Nutrition and Dietary Reference Intakes Quiz

Dietary Reference Intakes (DRIs)

• DRIs are reference values for planning and assessing nutrient intakes in healthy people.
• They are a scientific basis for food guides and nutritional guidelines.
• A daily 90mg vitamin C intake requires 7 servings of fruits and vegetables.
• DRIs are co-developed by experts in Canada and the U.S., while the UK uses Dietary Reference Values (DRVs).

Rationale Behind Food Groups

• Food groups help meet nutritional needs efficiently.
• Recommended servings are based on nutrient requirements for health (scientific research).
• Examples include fruits/vegetables, proteins, grains, and dairy/alternatives.
• The goal is a balanced intake of vitamins, minerals, and macronutrients.

Food Guides

• Food guides help individuals make informed food choices.
• Recommendations are based on DRIs or DRVs.
• Following guides helps meet nutrient needs, prevent deficiencies, and maintain health.

Scientific Evidence Behind Serving Suggestions

• DRIs are based on decades of research.
• DRIs get updated with new nutrition research.
• Guidelines assist healthy food choices when shopping/planning meals.

History of DRIs

• Early DRIs focused on preventing deficiency diseases (e.g., scurvy).
• Now, the focus is on preventing chronic diseases (e.g., CVD, type 2 diabetes).

Objectives of DRIs

• Prevention of deficiency diseases.
• Reduced risk of chronic diet-related diseases.
• Establishing safe upper limits for nutrients to avoid toxicity.

Nutrient Intake Standards

• Group 1: Focuses on deficiency prevention and safe supplement use.
• EAR: Meets the nutrient needs of 50% of the population.
• RDA: Meets the needs of 98% of the population.
• AI: Used when RDA cannot be determined.
• UL: The maximum intake unlikely to cause toxicity.
• Group 2: DRIs for energy and macronutrients (carbohydrates, lipids, proteins).

Nutrient Standards by Gender & Life Stage

• Men have 10 lifestages, women 16 (due to pregnancy/lactation).
• Pregnancy significantly increases nutrient needs (e.g., iron from 8mg to 27mg).

DRIs for Most Nutrients

• Sodium AI is 1500 mg/day, but North American average intake is ~3400 mg/day (due to processed foods).

Summary of DRIs

• Optimal intake of nutrients lies between RDA and UL on a graph (Nutrient intake on x-axis, Health on y-axis).

DRIs for Energy and Macronutrients

• EER calculates energy needs based on activity, height, weight, age, and gender.

Acceptable Macronutrient Distribution Ranges (AMDRs)

• Carbohydrates: 45-65% of energy intake.
• Fat: 20-35%.
• Protein: 10-35%.
• These ranges reduce chronic disease risk and ensure adequate energy intake.

Who Uses DRIs?

• Registered dietitians frequently use DRIs to assess and plan diets.
• General practitioners often refer patients to dietitians.

Becoming a Registered Dietitian

• Quebec's dietetics are regulated by the Ordre professionnel des diététistes du Québec (OPDQ).
• Dietitians of Canada provides information in other provinces.

Food Industry and DRIs

• The Nutrition Facts Table is based on DRIs and regulated by the CFIA.
• Mandatory since 2007 in Canada.

Nutrition Facts Table

• Contains 13 nutrients (e.g., calcium, iron, sodium).
• Daily Values are based on a 2000 kcal diet and represent the percentage proportion by serving.

Grains Food Group

• Grains are seeds with a germ, endosperm, and bran.
• High in carbohydrates, fiber, folate, vitamin E, magnesium, and iron.
• Whole grains contain all parts; refined grains (e.g., white bread) only have endosperm.

Meat & Alternatives Food Group

• Meat provides protein, B6/B12, iron, and zinc.
• Alternatives include legumes, nuts, and seeds.
• Legumes/nuts are energy-dense, rich in nutrients (necessary for developing embryos).

Milk & Alternatives Food Group

• Includes milk, cheese, yogurt.
• Rich in protein, riboflavin, vitamins D/B12, and calcium.
• Milk in Canada has fortification with vitamins A and D.

Vegetables and Fruit Food Group

• Includes fruits/vegetables (botanically fruits).
• Rich in vitamins, minerals, fiber, antioxidants.
• Mushrooms are examples of non-plant members.

