Ch.7 Proteins

Is vegetarian a healthy lifestyle?

a. Lower risk of obesity b. Lower risk of type 2 diabetes c. Lower risk of hypertension d. Lower risk of certain cancers

Sickle cell anemia

a genetic disorder that causes abnormal hemoglobin, resulting in some red blood cells assuming an abnormal sickle shape -hemoglobin is unable to efficiently carry oxygen thru the blood and causes tissue damage or death

Usual suspects for food allergies

a. Cow's milk b. Eggs c. Peanuts and other nuts d. Wheat e. Soybeans f. Fish and shellfish g. Nonprotein food dyes or additives (e.g., sulfites)

Semivegetarian

avoids red meat but consumes other animal foods

Vegetarian

rely heavily on plant foods; may or may not include some animal foods

Peptide

short chain of amino acids -fewer than 15 amino acids in its structure

Excessive protein intake

1. High protein diets are generally not recommended. Although excess protein increases urinary excretion of calcium, scientists do not agree on whether the loss has a major effect on bone heath. 2. Protein-rich foods are sources of purines. Kidneys break down purines to form uric acid. a. High uric acid in the bloodstream may contribute to gout. b. High uric acid in urine may contribute to kidney stones. 3. Excess protein intake can lead to dehydration because kidneys require more water to dilute and excrete the metabolic byproducts of protein metabolism. a. People with liver or kidney diseases may need to limit protein intake.

Protein deficiency

1. In the United States, people with low-incomes, especially older adults, have high risk. 2. Protein undernutrition can develop in people with serious chronic diseases. a. Chronic inflammation affects cells' ability to use proteins. i. Chronic inflammation increases body's need for protein. b. Loss of appetite c. Inability to chew and/or swallow properly.

Marasmus (severe PEM)

a) Extreme weight loss due to lack of sufficient energy and protein. b) Weakness and wasting c) If not treated with a nutritious diet, death results.

What is celiac disease?

-allergic reaction to gluten, group of related proteins in wheat, buckwheat, barley, and rye may trigger an immune response in the small intestine that inflames and destroys villi

Amino Acids

-building blocks of protein -twenty difference amino acids are used to make proteins for the human body -chemical structure of an amino acid: a. carbon skeleton - central carbon anchor, R group, acid group b. amino (nitrogen-containing group)

Proteins in the body

-complex organic molecules containing carbon, hydrogen, oxygen, and nitrogen a. Development and maintenance of all body tissues b. Structural proteins (e.g., collagen, keratin) c. Contractile proteins d. Transport proteins e. Blood clotting proteins f. Lubricants g. Many hormones: chemical messengers that regulate body processes and responses h. Neurotransmitters: substances that send signals between nerve cells i. Enzymes: compounds that speed up chemical reactions j. Antibodies k. Source of energy (under usual conditions, to a limited extent) l. Maintenance of fluid balance i. Concentration of proteins in blood retains fluid in the blood ii. Low blood protein concentrations allow fluid to leak from blood into surrounding tissues, resulting in edema m. Maintenance of acid—base balance: in fluids, proteins act as buffers because they have both acidic and basic components that help keep the pH level within normal limits.

Negative nitrogen balance

-nitrogen losses exceed nitrogen retention; occurs during or in response to: a. Inadequate protein intake or inefficient protein absorption b. Certain kidney diseases or blood loss c. Bed rest d. Fever, injuries, burns e. Increased levels of thyroid hormone or cortisol

Protein denaturation

-occurs when exposed to certain environmental factors that alter the proteins shape/function 1. heat 2. alcohol 3. acid 4. mechanical disturbance (whipping)

Accurate diagnosis of food allergy

-should be taken by an immunologist: physician who specializes in the diagnosis and treatment of allergies a. Skin testing is a reliable way to identify allergens. b. Treatment of food allergies involves strict avoidance of the offending foods. c. Read labels carefully for allergen warnings and allergens listed among ingredients. d. Educate teachers and other adults associating with the allergic child about the importance of not exposing the child to specific foods.

Positive nitrogen balance

-the body retains more nitrogen than it loses as proteins are added to tissues. Occurs during or in response to: a. Growth b. Pregnancy c. Recovery from illness/injury d. Increased levels of insulin, testosterone, and growth hormone e. Resistance exercise

Protein turnover

1. Constant breakdown of old or unneeded proteins into their component amino acids to recycle them into new proteins 2. Endogenous amino acid pool: amino acids available in the body from protein turnover 3. Exogenous amino acids: those obtained from the diet

How the body synthesizes protiens

1. DNA in the cell's nucleus is a double helix structure. a. Within the cell's nucleus, a section of DNA's double helix unwinds to expose a gene (set of instructions for protein synthesis). b. Transcription: messenger ribonucleic acid (mRNA) takes the code from the gene out of the nucleus and into the cytoplasm to the ribosome. c. Translation: transfer RNA (tRNA) conveys amino acids to the ribosome, where they are assembled into a polypeptide, according to the gene's code. d. The polypeptide is released into the cytoplasm and undergoes further processing at other sites within the cell.

