Introduction to Nutrition

Nutrition: Definition and Function

• Nutrition is the study of food and how the body uses it to maintain life, promoting growth and overall health.
• Nutrients are chemical substances found in food that provide nourishment to the body.

Macronutrients: Carbohydrates

• Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen.
• They provide the body's major source of energy (80-100% of calories).
• Classification of carbohydrates:
  • Monosaccharides (simple sugars): glucose, fructose, galactose
  • Disaccharides (made up of two monosaccharides): sucrose, lactose, maltose
  • Polysaccharides (made up of links of monosaccharides): starch, cellulose, dextrins, pectins, glycogens
• Functions of carbohydrates:
  • Serve as major source of energy for the body
  • Exert protein-sparing action
  • Necessary for metabolism of fats
  • Aid in normal elimination of digested mass (fibers)
  • Supplies significant quantities of proteins, mineral, and B vitamins
  • Encourages growth of beneficial bacteria in the gut (lactose)

Health Effects of Starch and Fibers

• Weight control: fibers rich in complex carbohydrates tend to be low in fat and added sugars, promoting weight loss
• Protection against heart diseases and stroke: high carbohydrate diets rich in whole grains
• Prevention of certain cancers: high carbohydrates
• Weight control: high carbohydrates, low-fat diets
• Health of the large intestine: dietary fibers

Macronutrients: Proteins

• Proteins are organic compounds containing carbon, hydrogen, oxygen, and nitrogen.
• Building blocks of proteins are amino acids.
• Classification of proteins:
  • Simple proteins: albumins, globulins, gliatins, prolamins, albuminoids, histones, and protamines
  • Compound proteins: nucleoproteins, mucoproteins, glycoproteins, lipoproteins, phosphoproteins, chromoproteins, and metalloproteins
  • Derived proteins: product formed in various stages of hydrolysis of protein molecule
• Function of proteins:
  • Repair worn-out body tissues
  • Build new tissues by supplying necessary amino acids
  • Source of energy and heat
  • Contribute to essential body secretions and fluids, enzymes, and hormones
  • Help in variety of metabolic processes

Protein Deficiency

• Characteristics: marasmus, kwashiorkor
• Food deprivation: severe, semi-starvation
• Onset: 6 months to 4 years, 1-6 years
• Deficiency: protein and calories, protein only
• Appearance: old man's face, moon face

Macronutrients: Fats

• Fats are considered as organic nutrients containing carbon, hydrogen, and oxygen attached to a glycerol base.
• Classification of fats:
  • Simple lipids: triglycerides
  • Compound lipids: phospholipids, glycolipids, lipoproteins
  • Derived lipids: fatty acids, glycerol, steroids
• Function of fats:
  • Important source of calories
  • Maintenance of constant body temperature
  • Fat cushions vital organs against physical trauma
  • Facilitates absorption of fat-soluble vitamins
  • Provides satiety and delays the onset of hunger
  • Contributes to flavor and palatability of diet

Micronutrients: Vitamins

• Vitamins are a group of unrelated organic compounds essential for metabolic reactions within cells.
• Classification of vitamins:
  • Fat-soluble vitamins: A, D, E, K
  • Water-soluble vitamins: B, C
• Functions of vitamins:
  • Vitamin A: maintains normal vision, keeps lining of mouth, nose, throat, and respiratory tract healthy
  • Vitamin D: helps build and maintain strong bones and sound teeth
  • Vitamin E: maintains nerves, muscles, and a healthy reproductive system
  • Vitamin K: helps in normal clotting of the blood
  • Vitamin C: increases the body's resistance to infection
  • Vitamin B1 (Thiamine): prevents beri-beri, keeps nerves in healthy condition
  • Vitamin B2 (Riboflavin): keeps eyes and skin healthy
  • Vitamin B3 (Niacin): promotes normal digestion and keeps nerves in healthy condition
  • Vitamin B5 (Pantothenic acid): essential for carbohydrate, protein, and fat metabolism
  • Vitamin B6 (Pyridoxine): helps the body use carbohydrate, fat, and protein
  • Vitamin B9 (Folic acid): aids in metabolism of genetic material
  • Vitamin B12 (Cobalamin): maturation of red blood cells, protects the "myelin" the fatty material

