Chapter 6 Flashcards
Sources of Dietary Protein in Canada
97% eat more than AMDR
Meat, poultry, fish, eggs, dairy provide 62% of protein; plant proteins are emphasized in the new Canada Food Guide. (legumes, nuts/seeds, grains
17% follow diet that restricts meat partially/completely
Average intake 15% of kcals
Nutrients provided by plant proteins
Lower in fat, high in fiber, antioxidants, but sometimes incomplete in amino acid profile (e.g., lacking one or more essential amino acids)
Nutrients provided by animal proteins
High in essential amino acids, vitamin B12, iron, and other nutrients, but can be higher in fat.
Amino Acids
Building blocks of proteins. Peptide bonds link amino acids to form polypeptides, which fold into a three-dimensional structure.
Consists of a Carboxyl group, Amino Group, Central Carbon
Protein Shape
The shape determines the function (e.g., collagen and elongated are connective tissue proteins, spherical shape is hemoglobin). Misfolding can lead to diseases like sickle cell anemia, where abnormal hemoglobin shape affects oxygen transport
Sickle cell anemia
Shows the importance of protein shape in function, where a small mutation leads to severe health complications.
Altered polypeptide shape -> Altered Hemoglobin Shape -> Long chains of molecules in hemoglobin arrangement -> Red blood cells shape is Sickle-shaped
Essential Amino Acids
Must be obtained from the diet. Cannot be synthesized by human body in sufficient amounts to meet needs
Non-Essential Amino Acids
Can be synthesized by the body.
Conditionally Essential Amino Acids
Required during certain conditions like illness or stress. Essential under certain conditions
Transamination
When a nonessential amino acid is not available from the diet, it can be made in the body by the process of transamination.
Protein Digestion
Proteins are broken down into amino acids in the stomach and small intestine
breakdown of proteins into amino acids and peptides
Food Allergies
occur when undigested proteins are absorbed into the bloodstream, triggering immune responses
Protein absorption
The process by which amino acids, dipeptides, and tripeptides are transported from the small intestine into the bloodstream to be used by the body.
uptake of these smaller components into the bloodstream for use by the body.
Amino Acid Pool
collection of free amino acids available in the body at any given time. These amino acids come from various sources, all over the body so they are readily available for immediate use.
including Dietary proteins, Body proteins and Non-essential amino acids
Amino acid availability
access the body has to amino acids in the pool to meet various physiological needs. These include: Protein Synthesis, Energy Production, and Synthesis of non-protein compounds
If amino acids are missing, the body must break down its own proteins to supply the missing amino acids
Pescetarians
exclude all animal flesh except for fish
Semi-vegetarians
avoid certain types of red meat, fish, or poultry
Lacto vegetarians
eat dairy products but no animal flesh nor eggs
Lacto-ovo vegetarians
eat no animal flesh but do eat eggs and dairy
Vegan
eliminates all animal products
Protein complementation with vegetarians
Combining plant foods (e.g., rice and beans) to ensure all essential amino acids are consumed.
nutrients of concern with vegetarians
Plant proteins (e.g., legumes, grains, nuts, seeds) are often incomplete, meaning they lack one or more essential amino acids.
Examples of Protein Complementation
(Rice and Beans)
Rice is low in lysine but high in methionine, while beans are high in lysine but low in methionine. Together, they provide a complete protein.
Soy Benefits
Soy Products are Rich in high-quality protein and contain isoflavones that may reduce heart disease risk, help with menopause symptoms, and improve bone health
Protein Synthesis
Involves Transcription and Translation
Transcription
DNA to mRNA
Translation
mRNA to Protein
Proteins for energy
When energy is low, amino acids can be used for gluconeogenesis or energy production through deamination and transamination
Deamination
removes the amino group for energy use ((NH₂), turning it into ammonia)
carbon skeleton can then be used for energy or to make glucose or fat, depending on the body’s needs.
Transamination
transfers the amino group to create new amino acids. (keto acid)
Protein Deficiency
protein deficiency conditions that may include only protein deficiency or protein deficiency plus
energy deficiency.
❑ Leads to conditions like marasmus and Kwashiorkor
Marasmus
(energy deficiency)
Fat stores have been utilized. No bloating in belly (energy deficiency)
Kwashiorkor
(pure protein deficiency)
Fat stores retained. BLOATED
High Protein Diets
Can strain the kidneys, contribute to dehydration, bone health concerns and potentially increase the risk of heart disease and cancer
(saturated fat increase -> animals and Lack of fibre)
General Protein Recommendations
0.8g/kg/d body weight AMDR 10-35% of total calories
Special Populations Protein Reccomendations
Higher needs for pregnant or lactating women, children, athletes (1.2-1.7g/kg/d), and those under stress
Complete Proteins
Contain all essential amino acids (e.g., animal proteins, soy).
Incomplete Proteins
Lacking in one or more essential amino acids (e.g., some plant proteins).
Nitrogen Balance
Reflects protein status
neutral in healthy adults,
positive during growth (pregnancy)
negative during illness or malnutrition
