Untitled Quiz

Nutrition and Health

• Nutrition plays a crucial role in promoting and maintaining health.
• Nutritional requirements vary across different life stages, including infancy, toddlerhood, adolescence and adulthood.
• Adults' nutritional needs are influenced by factors like activity levels, weight status, and the presence of any health conditions.
• Elderly individuals are prone to malnutrition and require tailored diets due to age-related diseases.
• Modern lifestyle changes, including industrialization, urbanization and mechanization, have resulted in shifts in eating habits and increased sedentary lifestyles.

Unhealthy Diets and Chronic Diseases

• An unhealthy diet is linked to the rising prevalence of chronic diseases such as diabetes, obesity, cardiovascular disease, cancer and osteoporosis.
• Primary prevention strategies focus on controlling modifiable risk factors, including:
  • Eating habits
  • Sedentary lifestyle
  • Smoking
  • Alcohol consumption
  • Healthy lifestyle

Eating vs. Nutrition

• Eating refers to the act of consuming food for sustenance.
• Nutrition is the science that focuses on understanding the body's needs for energy and essential nutrients for optimal growth, development, and maintenance.
• Nutritional requirements are influenced by various factors, including:
  • Age
  • Sex
  • Physical activity levels
  • Environmental conditions
  • Presence of health or disease conditions

Nutrition

• The process through which the body obtains substances from the external environment to support vital functions and growth.
• These substances are called nutritional principles or nutrients and are modified by the body to ensure the development and normal functioning of cells, tissues, organs, and systems.
• The body requires a continuous supply of nutrients to carry out its activities, even when food intake is discontinuous.

Classification of Nutrients

• Macronutrients: Needed by the body in large quantities:
  • Carbohydrates
  • Proteins
  • Fats (lipids)
• Micronutrients: Needed in small amounts and most cannot be synthesized by the body.
  • Fat-soluble vitamins: A, D, E, K
  • Water-soluble vitamins: C (ascorbic acid), B group (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 and an indispensable nutrient.

Physiological Basis of Nutrition

• Digestion: The biochemical process of breaking down food in the gastrointestinal tract (GIT) into simple substances for absorption.
• Absorption: The transport of nutrients through the cells of the GIT into the blood.
• Digestion stages:
  • Ingestion: Introduction of food into the GIT.
  • Propulsion: Movement of food through GIT (swallowing + peristalsis).
  • Mechanical digestion: Mastication, kneading in the stomach, segmentation in the small intestine.
  • Chemical digestion: Chemical decomposition of food under the action of digestive enzymes.
  • Absorption: Transport of end products of digestion into the blood.
  • Defecation: Elimination of undigested and unabsorbed substances as faeces.

Macronutrients - Carbohydrates

• Organic substances made up of carbon, oxygen, and hydrogen atoms.
• Provide energy for cellular processes (1 g of carbohydrates = 4 Kcal).
• Classification:
  • Simple carbohydrates (fast absorption):
    • Monosaccharides: Glucose, fructose, galactose.
    • Disaccharides: Sucrose, lactose, maltose.
  • Complex carbohydrates (polysaccharides - slow absorption):
    • Digestible polysaccharides: Starch, glycogen.
    • Non-digestible polysaccharides (dietary fiber): Cellulose, hemicelluloses, lignins.

Dietary Fiber

• Soluble fiber: Binds carcinogens, lowers plasma cholesterol, delays gastric emptying, delays digestion and absorption of carbohydrates.
• Insoluble fibers: Increase the volume of faeces, decrease transit time, decrease the production of free radicals in the digestive tract.

The Role of Carbohydrates in the Body

• Main source of energy for cells (1 g carbohydrates = 4 Kcal).
• Protect proteins when intake is insufficient.
• Synthesis of nucleotides and nucleic acids.
• Normal bowel function.

Recommendations for Carbohydrate Intake

• Carbohydrates should cover 50-65% of daily caloric intake.
• Limit consumption of foods containing simple carbohydrates.
• Consumption of complex carbohydrates (vegetables and fruits) is recommended.

