Food and Nutrition Study Notes

Nutrition and Its Importance for Health and Wellbeing

  • Definition of Nutrition

    • Nutrition refers to the process by which living organisms obtain and utilize food to support their growth, maintenance, and overall health.

    • Nutrition matters for health and wellbeing because it influences bodily functions, resilience against disease, energy levels, and overall quality of life.

  • High Processed Foods

    • Importance of Natural Foods: It is crucial to keep food as close to its natural state as possible.

    • Definition of Ultra Processed Foods: Foods that are not essential for a nutritional diet.

    • Health Risks Associated with Ultra Processed Foods:

    • Main driver of overweight and obesity.

    • Linked to heart disease, type 2 diabetes, and certain cancers.

    • Research studies show a correlation between the consumption of ultra processed foods and increased risk of:

      • Metabolic syndrome.

      • Frailty.

      • Irritable bowel syndrome.

      • Cardiometabolic diseases.

Six Classes of Nutrients and Their Roles

  • Carbohydrates

    • Definition: Carbohydrates are organic compounds consisting of carbon, hydrogen, and oxygen, serving as the body's primary energy source.

    • Role: They provide ready energy for bodily functions.

    • Food Sources: Bread, rice, grains, and fruits.

    • Energy Content: Each gram of carbohydrates contains approximately 17 ext{kJ} (or 4 ext{calories}).

  • Proteins

    • Definition: Proteins are organic macronutrients made up of amino acids, including carbon, hydrogen, oxygen, and nitrogen.

    • Role: Building blocks for muscle growth and repair; support immune function and form enzymes and hormones.

    • Food Sources: Eggs, tofu, fish, meat, dairy, nuts, and seeds.

    • Energy Content: Each gram contains approximately 17 ext{kJ} (or 4 ext{calories}).

  • Fats/Lipids

    • Definition: Fats are organic compounds primarily composed of carbon, hydrogen, and oxygen.

    • Role: Provide insulation and protection for organs; supply concentrated energy and form cell membranes.

    • Food Sources: Unsaturated fats in nuts, seeds, oils, and fish; saturated fats in some animal products and plant oils.

    • Energy Content: Each gram contains approximately 37 ext{kJ} (or 9 ext{calories}).

  • Vitamins

    • Definition: Vitamins are organic micronutrients not yielding energy but playing crucial roles in bodily functions.

    • Role: Facilitate the release of energy from macronutrients and participate in numerous physiological activities.

    • Special Characteristics: Each of the 13 vitamins has distinct functions; they are vulnerable to destruction by heat, light, and chemicals.

    • Preservation: Cooking methods such as moderate heating and minimal water usage help retain vitamins.

  • Minerals

    • Definition: Inorganic micronutrients that contribute to various physiological functions in the body.

    • Role: Aid in fluid balance, support bone structure, enable nerve transmission, and assist in muscle contraction.

    • Essential Minerals: 16 minerals are essential, including calcium, phosphorus, potassium, sodium, and magnesium.

    • Impact of Food Processing: Some substances can interfere with the absorption of minerals, which can also be lost during food refining.

  • Water

    • Definition: An inorganic compound composed of hydrogen and oxygen essential for life.

    • Role: Transports nutrients and waste, maintains blood pressure and volume, lubricates joints, and regulates body temperature.

Energy in Food: Kilojoules and Kilocalories

  • Measurement of Energy

    • Energy from macronutrients (carbohydrates, proteins, fats) is measured in kilojoules (kJ) and kilocalories (kcal).

    • Conversion: 1 ext{kcal} = 4.2 ext{kJ}.

  • Example Calculation of Energy

    • Consider a meal consisting of a bagel and 50g of cottage cheese:

    • Carbohydrates: 46.9 g yields 46.9 imes 17 = 797 ext{kJ}.

    • Protein: 15.35 g yields 15.35 imes 17 = 260.95 ext{kJ}.

    • Fat: 2 g yields 2 imes 37 = 74 ext{kJ}.

    • Total Energy of Meal: 797 + 260.95 + 74 = 1133 ext{kJ} (equivalent to 270 kcal).

    • Percentage Composition of Macronutrients:

    • Carbohydrates: 70%

    • Protein: 27%

    • Fats: 3%

    • Recommendation: Keep fat intake under 35% per meal.

Concepts of Nutritional Guidelines

  • Adequacy

    • Definition: A diet that provides enough energy and essential nutrients to meet daily needs.

    • Importance: Prevents deficiencies, such as iron-deficiency anemia, which leads to fatigue and other symptoms.

  • Balance

    • Definition: Consuming appropriate amounts from all food groups to avoid overconsumption and ensure comprehensive nutrient intake.

    • Example: Meat is rich in iron but low in calcium; milk is rich in calcium but low in iron. A balanced diet includes diverse food groups to meet nutrient requirements.

  • Moderation

    • Definition: Limiting foods high in fats and added sugars while occasionally enjoying them.

    • Benefit: Helps maintain healthy weight and improves overall nutrient density.

  • Variety

    • Definition: Eating different foods regularly from food groups to improve nutrient adequacy and minimize risks from specific foods.

    • Key Benefit: Enhances enjoyment of food and helps reduce potential exposure to harmful substances.

  • Nutrient Density

    • Definition: Choosing foods that provide a high ratio of nutrients to calorie content.

