Download Energy „flow” in the organism

2016.02.26.
Nutrition - vitamins
22.02.2016.
Energy „flow” in the organism
Daily energy expenditure ~ 10.000 KJ (2500 kCal)
PHYSICAL WORK
NUTRIENTS
HEAT PRODUCTION
BREAKDOWN
(CATABOLISM)
WASTE
PRODUCTS
ATP
SYNTHESIS
(ANABOLISM)
BODY COMPOSITION
STORAGE SUBSTANCES
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Energy and substrate „flow” in the organism
Total caloric intake ~ 10.000 KJ (2500 kCal)
PHYSICAL WORK
NUTRIENTS
HEAT PRODUCTION
BREAKDOWN
WASTE
PRODUCTS
SYNTHESIS
ATP
(CATABOLISM)
(ANABOLISM)
BODY COMPOSITION
STORAGE SUBSTANCES
Nutrients
Macronutrients:
Carbohydrates
17,2 kJ/g
Proteins
Fats
17,2 kJ/g
38,9 kJ/g
Utilization of the metabolic energy:
Isodynamic law: for energy purposes different nutrients may replace one another
in accordance with their caloric (energy) values
Max Rubner – (1923)
Supply of precursor molecules for synthetic processes:
The isodynamic law is not fully applicable because of the need of essential food
constituents, which has to be taken up by the food (e.g. essential amino/fatty acids)
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Polar expeditions
PEMMICAN – protein and fat rich
food, originally produced by polar eskimo tribes
100g ~1600 KJ
Traditionally, pemmican was prepared
from the lean meat of large game such
as buffalo, elk or deer. The meat was
cut in thin slices and dried over a slow
fire, or in the hot sun until it was hard
and brittle. Then it was pounded into
very small pieces, almost powder-like
in consistency, using stones. The
pounded meat was mixed with melted
fat with a ratio of approximately 50%
pounded meat and 50% melted fat. In
some cases, dried fruits such as
saskatoon berries, cranberries,
blueberries, or choke cherries were
pounded into powder and then added
(www.wikipedia.de)
to the meat/fat mixture.
Other food constituents (including micronutrients)
Vitamins: vitamins are not energy sources but are essential cofactors in many metabolic
processes. They are not synthetised (or not in sufficient amount) in the human body.
Water
Minerals:
Na+, K+, Ca2+, Mg2+, Cl-, HPO42-
Trace elements: elements which are needed in minute quantities for the proper growth,
development, and physiology of the organism.
iron, iodide, fluoride, copper, managanese, selenium, zinc, chromium,
molibdenium, etc.
Spices:
smell and taste substances – GIT reflexes (secretion, motility)
Fibres:
non-digestable portion of the food (volume – GIT motility)
Additives, breakdown products, etc.
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Carbohydrates
Mono- and disaccharides
Glucose (neurons, erythrocytes – glu-dependent cells)
Sucrose (refined carbohydrates: sweets, soft drinks)
Lactose: milk (human and cow), diary products (lactose intolernce)
Fructose: fruits, juices
Oligosaccharides
Dextrin: e.g.: toast, biscuits
Polysaccharides
Plant origin: starch – cereals, potato, corn, rice, beans
this is the major source of energy in normal nutrition!
cellulose fibers
Animal origin: glycogene
Proteins
To keep a nitrogen balance of the body: ~30 g/day
WHO recommendation: 0.8-1g/kg b.w.
Essential amino acids (there is no de novo synthesis in the human body)
Lys, Trp, Phe, Met, Tre, Leu, Ile, Val
Biological value (BV) of proteins: measure of the proportion of absorbed
protein from a food which becomes incorporated into the proteins of the
organism's body.
Proteins of animal origin – high BV (they contain all of the essential amino
acids, with a nearly optimal composition)
meat (75%), milk, diary products (lactalbumin, lactoglobulin, casein; ~85%),
egg (ovalbumin; 94%), whey protein (~100%!)
