Crohn’s Disease CD
Research
Diet and Crohn’s Study - HMRI
Introduction
CD = Crohn’s Disease
UC = Ulcerative Colitis
IBD = Inflammatory Bowel Disease = both UC + CD
Patterns of disease
80% of patients have small bowel involvement, usually distal ileum
50% of patients have ileocolitis
20% of patients have the disease only in colon
30% have perianal disease
10% have involvement of mouth, stomach, duodenum
Incidence
Lower in Asian and Middle Eastern countries
However, the incidence is rising in newer industrialised countries in Africa, Asia, and South America
Highest rates are in Scandinavia with Sweden, Finland and Denmark at around 9 in 100 = 1 in 11
The rate in the USA at 422/100,000 = 1 in 250
Lowest rate in the Caribbean at 6/100,000 = 1 in 16,000
North / south gradient with high incidence in countries closer to the poles and lower closer to the equator
Possible link to less sunlight and lower Vitamin D
Demographics
Onset most common between 15 and 30
Bimodal with a second peak between 50 and 80 years
Slight female predominance
Risk Factors
Smoking is a risk factor for CD but not Ulcerative Colitis UC. Smoking increases the risk of complications e.g. strictures, fistulas
Physical activity decreases the risk of CD. One study showed those in the top 20% of physical activity had CD rates of 6/100,000 versus those in the bottom 20% of physical activity at 16/100,000
Diet
Fibre - particularly fruit and cruciferous vegetables decreased the risk of CD.
Fats - Total fat, animal fat, and polyunsaturated fatty acids PUFA increased the risk
Vitamin D - Low vitamin D common in CD
Sleep deprivation linked to disease flares in UC for those who slept <6 hours or >9 hours. Did not seem to modify the risk of CD
Gastroenteritis - links with acute gastroenteritis and developing CD. Population studies showed higher CD rates in patients with documented Samlnoella or Campylobacter gastroenteritis.
Medications
Antibiotic use is associated with inflammatory bowel disease IBD but unclear if causal relationship.
Anti-inflammatory NSAID use may increase the risk of IBD but the magnitude is small.
Oral contraception and Hormone Replacement Therapy HRT may increase the risk of IBD but the risk appears small
HRT relative risk RR for UC is 1.3 for HRT and 1.5 for oral contraception
A second study showed an RR of 1.7 for HRT on UC
Isotretinoin - Association but no strong evidence. May be confounded as these people often take antibiotics like Doxycycline first.
Appendicectomy - Some studies suggest a higher risk of CD but this may be due to misdiagnosis of the appendicitis which is early incipient CD. Appendicectomy may lower the risk of developing UC for patients with appendicitis or mesenteric adenitis compared to controls.
Psychological factors have been studied with inconsistent results. Stress may have a role in the exacerbation of patients with established IBD
Obesity - Unclear if associated however accumulation of intra-abdominal fat may contribute to mucosal inflammation. Anoperineal complications appear to happen earlier in patients with CD with obesity.
Nutrition
Malnutrition in IBD can lead to weight loss, growth failure, bone disease, and/or micronutrient deficiencies
Patients with active disease without undernutrition can generally eat what they want. No particular food category can broadly be linked to triggering a disease flare.
Patients with Irritable Bowel Syndrome IBS and IBD may benefit from a low FODMAP diet during flare-ups.
Lactose intolerance is common and lactose restriction can be beneficial in these patients.
Anti-oxidants - Data is not substantial enough to make a recommendation.
Prebiotics - Not enough data to make a recommendation
Fish oil - Not enough data
Clinical Features
Abdominal pain - Crampy. If ilial disease then pain is often right lower quadrant. Obstructive symptoms are common. Some patients have no symptoms of CD until obstruction.
Diarrhoea - Common. Often intermittent without gross blood. Intermittent diarrhoea with other features of IBD e.g. skin, eye, or joint suggests CD. Diarrhoea happens due to excess fluid secretion, bile salt malabsorption, steatorrhoea, and from fistulas causing bypass of portions of absorptive surface area.
Systemic - Weight loss and fever.
Transmural inflammation - Leads to
Fistulas - connections between two organs (bowel, bladder, skin, vaginal, peritoneum)
Phlegmon/abscess - a walled-off pocket
Perianal - common. Perianal pain or drainage.
Other GIT features
Mouth ulcers or gum pain
Oesophageal involvement leads to swallowing difficulties
Stomach involvement
References
Definitions, epidemiology, and risk factors for inflammatory bowel disease - Up To Date / Needs Log In
Inflammatory Bowel Disease Update - GESA 2018