corners of
mouth– Painful, smooth, purplish red tongue– Inflammation characterized by skin
lesions covered with greasy scales
• Toxicity symptoms: none reported
Niacin
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• Other names– Nicotinic acid– Nicotinamide– Niacinamide
– Vitamin B3
• Precursor: dietary tryptophan• 1998 RDA
– Men: 16 mg NE/day– Women: 14 mg NE/day
• Upper level for adults: 35 mg/day
Niacin
• Chief functions in the body– Part of coenzymes NAD
(nicotinamide adenine dinucleotide) and NADP (its phosphate form) used in energy metabolism
• Significant sources– Milk, eggs, meat, poultry, fish– Whole-grain and enriched breads
and cereals– Nuts– All protein-containing foods
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Niacin
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• Deficiency disease: pellagra• Deficiency symptoms
– Diarrhea, abdominal pain, vomiting– Inflamed, swollen, smooth, bright red tongue– Depression, apathy, fatigue, loss of memory,
headache– Bilateral symmetrical rash on areas exposed to
sunlight
• Toxicity Symptoms– Painful flush, hives, and rash (“niacin flush”)– Excessive sweating– Blurred vision– Liver damage, impaired glucose tolerance
Biotin• 1998 adequate intake (AI)
– Adults: 30 g/day
• Chief functions in the body– Part of a coenzyme used in energy
metabolism, fat synthesis, amino acid metabolism, and glycogen synthesis
• Significant sources– Widespread in foods– Organ meats, egg yolks, soybeans, fish, whole
grains– Raw egg yolks have avidin which binds up
biotin making it unavailable– Also produced by GI bacteria
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Biotin
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• Deficiency – Rare– Seen in adults that are fed artificially by vein
without biotin supplementation – Caused by long term alcohol abuse– Can be induced by feeding people raw eggs
(avidin)
• Deficiency symptoms– Depression, lethargy, hallucinations, numb or
tingling sensation in the arms and legs– Red, scaly rash around the eyes, nose, and mouth– Hair loss
• Toxicity symptoms: none reported
Pantothenic Acid
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• 1998 adequate intake (AI)– Adults: 5 mg/day
• Chief functions in the body– Part of coenzyme A, used in energy
metabolism
• Significant sources– Widespread in foods– Organ meats, mushrooms, avocados,
broccoli, whole grains
• Easily destroyed by food processing
Pantothenic Acid
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• Deficiency symptoms– Vomiting, nausea, stomach cramps– Insomnia, fatigue, depression,
irritability, restlessness, apathy– Hypoglycemia, increased sensitivity to
insulin
• Toxicity symptoms: none reported
Vitamin B6
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• Other names– Pyridoxine– Pyridoxal– Pyridoxamine
• 1998 RDA– Adults (19-50 years): 1.3 mg/day
• Upper level for adults: 100 mg/day• Stored extensively in muscle tissue
(unlike other water soluble vitamins)
Vitamin B6
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• 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
Vitamin B6
• Significant sources– Meats, fish, poultry– Potatoes, legumes,
noncitrus fruits– Fortified cereals– Liver– Soy products
• Deficiency symptoms– Scaly dermatitis– Anemia (small-cell type)– Depression, confusion,
abnormal brain wave pattern, convulsions
– One cause is INH (TB drug)
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Vitamin B6
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• Toxicity symptoms– Depression, fatigue, irritability,
headaches– Nerve damage causing numbness and
muscle weakness leading to an inability to walk and convulsions
– Skin lesions
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Folate
• Absorption
• Folate is absorbed efficiently from fortified products
• Too much folate Copyright 2005 Wadsworth Group, a division of Thomson Learning
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Folate
• Absorption– Folate is absorbed efficiently from
fortified products– Neural tube defects (spina bifida) in
babies born to women with folate deficiency
– Deficiency takes effect early on in pregnancy
– So all women of child bearing age are advised to take folate supplements
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Folate• Activation
– Vitamin B12
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Folate• Recommendations
– Dietary folate equivalents (DFE)
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Folate• Neural tube defects
– Spina bifida
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Folate• Heart disease
– High levels of homocysteine and low levels of folate
• Cancer
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Folate: In Summary