Proteins of plant origin: usually lower BV
whole wheat (gliadin, glutein; 52%), beans (soybean; 73%)
But e.g.: corn (zein)– low tryptophan content
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Nitrogen balance of the body
http://www.ucl.ac.uk/~ucbcdab/Nbalance/Nbalance.htm
Explanation of the concept of the biological values of proteins
Type 1. food protein
Proteins of the body
BV = 100%
Type 2. food protein
BV=50%
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B.V. (Biological Value) is the proportion of absorbed protein that is retained
in the body for maintenance and/or growth. The highest score of 100 was
given for the best protein at the time, egg. However, whey protein came
along and proved even better than egg.
P.E.R. (Protein Efficiency Ratio) is the gain in body weight divided by the
weight of the protein consumed.
N.P.U. (Net Protein Utilization) is the proportion of protein intake that is
retained (calculated as BV times Digestibility).
PDCAAS (Protein Digestibility Corrected Amino Acid Score) is based on the
amino acid requirements of humans. A protein scoring a 1.0 indicates it
meets all the essential amino acid requirements of humans according to the
Food Agriculture Organization and World Health Organization
Fat
High energy content
Major sources are triglycerides (glycerol + fatty acids)
Fatty acids
– saturated FAs
- unsaturated FAs– polyunsaturated fatty acids (PUFA): essential FA!!
Cholesterol and cholesterol derivates
Lipid soluble vitamins (A,D,E,K)
Fats of animal origin:
Lard, bacon, butter, etc.; +hidden fat (muscle)
Fats and oils of plant origin:
These are rich in essential fatty acids (PUFA – linolenic acid, arachidonic acid, etc.)
Oily seeds (sunflower, rasp, peanut, olive)
Hardening: saturation of the unsaturated FA with hydrogenation : tarns -UFAs
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Correlation between the serum cholesterol level and the incidence of heart disease
Optimal: < 5.2 mmol/l
Framingham Heart Study – 1949 -
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LDL – cholesterol -- atherosclerosis
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Rules for the optimal daily food intake
1. The energy content of the food should cover the energy expenditure
2. Should contain the minimal daily requirements of proteins, carbohydrates and fats
3. Should also contain the minimal RDAs of vitamins, minerals and trace elements
4. Toxic components should be lower than the upper tolerable limit
Optimal relative proportions of macronutrients to cover daily energy requirements
proteins (ca.: 1 g/kg b.w.)
Pro: nitrogen balance
Con: calorigenic effect
digestibility
carbohydrates
(min. 10%)
Pro: antiketogenic
Con: „empty” calory
15%
25%
fats (1/3 essential FA)
Pro: essential FA, ADEK vits.
Con: „empty” calory
hypercholesteraemia
ketogenic effect
60%
Trace elements
Iron:(12-18 mg/d) – meat, egg, vegetables (spinach, broccoli)
Iodide: (180 - 200 µg/d) – tap water, salt
hypothyroidism, goiter
geographical differences: endemic goiter
Fluoride:(1 mg/d) – tap water supplementation, toothpaste, pills:
+
Selenium
Zinc
Manganese
Molybdenum
etc.
