Calcium & Magnesium Side Effects

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A woman is drinking a glass of milk. (Image: Christopher Robbins/Photodisc/Getty Images)

Calcium and magnesium play a key role in the development and maintenance of bones, along with other essential functions. Together, these minerals share a relationship that is complementary and, under certain conditions, competing. Understanding their side effects is useful in understanding how you can use these minerals individually and collectively to optimize the functions and overall condition of your body.

Calcium and Magnesium: A Balancing Act

Magnesium is needed to metabolize calcium, so it must be present in your body in adequate amounts. Given this mutually dependent relationship, it is key to have an appropriate ratio of both minerals for them to be effective. If your calcium intake is high, your magnesium intake needs to be adjusted proportionately. The recommended daily allowance for calcium and magnesium indicate a ratio ranging from approximately 2.5-to-1 to 4-to-1 calcium to magnesium, depending upon one’s age and sex.

Recommended Daily Allowances Calcium and Magnesium

As of 2014, the recommended daily allowance, or RDA, for magnesium is as 255 to 265 milligrams for women, and 330 to 350 milligrams for men. The RDA for calcium is 800 milligrams for women up through 50 years of age, and 1,000 milligrams for women over 50. Calcium RDA for min is 800 milligrams. These recommendations are set by the Food and Nutrition Board of the Institute of Medicine. Note that you do not need to take magnesium and calcium in the same supplement for your body to absorb calcium. The minerals, though, must each be present in the body in adequate amounts in order for you to use the calcium.

Side Effects: Too Little, Too Much Calcium

According to the National Institutes of Health, a consistent deficiency of calcium over time may lead to osteoporosis, resulting in brittle or porous bones, or osteomalacia, resulting in soft bones. In children, osteomalacia is referred to as rickets. Conversely, too much calcium in the blood, a condition called hypercalcemia, may negatively impact kidney functions. Symptoms of hypercalcemia include a feeling of numbness/tingling in the fingers, convulsions, vomiting, constipation, cramping of the muscles, an abnormal heart rhythm, lethargy, poor appetite, persistent thirst and fatigue. According to the Linus Pauling Institute's Micronutrient Information Center, no incidences of hypercalcemia have been documented to occur from dietary intake, only from the intake of calcium supplements.

Side Effects: Too Little, Too Much Magnesium

While rare, according to the National Institutes of Health, a severe magnesium deficiency may result in decreased appetite, nausea, vomiting, fatigue, muscle spasms/tremors and personality changes. A severe magnesium deficiency may also result in low levels of calcium in the blood, a condition called hypocalcemia, as well as low levels of potassium in the blood, a condition called hypokalemia. At the other extreme, the first sign of too much magnesium in the system is diarrhea. Progressive signs of excessive magnesium include changes in mental state, notably confusion; nausea; appetite loss; weakness; difficulty breathing; abdominal cramping; reduced blood pressure, a condition known as hypotension; and an abnormal heart rhythm. Similar to calcium, excessive magnesium is not caused by dietary intake, but from the intake of supplemental magnesium, including laxatives and antacids that contain magnesium.


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