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Anatomy and Physiology
Anatomy and Physiology is a dynamic textbook for the two-semester human anatomy and physiology course for life science and allied health majors. The book is organized by body system and covers standard scope and sequence requirements.
More InfoHuman Nutrition
This textbook serves as an introduction to nutrition. The book covers basic concepts in human nutrition, key information about essential nutrients, basic nutritional assessment, and nutrition across the lifespan.
More InfoPrinciples of Nutrition
A great textbook to get started on a journey into the world of health and nutrition. The first focus will be to demonstrate that nutritional science is an evolving field of study, continually being updated and supported by research, studies, and trials.
More InfoMicrobiology
Microbiology covers the scope and sequence requirements for a single-semester microbiology course for non-majors. The book presents the core concepts of microbiology with a focus on applications for careers in allied health. The pedagogical features of the text make the material interesting and accessible while maintaining the career-application focus and scientific rigor inherent in the subject matter.
More InfoChemistry
Chemistry 2e is designed to meet the scope and sequence requirements of the two-semester general chemistry course. The textbook provides an important opportunity for students to learn the core concepts of chemistry and understand how those concepts apply to their lives and the world around them. The book also includes a number of innovative features, including interactive exercises and real-world applications.
More InfoBiology
Biology 2e is designed to cover the scope and sequence requirements of a typical two-semester biology course for science majors. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology includes rich features that engage students in scientific inquiry, highlight careers in the biological sciences, and offer everyday applications.
More InfoMagnesium
Normal Range of 0.66-1.07mmol/L
| A Summary | Recommended Intakes for adults | Major functions | Deficiency diseases and symptoms | Groups at risk for deficiency | Toxicity | UL |
| Whole grains and legumes, almonds, cashews, hazelnuts, beets, collards, and kelp | 470mg/day | Component of mineralized bone, ATP synthesis and utilization, carbohydrate, lipid, protein, RNA, and DNA synthesis Structure of some vitamins and amino acids, acid-base balance |
Tremor, muscles pasms, loss of appetite, nausea None when |
Alcoholics, individuals with kidney and gastrointestinal disease | Nausea, vomiting, low blood pressure | 350mg/day |
Magnesium
Magnesium, an abundant mineral in the body, is naturally present in many foods, added to other food products, available as a dietary supplement, and present in some medicines (such as antacids and laxatives). Minerals in food are in organic compounds that work with other nutrients to ensure the body functions properly. Mineral scan not be made in the body; they come from the diet. The amount of minerals in the body is small—only 4 percent of the total body mass—and most of that consists of the minerals that the body requires in moderate quantities: potassium, sodium, calcium, phosphorus, magnesium, and chloride.
The organic molecule is part of the “living cells” group. The most abundant element in cells is hydrogen (H), followed by carbon (C), oxygen (O), nitrogen (N), phosphorous (P), and sulfur (S). We call these elements macro nutrients, and they account for about 99% of the dry weight of cells. Some elements, such as sodium (Na), potassium (K), magnesium (Mg), zinc (Zn), iron (Fe), calcium (Ca), molybdenum (Mo), copper (Cu), cobalt (Co), manganese (Mn), orvanadium (Va), are required by some cells in very small amounts and are called micro nutrients or trace elements.
All of these elements are essential to the function of many biochemical reactions, and, therefore, are essential to life. Magnesium’s position in the periodic table (group2) tells us that it is a metal. Metals form positive ions (cations).
A magnesium atom must lose two electrons to have the same number electrons as an atom of the previous noble gas, neon. Thus, amagnesium atom will form acation with two fewer electrons than protons and a charge of 2+. The symbol for the ion is Mg2+, and it is called a magnesium ion.
| Atomic Number, Z | Name | Atomic Mass Number, A | Symbol | Atomic Mass(u) | Percent Abundance or Decay Mode | Half-life, t1/2 |
| 12 | Magnesium | 24 | 24MG | 23.985042 | 78.99% | — |
Isotopes
Magnesium exists as a mixture of three isotopes, each with an atomic number of 12 and with mass numbers of 24, 25, and 26, respectively. These isotopes can be identified as 24Mg, 25Mg, and 26Mg. These isotope symbols are read as “element, mass number” and can be symbolized consistent with this reading.
