Course 1 Nutrition PDF

Physiological bases of nutrition. Digestion and absorption of the main macro- and micronutrients. The main food groups. Course 1 Șef. Lucr. Dr. Luminița Confederat University of Medicine and Pharmacy "Grigore T....

Physiological bases of nutrition. Digestion and absorption of the main macro- and micronutrients. The main food groups. Course 1 Șef. Lucr. Dr. Luminița Confederat University of Medicine and Pharmacy "Grigore T. Popa" Iași Faculty of Medical Bioengineering Specialization: BFKT  Introduction ✔ Nutrition - important role in promoting and maintaining health ✔ The nutritional needs of children are different depending on the age (infant, toddler, teenager) in accordance with the stages of growth and development ✔ In adults, the nutritional needs are different depending on the activity carried out, on the weight status and these shloud be adapted according to the associated diseases ✔ The elderly patient is generally prone to malnutrition, presenting many diseases according to which the diet must be adapted ✔ The processes of industrialization, urbanization and mechanization -> changes in eating habits and a sedentary lifestyle  Introduction ✔ Unhealthy diet – involved in the development of chronic diseases with an increased prevalence such as diabetes, obesity, cardiovascular diseases, cancer, osteoporosis ✔ The target of primary prevention – the control of modifiable risk factors ♦ eating habits ♦ sedentarism ♦ smoking ♦ alcohol consumption Healthy lifestyle  Eating vs. Nutrition ✔ Eating = providing the food for the body through the ingestion of products of animal or vegetable origin ✔ Nutrition = the science that studies the body's needs in energy and nutritional principles necessary for the normal growth and development of children and adolescents and for the maintenance of the adult organism in optimal conditions, depending on: ♦ age ♦ sex ♦ degree of physical activity ♦ environmental conditions ♦ presence of health or disease condition  Eating vs. Nutrition ✔ Nutrition = process through which the body obtains from the external environment a multitude of substances (nutritional principles, nutrients) that are modified in order to: ♦ support vital functions ♦ ensure the development and normal functioning of cells, tissues, organs and systems ♦ obtain the necessary energy for carrying out all activities ✔ Nutrients = the components of food that are metabolized by the body and used by cells ✔ The body uses nutrients continuously, even if the food intake is discontinuous through the storage or release of energy substrates ✔ A variety of foods is necessary to ensure the daily needs in nutrients  Classification of nutrients ✔ Macronutrients = needed by the body in large quantities ♦ carbohydrates ♦ proteins ♦ fats (lipids) ✔ Micronutrients = needed in small amounts, most of them cannot be synthesized by the body ♦ fat-soluble vitamins: A, D, E, K vitamins ♦ water-soluble vitamins: C vitamin (ascorbic acid), vitamins from group B (B1-thiamine, B2-riboflavin, B6- pyridoxine, B9- folic acid, B12- cobalamin) ♦ mineral elements macrominerals: Ca, P, Mg, Na, K, Cl, S microminerals: Fe, Zn, I, Cu, Mn, Cr, Se, F ✔ Water = essential constituent of living organisms, indispensable nutrient  Physiological basis of nutrition Complex food (macronutrients + micronutrients)  carbohydrates  proteins  vitamins  minerals  lipids digestion simple molecules absorption Use at the tissue level  Physiological bases of nutrition ✔ Digestion = biochemical process of breaking down food in the gastrointestinal tract (GIT) under the action of enzymes into simple substances that will be absorbed ✔ Absorption = the transport of nutrients through the cells of the gastrointestinal tract into the blood ✔ Stages: ♦ ingestion: introduction of food into the GIT ♦ propulsion: movement of food through the GIT (swallowing + peristalsis) ♦ mechanical digestion: mastication, kneading in the stomach, segmentation in the small intestine ♦ chemical digestion: the chemical decomposition of food under the action of digestive enzymes ♦ absorption: transport of the end products of digestion into the blood ♦ defecation: the elimination of undigested and unabsorbed substances in the form of faeces  Macronutrients – Carbohydrates ✔ Carbohydrates = organic substances made up of carbon, oxygen and hydrogen atoms ✔ They provides the energy that the body needs for the normal functioning of cells, organs and systems (1 g of carbohydrates – 4 Kcal) Classification of carbohydrates: Simple carbohydrates - fast absorption ✔ Monosaccharides (glucose, fructose, galactose) ✔ Disaccharides (sucrose, lactose, maltose) ♦ food sources: fruits, honey, cereal syrup, beet and sugar cane, fruits and vegetables (sucrose), milk and dairy products (lactose), maltose (cereals and beer) Complex carbohydrates (polysaccharides) - slow absorption ✔ Digestible polysaccharides: starch, glycogen ♦ food sources: starch: cereals, vegetables and legumes (peas, corn, beans, potatoes, lentils), glycogen: meat, fish ✔ Non-digestible polysaccharides (dietary fiber)  Macronutrients– Carbohydrates Dietary fiber: Soluble fiber ✔ Pectins (fast-growing greens, apples, oranges, carrots), gums (beans, oats), mucilages ✔ Bind carcinogens, lower plasma cholesterol, delay gastric emptying, delay digestion and absorption of carbohydrates Insoluble fibers ✔ Cellulose (pulp and peel of fruits and vegetables, nuts, seeds), hemicelluloses (whole grains), lignins (fruit with peel and seeds) ✔ Increase the volume of faeces (useful in constipation), decrease the transit time, decrease the production of free radicals in the digestive tract  Macronutrients – Carbohydrates The role of carbohydrates in the body: ✔ The main source of energy for body cells (1 g of carbohydrates – 4 Kcal) ✔ Protect proteins (they are transformed into carbohydrates when intake is insufficient) ✔ Synthesis of nucleotides and nucleic acids ✔ Normal bowel function Recommendations: ✔ Carbohydrates are at the basis of nutrition - cover 50-65% of the caloric ration / 24 hours ✔ Foods containing simple carbohydrates must be consumed with moderation (they are absorbed quickly, increase blood sugar suddenly and induce the feeling of hunger) ✔ The consumption of complex carbohydrates (vegetables and fruits) is recommended (they are absorbed slowly, increase blood sugar slowly and contain dietary fiber)  Digestion and absoption of carbohydrates ✔ Oral cavity: salivary amylase hydrolyzes starch to dextrins and maltose ✔ Stomach: amylase activity is stopped in contact with HCl ✔ Small intestine: ♦ duodenum: pancreatic amylase breaks down starch into dextrins and maltose ♦ at the brush border level: sucrase, lactase, maltase, isomaltase break down disaccharides into monosaccharides (glucose, galactose and fructose) ✔ Monosaccharides -> capillaries of intestinal villi -> blood current -> portal vein -> liver ✔ Glucose ♦ transported to the tissues ♦ stored in the liver and muscles as glycogen ✔ Fructose and galactose -> converted to glucose in the liver ✔ Non-digestible carbohydrates (food fibers - cellulose, pectins) -> eliminated unmodified  Macronutrients– Proteins ✔ Proteins = complex molecules made up of chains of essential (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine) and non-essential amino acids ✔ Essential constituents of the body with a structural, functional and energetic role Classification of proteins: Depending on the biological value/protein quality: ✔ Complete proteins: contain all essential amino acids in appropriate proportions (meat, fish, eggs, milk, soy) ✔ Partially complete proteins: they contain all amino acids, but not in the required quantity (gliadin from cereals) ✔ Incomplete