PHYSIOLOGY OF NUTRITION AND VITAMINS

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PHYSIOLOGY OF NUTRITION AND VITAMINS

• MUDr. Romana Šlamberová, Ph.D.

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Nutrition

• Food is any substance that can be consumed.
• Food is the main source of energy and of
  nutrition, and is usually of animal or plant
  origin.
• Food is a source of substances that are not
  energy and nutrient supply, but are esencial for
  our life (vitamins, salts, trace elements).
• Metabolism (change) is the biochemical
  modification of chemical compounds in living
  organisms and cells.
• This includes the biosynthesis of complex organic
  molecules (anabolism) and their breakdown
  (catabolism).

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Calorie

• A calorie is a unit of measurement for energy.
• The small calorie or gram calorie approximates
  the energy needed to increase the temperature of
  1 g of water by 1 C. This is about 4.185 J.
• The large calorie or kilogram calorie approximate
  the energy needed to increase the temperature of
  1 kg of water by 1 C. This is about 4.185 kJ,
  and exactly 1000 small calories.
• The amount of food energy in a particular food
  could be measured by calorimetry.
• Recommended daily energy intake values for young
  adults are 2500 kcal/d (10 MJ/d, 120 W) for men
  and 2000 kcal/d (8 MJ/d, 100 W) for women.
  Children, sedentary and older people require less
  energy, physically active people more.

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Calorimetry

• Calorimetry is the science of measuring the heat
  of chemical reactions or physical changes.
• Energy moving from one place to another is called
  heat and calorimetry uses the measurement of
  temperature changes to track the movement of
  heat.
• Direct calorimetry oxidation of substances in
  calorimeter or change of water temperature
  induced by a body
• Indirect calorimetry measuring products of
  biological oxidations (CO2, H2O, final products
  of protein catabolism) or consumption of O2
  (4,82 kcal freed energy / 1 litre of O2).

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Indirect calorimetry

• The Respiratory Quotient is used in BMR
  calculations (basal metabolic rate) and is a form
  of indirect calorimetry.
• RQ CO2produced / O2consumed
• RQ carbohydrates 1
• RQ lipids 0,7
• RQ proteins 0,8
• Basal metabolic rate (BMR), is the rate of
  metabolism that occurs when an individual is at
  rest in a warm environment and is in the post
  absorptive state, and has not eaten for at least
  12 hours.
• BMR 2000 kcal/day (during sleep even lower)
• The release of energy in this state is only
  sufficient for the vital organs.
• BMR decreases with age and with the loss of body
  mass. Regular cardiovascular exercise can
  increase BMR. Other factors can also affect BMR,
  such as illness, previous food, environmental
  temperature, and stress levels.

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Body Mass Index

• Energy balance balance between intake and
  dispensation of energy
• Negative consumption of inner supplies
• Positive storage to inner supplies
•  
• BMI body mass index weight (kg) / height
  squared (m)2
• lt 20 underweight
• 20 - 25 normal weight
• 25 - 30 overweight 1st degree (light) obesity
• 30 - 40 2nd degree (significant) obesity
• gt 40 3rd degree (malignant) obesity

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Intake control

• Two areas in the hypothalamus
• Centre of fullness (ventromedial nucleus) if it
  is activated, no need of food intake
• Centre of hunger (lateral nucleus) if it is
  activated, need of food intake
• Hormones
• Leptin is protein hormone that plays a key role
  in regulating energy intake. Leptin is released
  by fat cells in amounts body fat stores. Thus,
  circulating leptin levels give the brain
  (hypothalamic centers) information about energy
  storage for the purposes of regulating appetite
  and metabolism.
• Orexin (hypocretin) is hormone that was suggested
  to be primarily involved in the stimulation of
  food intake. Now it is know that it is also
  responsible for sleep (its dysregulation causes
  narcolepsy).
• Disorders obesity or cachexia

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Factors affecting food intake

• Activation or inhibition of hypothalamic food
  intake centers
• Information from the stomach few hours after
  emptying stomach spontaneous hungry
  contractions appear
• Surrounding temperature cold stimulates
  feeling of hunger, warm inhibits it
• Body temperature after meal body temperature
  increases and decreases appetite and induce
  feeling of fullness.
• Glycostatic cells in the hypothalamus register
  level of glycemia. Decrease of glycemia
  stimulates centre of hunger, increase of glycemia
  inhibits it.
• Other regions of the CNS cortex conditioned
  reflex (perception of aroma, form), tradition,
  time schedule
• Total energy situation of organism decrease of
  supplies and increase of appetite after sport,
  hard work