For instance, 24Mgisreadas “magnesium 24,” and can be written as “magnesium-24” or “Mg-24.” 25Mgisreadas “magnesium 25,” and can be written as “magnesium-25” or “Mg-25.” All magnesium atoms have12 protons in their nucleus. They differ only because a 24Mg atom has 12 neutrons in its nucleus, a25 Mg atom has13 neutrons, and a 26Mg has 14 neutrons.
Soaps often form films that are difficult to rinse away, especially in hard water, which contains high concentrations of calcium and magnesium mineral salts. Detergents contain synthetic surfactant molecules with both polar and non polar regions that have strong cleansing activity but are more soluble, even in hard water, and, therefore, leave behind no soapy deposits.
An ionic detergents, such as those used for laundry, have a negatively charged anion at one end attached to a long hydrophobic chain, where as cationic detergents have a positively charged cation instead.
The symbol for an atom indicates the element via its usual two-letter symbol, the mass number as a left superscript, the atomic number as a left subscript(sometimes omitted), and the charge as aright superscript.
A sample of magnesium is found to contain 78.70% of 24Mgatoms (mass23.98amu), 10.13% of 25Mgatoms (mass 24.99 amu), and 11.17 % of 26 Mgatoms (mass 25.98 amu). Calculate the average mass of a Mg atom.
Answer: 24.31 amu
Magnesium is also important for energy production, oxidative phosphorylation, glycolysis, synthesis of DNA, RNA, and the antioxidant glutathione.
Magnesium is essentiallya required helper molecule. Many enzymes do not work optimally, or even at all, unless bound to other specific non-protein helper molecules.
They may bond either temporarily through ionic or hydrogen bonds, or permanently through stronger covalent bonds. Binding to these molecules promotes optimal shape and function of their respective enzymes.
Magnesium acts is as a cofactor in more than 300 enzymatic reactions required for a diverse set of bodily functions, including –
- Protein synthesis,
- Muscle and nerve function(active transport of calcium and potassium ions across cell membranes)
- Blood glucose control
- Blood pressure regulation
| Function | Deficiencies Can Lead To | Sources |
| Required co factor for ATP formation; bone formation; normal membrane functions; muscle function | Mood disturbances, Muscles pasms | Whole grains, leafy green vegetables |
Ion channel-linked receptors
Bind a ligand and open a channel through the membrane that allows specific ion stop ass through. To form a channel, this type of cell-surface receptor has an extensive membrane-spanning region. When a ligand binds to the extra cellular region of the channel, there is a conformational change in the protein’s structure that allows ions such as sodium, calcium, magnesium, and hydrogen to pass through (Figure below).
Magnesium and the Skeleton System
Approximately 60 percent of magnesium in the human body is stored in the skeleton, making up about 1 percent of mineralized bone tissue. Magnesium is not an integral part of the hard mineral crystals, but it does reside on the surface of the crystal and helps maximize bone structure also playing a role in the processes of osteo clasts and osteo blasts Observational studies link magnesium deficiency with an increased risk for osteoporosis.
Magnesium also impacts the levels of both parathyroid hormone and the active form of vitamin D, which are major regulators of bone homeostasis.
Other Nutrients
The minerals magnesium and fluoride may also play a role in supporting bone health. While magnesium is only found in trace amounts in the human body, more than 60 percent of it is in the skeleton, suggesting it plays a role in the structure of bone.
Nutrients and Bone Health
| Nutrient | Role in bone health |
| Magnesium | Structural component of bone |
Bioavailability is defined by to how easily a substance is absorbed by the body and references the amount absorbed for cellular uptake, usage and storage.
The majority of magnesium is absorbed in the small intestine, via a saturable transport system and a passive diffusion through bulk flow of water.
The absorption is dependent on the quantity of magnesium consumed as magnesium will be less rapidly absorbed if levels are adequate and excreted through the urine or stools if given in excess compared to inadequate levels.
The amount utilised by the tissues based on the osmolality of the magnesium source is and the amount of elemental magnesium released. Well-dissolved forms (in liquid) absorb completely in the gut compared to less soluble forms.
Organic magnesium salts are, in general, more soluble than inorganic magnesium salt.
