Macro-nutrients Flashcards
Nutrition
Science of foods and their actions within the body substance that is absorbed into the bloodstream from the diet
Diet
Selection of foods and
beverages that an individual
eats and drinks
Classes of diet
- Carbohydrates
- Protien
- lipids
- Mineral salts and water
What do macronutrients require
- Water
- Carbs
- Protiens
- Fats
Requires in large amounts
Micronutients
- Vitamins and minerals
body require in small ammounts
Energy yeilding nutrients
- Organic nutrients that are broken down to provide energy
- Carbs and protien release 4g of energy fats 9g
Daily calorie intake
Energy intake from food that replaces energy
expenditure needed for all daily functions
Low calorie intake
- Weight loss with nutrient deficiency
High calorie intake
- Weight gain and chronic disease
Monosaccharides
- Smallest sugar unit (CH2O)n
Disaccharides
- Two linked monosaccaride units
Polysaccharides
- Few and
thousands of monosaccharides linked together e.g. chitin, glycogen and starch
Glucose
- Enter cell via active transport releases immediate energy
- Excess stored in glycogen via liver and muscle cells
- Blood glucose regulation
Sucrose
- Glucose and fructose
Lactose
- Galactose and glucose
Maltose
- 2 glucose units
Glycogen
- Multibranched polysaccharide in meats
- Storage from glucose in heptic and skeletal cells
Starch
- Long branched or unbranched glucose
- Grains, ric eand wheat
- Salivary and pancreatic amylases into
disaccharides then maltose to glucose
Dietary fibres
Composed of a variety of distinct monosaccharides
Digestion of dietry fibres
Large intestine, where some are broken down by bacteriaTrap/get rid of bile cholesterol levels decreases
What does low fibre cause
- Constipation and haemorrhoids
- Increased risk of heart diseases and some types of tumours
Glycaemic Index
Food increases blood sugars and elicit insulin response
High GI
Raise blood sugar high and rapidly
Low GI
Rise blood sugar slowly and to a lesser extent
Type 2 diabetes and low GI foods
Help stabilise long-term blood glucose levels
High fat low GI foods
- Decrease in carb absorbtion
Hypoglycaemia
- Sugar deficiency causing dizziness
High sugar intake causes
- Obesity and wight gain and chronic diseases with dental caries
Non-essential amino acids
- Amino acids synthesised in the body
Essential amino acids
- CANNOT be synthesised by the body
▪ MUST be provided in the diet
Conditionally Essential Amino Acid
- Non-essential become essential for newborns
Complete proteins
- Containing all the essential amino acids in the required proportions
- meat, fish, soya beans, milk, and eggs
Incomplete protiens
- Not containg all the essential amino acids in the correct proportions.
- Mainly of vegetable origin (cereals, peas, beans, and lentils).
- A diet based on a wide variety of incomplete proteins can avoid amino acid deficiencies for vegetarian or vegan diets
Protein Deficiency
- Too little protein or lacks essential amino acids, Marasmus and kwashiorkor
- Weight loss slowed growth and eating disorder
Excess of Proteins
- Cardiovascular diseases
- Cancer (processed & red meat as carcinogens),
- Osteoporosis - calcium excretion increases, depleting the bone
- Kidney stones - Excess of Proteins
Protien digestion
- Pepsin and acid act on the protien forms shorter polypeptides
- Pancreas and small intestine secreate peptidase to form amino acids
Amino acid absorption
- Intestinal cells uptake amino acids and:
- released into the bloodstream
- used to make proteins
- converted to glucose, if needed
- broken down to provide energy via deamination producing
ammonia (NH3) that is then converted to ure
Lipids in nutrition
- Major fuel source during light/moderate exercise
- Major store of energy from food
- Primary component of cell membranes and nerve sheaths
- Thermal insulation for the organs
- Required for the synthesis of steroid hormones
Fatty acids such as triglycerides
- Glycerol backbone
- 3 fatty acid chains
Phospholipids
- Amphipathic molecule
- Head, phosphate and glycerol backbone with 2 fatty acid chains
Sterols
- Vitamins hormones and cell membranes
Fatty acids
Aliphatic building blocks of triglycerides, phospholipid and glycolipids
Degree of saturation
- Number of double bonds in the chain
Saturated fatty acid properties
- Solid at room temp which are more resistant and stable to oxidisation
- Animal based food causes risk factor of heart disease
Unsaturated fatty acids
- More unsaturated points has,
the more liquid - The more unsaturated points, the
less stable - Protective against chronic diseases
Unsaturated fatty acid properties
- More unsaturated more liquid at room temp
- Less stable to oxidation
- Plant based food and seafood
- Protective against chronic conditions
Example of essential fatty acids
- Linolenic acid omega 3 and 6
- Essential fatty acids must be provided by diet
Trans-fatty acids
- Hydrogenation of unsaturated fatty acids
- Partially hydrogenise food to extend shelf life some change configureation from cis to trans
- H opposes the double bond
Increase in trans fatty acids
- LDL cholesterol in blood therefore increases heart disease
Digestion of lipids
- Via the mouth lingual lipase via salivary glands
- Stomach gastric lipase
- Small intestine release cholecystokinin from gallbladder and bile emulsifies fat for digestion degrading triglyceride
Absorbtion of fatty acids
- Long chain fatty acids and monoglycerides combine with bile to form micelles diffuse and reassemble into triglycerides
- Triglycerides and phospholipids are packaged
with proteins as chylomicrons
Chylomicrons
- Transport vehicles
released into lymph vessels and reach the bloodstream
Where are triglycerides
- Stored in the adipose tissue
- In energy deficit, triglycerides are hydrolysed
to release energy
