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Questions and Answers
Which of the following is a simple carbohydrate?
Fiber can be fully digested by human digestive enzymes.
False
What is the primary function of carbohydrates in the body?
Energy
Soluble fiber dissolves in ______ and is partially digested by bacteria.
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Match the following types of fiber with their descriptions:
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What is the adequate intake (AI) for fiber per day for men aged 19-50?
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What is glycogen and where is it stored?
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Complex carbohydrates consist of chains of monosaccharides.
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What is the enzyme that breaks down sucrose into glucose and fructose?
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Lactose intolerance is due to high levels of lactase in the small intestine.
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What are the symptoms of lactose intolerance?
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Low levels of the small intestine enzyme called ___________ lead to lactose intolerance.
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Match the disaccharides with their corresponding enzymes.
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Which carbohydrate provides 4 kcal per gram?
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Insulin stimulates the release of glucose into the blood.
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What is the Recommended Dietary Allowance (RDA) for carbohydrates?
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After several hours post-meal, __________ is released to stimulate glucose release from the liver.
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Which of the following is an example of a whole grain?
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Diabetes mellitus is characterized by low blood glucose levels.
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List two food sources where one can obtain calcium.
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The outermost bran layers of grains contain most of the __________.
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Match the types of diabetes with their characteristics.
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Which type of fat is usually solid at room temperature?
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Unsaturated fatty acids have one or more carbon-carbon double bonds.
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What are the two main sources of dietary fat?
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1 gram of fat provides ______ calories.
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Match the types of fats with their characteristics:
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Which of these fats is known to be cardioprotective?
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Medium-chain saturated fats behave the same way as long-chain saturated fats.
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What is the role of fats in food?
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Which of the following represents essential fatty acids that humans cannot synthesize?
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Trans fats can increase LDL cholesterol levels and lower HDL cholesterol levels.
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What is the role of HDL particles in the body?
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Omega-3 fatty acids can be found in foods such as __________ and __________.
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Match the lipoproteins to their functions:
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What type of fat is known for its ability to lower LDL cholesterol while elevating HDL cholesterol?
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Atherosclerosis does not involve the buildup of plaques in artery walls.
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What is the recommended dietary intake for total fat as a percentage of total calories?
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Fats provide essential __________ vitamins, including vitamins A, D, E, and K.
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Which of the following foods is typically high in trans fats?
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Study Notes
Carbohydrate Needs
- Carbohydrates are essential for energy reserve and fuel for the brain and nervous system.
- They are readily available fuel compared to other nutrients.
Carbohydrate Structure
- Composed of one or more sugar units, containing carbon, hydrogen, and oxygen.
Carbohydrate Types
- Divided into simple and complex carbohydrates.
- Simple carbohydrates include monosaccharides (glucose, galactose, fructose) and disaccharides (maltose, sucrose, lactose).
- Complex carbohydrates include oligosaccharides (3-10 monosaccharides) and polysaccharides (large molecules with chains of monosaccharides).
Complex Carbohydrates: Starch, Glycogen, Fiber
- Starch: Storage form of glucose in plants.
- Glycogen: Storage form of glucose in animals and humans.
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Fiber: Indigestible residues of food composed of polysaccharides.
- Soluble Fiber: Dissolves in water, partially digested by bacteria in the large intestine, helps lower cholesterol, prevents type 2 diabetes, delays transit time (e.g., beans, peas, oats, barley, apples).
- Insoluble Fiber: Does not dissolve in water, not digested by bacteria in the large intestine, passes unchanged through the colon, promotes regular bowel movements, binds toxins (e.g., beans, whole grains, whole wheat/bran, vegetables, nuts).
Fiber Recommendations
- Adequate Intake (AI) for fiber: 38 g/day for men, 25 g/day for women (age 19-50).
- Canadians are not meeting their fiber requirements.
Carbohydrate Digestion & Absorption
- Mouth: Salivary amylase begins carbohydrate digestion.
- Small Intestine: Disaccharides are broken down by specific enzymes (sucrase, maltase) into monosaccharides, which are then absorbed.
Lactose Intolerance
- Caused by low levels of lactase, an enzyme in the small intestine. Lactose cannot be broken down, leading to symptoms like gas, abdominal distention, cramps, and diarrhea.
- Alternative calcium sources: tofu, legumes, salmon, broccoli.
- Not all dairy products have the same lactose content.
Functions of Carbohydrates
- Energy: 1 gram of carbohydrate provides 4 kcal.
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Other functions:
- Monosaccharides: Galactose is used by nerve cells and to make milk in breastfeeding women. Monosaccharides are also components of genetic material (DNA & RNA).
