No, Fosamax doesn't cause brittle bones. Not getting enough calcium and vitamin D does. You need at LEAST 1200 mg of calcium per day, and at least 400(not enough, imo.) to 800 I.U of Vit. D - preferably 800 or more- per day to build bone density. You can't take calcium by itself or vit. D by itself and expect to improve bone density either. Vit. D helps the calcium absorb into the bones. If you don't get enough of vit. D, the body just eats at the calcium and the bones won't absorb it. That means you will not maintain your bone density and be more susceptable to fractures. It drives me crazy when people complain about their bone density not improving when on Fosamax, and then I find out that they don't even get the required amounts of both calcium/vit. D. and/or not taking the Fosamax correctly. How can a person expect it to work when you don't bother to take as much of these things you can get?

Here is what to do:

Take TWO tablets of Caltrate 600mg Calcuim +D per day, one in morning, one at night(that's what the bottle says.). Also take Women's One a Day in the middle of the day. That one has 450mg of calcium + 800IU of Vit. D. This way, you have plenty of both coming in on top of the calcium and vit. D rich foods you should be eating. Read food labels when buying!

Also: Are you taking the Fopsamax correctly? NEVER take it with tap water. Tap water has all sorts of minerals and chemicals in it. Minerals, especially calcium, hinder the Fosamax's absorbtion into the body. The calcium bonds to the stuff, making the absorbtion of the medicine impossible. The other junk won't help absorbtion either.

Take the pill with spring water, NO minerals. I use Ice Mountain spring water. DO NOT use purified water to take it with, since they add back into the water, minerals to it. And, many companies actually use tap water instead, and just call it "purified" when it really isn't. Read the back of whatever spring water you choose to drink BEFORE taking Fosamax with it, to make sure it is NOT mineral type spring water. Fiji spring water is mineral water, for example.

I was told my the pharmacist to wait at LEAST two hours before eating food OR taking any medications to achieve the best and ther most absorbtion of the Fosamax. This REALLY has worked well for me, since my T scores in all areas have gone up significantly in the last 6 years. I found out I had osteoporosis a year after I went through menopause. My T scores where in the -3 range then, and none now are even near that. That's because I am downright anal in what I do to raise my bone density. I constantly read food labels when shopping, research what foods have the most calcium and vit. D, so when I do shop, I know what to buy, take the right suppliments, and excercise-must be two types: weight bearing(for the bones. This is stuff like walking or jogging or dancing-anything that bears your weight.) excercise AND strength training-for the muscles which also helps the bones build bone density, or it's worthless for the bones, and I do whatever else it takes to build and maintain my bone density.

YOU have to be anal about it also, or it will stay low like it is until you decide to do something about it.

I am a martial artist too. But, you can't be stupid and expect to keep going at whatever it is you do without being careful now, even if your bone density rose. You have to be smart and understand that well, you have osteoporosis and you are stuck with it, so you just have to re-arrange how you approach things. It's either that or break something.

Well, I know this is an old post I am replying to. But, this info will be useful to all who visit.

Hope this helps! :)