乌鸦传媒

Incorporating diet into Crohn's disease (CD) treatment regimens has some support, with a shift toward a whole-foods nutrition approach for symptom relief and healing.

Although far from definitively established, inflammation is a potential mechanism through which diet may modulate the onset of CD.

"There's some evidence that certain dietary components may increase the risk of developing CD, but it's less clear whether diet has any impact on flareups of existing disease," said Linda A. Feagins, MD, of Dell Medical School at the University of Texas at Austin. "The studies on diet are mainly retrospective, so we have to take the data with a grain of salt."

While no specific food or environmental factor is known to directly cause inflammatory bowel disease or induce flares, of three large prospective health professional cohorts found that people with diets high in inflammatory potential had a heightened risk of developing CD.

Specifically, compared with participants in the lowest quartile of cumulative average empirical dietary inflammatory pattern (EDIP) score, those in the highest quartile had a 51% higher risk of CD (HR 1.51, 95% CI 1.10-2.07, P=0.01 for trend). Compared with participants with persistently low EDIP scores, those who shifted from a low- to a high-inflammatory potential diet or persistently consumed a pro-inflammatory diet had greater risk of CD (HR 2.05, 95% CI 1.10-3.79, and HR 1.77, 95% CI 1.10-2.84).

Components in typical Western diets especially have been proposed as CD triggers, with dietary antigens inducing changes in the gut microbiome that lead to flora dysbiosis, altered host homeostasis, and dysregulated .

These potentially harmful aspects of the Western diet include higher intakes of red and processed meats, ultra-processed convenience foods, sugar, and refined grains. Other features are greater consumption of unhealthy fats, such as saturated and trans fats and omega-6 polyunsaturated fatty acids, as well as exposure to commercial food additives and emulsifiers such as carrageenan and additive-associated .

"The data on food additives come mainly from animal studies, although there are some small human data suggesting they may play a role," Feagins said.

In contrast, reduced risk has been associated with the Mediterranean diet's higher intakes of fiber and the omega-3 polyunsaturated fats found in fish, nuts, seeds, and avocados. Individuals can readily make beneficial changes by following a high-fiber Mediterranean diet, Ashwin Ananthakrishnan, MD, MBBS, MPH, of Massachusetts General Hospital and Harvard Medical School in Boston, told 乌鸦传媒.

While most physicians agree that maintaining good nutrition is essential in CD, it's less clear what the best way to do that is. In terms of maintenance, high-quality data on diet are limited, with studies to identify dietary triggers of relapse yielding mixed results. Nutritional therapies remain underutilized by many gastroenterologists, and randomized controlled trials are lacking for most .

Moreover, diet is clinically challenging to integrate into management, said Ananthakrishnan. "Dietary strategies require a lot of patient commitment and motivation for sustained adherence, and partial adherence is less effective than full adherence."

In addition, relying on fresh, high-quality home-cooked food is expensive and time-intensive. "This may not be possible for everybody," he added. "Children, adolescents, and college-going young adults have limited control over their food quality and preparation methods. This makes diet challenging without an adequate buy-in from the whole family."

Other Regimens

Whole-foods dietary patterns aside, dietary interventions with benefit tested in randomized controlled trials include or the , Ananthakrishnan said.

An in 74 children, for example, found that combining a CD exclusion diet with 50% of calories from enteral nutrition induced sustained remission in a significantly higher proportion of patients than did exclusive enteral nutrition. It also produced remission-associated changes in the fecal microbiome. At week 12, after dropping to 25% enteral nutrition with either the CD exclusion diet or a free diet, corticosteroid-free remission rates were 75.6% and 45.1%, respectively (OR 3.77).

"A number of other exclusion diets, including the specific carbohydrate diet, have also shown benefit in reducing CD symptoms," said Ananthakrishnan. "But ensuring adequate soluble fiber from fruits and vegetables, minimizing processed foods and red meat intake, and reducing sugar-sweetened beverages appear to be beneficial. In general, it's important to combine dietary therapy with pharmacologic therapy to ensure maximal benefit to the CD patient."

But are gastroenterologists routinely recommending that approach? "There are no published data on physicians' practices, but my perception is that more doctors, especially at academic centers, are at least starting to see that diet plays a role," Feagins said. "But there's still a set of physicians and an older dogma that says diet has no role."

The challenge in recommending any diet is that the disease and people's eating preferences are both heterogeneous, she added. "And doctors rarely have the information to recommend which diet to which patients."

Ananthakrishnan agreed: "Historically gastroenterologists, and even nutritionists, have received inadequate training in the role of diet in CD. But this is changing with growing data and training programs to address this."

In the current clinical setting, if a patient has active disease and is starting a new therapy, Feagins often encourages synergizing treatment with a Mediterranean-type diet. "And if CD is under control and the patient is on optimal medications with no active disease but begins to experience symptoms of irritable bowel syndrome [IBS] on top of CD, I'll look at the IBS spectrum and maybe advise a trial of a low-FODMAP [fermentable oligo-, di-, and monosaccharides and polyols] diet," she said.

As for potentially anti-inflammatory supplements such as fish oil and turmeric, "I don't recommend these routinely but I don't have a problem if a patient wants to take them," said Feagins. "And there is some evidence that turmeric helps in [ulcerative colitis]."

Given the the danger of macro- and micronutrient deficiencies with specialized diets, gastroenterologists should consider enlisting registered dietitians to optimize nutrition in the inpatient and outpatient settings. All CD patients should be screened for malnutrition, said Feagins. "This is something we do at least yearly if not more often in my clinic. There's a very simple screener that has two questions to do this. This helps me decide who needs to see the dietitian sooner than later."

Comment