Micronutrients: Minerals

• Minerals are elements in their simple inorganic forms.
• Classification of minerals:
  • Macronutrient minerals: Calcium, Sodium, Phosphorus, Potassium, Sulfur, Chloride, Magnesium
  • Micronutrient minerals: Iron, Iodine, Zinc, Selenium, Manganese, Copper, Molybdenum, Cobalt, Chromium
• Functions of minerals:
  • Calcium: build and maintain strong bones and teeth, promotes normal blood clotting
  • Magnesium: helps regulate body processes, aids in normal functioning of body enzymes
  • Sodium: maintains proper water balance within the body, preserves normal movement of muscles and nerve impulse transmission### Potassium (K)
• Chief cation in Intracellular Fluid (ICF) with a normal blood serum value of 3.5-5.5 mEq/liter
• Helps in muscle contraction, nerve impulses, and proper functioning of the heart and kidneys
• Regulates blood pressure and water balance in cells, important in CHO and CHON metabolism
• Deficiency: hypokalemia, causing muscular weakness, increased nervous irritability, mental disorientation, and cardiac irregularities
• Excess: hyperkalemia, leading to heart block
• Sources: bananas, meat, milk, legumes, potatoes, and some dried fruits

Phosphorous (P)

• Important in pH regulation and principal anion in the Intracellular Fluid (ICF)
• Helps in proper bone and tooth development
• Facilitates quick release of energy for muscle contraction, transports lipids and fatty acids in the blood
• Transports nutrients in and out of cells
• Prevents rickets and demineralization of bones
• Deficiency: weakness of muscles, stunted growth, and defective structure of teeth and bones
• Excess: impairment of the body's use of iron and calcium
• Sources: milk products, meat, organ meat, poultry, seafood, legumes, cheese, dried beans, sunflower and pumpkin seeds, nuts, and whole grains

Sulfur (S)

• Occurs in almost every protein cell
• Functions: making protein, regulating gene expression, building and repairing DNA, and helping the body metabolize food
• Sources: protein-rich foods

Chloride (Cl)

• Major anion in the Extracellular Fluid (ECF) and forms gastric juice
• Helps maintain osmotic pressure and acid-base equilibrium in the body
• Helps balance the pH level of the blood
• Maintains the strong acidity of the stomach as part of hydrochloric acid
• Deficiency: alkalosis
• Excess: acidosis
• Sources: pickles, canned soup, processed foods, condiments, and canned foods

Iron (Fe)

• Component of hemoglobin
• Functions: helps build and maintain blood supply, prevents simple anemia, and gives healthy red color to the blood
• Deficiency: iron deficiency anemia, easy fatigability, general weakness, poor physical performance, paleness in the face, conjunctiva, lips, and fingernails, weight loss, and koilonychias
• Excess: hemochromatosis and hemosiderosis
• Sources: liver, red meat, organ meat, egg yolk, green and red mongo, soybeans

Copper (Cu)

• Trace mineral necessary for survival
• Functions: plays a role in making red blood cells and maintaining nerve cells and the immune system, helps the body form collagen and absorb iron, and plays a role in energy production
• Deficiency: anemia, anorexia, hypotonia, edema, and retarded growth (CNS abnormalities)
• Excess: Wilson's disease, which is a genetic disorder in which excess copper builds up in the body
• Sources: organ meat, egg yolk, oysters, nuts, cereals, whole grains

Iodine (I)

