The first 15 years of the 21^st century witnessed a significant increase in the prevalence of inflammatory bowel disease (IBD), diagnosed as either Crohn’s disease or ulcerative colitis. In 2015, 3 million US adults reported a diagnosis, which was an increase of 2 million US adults since 1999. Naturally, this rise boosted awareness of IBD – a condition which increases the likelihood of developing other chronic health conditions such as cardiovascular disease, respiratory disease, cancer, arthritis, kidney and liver disease. As a result, there has been more research seeking to discover potential risks factors that may precipitate this condition.

Currently, IBD is known to be more common in developed countries, urban communities, and among those who smoke and are of a lower socioeconomic class. It is known as a disease of “westernization.” Increased pollution, chemical exposure, and a standard western diet have also been linked to IBD.

More recently, there has been focused interest on specific influences during the first year of life that may be associated with an increased risk of developing IBD later in life. The vast majority of diagnoses of IBD occur between 20 and 40 years of age. However, most gastrointestinal conditions are rooted in an imbalanced gut microbiota which alter the gut immune response, so it’s only logical to look at the factors that influence this delicate environment, and these begin almost as soon as we take our first breath. Although a full understanding of the pathophysiology of IBD eludes us, the current understanding is that IBD is rooted in an inappropriate immune response to the gut microbiota in a genetically susceptible individual. Some of the greatest influences upon the microbiome are found in the first year of life.

Just this year, a population-based study published in the journal Gastroenterology sought to identify critical events at birth and within the first year of life that contributed to a diagnosis of IBD later in life. Researchers collected and analyzed data from 825 individuals with IBD and 5999 matched controls. Maternal IBD was the greatest risk factor for the offspring developing IBD, but infections in the first year of life were also significantly associated with IBD diagnoses later in life. Naturally, this raises the question of whether treatment with antibiotics, the infection itself, or a combination, is more influential in disturbing the microbiome during this critical age for its development and maturation.

Early use of antibiotics certainly impacts the developing microbiome of the infant. In a case-control analysis of a population-based IBD study, data on antibiotic use in the first year of life was examined and compared between subjects with IBD and matched controls. The results showed 58 percent of those with IBD had taken antibiotics during their first year compared to 39 percent of controls, indicating that antibiotic use early in life may raise the risks of developing IBD.

Breastfeeding is another influential factor which imparts significant protection against IBD. In a systematic review and meta-analysis of comparing the risk of developing either Crohn’s disease or ulcerative colitis with breastfeeding, data was collected from 7,536 individuals with Crohn’s disease, 7,353 with ulcerative colitis, and 330,222 controls. Any amount of breastfeeding was associated with a lower risk of developing IBD; however, those who breastfed for at least 12 months had the strongest degree of protection, compared to those who only breastfed for 3 or 6 months. Breastmilk is one of the earliest environmental influences upon the gut microbiome, impacting the intestinal microbial composition, leading to higher abundances of firmicutes and actinobacteria. Breastfeeding also influences the development of the gut immune response, helping to establish the epithelial barrier and having direct immunologic effect.

The first year of life is an essential time during which the intestinal immune system is developing. However, its development is highly dependent on the intestinal microbiota. Therefore, anything that disturbs the maturation of the microbiome during infancy can increase the risks of developing IBD. Early exposure to infections, antibiotics, and the absence of breastfeeding, which imparts both immunological and microbiome support, are perhaps some key events in an infant’s life that may contribute to the development of IBD later in life; especially if they carry a genetic predisposition for the disease.