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http://what-when-how.com/molecular-biology/metal-requiringenzymes-molecular-biology/
Food piramyde
Fats, Oils & Sweets
Use Sparingly
Milk, Yogurt,
& Cheese Group
2-3 Servings
Vegetable
Group
3-5 Servings
Meat, Poultry, Fish,
Dry Beans, Eggs,
& Nuts Group
2-3 Servings
Fruit Group
2-4 Servings
Bread,Cereal,
Rice, & Pasta
Group
6-11 Servings
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http://health.gov/dietaryguidelines/2015/guidelines/
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Determination of the ideal body mass
BMI= Body Mass Index (Quetelet index):
body weight (kg)/(body high in meter)2
normal range: 19-25
The ideal body composition (% of the body weight):
extra cellular fluid volume: 15%
total fat content
20%
total muscle content
40%
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Determination of the „Lean Body Mass” value – total fat mass
Thickness of the skin fold (subcutaneous fat layer)
Age
(years)
Women
Men
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Historical background – vitamin research
Sir Frederick Gowland Hopkins: 1861-1947 (Nobel prize 1929)
„Hopkins suspected that minute amounts of unknown, chemicals were necessary in
the diet. He fed mice solely on fat, starch, salts, and purified milk protein (containing all
the essential amino acids). They became sick and ceased to grow. However, when
also given a very small quantity of whole milk, they recovered. This led to the isolation
of types vitamin „B”, and what Hopkins called "fat-soluble A" (actually two vitamins: A
and D).”
Christian Eijkmann and the discovery of the importance
of nutrition and the pathogenesis of Beriberi
(Nobel prize 1929)
Beriberi disease – peripheral neuropathy, pain,
palsy, muscle atrophy, cardivascular complications
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http://www.nobelprize.org/
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Vitamins: vitamins are not energy sources but are essential cofactors in many
metabolic processes. They are not synthesized (or not in sufficient amount) in the
human body.
origin: “Vital amine” - „Vitamine” (Casimier Funk, 1912)
1913 E.V. McCollum: alphabetical nomenclature (A, B, C, D)
1920: Jack Cecil Druommond: „Vitamin” (not all vitamins are „amines”)
•Vital compounds – (long term) deprivation results in symptoms and illnes
•exogenous -”essential” substances (exemptions: vit. D, B3)
•Daily uptake is low (micrograms - 100 mg/d)
•Energy content is not significant – biological function!
Diverse functions of vitamins
• Constituent of enzymes or enzyme complexes
(prostetic groups, co-enzymes)
• Non-enzymatic protein complexes (retinol –
rhodopsin)
• antioxidants: neutralization of reactive oxygen
radicals (vit. A, E, C)
• Signalization: hormone - activated vitamin D
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year
Discovery of vitamins and their chemical structures
vitamin
1909
Vitamin A retinol
1912
Vitamin B1 thiamine
1912
Vitamin C ascorbic acid
1918
Vitamin D calciferol
1920
Vitamin B2 riboflavin
1922
Vitamin E tocopherol
1926
Vitamin B12 cobalamine
1929
Vitamin K phyllochinon
1931
Vitamin B5 pantothenic acid
1931
Vitamin B7 biotin
1934
Vitamin B6 pyridoxin
1936
Vitamin B3 niacin
1941
Vitamin B9 folic acid
Nobel Prize in Phsiology and Medicine
Discovery of Vitamins
Christiaan Eijkman (1929)
Vitamin B1
Sir Frederick Gowland Hopkins (1929) Growth Stimulating Vitamins
George Hoyt Whipple (1934)*
Vitamin B12
George Richards Minot (1934)*
Vitamin B12
William Parry Murphy (1934)*
Vitamin B12
Henrik Carl Peter Dam (1943)
Vitamin K
Isolation of Vitamins
Adolf Otto Reinhold Windaus (1928)* Vitamin D
Albert von Szent-Györgyi Nagyrapolt (1937) Vitamin C
Richard Kuhn (1938)
Vitamin B2 and B6
Edward Adelbert Doisy (1943)
Vitamin K
Nobel Prize in Chemistry
Synthesis of Vitamins
Walter Norman Haworth (1937)
Paul Karrer (1937)
Robert Burns Woodward (1965)*
Vitamin C
Vitamin E
Vitamin B12
Structure of Vitamins
Paul Karrer (1937)
Richard Kuhn (1938)
Lord (Alexander R.) Todd (1957)*
Dorothy Crowfoot Hodgkin (1964)*
Vitamin A and E
Vitamin B2
Vitamin B12
Vitamin B12
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The Nobel Prize in Chemistry 2004 was awarded jointly to Aaron Ciechanover, Avram
Hershko and Irwin Rose "for the discovery of ubiquitin-mediated protein degradation".
