Physiology of nutrition and vitamins
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PHYSIOLOGY OF NUTRITION AND VITAMINS. MUDr. Romana Šlamberová, Ph.D. 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.

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Physiology of nutrition and vitamins


MUDr. Romana Šlamberová, Ph.D.


  • 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).


  • 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.


  • 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).

Indirect calorimetry
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.

Body mass index
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 – 1st degree (light) obesity

    • 30 - 40 2nd degree (significant) obesity

    • > 40 3rd degree (malignant) obesity

Intake control
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

Factors affecting food intake
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


  • 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 theWHR = 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


  • 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 < 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


  • 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

Water intake control
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

    • hypertonicenvironment induces feeling of thirst

    • hypotonic the opposite

  • Role of ADH, Aldosterone and others

Monitoring of food intake
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.


  • 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


  • 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 acidand 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

Proteins 1
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)

Proteins 2
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)

Vitamins 1
Vitamins (1)

  • The word vitamine was coined by the PolishbiochemistCasimir Funk in 1912.

  • Vitain 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.

Vitamins 2
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(mostlyof 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).

Water soluble vitamins
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)

Fat soluble vitamins
Fat soluble vitamins

  • Vitamin A – Retinol

  • Vitamin D

    • Vitamin D2 - Ergocalciferol

    • Vitamin D3 - Cholecalciferol

  • Vitamin E - Tocopherol

  • Vitamin K


    Risk of hypervitaminosis!

Vitamin a
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 disease:Night 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.

Vitamin a toxicity
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

Vitamin e
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?

Vitamin d
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

Vitamin k
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

Vitamin c 1
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.

    • Strongantioxidant.

    • 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.

Vitamin c 2
Vitamin C(2)

  • Deficiency disease: Scurvy

    • loose teeth

    • superficial bleeding

    • fragility of blood vessels

    • poor healing

    • compromised immunity

    • mild anemia

  • Hypervitaminosis: Not known

Vitamin b 1
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.

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.

Vitamin b 2 1
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.

Vitamin b 2 2
Vitamin B-2 (2)

  • Deficiency disease:

    • leasion of GIT mucous (glossitis, stomatitis, corner of mouth, cheilitis)

    • skin diseases (dermatitis)

  • Hypervitaminosis: Not known

Vitamin b 3
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

Vitamin b 5
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.

  • Deficiency disease:allergies (e.g. stuffed or runny nose), adrenal insuffiency (Addison's disease) and rheumatoid arthritis. Dermatitis, enteritis, alopecia.

  • Hypervitaminosis: Not known

Vitamin b 6
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.

Vitamin b 7
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

Vitamin b 9
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.

Vitamin b 12
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