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• Other names– Folic acid– Folacin– Pteroylglutamic acid (PGA)
• 1998 RDA– Adults: 400 g/day
• Upper level for adults: 1000 g/day
Folate: In Summary
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• 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– Fortified grains– Leafy green vegetables, legumes,
seeds– Liver
Folate: In Summary
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• Deficiency symptoms– Anemia (large-cell type)– Smooth, red tongue– Mental confusion, weakness, fatigue,
irritability, headache
• Toxicity symptoms– Masks vitamin B12-deficiency
symptoms
FolateSources
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Vitamin B12
• Activation– Folate
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Vitamin B12
• Absorption– HCl– Pepsin– Intrinsic factor
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Vitamin B12• Deficiency of folate or B12 produces
pernicious anemia
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Vitamin B12: In Summary
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• Other names: cobalamin (and related forms)
• 1998 RDA– Adults: 2.4 g/day
• 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
Vitamin B12: In Summary
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• Significant sources– Animal products (meat, fish, poultry,
shellfish, milk, cheese, eggs)– Fortified cereals
• Easily destroyed by microwave cooking
• Deficiency disease: pernicious anemia
Vitamin B12: In Summary
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• Deficiency symptoms– Anemia (large-cell type)– Fatigue, degeneration of peripheral
nerves progressing to paralysis
• Toxicity symptoms: none reported
Non-B Vitamins• Choline
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Non-B Vitamins• Inositol
– Cell membrane structure• Carnitine
– Transports long chain to the mitochondria for oxidation
• Vitamin imposters– Many of these are included in Vitamin
supplements– Unnecessary since they are available
in foods
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Metabolic Pathways Involving B Vitamins
The B Vitamins• B vitamin deficiencies
– Glossitis– Cheilosis
• B vitamin toxicities
• B vitamin food sources
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Vitamin C
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Vitamin C
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• Other name: ascorbic acid• 2000 RDA
– Men: 90 mg/day– Women: 75 mg/day– Smokers: + 35 mg/day
• Upper level for adults: 2000 mg/day
Vitamin C
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• 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
Vitamin C
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• Significant sources– Citrus fruits– Cabbage-type vegetables, dark green
vegetables (such as bell peppers and broccoli)
– Cantaloupe, strawberries– Lettuce, tomatoes, potatoes– Papayas, mangoes
• Easily destroyed by heat and oxygen
Vitamin C
Sources
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Vitamin C
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• Deficiency disease: scurvy• Deficiency symptoms
– Anemia (small-cell type)– Atherosclerotic plaques– Pinpoint hemorrhages, bone fragility,
joint pain– Poor wound healing, frequent
infections, bleeding gums, loosened teeth
– Muscle degeneration and pain, hysteria, depression, rough skin, blotchy bruises
Vitamin C
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• Toxicity symptoms– Nausea, abdominal cramps, diarrhea– Headache, fatigue, insomnia– Hot flashes, rashes– Interference with medical tests,
aggravation of gout symptoms, urinary tract problems, kidney stones
Vitamin And Mineral Supplements
• Arguments for supplements– Correct overt deficiencies– Improve nutrition status– Reduce disease risks– Support increased nutrient needs– Improve the body’s defenses
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Vitamin And Mineral Supplements
• Who needs supplements?
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Vitamin And Mineral Supplements
• Arguments against supplements– Toxicity– Life-threatening misinformation– Unknown needs– False sense of security– Other invalid reasons
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Vitamin And Mineral Supplements
• Bioavailability
• Antagonistic actions
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Vitamin And Mineral Supplements
• Selection of supplements– Form– Contents– Misleading claims– Cost
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Vitamin And Mineral Supplements
• Regulation of supplements
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An Example of a Supplement Label
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