There’s More to the Vitamin D Story
by Sheldon S. Zinberg, M.D.
Milk, butter, eggs, fortified cereals, and seafood are all good food sources of vitamin D. As I’ve previously said, exposure to the sun is important because sunlight actually helps our body produce vitamin D. But we’re also told that exposure to the sun is largely responsible for skin aging, skin cancer, and the development of melanoma. Because of this, the authorities who urge us to limit our exposure to the sun are quite correct. But if a lack of sunlight is coupled with a poor dietary intake, vitamin D deficiency can develop. This sequence of events is common in lots of us older folks, but particularly in people who are institutionalized and also in the homebound elderly.
The importance of vitamin D is that it increases the utilization and absorption of calcium. In the past, we believed that 400 IU of vitamin D was the appropriate daily requirement. Now, however, studies have shown that some people have low blood levels of vitamin D despite that intake – and that bone fractures are more common in those people. Because of these findings, most doctors have come to recommend that the daily intake of vitamin D be increased to at least 800 International Units. Most multivitamin pills have about 400 IU in each pill and many supplemental calcium pills have vitamin D added to them. Women and older men need about 1,200 mg of calcium a day and most diets only have about 700 mg to 800 mg a day—so supplements of vitamin D and calcium are important. We’ll talk more about this later.
Treatment and Prevention
Although estrogen and testosterone deficiency accelerates bone loss, hormone replacement therapy is reserved for exceptional cases. Because of their potential to produce harmful side effects, they are no longer part of the routine regimen against osteoporosis. Calcium and vitamin D supplementation, however, are extremely valuable and should be used in the amounts previously discussed unless your physician suggests otherwise.
As discussed in my prior “Boomer Chat”, treatment and prevention of osteoporosis is directed at stimulating or assisting the friendly osteoblasts (the bone makers) to get on with their work of producing bone—and discouraging those nasty little osteoclasts (the bone takers) from taking bone away from us. To do this, we have to give the osteoblasts the appropriate tools, the most important of which (in addition to calcium and vitamin D) are exercise, bone sparing medications, and some other precautionary measures.
While accelerated bone loss is associated with diets deficient in calcium or vitamin D and disorders that impair the absorption, knowledge of other demineralizing influences can enable us to employ some of these precautionary measures. For example:
The excessive ingestion of vitamin A and cigarette smoking can increase the risk of bone loss and osteoporosis. Recent research also suggests that women who drink more than three cups of coffee a day may further decrease their bone density. People who are immobilized due to illness and those who have a sedentary lifestyle (as in the case of couch potatoes) are also subject to a more pronounced loss of bone.
Resistance Training and Osteoporosis
Resistance training and other forms of exercise that enhance osteoblastic activity can be extremely important in fighting osteoporosis. In one study, the bone density of the femoral neck,where so many fractures occur, was increased by 3.8 percentafter just 16 weeks of resistance training. In another study thatinvolved post-menopausal women from 50 to 70 years old, thebone mineral density of the lumbar spine was increased by 6.3percent after one year of training. During this same period oftime, the control group that was not involved in the trainingprogram experienced a 3.7 percent loss of bone mineral density. This amounted to an actual difference of 10 percent betweenthose who were in training and those who did not train. Because strong muscles are associated withstrong bones, strengthening our muscles will, in turn, strengthenour bones. Walking, jogging, strength training, vibration training, and a host ofother exercises can strengthen yourmuscles and your bones.
So what’s the take away? The important thing to remember is that Prevention is even better than Cure. Retarding the progress—or even preventing—osteoporosis with some of these measures is fareasier and more effective than treating advanced osteoporosisafter it has become established.