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Human Nutrition. Digestive System. Nutrients: Utilized or Stored Until Needed. Food Guide Pyramid. Diet and regular exercise. Nutrition - Macronutrients. Carbohydrates: major energy source, simple or complex. Metabolic rate related to glycemic index
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Food Guide Pyramid Diet and regular exercise
Nutrition - Macronutrients • Carbohydrates: major energy source, simple or complex. Metabolic rate related to glycemic index • Lipids: cell components and energy sources, saturated or unsaturated, transfats, omega oils • Proteins: 20 natural amino acids, building and repair, hormones, enzymes • Water: solvent, thermoregulation, metabolic processes
Nutrition - Micronutrients • Vitamins: fat soluble and water soluble • Minerals: recommended daily allowance (rda) • Fiber: some evidence decreases colon cancer
Carbohydrates • General formula ratio is for most carbohydrates is CH2O • Carbohydrate rich foods in their natural state are low in calories and high in fiber (AKA as cellulose, plant fibers we do not digest). • Carbohydrates contain about 4 calories per gram (fats about 9 cal per gram).
Simple Carbohydrates • Also called simple sugars. • Simple carbohydrates include monosaccharides and disaccharides such as: • fructose (fruit sugar), • sucrose (table sugar) and • lactose (milk sugar), as well as several other sugars. • Simple carbohydrates are sources of quick energy.
Complex Carbohydrates • Complex carbohydrates include fiber and starches. • Found in vegetables, bread, rice, oatmeal, whole grains, peas and beans. • Meats also provide carbs in the form of glycogens.
Complex Carbohydrates • Complex carbohydrates take longer to be digested, so your body needs more time to release these carbs into your blood as glucose. • This results in sustained energy (stamina). • SEE GLYCEMIC INDEX
Undigestible Complex Carbohydrates • Also called fiber • Essential role in large intestine health • “Brushes” walls of large intestine
When we eat carb rich foods, our blood glucose levels increase dramatically. • our pancreas secretes insulin so that glucose units can be taken into body cells for use in respiration (producing ATP). • Insulin and diabetes Carbohydrates
In times of not eating, our brain still needs glucose, our muscles still need glucose • This stimulates the pancreas to produce the hormone glucagon which converts glycogen stored in the liver into glucose. • If there is still insufficient glucose, the liver metabolizes fats and converts these molecules into glucose. Blood Sugar
Glycemic Index • High glycemic foods are used quickly and stored as fat tissue easily. • Low glycemic foods provided more long term energy and reduced insulin levels (which is a good thing).
Glycemic Index • The effect of eating high glycemic index foods consistently is to lead to constantly high insulin levels. • In this situation, the body becomes accustomed to these high insulin levels and starts to respond to them less effectively over time.
Glycemic Index • As high glycemic index foods are eaten further, this progresses, more and more insulin is required to have the same effect on the tissues. • This phenomenon is known as insulin resistance, and is the first step towards diabetes.
Lipids • Triglycerides have the general elements are C, H, O like carbs except they have much less O. They are made of glycerol and fatty acids. • Glycerol is a small, 3-carbon molecule with three hydroxyl groups.
Lipids • Fatty acids are long molecules with a polar, hydrophilic end and a non-polar, hydrophobic "tail". The hydrocarbon chain can be from 14 to 22 CH2 units long *even number of C.
Saturated Fats • If there are no C=C double bonds in the hydrocarbon chain, then it is a saturated fatty acid (i.e. saturated with hydrogen). • These fatty acids form straight chains, and have a high melting point. • Sources are animals: • butter and • lard (solid at room temp.)
Unsaturated Fats • If there are C=C double bonds in the hydrocarbon chain, then it is an unsaturated fatty acid (i.e. unsaturated with hydrogen). • These fatty acids form bent chains, and have a low melting point.
Unsaturated Fats • Fatty acids with more than one double bond are called poly-unsaturated fatty acids (PUFAs). • Cold blooded animals (fish) and plants are sources: omega fatty acids, flax, olive oil, canola and sunflower oil.
Triglycerides • Triglycerides are insoluble in water. • They are used for storage, insulation and protection in fatty tissue (or adipose tissue) found under the skin (sub-cutaneous) or surrounding organs. • They yield more energy per unit mass than other compounds so are good for energy storage (about 2X more energy).
DIETARY CONSIDERATIONS • In food chemistry, HYDROGENATED margarine is plant unsaturated fatty acid which has had H added back to its structure. • This results in a margarine which is more solid and able to with-stand higher temperatures. • Most unsaturated fats are liquids (olive oil, canola oil are liquid at room temperature).
DIETARY CONSIDERATIONS • TRANS FATS: Unsaturated fats have a structure with kinks; these kinks result in a liquid state at room temperature. • In the early 20th century, a chemical process called hydrogenation was developed that converts vegetable oils into saturated, more solid fats (margarine and vegetable shortening).
