1. PHYSIOLOGY OF NUTRITION AND VITAMINS MUDr. Romana Šlamberová, Ph.D.

2. 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.energynutritionanimalplant 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.biochemicalchemical compounds This includes the biosynthesis of complex organic molecules (anabolism) and their breakdown (catabolism).anabolismcatabolism

3. 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.gJ 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.kgkJ The amount of food energy in a particular food could be measured by calorimetry.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.d

4. Calorimetry Calorimetry is the science of measuring the heat of chemical reactions or physical changes.heat chemical reactionsphysical 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.heat Direct calorimetry = oxidation of substances in calorimeter or change of water temperature induced by a body Indirect calorimetry = measuring products of biological oxidations (CO 2, H 2 O, final products of protein catabolism) or consumption of O 2 (4,82 kcal freed energy / 1 litre of O 2 ).

5. Indirect calorimetry The Respiratory Quotient is used in BMR calculations (basal metabolic rate) and is a form of indirect calorimetry.calorimetry RQ = CO 2 produced / O 2 consumed 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.

6. 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 < 20 underweight 20 - 25 normal weight 25 - 30 overweight – 1 st degree (light) obesity 30 - 40 2 nd degree (significant) obesity > 40 3 rd degree (malignant) obesity

8. 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.appetitemetabolism 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

9. 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

10. 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.fatty tissue Excessive body weight has been shown to correlate with various important diseases, particularly cardiovascular disease, Diabetes mellitus type 2, sleep apnea and osteoarthritis.cardiovascular diseaseDiabetes mellitus type 2sleep apnea osteoarthritis Not only percentage of fat in the body but also the WHR = waist hip ratio is important Abdominal (men’s) type of obesity (like apple) = high risk for most of the diseases WHR men > 0.95 WHR women > 0.85 Gynoid (women’s) type of obesity (like pear) = lower risk

11. BMI > 30

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

13. 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: psychologicalbinge eating vomiting inappropriate use of laxatives, enemas, diuretics or other medicationlaxativesenemasdiureticsmedication excessive exercisingexercising fasting

14. 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

15. 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.

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

17. 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)vitamins 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 < 5.2 mmol/l triacylglycerols < 1.7 mmol/l LDL < 3.9 mm/l HDL > 0.9 mmol/l

18. 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)

19. 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)

20. Vitamins (1) The word vitamine was coined by the Polish biochemist Casimir Funk in 1912.Polish biochemistCasimir Funk1912 Vita in Latin is life and the -amine suffix is for amine; at the time it was thought that all vitamins were amines. amine 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.

21. 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).

22. 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)

23. Fat soluble vitamins Vitamin A – Retinol Vitamin D Vitamin D2 - Ergocalciferol Vitamin D3 - Cholecalciferol Vitamin E - Tocopherol Vitamin K Attention! Risk of hypervitaminosis!

24. 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.rhodopsinepithelial cellslycoproteinlymphocytesT-cellshaemopoiesishuman growth hormone Deficiency disease:Night blindness, blindness by making the cornea very dry and damaging the retina, immunodeficiency, abnormalities in iron metabolism.Night blindnesscornearetinairon metabolism Hypervitaminosis: 7.5 mg or higher dose. High levels of carotene are not toxic.

25. Vitamin A toxicity Livers of certain animals, especially those adapted to polar environments (polar bears) contain toxic dose of vitamin A. Livers 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. Xavier MertzSwissAntarctic Vitamin A supply: Osteoporosis Lung cancer Teratological effects

26. 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?

27. 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.cholesterol 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.calcitriol kidneys 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

28. 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.carboxylationglutamate 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.intestines 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

29. 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.hydroxylation collagenconnective tissue Strong antioxidant.antioxidant Required for synthesis of dopamine, noradrenaline and adrenaline in the nervous system or in the adrenal glands.dopaminenoradrenalineadrenaline Vitamin C is also needed to synthesize carnitine, important in the transfer of energy to the cell mitochondria.carnitinemitochondria

30. Vitamin C (2) Deficiency disease: Scurvy loose teeth superficial bleeding fragility of blood vessels poor healing compromised immunity mild anemia Hypervitaminosis: Not known

31. 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.

32. Beri-Beri In people whose staple diet consists mainly of polished white rice, which contains little or no thiamine. white rice 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.edema may cause heart failure and death.heart failuredeath

33. 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.cataracts

34. Vitamin B-2 (2) Deficiency disease: leasion of GIT mucous (glossitis, stomatitis, corner of mouth, cheilitis) skin diseases (dermatitis) Hypervitaminosis: Not known

35. 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.NADH Deficiency disease: mild deficiency slows down the metabolism, which in turn decreases cold tolerance and is a potential contributing factor towards obesity.metabolismobesity 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.niacinproteintryptophan Hypervitaminosis: 2,500 mg or higher dose. Symptoms: High blood pressure, low blood cholesterol levels

36. Vitamin B-5 Chemical Name: Pantothenic acid Solubility: Water Daily dose: 10 mg Source: Plants: yeast, whole grain cereals Animals: eggs, liver Function:Part of CoA. Necessary for breaking down carbohydrates, proteins, and fats. carbohydratesproteinsfats Deficiency disease: allergies (e.g. stuffed or runny nose), adrenal insuffiency (Addison's disease) and rheumatoid arthritis. Dermatitis, enteritis, alopecia.allergies adrenalrheumatoid arthritis Hypervitaminosis: Not known

37. 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.proprioception

38. 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.catalysisfatty acidsgluconeogenesis 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

39. 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.red blood cells 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.

40. 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. intrinsic factorvitamin B12 Malabsorption in terminal ileum, demyelination of periferal nerves. Hypervitaminosis: Now known