Normal serum magnesium concentrations range between 0.75 and 0.95 millimoles (mmol)/L
As the majority of magnesium is located inside the bone or cells, assessing the status can be difficult and therefore measuring serum magnesium concentration is commonly used, despite the fact even serum levels have little correlation with total body magnesium levels or concentrations in specific tissues.
As some experts are not keen on the accuracy of the serum testing, other methods for assessing magnesium status can be used from obtain sample in erythrocytes, saliva, urine; measuring ionized magnesium concentrations in blood, plasma, or serum; and conducting a magnesium-loading test, also known as a tolerance test.
Furthermore, for a comprehensive evaluation of magnesium status, both laboratory tests and a clinical assessment might be required.
Dietary Reference Intake of Magnesium
The RDAs for magnesium for adults between ages nineteen and thirty are 400 milligrams per day for males and 310 milligrams per day for females. For adults above age thirty, the RDA increases slightly to 420 milligrams per day for males and 320 milligrams for females.
Source:
Dietary Supplement Fact Sheet:Magnesium. National Institutes of Health, Office of Dietary Supplements.
http://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
Updated July13,2009.
Accessed November12,2017.
Remember that RDA’s vary by country,
by year of publication.
Table 1 : Dietary Reference Intakes for Magnesium
| Age Group | RDA(mg/day) | UL from non food sources (mg/day) |
| Infants(0–6months) | 30* | – |
| Infants(6–12months) | 75* | – |
| Children(1–3years) | 80 | 65 |
| Children(4–8years) | 130 | 110 |
| Children(9–13years) | 240 | 350 |
| Adolescents(14–18years) | 410 | 350 |
| Adults(19–30years) | 400 | 350 |
| Adults(>30years) | 420 | 350 |
*denotes Adequate Intake
Magnesium Deficiency
Magnesium deficiency is also known as hypomagnesemia and is defined as a serum magnesium level less than 0.75 mmol/L .As the kidney largely controls magnesium homeostasis, it excretes approximately 120 mg magnesium via urination daily. Low levels of magnesium will result in a reduction of urinary excretion.
With in the nephron the blood comes in intimate contact with the waste-collecting tubulesina structure called The glomerulus. Water and many solutes present in the blood, such as magnesium, but also ions of sodium, calcium and others. Signs and symptoms of severe magnesium efficiency may include tremor, musclespasms, loss of appetite, and nausea.
Some observational studies suggest mild magnesium deficiency is linked to increased risk for car diovascular disease and that people who have more magnesium in their diets have a lower risk of some types of heart disease and stroke. There is also indication that people with higher levels of magnesium are less likely to develop type 2 diabetes due the role in blood glucose regulation. However, both these areas need further research.
A magnesium-deficient diet is associated with decreased levels Of parathy roidhorm one and the activation of vitaminD, which may lead to an impairment of bonere modeling. A study of nine hundred elderly women and men did show that higher dietary intakes of magnesium correlated toan increased bone mass density (BMD) inthehip. Only a few clinical trial shave valuated the effects of magnesium supplement son bone health and their results suggests omemodest benefit son BMD.
Magnesium in the nephron and location
| Substance | PCT | Loop of Henle |
| Magnesium | Reabsorbed; diffusion | Reabsorbed in thick ascending limb |
Magnesium
| Sources | Recommended daily allowance | Function | Problems associated with deficiency |
| Whole grains, nuts, leafy green vegetables | 310–420 mg | Enzyme activation, production of energy, regulation of other nutrients | Agitation, anxiety, sleep problems, nausea and vomiting, abnormal heart rhythms, low blood pressure, muscular problems |
Magnesium deficiency in the blood and other tissues can also be linked to migraines headaches. There have been studies indicating magnesium supplementation as a therapeutic treatment for migraine headaches; however, any commencement must be discussed with a health care specialist.
Furthermore, more research is needed in magnesium supplementation for the management of migraine symptoms.
Magnesium is part of the green pigment, chlorophyll, which is vital for photosynthesis in plants; therefore green leafy vegetables are a good dietary source for magnesium. Magnesium is also found in high concentrations in fish, dairy products, meats, whole grains, and nuts.
