The human body uses bones for support, protection and movement. The strength and health of the skeletal structure is dependent on several factors, including nutrition. Because bones are living tissue, they rebuild throughout life, but they don't always remain strong. In conditions such as osteoporosis, for example, the bones weaken and become susceptible to fracture from only minor trauma. To help prevent brittle bones, it's important to understand what make bones weak and why certain nutrients, such as calcium and magnesium, are vital in the diet.
Bone Physiology
The two major types of cells responsible for depositing and absorbing bone are called osteoblasts and osteoclasts. As noted in the "Textbook of Medical Physiology," bone is continually being remodeled by osteoblasts, which create bone, and absorbed by osteoclasts, which destroy bone. This process takes place because bone responds to the stress placed upon it. Bone becomes thicker where it needs more strength; if a person is sedentary and does not challenge the bones, the bones will weaken.
Minerals
The human body uses minerals to build bones, create hormones and perform other functions, such as muscle contractions. Macro minerals are those needed in larger amounts and include calcium, phosphorus, magnesium, sodium, potassium, chloride and sulfur. Trace minerals are required in small amounts and include iron, manganese, copper, iodine, zinc, cobalt, fluoride and selenium. Both macro minerals and trace minerals are introduced into the body through diet, primarily fruits and vegetables. Calcium is also found in dairy products.
Calcium
The body stores more than 99 percent of its calcium in the bones and teeth, while the rest is in the blood, the muscles and the fluid between cells. Calcium is required for strong bones and can be affected by weight-bearing exercise, hormone levels and dietary factors. If the body removes more calcium than it replaces, the bones will become weaker and will be more likely to fracture. The National Institutes of Health notes that bones grow fastest during adolescence, making it especially important that people consume enough calcium and participate in weight-bearing physical activity during those years.
Magnesium
Magnesium is essential to good health. Approximately 50 percent of the body's magnesium is found in bone. The other half is predominantly inside cells of body tissues and organs. Magnesium is involved in hundreds of biochemical reactions in the body, including those related to muscle and nerve function, heart function and immune system function. Magnesium forms a major portion of the bone salts that give bone its strength.
Expert Insight
Nutrient needs should be met primarily through foods rather than supplements. Calcium is found in dairy products and is often consumed in milk. Nondairy sources include collards, bok choy, fortified soy milk and baked beans. Magnesium is found in whole grains, legumes and dark green leafy vegetables. Eating a variety of vegetables helps ensure that the body is getting the proper amount of magnesium.
References
- MedlinePlus: Bone Diseases
- National Institutes of Health: Bone Health
- "Textbook of Medical Physiology"; A.C. Guyton and J.E. Hall; 2000
- MedlinePlus: Minerals
- MedlinePlus: Calcium
- National Institutes of Health's Office of Dietary Supplements: Magnesium