Digestion and Absorption of Carbohydrates

• Oral cavity: Salivary amylase hydrolyzes starch to dextrins and maltose.
• Stomach: Amylase activity is stopped by hydrochloric acid.
• Small intestine:
  • Duodenum: Pancreatic amylase breaks down starch into dextrins and maltose.
  • Brush border: Sucrase, lactase, maltase, and isomaltase break down disaccharides into monosaccharides (glucose, galactose, fructose).
• Monosaccharides are absorbed into the capillaries of the intestinal villi, transported to the portal vein to the liver, and then distributed throughout the body.
• Glucose is transported to tissues and stored as glycogen in the liver and muscles.
• Fructose and galactose are converted to glucose in the liver.
• Non-digestible carbohydrates (dietary fiber) are eliminated unmodified.

Macronutrients - Proteins

• Complex molecules made up of chains of essential and non-essential amino acids.
• Essential components of the body with structural, functional, and energetic roles.
• Classification:
  • Biological value/protein quality:
    • Complete proteins: Contain all essential amino acids in appropriate proportions (meat, fish, eggs, milk, soy).
    • Partially complete proteins: 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).
  • Source:
    • Animal proteins: Meat, eggs, milk.
    • Vegetable proteins: Soy, peas, beans, almonds, hazelnuts, nuts, mushrooms.

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 water balance.
  • Maintaining normal pH.
  • Transport: Hemoglobin (respiratory gases), plasma lipoproteins (lipids).
  • Immune role: Antibodies.
  • Hemostasis and coagulation.
• Energy: 1 g protein = 4 Kcal.

Recommendations for Protein Intake

• Proteins must cover 12-15% (max 20%) of the daily caloric intake.
• 0.8 - 1.2 g/kg body weight.
• Ratio of animal protein to vegetable protein = 1:1.

Digestion and Absorption of Proteins

• Stomach: Proteins are broken down by pepsin into peptones and large polypeptides.
• Duodenum: Contact of chyme with duodenal mucosa activates enterokinases, which transforms trypsinogen into trypsin, activating chymotrypsin and carboxypeptidase.
• Trypsin, chymotrypsin, carboxypeptidase: Continue hydrolysis to form small polypeptides (dipeptides, tripeptides) and amino acids.
• Brush border: Dipeptides and tripeptides are hydrolyzed to amino acids.
• Amino acids are absorbed through four different active transport systems via co-transport with Na into the liver and released into the general circulation.

Macronutrients - Lipids

• Complex molecules made up of a polyalcohol and fatty acids.
• Found in three forms: triglycerides (95% of ingested lipids), phospholipids, and sterols (cholesterol and phytosterols).
• Classification:
  • 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 derivatives (Vitamins A, E, K).

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, protecting 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.

Recommendations for Lipid Intake

• Lipids should comprise 20-30% of the daily caloric intake.
• Maintain a balanced lipid intake: 1/3 saturated fatty acids, 1/3 monounsaturated fatty acids, 1/3 polyunsaturated fatty acids.
• Guidelines: Below 7% saturated fats, 10% polyunsaturated fats, 10-15% monounsaturated fats, and avoid trans fats.
• Saturated and trans fats: Increase LDL cholesterol and cardiovascular risk.
• Unsaturated fats: Lower LDL, anti-inflammatory action, maintain cognitive functions and immune response.
• Excessive lipid intake increases risk of obesity, dyslipidemia, atherosclerosis, and cardiovascular diseases.

Healthy and Unhealthy Fatty Acids

• Healthy:
  • Monounsaturated: Avocado, olive oil, peanut oil, sesame oil, olive, peanut butter, sesame seeds.
  • Polyunsaturated omega-6: Corn oil, soy oil, nuts, mayonnaise, pumpkin seeds, sunflower seeds.
  • Polyunsaturated omega-3: Fatty fish (herring, salmon, tuna, mackerel), nuts.
• Unhealthy:
  • Saturated: Ham, butter, chocolate, coconut, whipped cream, meat, whole milk and whole milk products, sour cream, coconut oil, palm oil.
  • Trans: Fried foods, margarine, fast food, doughnuts, cake, chips, cookies, popcorn.

