Nutrition and Nutrients - Comprehensive Macro/Micro Nutrients and Contamination Notes

1.1 Protein

  • Functions of protein
    • Building proteins from amino acids forms the base of all body cells; essential for building, maintaining and repairing body tissues. Structural elements (bones, cartilage, muscle, tendons, skin, hair) are mainly made of protein.
    • Enzymes are proteins that speed up chemical reactions.
    • Hormones are chemical messengers and metabolic regulators made of protein.
    • Antibodies (immunity) are proteins; proteins carry important substances in the blood (e.g., oxygen) and help regulate blood sugar and blood clotting.
    • Routine body processes not used for growth/repair can be used to provide energy.
  • Energy yield
    • 1 g of protein yields 16.8 kJ1\ \text{g of protein yields } 16.8\ \text{kJ}
  • Sources and amino acids
    • The basic building blocks are amino acids; the body needs 22 amino acids to build body cells.
    • The body manufactures most amino acids, but 8 must be supplied by the diet (essential amino acids).
    • The biological value (BV) of a protein refers to the number of essential amino acids it contains; higher BV means better quality.
    • High-BV proteins are found mainly in animal products (milk, eggs, cheese, meat, fish). Soy proteins also have high BV.
    • Proteins with low BV are found in breads, cereals, legumes, and vegetables; they lack some essential amino acids but can supplement each other (e.g., cereals + milk, bread + meat) to provide a good quality protein.
  • Protein quality and affordability
    • Quality protein can be obtained more affordably by combining plant and animal sources.
  • Protein requirements and health implications
    • Excess protein: may increase urinary calcium excretion and risk kidney stones; could play a role in heart disease (animal proteins contain saturated fat and cholesterol).
    • In developing countries, protein deficiency leads to protein-energy malnutrition (e.g., marasmus in young children; kwashiorkor and other forms in older children/adults).
  • Practical notes
    • The body cannot manufacture 8 essential amino acids; include diverse protein sources to meet needs.

1.2 Carbohydrates

  • Functions of carbohydrates
    • Primary energy source; starch and sugars are major energy sources.
    • Carbohydrates have a protein-sparing action: with adequate carbohydrate, the body uses less protein for energy.
    • Carbohydrates are needed for normal oxidation of fats.
    • Excess carbohydrates are stored in the liver as glycogen, which can be converted back to glucose as needed.
  • Sources and classifications
    • Carbohydrates are divided into sugars, starch, and cellulose (dietary fiber).
    • Glucose (blood sugar) is the primary sugar used for energy; natural sugars occur in foods (honey, fruits, some vegetables) and in the blood as glucose.
    • Fructose (fruit sugar) is found in fruits, plant juices, honey; the sweetest simple sugar; generally safe for people with diabetes.
    • Sucrose (table sugar) from cane/beet; added to many foods.
    • Lactose is the main sugar in milk.
    • Starch is the major form of stored carbohydrate in plants (e.g., tomatoes, corn, wheat, soybeans).
  • Fiber (dietary fiber)
    • Soluble fiber forms a gel in water; can reduce blood cholesterol and lower heart disease risk (e.g., oats, oat bran, barley, beans, lentils, citrus fruits, apples, some vegetables).
    • Insoluble fiber is not digestible; binds water and adds bulk to stool; found in bran, whole wheat bread, cereals, legumes, brown rice.
    • Functions: supports digestive health, absorbs toxins from intestines, promotes regular bowel movements, provides a sense of fullness and bulk, helps control blood glucose.
  • Daily carbohydrate intake and energy balance
    • Daily carbohydrate intake: 25−30 g/day25-30\ \text{g/day} (as stated in the transcript).
    • Carbohydrates are essential for health; excessive intake converts to fat and can be stored around hips/thighs.
    • Too few carbohydrates can cause metabolic imbalances; fat may be used for energy, and protein could be broken down for energy, risking muscle loss.
    • Other potential issues with very low carbohydrate intake: fatigue, nausea, loss of appetite, and a drop in blood pressure when standing (orthostatic hypotension).