Canada’s Food Guide

• Simplifies recommendations for different age/gender groups into serving suggestions.
• Fruits and vegetables have the most recommended servings.

Fruits & Vegetables: Why So Nutritious?

• Rich in vitamins, minerals, fiber, antioxidants.
• Designed by nature for animal nourishment and seed dispersal.

Food Designed by Nature

• Fruits encourage seed dispersal by attracting animals.
• Seeds, eggs, milk provide nourishment for developing organisms.

Introduction to Basic Concepts in Chemistry

• Matter: Has mass, occupies space.
• Elements: Pure substance of only one type of atom.
• Atoms: Smallest unit of an element, retains properties.
• Molecules: Two or more atoms bonded together.
• Ions: Atoms/molecules with a charge (gained/lost electrons).
• Compounds: Different types of atoms bonded together.

Key Chemistry Concepts for Nutrition and Molecular Gastronomy

• Solutions: Homogenous mixtures of substances.
• Solubility: Ability of a substance to dissolve in a solvent.
• Enzymes: Catalyze chemical reactions (essential for digestion).
• pH Scale: Measures acidity/alkalinity (0-14, 7 is neutral).

Digestive System

• Breaks down food for nutrient absorption.
• Involves mouth, esophagus, stomach, small intestine, and large intestine.

Circulatory System

• Distributes absorbed nutrients.
• Involves blood vessels and the heart.

Periodic Table of Elements

• 25 elements are essential for life.
• Humans have a similar chemical composition to plants (because of consuming plants and foods).

Human Body Composition

• Composed of 23+ elements and trillions of atoms.
• Earth contains 92 elements and many atoms.

Molecules and Compounds

• Molecules: Atoms bonded together in a set arrangement.
• Compounds: Molecules made up of different elements.
• Oxygen gas is a molecule (but not a compound as it contains only one element).

Atoms and Subatomic Particles

• Protons: Positively charged, in the nucleus.
• Neutrons: No charge, in the nucleus.
• Electrons: Negatively charged, orbit the nucleus.
• Valence shell: Outermost shell; determines chemical behavior.
• Valence electrons: Electrons in the valence shell; full valence shells make an element inert (no bonds).

Chemical Bonds

• Covalent Bonds: Sharing electrons to fill valence shells; strongest bonds (e.g., solid table).
• Ionic Bonds: Transferring electrons, creating charged ions; weaker than covalent bonds; dissociate in water (e.g., table salt).

What is a Solution?

• An evenly distributed mixture of two or more compounds.
• Solvent: Primary component (e.g. water).
• Solute: Lesser component dissolved in the solvent (e.g. nutrients in plasma).
• Blood plasma is an aqueous solution, carrying nutrients to body cells via capillaries.

Electronegativity

• Degree of an atom's attraction for electrons in a bond.
• Oxygen is highly electronegative, pulling electrons and creating partial charges.
• Hydrogen bonds form between partial positive hydrogen and negative oxygen in polar molecules.

Polar Molecules and Hydrogen Bonds

• Polar Molecules: Molecules with partial charges (uneven electron sharing).
• Hydrogen Bonds: Weak bonds between polar molecules' partial charges.
• Water forms hydrogen bonds with polar molecules, aiding in dissolving them.

Solubility of Solutes

• Solubility describes how easily a compound dissolves in a solvent.
• Non-polar molecules (like lipids) do not dissolve in water (e.g., oil and water).

Starch Solubility

• Starch: Long glucose chains in plant-based foods.
• Gelation: Starch swells and unfolds when heated, dissolving.
• Binding water molecules thickens mixtures (e.g., sauces).

Cooking and Starch

• Pasta water starch forms a glue-like substance due to hydrogen bonding, improving sauce adhesion.

Enzymes

• Proteins that speed up chemical reactions (e.g., digesting nutrients).
• Specific: bind specific substrates. Lactase binds lactose.
• Structure: Maintained by hydrogen bonds (changes in pH affect).

The pH of Fluids

• pH measures hydrogen ion concentration, impacting acidity and enzyme function.
• Digestive system pH varies (mouth 6.4, stomach 1, small intestine 8) affecting enzyme activity.

