Most of us probably don't have a clue if our gut microbes are healthy or not, let alone what our gut microbes actually are. However, gut health has now become one of modern medicine’s big areas of interest.

Our gut microbes are the trillions of bacteria in our gut that play a vital role in managing everything from how we sleep, to our moods and mental health ... and even how much weight we lose or gain.

Actor Catherine Tyldesley had her own gut microbes tested for the TONIGHT programme five years ago. She looks at the impact on her life - and what the latest research might mean for the rest of us.

Catherine speaks to Professor Tim Spector of King's College, one of the world’s foremost experts in nutrition and the gut, he helps dispel the myths around what is and isn't good for our gut.

There is an obsession at the moment, that you need protein bars, you need protein shakes everyone needs protein, and unless you’re an elite athlete, you don’t need more protein than the average person. Most people think of meat, so they overdo the meat and sometimes, that helps some people lose weight, short term, but long term it causes major problems, because you’re not getting the diversity that your microbes need to really flourish.

Professor Tim Spector, KCL
A range of health foods available from your local supermarket - but are some better for your gut than others?

One way people sometimes try to improve the health of their gut is by buying products that contain live bacteria. But Tonight found that some supermarket products containing live bacteria also contain a lot of sugar; with more than half the recommended daily amount found in one serving of a yoghurt drink. In other products the bacteria has actually been killed off by the pasteurisation process, so will no longer be live.

There are plenty of pills and supplements on the market that also offer to give your gut bacteria a boost. Catherine gets advice on these products from pharmaceuticals expert Professor Simon Gaisford.

When you start asking questions about bacteria in your colon for instance, you can have upwards of six to ten thousand different species. And so, to say this one, is doing something, is really difficult. And that's why I think the consumer should try a range of different products, and see what works best for them.

Professor Simon Gaisford, UCL School of Pharmacy

A recent study has shown that as little as one course of antibiotics can cause an imbalance in the gut bacteria to occur. Most people will recover with time, but if you are trying to improve your gut health there are some things you can do to help…

DOs & DON’Ts


  • Include a diverse range of plant-based foods in your diet.

  • Eat food that contains polyphenols. These are the chemicals in brightly coloured fruit and vegetables like berries, but are also found in dark chocolate and red wine.

  • Consume fermented foods containing live microbes on a regular basis.


  • Eat ultra processed food like crisps, sweets and fizzy drinks on a regular basis

  • Eat food containing artificial sweeteners

  • Snack between meals. Your gut microbes like having a rest.

For more information, watch Tonight's 'Diet: Trust Your Gut' with Cath Tyldesley at 7:30pm on ITV.