I’ve written previously about the alarming rise in childhood obesity in Australia (see Obesity: An intergenerational disease?), and the implications this has for quality and even length of life (see Australia is falling behind in the life expectancy race… and it’s mostly because we’re too fat).
Across the ditch, our Kiwi cousins are also fighting the battle of the bulge; they now have the third highest rate of adult obesity in the world, with Australia following closely in fifth position.
While the type and quantity of food that kids eat remains the primary influence on their weight status, there’s a growing body of evidence that exposure to antibiotics in early life may, quite literally, tip the scales toward childhood obesity.
A recently-published study titled Association of Repeated Antibiotic Exposure Up to Age 4 Years With Body Mass at Age 4.5 Years found that the more antibiotics children took in early life, the heavier they were, and that taking antibiotics in the first year of life had the most harmful effect on excessive weight gain. Furthermore, children whose mothers had taken antibiotics while pregnant with them were also heavier.
The study tracked 5128 children who were enrolled at birth into the ‘Growing Up in New Zealand‘ study, a prospective cohort study of kids born in and around Auckland in New Zealand from 2009-2010.
The researchers measured the children’s height and weight at the age of 4 1/2, and calculated their BMI. They obtained community pharmacy antibiotic dispensing data from the New Zealand Pharmaceutical Collection database for the children. They also collected information from mothers on a wide range of factors that could affect the children’s weight, including the mother’s age, pre-pregnancy weight, ethnicity, education level, socioeconomic status, diabetes before or during pregnancy, and alcohol use and antibiotic exposure during pregnancy.
When all the numbers were crunched, here’s what they found:
- By the age of 4, 95% of the children had been prescribed at least 1 course of antibiotics.
- 9% of the children were obese by the age of 4.5.
- The children’s BMI increased in a stepwise fashion with the number of antibiotic prescriptions, indicating a dose-response relationship: the more antibiotics taken, the heavier the child. Children who had received more than 9 antibiotic prescriptions had 2.4 times the odds of being obese compared to those who had never taken an antibiotic.
- Children whose mothers had taken 2 or more courses of antibiotics while pregnant with them, had a higher BMI than those whose mothers had 1 or less antibiotic exposures during pregnancy.
- Children more likely to have been prescribed antibiotics if they:
- Had also been prescribed an antireflux medication by the age of 4;
- Had been breastfed for less than 3 months;
- Had consumed 3 or more servings per day of soft drinks, snacks, and fast food at the age of 2; and
- Had mothers who were younger, less well-educated, more socioeconomically deprived and of non-European ethnicity.
As the authors state, the most likely explanation for the correlation between antibiotic use and obesity is the effect that antibiotics have on the gut microbiota. The teeming hordes of bacteria that colonise the human gut affect the harvesting, storage, and expenditure of the energy (calories/kilojoules) that we take in from our diet.
Previous studies have showed that early-life exposure to antibiotics is far more disruptive to the development of our gut microbiota than exposure later in life, and can effectively ‘program’ our weight gain trajectory:
The New Zealand study is just the latest to find a link between pre-birth and early-life exposure to antibiotics, and excessive weight gain. Studies conducted in the UK, Canada and several European have reported similar findings, indicating a ‘window of exposure’ during early childhood in which children are highly susceptible to potentially lifelong adverse consequences of antibiotics.
Despite concerted efforts to reduce inappropriate prescribing of antibiotics, 30% of children aged under 4 were prescribed at least one antibiotic in 2017.
Over one quarter of prescriptions for amoxicillin (an antibiotic which is prescribed most often to children aged 0-4) were written for upper respiratory tract infections (URTIs) such as colds and sore throats, yet the overwhelming majority of URTIs are caused by viruses, and hence will not respond to antibiotics.
Otitis media (middle ear infections) accounted for around 15% of antibiotic prescriptions, despite clinical practice guidelines that clearly tell doctors to
“Avoid the routine use of antibiotic treatment for acute otitis media”
The table below, from the Third Australian report on antimicrobial use and resistance in human health, shows data for 8 conditions for which antibiotics are not routinely recommended in guidelines, but for which doctors continue to overprescribe these drugs. Note that antibiotics are never recommended to be prescribed to a patient newly diagnosed with acute bronchitis or influenza, yet over 92% and 52% respectively of patients with these diagnoses were prescribed antibiotics by their GP:
Only 33.4% of antibiotic prescriptions written in GP practices had an explicit recorded reason for the prescription. Inappropriate prescription of antibiotics is most commonly attributed to “limited time, poor doctor–patient communication, diagnostic uncertainty and patient expectations”.
Given the potential lifelong harmful consequences of early-life antibiotic use, these do not seem to be particularly valid excuses.
It’s clear that parents and care-givers must become far more discerning consumers of health care services, both for themselves and their children.
Parents should always question whether any prescription for their child is truly indicated (i.e. in alignment with prescribing guidelines), whether alternatives to the prescription exist, and the pros and cons of each potential treatment, and what is likely to happen if their child does not take the prescribed medication.
Any doctor who becomes hostile when questioned in this fashion should be treated with suspicion and ideally, replaced with a practitioner who is happy to take the time to answer parents’ questions thoughtfully and respectfully, and to present evidence supporting their suggested treatment.
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