Field Notes

Study Shows How High-Fat Diets Increase Colon Cancer Risk

Epidemiologists have long warned that, in addition to causing obesity, eating too much fat and sugar puts a person at greater risk of colon cancer. Now, researchers at Temple University in Philadelphia have established a link that may explain why. The findings were published in the March issue of Cancer Prevention Research.

“There have always been questions about why things like diet and obesity are independent risk factors for colon cancer,” says Carmen Sapienza, PhD, a professor of pathology in Temple’s Fels Institute for Cancer Research and Molecular Biology and the study’s lead author. “This study suggests how and why high fat diets are linked to colon cancer.”

The researchers compared colon tissue in non-colon cancer patients with normal colon tissue in patients with the disease. In the normal tissue from patients with colon cancer, they found that epigenetic marks on genes involved in breaking down carbohydrates, lipids, and amino acids—abundant in the fatty Western diet—appeared to have been retrained. Epigenetic marks are chemical modifications that serve as on/off switches for many genes.

“These foods are changing the methylation patterns on a person’s insulin genes so that they express differently, pumping out more insulin than the body requires,” Sapienza says. “In people that have colon cancer, their glucose metabolic pathways and insulin signaling pathways are running at completely different levels than people who don’t have colon cancer.”

Sapienza says cancer cells love insulin, and studies have shown that tumors feed off of insulin. “Insulin is only supposed to be expressed in your pancreas, so having this extra insulin is bad,” he says.

Sapienza points out that people don’t usually get colon cancer until the age of 50 or older, so it’s unclear when the epigenetic modification of the genes begins. “The hypothesis is that the changes in the metabolic pathways happen first, and once they occur, if any kind of mutation happens that causes a cancerous polyp, you’re going to feed it through this excess insulin,” he says.

Sapienza says this study provides the first evidence of widespread epigenetic modification of metabolic pathway genes occurring in healthy colon tissue.

The researchers theorize that if modification in healthy tissue also could be found in other healthy tissues in the body, they may be used to diagnose or determine the likelihood of colon cancer through a saliva or blood test in addition to a colonoscopy.

— Source: Temple University


More Trans Fat Consumption Linked to Greater Aggression

Might the “Twinkie defense” have a scientific foundation after all? Researchers at the University of California, San Diego School of Medicine, have shown—by each of a range of measures, in men and women of all ages, in whites and minorities—that consumption of dietary trans fatty acids is associated with irritability and aggression.

The study of nearly 1,000 men and women provides the first evidence linking dietary trans fatty acids with adverse behaviors that impacted others, ranging from impatience to overt aggression. PLoS ONE has published the research, led by Beatrice Golomb, MD, PhD, an associate professor at the University of California, San Diego department of medicine, online.

The researchers used baseline dietary information and behavioral assessments of 945 adults to analyze the relationship between dietary trans fatty acids and aggression or irritability. The survey measured factors such as a life history of aggression, conflict tactics, and self-rated impatience and irritability as well as an “overt aggression” scale that tallied recent aggressive behaviors. Analyses were adjusted for sex, age, education, and use of alcohol or tobacco products.

“We found that greater trans fatty acids were significantly associated with greater aggression and were more consistently predictive of aggression and irritability across the measures tested than the other known aggression predictors that were assessed,” Golomb says. “If the association between trans fats and aggressive behavior proves to be causal, this adds further rationale to recommendations to avoid eating trans fats or including them in foods provided at institutions like schools and prisons since the detrimental effects of trans fats may extend beyond the person who consumes them to affect others.”

— Source: University of California, San Diego Health Sciences