• Mineral component of the hormone thyroxine
• Functions: helps in normal functioning of the thyroid gland in regulating energy metabolism, protein synthesis, tissue growth, and reproduction, and prevents goiter
• Deficiency: enlarged thyroid gland (goiter), painful swallowing, cretinism, myxedema, and increased risk of abortion, stillbirths, miscarriage, and infant deaths
• Excess: thyrotoxicosis, induced acne-like skin lesions, and worsening of pre-existing acne
• Sources: seafood, seaweeds, and iodized salt

Manganese (Mn)

• Mineral constituent of vitamin B1
• Functions: essential constituent for bone structure, reproduction, and normal functioning of the nervous system, and takes part in enzymatic actions in the body
• Deficiency: problem with skeletal abnormality
• Sources: nuts, cereals, legumes, dried fruits, green leafy and non-leafy vegetables

Cobalt (Co)

• Mineral constituent of B12
• Functions: forms of cobalamin or vitamin B12 that helps treat a certain type of anemia, necessary for formation of RBC, and essential for normal functioning of all cells
• Deficiency: pernicious anemia, poor growth, poor appetite, restlessness, and progressive emaciation
• Excess: polycythemia
• Sources: liver, oysters, clams, poultry, saltwater fish

Zinc (Zn)

• Antioxidant mineral
• Functions: helps the body use protein and carbohydrates, vital for growth and development, synthesis of cell protein (formation of DNA & RNA), and helps hasten wound healing
• Deficiency: growth failure, impaired wound healing, impaired sense of taste and smell, and sexual infantilism in teenagers
• Excess: nausea and vomiting, abdominal cramps, diarrhea, and gastrointestinal irritation
• Sources: meat, milk, legumes, nuts, poultry, fish, whole grain cereals, and breads

Fluorine (Fl)

• Favors deposition of calcium
• Functions: prevent tooth decay and strengthening the bones
• Deficiency: dental caries
• Excess: dental fluorosis, osteosclerosis, growth depression, and fatal poisoning
• Sources: toothpaste and fluoridated water

Selenium (Se)

• Antioxidant mineral
• Functions: integral component of certain enzymes, helps prevent certain types of protein-energy malnutrition, regulates proper immune response, and aids in proper functioning of the heart muscle
• Deficiency: keshan's disease, cancer, and less able immune system to fight off diseases
• Excess: liver damage
• Sources: organ meats, cereals, dairy products

Chromium (Cr)

• Part in glucose metabolism
• Functions: helps the body use carbohydrates and fats, and stimulates synthesis of fatty acids and cholesterol in the liver
• Deficiency: impaired action of insulin, and low blood glucose level
• Sources: corn oil, clams, cereals, vegetables, and meats

Water

• 60-70% of total body weight
• Deprivation of 10% water = illness
• 20% dehydration = death
• Functions: acts as a solvent for all products of digestion, carries nutrients to the tissues, removes waste products from the tissues, helps regulate body temperature, helps balance the acid-base balance, and sends messages between cells

Nutrition Tools, Standards, and Guidelines

• Dietary Reference Intakes (DRIs): a generic term for a set of nutrient reference values
• Patient's Dietary Reference Intake: collective term comprising reference values for energy and nutrients levels of intake
• Estimated Average Requirement (EAR): a daily nutrient intake level that meets the median or average requirement of a healthy individual in a particular life stage and sex group
• Recommended Dietary Allowance (RDA): derived from EAR, an estimate of the intake at which the risk of inadequacy to an individual is 50%
• Recommended Energy/Nutrient Intake: a level of intake of energy or nutrient which is considered adequate for the maintenance of health and well-being of healthy persons in the population
• Adequate Intake (AI): daily nutrient intake level that is based on observed or experimentally-determined approximation of the average nutrient intake by a group of apparently healthy people
• Tolerable Upper Intake Level (UL): the highest average daily nutrient intake level likely to pose no adverse health effect to almost all individuals in the general population

Learn about the basics of nutrition, including the study of food and how the body uses it, and the different types of macronutrients.