Our interview with Professor Philip Calder

Professor Philip Calder is Head of Human Development & Health and professor of Nutritional Immunology within Medicine at the University of Southampton and is the current president of the Federation of European Nutrition Societies (FENS). Professor Calder’s work focusses on exploring the metabolism and functionality of fatty acids. We caught up with him to find out more about his career and research…


1. Can you tell us about your career path, and how you got to your current position as Head of Human Development and Health and Professor of Nutritional Immunology within Medicine at University of Southampton? 

I am originally from New Zealand and completed a PhD in Biochemistry at the University of Auckland in 1987. After that, I got a Fellowship to spend time at the University of Oxford. I ended up staying in Oxford for 8 years (1987-1995), 4 years as a Fellow and 4 years as a Lecturer. In 1995 I was offered a Lectureship in Human Nutrition at the University of Southampton. I was promoted to Reader in 1998 and was awarded a Chair in Nutritional Immunology in 2002. I have run my own research group since 1991. I became Head of the School of Human Development and Health within the Faculty of Medicine at University of Southampton in 2018.


2. What led you to your research interest in the metabolism and functionality of fatty acids? 

When I arrived in Oxford in 1987, the lab chief Eric Newsholme suggested to me that studying fatty acid metabolism in immune cells would be worthwhile. He was thinking about energy generation, because at that time most people thought the immune system was fuelled solely by glucose, but some of Eric’s recent PhD students had shown that both lymphocytes and macrophages could generate energy from fatty acid oxidation. I wondered whether immune cells could metabolise different types of fatty acids and began cell culture experiments with macrophages to investigate this. What I found was that the cells behaved differently according to the fatty acids they were exposed to; specifically I looked at two important processes early on in my work: adhesion of macrophages to different surfaces and the ability of macrophages to engulf foreign particles. I demonstrated that omega-3 fatty acids could modulate both of these processes and identified that this probably related to incorporation of the fatty acids into the membranes of macrophages. So began a long journey exploring the functionality of fatty acids particularly in the context of the immune system, trying to understand the effects and the mechanisms involved.


3. Omega-3 fatty acids from fish oils have been shown to have a cardioprotective action, but does it make a difference whether we consume these through oily fish or through supplements? What are your views on the current UK recommendation to eat one portion of oily fish per week? 

Yes, omega-3 fatty acids from fish and from fish oil supplements lower risk of developing cardiovascular disease and have been shown in some studies to be useful in treating people who already have cardiovascular disease. So, they have both protective (or preventive) and therapeutic effects. These effects are described through association studies and through intervention trials. The former are typically about intake from the diet, mainly from fish, while the latter have been mainly done with supplements. Both fish (especially what we call fatty or oily fish, like salmon, sardines and mackerel) and supplements provide the bioactive omega-3s EPA and DHA and so both can be of benefit. However, it is interesting that association studies indicate a stronger link with fish than with EPA and DHA themselves. This may be because fish are a good source of other important nutrients or that fish replace sources of less healthy nutrients. The Government recommendation to eat at least one portion of oily fish per week has a scientific basis and I am supportive of that. But probably people need to eat more than one portion to get the full benefit; this is one reason why I like the wording of the recommendation (“at least”). If you read the Government’s recommendation in full you will see that it includes guideline ranges suggesting intake of several portions per week for some subgroups of the population and conveying a sentiment that people should not be prevented from eating as much oily fish as they wish. Unfortunately, too few people in Britain eat oily fish regularly. There are many reasons for this.          


4. What future research would like to see within the field of metabolism and functionality of fatty acids? 

We know a lot already on this but there are many unanswered questions and new questions come up all the time. One important question is whether EPA and DHA have different roles. Another is whether omega-3 DPA also has effects like EPA and DHA do. One important question is whether different people handle and respond to EPA and DHA differently, and if they do, why that is. Another series of questions I am very interested in is the relative importance of plant and fish derived omega-3 fatty acids and why the metabolic conversion of the plant to the fish forms operates differently in different people. These are important questions when the lack of sustainability of fish is considered: we need alternative sustainable sources of bioactive fatty acids. These may be functional in their own right or may be converted in the body into the bioactive fatty acids.   


5. You have published several scientific research papers (over 500 to be more precise), but are there any research projects that you feel were the most instrumental within the development of your career? 