MTA (HAS) Inaguration lecture, 2005.(www.videotorium.hu)
Provitamins
Precursors of vitamins which will be converted into biologically
active compounds by the cells of the organism
Examples:
ß-carotin – retinol (vit. A)
D - vitamin:
cholesterol – dehydrocholesterol –cholecalciferol (D3)
ergocalciferol (D2, plant origin)
Hydroxylation: (liver, kidney) - 1,25-dOH-cholecalciferol (active)
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Antivitamins
Compounds having selective antagonistic effects with the biological
actions of vitamins
examples:
vit. K – coumarin derivatives (anticoagulants): warfarin
avidin (egg white) – high affinity binding of biotin (vit. B7)
methotrexat (cytostaticum) – antagonist of folic acid (vit. B9)
– (reduction of the activity of dihydrofolate-reductase)
antidote: supplementation of the corresponding vitamin!
Methotrexat
Folic acid
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RDA – Recommended Daily Allowance
RDA is usually within the mg/d range
exempitons: B12, D: microgram/d range
vit. C .: 75-100 mg/d
IE (IU) – International Unit: vitamin activity is conferred by a
mixture of biologically active substances
Fig. 1. The risks of adverse health effects from decreasing intakes and the risks of
adverse health effects with increasing intakes. The Estimated Average Requirement
(EAR) reflects the intake where 50% of a population group is at risk of inadequacy,
whereas the Tolerable Upper Intake Level (UL) is set an uncertainty factor lower
than the No Observed Adverse Effect Level (NOAEL) or Lowest Observed Adverse
Effect Level (LOAEL). The Recommended Nutrient Intake (RNI) is set at two
standard deviations above the EAR and reflects the intake level at which 2.5% of a
population group is at risk of inadequacy.
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Hypo- or avitaminosis
Avitaminosis is any disease caused by chronic or longterm vitamin deficiency
• RDA is dependent on: age, gender, body weight,
physical activity, stressors, pregnancy, lactation, etc.
• General symptoms: restricted physical and mental
performance
• Sensitive tissues and organs: high metabolic
(myocardium, nervous system, immune system) or
mitotic activity (skin, mucous membrane epithel cells,
bone marrow)
Causes of avitaminosis
•
•
•
•
Decreased intake
Malabsorption
Increased demand
Special conditions:
climatic conditions (UV-irradiation, insolation)
damage of the colonic bacterial flora
lack of prophylaxis
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Vitamin and trace element supply in the female population of Germany
Hypervitaminosis
No-Observed-Adverse-Effect Level (NOAEL)
Lowest-Observed-Adverse-Effect Level (LOAEL)
Tolerable Upper Intake Level (UL)
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Estimated Average
Requirements
Recommended Daily
Allowance
Tolerable Upper Intake Level
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Name
Synonym
Chemical name
Vitamin A
Axerophtol, Retinol
Retinol
Vitamin B1
Aneurin
Thiamine
Vitamin B2
Lactoflavin, Vitamin G
Riboflavin
Vitamin B3
Vitamin PP, Vitamin B5
Niacin
Vitamin B5
Vitamin B3
Pantothenic acid
Vitamin B6
Adermin, Pyridoxol
Pyridoxin, Pyridoxal and Pyridoxamin
Vitamin B7
Vitamin H, I vagy Vitamin Bw
Biotin
Vitamin B9
Vitamin M vagy Vitamin Bc