proteins: missing essential amino acids (cereals and vegetables: flour, rice, millet, pasta, beans, potatoes) Depending on the source: ✔ Animal proteins: meat, eggs, milk ✔ Vegetable proteins: soy, peas, beans, almonds, hazelnuts, nuts, mushrooms  Macronutrients – Proteins The role of proteins in the body: Structural: ✔ Growth and development ✔ Repair and maintenance of body structures Functional ✔ Hormones: insulin, glucagon, thyroid hormones, growth hormone ✔ Enzymes: catalyze biochemical synthesis/degradation reactions in the body ✔ Maintaining the water balance ✔ Maintaining normal pH ✔ Transport: hemoglobin (respiratory gases), plasma lipoproteins (lipids) ✔ Immune role: antibodies ✔ Hemostasis and coagulation Energy: 1 g protein = 4 Kcal  Macronutrients – Proteins Recommendations: ✔ Proteins must cover 12-15% (max 20%) of the daily caloric intake ✔ 0.8 – 1.2 g/kg body ✔ The ratio of animal protein/vegetable protein = 1/1 Animal proteins/ 100 g Vegetable proteins/ 100 g eggs 14 soy, beans 20-23 milk, yogurt 3,5 nuts 14-20 cheese 13-26 mushrooms 2-3 meat, fish 18-24 bread, cereals, 8-10 pasta  Digestion and absorption of proteins ✔ In the stomach: proteins are broken down by pepsin into peptones and large polypeptides ✔ In the duodenum: contact of the chyme with the duodenal mucosa -> activation of enterokinases -> transforms trypsinogen into trypsin -> activates chymotrypsin and carboxypeptidase ✔ Trypsin, chymotrypsin, carboxypeptidase – continue hydrolysis until the formation of small polypeptides (dipeptides, tripeptides) and amino acids ✔ At the brush border: dipeptides and tripeptides are hydrolyzed to amino acids ✔ Amino acids – absorbed through 4 different active transport systems via co-transport with Na -> liver -> released into general circulation  Macronutrients – Lipids ✔ Lipids = complex molecules made up of a polyalcohol and fatty acids ✔ In food and in body tissues, lipids are found in 3 forms: triglycerides (95% of ingested lipids), phospholipids and sterols (cholesterol and phytosterols) Classification of lipids: Simple Triglycerides Glycerol + 3 fatty acids Complex Phospholipids Lecithin, phosphatidyl-serin Glycolipidd Cerebrolysides Lipoproteins VLDL, LDL, HDL Other lipids Sterols Cholesterol, phytosterols, Vitamin D, bile salts Lipid Vitamins A, E, K derivatives  Macronutrients – Lipids The role of lipids in the body: ✔ Energy: 1 g lipids = 9 Kcal ✔ Structure of nerve cells and cell membranes ✔ Maintaining the position of organs, protection against injury and shock ✔ Digestion, absorption and transport of fat-soluble vitamins ✔ Reduction of gastric secretions, gastric emptying ✔ Stimulation of bile and pancreatic secretion ✔ Synthesis of steroid hormones and sex hormones ✔ Synthesis of prostaglandins  Macronutrients – Lipids Recommendations: ✔ Lipids must cover 20-30% of the daily caloric intake ✔ Lipid intake must be balanced: 1/3 saturated fatty acids, 1/3 monounsaturated fatty acids, 1/3 polyunsaturated fatty acids ✔ Recommendation of guidelines: below 7% saturated fats, 10% polyunsaturated fats, 10-15% monounsaturated fats and avoiding trans fats (pies, cakes, pastries) ✔ Saturated and trans fats increase LDL cholesterol and cardiovascular risk ✔ Unsaturated fats - cardiovascular protective role: lower LDL, anti-inflammatory action, maintenance of cognitive functions and immune response ✔ Excessive lipid intake favors obesity, dyslipidemia, atherosclerosis, cardiovascular diseases  Healthy fatty acids Monounsaturated Polyunsaturated omega-6 Polyunsaturated omega-3 Avocado Oils (corn, soy) Fatty fish: herring, salmon, Oils (olive, peanut, sesame) Nuts tuna, mackerel Olive Mayonnaise NUTS Peanut butter Pumpkin seeds, sunflower Sesame seeds Unhealthy fatty acids Saturated Trans Ham Fried foods (partially hydrogenated) Butter Margarine (hydrogenated lipids) Chocolate Fast