High fat diets can produce an increase in two types of bile acid stopping signals in our intestines to stem cells, which normally repair and regenerate the gut lining after digesting a meal; instead high fat diets cause cancer growth and this is especially true for patients with a mutation in the APC gene.
Scientists from the Salk Institute, California and Sydney Medical School, Australia have collaborated (1) to show that in people with colorectal cancer who commonly have a mutation in the APC gene, those people developed colorectal cancer much faster if they ate a high fat diet. In normal circumstances, the APC gene has a tumour-suppressing action because it controls how often cells divide, and so it is in people who have a mutation in this gene that scientists say will have a higher chance of developing colorectal cancer (writes Gilly Bertam).
Colorectal cancer can take decades to develop before tumours are found but the rates of it are increasing especially amongst younger people. Scientists believe one reason could be because younger generations are starting to eat high fat diets at an earlier age.
This led researchers to investigate why this was the case and what could be causing the increase.
We need bile acids to help us digest fats. There are around 30 different types of bile acids which are produced by our livers to help breakdown the fat particles in the fatty foods we eat so that we can digest them. Bile acids are important also because they send signals to stem cells in our intestinal lining to tell them to regenerate and repair after the damage caused by our digestive juices following a meal. The repair process is normally a slow and steady one and is controlled by a protein called FXR. Scientists saw that when bile acids increase, FXR loses its control over the speed at which cells regenerate and uncontrolled cell growth occurs. This is the start of cancer.
The scientists in the study identified that people with colorectal cancer commonly have a mutation in the APC gene and that those people with the mutation developed colorectal cancer much faster if they ate a high fat diet. In normal circumstances, the APC gene has a tumour suppressing action because it controls how often cells divide, and so it is in people who have a mutation in this gene that scientists say will have a higher chance of developing colorectal cancer.
The scientists used a mouse model and found that feeding them a high fat diet increased the amount of bile acids produced and saw a dramatic increase in cancer growth.
"It could be that when you’re genetically prone to get colon cancer, something like a high-fat diet is the second hit," said one of the lead researchers of the study, Ruth Yu.
The outcome of the study shows that people who have the APC gene mutation can be warned to change their diet early on and avoid this damage in their gut before any cancer can develop.
Chris Woollams, former Oxford University Biochemist and a founder of CANCERactive said, "Just as we believe that one size doesn't fit all for drugs so too with diet. We know there are 'health experts' who recommend the high fat Keto Diet for everybody with cancer, For the majority of people with colorectal cancer - and the APC mutation - the rigid 90%-of-your-calories-from-fat Keto Diet would be totally wrong, even dangerous. This is why we always recommend the flexibility of the Rainbow Diet. We have known one of the prime drivers of CRC is added sugar ever since the 2009 study from Johns Hopkins, and the Weill Cornell work. But we have also known for a long time that high saturated fat diets, involving foods like red meat, lard, coconut oil and cheese, cause secondary bile acids to form and these turn on the Cox-2 pathway in the gut, cause chronic inflammation and polyp formation and cancer."
Go to: Colorectal cancer overview - symptoms, causes and alternative treatments
Reference
- https://www.cell.com/cell/fulltext/S0092-8674(19)30099-6?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0 092867419300996%3Fshowall%3Dtrue