Low BMI after 19 can lead to inflammatory bowel disease later in life

DELHI: A population-based cohort study of 377,957 men has found a significant association between underweight in young adulthood and later risk of inflammatory bowel disease (IBD) particularly Crohn’s disease (CD).

Inflammatory bowel disease (IBD) is an umbrella term used to describe disorders that involve chronic inflammation of the digestive tract namely ulcerative colitis and Crohn's disease.

The study, published in the journal Scientific Reports found that low body mass index (BMI) of men entering adult life is associated with an increased incidence of CD and ulcerative colitis (UC) up to 40 years later.

BMI is associated with increased future risk of IBD particularly CD, where associations with high and low BMI have been observed. Most studies are based on adult women. Michael A. Mendall, Gastroenterology, Croydon University Hospital, Surrey, UK, and colleagues aimed to explore the impact of BMI in men entering adult life on their long-term risk of developing IBD.

The researcher used data from 377,957 men born from 1939 to 1959. BMI was measured at draft boards (mean age, 19 years) with men followed from 1977 (or time of examination) through 2015.

Key findings of the study include:

• During 13 million person-years of follow-up, 1,523 men developed CD and 3,323 developed UC.


• Compared with men of normal weight, the risk for CD was as follows: hazard ratio, 1.35 for BMI <18.5 kg/m²; hazard ratio, 0.83 for BMI 25 to 29.9 kg/m²; and hazard ratio, 1.20 for BMI >30 kg/m².


• Until age 60 years, the increased risk for CD in underweight was maintained and was not explained by known effects of smoking.


• For UC, minor inverse associations were observed.


• Restricted cubic splines revealed a U-shape association between BMI and CD, but not UC.

"In conclusion, our population-based cohort study of 377,957 men followed from age 19 showed a U shaped association between BMI and risk of CD with a significant association between underweight in young adulthood and later risk of CD, which persisted long-term, wrote the authors.

For detailed study log on to https://doi.org/10.1038/s41598-019-42642-8