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How Magnesium Can Affect Bone Mineral Density

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Half of the body’s magnesium store is found in the bones and the mineral makes up 1% of the mineral content of the bone. In addition, recent studies have found that magnesium plays vital roles in maintaining a healthy bone mineral density. Magnesium is especially important when calcium supplementation is given to reduce bone fractures because magnesium helps the body absorb and utilize calcium. In fact, some researchers believe that magnesium is more important to bone health than calcium. Read on to find out just how important magnesium is to bone mass and bone strength and why it is highly recommended for postmenopausal women receiving calcium and estrogen combinations.

Magnesium and Magnesium Deficiency

Magnesium is an essential nutrient in the body. It is found in all living cells and it is required for the proper functioning of a long list of important enzymes as well as the chief energy molecule for cellular metabolism, ATP (adenosine triphosphate).

As the fourth most abundant mineral in the body, magnesium level is strictly regulated. While half of the total body magnesium level is found in cells, the other half is stored in the bones.

Only 1% of the body’s magnesium level can be found in the blood.

In humans, magnesium is needed for maintaining normal muscle and nerve functions, for supporting the immune system, for regulating heartbeat and for keeping the bones strong.

Food sources of magnesium include whole-grain brans and germs, almond, cashew, peanut, oatmeal, spinach, soybean, potato, brown rice, lentils, beans, banana, milk, yogurt, chocolate and halibut.

Recommended Dietary Intake of Magnesium
  • 0 – 6 months – 30 mg/day
  • 7 – 12 months – 75 mg/day
  • 1 – 3 years – 80 mg/day
  • 4 – 8 years – 130 mg/day
  • 9 – 13 years – 240 mg/day
  • Adults – 400 – 420 mg/day (male); 310 – 360 mg/day (female) and 350 – 400 mg/day (pregnant women)

Surveys show that more than 50% of the US population does not meet these daily recommended dietary intake values. Therefore, hypomagnesemia and magnesium deficiency are public health concerns.

Low magnesium levels can affect all the organs of the body. Symptoms of magnesium deficiency include muscle cramp, fatigue, dizziness and hyperexcitability. Magnesium deficiency is treated with oral magnesium supplements and/or eating more magnesium-rich foods.

However, in cases of severe deficiency, intravenous or intramuscular magnesium sulfate may be needed to quickly arrest the damage done to the body and restore normal magnesium levels.

Symptoms of severe magnesium deficiency include loss of appetite, nausea, vomiting, heart failure, tremor, muscle spasms, bone fractures, personality changes and neurological damage. If left untreated magnesium deficiency may lead to death.

Because magnesium is closely linked to other important minerals in the body, magnesium deficiency can lead to calcium deficiency and potassium deficiency as well as abnormally high sodium levels.

Magnesium and Bone Health

Considering the fact that the bone is the site of storage for half of the magnesium in the body, the mineral must be essential to the mineralization of the bone. And it is.

Magnesium as Bone Mineral

Even though calcium is widely believed to be the sole mineral content of the bone, the truth is there are at least a dozen minerals that make up the bone. One of these other minerals is magnesium.

The 50% of the body’s magnesium level stored in the bone makes up 1% of the mineral content of the bone.

You may think that 1% is a small fraction of the bone but the function of magnesium in the bone makes it more important to bone strength than bone mineral content. The chief influence of magnesium involves the nature of the bone matrix and also bone metabolism.

When magnesium is increasingly stripped away from the bone, bone crystals become larger, hollower and more brittle.

Studies have shown that women with osteoporosis usually have large bone crystals than women who do not have osteoporosis. Scientists believe that this is responsible for the increased brittleness of the bones of osteoporotic women.

Therefore, magnesium affects the microstructure of the bones and it is needed to prevent the deterioration of bone tissue. With low magnesium levels, the bone becomes fragile and the risk of fractures is significantly higher.

Magnesium as Calcium Regulator

Magnesium is involved in the absorption and metabolism of calcium. This is why low magnesium level causes hypocalcemia.

Magnesium raises blood calcium levels by improving its absorption. This is why most calcium supplements also contain magnesium. However, most supplements contain calcium in twice the amount of magnesium. Studies have shown that this may not the ideal ratio especially for bone health.

