Posted 3/9/2013 7:09 PM (GMT 0)
This is something I read from a study and got me a little worried about taking arginine.
Arginine and cancer growth
It has been known since the 1950s that arginine can stop the growth of some types of cancer cells. The idea of creating an "imbalance" of amino acids to cripple the growth of cancer cells was published in 1958. Cancer cells, just like normal cells, rely on certain amino acids for growth. The idea of overloading cancer cells with amino acids they don't want, and starving them of ones they do, has since proven to be a viable approach to cancer treatment.
Some cancers are hindered by excess arginine. Researchers in Japan gave rats infusions of arginine at the same time they were implanted with Yoshida sarcoma, and arginine proved very beneficial at slowing this cancer down at the early stages. It also inhibited metastases. Fifty percent of the animals receiving arginine had metastases to the liver versus 100% for those not receiving it. Similarly, 75% had lung metastases versus 100%. In the arginine-infused animals, the metastases were smaller and more localized. In addition, arginine helped maintain nitrogen balance and increased the activity of immune cells. Cancer causes alterations in the natural balance of amino acids: arginine was able to prevent this.
In other studies, the growth of human breast cancer cells (MCF-7) in vitro has been slowed with supplemental arginine. Arginine can also block the growth of mammary tumors in rodents.
Arginine has opposite effects on some cancers
Arginine does not always stop the growth of cancer. It can do the opposite. Arginine-induced growth has actually been used to good effect in an experiment where researchers were trying to put more cancer cells in the S-phase where they would be more readily killed by a certain chemotherapeutic drug. (Under normal circumstances, however, enhancing growth is obviously not desirable.)
Research shows that at least one pancreatic cancer cell line is arginine-dependent. And other studies show that if arginine is given at a certain phase of cancer development, it can promote, rather than block, growth.
Human Cancer Cell
The reason that arginine can act differently, depending on the cancer, probably has to do with an enzyme known as arginase. If the cancer creates a lot of the enzyme, it appears that it will use arginine to promote growth by converting it to L-ornithine. If the cancer doesn't create much arginase, it probably converts arginine to nitric oxide instead. Nitric oxide is used by immune cells to fight cancer. Since cancer cells are not tested for arginase, it's impossible to tell what effect arginine will have on cell growth. For that reason, arginine's role at this time is limited to its potential use as an immune stimulant during traditional cancer treatment, along with fish oil.