Obesity is known to increase the risk for at least 13 cancers, but a new study suggests the type of fat in the diet, not just body fat itself, may play an important role in how tumors grow.
In research published in Nature Metabolism, scientists at the Ludwig Institute for Cancer Research found that obese mice fed high-fat diets derived from butter, lard or beef tallow developed faster-growing tumors and weaker anti-tumor immune responses than equally obese mice fed diets based on olive oil, coconut oil or palm oil.
“Our study reveals that the source of dietary fat, not adiposity itself, is the primary factor that influences tumor growth in obese mice,” said lead author Lydia Lynch, a professor at Princeton University and member of the Ludwig Institute.
The team found that animal-fat diets led to higher levels of metabolic byproducts called acylcarnitines, which suppressed the activity of key immune cells, including cytotoxic T cells and natural killer (NK) cells. These immune cells normally help identify and destroy cancer cells. In contrast, plant-fat diets did not produce the same suppression, and in the case of palm oil, even improved anti-tumor immune activity.
“These findings highlight the significance of diet in maintaining a healthy immune system,” Lynch said. “More important, they indicate that modifications to fat in the diet may improve outcomes in obese people undergoing treatment for cancer and suggest such measures should be clinically evaluated as a potential dietary intervention for such patients.”
While the study was conducted in mice, the researchers say the findings may help guide future clinical research on dietary fat sources as part of cancer prevention or treatment strategies for people living with obesity.
This study was supported by the Ludwig Institute for Cancer Research, the Mark Foundation, the U.S. National Institutes of Health, Science Foundation Ireland, the European Research Council, the Cancer Research Institute and the Landry Cancer Biology Consortium.