    • Example: Low-fat milk has the same calcium as cheddar cheese but with fewer kilojoules.

  • Kilojoule Control

    • Definition: Managing energy intake to match the body’s needs.

    • Impact: Helps maintain healthy weight and meet nutrient needs without excessive kilojoules.

New Zealand Healthy-Eating Guidance

  • Purpose: Dietary guidelines aim to promote health and reduce diet-related diseases among individuals and populations.

  • Practical Advice: Recommendations focus on the types and amounts of food to consume to ensure nutrient needs, maintain a healthy weight, and minimize disease risks.

  • Key Statements:

    • Eat plenty of fruits and vegetables (at least 2 fruits and 5 vegetables a day).

    • Favor water as the primary beverage.

    • Limit alcohol consumption.

    • Encourage physical activity by minimizing sedentary behavior.

Assessing Diets

  • Nutritional Assessment: Evaluates health through the lens of nutrition, determining malnutrition status.

  • Data Collection Methods:

    • Dietary Information: Methods such as 24-hour recalls, food frequency checklists, food records, and diet history.

    • Historical Information: Includes health history, medications, supplements, and socio-economic factors.

    • Anthropometric Data: Measurement of physical characteristics such as height, weight, and body composition.

    • Physical Assessment: Evaluation for visible signs of nutrient deficiencies or excesses.

    • Laboratory Tests: Used to identify early signs of malnutrition or imbalances, analyzing blood, urine, or tissue samples.

Macronutrients and Micronutrients

  • Macronutrients: Nutrients needed in larger amounts providing energy.

    • Carbohydrates: Main energy source; sources include grains and fruits.

    • Proteins: Essential for tissue building and repair; sources include meat and legumes.

    • Fats: Concentrated energy sources; sources include nuts and oils.

  • Micronutrients: Needed in small amounts; do not provide energy but essential for processes in the body.

    • Vitamins: Both water-soluble (B vitamins and C) and fat-soluble (A, D, E, K) play significant roles in metabolism and health.

    • Water-soluble: Functions include energy metabolism.

    • Fat-soluble: Functions include antioxidant protection.

    • Minerals: Important for various bodily functions, e.g., iron (oxygen transport), calcium (bones), iodine (thyroid hormones).

Nutrient Reference Values

  • EAR: Estimated Average Requirement; meets needs of approximately 50% of the population.

  • RDI: Recommended Dietary Intake; set to cover the needs of 98% of the population and only for certain nutrients.

  • AI: Adequate Intake; reflects average intake among healthy populations when RDI or EAR cannot be determined.

  • Upper Levels of Intake: Risks from overconsumption of nutrients, especially through supplementation alongside a balanced diet.

Digestive Health and Nutrient Absorption

  • Digestive Tract Overview:

    • Mouth: Begins digestion through chewing and saliva.

    • Oesophagus: Transports food via peristalsis.

    • Stomach: Mixes food into chyme and begins protein digestion.

    • Small Intestine: Major site for digestion and absorption.

    • Large Intestine: Absorbs water and compacts waste.

  • Chemical Breakdown:

    • Acids: Hydrochloric acid (HCl) in stomach activates digestion.

    • Enzymes: Breakdown macronutrients (e.g., amylase, pepsin, lipase).

    • Bile: Emulsifies fats for enhanced digestion by lipase.

  • Nutrient Absorption Mechanisms:

    • Simple Diffusion: Small molecules cross freely.

    • Facilitated Diffusion: Carrier proteins assist larger molecules.

    • Active Transport: Nutrients are absorbed against concentration gradients using energy.

  • Transport Routes:

    • Blood: Water-soluble nutrients enter through capillaries.

    • Lymph: Fat-soluble nutrients enter as chylomicrons, traveling through lymphatics.

  • Functions of Gut Microbiome: Supports gut health and immunity; can be influenced by diet and medication; prebiotics and probiotics are essential for maintaining gut flora.

Evaluating Reliable Nutritional Information

  • Criteria for Determining Reliability:

    • Who: Authors’ qualifications and expertise.

    • When: Recency and updates to the data.

    • Where: Domain types indicating reliability, such as .gov, .edu, .org.

    • Why: Purpose of the information—public service vs. commercial interests.

    • What: Consistency with other reliable sources.

  • Sources of Reliable Information:

    • Review articles: Comprehensive examinations of subjects.

    • Journals: Detailed study results and methods.

    • Indexes: Lists of research articles on specific topics.

Glossary of Key Terms

  • Nutritional Genomics: The science of how nutrients and genes interact with diet and disease.

  • Enemy-Based Nutrition: Grounded in high-quality, evaluated research rather than anecdotal evidence.

  • Correlation: Changes in variable relationships (positive or negative).

  • Peer Review: Process of ensuring quality and validity in published studies.

  • Laboratory-Based Studies: Controlled experiments examining specific variables.

  • Human Intervention Trials: Research involving specified regimens for human subjects.

  • Placebos: Used in clinical trials as non-active treatment for comparison.

Course Learning Objectives

  • General Understanding: Topics covered will include nutrients and their roles, energy in food, healthy eating guidelines, diet assessment, digestion, and critical evaluation of nutrition information.

  • Week 5 Assignment: A multiple-choice test encompassing all covered materials.