Nutrition

Nutrients Substances in foods that provide energy and materials for cell development, growth and repair Energy: –Every body activity needs energy. Ex: Heart beating, blinking, maintaining constant body temperature –Calorie: the amount of heat needed to raise the temperature of 1 kilogram of water 1 o C –Food Calories depend on the kinds of nutrients a food provides

Classes of Nutrients Proteins* Carbohydrates* Fats* Vitamins* Minerals Water * “Organic Nutrients” that contain carbon Foods containing carbohydrates, fats and proteins need to be broken down before your body can use them Water, vitamins and minerals are absorbed directly into the bloodstream

Proteins Proteins are large molecules that contain carbon, hydrogen, oxygen, nitrogen and sometimes sulfur. The body uses them to replace and repair body cells Proteins are made of smaller “building blocks” called amino acids Different foods contain different amounts of protein: –Meat, poultry, eggs, fish, peas, beans and nuts are all high in protein.

Amino Acids Your body can make thousands of proteins it needs from just 20 amino acids. Most of these are manufactured in the body but 8 “essential” ones come from the foods we eat. “complete proteins” contain all 8 of them. –Eggs, milk, cheese and meat “incomplete” are missing one or more Vegetarians should eat a wide variety of protein-rich vegetables, fruits and grains

Carbohydrates Molecules made of carbon, hydrogen and oxygen, held together by energy. Are usually the main source of energy for the body, which is released when the molecule is broken down in your cells Three main types are sugars, starch and fiber. Sugars are “simple carbs” like Glucose Starch and fiber are “complex carbs” –Potatoes, pasta –Fiber is not digested but aids the system

Fats (Lipids) Provide energy and help the body absorb vitamins. Help cushion body organs. Cell membranes are partly fat. They can release more energy than carbohydrates During digestion they are broken down into smaller molecules called fatty acids and glycerol Excess energy from food you eat is stored as fat for use later.

Saturated and Unsaturated Fats Unsaturated fats are usually liquid at room temperature: vegetable oils and fats from seeds are unsaturated. Saturated fats are found in meats and animal products and some plants and are usually solid at room temperature Saturated fats are associated high levels of blood cholesterol. A diet high cholesterol can result in deposits forming on the walls of blood vessels.

Vitamins Organic nutrients needed for growth, regulation of body functions and disease prevention. Water-soluble: –Not stored in body, need to be replaced daily –B’s (B 6, B 12, riboflavin, niacin, thiamine) and C Fat-soluble: –Stored in the fatty tissues of the body –A, D, E, K

Minerals Inorganic nutrients (no carbon) Help regulate many chemical reactions The body uses 14 minerals –Calcium, Phosphorus, Potassium, Sodium and iron are common minerals –Help build cells, aid chemical reactions, send nerve impulses and carry oxygen to cells Trace minerals appear in small amounts: Copper and Iodine

Water 2nd to oxygen in importance You can live only a few days without water Most nutrients need to be dissolved in water and chemical reactions take place on solutions The human body is about 60% water by weight and about 2/3 of body water is in body cells. You need to replace 2.1 L of fluid daily, some of which is found in foods as well as in drinks!

Daily Water Loss Method of LossAmount (mL/day) Exhaled air350 mL Feces150 mL Skin (mostly as sweat)500 mL Urine1,500 mL