Chapter 7 (part 1): Proteins Foods: Fall 2013

Protein: The main Idea  Very important in the diet.  Contribute to growth and development.  Help the body repair itself.  Found in many foods:  Meat  Poultry  Fish  Eggs  Dairy Products  Beans  Peas  Nuts  Vegetables  Grain products

The Structure of Proteins  Make up 1/5 th of your body’s total weight.  Part of every cell, all tissues, and organs.  Very complex molecules.  Made up of amino acids  Amino acids can link together in many different ways.  22 different amino acids have been identified.  When combined amino acids form many different shapes.  Shape determines function of the amino acid.

Protein Digestion  Digestion of protein begins in the stomach.  The stomach acid changes the shape of the protein.  Then each molecule is broken down into individual amino acids.  The amino acids are then absorbed in the bloodstream.  Upon reaching the cells amino acids can be used to make protein for specific purposes.

Complete and Incomplete Proteins  Your body can make many amino acids for itself, but not all the amino acids it needs.  Essential Amino Acids = amino acids that your body needs but cannot provide. You must get these through foods.  Complete Protein = foods from animal sources that have all of the needed amino acids  Incomplete Protein = foods from plant sources that do not have all of the essential amino acids.  When your body is lacking essential amino acids it cannot build the proteins you need.

Why we need Protein  Growth and maintenance – new cells are needed for growth. Hair, eyes, teeth, skin, muscles, and bones are made up of proteins.  Enzymes – help with chemical reactions in cells  Hormones - chemical messengers that help regulate conditions in the body.  Antibodies – fight invaders and sickness. Made only when needed.  Fluid balance – Helps regulate cell health by keeping a balance

How munch protein do we need?  Experts recommend 10-30% of your calories should be from proteins.  Larger people need more protein than smaller people.  During certain periods of a person’s life you may need more.  Pregnant and breast feeding women  Infants  Children  Teens

Excess Protein  Too much can be harmful.  Excess is broken down and stored as fat.  Healthy people should not need supplements.  Should get all of the proteins and amino acids you need by eating a variety of food.

Lack of Protein  Is a serious problem in 3 rd world countries.  Protein Energy Malnutrition (PEM) – is a leading form of malnutrition in the world.  Children are especially affected.  With PEM loose weight and don’t grow properly.  Can even die of starvation.  Can also affect those with eating disorders or drug/alcohol addiction.