The pH Scale

• Ranges from 0 (acidic) to 14 (alkaline); Each whole number represents a tenfold change in hydrogen ion concentration.
• Impacts bonds: Hydrogen ions disrupt hydrogen bonds, affecting protein/enzyme structures.

Influence of pH on Protein Structure

• Adding lemon juice to milk causes curdling by increasing hydrogen ions, disrupting casein proteins and causing aggregation.

Digestive System Overview

• Digestive system organs work together, like an assembly line, to digest food and deliver nutrients to cells.

Cells, Tissues, and Organs

• Cells are the body's basic building blocks.
• Tissues are groups of similar cells working together (epithelial, connective, muscle, neural).
• Organs are tissues functioning together.
• Organ systems are organs working in a coordinated manner.

Types of Tissues in the Digestive System

• Epithelial tissue lines the digestive tract, absorbs nutrients, and secretes enzymes.
• Connective, muscle, and nervous tissue assist in moving food, provide structure, and transmit signals.

Digestive Organ System Components

• Main organs: Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus.
• Accessory organs: Salivary glands, gallbladder, pancreas, liver.
• Lumen: The hollow area in the digestive tract.
• Transit time: Food’s time in the digestive tract (24-72 hours).

Functions of the Digestive System

• Secretion of enzymes, hormones, and mucus to aid digestion and protect tissues.

The Mouth and Stomach

• Mechanical digestion (physical breakdown) and chemical digestion (enzyme breakdown) begin in the mouth.
• Stomach churns food, mixing it with acids and enzymes, into chyme.

Small Intestine Architecture

• Villi and microvilli increase surface area for nutrient absorption.
• Nutrients absorbed by epithelial cells enter blood or lymph vessels.
• High cell turnover (malnutrition leads to impaired absorption e.g., diarrhea).

The Digestive System Meets the Circulatory System

• Absorption: Nutrients move from the GI tract into blood/lymph vessels.
• Water-soluble nutrients move via blood to the liver.
• Fats enter lymphatic system to travel to the bloodstream.

Accessory Organs

• Liver, gallbladder, pancreas aid digestion by releasing substances into the small intestine.

Nutrient Delivery

• Hepatic portal vein delivers absorbed nutrients to the liver before the rest of the body.

Elimination and Gut Flora

• Elimination: Solid waste removed.
• Gut flora contains 400+ bacterial species that help break down fiber and produce beneficial compounds.
• Probiotics provide live bacterial cultures; prebiotics contain fiber to nourish gut bacteria.

The Network of Blood Vessels

• Heart pumps blood through the circulatory system.
• Blood vessels include arteries, arterioles, capillaries, venules, and veins.

Nutrient Exchange Between Blood and Cells

• Capillaries facilitate nutrient/oxygen delivery to cells and waste removal.

Overview of Carbohydrates

• Carbohydrates are a significant energy source, impacting health based on type and amount.
• Simple/complex carbohydrates differ in their roles.

The Making of Food Calories

• Plants store energy as glucose, which we consume for energy.
• Carbohydrates/proteins = 4 kcal/g; Lipids = 9 kcal/g.
• Calories on labels are kilocalories(kcal), but commonly labeled as "big Calories".

Simple Carbohydrates and Sweeteners

• Monosaccharides (glucose, fructose, galactose) are simple sugars, with glucose being most important for the body.
• Disaccharides (lactose, maltose, sucrose) are common sugars; sucrose is widely consumed, contributing to excessive sugar intake.
• Excessive simple sugars are linked to obesity/type 2 diabetes.
• Alternative sweeteners (Stevia, Splenda, sugar alcohols) offer sweetness with fewer calories but can cause digestive issues.

Complex Carbohydrates

• Starch: Plants store glucose as starch, broken down to glucose in digestion.
• Amylose: Digests slowly, slow rise in blood glucose.
• Amylopectin: Digests quickly, fast rise in blood glucose.
• Sources: Grains, legumes, and vegetables.
• Glycogen: Body’s storage form of glucose in liver/muscles, rapid energy release.
• Fiber:
• Soluble: Dissolves in water, slows digestion, traps glucose/cholesterol, feeds gut bacteria (prevents diseases).
• Insoluble: Adds bulk to stool (promotes healthy bowel movements).