1.3 Fats (Lipids)

  • Functions of fat
    • Concentrated energy source; 1 g fat yields 37.8 kJ1\ \text{g fat yields } 37.8\ \text{kJ}.
    • Provides essential fatty acids required for health.
    • Aids digestion and helps regulate body temperature; facilitates absorption of fat-soluble vitamins (A, D, E, K).
    • Fat slows gastric emptying, delaying hunger.
  • Types and dietary implications
    • Saturated fats: usually solid at room temperature; limit to about one-third of total fat intake.
    • Sources: animal fats (meat, butter, cream, bacon, eggs) and some fish oils; certain plant fats (coconut oil, palm kernel oil, cocoa butter) are high in saturated fats; present in foods like nuts, milk/dairy, chocolate, cakes, chips.
    • Polyunsaturated fats: include essential fatty acids (omega-3 and omega-6).
    • Sources: vegetable oils (sunflower, etc.) and oily fish (salmon, sardines, mackerel).
    • Omega-6: common in many foods; unlikely to be deficient.
    • Omega-3: found in the flesh of oily fish; at least two portions per week recommended.
    • Trans fatty acids: produced by hydrogenation (hydrogen gas added to fats) or when fats are repeatedly heated; harmful to cardiovascular health.
    • Common in hard margarine and foods made with hydrogenated fats (biscuits, pies, cakes, chips); intake should be minimized. Also found in deep-fried foods when oil is reheated.
  • Cholesterol
    • A fat-like substance found in all animal foods (meat, poultry, fish, milk and dairy, egg yolks); plants do not contain cholesterol.
    • Dietary cholesterol, along with saturated fat and trans fats, can raise blood cholesterol and increase heart disease risk.
    • To keep cholesterol at acceptable levels, maintain total fat within recommended amounts; prefer low-fat dairy products where possible.
  • Water and guidelines related to fats
    • Water is not a source of energy but is essential for survival; the “fat pyramid” concept is used to balance fats within overall dietary guidelines.

1.4 Water

  • Importance and functions
    • Essential nutrient; about 70% of body weight; contained in cells, body tissues, and blood.
    • Transport nutrients, remove wastes, protect CNS, lubricate joints, regulate body temperature (cooling via sweating).
  • Water intake and losses
    • Daily intake ~2 to 2.5 liters; losses occur via urine, feces, perspiration.
    • Balance between intake and excretion is normally maintained; higher losses (e.g., during exercise, vomiting, diarrhea) increase thirst and intake.
  • Effects of imbalances
    • Excess water can cause edema (swelling).
    • Dehydration from excessive losses or insufficient intake leads to dizziness, weakness, and can progress to severe outcomes.

1.5 Minerals

  • General role
    • Minerals comprise about 4% of body weight; 22 essential elements.
    • Minerals are components of enzymes, hormones, tissues and fluids; involved in metabolism, bone/teeth structure, glycogen/fat/protein synthesis, and more.
  • Macrominerals vs trace elements
    • Macrominerals (need >100 mg/day): calcium, phosphorus, magnesium, sodium, potassium.
    • Trace elements (<20 mg/day): iodine, iron, fluoride, zinc, manganese.
  • Food fortification
    • Fortification adds specific micronutrients to foods to improve intake (e.g., iron in refined flour, iodine in salt, vitamin D in milk).
  • Macro minerals: functions, sources, deficiency notes
    • Calcium: bone/teeth formation; normal blood clotting; normal nerve/muscle function; activates certain enzymes.
    • Main sources: milk, cheese, white bread, hard water; some beer, canned fish, greens; dairy products are high in calcium and phosphorus.
    • Deficiency: in children can cause poorly formed bones/teeth; in adults may cause osteomalacia; excessive calcium can deposit in organs.
    • Phosphorus: works with calcium for bone mineralization; active role in metabolism of carbs, fats, and proteins; energy release regulation and acid-base balance.
    • Sources: milk, cheese, nuts, meat, poultry, fish, eggs, whole grains.
    • Magnesium: essential for enzyme activity and protein synthesis; important for muscle and nerve function.
    • Sources: sauces, green leafy vegetables, cocoa, nuts, whole grains.
    • Sodium: maintains cell membrane permeability and acid-base balance; activates enzymes; helps nerve transmission; prevents muscle cramps.
    • Sources: table salt and processed foods.
    • Potassium: important for transmission of nerve impulses; helps prevent calcium loss in urine; supports muscle activity and can help lower blood pressure.
    • Sources: fruits (bananas, oranges) and vegetables.
  • Microminerals: iodine, iron, fluoride, zinc, manganese
    • Iodine: thyroid hormone (thyroxine) production; regulates metabolic rate; sources include fish, shellfish, vegetables; iodized salt.
    • Iron: essential for hemoglobin and oxygen transport; energy release via enzymes; sources include liver, kidneys, heart, eggs, leafy greens, fortified cereals.
    • Deficiency: iron-deficiency anemia; fatigue, weakness; reduced infection resistance.
    • Fluoride: hardens tooth enamel; reduces tooth decay; sources include fish, tea; may be added to drinking water.
    • Zinc: component of digestive enzymes; essential for growth, reproduction, blood clotting.
    • Manganese: involved in connective tissue formation and metabolism of carbohydrates and lipids; sources include nuts, whole grains, legumes, greens.
  • Deficiency/excess notes
    • Deficiencies can lead to specific diseases (e.g., iodine deficiency goiter; iron deficiency anemia; calcium/phosphorus deficiencies affect bones).
    • Excesses can cause toxicity (e.g., excessive calcium deposition, mineral imbalances).