Additionally chocolate, coffee, and hard water contain a good amount of magnesium. Most people in America do not fulfill the RDA for magnesium in their diets. Typically, Western diets lean toward a low fish in take and the unbalanced consumption of refined grains versus whole grains.
Table 2: Magnesium Content of Various Foods
| Food | Serving | Magnesium(mg) | Percent Daily Value |
| Almonds | 1oz. | 80 | 20 |
| Cashews | 1oz. | 74 | 19 |
| Soymilk | 1c. | 61 | 15 |
| Black beans | ½c. | 60 | 15 |
| Edamame | ½c. | 50 | 13 |
| Bread | 2slices | 46 | 12 |
| Avocado | 1c. | 44 | 11 |
| Brown rice | ½c. | 42 | 11 |
| Yogurt | 8oz. | 42 | 11 |
| Oatmeal, instant | 1packet | 36 | 9 |
| Salmon | 3oz. | 26 | 7 |
| Chicken breasts | 3oz. | 22 | 6 |
| Apple | 1 medium | 9 | 2 |
Magnesium. National Institutes of Health, Office of Dietary Supplements.
http://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
Updated July13,2009. | Accessed November12,2017.
Absorption of magnesium can be enhanced by:
-
- Reducing or avoiding calcium – rich foods-Calcium is used as an antagonist in treating severe hyper magnesaemia. There is some indication that reducing or avoiding calcium rich sources two hours pre or post prandial increases the absorption of magnesium. However, any practice must be discussed with a health care advisor as calcium is an important nutrient for normal functioning and should not be completely avoided.
-
- Avoiding high-dose zinc supplements – There is some induction that very high doses of zinc from supplements (142 mg/day) can interfere with magnesium absorption and disrupt the magnesium balance in the body.
-
- Treating vitamin D deficiency – Magnesium is a cofactor for vitamin D synthesis, and activated vitamin D. Furthermore, vitamin D canincrease intestinal absorption of magnesium and, forming a feed-forward loop to maintain its homeostasis.
-
- Eating raw vegetables – When most vegetables are cooked, the nutritional value is lowered.
-
- Limiting Colas and drinks high in phosphates – High phosphate beverages can lower the absorption of magnesium.
-
- Limiting high fat foods – Foods high in fat prevent magnesium form being absorbed in the intestines.
- Limiting alcohol intake – Alcohol eliminates increases magnesium excretion via the kidneys.
Magnesium supplements are available in a variety of forms, including Magnesium oxide, Citrate, and Chloride. The absorption will vary and soluble forms are completely absorbed than less soluble ones.
A small amount of studies conclude magnesium in the aspartate, citrate, lactate, and chloride forms is absorbed more completely and is more bio available than magnesium oxide and magnesium sulphate.
Magnesium Toxicity
Excess intakes of magnesium from food sources do not cause harmful effects in healthy people due to excess being removed via urination. However, high doses of magnesium from supplementation or medications often proves to be symptomatic, including diarrhoea, nausea and abdominal cramping.
Magnesium toxicity, also known as hyper magnesaemia occurs from very large doses of magnesium-containing laxatives and antacids taken in amounts of 5,000 mg/day, which can be fatal in vulnerable population groups, such as very young children and the elderly. Serum concentrations exceed 1.74–2.61 mmol/L and symptoms include hypotension, nausea, vomiting, facial flushing, retention of urine, ileus, depression, and lethargy before progressing to muscle weakness, difficulty breathing, extreme hypotension, irregular heartbeat, and cardiac arrest.
The risk of magnesium toxicity is higher with those with an impaired renal function because the inability to remove excess magnesium.
Mild to moderate hyper magnesaemia is treated by a cessation of magnesium therapy, which mainly includes supplementation or medication as dietary sources rarely cause hyper magnesaemia.
Severe and symptomatic hyper magnesaemia, includes lowering serum magnesium should be lowered, as calcium antagonises the toxic effects of magnesium, it is usually administered intravenously. This Administration of glucose and insulin may also help to promote increase cellular uptake.
Direct Foods high in magnesium
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Direct -Foods low in magnesium
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Modulation to increase
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Possible modulation to decrease absorption: Calcium and Zinc rich foods
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Amazing One hour audio recording with Jean-David Tremblay, Naturopath, along with additional information on Magnesium :
https://aqtn.ca/magnesium/