Digestion of Carbohydrates

• Enzymes (salivary amylase, pancreatic amylase, maltase, sucrase, lactase) break down carbohydrates.
• End products (mainly glucose, some fructose/galactose) are absorbed into the bloodstream and converted to glucose in the liver.
• Lactose intolerance: Insufficient lactase results in digestive issues.

Carbohydrates and Disease

• Blood glucose regulation: Insulin/glucagon maintain blood glucose levels.
• Types of Diabetes:
• Type 1: Autoimmune; pancreas doesn't produce insulin.
• Type 2: Insulin resistance due to diet/inactivity.
• Gestational: Occurs during pregnancy.

Recommendations for Carbohydrate Intake

• RDA for glucose: 130g/day for adults (minimum needed).
• AMDR for carbohydrates: 45-65% of total calories (approximately 225-325g for a 2000kcal diet).
• Fiber recommendations: 14g fiber per 1000 kcal.

Key Issues with Modern Carbohydrate Intake

• Overconsumption of simple sugars from processed foods/sugary drinks is linked to diseases.
• Low fiber intake from pulses/vegetables is common.

Lipids

• Lipids are important for flavor, texture, nutrient absorption, and satiety.
• Fat cells provide organ protection, insulation, and cushioning.

Types of Lipids

• Fatty acids are the building blocks; Chain length and saturation affect their properties. Types include:
• Saturated fatty acids: Straight chains, solid at room temperature.
• Unsaturated fatty acids: Bent chains, liquid at room temperature; Monounsaturated vs. Polyunsaturated.
• Omega fatty acids (omega-3/6): Essential for brain health/reducing inflammation; found in fish, walnuts, flaxseeds.
• Trans fatty acids: Man-made (hydrogenation); harmful for heart health.

Triglycerides and Phospholipids

• Triglycerides: Common form of fat in food/body.
• Phospholipids: Similar to triglycerides, have a phosphate group; form cell membranes, act as emulsifiers.

Cholesterol

• Cholesterol lacks fatty acids and is not broken down.
• Plays a role in cell membranes, vitamin D/hormone synthesis.
• Dietary source found in animal products; liver also makes cholesterol.

Digestion and Absorption of Lipids

• Digestion starts in mouth/stomach, small intestine is major site.
• Bile breaks lipids into micelles.
• Pancreatic lipase breaks triglycerides into free fatty acids and monoglycerides.
• Short/medium-chain fatty acids are absorbed directly into the bloodstream.
• Long-chain fatty acids are packaged into chylomicrons for transport to the bloodstream.

Lipoproteins

• Lipoproteins transport lipids through the bloodstream. Types include:
• Chylomicrons: Transport triglycerides from intestines.
• VLDLs: Transport triglycerides made by the liver to fat cells.
• LDLs: Deliver cholesterol to cells ("bad cholesterol").
• HDLs: Remove cholesterol from cells ("good cholesterol").

Cardiovascular Disease (CVD)

• CVD includes heart and blood vessel diseases, often caused by plaque buildup in arteries.
• Factors include high LDL cholesterol, high glucose, tobacco use.
• Plaque narrows arteries, increasing risk of heart attacks, strokes, or organ damage.
• Reducing CVD risk involves increasing soluble fiber, moderating fat intake, and increasing omega-3s.

Recommendations for Lipid Intake

• AMDR for fat: 20-35% of total calories.
• Limit saturated fat to less than 10% of calories.
• Avoid trans fats.

Proteins

• Proteins are complex molecules composed of amino acids.
• 20 amino acids; 9 essential (must be in diet), 11 nonessential.
• Amino acids form polypeptide chains, linked by peptide bonds.
• Protein shape is essential for its function.
• Protein structures are denatured by environmental changes (e.g., temperature, pH).

Protein Synthesis

• Based on DNA instructions, linking amino acids in specific sequences.
• DNA is transcribed into mRNA; mRNA directs ribosomes to assemble amino acids into polypeptides.
• Protein folding creates functional proteins.

Protein Digestion and Absorption

• Protein digestion begins in the stomach by:
• Hydrochloric acid (HCl) denaturing proteins.
• Pepsin breaking proteins into smaller polypeptides.
• Continues in the small intestine with pancreatic enzymes.
• Amino acids are absorbed into the bloodstream through the hepatic portal vein.

