Nutrition 1 - Macronutrients Flashcards
What is nutrition?
The science of foods and their actions within the body, including their relationship to health and disease.
What are the six classes of nutrients?
Carbohydrates, proteins, lipids, vitamins, mineral salts, and water.
What are macronutrients?
Nutrients required in large amounts (grams/day), including carbohydrates, proteins, and fats.
What are micronutrients?
Nutrients required in small amounts (mg or μg daily), including vitamins and minerals.
Which macronutrients provide energy?
Carbohydrates (4 kcal/g), proteins (4 kcal/g), and fats (9 kcal/g).
How is energy measured in nutrition?
In kilocalories (kCal) or kilojoules (kJ), where 1 kCal = 4.2 kJ
What is the recommended daily calorie intake?
~2,000 kcal/day for women and ~2,500 kcal/day for men (NHS guidelines).
What happens when energy intake exceeds expenditure?
Weight gain, obesity, and increased risk of chronic diseases.
What happens when energy intake is too low?
Weight loss, nutrient deficiencies, and metabolic imbalances.
What are carbohydrates?
Organic compounds composed of carbon, hydrogen, and oxygen, serving as the body’s primary energy source.
What are the three main types of carbohydrates?
Monosaccharides, disaccharides, and polysaccharides.
Give examples of monosaccharides.
Glucose, fructose, galactose
How is excess glucose stored?
As glycogen in the liver and muscle cells.
Which hormones regulate blood glucose?
Insulin (lowers glucose) and glucagon (raises glucose).
Give examples of disaccharides and their components.
Sucrose (glucose + fructose), lactose (glucose + galactose), maltose (glucose + glucose).
What are polysaccharides?
Large carbohydrate molecules composed of many monosaccharide units.
Give examples of polysaccharides.
Starch (plants), glycogen (animals), cellulose (fiber).
How are carbohydrates digested?
Broken down by amylase enzymes into monosaccharides for absorption.
What is dietary fiber?
Indigestible plant polysaccharides that aid digestion and regulate cholesterol
What are the health benefits of fiber?
Prevents constipation, lowers cholesterol, reduces risk of heart disease and colon cancer.
What is the glycaemic index (GI)?
A measure of how quickly a carbohydrate raises blood sugar levels.
What are high-GI foods?
Processed carbs, white bread, potatoes, watermelon (cause rapid blood sugar spikes).
What are low-GI foods?
Fruits, legumes, whole wheat products (cause gradual blood sugar rise)
Why are low-GI foods recommended for diabetics?
They help stabilize long-term blood glucose levels.
What are the effects of high sugar intake?
Obesity, type 2 diabetes, dental cavities, heart disease.
What is protein?
A macronutrient composed of amino acids, essential for growth, repair, and enzymatic functions.
What are the two types of amino acids?
Essential (must be obtained from diet) and non-essential (synthesized by the body).
Give examples of essential amino acids.
Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine.
What are complete proteins?
Proteins containing all essential amino acids, found in meat, fish, eggs, dairy, and soy.
What are incomplete proteins?
Proteins lacking some essential amino acids, found in plant-based foods like beans, lentils, and cereals.
How can vegetarians meet protein needs?
By combining different plant-based proteins (e.g., beans and rice).
What are the health effects of protein deficiency?
Muscle wasting, impaired growth, weakened immune function (e.g., kwashiorkor, marasmus).
What are the risks of excessive protein intake?
Kidney strain, osteoporosis, increased cardiovascular risk (from animal proteins).
How are proteins digested?
Broken down into amino acids by enzymes like pepsin, trypsin, and chymotrypsin.
How are amino acids absorbed?
Transported into intestinal cells and used for protein synthesis or energy.
What are lipids?
A group of hydrophobic molecules, including fats, oils, and steroids
What are the three main types of lipids?
Triglycerides, phospholipids, and sterols (cholesterol).
What is the main function of triglycerides?
Energy storage and insulation.
What is the role of phospholipids?
They form cell membranes and act as emulsifiers.
What is cholesterol used for?
Hormone synthesis, cell membrane structure, and vitamin D production.
What are the three types of fatty acids?
Saturated, monounsaturated, and polyunsaturated.
What are saturated fats?
Fats with no double bonds, solid at room temperature, found in animal products
What are unsaturated fats?
Fats with one or more double bonds, liquid at room temperature, found in plants and fish.
What are essential fatty acids?
Omega-3 (linolenic acid) and omega-6 (linoleic acid), which must be obtained from diet.
What are trans fats?
Artificially hydrogenated fats that increase LDL (bad cholesterol) and heart disease risk.
How are lipids digested?
Emulsified by bile salts, then broken down by pancreatic lipases.
What is the role of bile in fat digestion?
It emulsifies fats, allowing enzymes to break them down more effectively.
How are lipids absorbed?
Long-chain fatty acids form micelles, which enter intestinal cells and are packaged into chylomicrons for transport.
What happens to absorbed lipids?
Stored in adipose tissue or used for energy.
What are the health risks of high-fat diets?
Obesity, heart disease, stroke, high cholesterol.
What are the health risks of fat deficiency?
Impaired brain function, hormonal imbalances, dry skin, fatigue.