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Obesity

• Obesity is a condition where the natural energy
  reserve, stored in the fatty tissue is increased
  to a point where it is thought to be a
  significant risk factor for certain health
  conditions as well as increased mortality.
• Excessive body weight has been shown to correlate
  with various important diseases, particularly
  cardiovascular disease, Diabetes mellitus type 2,
  sleep apnea and osteoarthritis.
• Not only percentage of fat in the body but also
  the WHR waist hip ratio is important
• Abdominal (mens) type of obesity (like apple)
  high risk for most of the diseases
• WHR men gt 0.95
• WHR women gt 0.85
• Gynoid (womens) type of obesity (like pear)
  lower risk

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BMI gt 30
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Anorexia

• Anorexia nervosa is an eating disorder
  characterized by voluntary starvation involving
  psychological and sociological components.
• Symptoms
• Refusal to maintain body weight at or above a
  minimally normal weight for age and height (less
  than 85 of that expected, BMI lt 17.5).
• Intense fear of gaining weight or becoming fat.
• Amenorrhea (the absence of at least three
  consecutive menstrual cycles).
• Treatment hospitalization, psychotherapy,
  collaboration with family

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Bulimia

• Bulimia nervosa is an eating disorder. It is a
  psychological condition in which the subject
  engages in recurrent binge eating followed by the
  following activities in order to compensate for
  the food intake and prevent weight gain
• vomiting
• inappropriate use of laxatives, enemas, diuretics
  or other medication
• excessive exercising
• fasting

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Water intake control

• Centers in the hypothalamus near to the
  paraventricular nucleus
• Centre of thirst
• Regulation osmoreceptors activated based on
  the osmotic changes in the body
• hypertonic environment induces feeling of thirst
• hypotonic the opposite
• Role of ADH, Aldosterone and others

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Monitoring of food intake

• Quantitative point of view energy from food
  intake should be the same as energy consumption
• Qualitative point of view ratio of food
  components has to correspond to demand of the
  body (with respect of the age, work, climatic
  conditions, etc.)
• Carbohydrates - 50 80
• Lipids - 20-30
• Proteins - 10-15
• During starvation 70-80 of glucose needed for
  the brain, the rest erythrocytes. Muscles use
  fatty acids.

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Carbohydrates

• Function important storage and transport form of
  energy.
• Low carbohydrates intake Very low carbohydrate
  diets can slow down brain and neural function
  (the nervous system especially relies on
  glucose).
• High carbohydrates intake Diabetes mellitus

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Lipids

• Function
• Cell membrane structure
• Energy storage
• Important for some vitamins (absorption and
  metabolism of vitamins soluble in fat butter
  important source of vitamin A)
• Essential lipids Arachidonic acid, Linoleic acid
  and Linolenic acid (mostly in vegetal oils
  include important fosfolipids)
• Low lipid intake
• missing essential lipids
• hypovitaminosis
• High lipid intake Hyperlipidemia risk of
  cardiovascular diseases
• Normal cholesterol lt 5.2 mmol/l
• triacylglycerols lt 1.7 mmol/l
• LDL lt 3.9 mm/l
• HDL gt 0.9 mmol/l

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Proteins (1)

• Function proteins are involved in functions
  controling almost all the molecular processes of
  the body (enzymes, hormones, structural proteins,
  antibodies etc.).
• Essential aminoacids leucine, isoleucine,
  valine, methionine, phenylalanine, lysine,
  threonine, tryptophan.
• Semiessential aminoacis histidine, arginine
  (during growing), tyrosine (during kidney failure
  not formation from phenylalanine).
• Nitrogen balance protein intake and excretion
• Positive nitrogen balance Higher intake (kidney
  load)
• Optimal protein intake 0.8 g / kg (in children
  and pregnant women 1.3-2.0 g/kg)

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Proteins (2)

