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.