Part 1(due by 31th)This time we address two related topics.Calcium and Magnesium are two major minerals that have overlapping and independent roles in the body. Calcium supplements have been widely recommended,especially to adults at risk for osteoporosis.Magnesium is sometimes overlooked in the diet, even though it is an important cofactor for hundreds of metabolic reactions.In lecture 8(see the attachment) we focus briefly on potential problemswith excessive calcium supplementation. We also cover the issue of magnesium deficiency. You will be discussing bothminerals in this discussion - but for your main post, choose one of the two to concentrate on, though you may include information about its synergistic relationship with the other jif appropriate.You can include any or all of the following: food sources vs. supplements, the reason that calcium supplements are often soldcombined withmagnesium,risks/benefits of supplementation, challenges with obtaining adequate intake from food, factors that contribute to deficiency. Look at your own diets - do you feel you are at risk of deficiency for either mineral, if you care to share? What about excess or imbalance?Include, if appropriate,synergistic relationships with other nutrients that you learned about in Lecture 6 (Fat Soluble Vitamins).
Part II: reply to the following posts(in short) due by 2nd.I'll post it once you finished part 1.
Bio 125 Spring 2016 Lecture 8 Janine Grant MAJOR MINERALS Continued 1 Bio 125 Distance Learning Lecture 8 Janine Grant MAJOR MINERALS Continued Learning Objectives Explain the roles of Calcium, Phosphorus and Magnesium Their overlapping roles in bone structure Their individual functions in the body Discuss the role of Sulfur in the body 2 CALCIUM The most abundant mineral in the body. 99% of calcium is found in teeth and bone, remainder in blood and body fluid as ionized Ca++. Calcium is found in the bones along with phosphorus as solid mineral crystals called hydroxyapatite. Absorption and Metabolism Absorption Absorbed by active transport in duodenum as needed by the body when active form of vitamin D (calcitriol) is available. Very high intakes increase absorption by passive diffusion. The more you need, the higher the percentage absorbed. Stomach acid enhances absorption, forming calcium ions. Absorption is somewhat decreased by tannins, phytates, and oxalates, (see text and outline 7) and excess phosphorus intake. The trace mineral zinc competes for absorption Magnesium competes somewhat for absorption 3 3 Metabolism Blood concentration of calcium is tightly regulated by hormones: parathyroid hormone and calcitonin from the thyroid. (Review Vitamin D - Lecture 6) : Parathyroid hormone (PTH) is released in response to low blood calcium levels, increasing absorption, reducing excretion by the kidneys, and mobilizing calcium from bone. PTH increases Vitamin D levels (synthesis and activation in the kidney). Calcitonin decreases blood calcium, decreasing absorption, decreasing bone resorption, and increasing deposition to bones Functions Structure of teeth and bones Nerve transmission Muscle contraction Blood pressure regulation Regulation of hormones and neurotransmitters RDAs for Adults Adequate Intake (AI) 1000 mg/day, 1200 mg/day over age 51 The adequate intake is estimated as the amount needed for maximum retention. 4 5 Deficiency Osteoporosis in adults, rickets in children Low blood levels indicate parathyroid hormone deficiency, not calcium deficiency. Low blood levels – tetany (muscle spasms) Toxicity High supplemental doses may cause constipation. High supplemental doses may interfere with absorption of other minerals. High doses may also cause soft tissue and blood vessel calcification. May also cause kidney stones (open to question) UL for adults 2500 mg/day Good Food Sources Dairy, sardines with bones. Modest amounts in greens, nuts Supplement Forms Citrate, malate, aspartate, ascorbate, carbonate, gluconate, dolomite 6 PHOSPHORUS Second most abundant mineral in body after calcium 85% found as calcium phosphate (hydroxyapatite) crystals in bones and teeth. Absorption and Metabolism Easily absorbed in the small intestine, independent of amount in diet. Excess is excreted by the kidneys. Blood levels not as strictly controlled as that of calcium. High blood levels of phosphorus reduce the synthesis of the active form of vitamin D, reducing blood levels of calcium. This indirectly stimulates parathyroid hormone, increasing phosphorus excretion and increasing calcium retention by the kidney. PTH also increases calcium release from bone. Low blood levels of phosphorus increase the synthesis of the active form of Vitamin D. Vitamin D increases absorption of both calcium and phosphorus from the intestines 7 Functions Structure of bones and teeth as hydroxyapatite crystals. Major constituent of RNA and DNA Component of phospholipids (which are part of cell membranes) Required by every cell Component of ATP, the major energy compound used in body. Component of CP, or creatine phosphate, see exercise section. Activates or deactivates many enzymes in the body Phosphate buffering system regulates pH in cell cytoplasm RDAs for Adults 700 mg/day 8 Deficiency Rare because phosphorus is widespread in foods Aluminum in antacids can cause loss of phosphorus Deficiency causes low blood levels, effects are muscle weakness, bone loss, loss of appetite, anemia. Toxicity Bone resorption (mineral loss) in extremely high doses. Deposits of calcium phosphate crystals in soft tissue. In the form of phytates, in whole grains, may impede mineral absorption. Good Food Sources Meat and dairy richest sources. Phosphorus from phytates in grains are only partially absorbed. 9 MAGNESIUM About 60% is found in bone, 25% in muscle cells (mainly in the mitochondria), remainder in soft tissues and extracellular fluids. Absorption and Metabolism About 50% of dietary magnesium is absorbed. Absorbed in the blood bound to transport protein, eventually ionized into cations. Calcium competes somewhat for absorption. Functions Cofactor for over 300 enzymes Helps bind calcium to tooth enamel and bones Transmission of nerve impulses Relaxes muscles, including smooth muscles in the arteries Blood pressure regulation, associated with lower BP Regulates heart rhythm Stabilizes the ATP molecule Involved with functions of parathyroid hormone and vitamin D 10 RDAs for Adults Males – 420 mg/day Females – 320 mg/day Pregnant/Lactating – 350 mg/day Deficiency Nausea, muscle weakness, cramping, irritability, high blood pressure, abnormal heart rhythms, anxiety. Low magnesium has been linked to osteoporosis. Common in alcoholics. Toxicity High supplemental doses may cause diarrhea UL for supplementation – 350 mg/day Good Food Sources Spinach, kale, broccoli, beans, seeds, almonds, and cashews. 11 SULFUR Sulfur is supplied in the diet mainly through sulfur containing amino acids methionine and cysteine. Sulfur containing amino acids stabilizes protein structures, such as the rigid proteins in skin, hair and nails. Cysteine is part of glutathione – a major antioxidant synthesized the body. Good Food Sources Methionine and cysteine – Eggs and meat Sulfur is also found in: The vitamins thiamin and biotin Cruciferous vegetables such as cabbage and broccoli Onions and garlic Plant sources will be discussed in Outline 12 No RDA