Micronutrients PDF

Micronutrients Eman Abdelrazek Elhelbawy Proffessor of clinical oncology and nuclear medicine Menofia University Clinical nutrition in health care Diploma Tanta Unversity  Objectives  Micronutrients  Vitamins  Minerals ...

Micronutrients Eman Abdelrazek Elhelbawy Proffessor of clinical oncology and nuclear medicine Menofia University Clinical nutrition in health care Diploma Tanta Unversity  Objectives  Micronutrients  Vitamins  Minerals  Micronutrients??? Vitamins and minerals are essential for good health yet cannot be isolated from the food that contains these vital substances. Vitamins  Until the start of the 20th century that these factors were named vitamins and, at the beginning of the 21st century, became a multibillion-dollar industry.  Vitamins are separated into two classes:  Fat-soluble vitamins: (A, D, E, and K) are absorbed along with fats in the diet and are stored in the body’s fatty tissue and liver. These vitamins play critical roles in vision, bone health, immune function, and coagulation.  Water-soluble vitamins: (all other vitamins besides A, D, E, and K) are dissolved in water. Excess intake of water-soluble vitamins is excreted in the urine. All vitamins are found naturally in foods and have specific functions. In general, vitamins play the following essential roles: Boost the immune system Decrease the risk for certain cancers Strengthen teeth and bones Maintain healthy skin Help the body metabolize proteins and carbohydrates Support healthy blood Aid brain and nervous system functions Vitamins A, D, E, and K  Fat-soluble vitamins, like dietary fat, are absorbed through the lymphatic system and then released into the blood, carried by transport proteins. Because these vitamins are stored, daily intake is not required.  Excess intake of fat-soluble vitamins, as found with some supplements, can cause toxicity and side effects from taking large doses of supplements or medications.  Absorption of fat-soluble vitamins occurs in the small intestine where they are mixed with bile salts, fatty acids, and phospholipids; absorbed by chylomicrons (microproteins); and carried to the lymphatic system.  Since all vitamins require carrier proteins for transportation across the lipid bi-layer, absorption can be affected adversely by a genetic abnormality in the transport molecules. Vitamin A:  Vitamin A is active in the genetic development of retinol pigments and contributes to healthy bones, teeth, and soft tissue.  Vitamin A also plays a role in reproduction, facilitating semen production and cell differentiation in fetal development.  Vitamin A is critical in immune function, helping to grow the cells that produce the mucus that lines the gastrointestinal tracts, sinuses, and genitourinary tract.  Beta-carotene, a precursor to vitamin A is an antioxidant that protects against certain cancers and aging by stabilizing free radicals.  A free radical is an unstable molecule made during normal cell metabolism that has one unpaired electron. Vitamin D is a fat-soluble vitamin that closely resembles a hormone’s functions. This vitamin can trigger effects in tissue throughout the body, turning on and off the production of proteins. Vitamin D, like vitamin A, plays a role in immunity by promoting the secretion of infection-fighting substances found in white blood cells. Vitamin D naturally occurs in some foods (fatty fish and egg yolks), is added to others (like milk and orange juice), and is available as a vitamin supplement. Vitamin D is unusual because the body can synthesize it from a cholesterol precursor—7- dehydrocholesterol (7-DHC)—in the epidermis with the help of ultraviolet light. Vitamin D assists in promoting calcium uptake in the gut and ensures adequate calcium and phosphorus for bone mineralization. Bones can become thin, fragile, and deformed without sufficient vitamin D. Vitamin D prevents rickets, the softening of the bones, which results in bowed legs, and protects against osteoporosis, the loss of bone density, which leads to porous structure. Vitamin E: a fat-soluble vitamin, acts as an antioxidant and stops the development of free radicals during fat oxidation. Fat oxidation is a chemical reaction in which a healthy molecule loses or is robbed of one of its electrons, which then produces an unhealthy free radical. In addition to protecting the cell from reactive oxygen species (ROS) (reactive species capable of causing damage to biomolecules), vitamin E helps establish a robust immune system and improves the endothelial cells on the surface of blood vessels, making them more resistant to the adherence of clots. Vitamin K:  A fat-soluble vitamin, is a coenzyme required for blood clotting and bone metabolism.  Vitamin K is present in the liver and other body tissues, including the brain, heart, pancreas, and bone. Compared with other fat soluble vitamins, minimal amounts of vitamin K circulate in the blood due to rapid metabolism and excretion.  The clinical status of vitamin K should be regularly evaluated in individuals who take anticoagulants or have bleeding disorders. Infants are injected with vitamin K at birth to decrease the risk of a hemorrhagic event.  Because fat-soluble vitamins are stored in tissue, higher amounts of these vitamins result in toxicity. B Vitamins  There are eight B vitamins (at times referred to as B complex): thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5),pyridoxine (B6), biotin (B7), folate (B9), and cobalamin (B12).  