Section 1 The principles and key guidelines of nutrition Flashcards
Diet:
The current food intake and habits for any individual.
Healthy eating:
Food intake that promotes correct and optimal operation of the structures and systems of the body.
Balanced diet:
Eating foods of different types in amounts and levels that keep the body operating close to optimal level.
Nutrient groups
Macronutrients:
- Carbohydrates.
- Proteins.
- Fats (lipids).
Micronutrients:
- Vitamins.
- Minerals.
Peptide
Two or more amino acids joined together by peptide bonds.
Proteins
Peptides No. of amino acids Prefix
Dipeptide 2 amino acids Di = 2
Tripeptide 3 amino acids Tri = 3
Oligopeptide 4-9 amino acids Oligo = few
Polypeptide 10+ amino acids Poly = many
Amino acids
The building blocks of proteins.
Amino acids
Essential Non-essential Conditional
Histidine Alanine Arginine
Isoleucine Asparagine Cysteine
Leucine Aspartic acid Glutamine
Lysine Glutamic acid Glycine
Methionine Proline
Phenylalanine Serine
Threonine Tyrosine
Tryptophan
Valine
Catabolism and anabolism
Catabolism: processes by which substances are broken down into simpler molecules, releasing energy.
Anabolism: energy-requiring reaction in which simpler molecules are combined to form more complex substances.
Anabolism = to build up
Catabolism = to break down
Protein requirements
Daily protein requirements (grams of protein per kilogram body mass)
Sedentary adult 0.8
Recreational adult exerciser 0.8-1.5
Adult endurance athlete 1.2-1.6
Growing teenage athlete 1.5-2.0
Adult building muscle mass 1.5-1.7
Estimated upper adult limit 2.0
Carbohydrates
All carbohydrates are made up of molecules or units called saccharides.
There are three basic categories:
- Simple carbohydrates – ‘sugar’.
- Complex carbohydrates – ‘starches’.
- Non-starch polysaccharides (NSP) – ‘fibre’.
Dietary carbohydrate
- Ultimately sent to the liver, muscles or used immediately as a fuel.
- Glucose may enter the adipose tissue (fat tissue) to help store fat.
- Carbohydrates and fats contribute significantly to energy requirements.
Simple carbohydrates
Fruit (healthy choice)
- Contains fructose and glucose in varying amounts
- Contains vitamins and minerals
- Contains antioxidants and phytochemicals
- Contains high levels of dietary fibre
- Contains traces of amino acids
- Cheap and convenient
Biscuits, cake, confectionary, soft drinks (less healthy)
- Contain excessive sugar - higher than 15g per 100g
- Contain processed, low quality fats
- High energy density
- Contain no vitamins or minerals
- Adversely affect insulin response
Complex carbohydrates
Refined carbohydrate
- White bread
- White pasta and rice
- Cakes, biscuits, pastries
- Rice cakes
Properties
- Contain excessive sugar; over 15g per 100g
- Contain processed, low quality fats
- High energy density
- No vitamins and minerals
- Adversely affects insulin response
Unrefined carbohydrate
- Wholemeal or whole grain products
- Quinoa
- Frozen/fresh vegetables
- Pulses
Properties
- Contain fructose and glucose in varying amounts
- Contain antioxidants and phytochemicals
- High levels of dietary fibre
- Contain vitamins and minerals
- Contain trace of amino acids
Fibre
Insoluble fibre:
- Found in the outer protective layer of plants.
- Unrefined wheat, bran, rye, rice and most other grains.
Soluble fibre:
- Found in the inner part of plants.
- Barley, broccoli, prunes, apples, citrus fruits and oats.
Fats (lipids)
Oils: lipids that are liquid at room temperature.
Fats: lipids that are solid at room temperature.
Classification and function of fats
Key physiological functions of lipids:
- Formation of virtually all cell membranes.
- Formation of myelin sheath within nervous system.
- Constitutes majority of CNS and spinal cord.
- Synthesis of steroid hormones.
- Assists in the regulation of enzymes.
- Insulation through subcutaneous adipose tissue.
- Protection of internal organs.
- Transportation, storage and utilisation of fat soluble vitamins A, D, E, K.
- Fuel source during lower intensity workloads.
- Storage of energy within the adipose tissue.
Lipids
A group of organic molecules, most of which do not dissolve in water.
Fatty acids
- Monounsaturated.
- Polyunsaturated.
- Saturated.
Fatty acid:
an organic molecule made up of a chain of carbons linked to hydrogens with an acid group at one end.
Despite long-standing assertions to the contrary, the brain can use fatty acids as a source of fuel.
Triglycerides
The major form of lipid in food and in the body is known as a triglyceride.
It consists of three fatty acids attached to a glycerol molecule.
