Proteins
Kwashiorkor
Sudden or recent loss of protein containing food. Esp. During a famine Causes fat to accumulate in the liver Lack or protein and hormones result in edema, painful skin lesions, and changes in the pigmentation of skin and hair. High mortality rate
Marasmus
Protein energy malnutrition as well as vitamins and minerals. Severe wasting caused by lack of protein and all nutrients or faulty absorption. Appearance is emaciated, but does NOT have edema, dull & dry hair, skin is thin & wrinkled
Albumin
Protein in blood plasma. A deficiency of albumin causes edema (swollen appearance). Symptoms include lethargy and depression. Signs found in grossly neglected children, elderly, poor, or incapitated.
Gelatin
The only incomplete protein that comes from an animal source
Protein Energy Malnutrition
Lack of protein and energy rich food. Not uncommon in developing countries.
Composition of Proteins
Like CHO & fats they contain carbon, hydrogen, & oxygen but in diff. Proportions. But it also contains NITROGEN & some contain sulfur. Composed of chemical compounds called amino acids (building blocks of protein)
Building & Repairing Body Tissue (Function of proteins)
Primary fxn of proteins. As cells are broken down during metabolism (CATABOLISM) some amino acids released in to the blood are RECYCLED to build and repair tissues (ANABOLISM) The body uses recycled amino acids as efficiently as those obtained in diet
Deamination
Process where the nitrogen containing amine group is stripped off when amino acids are broken down. Deamination produces AMMONIA which is released into the bloodstream by the cells. The LIVER picks up the ammonia to convert it to UREA. Urea returns to bloodstream for the KIDNEYS to to filter and excrete. The remaining parts are used for energy or are converted to CHO or fat & stored as GLYCOGEN or adipose tissue.
Infants born to mothers eating insufficient proteins during pregnancy
Can have impaired mental capacities
10 Essential Amino Acids
*Arginine *Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine
Proteins
10-35% of diet
Complete proteins should be limited
Because many contains sat. Fats & cholesterol that may contribute to heart disease and provide excessive calories. Long term high protein intake has a connection with colon cancer and high calcium excretion (leads to osteoporosis) Excessive proteins usually mean people ignore fruits & veggies which puts more demand on the liver (converts nitrogen to urea) & kidneys to excrete the urea.
Mechanical digestion
Begins in the mouth
Chemical digestion of proteins
Begins in the stomach. Hydrochloric acid prepares the stomach so that the enzyme PEPSIN can begin to reduce proteins to POLYPEPTIDES (10 or more essential amino acids bonded together) After polypeptides reach the SMALL INTESTINE the three pancreatic enzymes (trypsin, chymotryspin, & carboxypeptidase---these are essential for the digestion of proteins) continue chemical digestion. After digestion, the amino acids in the SMALL INTESTINE are absorbed by the VILLI & carried by the BLOOD to all body tissues to be used to form proteins.
Classification of a protein
Depends on the types & number of amino acids it contains
Protein Requirements
Determined by age, sex, size, and physical and emotional conditions. AVG Adult daily intake should be .8 g of protein per kg of body weight. 10-35% of daily calorie intake
Heredity
Determines the specific types of proteins within each person
Physical trauma
Extreme physical stress
Animal Food Source
Highest quality of COMPLETE PROTEINS (most complete proteins with sat. fat & cholesterol) Meats, fish, milk, eggs, poultry, & cheese Should be selected from low-fat animal foods such as fish and skim milk
Plant Food Source
Incomplete proteins (lower biological quality than animal source) Corn, grain, nuts, sunflower seeds, sesame seeds, legumes, soy beans, pinto beans, navy beans, chickpeas, peanuts, and split peas Plant proteins can be combined to create ANALOGUES (meat alternatives that have good sources of proteins, iron, & B vitamins)
Complementary Proteins
Incomplete proteins that when combined provide all 10 essential amino acids Corn & Beans Rice & beans Bread & PB Bread & split pea soup Bread & cheese Bread & baked beans Macaroni & cheese Cereal & milk
Survivors of kwashiorkor and marasmus
May suffer mental retardation
Negative nitrogen balance
More nitrogen excreted than taken in. Caused by burns, surgery, starvation, or immobilization
Protein deficiency
Muscle wasting Thinning of extremities. Albumin deficiency-> edema
Amino Acids
Nitrogen containing compounds. End products of protein metabolism
Positive nitrogen balance
Nitrogen intake exceeds outgo or excretion. Indicates new tissue is being formed. Present during pregnancy, child development, development of new muscle, & after physical trauma
Essential amino acids are needed for
Normal growth & development. Must be provided in the diet.
Regulating Body Functions (Fxn of protein)
Proteins are important for hormones and enzymes that are needed for metabolism and digestion. Proteins maintain electrolyte balance and prevents edema. Proteins are essential for development of antibodies which makes a healthy immune system
Providing Energy (Function of a protein)
Proteins can supply energy if and when the CHO & fat supply is insufficient Each gram of protein provides 4 calories Most complete proteins contain saturated fats and cholesterol
Complete proteins
Proteins containing all essential amino acids Bioavailable (high biological value) Found in animal sources Most contain sat. fats and cholesterol
Incomplete Proteins
Proteins that do not contain all the essential amino acids Cannot build tissues without the help of other proteins Eaten with other incomplete protein throughout the day to provide the essential amino acids that one may lack (COMPLEMENTARY PROTEINS)
Tofu
Soft cheese like food made from soy milk. Rich in B vitamins and proteins but low in sodium Economical and nutritious analogue
Vegetarian Concern
Those who consume no animal product should include other protein rich food sources such as soy beans, soy milk, and tofu
Nitrogen balance
When nitrogen intake equals nitrogen excreted.