food Coconut Doughnuts Whipped cream CAKE Meat Chips Whole milk and whole milk Cookies products Popcorn Sour cream Oils (coconut, palm)  Digestion and absorption of lipids ✔ In the stomach: gastric lipase hydrolyzes short-chain triglycerides into fatty acids and glycerol ✔ In the small intestine: long-chain triglycerides are emulsified under the action of bile salts and broken down under the action of pancreatic lipase into free fatty acids and monoglycerides -> pass from the intestinal lumen -> border into the brush -> mucosal cells where they reassemble into new triglycerides ✔ Triglycerides + cholesterol + phospholipids -> chylomicrons -> liver -> repackaged in lipoproteins -> adipose tissue where they are metabolized under the action of lipoprotein lipase => glycerol, fatty acids and phosphates which are taken up and used by the cells  Digestion of macronutrients – summary Nutrient Produce Produce glucose Produce amino Produce fat energy acids and proteins deposits Carbohydrates Yes Yes Yes – when nitrogen is Yes availabe Lipids Yes Yes – when Yes – when nitrogen Yes carbohydrates are ia availabe not available Proteins Yes Yes – when Yes Yes carbohydrates are not available  Micronutrients – Vitamins Classification of vitamins: ♦ fat-soluble vitamins: vitamins A, D, E, K ♦ water-soluble vitamins: vitamin C (ascorbic acid), vitamins from group B (B1- thiamine, B2-riboflavin, B6- pyridoxine, B9- folic acid, B12- cobalamin) A Vitamin ✔ It is found in food in 2 forms: retinol and carotenoids Sources: ✔ animal products – retinol (liver, milk, cheeses, egg yolk, fish) and vegetable products – carotenoids (carrots, apricots, squash, melon) Roles in the body: ✔ Functioning of the visual analyzer ✔ Cell growth and differentiation ✔ Stimulation of the immune system ✔ The normal structure of the skin and mucous membranes  Micronutrients – Vitamins D Vitamin ✔ It is found in 2 forms: ergocalciferol (D2) - vegetable origin and cholecalciferol (D3) - animal origin ✔ Vitamin D3 can also be synthesized in the skin under the action of UV rays Sources: ✔ Brewer's yeast (D2), fatty fish, egg yolk, milk, cereals (D3), mushrooms (D2) Roles in the body: ✔ Maintenance of calcium and phosphorus homeostasis ✔ Growth and development of bone tissue ✔ Cell growth and differentiation ✔ Immunostimulation ✔ It inhibits the proliferation of tumor cells  Micronutrients – Vitamins C vitamin ✔ The least stable of vitamins Sources: ✔ Poppies, blueberries, peppers, kiwi, citrus fruits, spinach, cabbage, broccoli Roles in the body: ✔ Connective tissue and collagen synthesis ✔ Stimulation of the immune system ✔ Increase in the absorption of iron ✔ Deactivation of histamine and amelioration of nasal congestion ✔ Antioxidant, protects tissues from oxidative stress  Micronutrients – Vitamins B group vitamins Sources: ✔ B1 (thiamine): whole grains, legumes (peas – the richest source), nuts, meat (pork – the richest source), fish, potatoes ✔ B2 (riboflavin): milk and milk products (main source), meat, offal, fish, eggs, whole grains ✔ B6 (pyridoxine): meat, offal, fish, eggs, dairy, whole grains ✔ B12 (cyanocobalamin): exclusively in products of animal origin Main role in the body: ✔ Normal development and functioning of the nervous system  Digestion and absorption of micronutrients Vitamins and minerals ✔ Fat-soluble vitamins (A, D, E, K) - digestion and absorption proceed similarly to lipids in the presence of bile secretion and specific enzymes ✔ Water-soluble vitamins (group B, C) - absorbed at the intestinal level either by passive diffusion (B6, folic acid in large quantities) or by transport proteins (B1, B2, folic acid, B12, vitamin C) ✔ Minerals - variable and complex absorption, interactions at the level of the absorption process between different mineral elements  Factors that influence digestion and absoption ✔ Psychological