1.6 Vitamins

  • Overview
    • Vitamins are small organic compounds needed for growth, maintenance, and reproduction; they work with enzymes, aid tissue formation, waste removal, and energy production.
    • Vitamins and minerals work together (e.g., vitamin C enhances iron absorption; vitamin D aids calcium absorption).
  • Fat-soluble vitamins (stored in body fat) and water-soluble vitamins (need daily intake as excess is excreted in urine)
  • Specific vitamins
    • Vitamin A (retinal/retinol)
    • Functions: vision (protect retina, improve low-light vision), maintenance of mucous membranes, growth, reproduction.
    • Main sources: liver, oily fish, cod liver oil, eggs, milk/dairy, butter, margarine, apricots, carrots, tomatoes, green leafy vegetables.
    • Deficiency: night blindness; rough, cracked skin; increased infection risk; possible eye/skin problems.
    • Vitamin D
    • Functions: works with calcium/phosphorus for bones/teeth; promotes calcium absorption; accelerates bone healing; UV light converts skin fat to vitamin D.
    • Sources: animal fats, cod liver oil, eggs, liver, fortified foods; sun exposure.
    • Deficiency: rickets; bone softening (osteomalacia) in adults; calcium/phosphorus imbalance.
    • Vitamin E
    • Function: antioxidant, protects cell membranes; supports reproduction; found in wheat germ, plant oils, margarine, butter, eggs, liver, greens.
    • Deficiency: rare; may cause hemolysis in infants; generally non-toxic.
    • Vitamin K
    • Function: essential for blood clotting; widely distributed in foods; synthesized by gut bacteria.
    • Deficiency: bleeding disorders in infants; rare in adults.
    • B Group Vitamins (water-soluble)
    • B1 (Thiamin): essential for energy release from carbohydrates; nervous system function; sources include brown rice, wheat germ, kidneys, legumes, whole grains, fortified breads.
      • Deficiency: beri-beri, edema, nerve/muscle problems.
    • B2 (Riboflavin): involved in metabolism of proteins, fats, carbohydrates; supports skin/nervous system; sources include liver, kidneys, milk, eggs, greens, meat, cereals.
      • Deficiency: cracked lips, skin disorders, light sensitivity, sore tongue.
    • Niacin (B3)
      • Involves metabolism of proteins, fats, carbohydrates; supports digestive and nervous systems; sources include meat, poultry, fish, liver, kidneys, whole grains, peanuts, legumes, eggs.
      • Deficiency: pellagra-like symptoms; dermatitis, diarrhea, dementia (and related issues).
    • Folic acid (B9)
      • Essential for cell growth, DNA formation; crucial in pregnancy for fetal development; sources: liver, kidneys, green leafy vegetables, enriched cereals.
      • Deficiency: anemia in pregnancy; neural tube defects risk.
    • Vitamin B12 (Cobalamin)
      • Essential for red blood cell formation and nervous system function; sources include liver, kidneys, meat, eggs, dairy; some cereals have B12 fortification.
      • Deficiency: pernicious anemia, fatigue, neurological issues.
    • Vitamin C (Ascorbic Acid)
    • Function: collagen synthesis, blood vessel integrity, wound healing, immune support; enhances iron absorption.
    • Sources: peppers, broccoli, Brussels sprouts, cabbage, guava, citrus fruits, strawberries, tomatoes, other fruits.
    • Deficiency: scurvy (gum and skin symptoms; anemia; weakness).