How much protein do you need?

1. EAR (Estimated Average Requirement): 0.66 g/kg body weight 2. EAR increases during pregnancy, breastfeeding, periods of rapid growth, and recovery from serious illnesses, blood losses, and burns. 3. RDA (Recommended Dietary Allowance) for a healthy adult is 0.8 g/kg of body weight.

What is a food allergy?

1. Food allergy is an inflammatory response resulting from an inappropriate immune reaction to a harmless substance (allergen) in a food. a. Occurs when proteins are not digested, but are absorbed intact by the small intestine. b. Immune cells recognize the intact protein as a foreign substance and mount an immune response, which can include hives, swollen lips, breathing difficulties, vomiting, and diarrhea. c. Allergic reactions usually occur within minutes to hours of eating the offending food. d. Some food allergies can be deadly if they result in anaphylactic shock, a dangerous drop in blood pressure. Anaphylaxis can be fatal. e. Genetics play a major role in the risk of food allergies.

What is PKU?

1. Phenylketonuria is a rare, genetic disorder in which cells are unable to produce an enzyme that converts the essential amino acid phenylalanine to other compounds, resulting in an accumulation of phenylalanine in the blood. a. Although phenylalanine is essential for growth and development, excessive accumulation of this amino acid in the blood leads to damage of nerve and brain cells, which may result in intellectual disability or behavioral problems. 2. Simple blood test after birth is used to diagnose PKU. 3. Treatment a. Special formula during infancy. Low-phenylalanine diet for life, which limits nuts, many animal foods, and food products sweetened with aspartame. i. Medication is available that helps some people with PKU metabolize phenylalanine. b. Frequent monitoring of blood levels of phenylalanine, especially during pregnancy.

Protein digestion & absorption

1. Protein digestion begins in the stomach, where HCl denatures proteins and pepsin breaks proteins into smaller polypeptides. 2. In the small intestine, pancreatic enzymes (including trypsin and chymotrypsin) break down polypeptides into shorter peptides and amino acids. 3. Absorptive cells of the small intestine release enzymes that further break down peptides to di- and tripeptides and amino acids that are absorbed. a. Di- and tripeptides undergo further breakdown into amino acids. 4. Eventually, the amino acids enter the hepatic portal vein.

Nitrogen balance

1. Some loss of nitrogen normally occurs by urinary elimination of urea and creatinine, growth of fingernails and hair, and shedding of cells from skin and GI tract. 2. Nitrogen balance (nitrogen equilibrium): nitrogen intake and protein turnover equal nitrogen losses.

Polypeptide

A polymer (chain) of many amino acids linked together by peptide bonds.

Understanding Nutritional Labeling: Protein

A. Protein content is required on Nutrition Facts panel, but not the %DV for protein (adult foods). B. Protein quality is not indicated, but it can be ascertained by reviewing the ingredients' list.

Peptide bond

The chemical bond that forms between the carboxyl group of one amino acid and the amino group of another amino acid

Dipeptide

Two amino acids bonded together

Signs & symptoms of celiac disease

a. Malnutrition results from lack of healthy villi. b. Diarrhea, abdominal bloating, and weight loss c. Other health effects include anemia, osteoporosis, infertility, liver disease, and intestinal cancer from untreated celiac disease. d. Some people with celiac disease have no obvious signs or symptoms. e. If left untreated, celiac disease can result in serious health problems: anemia, osteoporosis, infertility, liver disease, and intestinal cancer. 3. As many as 1 in 141 people have celiac disease in the United States. 4. Disease is probably inherited but environmental factors may trigger the condition. 5. Diagnosis is made through blood testing and intestinal biopsies. 6. Treatment of food allergies involves strict avoidance of gluten-containing foods. 7. Refer students to the 8. Gluten sensitivity is not the same as celiac disease

Nutritional risks of poorly-planned vegetarian diets

a. May be low in energy (children) b. Low in omega-3 fatty acids c. Low in vitamins B-12 and D d. Low in iron, zinc, and calcium e. Low in certain essential amino acids

Nutritional advantages of well-planned vegetarian diets

a. More fiber b. More soy protein c. More folate, beta-carotene, vitamins C and E d. More magnesium and potassium e. More phytochemicals f. Often provide less saturated fat and cholesterol

Protein energy malnutrition (PEM)

a. PEM affects people whose diets lack sufficient protein and energy. b. Children are especially affected by undernutrition because they have relatively high needs to support growth, but their small stomachs limit the volume of plant sources of protein they can eat. i. Poor growth, permanently stunted ii. Weakness iii. Irritability iv. Susceptible to infections that can kill them v. Children who survive into adulthood may have stunted growth and lower intelligence when compared to adults who were adequately nourished during childhood.

High-risk groups for nutrient deficiencies with plant-based diets

a. Vegan children may not obtain adequate energy and protein due to early satiety from a high-fiber (bulky) plant food diet. b. Breast milk of vegan mothers may be deficient in vitamin B-12, which could affect the infant's development; requires B-12 supplementation. c. Pregnant vegans should consult with their physician about the need for B-12 supplement. d. Vegetarian teens may have higher risk developing eating disorders.