- Oligosaccharides: Involved in cell membrane signaling.
- Polysaccharides: Provide cushioning and lubrication in joints.
Blood Glucose Homeostasis
- Insulin: Released in response to rising blood glucose levels, stimulates glucose uptake by cells, glucose use for energy, and conversion of glucose to glycogen and fat.
- Glucagon: Released in response to low blood glucose levels, stimulates breakdown of liver glycogen and release of glucose to blood.
Diabetes Mellitus
- Characterized by high blood glucose levels.
- Type 1: Absolute insulin deficiency due to autoimmune destruction of insulin-secreting cells in the pancreas.
- Type 2: Insulin resistance and relative insulin deficiency.
- Gestational: First observed during pregnancy, increased risk of type 2 diabetes later in life.
Diabetes Concerns
- High blood sugar leads to long-term problems like fatigue, thirst, vision issues, peripheral nervous system damage, hunger, weight loss, infection, slow wound healing, and low blood sugar.
Carbohydrate Recommendations
- Consume enough carbohydrates to meet glucose needs.
- Choose the right types of carbohydrates for health and disease prevention.
- Recommended Dietary Allowance (RDA) for carbohydrate: 130 g/day.
- Acceptable Macronutrient Distribution Range (AMDR) for carbohydrate: 45-65% of total caloric intake.
Choosing Carbohydrates Wisely
- Canada's Food Guide: Recommends consuming whole grains, vegetables, and fruits while limiting highly processed foods, sugary foods and drinks, and other foods high in added sugars.
- Aim for ¼ of your plate to be whole grains.
Whole Grains vs. Refined Grains
- Whole Grains: Contain the entire kernel (germ, endosperm, bran), providing fiber, vitamins, minerals, and phytochemicals.
- Refined Grains: Processed to remove germ and bran, resulting in lower fiber, vitamin, mineral, and phytochemical content.
Added Sugars vs. Natural Sugars
- Added Sugars: Mono and disaccharides added by manufacturers, cooks, or consumers (e.g., honey, syrups, fruit juices).
- Natural Sugars: Found in whole fruits and vegetables.
- World Health Organization (WHO): Recommends limiting added sugar intake to less than 10% of total daily calorie intake.
Sources of Dietary Fat
- Animal sources: Meat, cheese, dairy
- Plant sources: Vegetable oils, nuts, avocados
- Hidden sources: French fries, pizza, pasta dishes, baked goods, salad dressings
Role of Fats in Food
- Contribute to texture, flavor, and aroma
- Aid in absorbing fat-soluble vitamins (A, D, E, K)
- Provide energy (1g of fat = 9 calories)
- AMDR (Acceptable Macronutrient Distribution Range) for fat: 20-35% of total calories
- Fats can have both positive and negative effects on health, depending on the amount consumed
Types of Fats (Lipids)
- Lipids are a group of organic molecules that are insoluble in water (hydrophobic).
- Lipids contain carbon, hydrogen, and oxygen.
- Fats are built from chains of fatty acids linked to glycerol.
- A triglyceride contains one glycerol molecule and three fatty acids.
- Fatty acid chains vary in length (4-7, 8-12, and >12 carbons).
Saturated Fats
- Contain all the hydrogen atoms possible, with no carbon-carbon double bonds.
- Primarily found in animal foods like meat and dairy products.
- Long-chain saturated fats are specifically linked to cardiovascular disease (CVD).
- Plant oils generally contain lower amounts of saturated fatty acids.
Unsaturated Fats
- Contain one or more carbon-carbon double bonds.
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Monounsaturated: One double bond, found in lean meat, olive oil, avocados, and nuts.
- May be cardioprotective.
- Thought to lower LDL ("lousy") cholesterol.
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Polyunsaturated: More than one double bond, primarily found in plant sources.
- Includes oils like canola oil, olive oil, etc.
Medium-Chain Saturated Fats
- Have 6-10 carbons.
- Behave differently than long-chain saturated fats.
- May have more beneficial effects on health.
- Digested and absorbed more quickly due to their shorter, relatively water-soluble nature.
- Bypass peripheral fat tissue, making them less likely to be stored as fat.
- Examples include coconut oil and palm oil.
Saturated vs. Unsaturated Fats
- Saturated: Solid at room temperature, primarily from animal sources and tropical plants (palm, coconut).
- Unsaturated: Liquid at room temperature, mostly from vegetable origins.
- Unsaturated fats are generally associated with a lower risk of disease, while saturated fats are linked to disease.
Essential Fatty Acids
- Defined as fatty acids that cannot be produced by the body and must be obtained from the diet.