High blood calcium levels can actually prevent the absorption of magnesium. Multiple clinical studies have confirmed that a high blood calcium level is actually bad for health.

When calcium accumulates in the blood, it is readily deposited on the soft tissues of the body as well as the walls of the arteries. This causes calcification of tissues and organs and is also responsible for the increased risk of heart attack, stroke and kidney stones associated with high-dose calcium supplementation.

Ideally, your magnesium intake should rival or even be higher than your calcium intake.

Magnesium does not only increase blood calcium levels but also regulates its effect and helps move it to the bones where calcium is needed.

This is not only good for bone health and cardiovascular health but it has also been demonstrated to help reduce the risk of kidney stones by preventing the formation of calcium oxalate crystals in the kidneys.

Because the body only absorbs half of the calcium it gets from dietary sources and studies have shown that calcium-only supplementation is ineffective in the treatment of osteoporosis and bad for health, magnesium becomes a lot more important than calcium for improving bone mineral density and bone strength.

Magnesium as Hormone Sensitizer

One of the ways by which magnesium deficiency impairs calcium metabolism is by inhibiting the activity of the hormones that regulate calcium. These hormones include calcitriol (Vitamin D), parathyroid hormone and calcitonin.

Magnesium can make the body more sensitive to the effects of vitamin D. One of such effects of the vitamin is the utilization of calcium by the bones.

Vitamin D (along with vitamin K) is needed for proper mineralization of the body. Together, these vitamins stimulate the production of the protein, osteocalcin, from osteoblasts (the cells that produce the bone). Osteocalcin then binds calcium to the bone.

Therefore, vitamin D should be combined with calcium to improve bone health. And magnesium makes this combination work.

In addition, calcitonin is also essential to the mineralization of the bone. This thyroid hormone removes calcium from the blood and soft tissues and returns the mineral back to the bone.

Magnesium enhances the activities of calcitonin and stimulates its release from the thyroid gland.

Lastly, magnesium is also involved in the secretion of parathyroid hormone. Studies show that low magnesium levels trigger the release of this hormone. However, very low magnesium level (such as the one seen during magnesium deficiency) paradoxically blocks the secretion of parathyroid hormone.

Although parathyroid hormone raises blood calcium levels by removing the mineral from bones (the opposite effect to calcitonin), it is also known to promote vitamin D production and regulate magnesium levels.

Is parathyroid hormone good or bad for bone health? All evidence points to the former.

Reduced sensitivity to parathyroid hormone is one of the presentations of osteoporosis. And studies show that magnesium improves parathyroid hormone activity, increases bone turnover and produces an overall increase in bone mass.

Magnesium as Alkalizing Agent

Magnesium is an alkalizing agent in the body. It can help restore the pH of the blood by neutralizing acidity.

In fact, magnesium-rich foods are commonly used in detoxification programs to help counter the harmful effects of acidifying foods and drugs.

The alkalizing effect of magnesium can also help bone mineral density by preventing the leaching away of calcium from the bones. When the acidity of the blood is raised, the body strips calcium from bones to help neutralize this acidity. Therefore, calcium removes the acidifying agent out of the body but this can easily lead to bone loss as the calcium used is also excreted.

Because magnesium is also an alkalizing agent, it can be sacrificed in place of calcium.

Therefore, by restoring the acid-base balance before the body turns to calcium, magnesium protects the bone and helps maintain bone mass.

A 1999 study published in The American Journal of Clinical Nutrition confirmed this effect.

In that study, the researchers took data from the famed Framingham Heart Study to correlate dietary magnesium (as well as potassium, fruits and vegetables) intake with bone mineral densities of the participants.

The researchers concluded that alkalizing agents such as magnesium (and potassium, fruits and vegetables) contributed to the maintenance of bone mineral density.

More Studies on Magnesium and Bone Health

Magnesium Deficiency and Osteoporosis

A 1999 study published in the journal, Magnesium Research, investigated the mechanisms by which magnesium deficiency affects bone health in rats.

The researchers induced magnesium deficiency in a group of rats while keeping another group on magnesium-rich diet. They measured the serum levels of magnesium, calcium, parathyroid hormone, and vitamin D at regular intervals during the 16-week duration of the study.

The mineral contents of the rat’s femurs were assessed early in the study and at the end.

