How does high fat in the diet lead to colon cancer?
Eating a high fat diet is linked to increased risk of developing colon cancer. Researchers from Temple University say they have discovered how sugar and fat in the diet alter metabolic pathway genes to lead to cancer.
According to the study, published in the journal Cancer Prevention Research, carbohydrates, fat and amino acids that are commonly consumed in the Western diet changes an important process involved in encoding genes, called DNA methylation.
For the study, the researchers compared DNA methylation in normal colon mucosa between patients with colon cancer and patients without cancer. They found differences in the way fats are metabolized that changes gene expression in the patients with cancer.
When DNA is replicated, methylation occurs, which is an epigenetic process that changes the way genes are expressed. Epigenetic changes are normal, but they can also lead to disease.
Specifically, the researchers found high fat; sugar and high carbohydrate foods change the methylation pattern of insulin genes that causes abnormal cell growth that can turn to pre-cancerous polyps and colon cancer.
It turns out that cancer cells ‘feed’ on insulin. Fatty and high calorie foods promote unnecessary insulin production.
Carmen Sapienza, professor of pathology in Temple's Fels Institute for Cancer Research and Molecular Biology, the study's lead author said in a press release, "This study suggests how and why high fat diets are linked to colon cancer." Researchers haven’t understood how fat in the diet leads to cancer. He explains, "Insulin is only supposed to be expressed in your pancreas, so having this extra insulin is bad.”
People are more prone to develop colon cancer after age 50, making it unclear when methylation changes start. Sapienza says the theory is that metabolic pathways change first and then if any sort of cell mutation occurs it can lead to cancer. Past studies have also shown a high fat diet fuels the spread of cancer, correlating with the current finding.
The finding of how fatty foods can cause colon cancer could lead to better ways to detect the disease through saliva tests in addition to colonoscopy, which is the ‘gold standard’ for colorectal cancer screening.
Cancer Prevention Research
“Epigenetic Differences in Normal Colon Mucosa of Cancer Patients Suggest Altered Dietary Metabolic Pathways.”
Matthew L. Silviera, Brian P. Smith, Jasmine Powell, and Carmen Sapienza
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