factors ♦ appearance, smell, taste ♦ the emotional climate ✔ Bacterial action ♦ imbalance of normal flora - inflammation of the digestive mucosa - influences on digestion and absorption ♦ products made by microorganisms – interference with digestion and absorption of nutrients ✔ Effects of food preparation ♦ properly prepared meat - more accessible to digestive juices than raw meat ♦ frying food at excessive temperatures -> acrolein - inhibits digestive secretions ♦ thermal preparation of vegetables and vegetables - significant losses of water- soluble vitamins  The main food groups – Guide of the Romanian Nutrition Society The food pyramid ✔ graphical representation of nutritional standards ✔ the amount and types of food that must be consumed daily to maintain health expressed as a percentage of the caloric requirement or in daily portions of food that ensure the necessary intake of nutritional principles ✔ the balance, variety and moderation with which some food must be eaten Main food groups: ✔ bread, cereals, rice and pasta ✔ vegetables and vegetables ✔ fruits ✔ milk and derivatives ✔ meat, fish, eggs ✔ dietary fats and oils Serve size  The vegetarian diet pyramid - lowers LDL - increases HDL - lowers BP - reduces the risk of cancer, CVD, type 2 DM - increases life expectancy  Mediterranean diet pyramid - the incidence of CVD decreases - reduces the risk of gastric and colon cancer - Alzheimer's prevention - prevention and control of DM, dyslipidemias  The DASH diet pyramid - lowers BP - lowers the risk of CVD and HF - reduces the risk of cancer, kidney stones, DM  The main food groups Bread, cereals, rice, pasta ✔ essential components of the diet, variable nutritional value depending on the degree of refinement during processing ✔ the main nutritional principles: - digestible polysaccharides (starch) - non-digestible polysaccharides (food fibers) - mineral salts (iron, phosphorus) - vitamin E and group B (thiamine, nicotinic acid) - proteins - relatively low amount  The main food groups Vegetables ✔ the main source of vitamins and minerals, also contributing to the daily intake of carbohydrates and dietary fiber ✔ increased content in minerals and water ✔ the main nutritional principles: - vitamin C (broccoli, cauliflower, cabbage, tomatoes, spinach - group B vitamins (spinach, lettuce, cabbage, onion) - vitamin A (carrots, beetroot, pumpkin) - minerals (potassium, calcium, iron) - dietary fiber  The main food groups Fruits ✔ increased content in water, small molecule carbohydrates, cellulose, mineral salts ✔ proteins - poorly represented ✔ carbohydrates – simple (glucose, fructose, sucrose) and polysaccharides (starch, cellulose, gums, pectins) ✔ lipids – especially in seeds; unsaturated fatty acids: walnuts, hazelnuts, almonds, peanuts ✔ vitamins - especially water-soluble (vitamin C: citrus fruits, apples, kiwi, strawberries) ✔ minerals - iron (peaches, apricots, figs, grapes)  The main food groups Milk and milk products ✔ high nutritional value, but some nutrients are poorly represented (iron, vitamins C and D) ✔ the main nutritional principles: - proteins - casein and lactalbumin - carbohydrates - lactose - fats, in emulsified form - quickly absorbable minerals (calcium and phosphorus). - fat-soluble vitamins (A) - water-soluble vitamins from group B (riboflavin)  The main food groups Meat, fish ✔ The main nutritional principles: - proteins with high biological value – all essential amino acids, variable content depending on the species - fats – variable content depending on the species and anatomical segment - mineral salts: iron, phosphorus (liver, brain) - vitamins: especially from group B (thiamine Eggs - content rich in proteins with high biological value: ovalbumin, ovovitelline - phospholipids - water-soluble (B) and fat-soluble vitamins (A, D, E, K) - minerals: phosphorus, calcium, iron