All B vitamins act as coenzymes for catalytic activity and several processes that support every aspect of cellular function, including brain and nervous system functions.  Although almost all the B vitamins are involved in metabolism, one cannot be substituted for another. Therefore, a specific B vitamin deficiency is associated with a specific disease.  In general, deficiency diseases related to B vitamins are rare, partly because of the wide availability of these vitamins in everyday food items, but also because B vitamins that are commonly lost in food processing are added back into the food.  For example, when the bran and germ are removed from grains,leaving only the endosperm, B vitamins and vitamin E are also removed.  Food manufacturers add back the vitamins during food processing. This process is called food enrichment.  B vitamins must have macronutrients (carbohydrates, fat, and protein) available for energy production.  Taking a vitamin supplement instead of a balanced meal does not provide a substrate for coenzyme action.  Instead, obtaining vitamins through foods is preferred. Remember that none of the other B vitamins can cover a deficiency of another. Choline, Biotin, and Folate  Choline is an essential nutrient, not classified as a vitamin or a mineral, and is naturally present in food. Choline is often grouped with the B vitamins because it has similar functions. This nutrient is a source of methyl groups needed for many steps in lipid metabolism and is required to generate the neurotransmitter acetylcholine. Although the body produces some choline endogenously in the liver, the amount is sometimes insufficient; additional choline must be ingested through food sources.  Biotin (B7) is a water-soluble vitamin that works as a cofactor that catalyzes the metabolism of fatty acids, glucose, and amino acids. Biotin is found in many animal and plant foods.  Folate (B9) functions as a coenzyme in synthesizing ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).  Folate is also critical in the metabolism of amino acids required for normal cell division.  A lack of folate will result in large red blood cells, which is associated with megaloblastic anemia, a condition in which the bone marrow produces unusually large, structurally abnormal, immature red blood cells.  Large doses of folate can result in kidney damage.  The chemical structure of folate differs from the more commonly known folic acid. Folates are naturally found in foods, although folic acid is the fully oxidized form of the vitamin used in fortified foods and most dietary supplements. Vitamin C (Ascorbic Acid)  Vitamin C or ascorbic acid, a water-soluble vitamin, is best known for its coenzyme and antioxidant properties.  Vitamin C protects cells from premature aging caused by free radicals.  Free radicals are the leading cause of disease and inflammation, so vitamin C’s ability to neutralize those free radicals (acting as an antioxidant) is central to lowering heart disease and cancer risk.  Vitamin C also promotes collagen synthesis. Although collagen synthesis is required for maintaining normal vascular function, it also provides metabolic substrates for new blood vessel development (angiogenesis), enhancing blood supply, and bringing more oxygen to the tissues.  Vitamin C is necessary for a healthy immune system and increases the absorption of non-heme iron.  Large doses of vitamin C can have an adverse effect in people with a family history of kidney or gallstones. Minerals Mineral Function  Minerals are common in cereals, bread, meat, fish, milk, dairy, nuts, fruit (especially in dried form), and vegetables.  About 20 minerals are essential for body function, all in varying amounts depending on their role.  Minerals work synergistically. For example, the sodium-to-potassium ratio is essential in maintaining normal blood pressure.  The proper relationship between calcium and phosphorus is vital in maintaining normal bone structure.  As with vitamins, one mineral cannot assume the function of another mineral, and a shortage or deficiency of any mineral will impact body function  Mineral absorption takes place primarily in the small intestine.  For some minerals, absorption efficiency depends on specific needs such as calcium absorption in pregnancy. During pregnancy, calcium absorption takes place actively, which requires energy to transport across the cell membrane. In times of plentiful serum calcium, the body switches to a passive diffusion method of absorption.  Mineral absorption can be helped other dietary components that occur naturally in food. For example, iron is best absorbed in an acid environment, so health professionals recommend taking an iron supplement with orange juice. Mineral Intake for Wellness  Minerals play an essential role in various metabolic and physiologic processes. Minerals are critical for the metabolism of every cell in the body.  A well-balanced mineral intake is essential throughout the human life cycle, although specific needs may vary based on age and sex.  For example, the iron needs of premenopausal clients are higher than postmenopausal clients because of the iron loss during menstruation.  A diet comprised of vegetables, legumes, nuts, lean meats, and seafood provides all the essential minerals needed throughout a person’s life. THANK YOU