You're doing a lot of things right. But some things hiding in plain sight might be undoing your efforts.
In the final part of this series, Ruth Sharif, KURK’s resident nutritional therapist, covers the smoothie mistakes most people make, the artificial sweetener issue she finds genuinely upsetting, and the thing that surprises clients most: how quickly the gut can actually change.
Missed the earlier parts? Start with Part 1: why everything comes back to your gut or Part 2: the fibre gap and how to fix it.
Are smoothies actually good for gut health?
Smoothies come up with clients constantly. Ruth is broadly positive, but with some important nuance.
"Smoothies are generally better than juices a lot of the time, because you're keeping some of the fibre intact."
The issue is blood sugar. "Smoothies that have a lot of fruit in them can be quite challenging in terms of blood sugar balance. And if there's any imbalance in your gut bacteria, that's quite a lot of sugar to put in in one go."
Her fix: make smoothies predominantly vegetable-based, include a protein source, and add something like chia seeds for a gentle blood sugar buffer.
The artificial sweetener problem no one's talking about
This one clearly bothers Ruth. She raises it unprompted and with feeling.
"Some artificial sweeteners can actually impact the diversity of our gut microbiome, which is really not great, and they may still affect blood sugar responses in some individuals too."
Her specific concern is the ones hiding inside products that look healthy on the outside.
"When you're doing all this other great stuff, and then you think you're having something healthy... it makes me quite upset, actually. People just don't know because it's packaged within a healthy product."
Plant-based alternatives like stevia or monk fruit are generally better tolerated, though they won't be to everyone's taste. For most other sweeteners, Ruth would steer clients away. The takeaway: check the ingredients list, even on the products you trust.
How quickly can your gut microbiome actually change?
This is the part that genuinely surprises people, and it's the best note to end on.
Ruth runs gentle cleanse programmes with clients, and what she sees within the first few days consistently catches people off guard.
"By sort of day five, they're like, 'I just haven't even thought about sugar.' And that's how quickly your gut microbiome can actually change."
She uses this to cut through the idea that change has to be slow, complicated, or miserable.
"This doesn't need to be a long protracted programme. By just making those small changes, low and slow, you can change how you feel quite dramatically."
The word she uses for how clients feel once things start clicking: they don't want to go backwards.
Small, consistent changes. More plants. Less processed. That's the foundation. Understanding why those changes matter at a biological level is where the real shift happens, and it's exactly what KURK's Scientific Advisory Board was built to help with.
FAQs
What is the gut-brain connection? The gut and brain are linked via the vagus nerve and communicate constantly. Around 95% of the body's serotonin, a neurotransmitter involved in mood regulation, is produced in the gut. The gut microbiome also influences how neurotransmitters are produced and signalled, which is why gut health can have a significant effect on mood, focus, and mental wellbeing.
Can your gut microbiome change quickly? Yes. Ruth sees clients on gentle cleanse programmes report that sugar cravings reduce significantly within around five days. The gut microbiome is responsive to dietary change, and even small, consistent shifts, more fibre, more plant diversity, fewer processed foods, can begin to make a difference relatively quickly.
Are smoothies good for gut health? Generally yes, especially compared to juices, as they retain more fibre. The key is to avoid fruit-heavy blends that can affect blood sugar balance. Ruth recommends making smoothies predominantly vegetable-based, adding a protein source, and including chia seeds for a blood sugar buffer.
Are artificial sweeteners bad for gut health? Some artificial sweeteners can negatively affect the diversity of the gut microbiome and may affect blood sugar responses in some individuals. Ruth recommends checking ingredient labels carefully, even on products marketed as healthy. Plant-based alternatives such as stevia or monk fruit are generally better tolerated, though taste preferences vary.
Read Part 1: Why everything comes back to your gut
Read Part 2: The fibre gap and how to actually fix it
Ruth Sharif is a Registered Nutritional Therapist and Naturopath and a member of the KURK Scientific Advisory Board. She holds Diplomas in Nutritional Therapy and Naturopathy from the College of Naturopathic Medicine (2012) and is a member of BANT and registered with the CNHC.
