Q. Is Forteo, the new medication for osteoporosis, safe and effective? Are there nutritional corrections that produce the same effect as Forteo?
A. Forteo is one of a new class of medications made possible by “recombinant DNA technology,” and many more will follow. Recombinant DNA technology uses microorganisms to produce human proteins, such as parathyroid hormone, by inserting a human gene for making parathyroid hormone into the DNA of the microorganism.
Forteo is a form of the parathyroid hormone, just like the one that we make, only made by a microorganism. Unlike other osteoporosis medications, such as Fosamax, which block the breakdown of bone, parathyroid hormone helps us form new bone.
There is no doubt that long-term elevation of parathyroid hormone leads to bone loss. However, it appears that when parathyroid hormone is given by injection once daily it can actually stimulate an increase in bone mass and bone strength, and nutritional changes don’t do the same thing. This paradox may be hard to explain, but clinical trials show that, compared to a placebo, daily Forteo injections increased bone mineral density by 5% or more in most postmenopausal women and reduced the risk of spinal fractures by 65%. These impressive results, unfortunately, come at a price of more than $500 per month.
The parathyroid hormone is only one of several hormones that maintain tight control over circulating calcium levels. Calcium must be rigidly controlled because, among other functions, it regulates our heart rhythm, and a change of just 10% from normal blood calcium level is life threatening. About 99% of the body’s calcium is contained in our bones, and we are constantly moving calcium back and forth from bone to blood. Tiny alterations of blood calcium levels upset this delicate balance of calcium movement and can lead to a wide range of problems. For instance, too much calcium in the blood can lead to kidney stones while too little can lead to heart failure. Parathyroid hormone is probably the most important regulator of calcium.
Diets that are low in calcium or vitamin D may cause the long-term elevation of parathyroid hormone mentioned above, which brings on bone loss. Supplements of calcium and vitamin D have long been used to reduce the risk of osteoporosis. It is less well-known that diets high in phosphorus, such as the high animal-protein diets now popular, increase the risk of osteoporosis through the same elevation of parathyroid hormone. Many Americans overuse soft drinks, which are high in phosphorus, and add to the already excessive phosphorus in the typical American diet. Such diets lead to high body acidity, which promotes calcium loss as well as having many other unfavorable results. Although they need not be, these diets also tend to be low in the foods rich in vitamin K, and insufficient vitamin K is known to increase the risk of osteoporosis. Pantothenic acid supplements can reduce bone loss when it is due to elevated phosphorus intake, but it is prudent to simply keep phosphorus intake in proper balance with calcium intake.
Recombinant DNA technology, with the ability to create new medications such as synthetic parathyroid hormone, has a bright future. No less promising is the prospect of a long and healthy life through thoughtful lifestyle adaptations.
This article appears in September 24 • 2004.