• Low protein intake
• Marasmus insufficient amount of food with
  balanced composition
• Extremely decreased lipid storage in the body,
  muscle atrophy ("autocannibalism") and body
  weight less than 80 of normal
• Kwashiorkor type of childhood malnutrition
  caused by inadequate protein intake in the
  presence of fairly good total calorie intake.
• Low oncotic pressure ascites
• Secundar hypoproteinemia Insufficient
  carbohydrate intake (gluconeogenesis), cirrhosis
  (albumin insufficiency), kidney failure (lost of
  proteins), malabsorption (absorption disorder)
• High protein intake (more than 1.5 2.0
  g/kg/day)
• Kidney overload, increased blood pressure (salty
  sausages)

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Vitamins (1)

• The word vitamine was coined by the Polish
  biochemist Casimir Funk in 1912.
• Vita in Latin is life and the -amine suffix is
  for amine at the time it was thought that all
  vitamins were amines.
• A vitamin is an organic molecule required by a
  living organism in small amounts for proper
  health.
• An organism deprived of all sources of a
  particular vitamin will eventually suffer from
  disease symptoms specific to that vitamin
  Avitaminosis.

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Vitamins (2)

• Avitaminosis is any disease caused by chronic or
  long-term vitamin deficiency or caused by a
  defect in metabolic conversion.
• Hypervitaminosis is the syndrome of symptoms
  caused by over-retention (mostly of fat-soluble
  vitamins) in the body, which can lead to toxic
  symptoms.
• In humans, there are thirteen vitamins, divided
  into two groups, the four fat soluble vitamins
  (A, D, E and K) and the nine water soluble
  vitamins (eight B vitamins and vitamin C).

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Water soluble vitamins

• Vitamin C - Ascorbic acid
• Vitamins B
• Vitamin B-1 (Thiamine)
• Vitamin B-2, also Vitamin G (Riboflavin)
• Vitamin B-3, also Vitamin P or Vitamin PP
  (Niacin)
• Vitamin B-5 (Pantothenic acid)
• Vitamin B-6 (Pyridoxine and Pyridoxamine)
• Vitamin B-7, also Vitamin H and Vitamin B-w
  (Biotin)
• Vitamin B-9, also Vitamin M and Vitamin B-c
  (Folic acid) - important for pregnancies
• Vitamin B-12 (Cyanocobalamin)

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Fat soluble vitamins

• Vitamin A Retinol
• Vitamin D
• Vitamin D2 - Ergocalciferol
• Vitamin D3 - Cholecalciferol
• Vitamin E - Tocopherol
• Vitamin K
• Attention!
• Risk of hypervitaminosis!

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Vitamin A

• Chemical Name Retinol
• Solubility Fat
• Daily dose 620µg
• Source
• Plants green vegetable, darkly colored fruits
• Animals milk, liver, eggs, fish oil
• Function Antioxidant. Production of rhodopsin
  (visual pigment), essential for the correct
  functioning of epithelial cells, glycoprotein
  synthesis, involved in maintaining healthy
  lymphocytes and T-cells, needed for normal
  haemopoiesis, production of human growth hormone.
  
• Deficiency diseaseNight blindness, blindness by
  making the cornea very dry and damaging the
  retina, immunodeficiency, abnormalities in iron
  metabolism.
• Hypervitaminosis 7.5 mg or higher dose. High
  levels of carotene are not toxic.

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Vitamin A toxicity

• Livers of certain animals, especially those
  adapted to polar environments (polar bears)
  contain toxic dose of vitamin A.
• Xavier Mertz, a Swiss scientist who died in
  January 1913 on an Antarctic expedition that had
  lost its food supplies and fell to eating its
  sled dogs.
• Vitamin A supply
• Osteoporosis
• Lung cancer
• Teratological effects

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Vitamin E

• Chemical Name Tocopherol
• Solubility Fat
• Daily dose 12 mg
• Source
• Plants Vegetable oils, nuts, green leafy
  vegetables
• Animals milk, eggs, meat
• Function Antioxidant. Vitamin E is often used in
  skin creams and lotions because it is believed to
  play a role in encouraging skin healing and
  reducing scarring after injuries such as burns.
• Deficiency disease
• Persons who cannot absorb dietary fat, has been
  found in premature, very low birth weight infants
  
• Individuals who cannot absorb fat may require a
  vitamin E supplement because some dietary fat is
  needed for the absorption of vitamin E from the
  gastrointestinal tract.
• Muscle dystrophy, sterility.
• Hypervitaminosis 4,000 mg or higher dose, not
  clear yet. May have anticoagulant effect and
  increase the risk of bleeding problems?