Folic acid
Vitamin B12
Erythrotin
Cobalamin
Vitamin C
Ascorbic acid
Vitamin D
Calciferol
Vitamin E
Tocopherol
Vitamin K
Phyllochinon and Menachinon
Classification of vitamins
1/ lipid soluble vitamins: A, D, E, K, (F)
•Absorption together with other lipids
•Accumulation and storage in the adipose tissue (large reserves, except: K)
•Blood transport - lipoproteins
•Excretion: bile (liver)
2/ Water soluble vitamins: B-group and vit. C
•Specific (carrier mediated) absorption in the gut
•Restricted reserves (few weeks) – except: B12 - liver
•Excretion: kidney
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A
Retinal pigment
Coenzyme in
B1 (thiamine) decarboxylation of
pyruvate and α-keto acids
Male: 1000 µg
Female: 800 µg
Follicular
hyperkeratosis, night
blindness
Male: 1.5 mg
Female: 1.1 mg
Beriberi
B2
(riboflavin)
Coenzymes FAD and
FMN, H carriers in
mitochondria
Male: 1.7 mg
Female: 1.3 mg
Hyperemia of
nasopharyngeal
mucosa, normocytic
anemia
B3 niacin
(nicotinic
acid)
Coenzymes NAD and
NADP, H carriers in
mitochondria
Male: 19 mg
Female: 15 mg
Pellagra
B6
(pyridoxine)
Coenzyme in
transmination for synthesis
of amino acids
Male: 2 mg
Female: 1.6 mg
Stomatitis, glossitis,
normocytic anemia
B12
(cobalamin)
Coenzyme in reduction of
ribonucleotides to
deoxyribonucleotides.
Promotes formation of
erythrocytes, myelin
2 µg
Pernicious anemia (a
megaloblastic
anemia)
C (ascorbic acid)
Coenzyme in formation of hydroxyproline used in collagen
60 mg
Scurvy
D (1,25-cholecalciferol)
Ca2+ absorption
5-10 µg
Rickets,
osteomalatia
E (α-tocopherol)
Antioxidant: thought to prevent
oxidation of unsaturated fatty acids
Male: 10 mg
Female: 8 mg
Peripheral
neuropathy
K (K1 = phylloquinone,
K2 = various
menaquinones)
Male: 70-80 µg
Clotting: necessary for synthesis by
liver of prothrombin and factors VII, IX Female: 60-65
and X
µg
Hemorrhagic
disease
Folate (B9)
Backbone used to synthesize purines
and thymine
Male: 200 µg
Female: 180 µg
Pregnancy: 400
µg
Megaloblastic
anemia
Biotin (B7)
Coenzyme in carboxylation reactions
30-100 µg*
Neurologic
changes
Pantothenic acid (B5)
Coenzyme A (CoA). Necessary for
carbohydrate and fat metabolism
involving acetyl-CoA; amino acid
synthesis
4-7 mg*
Abdominal
pain, vomiting,
neurologic
signs
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Albert von Szent-Györgyi Nagyrápolt
Nobel Prize - 1937
"for his discoveries in connection with the biological
combustion processes, with special reference to vitamin C and
the catalysis of fumaric acid"
„So the reaction 2H + O = H2O, which seems such a simple one, breaks
down into a long series of separate reactions. With each new step, with each
transfer between substances, the hydrogen loses some of its energy, finally
combining with oxygen in its lowest-energy compound. So each hydrogen
atom is gradually oxidized in a long series of reactions, and its energy released
in stages.”
Nobel lecture: Szent-Györgyi – Krebs – „Half-cycle”
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Vitamin C (ascorbic acid)
Defic.: scurvy, Möller-Barlow disease
Bleedings (blood vessels) , aortic aneurism
immundeficiency
Biological action: proline and lysine hydroxilation
synthesis of collagene
Dopamine hydroxilation (synthesis of cathecolamines)- depression (?)