Saturated fat
Animal sources: meat (beef, pork, lamb, venison), poultry (chicken, duck), dairy (milk, cheese yoghurt, cream, butter), eggs.
Non-animal sources: palm oil, coconut oil.
Unsaturated oil
Monounsaturated: a single double bond – single bend in molecule.
Polyunsaturated: several double bonds – several bends in molecule.
Monounsaturated fatty acids
Sources of monounsaturated fatty acids:
- Olives/olive oil.
- Lard.
- Beef dripping.
- Peanut oil.
- Rapeseed oil.
- Avocado.
- Nuts.
- Seeds.
Polyunsaturated fatty acids
Omega-3 fatty acids: oily fish, flax oil, walnuts, pasture-reared eggs.
Omega-6 fatty acids: sunflower seeds, sunflower oil, safflower oil, pumpkin seeds, sesame seeds.
Note: all oils need to be cold pressed and remain unprocessed.
Hydrogenated fats
Hydrogenated fats (saturated fats) are unnatural fats that are detrimental to your health.
- Margarine.
- Vegetable shortening.
- Packaged snacks.
- Baked foods, especially premade versions.
- Ready-to-use dough.
- Fried foods.
- Coffee creamers, both dairy and non-dairy.
Cholesterol
Dietary cholesterol intake low – body increases the synthesis of its own supply.
Dietary cholesterol intake increases – cholesterol production falls.
Lipoproteins completely encase lipids for transport in the blood.
Functions of cholesterol
Very low density lipoproteins (VLDL): synthesised by the liver, contain cholesterol and triglycerides, transport triglycerides into adipose tissue.
Low density lipoproteins (LDL): formed from VLDLs once they have unloaded most of their triglycerides, transport the remaining cholesterol to cells throughout the body that are in need.
High density lipoproteins (HDL): synthesised by the liver, transport excess cholesterol from the tissues and blood back to the liver.
Micronutrients – vitamins
Fat-soluble vitamins:
- A
- D
- E
- K
Water-soluble vitamins:
- B
- C
Micronutrients – minerals
- Build strong bones and teeth.
- Control body fluids inside and outside cells.
- Turn food into energy.
Antioxidants
Sources of antioxidant nutrients:
- Vitamin C – citrus fruits, green vegetables, peppers, tomatoes, potatoes.
- Vitamin E – unrefined vegetable oils, egg yolks, whole grains, almonds, nuts, green leafy vegetables.
- Zinc – oysters, ginger root, lamb, nuts , grains, eggs, peas.
- Selenium – grains, meat, fish, brazil nuts, shellfish, dairy.
US national food and nutritional guidelines
UK national food guidelines
Healthy eating tips:
- Base your meals on starchy foods.
- Eat lots of fruit and vegetables (5 portions per day).
- Eat more fish (2 portions a week, 1 oily).
- Cut down on saturated fat and sugar.
- Try to eat less salt, no more than 6g a day.
- Get active and try to be a healthy weight.
- Drink plenty of water (6-8 glasses per day).
- Don’t skip breakfast.
National food model targets:
- Adult males: 2550 calories per day.
- Adult females: 1950 calories per day.
Traffic light system
- Red = high.
- Amber = medium.
- Green = low.
Food Standards Agency (FSA)
Food production, labelling, and manufacture are governed by the 1990 Food Safety Act.
Food marketing terminology
- Fresh: ‘to differentiate food sold a short time after harvest.’
- Pure: ‘single ingredient foods…or to highlight the quality of ingredients of a food.’
- Natural: ‘comprised of natural ingredients, not the work of man.’
- Authentic: ‘remains unchanged…originates from the area implied by its name.’
- Homemade: ‘made in the home, or of domestic manufacture.’
- Traditional: ‘a method of preparation that has existed for a significant period.’
- Farmhouse: ‘other than bread, it should refer to food produced on a farm.’
- Original: ‘a method of preparation that has remained essentially unchanged over time.’
Healthy marketing terminology
- ‘Light, low, reduced or high’: there are no specific guidelines for these terms, but they should not mislead.
- ‘Reduced or low fat’: this must be at least 25% lower in fat, but often calories are maintained by adding other ingredients.
- ‘Low calorie’: this must have lower calories than the original, but there is no set level.
- ‘Sugar free’: sugar has not been added, but almost always an artificial sweetener has been used for taste.
Refined sugars and sweeteners
Commonly added sugars and caloric sweeteners:
- Dextrose.
- Glucose syrup.
- Inverted sugar syrup.
- High fructose corn starch.
- Mannitol.
- Xylitol.
- Sorbitol.
- Maltodextrin.
Artificial sweeteners:
- Aspartame.
- Sucralose.
- Acesulfame.
- Saccharin.
