CHICAGO – , according to a lecture delivered at Freston Conference 2019, sponsored by the American Gastroenterological Association.
Although the literature is highly consistent, it contains discordant findings, and many questions remain unanswered. “We need more rigorous studies, and particularly more interventions, to truly understand the role diet may play in patients with IBD,” said Ashwin N. Ananthakrishnan, MD, MPH, associate professor of medicine at Massachusetts General Hospital in Boston.
Food can cause symptoms in IBD
Many patients with IBD are convinced that their diet caused their disease. A relevant point for physicians to consider is that these patients are at least as likely as is the general population to have intolerance or sensitivity to food components such as lactose and gluten. In a prospective questionnaire of 400 consecutive patients with IBD in the United Kingdom, 48% expressed the belief that diet could initiate IBD, and 57% said that diet could trigger a flare-up. In addition, 60% of respondents reported worsening of symptoms after eating certain foods, and about two-thirds deprived themselves of their favorite foods to prevent relapses (Inflamm Bowel Dis. 2016;22:164-70). A French study found similar results. “Clearly there’s something there,” said Dr. Ananthakrishnan. Patients’ beliefs about the relationship between food and their symptoms are not simply misconceptions, he added.
A Canadian study published in 2016 found that almost one-third of patients with IBD avoid many food groups. “But there is significant heterogeneity in the foods that are avoided, and sometimes we mistake this heterogeneity for a lack of association between diet and symptoms in IBD,” said Dr. Ananthakrishnan. A larger number of patients avoid certain foods during periods of active disease, which suggests that food exacerbates their symptoms, he added. The same study showed that patients with IBD have more restrictive diets than do community controls. Patients eat fewer fruits and vegetables and generally consume less iron-rich food and less protein-rich food than healthy controls. GI intolerance, rather than professional advice, is the most common reason that patients with IBD restrict their diets (JPEN J Parenter Enteral Nutr. 2016;40:405-11.).
A cross-sectional survey of 130 patients with IBD and 70 controls yielded similar results. Among patients, GI symptoms that resulted from consuming foods were not related to disease activity, disease location, or prior surgery. Patients with IBD tended to have greater frequency of GI intolerance to foods than did controls (Scand J Gastroenterol. 1997;32:569-71.).
Diet may cause intestinal inflammation
International research has recorded increases in the consumption of sugar and fat (particularly saturated fat) and concomitant decreases in fiber consumption during the past several decades. The incidence of IBD has increased in parallel with these dietary changes with a remarkably similar trajectory, said Dr. Ananthakrishnan. The correlation between dietary changes and IBD incidence “holds true even more strikingly in countries that are now experiencing Westernization,” he added. These countries have undergone more rapid dietary changes, and their IBD incidence has doubled or tripled. The transition to “less traditional diets” appears to promote intestinal inflammation, said Dr. Ananthakrishnan.