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Vitamin D

• Chemical Name D3 cholecalciferol
• Solubility Fat
• Daily dose 2 µg for all Vitamin D
• Source fish oil, fish liver
• It is made in the skin when cholesterol reacts
  with ultraviolet light in the skin.
• Function The most active form of the vitamin is
  calcitriol, a potent steroid hormone. Calcitriol
  is synthesized from calcidiol in the kidneys to
  perform its endocrine function of maintaining the
  calcium metabolism.
• Deficiency disease
• Rickets (kids) bone pain, slowed growth, dental
  problems, muscle loss and increased risk of
  fractures.
• Osteomalacia (adults) lack of calcium results
  in bone fragility
• In certain parts of the world, particularly at
  higher latitudes, total vitamin D input is
  usually not sufficient, especially in the winter
  (milk with D2 or D3)
• Hypervitaminosis 1,250 mg or higher dose,
  hypercalcemia, atherosclerosis

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Vitamin K

• Chemical Name Naphthoquinone
• Solubility Fat
• Daily dose 75 µg
• Source vegetables
• Function
• Involved in the carboxylation of certain
  glutamate residues in proteins to form
  gamma-carboxyglutamate residues.
• blood coagulation (prothrombin-factor II, factors
  VII, IX, X)
• bone metabolism
• vascular biology
• Deficiency disease Bleeding.
• Normally it is produced by bacteria in the
  intestines, and dietary deficiency is extremely
  rare unless the intestines are heavily damaged.
• Vitamin K-deficiency may occur by disturbed
  intestinal uptake (such as would occur in a bile
  duct obstruction), by therapeutic or accidental
  intake of vitamin K-antagonists
• Hypervitaminosis GIT disorders, increased
  coagulation - anemia

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Vitamin C (1)

• Chemical Name Ascorbic acid
• Solubility Water
• Daily dose 75 mg
• Source
• Plants Citrus fruits (orange, lemon, grapefruit,
  lime), tomatoes, potatoes, cabbage, wild roses
• Function
• Participation in hydroxylation, vitamin C is
  needed for the production of collagen in the
  connective tissue.
• Strong antioxidant.
• Required for synthesis of dopamine, noradrenaline
  and adrenaline in the nervous system or in the
  adrenal glands.
• Vitamin C is also needed to synthesize carnitine,
  important in the transfer of energy to the cell
  mitochondria.

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Vitamin C (2)

• Deficiency disease Scurvy
• loose teeth
• superficial bleeding
• fragility of blood vessels
• poor healing
• compromised immunity
• mild anemia
• Hypervitaminosis Not known

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Vitamin B-1

• Chemical Name Thiamine or thiamin
• Solubility Water
• Daily dose 1 mg
• Source
• Plants yeast, pulse, cereal
• Animals liver
• Function Cofactor in decarboxylation processes.
• Deficiency disease Beri-beri, GIT disorders
  (anorexia, nausea, vomiting), tiredness,
  weakness, PNS disorders (paresthesia,
  coordination disorders), psychic disorders
  (depression, irritation, disorders in memory and
  coordination).
• Hypervitaminosis Not known.

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Beri-Beri

• In people whose staple diet consists mainly of
  polished white rice, which contains little or no
  thiamine.
• Disease of nervous system
• Symptoms
• weight loss, emotional disturbances, impaired
  sensory perception (Wernicke's encephalopathy),
  weakness and pain in the limbs, and periods of
  irregular heartbeat.
• Swelling of bodily tissues (edema) is common.
• may cause heart failure and death.

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Vitamin B-2 (1)

• Chemical Name Riboflavin or Vitamin G
• Solubility Water
• Daily dose 1.1 mg
• Source
• Plants leafy green vegetables, yeast, almonds,
  soybeans
• Animals milk, cheese, liver
• Function
• supports energy production by aiding in the
  metabolising of fats, carbohydrates, and
  proteins.
• required for red blood cell formation and
  respiration, antibody production, and for
  regulating human growth and reproduction.
• essential for healthy skin, nails, hair growth
  and general good health, including regulating
  thyroid activity.
• helps in the prevention or treatment of many
  types of eye disorders, including some cases of
  cataracts.

