Matt Lewis
01-19-2003, 09:44 AM
Well after reading Delfí's introduction, i thought this would be an appropriate topic to touch on.
It has been my experience in listening to people with cystinuria that diets are of minimal success when it comes to reducing the occurance of cystine stones.
The main problem with trying to controll stone formation with diet is that cystine, the "problem molecule" in the disease, is not easily avoidable. In fact, in all practicality, i'd call it impossible. It is obtained from the amino acids in our food, whether we are vegans or meat eaters. We need protein, regardless of the source, and from protein comes the amino acids. Cystine is specifically obtained from the metabolism of the amino acid Methionine, or by intake of the amino acid cysteine, of which 2 molecules react to form one molecule of cystine (see the amino acids tutorial (http://www.cystinuria.org/rm101.htm) in "Room 101").
While the occurance of these amino acids are relativly rare in most protein, they do occur, and each serving of protein (be it from meat, nuts or tofu) will contain them. Since we need protein in our diets to be healthy, i see diet in terms of reducing the cystine intake as more trouble than it's worth.
However, theoretically the less you take in the less you should put out, so there still might be some merrit to avoiding foods high in Methionine and such.
Another form of diet which is much more effective is increasing the alkalinity of the urine. In short, cystine dissolves very poorly in pH (http://www.cystinuria.org/dictionary.htm) below 7. As the urine pH increases, the solubility of cystine increases dramatically. The pH of the urine (and rest of the body) can be controlled by diet. Veggies and some fruits are great for raising the urine pH. Veggies because of the alkalizing minerals they contain, and fruits because of the citrate they contain. (Citrate is converted to bicarbonate, which is the body's pH raising component) Foods like protein are bad for this, because they lower the body's pH. pH can also be raised by supplimenting the diet with baking soda (bicarbonate) or more medically with citrate carriers such as potassium citrate, sodium citrate, and calcium citrate.
While the elevation of pH is crucial to the solubility of cystine, the number one most important dietary modification to fight cystine stones is hands down water consumption. The principle being that if there is more liquid volume present as urine, more cystine will go into solution. This situation is very analagous to trying to dissolve a sugar cube in a drop of water or a bucket; obviously the one with more water (the bucket) will dissolve the sugar cube better than the single drop. (For more on this relationship see the stone prevention tutorial (http://www.cystinuria.org/rm101.htm))
These are just my thoughts. Much of this will be going into the 2nd part of the Stone Prevention tutorial which i'll be writing as soon as i can get things set up on my new computer. Let me know your thougts; what works for you and what doesn't.
Perhaps a poll is in order? ;)
Kind Regards,
matt
It has been my experience in listening to people with cystinuria that diets are of minimal success when it comes to reducing the occurance of cystine stones.
The main problem with trying to controll stone formation with diet is that cystine, the "problem molecule" in the disease, is not easily avoidable. In fact, in all practicality, i'd call it impossible. It is obtained from the amino acids in our food, whether we are vegans or meat eaters. We need protein, regardless of the source, and from protein comes the amino acids. Cystine is specifically obtained from the metabolism of the amino acid Methionine, or by intake of the amino acid cysteine, of which 2 molecules react to form one molecule of cystine (see the amino acids tutorial (http://www.cystinuria.org/rm101.htm) in "Room 101").
While the occurance of these amino acids are relativly rare in most protein, they do occur, and each serving of protein (be it from meat, nuts or tofu) will contain them. Since we need protein in our diets to be healthy, i see diet in terms of reducing the cystine intake as more trouble than it's worth.
However, theoretically the less you take in the less you should put out, so there still might be some merrit to avoiding foods high in Methionine and such.
Another form of diet which is much more effective is increasing the alkalinity of the urine. In short, cystine dissolves very poorly in pH (http://www.cystinuria.org/dictionary.htm) below 7. As the urine pH increases, the solubility of cystine increases dramatically. The pH of the urine (and rest of the body) can be controlled by diet. Veggies and some fruits are great for raising the urine pH. Veggies because of the alkalizing minerals they contain, and fruits because of the citrate they contain. (Citrate is converted to bicarbonate, which is the body's pH raising component) Foods like protein are bad for this, because they lower the body's pH. pH can also be raised by supplimenting the diet with baking soda (bicarbonate) or more medically with citrate carriers such as potassium citrate, sodium citrate, and calcium citrate.
While the elevation of pH is crucial to the solubility of cystine, the number one most important dietary modification to fight cystine stones is hands down water consumption. The principle being that if there is more liquid volume present as urine, more cystine will go into solution. This situation is very analagous to trying to dissolve a sugar cube in a drop of water or a bucket; obviously the one with more water (the bucket) will dissolve the sugar cube better than the single drop. (For more on this relationship see the stone prevention tutorial (http://www.cystinuria.org/rm101.htm))
These are just my thoughts. Much of this will be going into the 2nd part of the Stone Prevention tutorial which i'll be writing as soon as i can get things set up on my new computer. Let me know your thougts; what works for you and what doesn't.
Perhaps a poll is in order? ;)
Kind Regards,
matt