Evaluating Nutrition information and macronutrients Flashcards
What is food made up of?
- Macronutrients and alcohol (energy yielding nutrients and alcohol) 2. Micronutrients (vitamins and mineral) 3. Phytochemicals (Secondary plant metabolites -phenolic acids, flavonoids in particular carotenoids and photos ternies) 4. Water( main component of body fluids) 5. Other (preservatives, colours)
Which Components of Food Provide ‘Energy’?
- Carbohydrates, fats and proteins are the only nutrients in foods that provide energy. Alcohol also provides energy
- These nutrients are also referred to as macronutrients and can be digested and metabolised by the body into fuel that our body uses to support physical activity and basic functioning.
- Alcohol in beverages will also provide energy/fuel for the body, however, it is not a nutrient (it is classified as a narcotic drug) because it does not support body functions.
- Although vitamins, mineral and other compounds in food are beneficial to the body in many other ways they will not provide you with the energy.
What are carbohydrates?
- Most important source of food energy in the world
- Carbs provide 17kJ/gram
- Plants make carbs from sunlight
- We eat plants and use this energy stored in the plants
- Largest single source of energy in diet
- Carbs necessary for brain function
- Many unrefined carbs provide fibre • What are the food sources of carbs???
What are carbohydrates?
Carbohydrates are chains of molecules found in three forms:
How are carbohydrates digested?
- Begins in the mouth with salivary amylase
- Primary site of CHO digestion is small intestine where enzymes amylase, sucrase and lactase cleave disaccharides into single sugars
- Monosaccharides absorbed into bloodstream via wall of small intestine
What is dietary fibre?
- Indigestible forms of carbohydrate - not broken down to glucose.
- Fibre uses intestinal bacteria to produce energy (8kJ/g)
- Two types: soluble & insoluble
Where is insoluble fibre found?
Leaves, roots, bran, whole grains and beans
Seed coverings (bran, wholegrains)
Plant stems, leaves and skin
How is insoluble fibre digested and what is its function?
Does no dissolve in water
Absorbs water through the colon bulk up stools and aids defamation
Helps to keep you regular
Where is soluble fibre found?
Fruits
Oats and barley
Beans, cereals, seeds, seaweed, psyllium
Inulin, gums
How are soluble fibres digested and what is its function?
- dissolves in water- gel-like
- resistant to digestive enzymes
- Fermented by bacteria in the colon to form acids that provide energy (8kj/g)
- Reduces blood cholesterol by binding to bile acids
What is polydextrose?
• man-made substance similar to soluble fibre, Iso fermented by bacteria (4kJ/g), not sweet, used as a bulking agent in carbohydrate modified products
What is resistant starch?
naturally occurring (e.g unripe bananas) and in commercial foods, resistant to digestion in small intestine, fermented by bacteria in colon, linked with positive gut health – area of research for microbiota and health
What is glycemic index?
- Ranks carbs on measured rise in blood glucose levels compared to a reference - Low: 0-55, Moderate: 56-69, High: 70 or more
- Limitations: complex, not consistent in categories, for carbs only
How much of our energy intake should come from carbohydrates?
45-65% total carbohydrate
15-25% protein
20-35% total fat
Carbohydrates
basic facts
What is protein?
A unique macronutrient as contains nitrogen
- Dietary protein provide amino acids for body to make proteins.
- Human body makes an estimated 10,000-50,000+ unique proteins from 20 aa’s
• Many cells and structures in the body being broken down and rebuilt and
require a steady supply of protein
• Proteins functions include:
– growth and development
– building and repair of muscles, bones, organs, blood, skin, hair
– repair of damaged tissues due to illness or injury
– regulation of body fluids and hormones
– blood clotting Body Dietary
– helping the immune system fight disease protein
How much of our energy intake should come from protein
15-25% protein
Protein
basic facts
What are lipids?
• Lipids are insoluble in water
• Many different forms in food and in the body. Three types
commonly found in foods and in cells and tissues of the body are:
– Triglycerides
– Phospholipids
–Sterols
• Triglyceride are most common food based lipid. Named because it has a glycerol head with 3 fatty acid chains
• Fats in our food = Triglycerides with combinations of different fatty acids. Triglycerides can be classified by their chain length, level of saturation , location of double bonds and isomeric form.
What is the fats classification by carbon chain length?
- Short-chain fatty acid (less than 6 carbons)
- Medium-chain Fatty Acid (6-12 carbons)
- Long-chain Fatty Acid (12 or more carbons)
Fats classification by saturation
- Saturated
- Unsaturated
What are the essential fatty acids?
omega-3 and omega-6
Which type of fat is not recommended
Trans fats
Describe the broad classification of dietary lipids
Refer to image
What is the process of lipid digestion?
- Begins in small intestine with emulsification by bile salts.
- Lipase acts in small intestine
- Monoglycerides cross the intestinal lining into bloodstream – resynthesized into triglycerides and transported as chylomicrons
How much dietary fat do we need in our diet?
20-35% total fat
Fats:
Basic facts
What health effects do different fats have? Is saturated fat healthy now?
Its complex but no!
• ↓ saturated fat and replace with unsaturated (not trans) →↓ CVD – (Cochrane review, ↓ saturated fat → 17% ↓ in CVD when replaced with
polyunsaturated fats. The greater the decrease in saturated fat the more serum cholesterol is reduced. Benefits healthy and high risk people; men and women)
• ↓ saturated fat and replace with wholegrains →↓ CVD (but not as much) • ↓ saturated fat and replace refined carbohydrates does not ↓ CVD • Trans fats are consistently linked to CVD • Unsaturated fat is preferred to saturated fat • ? Optimal amount of omega-3 and omega 6 fatty acids