GIT absorption of iron ions
antioxidant
RDA: 70-100 mg/d
(vegetables, fruits)
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In humans, primates and guinea pigs the enzyme gulonolacton-oxidase is missing
Genetically – there is no endogenous synthesis of Vit. C
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Vitamin A (Axerophthol, Retinol)
RDA: 1,5 mg/d (5000 IE)
(liver, eggs, diary products, oily seeds)
ß-carotin: vegetables
retinol (retinal) – photo pigments (rod- and photopsins)
retinoid receptors – auto- and paracrine effects
protection of the epidermis and mucosal epithelial cells
Deficiency:
•Xerophtalmus, keratomalacia (destruction of the cornea)
•Hemeralopy (decreased dark adaptation, „night blindness”)
•Impaired growth
•Dysfunction of the epithels of the mucous membranes (mucin – ceratin)
•Antioxidant and scavenger function
Hypervitaminosis (dermatitis, hair loss, increased ICP)
Terratogeneic effect – disturbance of the intrauterine development
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Keratomalacia
Vitamin D (anti-rachitis (rickets) vitamin)
RDA: 12 µg/d (500 IE)
(fish oil, diary products, oily seeds)
D2 (ergocalciferol) - plant origin
D3 (cholecalciferol) - animal origin
Active forms: 1,25 dihydroxi-cholecalciferol (kidney, liver)
Biological action: GIT transepithelial transport of Ca2+
(regulation of the expression of Calbindin, Ca++ pumps)
Defic.: rachitis, osteomalacia
D-hypervitaminosis (hypercalcemia)
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Vitamin E
(alpha - tocopherol)
RDA: 10 mg/d
(green vegetables, oily seeds)
Antioxidant – inactivates of the reaktive oxygene radicals
Deficiency:
•Human: less understood - peripheral neuropathy?
•Animal models: sterility, spontaneous abortion
Vitamin K
(phylloquinone, menaquinone)
RDA: 10 µg/d
vegetables, importance of the gut flora
(„microbiome”)
Deficiency: bleedings, impaired bone
development
(Antivitamins: coumarine derivates)
Biological effects:
Vitamin-K dependents coagulation factors II. VII. IX. X.,
protein S and C
Bone formation: – osteokalcin (Gla-protein)
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Free radical mechanism of lipid peroxidation
coumarin
coumarin
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A
Retinal pigment
Coenzyme in
B1 (thiamine) decarboxylation of
pyruvate and α-keto acids
Male: 1000 µg
Female: 800 µg
Follicular
hyperkeratosis, night
blindness
Male: 1.5 mg
Female: 1.1 mg
Beriberi
B2
(riboflavin)
Coenzymes FAD and
FMN, H carriers in
mitochondria
Male: 1.7 mg
Female: 1.3 mg
Hyperemia of
nasopharyngeal
mucosa, normocytic
anemia
B3 niacin
(nicotinic
acid)
Coenzymes NAD and
NADP, H carriers in
mitochondria
Male: 19 mg
Female: 15 mg
Pellagra
B6
(pyridoxine)
Coenzyme in
transmination for synthesis
of amino acids
Male: 2 mg
Female: 1.6 mg
Stomatitis, glossitis,
normocytic anemia
B12
(cobalamin)
Coenzyme in reduction of
ribonucleotides to
deoxyribonucleotides.
