Dietary calcium has been shown reduce the risk of osteoporosis and brittle bones. Calcium is also an electrolyte, which plays an important role in muscle function, including the regulation of heart muscle rhythm (or heart rate), and fluid balance. Bone is living tissue, continuously replacing new cells. Our skeletal structure is our calcium "bank," or storage system. When blood calcium drops below normal range, regulating hormones trigger the "withdrawal" of calcium from the bones to maintain normal blood levels to supply the demands of the tissues. Increased dietary calcium raises blood calcium levels, triggering the hormonal response to build bone cells. As we age, the hormone that cues the process of bone building dwindles, which is why maintaining bone health becomes more difficult. Building a good store of calcium in our younger years leads to stronger bones in our senior years.
But, it's not the only nutrient that matters. Studies show that most Americans, including infants, are not getting enough Vitamin D. It has recently been discovered that the recommended 400 IU per day is not enough. Most researchers now recommend a minimum of 1000IU per day for adults, especially in the northern regions where exposure to sunlight is reduced. Vitamin D is necessary for the transport of calcium and other minerals from the digestive tract into the blood. Vitamin D deficiencies have also been linked to migraines, breast cancer, autism, and all inflammatory illnesses such as heart disease, arthritis, and asthma. The recommended amounts of vitamin D are difficult to obtain from the diet alone, as the limited variety of foods rich in vit. D such as anchovies, herring, tuna in oil, and salmon, are not typically found on our daily dinner table. Thought milk and dairy products are fortified, and vit. D is manufactured in our bodies through sunlight, we are still falling short. Most fish oil capsules do not contain vit. D! Calcium supplements that include vit. D typicaly offer 600 IU per dose.
Other nutrients that keep the bones going strong are the alkaline residues generated from fruits and vegetables. They neutralize acid residues produced by grains and proteins in the diet. Without the alkali supply in the diet, the bones are again called upon to produce alkali. If those fruits and vegetables include leafy greens like spinach, kale, collards, or salad greens, their vitamin K may also strengthen bones. "Vitamin K is required to build bone matrix" according to Bess-Dawson Hughes, director of the Bone Metabolism Laboratory at Tuft's Human Nutrition Research Center on Aging. (One serving of greens a day supplies 150-250mcg of Vit. K; more than enough!)
Exercise also matters to the bones. Stress to the bones in the form of weight-bearing stimulates the uptake of calcium. Just about any weight-bearing exercise will do, including walking. Almost any activity other than swimming or bicycling is considered weight-bearing!