SAN DIEGO – Obesity is a risk factor for colonic diverticulosis among women but not men, while a low-fiber diet was not found to be a risk factor in a recent study reported at the annual Digestive Disease Week.
“The classic teaching in medical school is that a low-fiber diet increases constipation, which in turn increases the risk of diverticula,” explained lead author Dr. Anne Peery, assistant professor of medicine at the University of North Carolina, Chapel Hill. “This is in textbooks and on your boards. But there is no association between low-fiber dietary intake and diverticula.
“There is, however, evidence from other studies that a high-fiber diet and increased physical activity decrease the risk of developing complications from diverticula,” Dr. Peery added. She noted that the study was designed to look at risk factors for developing diverticula, not at complications.
Dr. Anne Peery
“The provocative findings from our study are twofold: We found that the prevalence of diverticula is higher in men and lower in women younger than age 50, and that obesity is a risk factor for diverticula in women but not in men,” Dr Peery said.
“The age-related gender differences we identified were quite surprising, and suggest that something is going on in women under the age of 50 that may be estrogen-related. This opens up an avenue of research,” she noted.
Colonic diverticula are common, and they are important because of complications such as hemorrhage, perforation, and inflammation. They also pose a substantial health burden, accounting for 2.5 million office visits and 4,500 deaths each year in the United States.
“Despite this, we know very little about risk factors for colonic diverticula,” Dr. Peery noted.
The prospective study recruited 624 patients between the ages of 30 years and 80 years undergoing a first screening colonoscopy between 2013 and 2015 at the University of North Carolina in Chapel Hill. Prior to undergoing the procedure, each participant was interviewed using validated instruments to assess diet and physical activity. Each participant had a detailed examination for colonic diverticula, with a research assistant present during the entire colonoscopy.
“The presence or absence of diverticula reported in previous studies were extracted from colonoscopy reports. Our study assessed risk factors prior to undergoing colonoscopy,” she emphasized. “This is one of the study strengths.”
Not surprisingly, the study showed that the prevalence of diverticula (or “tics”) increased with age. Younger than age 50, the prevalence was higher in men than in women, after which prevalence equalized with age.
In the study population, 124 men had diverticula and 150 did not; 136 women had diverticula and 214 did not. Women with diverticula were more likely to be older, white, and have a higher body mass index (BMI).
The investigators looked at several measures of obesity, including BMI, waist circumference, and waist-to-height ratio. Women with greater BMI were at increased risk for diverticula, a risk relationship that was not seen in men. The risk of developing six or more diverticula was more than twofold greater in obese women.
Men with a greater waist circumference (more than 102 cm) had no increased risk for diverticula, while women with a greater waist circumference (more than 88 cm) were at increased risk of any diverticula, as well as having six or more diverticula.
A similar pattern was observed for waist-to-height ratio, which some experts believe is related to obesity, according to Dr. Peery. No association was found in men. But for women, a high-risk waist-to-height ratio increased the risk of diverticula, and the risk of having six or more diverticula was almost twice as great in these women, compared with men.
The investigators then measured the association between dietary fiber and physical activity with diverticula. No associations with diverticula were found in any quartile (lowest to highest) for both physical activity and dietary fiber intake.
In an interview, Dr. Peery speculated on why women have a lower prevalence of “tics,” compared with men younger than age 50. She said there are gender-related differences in the way fat is stored and metabolized.
“Obese women have more visceral adiposity that men, and they tend to eat more carbohydrates, while obese men have higher alcohol and meat intake. These differences will be studied in greater depth as they relate to diverticula and complications,” she noted.