Chapter 8: Nutritional needs of different consumer groups

  • Chapter overview
    • Nutritional needs vary by person and change with life stages, illness, pregnancy, lactation, etc.
  • Pregnant women (general guidelines)
    • Weight gain: 10–13 kg during pregnancy is typical; excessive weight gain is discouraged.
    • Diet: avoid junk food; drink plenty of fluids; avoid alcohol due to fetal alcohol syndrome risk.
    • Energy needs: no extra energy in first trimester; extra kilojoules needed in second/third trimesters for fetal growth.
    • Protein: ensure adequate high-quality protein (meat, fish, poultry or soy).
    • Iron: supplementation often advised to build iron stores; breast milk does not provide iron for the baby after birth.
    • Calcium needs similar to non-pregnant women; ensure vitamin D for calcium absorption.
    • Folic acid (B9): essential before and early in pregnancy for rapid fetal development; deficiency linked to miscarriage and neural tube defects.
    • Vitamin C: supports connective tissue and iron absorption; fiber-rich foods recommended to prevent constipation.
  • Lactating mothers
    • Breastfeeding increases energy and protein needs; maintain adequate nutrition to support milk production.
    • Calcium and vitamin D requirements remain important; ensure vitamins/minerals to support both mother and baby.
    • Regular meals with vegetables, fruit, and whole grains, plus fluids to prevent dehydration and constipation; breastfeeding increases kilojoule use.
  • Babies: birth to one year
    • Energy and nutrients are critical; breast milk or iron-fortified formula provides essential nutrients early on.
    • Goat’s milk is close to human milk but not ideal as a sole source for infants; cow’s milk is discouraged before age 1 due to excessive protein and inadequate essential fats for nervous system development.
    • Introduce solid foods gradually after 6 months; complementary proteins and iron sources included; avoid excessive protein for immature kidneys.
    • Milk intake guidelines by weight: 4–6 months: ~150 mL/kg/day; a 5 kg baby ~750 mL/day; divide across feeds (~125 mL per feed).
    • From 6 months: introduce minced meats, chicken, fish, or egg yolk; transition to mixed foods as solids increase.
    • By 9–12 months: ~250 mL of milk twice daily; cereals and starchy foods introduced (baby cereals, mashed potatoes, rice, bread).
    • Fats are important for energy and nervous system development; ensure adequate fat intake via breast milk/infant formula.
    • Vitamin K injection at birth to prevent hemorrhagic disease; sunlight for vitamin D; iron stores sufficient for ~4–6 months; watch iron intake as brain growth accelerates around 6 months.
  • Toddlers (1–3 years)
    • Energy needs lower than during infancy; around 5500–6300 kJ/day by age 3.
    • Calcium, phosphorus, and iron are critical for bone development and blood health; ensure stores for growth.
    • Diet composition (daily servings): cereals 6–11 servings; meat alternatives 2–3 servings; milk and dairy 4 servings; vegetables/fruit combined; fats; salt limited to build long-term healthy habits; fiber intake equals age + 5 grams/day (example: 5-year-old = 10 g/day).
    • Offer a mix of protein sources (meat, poultry, fish without bones, dried beans/peas, eggs) and easy-to-chew options.
  • Young children (3–12 years)
    • Energy: 1500–? kj/day; protein: 16–28 g/day; fat and oils: choose lean meats and low-saturated-fat options; use low-fat dairy where possible.
    • Salt intake should be limited; dietary fiber aimed at age-related targets (age + 5 g per day rule can be used as a rough guide).
    • Calcium, phosphorus, and iron emphasized for bone growth and healthy blood production.
  • Teenagers and young adults
    • Growth spurts lead to higher energy needs; energy needs vary by sex and activity.
    • Girls: iron needs higher due to menstruation; boys generally require more minerals.
    • Protein: about 3 g per kg of body weight3\ \text{g per kg of body weight} in the form of meat, poultry, fish, eggs or soy.
    • Fats and oils: minimize saturated fats; prefer lean meats and plant oils.
    • Fiber: target 25−30 g/day25-30\ \text{g/day}.
    • Sugars: limit intake due to high kilojoule content and obesity risk; caffeine and alcohol should be moderated.
  • The elderly
    • Energy needs decrease, but nutrient needs remain similar to younger adults; poverty and illness can affect intake.
    • Maintain an ideal body weight with regular exercise; consider smaller, more frequent meals.
    • Protein: include at least two portions of lean meat, fish, eggs, liver, nuts/seeds, or legumes (soy/lentils) daily.
    • Fats: emphasize fats with essential fatty acids; maintain oils low in saturated fat; use low-fat dairy.
    • Calcium and phosphorus: emphasize minerals for bone health; supplementation may be needed from age 40 onwards.
    • Zinc deficiency can blunt appetite and taste; sources include meat, seafood, legumes, nuts, seeds, whole grains.
  • Illness and convalescence
    • Diet should support recovery; focus on vitamin C and zinc for wound healing; iron to support hemoglobin; ensure adequate fluids.
    • In restricted-fluid situations, emphasize fluids; in high-fever or gastric/ swallowing issues, use liquid diets; progression to light diets then to normal as tolerated.
    • Examples of diet progression:
    • Clear liquid, then light diet (poached/boiled eggs, toast, cereals, fruit jellies, etc.), then gradual progression to nutrient-dense foods (grilled meats, fish, eggs, stews, steamed vegetables, milk puddings).

