* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 14 Nutrition Nutrients A nutrient is a component of food that
Survey
Document related concepts
Biochemical cascade wikipedia , lookup
Citric acid cycle wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
Protein–protein interaction wikipedia , lookup
Western blot wikipedia , lookup
Two-hybrid screening wikipedia , lookup
Signal transduction wikipedia , lookup
Fatty acid synthesis wikipedia , lookup
Genetic code wikipedia , lookup
Protein structure prediction wikipedia , lookup
Amino acid synthesis wikipedia , lookup
Biosynthesis wikipedia , lookup
Basal metabolic rate wikipedia , lookup
Proteolysis wikipedia , lookup
Transcript
Chapter 14 Nutrition Nutrients A nutrient is a component of food that is needed to perform a physiological body function Nutrients include: o Carbohydrates o Proteins o Lipids o Minerals o Vitamins Carbohydrates Sugars or polysaccharides that are digested into simple sugars that serve an important energy source for cells Refined grains should be minimized in the diet because the important fiber and vitamins are removed (i.e. white bread, cake, and cookies) Complex carbohydrates are recommended as a good source of vitamins and minerals (i.e. beans, whole-grain products, nuts, and fruits) Can carbohydrates be harmful? Refined sugars and fructose sweeteners may contribute to obesity These foods may cause the pancreas to secrete large amounts of insulin which can lead to insulin resistance seen in type 2 diabetes and increased fat metabolism An increase in fat deposition may increase the risk of coronary heart disease, liver diseases, and certain cancers Lipids Includes fats, oils, and cholesterol Saturated fats (usually of animal origin) are usually solid at room temperature while unsaturated fats are usually liquid at room temperature Essential fatty acids are ones that must be ingested including linoleic acid and linolenic acid (these can only be found in polyunsaturated oils such as corn and safflower) Olive and canola oil contain more monounsaturated fats Omega-3 fatty acids, thought to ward off heart disease, are found in some fish (salmon, sardines, and trout) as well as some plants (flaxseed oil) Choosing the most healthy fat and oil Can lipids be harmful? CVD is often a result of arteries blocked by plaque made of cholesterol and saturated fats Low density lipoproteins (LDL) are the “bad” cholesterol because they carry cholesterol from the liver to the cells LDL is increased by saturated fats and decreased by unsaturated fats High density lipoproteins (HDL) is the “good” cholesterol because it carries cholesterol to the liver where it is converted to bile salts Trans-fatty acids are made by hydrogenation of unsaturated fatty acids for commercial products and may reduce the ability of cells to clear cholesterol from the bloodstream Proteins Proteins are digested into 20 different amino acids which are used to produce our own cellular proteins Essential amino acids are the 9 amino acids that must be attained through diet o Complete proteins that have all of the essential amino acids are usually derived from animals such as meat and dairy o Non-animal sources of complete proteins are tofu, soymilk, and other processed food from soybeans o Incomplete proteins are ones that lack at least one essential amino acid (i.e. legumes, nuts, grains, etc…) and need to be combined with another incomplete protein to provide all of the essential amino acids to be used in the body Amino acids cannot be stored in the body thus small amounts (2 meat servings) need to be ingested on a daily basis Can proteins be harmful? o An overabundance of protein can result in dehydration during exercise and sweating o An overabundance of proteins can lead to calcium loss in urine which can lead to kidney stones o Eating red meat as a source of protein is high in saturated fats that can lead to CVD Food groups Food groups are not nutrient classes However, they are easier for most people to deal with Vitamins Organic compounds (other than proteins, fats, or carbohydrates) used for metabolism that are not produced in enough quantity by the body Vitamins are often enzyme helpers (coenzymes) There are a total of 13 vitamins in two groups: fat-soluble and water soluble Antioxidants Are chemicals that decrease the rate of oxidation or transfer of electrons Vitamins C, E, and A are considered antioxidants because they are thought to defend the body against free radicals that can transfer electrons and damage cells and DNA o The vitamins are common in fruits and vegetables Minerals The body contains > 5g of each major mineral and < 5g of each trace mineral Major minerals make up components of cells, body fluids, and tissues (i.e. calcium) Minor minerals are components of larger molecules (i.e. iron in hemoglobin) A varied and complete diet usually provides all of the necessary minerals Calcium o Needed for nerve impulse conduction, muscle contraction, and to make bone o 1,000mg/day is recommended to keep bones healthy early in life and 1,300mg/day after menopausal age o Vitamin D is needed with calcium to prevent bone loss (osteoporosis) Sodium o Needed for regulating water balance o 500mg/day is the recommended amount (on average each American takes in 4,000 − 4,700mg/day) o Sodium can increase hypertension in people who already have it Metabolism o Metabolism consists of all of the chemical reactions that we carry out to break down our nutrients and build up our macromolecules o Catabolism is the breakdown of nutrient molecules to produce energy o Anabolism is the building up of complex molecules from simpler building blocks, requiring energy Cellular respiration o Glycolysis is the initial set of catabolic reactions occurring in the cell cytosol o Converts glucose into 2 pyruvate molecules o Produces a very small amount of ATP o If oxygen is available, the rest of the reactions occur in the mitochondria o In the mitochondria, the molecules are converted to CO2 with the release of energy to form ATP o Krebs cycle, ETC, and chemiosmosis Glucose in the body o Most of the carbohydrates we consume are broken down to glucose which is then broken down to produce ATP o Some glucose is stored in the form of glycogen stored in muscle and liver cells o Unfortunately, we can only store a limited amount of glucose as glycogen Fats in the body o Fats can be catabolized to produce ATP o Unfortunately, when we have excess calories from our diet, convert the excess glucose into lipids called triglycerides o The triglycerides are stored in fat cells, adipocytes, causing them to get larger o The result is fat deposition in our bodies What is obesity and BMI? o When an individual is grossly overweight and has a body mass index (BMI) ≥ 30 o BMI is a general guide to estimate how much of a person’s weight is due to adipose tissue o It does not take into account gender, fitness, or bone structure o caloriesperhour.com Why should we be concerned with obesity? o Occurrence has doubled in the US in the last 20 years o In the US, ~1/3 of adults are obese and it is now prevalent in children and adolescents o Obesity tends to increase with an increase in income o It is associated with an increased risk of premature death, type 2 diabetes, hypertension, CVD, stroke, gallbladder disease, respiratory disfunction, osteoarthritis, and certain cancers