If teenagers could see the future and observe the state of their own bones half a century ahead, they might be inspired to prevent osteoporosis with lifestyle and dietary changes to avoid disability and premature death. Almost all cases of thinning bones could be avoided if youngsters exercised regularly, maintained normal vitamin D levels and ate plenty of calcium.

The stooped back and shorter spines so common in old age are almost always signs of osteoporosis, says Prof. Sebba.

Prof. Anthony Sebba, an osteoporosis expert at the University of South Florida constantly sees middleaged and elderly people who when young did not follow that advice.

"It's so frustrating. Osteoporosis is virtually preventible. If youngsters took this advice in time, they would be fine at the age of 80. Osteoporosis is almost a pediatric disease whose symptoms appear decades later," he says. "If every woman were assessed at 55, the risk would be brought down by 90 percent. It has no real symptoms; you don't feel it, so people are unaware that they have it unless they undergo a bone-density test. SEBBA, WHO was born in South Africa and comes from a long line of Lithuanian Jews, graduated for the University of Cape Town and completed his fellowship in rheumatology at Mount Sinai Medical Center in New York. He has been principal investigator in many osteoporosis studies and has lectured around the world on the the bone-thinning disease.

The experienced rheumatologist, who recently visited Israel for the second time since arriving with a buddy after the Yom Kippur War, is here to present data at a conference on how a unique once-a-week pill combining 5,600 International Units (IUs) of vitamin D with alendronate sodium (biphosphonate) can help fight bone thinning. The bone resorption inhibitor drug, just put on the market by Merck, is called Fosavance, and combines the vital vitamin with the company's Fosamax (sold in Israel as Fosalan).

Biphosphonates have been used for 100 years, originally to paint ship bottoms to repel barnacles; more recently, it has been utilized for coating the inside of metal pipes to prevent encrustation. But four decades ago, it was found to be good for promoting bone mass.

In the past 13 years, some 55 million prescriptions of Fosamax have been penned by US doctors, but "it is a shrinking market despite the ageing of the population. There are no public service ads about the danger of bone thinning. People just don't understand the implications of not treating osteoporosis. If a person suffers from high blood pressure and osteoporosis, has no health insurance and can afford to pay for only one prescription, I tell him or her to treat the bone thinning, because failure to treat can be even more deadly. After five years of taking the drug, one can probably stop for several years if you have not broken a bone before," Sebba suggests. Alendronate sodium works by inhibiting the activity of cells called osteoclasts that cause bone loss. Osteoclasts remove old bone cells that are then replaced by new bone cells. In osteoporosis, osteoclasts continue to function normally but the bone cells removed are not replaced in enough volume to sustain normal bone density. Taking the drug reduces the amount of old bone cells that are removed.

A year after a typical patient has a hip fracture and Sebba prescribes alendronate, only a quarter of them will still be taking it. Within a year of a hip fracture, as many as a third will die because of clots or other conditions. It's more effective to prevent fractures. Part of the compliance problem is that alendronate sodium must be taken on an empty stomach, swallowed only with tap water (not even mineral water or soda water), and the patient must be in an upright position for 30 minutes; if not, it could irritate the esophagus. It is a very safe drug, he stresses, but rare cases of damage to the jawbones and resulting dental problems have been connected to the taking of biphosphonate. ASKED IN a Jerusalem Post interview why the millions of Americans at risk from osteoporosis don't merely take cheap vitamin D drops (in water or juice) or tablets as well as alendronate sodium pills, Sebba explains: "Many people are too lazy or don't like to carry out their doctors' instructions. "There is very low compliance and too little awareness about the risks of vitamin D deficiency." Merck's combining the vitamin and biphosphonate was a major accomplishment, said Sebba, and taking the unified pill will make it easier for patients to follow doctors' advice.

Biphosphonates had to be taken daily, but then once-a-week pills were marketed, and they are the most frequently prescribed. There is also a once-a-year zolendronic acid, which is similar to alendronate sodium but has to be administered as an infusion in a clinic instead of being taken orally. "There has to be an encounter with a doctor for this and it is more expensive than weekly pills, so most people prefer a pill. In addition, people tend to be apprehensive about an intravenous drug that once taken cannot be removed from the system or stopped. But the infusion is just as effective," Sebba says. In the US, milk and orange juice are fortified with vitamin D, but in Israel, unpopular 1%-fat milk is ANTHONY SEBBA: Half of all 50 year olds in the Western world will suffer a bone fracture before they die. The disease is more common among women than men because of the halt of estrogen production at menopause. required by law to have it but 3%-fat milk does not. Milk to which vitamin D and calcium are added is sold for a top price, even though the added components are cheap. "In my country, many people don't consume dairy products, including milk, because they are or think they are lactose intolerant," says Sebba. Tobacco smoking, by the way, promotes osteoporosis. Coffee makes drinkers lose calcium that is somewhat replaced if they add milk.

It's better to get vitamin D naturally, as it's more easily produced in the skin or absorbed from food, but it's very hard to get in your diet, as it's found mostly in wild fish. So, says Sebba, people need a supplement. If they start with a deficiency of the vitamin, they will have to bring levels up to normal. It's easy to produce 5,000 units or so of vitamin D by exposing skin to the sun for just 20 minutes, declares the rheumatologist. "It doesn't matter what part of the body is exposed, or whether it's early in the morning with less intense sun. But one must be careful not to get sunburn."