Childhood obesity is a growing problem not just in the United States, but around the globe. While diet and exercise are basic ways to reduce weight, there can be many complex causes of weight gain. Stress, caloric intake and genetics have all been seen to have a correlation with weight gain. Recent studies, however, have suggested a possible microbiome connection, through a correlation between obesity and the antibiotic exposure. A recent review published in Advances in Obesity, weight management & control described various studies on this subject.
The researchers discussed five studies that were related to childhood obesity and antibiotic intake. In a Canadian study of 616 children participating in a Study of Asthma, Genes and the Environment survey, a significant relationship was found, particularly for boys, between obesity at ages 9 and 12 and first antibiotic exposure at 3-12 months. In the UK, the Avon Longitudinal Study of Parents and Children found that antibiotic prescription before 6 months of age led to higher Body Mass Index during 10 to 38 months, while later antibiotic intake did not lead to this association. In a study done by Bailey with 65,480 children, 69% of children had infant or preadolescent obesity if they had taken antibiotics during the first 23 months of their life.
In a fourth study discussed by the article, a large cross sectional study ISSAC was performed in New Zealand on 74,946 male children between the ages of 5 and 8. The study found that boys who had taken antibiotics during their first year of life had higher BMIs later in life. Finally, in a Danish study by Ajslev, 28,364 children were administered antibiotics before 6 months of age and were followed up for the next 7 years. A significant association between antibiotics and obesity was found only for boys.
Based on these studies, it seems apparent that altering the microbiome through antibiotic use early in life is associated with an increase in BMI. As many people have recognized in recent years, farmers give antibiotics to their livestock to help them gain weight, and a similar phenomenon may be occurring in humans. Scientists like the AMI’s advisory board member Martin Blaser have taken up this cause, and he has lectured about this connection many times in recent years. We know that the microbiome impacts weight gain through diet and nutrition, so it should come as no surprise that decreasing the abundance of many bacterial species through antibiotics may cause obesity.