OUR INTERVIEW WITH PROF DENISE ROBERTSON
Professor Denise Robertson is a Professor of Nutritional Physiology at the University of Surrey and a deputy editor of the British Journal of Nutrition. Her research interests include gastrointestinal physiology, dietary fibre, resistant starch and nutritional interventions targeting type 2 diabetes. Some of her recent publications have explored the benefits of adopting time-restricted feeding, especially among individuals who are obese or diagnosed with diabetes. We spoke with her to learn more about her career and some of her current areas of research...
1) Congratulations on recently being promoted to Professor of Nutritional Physiology at the University of Surrey! Could you give us a brief overview of your professional journey so far and what you enjoy about working in academia?
My first degree is in zoology, which people sometimes think is strange but in reality it’s very little to do with “zoos” and more to do with animal biology, of course including humans. At undergraduate level I did no nutrition at all but went on to the Human Nutrition Research Centre to do a PhD with Prof John Mathers as they had a project looking at starch and the way it was metabolised by the colon, and it just caught my interest. My first degree is in zoology, which people sometimes think is strange but in reality it’s very little to do with “zoos” and more to do with animal biology, of course including humans. At undergraduate level I did no nutrition at all but went on to the Human Nutrition Research Centre to do a PhD with Prof John Mathers as they had a project looking at starch and the way it was metabolised by the colon, and it just caught my interest.
2) One of your research interests is looking at diet and type 2 diabetes prevention and treatment. Could you tell us about some of your research into this, particularly looking at dietary fibre?
I think it has always been known that fibre would be a useful nutrient in terms of type 2 diabetes, but then it was conveniently forgotten as research focused on other things. With the importance of the gut microbiome now taking centre stage, fibre has come to the fore front again. We know that the metabolism of fibre to short-chain fatty acids by the bacteria is a key part of their metabolic effect but more is being discovered about the direct interactions with the gut barrier, which could link fibre with other metabolic diseases such as NAFLD. Fibre improves insulin sensitivity, and in some groups, the effect size can be as large as found with some medications.
3) The average UK adult consumes significantly less fibre than the recommended 30 grams per day; what might be some effective ways to increase fibre in the diet, especially for those who are reluctant to commit to major lifestyle changes?
Sometimes it’s a case of little nudges, rather than a massive change in diet. When I have given talks to patient groups before, we often show easy swaps that can be made, and how a simple lunch such as baked beans on toast can provide a large portion of our dietary fibre requirement. One of the supermarkets is doing a campaign at the moment asking people to swap half the meat in their dish for a legume such as chickpeas. Many people are not ready to make plant-based proteins the main component to their meals, but swapping a proportion is a good way to increase fibre.
4) Another of your research areas of interest is time-restricted feeding (TRF) and its influence on metabolic health. Could you explain the difference between intermittent fasting and time-restricted feeding (TRF)?
Time-restricted feeding falls under the umbrella of intermittent fasting, but it’s actually something we all do anyway, because we all stop eating at some point in the day. Traditionally intermittent fasting would involve very low energy intake over more prolonged periods, typically 36-48 hours, the common 5:2 diet. Five days of normal/healthy eating interspaced by two days of 500-600 calorie intakes. Time-restricted feeding refers to the length of the overnight fast and extending this by either delaying breakfast or bringing forward dinner, or by doing a bit of both.
5) In a recent publication within Appetite, titled ‘Identification of factors influencing motivation to undertake time-restricted feeding in humans’, you mentioned the term ‘chrono-nutrition’. Could you explain what this term means and why it has gained relevance in recent years?
Chrononutrition refers to timing eating with circadian phases, it's been known for a long time, for example, that glucose and lipid tolerance to the same food varies throughout the day, this has become much more of an issue with our current 24/7 society and shift workers.
6) Based on your research on TRF, what are some of the recent findings with regards to TRF and symptoms associated with type two diabetes? Do the current findings suggest that it is beneficial to health? Furthermore, are there certain groups of people, other than those with type two diabetes, that are more likely to benefit from changing their meal times?
This is very much an emerging field, you can tell that by the number of reviews outnumbering the number of original articles! I think at the moment it is really too early to come to any firm conclusions. Time-restricted feeding is likely to involve a change in the amount of food eaten, in addition to meal timings, especially with studies involving a very small eating window. We have studies ongoing in this area, involving both TRF and whether the location of the eating window within the 24-period is of importance.
7) What’s your opinion on the use of gut-microbiota targeted approaches (e.g. probiotics and prebiotics) in the prevention and management of type 2 diabetes?
I recently wrote a review on this, as there have been a lot of papers published in recent years. I think this could be summarised in that it has potential, but at the moment taking a prebiotic fibre doesn’t seem to give an added advantage over fibre in general. The problem arises that studies looking at pre- and pro-biotics almost never examine any changes to the microbiota, and so it is difficult to establish cause and effect.
8) You have looked at resistant starches in chilled and reheated foods and found a significant reduction in the glycaemic response after consuming these foods when compared to their freshly made counterparts. What, if any, are the implications for chilled/ready-to-eat meals that are found in supermarkets? Are there any studies that have investigated [the effect of RS in] these meals specifically? If not, do you think it would be worth investigating as these foods are widely consumed and are often high in starches?
I think the implication is that starch is not starch, and food labelling becomes problematic! Processed and ready-meals are often demonised but evidence suggests that certainly in terms of glycaemia, it may not all be bad news. I am not aware of anyone having looked at ready meals specifically. Often there is difficulty establishing the provenance of the food we purchase, chilling of food is very common during transport and so some food we buy at room temperature may still have been chilled.
9) Continuing on the topic of resistant starches, does consuming certain resistant starches (eg. Resistant Starch 3, known as RS3 starch) impact the gut microbiota differently when compared to the freshly cooked version?
There has been much less work on type 3 resistant starch, but in general, we know that all fibres affect the microbiota in unique ways, indeed type 2 resistant starches from different botanical sources may have different effects.
10) Since you are an active user of Twitter, could you share some tips for those looking to better utilise social media as a professional networking tool?
Twitter can be an interesting place! In terms of social networking, it's good to follow accounts from people who do not agree 100% with your point of view, but there are quite some extreme opinions on there. I tend to follow lots of professional accounts, organisations, charities and avoid anyone whose avatar is a man with his shirt off!