Protein Turnover and Nitrogen Balance

• Protein turnover: Recycling of proteins into amino acids.
• Nitrogen balance: Intake equals loss (growth, pregnancy, recovery, positive).
• Negative nitrogen balance happens during starvation/trauma.
• Proteins can be broken down for energy by removing the amino group.

Protein in Food and DRIs

• Protein requirements (EAR, RDA) depend on body weight.
• High-quality proteins contain all essential amino acids (e.g., animal proteins).
• Low-quality proteins lack some essential amino acids (e.g., plant proteins).
• Protein complementation is achieving a full amino acid profile by combining different plant proteins.

Diseases Involving Proteins

• Allergies: Immune system reacting to proteins. Common allergens: nuts, shellfish, milk, eggs, wheat.
• Celiac disease: Autoimmune response to gluten; damages intestinal lining.
• NCGS (Non-Celiac Gluten Sensitivity): Symptoms like celiac but without intestinal damage.

Vitamins

• Vitamins are non-energy-yielding micronutrients, essential for chemical reactions.
  • Fat-soluble: A, D, E, K (stored in the body).
  • Water-soluble: B complex, C (not stored).

Fat-Soluble Vitamins

• Vitamin A: Maintains cell and corneal health, vision. Sources: animal/plant.
• Vitamin D: Essential for bone health, supports cell growth. Sources: Sun/fortified foods.
• Vitamin E: Protects cells from damage (antioxidant). Sources: Vegetable oils, nuts, seeds.
• Vitamin K: Needed for blood clotting, bone health. Sources: Leafy greens, bacteria.

Water-Soluble Vitamins

• B Vitamins: Act as coenzymes in energy metabolism/DNA synthesis. Types include Thiamin (B1), Riboflavin (B2), Niacin (B3), Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin.
  • Folate: Crucial for cell function, preventing neural tube defects.
  • Vitamin B12: Essential for nerve cell maintenance.
  • Can be deficient due to lack of intrinsic factor.
• Vitamin C: Crucial for collagen formation, an antioxidant.
  • Scurvy causes weakened tissues, loose teeth, poor wound healing.

Minerals

• Essential elements, major (large amounts) and smaller amounts required (trace minerals).
  • Calcium: Needed for bones, teeth, muscle function, clotting.
  • Phosphorus: Essential in bone and tooth formation, energy production.
  • Magnesium: Important for bone health, muscle function, nerve transmission, energy production.
  • Sodium/Potassium: Fluid balance, nerve transmission, muscle function.
  • Iron: Essential for oxygen transport (hemoglobin).
  • Iodine: For thyroid hormone production (metabolism).
  • Zinc: Crucial for immune function, wound healing, protein synthesis.
  • Selenium: Antioxidant, immune support.
  • Copper: Involved in iron metabolism, collagen, energy production.

Water, Metabolism, and Energy

• Water is vital for life, functioning in transport, temperature regulation, and waste elimination.
• Osmosis: Water movement across membranes, balancing solute concentrations.
• Kidneys: Filter blood, regulate water output.
• Metabolism: Sum of body's chemical reactions to produce energy.
  • Anabolic: Building molecules.
  • Catabolic: Breaking down molecules.
• Basal Metabolic Rate (BMR): Measure of resting energy expenditure (breathing, circulation).
• ATP (adenosine triphosphate): Energy currency in cells.
• Cellular respiration generates ATP from nutrients.
• Energy balance maintains a stable weight (calories in = calories out).

Food Safety and Sustainability

• Food safety focuses on reducing foodborne illness.
• Pathogens (e.g., bacteria, viruses) cause foodborne illnesses from food or via toxins.
• Food preservation helps reduce food contamination risks (pasteurization, canning, refrigeration, freezing, irradiation).
• Key agencies (Health Canada, CFIA, PHAC) ensure food safety.

Test your knowledge on Dietary Reference Intakes (DRIs) and their role in nutrition. This quiz covers the major food groups, Recommended Dietary Allowances (RDAs), Estimated Average Requirements (EARs), and the goals of food guides. Challenge yourself to understand the importance and classification of nutritional needs.