The results showed that at the end of the 16-week, the rats fed on the magnesium-depleted diet had very low serum magnesium, parathyroid hormone and vitamin D levels but higher calcium levels than the control group.

In addition, the researchers found that magnesium deficiency disrupted the cycle of bone formation and bone resorption and, therefore, resulted in reduced bone volume and loss of bone mass.

A 2006 study published in the journal, Osteoporosis International, also investigated the effect of magnesium on bone health and found that bone mass was affected by low magnesium levels even before the animals became magnesium deficient.

The researchers found that lowering magnesium intake to 50% of the recommended dietary intake can significantly lower bone mineral content and reduce bone volume.

They attributed these changes to lowered vitamin D and parathyroid hormone levels as well as the increased production of inflammatory cytokines and substance P.

A 2009 study published in the Journal of the American College of Nutrition also reached the same conclusions.

The researchers found that these negative effects on the bone suggested that the rising incidence of osteoporosis may be due to long-term suboptimal magnesium intake. Therefore, although clear magnesium deficiency is rare, the risk of osteoporosis is still high in the population because most people never get the recommended daily dietary intake of magnesium.

Magnesium, Alcoholism, and Osteoporosis

A 1994 study published in the journal, Alcoholism: Clinical and Experimental Research, investigated the possibility of magnesium deficiency induced by alcoholism being responsible for the increased risk of osteoporosis among alcoholics.

The researchers identified that chronic alcoholism can contribute to magnesium deficiency by

  • reducing kidney functions and causing magnesium loss through impaired reabsorption of the mineral from the kidney tubules
  • low dietary magnesium intake through poor dietary choices
  • gastrointestinal loss of magnesium through vomiting and diarrhea
  • use of prescription drugs (aminoglycosides and diuretics) that remove magnesium from the body

All of these effects of alcoholism can reduce bone mass by causing chronic hypomagnesemia or clear magnesium deficiency.

Alcoholic osteoporosis is, however, not the only form of osteoporosis associated with low serum and bone magnesium levels.

A 1988 study published in the journal, Magnesium Research, also found large, abnormal bone crystals and low bone magnesium levels in people suffering from postmenopausal osteoporosis and osteoporosis in the elderly.

Magnesium and Postmenopausal Osteoporosis

The use of magnesium supplements in the treatment of osteoporosis in postmenopausal women is well studied.

One example of such studies was published in the journal, Nutrition Reviews, in 1995. At the end of the 2-year study, the researchers concluded that magnesium supplementation was effective at increasing bone mineral density and preventing fractures.

A 1991 study published in the Journal of Nutritional Medicine also came to this conclusion.

For this study, the researchers investigated the benefits of a magnesium-rich diet given to postmenopausal women receiving hormone replacement treatment for 6 – 12 months.

They found that magnesium not only increased bone mineral density and reduced fractures but that these positive effects persisted for 2 years after the magnesium intervention. The researchers, therefore, recommended the adoption of a magnesium-rich diet by women as early as the start of menopause in order to help prevent osteoporotic fractures.

A 1990 study published in the journal, Magnesium Research, identified an oversight in the hormone replacement treatment recommended for postmenopausal women.

The researchers discovered that the estrogen and calcium prescribed for the prevention and treatment of postmenopausal osteoporosis increased the body’s need for magnesium. Therefore, long-term use of both agents can lower magnesium levels and even cause magnesium deficiency.

Such outcome will defeat the purpose of calcium-estrogen therapy for improving bone health because magnesium is needed to move calcium from the blood to the bones.

The researchers also recognized the dangers of increasing the dose of calcium supplement without also raising the dose of magnesium. In their recommendation, they considered magnesium supplementation to be especially vital to a safe and effective calcium-estrogen combination therapy in postmenopausal osteoporosis treatment.

Lastly, a 1990 study published in The Journal of Reproductive Medicine reviewed past studies investigating calcium megadose supplementation in the treatment of postmenopausal osteoporosis.

The researchers found high-dose calcium to be ineffective for reducing the risk of osteoporotic fractures and also dangerous because it caused soft tissue calcification.

In their opinion, they believed magnesium to be the more important mineral for improving bone mass and reducing the risk of fractures in postmenopausal women.





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