Studies find significant variations in human gut anatomy

New research finds there is significant variation in the anatomy of the human digestive system, with possibly marked differences between healthy individuals. These findings have implications for understanding the role that the anatomy of the digestive tract can play in influencing human health, as well as providing potential insights into medical diagnoses and the gut microbial ecosystem.

“There was research over a century ago that found variability in the relative length of the human intestine, but this area has been largely neglected since then,” said Amanda Hale, one of the study’s authors and a Ph.D. candidate at North Carolina State University. “When we started exploring this issue, we were surprised by the level of variability we found.”

“If you talk to four different people, chances are they all have different guts, in terms of the relative sizes of the organs that make up those systems,” said Erin McKenney, corresponding study author and assistant. professor of applied ecology at NC State. “For example, the cecum is an organ found at the junction of the large and small intestines. One person may have a cecum that is only a few centimeters long, while another may have a coin purse-sized cecum. And we found similar variability for many digestive organs.”

In another striking example, researchers found that women tend to have longer small intestines than men.

“Because having a longer small intestine helps you extract nutrients from your diet, these findings support the canalization hypothesis, which states that women are better able to survive periods of stress,” Hale said.

“Given that there is much more variation in human gut anatomy than we thought, this can inform our understanding of what drives various health-related problems and how we treat them,” said McKenney. “Basically, now that we know this variability exists, it raises a number of research questions that need to be explored.”

For the study, the researchers measured the digestive organs of 45 people who donated their remains to the Anatomical Gifts Program at Duke University School of Medicine.

As well as highlighting the unpredictable variability in human anatomy, this project also led to a rediscovery of the importance of teaching anatomical variations to medical students.

“This is especially important in medical training, because if students are only learning about ‘normal’ or ‘average’ anatomy, it means they won’t be familiar with the scope of human variation,” said Roxanne Larsen, co-author of the paper and professor of medical sciences. veterinary and biomedicine at the University of Minnesota. “It is becoming increasingly clear that the medical field is moving towards individualized treatment to improve patient outcomes and overall health and well-being. Gathering experience in understanding anatomical variations can play an important role in helping future clinicians understand the importance of individualized treatment.”

“We are excited about this discovery and the future directions for this work,” said McKenney. “This underscores how little we know about our own bodies.”

The paper, “Hidden Diversity: Comparative Functional Morphology of Humans and Other Species,” will be published April 24 in the open access journal FriendJ. This paper was co-authored by Janiaya Anderson, a former NC State scholar; Colleen Grant, former research scientist at NC State; and by Rob Dunn, William Neal Reynolds Professor of Applied Ecology and Senior Vice Chancellor for University Interdisciplinary Programs at NC State.