OBESITY: Gut microbes may have something to do with weight changes.
OBESITY: Gut microbes may have something to do with weight changes. Thinkstock

LETTER: We’re making ourselves sicker

I OFTEN write about the importance of species diversity and abundance for healthy ecosystems. All of us have our own personal ecosystem, including a hundred trillion microbes made up of thousands of different species living in and on our body.

Just one drop of fluid from your colon contains more than one billion bacteria and these microbial cells outnumber our own cells 10 to one, making us in some ways, more microbe than human.

We have decimated the bacterial populations inside our bodies through overuse of antibiotics, processed food, chlorinated water, hormones, pesticides and an utter fixation with cleanliness. We are actually making ourselves sicker.

Our diet changes our gut bacteria. We can make skinny mice fat by inoculating them with the gut bacteria from obese mice. Do you know somebody who is packing on the kilos despite eating an identical diet to someone who has a normal weight? There may well be a secondary reason for this and that reason may be an altered ratio of their gut bacteria.

Obesity has increased exponentially over the past few decades. I am convinced that weight gain is more complicated than simply energy in versus energy out. Obese humans have higher populations of gut bacteria that are more efficient at extracting nutrients.

These people therefore absorb more calories from their food and the result is more weight gain. Obviously diet and exercise are important factors, but I am convinced that our gut microbes, not our genes are inextricably linked to weight changes.

So how does our internal ecosystem or microbiome get out of whack? Our gut bacteria are determined by the food we eat. The western diet full of sugar, saturated fats, artificial sweeteners and starches send our gut bacteria into a feeding frenzy that promote the growth of the wrong bacterial species.

Also, for the past 50 years we have been feeding antibiotics to the animals we eat because antibiotic-fed animals gain weight faster and this increases profit.

It also increases our waistline when we eat antibiotic-fed animals because the antibiotics selectively augment the growth of bacterial species that extract more energy from food, as I mentioned earlier. Baby mice given low-dose antibiotics early in life, even for just a few weeks, makes them obese in later life. Many other simple choices we make also affect our microbiome.

We can restore the balance to our internal ecosystem, but I will need to discuss that in another letter. It's a jungle in there.

GEOFF CASTLE, Toowoomba


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