October 3, 2013
Pig Study Suggests Humans Are Predisposed To Overeating
Brett Smith for redOrbit.com - Your Universe Online
By studying the eating habits of almost 1,200 pigs, Danish researchers have found evidence that humans may be genetically predisposed to overeating.
Study author Haja Kadarmideen, a health and medical science professor at the University of Copenhagen, said his team wanted to learn why some of us seem more predisposed to reaching for the cookie jar. They chose to study pigs because they are a well-known model for studying human obesity due to similar genomes and digestive systems between the two species.
“Why do some humans have a compulsive or comforting behavior to overeat, while others have control over their eating habits?” he asked. “Is it behavioral, for example when we are stressed or happy or sad, or are we genetically programmed to seek more food than we need?”
With the assistance of the Pig Research Centre from the Danish Agriculture and Food Council, scientists monitored their pigs’ eating habits while tracking their weight gain. The researchers also used genomic chip technology to create a genetic profile at 60,000 locations within the entire genome of each pig.
“We linked this whole genomic profile and eating behavior observations on all pigs via genome wide association studies to detect eating behavior genes – a big task equivalent to finding polar bears in a snowstorm,” Kadarmideen said.
According to their report, published in the journal PLoS ONE, the Danish team found large differences in the pigs’ eating habits, with animals with certain genetic variants regularly overeating. The researchers said there was clear evidence these pigs were genetically programmed to eat more than others.
“This is the first study in the world looking at pig to human comparative genetic mapping to reveal key genes on the human genome (e.g. on chromosomes 6 and 17) that are known to be involved in human obesity and some new genes; together they may explain why we crave for (more and sometimes unhealthy) food and why some of us overeat, so consequently developing obesity and diabetes, both of which are key societal and public health problems,” Kadarmideen said.
The researchers said a simple blood test could eventually be used to determine if someone is susceptible to unhealthy eating habits.
“Our pig model research indicates that eating behaviors runs in families,” Kadarmideen said. “If a mother or father or both had unhealthy eating habits they are likely to pass on some part of their habits to their children through their DNA.”
“However, not all children in the same family are similar in eating behavior and this is because they may have received different variants of eating behavior genes, which could lead to obesity,” he added. “There is also an environmental and psychological influence to consider, the ‘epigenetic’ factor and ‘fetal programming’ in the mother’s womb that can permanently affect the eating behavior of children. Overall it is a complex issue that needs further investigation.”
The Danish scientist said he could envision a day when “unhealthy eating behavior” is considered a disability issue.
“I believe more follow-up studies would strengthen our findings that some people cannot stop ‘pigging out’ as it is written in their DNA,” Kadarmideen said. “Once we are aware that this might be the issue, we can then be more understanding and helpful and encourage lifestyle and behavioral changes to offset the actions of these potential obesity genes.”