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Quiz: How Well Do You Know Your Gut Microbiome?

Test your knowledge of the trillions of microscopic organisms living in your colon — and the role they play in brain health

By

Christine Richmond

 
Updated June 03, 2025
Updated June 03, 2025
A man and woman with illustrations of their intestines with colorful bacteria on their stomachs
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Question 1 of 8

True or false? The bacteria in your body outnumber your own cells 10 to one.

This widely ​​cited data was officially debunked in a 2016 paper in PLoS Biology, which estimated the adult human cell count closer to ​​30 trillion and our bacterial cell count at about 38 trillion.

Question 2 of 8

The gut microbiome has been linked to which aspects of brain health?

It's hard to believe that the tiny microbes in your gut could influence so much, but ​​research has found that the gut microbiome impacts the brain from the beginning of life onward.

Question 3 of 8

Which of the following substances is NOT produced in the gut?

Many compounds that are vital to your health are made in your gut. This includes the natural mood booster ​​serotonin; ​​short-chain fatty acids, which​ are ​important for ​metabolism; and ​​vitamin K, essential for blood clotting and bone health. But food is your only source of ​vitamin C.

Question 4 of 8

Which of these can change the composition of your gut microbiome?

The composition of your gut microbiome is shaped by many lifestyle factors, including what you eat, the prescriptions you take and ​maybe even ​​​​​the pets in ​your ​house.

Question 5 of 8

What do experts recommend eating more of to benefit the gut microbiome?

Much of the fiber in the food you eat reaches your colon undigested and gets broken down by your gut microbes, resulting in the production of beneficial short-chain fatty acids. There’s evidence that eating more dietary fiber can improve the diversity of your gut microbiome, too, which is a good thing.

Question 6 of 8

During what stage of life do our gut microbiomes change the most?

Although your gut microbiome is always fluctuating in response to your diet, your environment and even the amount of ​​sunlight you get, ​​evidence suggests it changes the most in the first two to three years of life.

Question 7 of 8

Which of the following is a good option for restoring gut microbiome balance after taking antibiotics?

Your best bet is eating ​fermented foods like sauerkraut or kimchi, which provide naturally ​​occurring beneficial bacteria. Research suggests probiotic supplements are often ineffective and may even delay recovery.

Question 8 of 8

True or false? Modern life is making our gut microbiomes less diverse.

People living in industrialized areas tend to have less diverse gut microbiomes, according to a growing body of ​​research. This is likely due to a combination of factors, including less time spent outdoors and a ​low-fiber ​Western diet high in fat and sugar​.​

You have unanswered questions. Please go back and complete those questions to finish the quiz.

To learn more about your gut microbiome and its close relationship with your brain, visit Staying Sharp.

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