It was indicated that the inverse association between colon cancer and folate was stronger with supplemental folate than with dietary folate. A new study in rats, appearing in the October issue of the journal Nature Medicine, represents perhaps the first time a gene was successfully given via an oral route. Until now, genes have been administered experimentally via either nasal spray, in the case of a cystic fibrosis trial, or by injection, for other diseases. In this latest study, it was reported that rats were able to digest lactose and gained weight after being fed genes to correct the common inherited human condition, lactose intolerance. In contrast, seven other lactose intolerant rats that did not get the gene were unable to digest the lactose and all lost weight.
Lactose intolerance affects about half the Earth's population.
It affects most people in some Southeast Asia and African countries, but less than 5 percent of people in Northern Europe. To get the rats to incorporate the gene into their cells, the gene was first inserted into a viral vector that had most of its own genes removed. Then, the virus with the lactose gene was force-fed to the rats via a tube to ensure the rats consumed a known dose of the gene. The virus was able to specifically infect the cells of the rats' gastrointestinal system, particularly the epithelial cells of the stomach and small intestine. There were no signs of virus elsewhere in the rat.