Promotes formation of
erythrocytes, myelin
2 µg
Pernicious anemia (a
megaloblastic
anemia)
C (ascorbic acid)
Coenzyme in formation of hydroxyproline used in collagen
60 mg
Scurvy
D (1,25-cholecalciferol)
Ca2+ absorption
5-10 µg
Rickets
E (α-tocopherol)
Antioxidant: thought to prevent
oxidation of unsaturated fatty acids
Male: 10 mg
Female: 8 mg
Peripheral
neuropathy
K (K1 = phylloquinone,
K2 = various
menaquinones)
Clotting: necessary for synthesis by
Male: 70-80 µg
liver of prothrombin and factors VII, IX Female: 60-65
and X
µg
Hemorrhagic
disease
Folate (B9)
Backbone used to synthesize purines
and thymine
Male: 200 µg
Female: 180 µg
Pregnancy: 400
µg
Megaloblastic
anemia
Biotin (B7)
Coenzyme in carboxylation reactions
30-100 µg*
Neurologic
changes
Pantothenic acid (B5)
Coenzyme A (CoA). Necessary for
carbohydrate and fat metabolism
involving acetyl-CoA; amino acid
synthesis
4-7 mg*
Abdominal
pain, vomiting,
neurologic
signs
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(Vitamin F)
Legalább 3.5 %-a az teljes energiabevitelnek
Többszörösen telítetlen zsírsavak
(Poly Unsaturated Fatty Acid; PUFA):
linolsav, linolénsav (esszenciális zsírsavak)
hatása:
Foszfolipid és prosztaglandin szintézis
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Vitamin B1
(thiamin, aneurin)
10mg/nap
előfordulás: húsfélék, teljesőrlésű lisztfélék
termolabilis
piruvát-dehydrogenáz komplex koenzime – dekarboxyláció
hiánybetegség: beri beri (ld. hántolatlan rizs)
Polyneuritis, kardiális tünetek, KIR tünetek
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Vitamin B2
(riboflavin)
1.5 mg/d
előfordulás: tej, hús, tojás, halhús
Termostabil flavin mononukleotid
Flavin Adenine Dinucleotid (FAD), Flavin-Mononucleotid
Proton-elektron transzportfolyamatok koenzime
hiánytünet: száj (nyelv) nyálkahártya gyulladása, fejfájás
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Niacin, nikotinsav, B3
dehidrogenázok koenzime (NADH)
redox folyamatok koenzime
15-30 mg/d
Hiány csak akkor alakul ki, ha a triptofán bevitel is korlátozott
pelle agra (durva bőr, dermatitis), fekete nyelv (glossitis)
3D: Dermatitis, Diarhea (hasmenés)‚ Dementia, (Death)
Előfordul: tej, mogyoró, élesztő
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Vitamin B6 (pyridoxal, pyridoxamin, pyridoxol)
koenzim – amino-transzferázok
Hiány: emberben nagyon ritka
dermatitis, görcsök, émelygés, hányás
előfordulás: hús, máj, élesztő, mogyoró
2.0-2.2 mg/d
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Pantoténsav (B5): CoA- koenzim része
hiány: őszülés,
memória zavarok
Védi a bőrt
10-15 mg
előfordulás: általános
pantotensav
Biotin (H vagy B7 vitamin)
koenzim (biotinil-lizil enzim)
karboxylázok (piruvát dekarboxiláz)
hiánybetegség: dermatitis, neuromuszkuláris zavarok (izomgyengeség)
(nyers tojás fogyasztása: Avidin!)
Napi bevitel: 100 µg
Előfordul: máj, vese, élesztő
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B12 vitamin (cyanocobalamin, antipernicioza vitamin)
hiány: anaemia perniciosa, funikuláris myelosis (hátsókötegi rsz.)
•vérképzés – nukleotid (purine), szintézis (DNA), C1 csoportok szállítása
threonin, valin, isoleucin, methionin anyagcsere
előfordulás: húsfélék, máj
Napi bevitel: 3 µg – (nagy raktárak a májban)
Folsav (B9 vitamin)
(tetrahydrofolsav, FH4)
C-1 csoportok transzportja (nukleutid, aminosav anyagcsere)
hiány: anaemia perniciosa (mint B12 hiány esetén)
Terhesség alatt: csökkenti a velőcső záródási zavarok gyakoriságát
Napi bevitel: 0.3 mg
Előfordulás: máj, növényi levelek (saláta, spenót, brokkoli, stb.)
Antivitamin: Methotrexat (citosztatikum)
Szulfonamidok: para-amino benzoesav analóg - antibakteriális hatásúak
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2016.02.26.
http://www.ucl.ac.uk/~ucbcdab/Nbalance/N
balance.htm
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