New York, Dec 13: Researchers have found that intermittent fasting inhibits the development and progression of the most common type of childhood leukemia. This strategy was not effective, however, in another type of blood cancer that commonly strikes adults.
 
"This study using mouse models indicates that the effects of fasting on blood cancers are type-dependent and provides a platform for identifying new targets for leukemia treatments," said senior author of the study Chengcheng (Alec) Zhang, Associate Professor at University of Texas Southwestern Medical Center in the US.
 
"We also identified a mechanism responsible for the differing response to the fasting treatment," he added. Acute lymphoblastic leukemia, the most common type of leukemia found in children, can occur at any age. Acute myeloid leukemia (AML) is more common in adults.
 
The two types of leukemia arise from different bone marrow-derived blood cells, he explained. Acute lymphoblastic leukemia affects B cells and T cells, two types of the immune system's disease-fighting white blood cells. AML targets other types of white blood cells such as macrophages and granulocytes, among other cells.In both ALL and AML, the cancerous cells remain immature yet proliferate uncontrollably.
 
Those cells fail to work well and displace healthy blood cells, leading to anemia and infection. They may also infiltrate into tissues and thus cause problems.The researchers created several mouse models of acute leukemia and tried various dietary restriction plans. 
 
They used green or yellow florescent proteins to mark the cancer cells so they could trace them and determine if their levels rose or fell in response to the fasting treatment, Zhang explained.
 
 "Strikingly, we found that in models of ALL, a regimen consisting of six cycles of one day of fasting followed by one day of feeding completely inhibited cancer development," he said. 
 
 At the end of seven weeks, the fasted mice had virtually no detectible cancerous cells compared to an average of nearly 68 per cent of cells found to be cancerous in the test areas of the non-fasted mice, showed the findings published online in the journal Nature Medicine.
 
 "Mice in the ALL model group that ate normally died within 59 days, while 75 percent of the fasted mice survived more than 120 days without signs of leukemia,"  Zhang said.
 
 Fasting is known to reduce the level of leptin, a cell signalling molecule created by fat tissue. 
 
 "We found that fasting decreased the levels of leptin circulating in the bloodstream as well as decreased the leptin levels in the bone marrow," he added.
 
 Interestingly, acute myeloid leukemia was associated with higher levels of leptin receptors that were unaffected by fasting, which could help explain why the fasting treatment was ineffective against that form of leukemia.