Wednesday 7 November 2012

Unwanted side effect: obesity

Do antibiotics make us fat?

Are Antibiotics Making Us Fat? - London Student
29 Oct 2012 | News and Features
Written by Helga Groll

In the late nineteenth and early twentieth centuries, medicine was revolutionised by the discovery that microorganisms such as mould, fungi, and bacteria could produce substances capable of curing bacterial infections. In present day, a world without these substances now known as antibiotics is hard to imagine. Antibiotics are ubiquitous in everyday life, from fattening farm animals to treating infectious diseases and even certain types of cancer. Unfortunately, the overuse of antibiotics is accompanied by several side effects, the most obvious being the antibiotic resistance of certain diseases. Scientists have now discovered that the use of antibiotics during early childhood can also increase the risk of obesity.
A population study of children, done by the Avon Longitudinal Study of Parents and Children in the UK, has investigated the impact of the use of antibiotics at different points during childhood. The survey comprised approximately 12,000 children born between 1991 and 1992, and took into account the weights and lifestyles of parents and children.
Whilst exposure to antibiotics between 6 and 14 months of age did not increase the risk of obesity, a clear link between antibiotics and obesity was found when antibiotics had been administered earlier in a child’s life. After having been given antibiotics before the age of 6 months, children were seen to have been affected at 38 months. However, when antibiotics were given between the ages of 15 and 23 months, effects became apparent only after several years. By the age of 7, about 17.6% of children were overweight and 8.3% were obese.
“The composition of micro flora in the gut, ‘good gut bacteria’, is important for a healthy body, and differences in composition or lack of bacteria can be associated with inflammatory bowel diseases, metabolic disorder, immunity and obesity”, explained Professor Brendan Wren, an expert in microbial pathogenesis at the London School of Hygiene and Tropical Medicine. The gut is a microbial jungle, containing a very complex environment of microbes that stimulate vital processes such as immune responses, hormone production, energy regulation, and growth. Even the slightest change in bacterial composition can have severe consequences for the hormonal balance, or energy uptake in cells.
Dr Cormac Gahan, a microbiologist at University College Cork, adds, “There is increasing evidence in linking gut bacteria with the risk of obesity, and specific types of bacteria might play a bigger role than others. Malfunctioning bacteria can influence the efficiency of energy extraction from the diet as well as influence hormone production”.
Dr Leonardo Trasande from New York University’s School of Medicine, who is the main author of the study, thinks that the obesity is due to the composition of micro flora in the gut. Gut bacteria in children might be less stable than those in adults, rendering children more vulnerable to adverse effects from antibiotics. In addition, increased use of antibiotics in children has also been linked to dermatitis, asthma and bowel diseases.

Antibiotics could have more side effects than previously anticipated. Due to recent advances in genetic research, it is only now possible to assess the complex composition of the population of microbes in the gut. This in turn will allow more in-depth study on the development of the bacteria, and of a variety of related diseases. More research will be needed to better understand the mechanisms of how antibiotics influence gut bacteria. The indirect impact that antibiotics have on us because of the widespread use of the drug in livestock also remains to be seen. The frequency and intensity of antibiotic use should certainly come under review to ensure we can continue to use this essential medicine.

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