People who were breastfed are at lower risk of developing inflammatory bowel disease than those who weren’t, Massachusetts General Hospital researchers reported.
The team said the protective effects applied to people across the globe.
Their work, based on an analysis of previously published studies, supported research suggesting that breastfeeding helps ward off bowel disease. Some studies have contradicted this notion.
The Boston researchers reviewed 35 studies involving 15,000 patients that looked at the link between breastfeeding and bowel disease between 1961 and 2016. The team’s work, published in the journal Alimentary Pharmacology & Therapeutics, was titled “Systematic review with meta-analysis: breastfeeding and the risk of Crohn’s disease and ulcerative colitis.”
Only two of the studies followed participants over time. The others involved a case-control approach. This involves comparing rates of disease between people who report they were breastfed with rates of those who said they were not.
The research included children and adults with Crohn’s disease and ulcerative colitis. Half the studies were from Europe, with studies from North America and the Asia-Pacific region making up about a fourth of the total each.
Participants included 7,536 people with Crohn’s disease, 7,353 with ulcerative colitis, and 330,222 controls.
The Massachusetts General researchers found that being breastfed reduced the risk of developing a bowel disease by 26 percent. Looking at the conditions separately, breastfeeding reduced the risk of ulcerative colitis by 22 percent and of Crohn’s by 29 percent.
Another finding was that the risk of a non-breastfed person developing a bowel disease as an adult was the same as it was of them developing it as a child. The different breastfeeding methods used in the studies did not appear to influence the result, the researchers added.
Although breastfeeding lowered the risk of developing a bowel disease in all populations, people from Asia appeared to benefit most, the team said. Asians were at 69 percent less risk of developing Crohn’s if they had been breastfed. Their risk of ulcerative colitis was also lower.
The longer a child was breastfed, the more protective the effect, the analysis showed. The risk of a person developing Crohn’s disease was 38 percent less after three months of breastfeeding than a non-breastfeeder. The risk was 80 percent lower when a person was breastfed for a year.
Similar numbers applied to the risk of developing ulcerative colitis. After 12 months of breastfeeding, the risk dropped by 79 percent, compared with 37 percent after three months.
Researchers acknowledged that the study had limitations. To start with, results of the individual studies varied widely. Another glitch was that studies relied on people remembering how long they were breastfed — a well-known source of error.
Moreover, most participants were Caucasian. There were five studies of Asians and one of Hispanics.
Nonetheless, the researchers argued that their study provided enough evidence to recommend breastfeeding as a way of reducing infants’ risk of developing a bowel disease later.