Magnesium, an ignored mineral for healthy bones
In a study, researchers measured intake, absorption and excretion of magnesium in 4 - 8 year old children. Surprisingly, the researchers found that intake and absorption of magnesium, but not of calcium were significantly associated with bone density and bone mineral content.
When talking about healthy bones most often the mineral calcium is recommended, whereas magnesium is rarely mentioned. When it comes to children the relationship between magnesium and children's bones are mentioned even more rarely in spite of the fact that we know magnesium to be a key factor for healthy bones.
On that basis, Dr. Steven Abrams and his colleagues from various U.S. institutions specializing in agricultural research and nutrition for children, decided to investigate this matter. The study included 28 girls and 22 boys. The researchers used a dual-tracer stable isotrope technique in order to measure magnesium absorption.
Girls more vulnerable to shortages
The researchers discovered among other things that boys absorb and utilize magnesium slightly better than girls, although they found that the children's net retention of magnesium in the body did not differ. In addition, they found that small children's magnesium intake was significantly associated with BMC and BMD, but calcium intake were not.
- BMC (Bone Mineral Content): The total content of minerals in grams
- BMD (Bone Mineral Density): The amount of minerals in relation to the area determined in grams per square centimeter
Older children most at risk
The study showed that most, but not all American children aged 4 - 8 years received sufficient magnesium. However, it is not a period where they grow the most. In puberty the children's magnesium needs increases, and as a large part of our magnesium comes from whole grain products, vegetables, fruits, nuts and dairy products that teenagers do not consume nearly as much as the younger kids, they easily become deficient in magnesium.
If the body lacks magnesium the function of the parathyroid hormones is reduced, which means that the bones lose their mineral content and magnesium is released from bone tissue into the blood. If the body on the other hand gets too much magnesium the excess magnesium is excreted through the kidneys, as with calcium. In the blood the magnesium content is regulated in a narrow range for the sake of the cardiac function and regulation of the parathyroid hormones. A symptom of too much magnesium is loose bowels as magnesium in the gut attracts liquid.
A 2006 study on girls between 8-14 year looked at the effect of magnesium supplementation on bone mineral content. It showed that hip BMC was clearly increased in the group receiving supplements compared with the control group.
The year before, a group of researchers conducted a study with 52 eight year old children, 25 boys and 27 girls, which showed that the main factors associated with the children's BMD was the amount of protein and magnesium.
Here it is important to keep in mind that there are many different nutrients involved in bone development and maintenance. The challenge is not to forget any of them, although we focus on a few. In addition to nutrients, individual genetic factors are probably also involved.
Dr. Steven Abrams and his colleagues have shown that children's calcium intake, when not severely deficient, is only inconclusively linked to their BMC. On the other hand, they write that magnesium should get more consideration when it comes to healthy bones.
Abrams SA, et al. Magnesium metabolism in 4-year-old to 8-year-old children. J Bone Miner Res. 2014;29(1):118-22.
Baylor College of Medicine News - jul 9, 2013
Carpenter TO, et al. A randomized controlled study of effects of dietary magnesium oxide supplementation on bone mineral content in healthy girls. J Clin Endocrinol Metab. 2006;91(12):4866-72.
Bounds W, et al. The relationship of dietary and lifestyle factors to bone mineral indexes in children. J Am Diet Assoc. 2005;105(5):735-41.
Out of the body's total magnesium content of 24 grams, about half is found in the bones. The other half is found in the muscles and in the body's soft tissues. Magnesium is also important for many of the body's enzyme functions. In Denmark the recommended daily allowance of magnesium for children from 1-10 years is 85 mg and for adults 375 mg.