Eating a wide variety of legumes, nuts, whole grains, and vegetables are good sources of magnesium.
Absorption: From the upper part of the small intestine. Mg ions are absorbed with great difficulty. It forms insoluble phosphate like calcium. Hence the principles that apply for Ca absorption are also applicable for Mg.
1. Blood – whole blood 3 mgm, plasma 2.5 mgm, corpuscles 3.5 mgm per 100 ml. Distribution of Ca and Mg in blood is generally opposite. Calcium remains almost wholly in plasma and very little in the cells, while Mg is mostly found in the cells and less in plasma.
2. Bones – 70% of the Mg of the body is present in the bones as phosphates.
3.Voluntary muscles – about 0.02% (Ca – 0.007%).
4. Chlorophyll – it is the green pigment of plants. It is a porphyrin derivative of magnesium.
Excretion: in urine, 0.1-0.2 gm in 24hours. It is generally not excreted through the large gut. Mg content of faeces largely represents unabsorbed Mg. of diet. Metabolism of Mg is probably controlled by adrenal cortex directly or indirectly.
Benefits of Magnesium
- Forms bone of tooth.
- Activates of enzymes Mg ions activate the enzyme phosphates. It accelerates the action of bone phosphates.
- Takes part in the chemistry of muscular contraction – Mg is a member of a complex coenzymes system takes part in the chemical changes under lying muscular contraction. It may be that here it also helps the action of muscle phosphates.
- Antagonistic to calcium ion – The distribution and function of Mg ion is generally antagonistic to calcium ion.
In man vascular disturbances, hyperexcitability, convulsions and ultimately death. Something tetany develops and is known as Mg-tetany. If Ca intake is increased the effect of Mg deficiency becomes very severe.
Chronic or excessive vomiting and diarrhea may also result in magnesium depletion
Healthy kidneys are able to limit urinary excretion of magnesium to compensate for low dietary intake. However, excessive loss of magnesium in urine can be a side effect of some medications and can also occur in cases of poorly controlled diabetes and alcohol abuse
Early signs of magnesium deficiency include loss of appetite, nausea, vomiting, fatigue, and weakness. As magnesium deficiency worsens, numbness, tingling, muscle contractions and cramps, seizures, personality changes, abnormal heart rhythms, and coronary spasms can occur Severe magnesium deficiency can result in low levels of calcium in the blood (hypocalcaemia). Magnesium deficiency is also associated with low levels of potassium in the blood (hypokalemia).
Many of these symptoms are general and can result from a variety of medical conditions other than magnesium deficiency. It is important that a physician should evaluate health complaints and problems so that appropriate care can be given.
Who need more?
Some medicines may result in magnesium deficiency, such as diuretics, antibiotics, and medications used to treat cancer. Therefore people on such drugs need extra magnesium.
Individuals with poorly controlled diabetes may benefit from magnesium supplements because of increased magnesium loss in urine associated with hyperglycemia.
Magnesium supplementation may be indicated for persons with alcoholism. Low blood levels of magnesium occur in 30% to 60% of alcoholics, and in nearly 90% of patients experiencing alcohol withdrawal
Individuals with chronic malabsorptive problems such as Crohn’s disease, gluten sensitive enteropathy, regional enteritis, and intestinal surgery may lose magnesium through diarrhea and fat malabsorption. Individuals with these conditions may need supplemental magnesium.
Individuals with chronically low blood levels of potassium and calcium may have an underlying problem with magnesium deficiency. Magnesium supplements may help correct the potassium and calcium deficiencies.
Older adults are at increased risk for magnesium deficiency. Seniors are also more likely to be taking drugs that interact with magnesium. This combination of factors places older adults at risk for magnesium deficiency. It is very important for older adults to consume recommended amounts of dietary magnesium.
Symptoms of high intake
Dietary magnesium is not harmful for the health, however pharmacologic doses of magnesium in supplements can promote adverse effects such as diarrhea and abdominal cramping. Risk of magnesium toxicity increases with kidney failure, when the kidney loses the ability to remove excess magnesium. Very large doses of magnesium-containing laxatives and antacids also have been associated with magnesium toxicity.
Signs of excess magnesium can be similar to magnesium deficiency and include changes in mental status, nausea, diarrhea, appetite loss, muscle weakness, difficulty breathing, extremely low blood pressure, and irregular heart beat.
Not definitely known. Its presence in normal diet is generally enough for its requirement in the body. Recent recommendation is 350 mgm per day for adult males and 300 mgm per day for adult females.