Author: Bonnie Brock, NMD, RD, MPH
Full disclosure: I love talking about, teaching about, cooking for and assessing the health of bones. Maybe it’s weird, but I find bones to be one of the most genius evolutionary developments in our bodies. Bones are rigid organs that make-up the skeleton of vertebrates. As a living matrix of collagen and calcium phosphate, bones support and protect the various organs of the body, produce red and white blood cells, and store minerals. It’s the mineral storage role that makes bones so evolutionarily amazing. You see, precise calcium levels are so important to the human body that bones represent a calcium repository or “in-body bank account” if you will. Calcium plays an important role in one of the body’s most vital functions; muscle contraction. And, one of your most important organs is essentially muscle, makes calcium critical for life. If calcium levels fall below a crucial range, the muscles can’t relax after contracting, and become stiff and stuck. So, humans have evolved to store calcium in the body as bones so we never run out. Kinda cool, huh?
Calcium balance in the body is controlled by a small but important gland, the parathyroid gland in the neck. It controls calcium homeostasis by producing a hormone that stimulates the release of calcium by bones into the bloodstream, regulates the absorption of calcium from food by the intestines, directs the conservation of calcium by the kidneys and stimulates cells in the kidney to transform weaker forms of vitamin D into the form that is strongest at absorbing calcium from the intestines. All these actions help keep calcium levels stable in the body.
It is extremely important to eat a diet sufficient in calcium. Food sources include dairy products, primarily cheese, fortified foods like cereals, soy milk, and orange juice, and some vegetables, mainly broccoli, kale, mustard greens, Bok choy and Brussel sprouts. And one of the best sources of calcium is one you may never guess; blackstrap molasses. While there are many common foods that contain calcium, the body doesn’t completely absorb all the calcium you eat. In fact, only about 30 percent of calcium is absorbed from dairy products and 50 percent of calcium from plant-based sources. So while you may think you are eating a lot of calcium, you are probably only absorbing a fraction, so keep your intake high! The greatest positive influence on calcium absorption comes from having adequate serum levels of vitamin D. People deficient in vitamin D absorb less than 15 percent of calcium from the foods they eat. In fact, activated Vit D is called “calcitriol” and works with parathyroid to keep calcium levels constant.
And while calcium and vitamin D are critically important for bone health, many other vitamins and minerals play a role in maintaining healthy bones. Phosphorus is a mineral that works in conjunction with calcium to build strong bones. Balance between the two is key and too much phosphorus can decrease the amount of calcium in your body, leading to bone loss. Think of a tug of war between calcium and phosphorus and you don’t want either side to “overtake” the other. Dark colas are loaded with phosphoric acid and may contribute to too much phosphorus in the blood and in turn, weaken bones, so it is important to limit dark colas to a reasonable amount. Magnesium is another mineral critical to bone health by playing a role in the activity of the parathyroid gland. In fact, magnesium is needed for more than 300 biochemical reactions in the body and helps to maintain normal nerve and muscle function, supports a healthy immune system, keeps the heartbeat steady, and helps adjust blood glucose levels. Food sources of magnesium include greens, nuts, seeds, dry beans, whole grains, wheat germ, wheat and oat bran. There are several different forms of magnesium supplements, each working slightly differently in the body and you should work with your healthcare practitioner to select a form that is right for you.
And a discussion of bone health would not be complete without touching on the subject of exercise. Bones adapt to the force loads placed on them, becoming thicker and stronger under stress and use and weaker and thinner when unused. The loading forces generated by muscle contraction during exercise can actually make your bones stronger! Simple aerobic exercises like walking, jogging, and running could provide an important role in maintaining and/or increasing bone density in women. Walking is an inexpensive, practical exercise associated with low injury rates and high acceptability among the elderly. For these reasons, walking could be an appropriate approach to prevent osteoporosis and maintain bone mass. Strength-training throughout life is also an important bone protection activity.