- Omega-3 and Omega-6 fatty acids are essential.
- Two or more servings of fish per week are recommended for Omega-3 intake (2007 food guide).
- Other good sources of Omega-3: walnuts, canola oil, ground flaxseed, hemp, and fortified foods.
Trans Fat
- Unsaturated fats naturally go rancid quickly, leading to a shorter shelf life.
- Processed hydrogenation is used to make unsaturated fats more saturated, extending their shelf life.
- Partially hydrogenated oils are the result of this process, creating trans fats.
- Trans fats are found in many processed foods.
Other Lipids
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Phospholipids: Phosphorus-containing fats.
- Important component of cell membranes.
- Enable water and fat to mix, contributing to various cellular functions.
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Sterols:
- Cholesterol is a well-known sterol.
- Essential for cell membrane structure.
- Used to make bile for digestion.
- Precursor to vitamin D.
- Used in the production of sex hormones (estrogen and testosterone).
- Can be deposited in artery walls, leading to plaque buildup and heart disease.
Fat Digestion
- Bile emulsifies fats (breaks down into smaller droplets), making them easier to digest.
- Chylomicrons transport dietary fats from the small intestine to body cells via the lymphatic system and blood.
- Chylomicrons contain triglycerides, phospholipids, cholesterol, and fat-soluble vitamins.
- Triglycerides are broken down into fatty acids and glycerol before entering cells.
Lipoproteins
- Lipoproteins are blood transport molecules that carry triglycerides and cholesterol.
- They are surrounded by a shell of protein, phospholipids, and cholesterol.
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VLDL (Very Low Density Lipoproteins):
- Made in the liver and released into the blood.
- Function similarly to chylomicrons, transporting triglycerides.
- Remaining VLDL particles are either returned to the liver or converted into LDL particles.
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LDL (Low Density Lipoproteins):
- Deliver cholesterol to cells.
- High LDL levels increase the risk of heart disease.
- Considered "bad" cholesterol.
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HDL (High Density Lipoproteins):
- Transport cholesterol from cells back to the liver for excretion.
- Considered "good" cholesterol because it lowers blood cholesterol levels.
- The liver then uses cholesterol to make bile.
LDL vs. HDL
- LDL: Transports cholesterol from the liver to body cells. Lowering blood LDL levels is beneficial ("you want your low to be low").
- HDL: Transports cholesterol from cells to the liver for excretion. Increasing blood HDL levels is beneficial ("you want your high to be high").
Food Fat & Body Fats
- Saturated Fats: Increase LDL levels.
- Monounsaturated Fats: Lower LDL and maintain HDL levels.
- Polyunsaturated Fats: Lower LDL and elevate HDL levels.
- Trans Fats: Increase LDL and lower HDL levels.
Functions of Fat in the Body
- Food Flavor & Texture: Contributes to smooth, melty, tenderizing qualities, and aroma molecules.
- Satiation: Creates a feeling of fullness, but not until after digestion begins.
- Energy: Energy-dense and stored for later use.
- Essential Fatty Acids: Provides omega-3 and omega-6 fatty acids, crucial for various bodily functions.
- Fat-soluble vitamins: Transports vitamins A, D, E, and K.
- Cell Membranes: Integral to the structure of cell membranes, particularly in the brain and spinal cord.
- Protection: Physical padding and insulation for organs and body tissues.
Lipids and Disease
- The amount and type of fat consumed can significantly affect health.
- Insufficient fat intake can hinder growth, vision, and other physiological functions.
- Excessive fat intake can lead to:
- Increased total calorie consumption.
- An elevated risk of cardiovascular disease and cancer (specifically from trans and saturated fats).
Heart Disease
- Atherosclerosis: A cardiovascular disease characterized by the buildup of fatty material in artery walls (atherosclerotic plaques).
- Atherosclerotic plaque formation occurs after blood vessel injury, inflammation, and LDL cholesterol oxidation.
- Plaques narrow blood vessels, restricting blood flow and reducing oxygen and nutrient delivery to tissues.
Heart Disease Recommendations
- Dietary Reference Intake (DRI):
- Total fat: 20-35% of total calories.
- Minimize intake of cholesterol, saturated fats, and trans fats.
Making Wise Food Choices
- Choose foods low in saturated fats.
- Opt for lean protein sources (lean meat, chicken, etc.).
- Employ cooking methods that minimize added fats (baking, broiling, steaming instead of frying).
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Description
Explore the essential role of carbohydrates in energy production and their structure in this quiz. Learn about different types of carbohydrates, including simple and complex forms, and their significance in human nutrition. Test your understanding of starch, glycogen, and fiber.
