Magnesium is an important mineral that helps improve stamina, endurance, vitality, and energy levels. Magnesium is involved in several hundred enzymatic reactions, being required for cardiovascular function and the conversion of carbohydrates, proteins and fats to energy. It also functions in muscle relaxation and contraction, nerve transmissions, and the removal of excess toxic substances from the body. Magnesium is one of the most abundant minerals in the soft tissues.

Magnesium is the "iron" of the plant world - as iron is to hemoglobin, so magnesium is to chlorophyll, the "blood" pigment of plants. The central atom of the chlorophyll structure is magnesium. About 65% of our magnesium is contained in the bones and teeth. As with calcium, the bones act as a reservoir for magnesium in times of need. Elsewhere, most of it, like potassium, is found inside the cells. Usually, about 40-50% of the magnesium we consume is absorbed, though this may vary from 25-75% depending on stomach acid levels, body needs, type of magnesium, and dietary habits. The kidneys can excrete or conserve magnesium according to body needs. The intestines can also eliminate excess magnesium in the feces.

Magnesium has many essential metabolic functions in the body. It is important in the production and transfer of energy, in muscle contraction and relaxation, in nerve conduction, in protein synthesis, and in many biochemical reactions as a cofactor to enzymes. Magnesium also dilates blood vessels.

Sources
Almost all dietary magnesium come from the vegetable kingdom, though seafood has fairly high amounts. As a component of chlorophyll, the dark green vegetables are good sources. Beet leaves are an excellent source; most nuts, seeds and legumes have high amounts of magnesium; soy products, especially soy flour and tofu, and nuts such as almonds, pecans, cashews, and brazils are good examples. The whole grains, particularly wheat (especially the bran and germ), millet, and brown rice, and fruits such as avocado and dried apricot are other sources. Hard water can also be a valuable source of magnesium.

Requirements and Dosages
The current RDA is about 350mg for men and 300mg for women, increasing to about 450mg during pregnancy and lactation. Many authorities feel that the RDA should be doubled, to about 600-700mg. An average diet usually supplies about 120mg of magnesium per 1,000 calories, resulting in an estimated daily intake of about 250mg. Unless absorption is great, that is not going to produce adequate tissue levels of magnesium for most people. If you develop muscle cramps when taking magnesium, you may need to increase your level of calcium.

The calcium-magnesium balance is important. Magnesium and calcium have similar functions and can either encourage or antagonize each other. The role of these two minerals in muscle contraction is complementary: calcium stimulates muscles and magnesium relaxes them. Our body needs twice as much calcium as magnesium. Consumption of excessive amounts of magnesium inhibits bone formation, whereas excessive consumption of calcium produces symptoms that resemble magnesium deficiency.

To function optimally, magnesium must be balanced in the body with calcium, phosphorus, potassium, and sodium chloride. If calcium intake is increased, magnesium should be increased also. Your doctor may alter this ratio, increasing your level of magnesium for a period of time. Toxicity due to magnesium overload is almost unknown in a nutritional context, as excesses are usually eliminated in the urine and feces. However, symptoms of magnesium toxicity are more likely if calcium intake is low.

The levels of magnesium used by nutritional physicians are commonly in the range of 600-1,000mg. Some calcium-magnesium combinations are formulated with hydrochloric acid and vitamin D to aid mineral absorption. Taking them before bedtime may be very helpful in increasing utilization of both these important minerals and lead to better sleep.

Magnesium chelated with amino acids is probably the most absorbable form. Less absorbable forms include magnesium bicarbonate, magnesium oxide, and magnesium carbonate. Magnesium oxide is probably somewhat better than magnesium carbonate (dolomite). The newly available salts of magnesium aspartate or citrate, both known as mineral transporters, have a better percentage absorption.

When to take Calcium and Magnesium
There are conflicting recommendations about the best way to take calcium supplements. The National Institutes of Health (NIH) consensus statement on optimal calcium intake recommends taking no more than 200mg doses, between meals. The recently published clinical guidelines for the prevention and treatment of osteoporosis from the American Association of Clinical Endocrinologists suggest taking supplemental calcium with meals and with a bedtime snack. The decision to take the supplements with or between meals may be based on the type of supplement you're taking. Calcium and magnesium carbonate or hydroxide is more difficult to absorb on an empty stomach or in conditions where there is limited stomach acid. Therefore, absorption may be improved when it's taken with food, especially acidic foods such as citrus juice or fruit. Calcium and magnesium can act as acid neutralizers.

The citrate form is better absorbed on an empty stomach because it does not require gastric acid for absorption. It is the preferred supplement for those lacking stomach acid, including older people, those who have had stomach surgery and those taking medications that block gastric acid production.

The type and amount of calcium and magnesium you take as a supplement should be based on your medical history and your average dietary intake of calcium. Supplements should be taken in smaller doses throughout the day if convenient. If you take an iron supplement, don't take it at the same time as your calcium or magnesium supplement if they are in an antacid form.

One magnesium product that seems to work very well for some people is called Natural Calm. It comes in powder form and you add water (hot or cold) to make a drink.