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Vitamin B-2 (2)

• Deficiency disease
• leasion of GIT mucous (glossitis, stomatitis,
  corner of mouth, cheilitis)
• skin diseases (dermatitis)
• Hypervitaminosis Not known

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Vitamin B-3

• Chemical Name Niacin or Vitamin P, resp.PP or
  nicotinic acid
• Solubility Water
• Daily dose 12mg
• Source
• Plants yeast, corn
• Animals eggs, liver
• Function its derivatives such as NADH play
  essential role in energy metabolism in cell and
  DNA repair.
• Deficiency disease
• mild deficiency slows down the metabolism, which
  in turn decreases cold tolerance and is a
  potential contributing factor towards obesity.
• Pelagra caused by dietary lack of niacin and
  protein, especially the essential amino acid
  tryptophan. Symptoms red skin lesions, diarrhea,
  dermatitis, weakness, mental confusion, and
  eventually dementia.
• Hypervitaminosis 2,500 mg or higher dose.
  Symptoms High blood pressure, low blood
  cholesterol levels

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Vitamin B-5

• Chemical Name Pantothenic acid
• Solubility Water
• Daily dose 10 mg
• Source
• Plants yeast, whole grain cereals
• Animals eggs, liver
• FunctionPart of CoA. Necessary for breaking down
  carbohydrates, proteins, and fats.
• Deficiency disease allergies (e.g. stuffed or
  runny nose), adrenal insuffiency (Addison's
  disease) and rheumatoid arthritis. Dermatitis,
  enteritis, alopecia.
• Hypervitaminosis Not known

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Vitamin B-6

• Chemical Name Pyridoxine
• Solubility Water
• Daily dose 1.1 mg
• Source
• Plants yeast, whole grain cereals
• Animals liver
• Function Balancing of Na and K, promoting red
  blood cell production. It is linked to cancer
  immunity and helps fight the formation of
  homocysteine. Helps children with learning
  difficulties, may prevent dandruff, eczema, and
  psoriasis. Helps balance hormonal changes in
  women.
• Deficiency disease Anemia, nerve damage,
  seizures, skin problems, and sores in the mouth.
  Pyroluria.
• Hypervitaminosis 400 mg or higher dose. Causes
  temporary deadening of certain nerves
  (proprioceptory nerves) and feeling of
  disembodiment common with the loss of
  proprioception.

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Vitamin B-7

• Chemical Name Biotin or Vitamin H
• Solubility Water
• Daily dose 30 µg
• Source
• Plants yeast
• Animals seafood, liver, kidneys, milk, eggs
• Function Important in the catalysis of essential
  metabolic reactions to synthesize fatty acids, in
  gluconeogenesis, and to metabolize leucine.
• Deficiency disease Hair loss which progresses in
  loss of eye lashes and eye brows. Dry skin,
  seborrheic dermatitis, fungal infections. Changes
  in mental status, depression, generalized
  muscular pains (myalgias), hyperesthesias and
  paresthesias
• Hypervitaminosis Not known

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Vitamin B-9

• Chemical Name Folic acid or Vitamin M
• Solubility Water
• Daily dose 320 µg
• Source Green vegetable, fruits, cereals
• Function Production and maintenance of new cells
  (especially during infancy and pregnancy),
  necessary for replicating DNA and synthesizing
  RNA. Both adults and children need folate to make
  normal red blood cells and prevent anemia.
• Deficiency disease
• Diarrhea, loss of appetite, weight loss,
  weakness, sore tongue, headaches, heart
  palpitations, irritability, and behavioral
  disorders.
• Hypervitaminosis 1,000 µg or higher dose. Low
  risk - may shade the B12 deficiency.

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Vitamin B-12

• Chemical Name Cyanocobalamin
• Solubility Water
• Daily dose 2 µg
• Source
• Plants breakfast cereals (only source for
  vegetarians)
• Animals Liver, shellfish, eggs, milk
• Function coenzyme in metabolism of aminoacids,
  stimulates erytropoesis
• Deficiency disease
• Megaloblastic anemia inadequate intake of B12
• Pernicious anemia autoimmune anemia (antibodies
  are directed against intrinsic factor). Intrinsic
  factor is required for vitamin B12 absorption, so
  impaired absorption of vitamin B12 can result.
  The term pernicious anemia is sometimes used more
  loosely to include non-autoimmune causes of
  vitamin B12 deficiency.
• Malabsorption in terminal ileum, demyelination of
  periferal nerves.
• Hypervitaminosis Now known