Proteins & Amino Acids Flashcards
Why is insufficient protein in the blood problematic?
- Lack of protein decreases fluid return to capillary due to low oncotic pressure
- Results in edema
What are essential amino acids?
- Need to taken in through diet because body cannot make them
- Some are also conditionally essential, they may need a precursor to be made or perhaps children need more of them`
How are proteins related to allergies?
- Protein may be absorbed intact
- First time, immune system is stimulated
- Consumption again causes recognition as a foreign substance
- An immune response is mounted and an allergic reaction occurs
- This response may be life-threatening if anaphylaxis occurs and there are breathing difficulties or a huge drop in BP
What are recent studies finding about infants and peanut consumption?
- Early introduction of peanuts significantly decreased the frequency of developing a peanut allergy
- Immune system is less mature and less likely to react adversely
What is the structure of proteins?
- Involves an amino group with a side chain, and a carboxylic acid group
- Amino group contains nitrogen
- Structure directed by DNA
- Form polypeptides with other amino acids
- Improper protein synthesis can result in altered polypeptide shape (ex. sickle cell anemia)
What are “limiting amino acids”?
- A shortage of an amino acid limits the ability to synthesize a protein that is high in this amino acid
- Needs to be accessible from the amino acid pool
- All protein is functional, cannot be stored
What are proteins in the amino acid pool used for?
- Energy production
- Synthesis of glucose or fatty acids
- Synthesis of nonprotein molecules containing nitrogen (ex. NTs and DNA)
What is negative and positive nitrogen balance?
- Nitrogen intake does not equal nitrogen output
- Negative: nitrogen intake < nitrogen output, so total body protein decreases as when someone is ill
- Positive: nitrogen intake > nitrogen output, so total body protein increases, as during pregnancy or growth
What are sources of dietary protein?
- Meats, fish, eggs and dairy products - main sources of animal proteins
- Plant sources of protein - legumes, vegetables and grains
- The source of protein will determine what other nutrients are consumed with it
What is the primary source of protein for most of the world’s population?
- Grains and vegetables
Plant sources of protein tend to be less ____.
Expensive
What is protein complementation?
- Says meat contains all the amino acids we need
- Most plants, other than soy, supply incomplete proteins
- Need to choose plants containing complementary amino acids to provide all essential AAs (ex. rice and beans)
- No evidence to support this, no need for complementation for vegetarians/vegans
Are there differences in protein quality among different sources?
- Isolated soy protein and egg white easily digestible and accessible protein
- Many plant proteins are harder to access
What is the association of animal and plant protein intake with mortality?
- High animal protein intake was positively associated with mortality and high plant protein intake was inversely associated
What time of day is it best to consume protein?
Protein consumption should be evenly distributed over three meals, as it is associated with greater muscle strength