Digestion and Absorption of Lipids

• Stomach: Gastric lipase hydrolyzes short-chain triglycerides into fatty acids and glycerol.
• Small intestine: Long-chain triglycerides are emulsified by bile salts and broken down by pancreatic lipase into free fatty acids and monoglycerides, passing into mucosal cells where they reassemble into new triglycerides.
• Triglycerides + cholesterol + phospholipids: Form chylomicrons, which are transported to the liver where they are repackaged into lipoproteins and then stored in adipose tissue where they are metabolized by lipoprotein lipase into glycerol, fatty acids, and phosphates, which are taken up and used by cells.

Digestion of Macronutrients - Summary

Micronutrients - Vitamins

• Classification:
  • Fat-soluble vitamins: A, D, E, K.
  • Water-soluble vitamins: C (ascorbic acid), B group.
• Vitamin A: Found in food in two forms: retinol and carotenoids.
  • Sources: Animal products (liver, milk, cheeses, egg yolk, fish) and vegetable products (carrots, apricots, squash, melon).
  • Roles in the body: Functioning of the visual analyzer, cell growth and differentiation, stimulation of the immune system, maintenance of the normal structure of skin and mucous membranes.
• Vitamin D: Found in two forms: ergocalciferol (D2) - vegetable origin, and cholecalciferol (D3) - animal origin. Vitamin D3 can also be synthesized in the skin under 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, inhibition of the proliferation of tumor cells.
• Vitamin C: 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, increased absorption of iron, deactivation of histamine and amelioration of nasal congestion, antioxidant, protects tissues from oxidative stress.
• B Group Vitamins:
  • Sources:
    • B1 (thiamine): Whole grains, legumes (peas), nuts, meat (pork), fish, potatoes.
    • B2 (riboflavin): Milk and milk products, 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 (B group, C): Absorbed at the intestinal level either by passive diffusion (B6, folic acid in large quantities) or by specific transport proteins (B1, B2, folic acid, B12, vitamin C).
  • Minerals: Variable and complex absorption, with interactions between different mineral elements at the absorption level.

Factors Influencing Digestion and Absorption

• Psychological factors: Appearance, smell, taste, the emotional climate.
• Bacterial action: Imbalance of normal flora can cause inflammation of the digestive mucosa, influencing digestion and absorption. Products made by microorganisms can interfere with digestion and absorption of nutrients.
• Effects of food preparation: Properly prepared meat is more accessible to digestive juices than raw meat. Frying food at excessive temperatures produces acrolein, which inhibits digestive secretions. Thermal preparation of vegetables can lead to significant losses of water-soluble vitamins.

The Main Food Groups - Guide of the Romanian Nutrition Society

• The food pyramid: A graphical representation of nutritional standards, showing the amount and types of food that should be consumed daily to maintain health. This is expressed as a percentage of the caloric requirement or in daily portions of food that ensure the necessary intake of nutritional principles.
• The pyramid emphasizes balance, variety, and moderation.

Main Food Groups

• Bread, cereals, rice, and pasta: Essential components of the diet with variable nutritional value depending on the degree of refinement during processing.
  • Main nutritional principles: Digestible polysaccharides (starch), non-digestible polysaccharides (dietary fiber), mineral salts (iron, phosphorus), vitamin E and B group (thiamine, nicotinic acid), and proteins (relatively low amount).
• Vegetables: Main source of vitamins and minerals, also contributing to the daily intake of carbohydrates and dietary fiber.
  • Main nutritional principles: Vitamin C, B group vitamins, vitamin A, minerals, and dietary fiber.
• Fruits: Increased content in water, small molecule carbohydrates, cellulose, and mineral salts. Proteins are poorly represented.
  • Main nutritional principles: Carbohydrates (simple and polysaccharides), lipids, vitamins (especially water-soluble), and minerals.
• Milk and milk products: High nutritional value but some nutrients are poorly represented (iron, vitamins C and D).
  • Main nutritional principles: Proteins (casein and lactalbumin), carbohydrates (lactose), fats in emulsified form, and quickly absorbable minerals (calcium and phosphorus).
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