Nutrition and Energy (Key Components of Diet) Flashcards
What are the three macronutrients?
Carbohydrates, Proteins and Fats
How many calories of energy do carbohydrates. proteins and fats yield per gram?
Carbohydrates = 4kcal Proteins = 4kcal Fats = 9kcal
What is the main source of fuel for the body?
Carbohydrates/glucose
When digested, carbohydrates are broken into what?
Glucose
Where can carbohydrates be found?
Grains, fruits, dairy, vegetables, potatoes and legumes
What percentage of our daily energy intake should come from carbohydrates?
45-65%
What are three main monosaccharides?
Glucose, Fructose and Galactose (All of which are isomers of each other)
Which monosaccharide is present in all three main disaccharides?
Glucose
What are the three main disaccharides?
Maltose, Lactose and Sucrose
Which monosaccharides are maltose molecules made up of? Where does it normally occur?
2 glucose molecules. It occurs in starch breakdown and alcohol fermentation
Which monosaccharides are lactose molecules made of? Where is it mainly found?
Glucose and galactose. It is the main carbohydrate found in milk
Which monosaccharides are sucrose molecules made of? What is sucrose commonly known as?
Fructose and glucose. It’s commonly known as table sugar and is the natural sweetness in fruit, vegetables and grains
What are the two variations of starch polysaccharides?
Amylose (unbranched with 1,4 glycosidic bonds) and amylopectin (branched 1,6 glycosidic bonds with main chain 1,4 glycosidic bonds)
Is starch the main form of glucose storage for plants or animals?
Plants
What are good dietary sources of starch?
Wheat, rice, root crops, potatoes, kumara, lentils and beans
Can dietary fibre be digested and absorbed?
No
What are the two types of dietary fibre?
Soluble and insoluble
What happens when soluble fibre dissolves in water? What does this do to the passage of food through the gastrointestinal tract?
It becomes a viscous gel which slows the passage of food through the gastrointestinal tract, allowing more time for enzymes to act on it
Can soluble fibre be broken down (fermented) by gut bacteria (microbiota)?
Yes
Can insoluble fibre be broken down (fermented) by gut bacteria (microbiota)?
No
What is the importance of insoluble fibre in ensuring the healthy passage of food through the gastrointestinal tract?
It bulks up the stool and prevents constipation
Does resistant starch behave more similarly to soluble or insoluble fibre?
Soluble fibre
What uses resistant starch as food?
Gut bacteria (microbiota)
What are some sources of resistant starch?
Legumes, cooked then cooled potatoes/pasta, green bananas
Is glycogen the main form of glucose storage for plants or animals?
Animals
In terms of it’s use, what is the difference between glycogen breakdown in the liver versus in muscle?
The liver breaks down glycogen to release glucose into the bloodstream whereas muscles break down glycogen to provide energy for themselves
What basic unit are proteins made out of?
Amino acids
Can the body use proteins/amino acids as energy?
Yes, but only in dire situations when glucose is not readily available
How is the nutritional value of a source of protein measured?
By the quantity of amino acids present in the source (especially essential amino acids)
What are some dietary sources of proteins?
Legumes, fish, eggs, nuts, seeds, meat
What is the key difference between essential and non-essential amino acids?
Essential amino acids cannot be synthesised within the body so must be obtained through diet, whereas non-essential amino acids can be synthesised in the body (so long as all required materials are present)
What happens if any amino acids are absent within the body?
Protein synthesis will not occur
What is the difference between complete proteins and incomplete proteins?
Complete proteins contain all 9 essential amino acids whereas incomplete proteins lack at least one
What percentage of our daily energy intake should come from proteins?
15-25%
What does a positive nitrogen balance mean? What can result in this?
Protein synthesis is exceeding protein breakdown
Can be the result of: Increased protein intake (short term) Growth (infancy, childhood, adolescence) Pregnancy Recovery following illness Training (Gaining lean body mass)
What does a neutral nitrogen balance mean? What conditions should be met for this to occur?
Protein synthesis and breakdown must be occurring at equal rates, leading to body weight and lean body mass remaining constant in an active and healthy adult who’s protein needs are satisfied
What does a negative nitrogen balance mean? What can result in this?
Protein breakdown exceeds protein synthesis
Can be the result of: Starvation (Decreased protein intake) Reduced gastrointestinal function Stress (burns, injury, infection, fever, surgery, post op complications) Cancers Lactation
What percentage of our daily energy intake should come from fats?
20-35%
Other than being used for energy, what is fat used for?
Cell, nerve tissue and hormone production and absorption of fat-soluble vitamins (A, D, E, K and carotenoids) among other functions
What is the main structural difference between saturated and unsaturated fats?
Saturated fats only have single bonds linking the carbon chain together, resulting in a straight chain whereas unsaturated fats contain at least one double bond, resulting in a bent carbon chain
How do the structural differences between saturated and unsaturated fats affect their states at room temperature?
The straight chains of saturated fats allow tighter packing together of molecules, resulting in them being rigid at room temperature, whereas the bent chains of unsaturated fast don’t allow such close packing, resulting in them being liquid at room temperature
Why should saturated fat intake be minimised? How much should saturated fat contribute to our daily energy intake?
It has been linked to cardiovascular disease. It should contribute to less than 10% of daily energy intake
What are some dietary sources of saturated fats?
Animal fats, butter, coconut oil
What are some dietary sources of unsaturated fats?
Plant and seed oils, cold water fish (e.g. salmon, mackerel), avocado, canola oil
What are the non-energy yielding nutrients (Micronutrients)?
Vitamins, Minerals, Water and Fibre
What are vitamins?
Organic molecules that facilitate the release of energy from carbs, proteins and fats
What are minerals?
Inorganic substances that can be found in substances that interfere with absorption
What are some of the roles water plays a part in within the body?
Metabolic reactions, cell mediums, acid/base balance, waste removal
What are the four sources of the body’s energy requirements?
Basal metabolic rate:
Amount of energy to stay alive (Breathing, circulation, body temperature, cell repair)
70% of energy requirement
Thermic effect of food:
Energy required to eat, digest and store nutrients
Exercise
Non-exercise activity thermogenesis: Existing
