Macronutrients and Micronutrients

Macronutrients and micronutrients Carbohydrates • • • Most important energy source Precursors for glycoproteins, glycolipids and mucopolysaccharides In two forms: - Simple sugars: little ring-shaped molecules made out of carbon, hydrogen, and oxygen. This includes monosaccharides and oligosaccharides ✓ Directly absorbed into the GIT - Complex sugars: formed when simple sugars are linked together. This includes polysaccharides ✓ Need to be acted upon via maltase, lactase and sucrase Maltose Lactose Sucrose Maltase Lactase Sucrase • • • • • • Structure Broken by Sources Fibre • • • • • • • • • Pancakes Sweet potatoes French bread Fried onions Bagels Pizza Burgers Apple pies Green soybeans Milk Cheese Anything diary • • Sugar Chocolate Deep fried chicken with sweet sauce Cookies Fast foods - The indigested parts of plants It cannot be broken down into simple sugars, thus it goes through the body undigested and unabsorbed Types: soluble and insoluble Functions: ✓ Cholesterol lowering levels: Soluble fiber lowers cholesterol by binding to it in the small intestine. Once inside the small intestine, the fiber attaches to the cholesterol particles, preventing them from entering your bloodstream and traveling to other parts of the body. Instead, cholesterol will exit the body through the faeces ✓ Control of blood glucose levels: this because it is not digested thus does not cause a huge increase in your blood glucose levels -> keeps blood sugar in target range ✓ Prevent constipation increases weight and size of stools, as bulkier stools are more likely to pass -> thus preventing constipation Low GI vs. high GI food - Low GI: slowly digested -> slower rise in glucose levels High GI: rapid digestion -> higher rise in glucose levels Proteins Structure • • Made out of amino acids Rich source of amino acids and nitrogen Function • • • Growth and repair of body cell tissues Synthesis of enzymes, plasma proteins and antibodies Provision of energy, when both glucose and lipids fail to provide energy Lipids Structure • Most concentrated form of energy • • Consist of carbon, hydrogen and oxygen, but they differ from carbohydrates in that the hydrogen and oxygen are not in the same proportions as in water Classified into several groups: - Triglycerides: ✓ 3 fatty acids linked to a glycerol molecule ✓ Can be classified as saturated or non-saturated ✓ Saturated are solid at room temperature and originate from animal sources ✓ Unsaturated fats are derived from plant sources - Cholesterol: ✓ Has a structure of four rings which give it is steroid structure (unlike those how are arranged in chains) ✓ Needed for steroid hormone synthesis and for making the cell membrane ✓ LDL: carry cholesterol from liver to body cells, too much is toxic as it can build up in arterial walls and cause arteriosclerosis ✓ HDL: carries cholesterol from body cells to liver ✓ High cholesterol levels cause atherosclerosis, high blood pressure and type 2 diseases Functions • • • • • • Sources of energy and heat A, D, E and K vitamin absorption Makes myelin sheath Steroid hormone formation Insulation-> reduces eat loss from the skin Satiety value: emptying time of the stomach is prolonged after eating foods that are too high in fat -> postpone return to hunger