What if your experiences as a baby – even before you were born – helped determine whether you were overweight or obese later in life? There is evidence to suggest that this may be the case, and that the prenatal environment and the first two years of life are very important in the development of overweight and obesity. Our early life environments help determine our biological make-up for the rest of our lives. Some of this programming may occur in the bacteria in our stool, also known as the microbiome.
The microbiome may be altered by many factors, including antibiotics. Multiple studies have found that children who are exposed to antibiotics in early life have a higher rate of obesity in childhood. Some researchers have linked mom’s antibiotic exposure in the second and third trimester to later obesity in her child. In a recent study of nearly 65,000 children, researchers found that children who received more than 4 courses of antibiotics before age 2 were more likely to be obese between 2 and 5 years old. Children who received antibiotics before 5 months of age were also more likely to later be obese. However, these studies should be interpreted with caution; they may miss antibiotics prescribed outside of the patient’s primary health care system, and lack data on dietary intake and physical activity. Finally they do not examine effects on children’s bacteria in their gut or their microbiome, which may be the mechanism for the relationship between antibiotics and obesity risk.
How do components of the diet impact the microbiome? We know that dietary sugars may impact the bacteria in our gut. In mice, the use of probiotics (“good” bacteria found in yogurt and other foods, which can increase the types of bacteria in the gut) prevented the metabolic changes associated with high fructose corn syrup, a common sweetener. Processed foods have also been linked to obesity and metabolic syndrome. Emulsifiers in processed foods have been shown in mice to increase their weight and risk of insulin resistance. We also know a high fat, high-carbohydrate diet has been shown to change the ratio of Firmicutes : Bacteroidetes bacteria ratio in human stools. Altering this ratio has been associated with impaired sugar and fat processing and has been linked to overweight, obesity and type II diabetes through inflammation in the gut. Experimental data indicate that inflammation is a major driver of diet-induced chronic diseases, and that the bacteria in the gut may play an important role and may have major impacts in early life.