Your wellbeing is at the heart of everything we do at OptiBac. We are the UK’s experts in good bacteria and our supplements are developed in the world’s leading laboratories.

All scientific content on the OptiBac website is written by highly qualified microbiologists, nutritionists and nutritional therapists. Our team of expert writers are here to guide you through all things friendly bacteria, provide expert nutritional advice and keep you up-to-date with the latest news, scientific findings and insights about gut health and the microbiome.

Meet the team behind our blogs, FAQs and articles.

Dr Kate Stephens

PhD (Food and Microbial Sciences)
BSc(Hons) Medical Microbiology


Kate gained a PhD from University of Reading in the microbiome research unit studying microbiology, Molecular biology, Biochemistry, Human physiology and Immunology. The topic of her PhD thesis was ‘Synthesis and cholesterol lowering abilities of novel prebiotics produced using probiotic organisms’. This involved being highly skilled at exploring research, doing clinical trial analysis and scientific review writing.

Fun fact: Kate genuinely thinks bacteria are cooler than people! Much more advanced and ahead of the game.

Ben Hook

BSc (Hons) Nutrition ANutr – Nutritionist


Ben studied Nutrition at Oxford Brookes University after deciding to specialise after 8 years being a Personal Trainer. He researched intermittent fasting in comparison to traditional restriction diets to aid in weight loss as his thesis and he still have a keen interest in sport and exercise nutrition.

Fun fact: Ben believes that brightly coloured food should be consumed in a varied diet. So much so he often wears a coat in the office to have his beetroot containing salads at lunch to avoid splashes.

Christina Georgallou

BSc. Physiology NT Dip. CNM


Christina is a creative spirit, specialised in Nutritional Therapy, with a keen interest in understanding how our bodies work with the aid of the microbial world within.

Dr Sasivimol Ahmed

Sasivimol Ahmed PhD, PG Dip (Personalised Nutrition), BSc (Food Science)


Sasivimol is a registered nutritional therapist (rCNHC, mBANT) with a special interest in gut health. She also has a Food Science degree and earned a PhD in Biotechnology from University of Reading. Her PhD research focused mainly on Bacillus fermentation. She is passionate about functional food. In her previous academic career, she got involved in research on prebiotic and probiotic foods.

She lives in Reading, Berkshire where she also practises nutritional therapy. She loves yoga and step aerobics as well as enjoys reading food magazine, writing nutrition articles and cooking healthy foods.

Joanna Scott-Lutyens

BA (hons), DipION FdSc


Joanna has been studying or working in the area of health now for around 10 years. She has great experience in clinical work as a nutritional therapist, organisational work on the NHS and now presently in education and research within the private sector. She is passionate about all areas of health, giving people the best chance to be healthy and well in life, and passing on information, research and health education where she can.

Katie Wheaton

Katie is a registered nutritional therapist, DIP NT, (B.A.N.T) (CNHC) and director of Katie's Mindful Kitchen. She is also a certified DNA life practitioner in the area of nutrigenomics which looks at the effects of nutrients on the regulation of gene expression.

Katie uses a combination of Nutritional Therapy and Functional Medicine (which combines nutrition and health science) to support optimum health, as well as the traditional practices of naturopathic nutrition. She has been in clinical practice for three years, with a special interest in gut health.

Alongside her nutrition programmes she works as a plant based chef bringing delicious, nourishing, balanced meals to retreats, events, and workshops.

Katie loves feeding her gut bacteria with a diverse rainbow diet and believes that 'your microbiome has your back!', so it's important to eat with them in mind.

Kerry Beeson

Kerry is a fully qualified nutritional therapist, having studied Nutritional Medicine at the University of West London; her training encompasses naturopathy, nutritional therapy, functional medicine, and kinesiology. She is also a trained Metabolic Balance Coach.

Kerry leads a team of Nutritional Advisors at OptiBac Probiotics where she specialises in microbiome support, and spends most of her days talking about vaginas and bowel movements. She is also very creative, with a background in art and music, but her favourite form of creative expression is writing: she has been contributing to both mainstream and health industry publications for years, and is also the Content Editor at OptiBac Probiotics.

She loves being out in nature and keeps fit by walking, making intermittent visits to the gym, and tidying up after her teenage daughter. When the weather’s bad you’ll find her indoors writing something, or reading about nutrition, ancient history and fringe science with a cat on her lap.

Megan Crowch

BSc (Hons) Physiology, Dip Herbal Medicine, Dip Naturopathy

Megan has been with OptiBac for 6 ½ years now in a technical capacity, alongside this she is a herbal medicine practitioner. Prior to this she had 3+ years’ experience working in a clinical research organisation, and a few years working in health shops whilst training as a herbalist.

Megan loves preparing and eating good food, walking her dog and ducking into hedgerows to see what herbs are growing there. Making sure she’s chilling out to rest her gut-brain axis.

Laura Ryan

BSc (Hons) Psychology, DipCNM NT, mBANT, CNHC
Dip CNM Naturopathic Nutritional Therapy
BSc Psychology (Hons)


Laura has been a part of the OptiBac Probiotics team for nearly 5 years; She started as a sales rep in London while studying nutritional therapy at CNM and then moved into the ‘Technical team’ where she’s been for over 3 years now. Her job keeps her up to date with research developments on the human microbiome, it also lets Laura put her creativity to good use when working on new products and training materials. It’s a very exciting time for this industry, with all the scientific discoveries being made.

Laura’s key interest is women’s health and mental health because it affects us all. She studied psychology and nutritional therapy, so she’s excited to see research on the gut brain axis reveal more and more about the role of bacteria in our behaviour and mood.

Kathy Wheddon

Nutritional Therapist DipION


Kathy qualified as a Nutritional Therapist from ION in 2005.

She has worked part time as a Nutritional Therapist ever since, but the amount of time she has dedicated to it has fluctuated a lot over the years, depending on where else she is working. Nowadays, Kathy sees occasional clients, as and when they find her. Making sure she stays on top of the relevant knowledge within the field. In her own owns ‘If a client finds me, I feel that the universe thinks I am the right person to help them’.

She wrote her dissertation on ‘the role of antioxidants in preventing and reversing cognitive decline in later years’, however since then Kathy has become more and more interested in the role of nutrition in preventing cancer and supporting cancer patients, she has attended several seminars and CPD lectures on this topic. She holds the absolute belief that if we give our body the support and nutrition it needs, we can overcome or at least improve most health challenges.

Fun fact: I am a complete supplement junkie, and take 17 different ones a day, spending most of my wages on them!

Lifestyle team

Jacob Collyer-Smith

Jacob is a long standing member of the OptiBac Probiotics team. He has a fascination in emerging science around friendly bacteria. In his spare time he is a keen runner, loves a long dog walk in the countryside, and has recently started bouldering & climbing this year.

Sam Ter Haar

Sam is our video, photograph and graphic design whizz at OptiBac. His passion for good food and great holidays always mean he’s the best person to go to for a recommendation. Sam is also a big film fanatic, and is always free for a session of bouldering.

Penny Archer

Penny is one of the creatives in the Brand team at OptiBac. She has an interest in learning more about how we can all help prevent potential health problems of the future with the power of nutrition. In her spare time she enjoys running, loves to be by the sea or hiking in the countryside.