This is a really hard question I think. I have been involved in dozens of research projects using different experimental systems: cell cultures, laboratory animals, farm animals, pregnant women, children, young adults, older people, and various patient groups. Each of these has generated novel and exciting findings. Some of the work using cell cultures and lab animals lead to discoveries of new effects of fatty acids and of new mechanisms of action. At various times I have been able to apply new technologies to understanding fatty acid functional effects and likely mechanisms (techniques like flow cytometry, PCR, ELISA when they were quite new for example) and that proved to be very important in terms of making discoveries and career development. Many of my human studies have also been really important I think. For example, early studies of fish oil supplementation reporting on effects on inflammation and immune responses, our study of effects of salmon consumption by pregnant women on immunity and allergy in their babies, and our detailed study of the dose- and time-dependent enrichment of different body pools with EPA and DHA have all been really important. I think the single most important study I have been involved in was a clinical trial that showed that omega-3 fatty acids act to make atherosclerotic plaques (the fatty build-up in the blood vessel wall) more stable, probably by reducing inflammation.  This effect could explain why omega-3 can lower mortality from cardiovascular disease.


6. You have been involved with lots of research projects, but could you share with us one of the projects you have been involved with recently and what the findings were? 

Well most of my research has been about fatty acids, mainly the plant and fish derived omega-3s but also other interesting fatty acids like arachidonic acid and conjugated linoleic acid. However, I have also worked with amino acids, antioxidant vitamins and both prebiotics and probiotics. One study with prebiotics showed a small improvement in immune response in middle aged adults, assessed by measuring the response to the seasonal flu vaccine. This study suggests that changing the gut microbiota could improve the individual’s immune defences. I have been involved in a few probiotic studies looking at this. The findings have been a bit inconsistent and I think both the specific organism(s) used and the type of individuals being studied are important factors to consider and to understand much better.


7. As the former president of the Nutrition Society and now the president of the Federation of European Nutrition Societies (FENS) what do you enjoy most about the additional responsibilities these roles involve taking on?   

I was President of the Nutrition Society from 2016 to 2019 and since October 2019 I have been President of the Federation of European Nutrition Societies (FENS), a four year role. I think the most rewarding part of these sorts of roles is being able to help to make changes that improve things for the Society members and also for the broader discipline. In my new role in FENS I have initiated an activity about enhancing trust in the science of nutrition that will look at how nutrition science organises itself and does its research; how it interacts internally, with other biomedical sciences, and with industry; and how it communicates with the medical community, the public and patients. What I am hoping will come out of this is new ways of thinking, behaving and working that will help the discipline of nutrition science to better address the current and future challenges that it faces.  


8. What do you enjoy most about your role at the University of Southampton? Do you have a favourite module to teach and if so, why?  

I am now a leader and a manager (of my research group and of my School) – that means a lot of meetings - but I still love talking about research with my team and presenting and publishing research. I lecture both science students (3rd year) and medical students (1st and 2nd year) on a variety of topics around metabolism and diet, nutrition and health. I have a series of four lectures on Diet, lipoproteins and cardiovascular disease that I really enjoy giving to 3rd year science students. These lectures enable me to very clearly relate the importance of diet to major health outcomes, to show that dietary components can act through very sophisticated molecular and cellular mechanisms, and to introduce the significant controversy that exists in this area. Overall this shows nutrition to be an important, modern, and exciting scientific discipline of relevance to everyone. What could be more rewarding than that?


9. What does a typical working day look like for you? 

I get to work at 7.45 am most days (unless I am away at a conference or suchlike). Usually I have a number of meetings – with staff in my School or management meetings in the School or Faculty – and in between these I am dealing with the constant email traffic, carrying out administrative tasks and, if I am lucky, meeting with some of my research team. I may spend some time preparing a talk or searching the literature for something. I usually leave at about 5.30 pm. I do a lot of work at home in the evenings and that is where I do most of my writing (research papers, reviews, funding applications and so on), journal and peer review work, and preparing lectures and presentations.


10. If you could give one tip to aspiring students what would it be?

Modern research is complex and can be technically challenging and doing research has its ups and downs. So, I think limiting me to just one tip is tough! So I am going to ignore that - I would say that research students who aspire to do well should take advantage of opportunities that arise, should network and collaborate, must get to really know their subject and absolutely need to be resilient.