Lactoovovegetarian

consumes milk and eggs but no other animal foods

Lactovegetarian

consumes milk and milk products but no other animal foods

Vegan or total vegetarian

consumes no animal products

Tripeptide

three amino acids bonded together

Nutritional genomics

1. Relatively new science investigates the complex interactions among gene functioning, dietary choices, and the environment. a. Nutrigenetics is the study of how a person's genetic makeup affects the way his or her body responds to food. b. Nutrigenomics studies how nutrients and other food components can affect a person's genetic expression. c. Gene expression results in protein synthesis. 2. Nutritional genomics may explain why special diets or dietary supplements can have different effects on the health of different individuals 3. Genetic testing kits for home use are not well regulated. a. People interested in having genetic testing should consult their physician.

How to ensure vegetarians get adequate nutrition

4. Humans digest animal protein to a greater extent than plant protein. a. Vegetarians may need to increase protein intake. b. Total vegetarians can obtain adequate amounts of amino acids by eating quinoa, soy products, and foods that combine complementary plant proteins. 5. Vegetarians who do not eat fish may need to obtain DHA and EPA (omega-3 fatty acids) by taking supplements that contain certain algae or eating the algae. 6. Vegetarians can obtain adequate vitamins and minerals by consuming fortified foods and/or multivitamin and mineral supplements.

Protein Consumption Patterns

A. Protein supplies 16% of total kcal in typical American diet, which is within the AMDR (10 - 35% of total kcal). B. Americans consume more protein from animals than from plants. 1. Red and processed meat consumption is associated with increased risk of CVD and certain kinds of cancer, especially colorectal cancer. a. Red meat is high in saturated fat; processed meat is high in sodium. C. MyPlate: Recommendations for protein intake 1. Animal sources of protein are often rich sources of saturated fat. 2. Lean or low-fat sources of protein should be emphasized: a. Poultry b. Beef: round steaks, top round, loin, top sirloin, chuck roast, arm roast, extra lean ground beef 3. Trim visible fats from meats before cooking. 4. Vary protein choices by including fish (omega-3 fatty acids) and plant sources of protein.

Kwashiorkor (form of PEM)

a) Occurs when child is weaned from breast milk to a protein-deficient diet of cereal grains; diet is adequate in calories but deficient in high-quality protein. b) Stunted growth c) Unnaturally blond, sparse, brittle hair d) Discolored skin e) Some subcutaneous (under the skin) fat f) Swollen cheeks, arms, legs, and bellies due to edema g) May progress to marasmic kwashiorkor, which is characterized by edema and wasting (body proteins are broken down to amino acids for energy)

High-quality (complete) protein

a. Contains all essential amino acids in amounts that support protein deposition in muscles and other tissues and will support a young child's growth b. Egg protein generally rates high in quality i. Well digested ii. Pattern of amino acids that closely resembles the pattern needed by humans c. Dietary sources: most animal sources of protein (except, gelatin)

The liver is the main site of production of nonessential amino acids

a. Deamination removes the nitrogen-containing group from an amino acid to leave a carbon skeleton. b. Transamination transfers the nitrogen-containing group from one amino acid to another substance to make a new amino acid (reversible). c. Byproduct of deamination reactions is ammonia (NH3), which is highly toxic. d. The liver converts ammonia to urea, which travels through the blood to the kidneys for excretion. e. The carbon skeleton that remains after deamination of an amino acid can be used for energy or converted into other compounds. 5. Unneeded amino acids are deaminated, converted into glucose or fat, which is then metabolized for energy or stored as fat.

Classifying amino acids

a. Essential amino acids (indispensable) cannot be made or made in sufficient quantities by the human body to support human needs; must be consumed in the diet. b. Nonessential amino acids (dispensable) can be made by the body from other amino acids. c. Under certain conditions, a few nonessential amino acids become essential.

Low-quality (incomplete) protein

a. Lacks or has inadequate amounts of one or more of the essential amino acids b. Inefficient digestion c. Limiting amino acids: those essential amino acids that are lacking or inadequate in a low-quality protein (usually tryptophan, threonine, lysine, methionine, and cysteine) i. The insufficiency limits the body's ability to utilize the protein. d. Dietary sources: plant sources of protein, with the exception of soy protein and quinoa, which are good plant sources of high-quality protein

Proteins in Food

a. animal sources generally have higher amounts of protein/serving than plant sources but no naturally occurring food is 100% protein b. plant sources of protein: 1. Seeds 2. Legumes are plants that produce pods that have a single row of seeds (e.g., soybeans, peas, peanuts, lentils, and beans) 3. Tree nuts (e.g., walnuts, cashews, almonds) b. Seeds, tree nuts, and legumes generally provide more protein than fruit or the stems, leaves, roots, and flowers of vegetables.

Pescatarian

eats fish and shellfish, but no other sources of animal protein