DIETARY CONSIDERATIONS • When it was discovered that eating saturated fats increases the risk for coronary heart disease, the food industry turned to partial hydrogenation. • This process lowered the content of saturated fat in vegetable shortening and margarine, but also dramatically increased the amount of a certain kind of fat - trans fat - in our diets, as an unavoidable side reaction.
DIETARY CONSIDERATIONS • While suppliers praised processed vegetable oils as healthy unsaturated and cholesterol-free substitutes for animal fats, there is now strong evidence that introducing trans-fatty acids into our diets does more harm than good.
Phospholipids • Phospholipids have a similar structure to triglycerides, but with a phosphate group in place of one fatty acid chain. • There may also be other groups attached to the phosphate.
Phospholipids • Phospholipids have a polar hydrophilic "head" (the negatively-charged phosphate group) and two non-polar hydrophobic "tails" (the fatty acid chains). • This mixture of properties is fundamental to biology, for phospholipids are the main components of cell membranes.
Waxes Waxes are formed from fatty acids and long-chain alcohols. They are commonly found wherever waterproofing is needed, such as in leaf cuticles, insect exoskeletons, birds' feathers and mammals' fur.
Waxes - Cholesterol CHOLESTEROL is like a fatty wax. Normally made in the liver, it is structural component of nerve tissue and cell membranes. It is also used to make various steroid hormones including progesterone, testosterone (sex hormones in females and males) estradiol, and cortisol. Bile salts are breakdown products of cholesterol.
Waxes Blood is watery, and cholesterol is fatty. Just like oil and water, the two do not mix. To travel in the bloodstream, cholesterol is carried in small packages called lipoproteins. The small packages are made of fat (lipid) on the inside and proteins on the outside. Two kinds of lipoproteins carry cholesterol throughout your body.
Waxes It is important to have healthy levels of both: Low-density lipoprotein (LDL) cholesterol is sometimes called bad cholesterol. High amounts of LDL cholesterol leads to a build up of cholesterol in arteries. The higher the LDL level in your blood, the greater chance you have of getting heart disease.
Waxes These form plaques along arteries. When it hardens the arteries we call it arteriosclerosis. These can dislodge to plug smaller arteries or veins—heart attacks or strokes are possible. They can completely block a vessel resulting in an embolism, aneurism, heart attack, stroke.
Waxes High-density lipoprotein (HDL) cholesterol is sometimes called good cholesterol. HDL carries cholesterol from other parts of your body back to your liver. The liver removes the cholesterol from your body. The higher your HDL cholesterol level, the lower yourchance of getting heart disease.
Things that TEND to increase LDL levels: Overweight Physical inactivity• Cigarette smoking Excessive alcohol use Physical inactivity Very high carbohydrate diet Certain diseases and drugs Genetic disorders.
Proteins The polymer of amino acids does not remain like a long chain but folds into a three-dimensional shape which is the most stable for that sequence of amino acids. This shape is called the native conformation for that particular protein and is essential for that protein's biological activity. i.e. shape is everything
Proteins The shape may be altered by various factors e.g. heat or large pH changes. Once the three-dimensional shape is altered, biological activity is lost. The building blocks of proteins are amino acids These are arranged in a very specific order – determines shape
Essential & Non-Essential AA’s • As far as your body is concerned, there are two different types of amino acids: • essential and non-essential. • Non-essential amino acids are amino acids that your body can create out of other chemicals found in your body. • Essential amino acids cannot be created, and therefore the only way to get them is through food.
Protein • Protein in our diets comes from both animal and vegetable sources. Most animal sources (meat, milk, eggs) provide what's called "complete protein," meaning that they contain all of the essential amino acids. • Vegetable sources usually are low on or missing certain essential amino acids. For example, rice is low in isoleucine and lysine.
Balancing AA’s • However, different vegetable sources are deficient in different amino acids, and by combining different foods you can get all of the essential amino acids throughout the course of the day. • This balancing of amino acids is essential because if one amino acid is deficient, an entire protein cannot be made sufficiently.
Vegetarian Diets • Vegetarians need to balance plant source proteins—eg. Rice with beans. • Some vegetable sources contain quite a bit of protein -- things like nuts, beans, soybeans, etc. are all high in protein. By combining them you can get complete coverage of all essential amino acids.
Types of Vegetarian Diets • Pescatarian – may include fish but no chicken, beef, pork • Flexitarian – may include some meat time to time • Lacto-Ovo vegetarian – includes milk products and eggs but no meats • Vegan – do not include any animal products including processed foods that may include animal products like gelatine, honey.
To Get Protein RDA • The digestive system breaks all proteins down into their amino acids so that they can enter the bloodstream. • Cells then use the amino acids as building blocks.
This photo is the Nutritional Facts label from a can of tuna. • According to the RDA (Recommended Daily Allowance) for protein is 0.36 grams of protein per pound of body weight. So a 150-pound person needs 54 grams of protein per day. • From this you can see that your body cannot survive strictly on carbohydrates. You must have protein.