1.7 The elderly (revisited)

  • Summary of goals
    • Ensure energy needs are met with nutrient-dense foods.
    • Maintain hydration; monitor mineral needs, especially calcium, phosphorus, and iron.
    • Manage bone health, cognitive health, and immune function through balanced intake.
  1. Nutritional Information Tables and Dietary Reference Intakes
  • RDA and DRI concepts
    • Recommended Dietary Allowances (RDAs): amounts sufficient to prevent deficiency diseases; different RDAs for various age/gender groups; for healthy people (not infants).
    • Dietary Reference Intakes (DRIs): based on RDAs but aimed to reduce chronic disease risk and provide nutritionally adequate intakes; used to evaluate group-level dietary adequacy.
  • Enrichment and Fortification
    • Enrichment: nutrients (often vitamins/minerals) added back to foods after processing (e.g., iron added back to refined white flour).
    • Fortification: deliberate addition of essential micronutrients to foods to improve dietary quality, regardless of whether nutrients were originally present (e.g., vitamin D in milk, iodine in salt, iron in breakfast cereals).
  1. Food Contamination (Chapter 9)
  • Microbial contamination
    • Microorganisms are everywhere (air, water, surfaces, animals, plants).
    • Contamination can occur during harvesting, storage, handling, and preparation; contaminated foods may taste/smell normal but still be toxic.
    • Signs of microbial contamination: bad odor, sliminess, discoloration, gas production in cans (bulging tins).
    • High-risk situations: inadequate refrigeration (≤5°C), leaving high-risk foods at room temperature for extended periods, large-ahead food prep increasing time in the danger zone (5–60°C).
    • Prevention: keep foods in the fridge, cook to safe temperatures, refrigerate leftovers promptly, use separate cutting boards for raw/ready-to-eat foods, avoid cross-contamination, sanitize surfaces (bleach solution: e.g., one teaspoon bleach per 2 liters water), store seafood properly, cook raw meat thoroughly (juices clear).
  • Physical contamination
    • Physical hazards include bone chips, metal fragments, hair, nails, insect/rodent waste.
    • Prevention: regular inspections, pest control, proper handling, good manufacturing practices, and pest controls.
  • Chemical contamination
    • Substances added during processing (e.g., additives) or contaminants from environment (mercury in seafood, aluminum exposure from utensils, pesticides on produce).
    • Metals from utensils/cans (galvanized containers, tin-coated cans) can contaminate foods.
    • Antibiotics/residues in animal foods (e.g., penicillin, tetracycline) may contribute to resistance with continual exposure.
  • Contamination prevention and food safety practices
    • Buy from clean, hygienic sources; maintain personal hygiene (handwashing with hot soapy water);
    • Use separate cutting boards for raw meats vs. ready-to-eat foods; store raw foods separately; inspect packaging for bulging tins or damaged containers; avoid open fruit and juice in damaged containers if unsafe.
  • Food poisoning: symptoms and treatment
    • Common symptoms: diarrhea, nausea, vomiting, abdominal cramps, fever, dehydration.
    • Treatment: for most mild cases, oral rehydration salts (sodium, glucose, and minerals) to prevent dehydration; rest the stomach and gradually reintroduce easily digestible foods (rice, white bread, potatoes, pasta, low-sugar cereals, lean meats).
    • Medical treatment: severe dehydration may require intravenous fluids; antibiotics if bacterial source confirmed and symptoms persist beyond 3–4 days; mushroom poisoning or pesticide exposure may require intensive care.
  • Cross-contamination prevention
    • Keep raw and cooked foods separate; wash hands, utensils, and surfaces after handling raw foods; use dedicated equipment for raw meats; avoid placing cooked food back on plates that held raw food.
    • Microwave-safe cleaning for wooden boards and cloths; sanitize boards and knives; rinse and clean surfaces thoroughly.

Notes on formatting in this document

  • All energy values and key numerical references are presented as explicit numbers or LaTeX-formatted expressions where appropriate, e.g.,
    • Protein energy: 1 g→16.8 kJ1\ \text{g} \rightarrow 16.8\ \text{kJ}
    • Fat energy: 1 g→37.8 kJ1\ \text{g} \rightarrow 37.8\ \text{kJ}
    • Carbohydrate energy yield is not explicitly given in the transcript; carbohydrate-related notes focus on energy role and storage as glycogen, and fiber effects.
  • The content above mirrors the topics and details from the transcript, including minor wording/typos as provided, but reorganized into a structured study notes format with clear bullet points and section headers for exam preparation.