Chapter 12. Micronutrients for Bones
Magnesium
Role of Magnesium
Approximately 60 percent of magnesium in the human body is stored in the skeleton, making up about 1 percent of mineralized bone tissue. Magnesium is not an integral part of the hard mineral crystals, but it does reside on the surface of the crystals and helps maximize the bone structure.
In addition to participating in bone maintenance, magnesium has several other functions in the body. In every reaction involving the cellular energy molecule, ATP, magnesium is required. More than three hundred enzymatic reactions require magnesium. Magnesium plays a role in protein synthesis and repair, the synthesis of DNA and RNA, carbohydrates, and lipids, and is essential for nerve conduction and muscle contraction. Another health benefit of magnesium is that it may decrease blood pressure. Finally, a higher magnesium intake is associated with a lower risk of colorectal cancer.
Dietary Reference Intake for Magnesium
The RDAs for magnesium for adults between ages nineteen and thirty are 400 milligrams per day for males and 310 milligrams per day for females. For adults above the age of thirty, the RDA increases slightly to 420 milligrams per day for males and 320 milligrams for females.
| Age Group | RDA (mg/day) | UL from non-food sources (mg/day) |
| Infants (0–6 months) | 30* | – |
| Infants (6–12 months) | 75* | – |
| Children (1–3 years) | 80 | 65 |
| Children (4–8 years) | 130 | 110 |
| Children (9–13 years) | 240 | 350 |
| Adolescent females (14–18 years) | 360 | 350 |
| Adolescent males (14–18 years) | 410 | 350 |
| Female adults (19–30 years) | 310 | 350 |
| Male adults (19–30 years) | 400 | 350 |
| Female adults (> 30 years) | 320 | 350 |
| Male adults (> 30 years) | 420 | 350 |
| * denotes Adequate Intake | ||
| Data Source: (“Dietary Reference Intakes,” 2006)[1] | ||
Dietary Sources of Magnesium
Magnesium is part of the green pigment, chlorophyll, which is vital for photosynthesis in plants; therefore, green leafy vegetables are a good dietary source of magnesium. Magnesium is also found in high concentrations in fish, dairy products, meats, whole grains, and nuts. Additionally, chocolate, coffee, and hard water contain a good amount of magnesium. Most people do not meet the RDA for magnesium in their diets. Typically, Western diets lean toward a low fish intake and the unbalanced consumption of refined grains versus whole grains.
| Food | Serving | Magnesium (mg) | Percent Daily Value |
| Almonds | 1 oz. | 80 | 20 |
| Cashews | 1 oz. | 74 | 19 |
| Soymilk | 1 c. | 61 | 15 |
| Black beans | ½ c. | 60 | 15 |
| Edamame | ½ c. | 50 | 13 |
| Bread | 2 slices | 46 | 12 |
| Avocado | 1 c. | 44 | 11 |
| Brown rice | ½ c. | 42 | 11 |
| Yogurt | 8 oz. | 42 | 11 |
| Oatmeal, instant | 1 packet | 36 | 9 |
| Salmon | 3 oz. | 26 | 7 |
| Chicken breasts | 3 oz. | 22 | 6 |
| Apple | 1 medium | 9 | 2 |
| Data Source: (“Magnesium,” 2009)[2] | |||
Consuming Too Little Magnesium
Low blood magnesium (hypomagnesemia) may result from chronic kidney disease, chronic diarrhea, or alcoholism and may play a role in low blood calcium.
Observational studies link magnesium deficiency with an increased risk of osteoporosis. A magnesium-deficient diet is associated with decreased levels of parathyroid hormone and the activation of vitamin D, which may lead to an impairment of bone remodeling. A study on nine hundred elderly women and men showed that higher dietary intakes of magnesium correlated to an increased bone mineral density in the hip.[3] Only a few clinical trials have evaluated the effects of magnesium supplements on bone health and their results suggest some modest benefits on bone mineral density.
Many Canadians do not get the recommended intake of magnesium from their diets. Some observational studies suggest mild magnesium deficiency is linked to an increased risk for cardiovascular disease. Signs and symptoms of severe magnesium deficiency may include tremor, muscle spasms, loss of appetite, cramps, irritability, weakness, and nausea.
- https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/dietary-reference-intakes/tables/reference-values-elements-dietary-reference-intakes-tables-2005.html ↵
- Dietary Supplement Fact Sheet: Magnesium. National Institutes of Health, Office of Dietary Supplements. http://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/. Updated July 13, 2009. Accessed November 12, 2017. ↵
- Tucker KL, Hannan MT, et al. Potassium, Magnesium, and Fruit and Vegetable Intakes Are Associated with Greater Bone Mineral Density in Elderly Men and Women. Am J ClinNutr. 1999; 69(4), 727–36. http://www.ajcn.org/cgi/pmidlookup?view=long&pmid=10197575. Accessed October 6, 2017. ↵
