Lecture 6: Protein Flashcards
What are examples of sources of protein among NZ adults (in order from highest to lowest)?
- Bread (11%)
- Poultry (9%)
- Milk (9%)
- Beef and veal (8%)
- Grains and pasta (7%)
- Bread-based dishes (7%)
- Fish and seafood (6%)
- Pork (5%)
What is the chemical structure of a protein?
They are amino acids linked together by peptide bonds
How much energy does protein give?
16.7 kJ/g
Explain the difference between non-essential and essential amino acids and how this relates to protein from animals vs plants
The body can create non-essential amino acids out of other things, whereas essential amino acids have to be consumed through food.
Amino acids from animal cells (eg. meats, poultry, fish, eggs, dairy) are “complete” sources of protein –> they contain all nine essential amino acids.
Amino acids from plant foods can vary in ‘completeness’ (how many of the nine essential amino acids they contain and in what quantities).
What is the average meat consumption per day for a person of 85kg and is this okay?
230g of meat per day, this is high and can be problematic for both health and environmental reasons
What are the dietary requirements for protein?
- Acceptable Macronutrient Distribution Range (AMDR): 15-25% of total energy per day
-
RDIs Adult women - 46 g or 0.75 g/kg (70kg woman =
53g/day) - Adult men - 64 g or 0.85 g/kg (80kg man = 68g/day)
- During periods of growth, pregnancy, and lactation protein
needs are higher - Children have high needs
How is the protein consumption among NZ adults?
People are meeting the AMDR reccommendations in every age group for both men and women, although just barely
Explain Protein Energy Undernutrition (PEU)
- Serious cause of ill health and death amongst young children in developing countries
- Severe inadequate energy or protein intake results in kwashiorkor or marasmus
- Not enough food implies not enough protein (most foods have some protein)
- Scale from mild to moderate
- PEU causes children to grow up smaller than genetic potential and be susceptible to gastroenteritis and respiratory infections as protein has a key role in immunity
- Older adults also susceptible
Explain stunting
= Child stunting refers to a child who is too short for his or her age and is the result of chronic or recurrent malnutrition. Stunting is a contributing risk factor to child mortality and is also a marker of inequalities in human development.
Explain wasting
= refers to a child who is too thin for his or her height and is the result of recent rapid weight loss or the failure to gain weight
Explain nutritional marasmus
- Starvation in an infant or young child, most commonly 6-18 months
- Child is very thin with marked wasting
- Diluted cereal drinks which do not have enough energy or protein
Explain kwashiorkor
- More common in children around 18 months to 2 years
- Common in countries where staple diets for weaned children have low protein/energy ratios (cassava, plantains, sweet potato or refined maize)
- Child is not necessarily underweight
- Child develops pot belly, oedema, changes in the skin and hair pigmentation
Explain possible results of excess dietary protein
- No upper limit due to insufficient evidence, but suggested 25%
- High animal products; possibly low in beneficial components of vegetable protein sources
- Increased calcium, water losses in some studies
- Extra load on kidneys
What are health benefits related to vegetarianism?
- Vegetarians often leaner
- Lower blood cholesterol
- Lower blood pressure
- Lower rates of heart disease
Which groups of people are more likely to be vegetarian?
- Women
- Asian people
- People with tertiary education
- Physically active people
What are 8 nutrients to pay extra attention to for vegetarians (/vegans)
- Completeness of protein intake; many legumes low in methionine (essential amino acid)
- Iron (poultry, meat)
- Zinc (fish, poultry, meat)
- B12 (eggs, dairy, fish, poultry)
- Vitamin D (fatty fish, cheese, eggs)
- Iodine (meat, poultry, eggs, dairy)
- Calcium (dairy)
- Riboflavin (dairy, eggs, meat, milk)
What two factors influence protein quality and how?
- Digestibility: proteins must be digested before they can provide amino acids; digestibility depends on the source and other foods eaten with it –> protein from animal products is more digestible
- Amino acid composition: if an essential amino acid is missing, a cell had to dismantle its own protein to obtain it; therefore to prevent protein breakdown, diet must contain all essential amino acids
Explain reference protein
= The quality of a food protein is determined by comparing its amino acid composition with the essential amino acid requirements of preschool-age children, this standard is called the reference protein
