My parents asked for information on their latest medicine, alendronate, which is sold as Fosamax by Merck. Hopefully, to try to improve their bone density. While the information on the drug is very informative, a better introduction to bones and bone function is needed to explain the role of this medicine.
Adult humans mostly have 206 bones, newly born babies have 350 but some of these fuse during development and growth. Bones have both a supportive and protective role and act as a mineral reservoir particularly for calcium and phosphorus. On a dry weight basis, bones are approximately 70% inorganic matter and 30% tissue. The composition of fresh bones is 25% water, 20% protein, 5% fat and ~50% mineral. As well as calcium and phosphorus, bones also contain magnesium, fluorine, chlorine and iron.
There is about 600-900 g phosphorus in the skeleton and it is important for many of the body’s chemical processes. It is an essential part of ATP which is “the universal energy currency of all known living organisms” (ref). There is a little more calcium (~1100g) and it is important for chemical processes and for maintaining body fluid balance.
The ability of bones to withstand excessive compression and the reason for their strength is from the fact that bones are made up of two layers. The denser compact outer layer surrounds an inner network of porous material. Bones respond to load and usage. There is bone loss if the bones are not used regularly, especially if some one is abnormally idle due to ill health. This is both bone loss as well as decalcification. This can be a problem if some one goes from bed rest to excessive exercise and is also a problem for astronauts when they live for a long time in a low gravity environment.
Bone loss is a serious issue as the body ages. There is a loss of both bone mass and a decrease in bone density. Once bone mass is reduced by 40%, osteoporosis is diagnosed. However, this diagnosis is not that easy to make. Interestingly, a diet low in calcium and protein does NOT accelerate, and large intakes of calcium after severe osteoporosis has been diagnosed may not slow down or reverse the osteoporosis process. The medicine that my parents have been diagnosed, however, inhibits bone resorption and will permit bone mineralization if sufficient calcium is available. Unfortunately, Fosamax is very unpleasant to consume as it cannot be taken with any food and with hardly any water*. Everything, it seems, reduces the gut absorption, which even under ideal conditions is less than 1%.
One very effective way to increase bone mass is to increase bone strength by doing physical exercise. For over ten years, Dr. Miriam E Nelson has been advocating strength training to strengthen bones and reduce osteoporosis. I bought my parents one of her earlier books: “Strong Women, Stay Young” after I heard her talk to the Nutrition department at Minnesota. I even bought myself weights, which admittedly I now do not use as yoga my exercise of choice. Perhaps I should buy Mum and Dad some weights to go with the book and then do some of the exercises with them when I am next home.
References (non internet linked):
Smith, A (1970) The Body, Penguin Books. Rather frighteningly, this book claims that all women have lost 50% of their bone mass by the age of seventy.
Davidson, S., Passmore, R., Brock, J.F. and Truswell, A.S. (1979) Human Nutrition and Dietetics, Churchill Livingstone, 7th edition. This was my text book as an undergraduate Nutrition major. It was my bible. Rather scarily, it claims that bone begin to atrophy by the age of 40. By the age of 40! Eck, where did I put those weights and where is that book…
Mum and Dad were anxious to let me know that they were told to take Fosamax with a glass (6 – 8 fl oz.) of water. This was confirmed by the books and websites I checked.