Researchers at Harvard recently uncovered a clue as to why some people with diverticulosis go on the develop diverticulitis and some do not. Diverticulosis is having out-pockets of the lining of the colon (diverticula) extruding through weaknesses in the muscular layers of the colon wall. When the diverticula get inflamed, it is diverticulitis, which eventually occurs in 10 – 25% of people with diverticulosis. Diverticulitis results in more than 200,000 hospitalizations that cost more than 2 billion dollars per year and can result in emergency surgery.
About 50% of the people in the U.S. over the age of 60 have diverticulosis. The prevalence of diverticulosis increased from an estimated 10% in the 1920s to about 50% by the late 1960s, perhaps due to less roughage in the diet. However, a 2012, study by Perry AF et al in the journal Gastroenterology concluded, “A high-fiber diet and increased frequency of bowel movements are associated with greater, rather than lower, prevalence of diverticulosis.” The Perry et al study involved more than 2,000 participants, who underwent outpatient colonoscopies and were asked about diet.
Furthermore, diverticulitis has reversed seasonality, with more (not fewer) episodes occurring during the warmer months. Many doctors tell patients with diverticulosis not to eat seeds or popcorn but recent studies show consuming seeds and nuts are not involved one way or the other in developing diverticulitis.
This month, Doctor Lillias Maguire, working under senior author Professor Andrew Chan, both of Massachusetts General Hospital, studied vitamin D levels in people with both diverticulosis and diverticulitis to see if 25(OH)D levels were different in patients who went on to develop diverticulitis.
They studied more than 9000 patients with uncomplicated diverticulosis and 922 patients who developed diverticulitis that required hospitalization. Among patients with uncomplicated diverticulosis, the mean 25(OH)D was 29 ng/mL compared with 25 ng/mL among the 922 patients with diverticulitis that required hospitalization (p<.0001). They collected the blood prior to hospitalizations for diverticulitis, minimizing the likelihood diverticular disease resulted in low vitamin D levels.
The mean level was 23.5 ng/mL (p<.0001) for patients who developed recurrent diverticulitis. Compared to patients in the lowest 25(OH)D quintile, the odds ratio for developing diverticulitis were .45 among patients in the highest 25(OH)D quintile (P <0.0001). That is, those with the lower levels were about twice as likely to need hospitalization.
The authors concluded:
“In summary, we show that higher pre-diagnostic serum 25(OH)D levels are associated with a lower risk of requiring hospitalization for diverticulitis. Taken together with prior studies showing an inverse association of 25(OH)D and risk of colorectal cancer and inflammatory bowel disease, these results highlight the potential importance of vitamin D in the maintenance of colonic health. Additional studies in cohorts with more detailed information on potential confounders of this association are warranted.”