FEB 7

7. FEB 7

Nix, Stacy. Chapter 4: "Proteins" Williams' Basic Nutrition and Diet Therapy (pp. 47-63).
Fill out Proteins Worksheet (Points)

20 amino acids, 9 essential; proteins are polypeptides -- chains of amino acids 100s of links long. Proteins exist in specific forms in foods (ex. casein is milk protein) and are broken down by us into amino acids and resembled as protein in metabolism.
Classes of amino acids: indispensable (9), dispensable (5), and conditionally indispensable (6).
Conditionally dispensable: Example: If low on Mthionine(essential), then you need cysteine (cond. indis.) from diet.
About 16% nitrogen; protein is a primary source of nitrogen in diet.
Catabolism and Anabolism: Metabolic process of breaking down tissue and building it up.
Nitrogen Balance is shown when excretion of urinary nitrogen occurs as by product of protein metabolism (ratio of 1 g of urinary nitrogen to 6.25 g of protein). Negative nitrogen balance can be a symptom of protein deficiency. Kwashiorkor.
Tissue proteins, plasma proteins, and dietary protein. You dietary protein is contributing to a much larger and complex protein manufacture and delivery service.

Tissue growth/repair: largest component of tissue by dry weight. 75% of dry body weight.
Water and pH balance; plasma proteins can exert osmotic pressure to help circulation of tissue fluids (I think this is the "interstitium", but I'm not completely sure).[1] [2]
Proteins can take up acids to contribute to blood Ph management.
Metabolism, transport, immune system, energy system. Wide range of functions here. We have already met "lipproteins" that help carry fats around. Here you learn that enzymes, transport agents, and hormones also have protein structures.
Proteins also help make white blood cells, so support your immune system.

Complete proteins mostly from animal sources, including dairy, cheese.
Soy is the only complete plant protein.
Completing proteins, or, more current “protein scores”: p. 52. also compare links ceci beans [[3]], lentils [4], peanut butter [5] and sesame seeds [[6]]. Sirloin steak [7]. Note how you can use the site to find complementary foods for foods with relatively low amino acid scores.
advice on vegetarian diets - Mix grains and legumes, eat soy based foods like tofu if possible. Note reference to the Academy of Nutrition and Dietetics document (in your links collection) — No long need to balance plant protein within each meal. (old advice). With variety of plant protein sources, you can do fine. Note health benefits of vegetarian diet on p. 54.

Occurs in stomach and small intestines - unlike Carbs and Fats, which are not digested in stomach.
Proteing enzymes have to be stored in inactive form (proenzymes or “precursors”) or they would break down body tisssue!

10-35% of calories from diet
.8g / Kg of body weight.
Overconsumption of protein by Americans, p. 59 Men at 181% of DRI, Women at 152%.
[Blood test for protein sufficiency: Prealbumin test [8]
Reasons not to consume excess amounts of proteins:

We've used a "profile" metaphor to talk about carbs and fats (profiles of complexity in carbs and fat saturation for fats), but with proteins, it makes sense to "tally" or add up your intake, while watching for protein quality.

Calculate your protein goal in grams. 150 lbs. = 68kg x .8 = 54grams RDI /day
Go through your diet and look at the amounts of good protein in your day. How hard is it to meet your goal?