Professor Sir Jim Mann.
Professor Jim Mann and his research team conduct research on the role of diet in health outcomes. The team includes Dr Andrew Reynolds (Department of Medicine, The University of Otago) and Dr Lisa Te Morenga (Associate Professor, Research Centre for Hauora and Health at Massey University).
Summary of the impact
A key component of the team's research relates to the benefits and risks of consuming dietary fibre and sugar. Reviews of this and related research by members of the group commissioned by the World Health Organization (WHO), have underpinned WHO nutrition guidelines aimed at reducing the risk of non-communicable diseases.
Professor Mann's impact has been achieved through rigorously building a portfolio of high-quality evidence, including mechanistic studies, randomised controlled trials, observational studies, and meta-analyses. Getting research into guidelines for health professionals has enabled wide dissemination and uptake of his research.
Professor Mann is also highly respected for his extensive working relationships with students and clinicians, and through his willingness and ability to update them with the latest research, including his own, the research is effectively used in practice.
Research
Professor Mann and his colleagues have shown that dietary fibre is protective against the development of serious diseases such as heart disease, type 2 diabetes, and colorectal cancer as well as premature mortality, in Aotearoa New Zealand. The research has shown that increasing dietary fibre improves key clinical risk factors: LDL cholesterol, body weight, and measures of glycaemic control. This work has considered both dietary fibre, a macronutrient, and the food sources of fibre, such as whole grains. A recently-published paper in The Lancet (A. Reynolds et al., 2019), provided high quality evidence that dietary fibre intake should be increased to at least 25g per day, and refined grains replaced with whole grains. The results showed, for the first time, a clear dose-response relationship between dietary fibre and several important health outcomes (the more fibre consumed, the greater the benefit), and have enabled a quantified recommendation for dietary fibre intake.
Work on added sugar by Professor Mann and colleagues has been pivotal in showing the detrimental effects of high intakes on body weight and several risk factors for heart disease. Professor Mann's first research paper in this area was published in The Lancet in 1970 (Mann et al., 1970) and related to the effects of sugar on body weight and lipid-related risk factors for heart disease. In the 1980s he moved from Oxford to New Zealand, where his work has been supported through funding from Health Research Council Programme Grants, the Heart Foundation, Lotteries Health and the Ministry of Business Industry and Enterprise, Healthier Lives National Sciences Challenge. He has significant ongoing international collaboration with the World Health Organization and universities in the United Kingdom and Europe as well as New Zealand.
This work on dietary fibre was commissioned by the World Health Organization and will inform its upcoming recommendations for dietary fibre and carbohydrate intakes. Though recent, this study has achieved excellent exposure, having 300 academic citations, an Altmetric score of over 3,500, and been picked up by 222 news outlets, including Time magazine.
Another recent systematic review study (A. Reynolds et al., 2020) has endorsed the importance of dietary fibre in the management of diabetes in addition to reducing the risk of developing type 2 diabetes, and also for the first time clearly demonstrated its potential to reduce the risk of early mortality in those who already have the disease.
The systematic review of the impact of sugar, led by Dr Lisa Te Morenga (Te Morenga et al., 2013), was commissioned by the World Health Organization (WHO) to provide evidence for their guidelines on sugar. Professor Mann has been a member of the WHO dietary guidelines group since its inception. In 2015, they recommended decreasing added sugars to less than 10 per cent of total energy intake, and noted that further health benefits are observed when free sugars are reduced to less than 5 per cent of total energy intake (WHO | The Science behind the Sweetness in Our Diets, 2014). Professor Mann is still an active member of this WHO group.
Details of the impact
International
Research by Professor Mann and colleagues has been central to dietary guidelines for the management of people with established diabetes. He has led the pan-European group which produced all European dietary guidelines for the prevention and management of diabetes since the 1980s (Mann et al., 2004)). The European guidelines have influenced practice in other countries including New Zealand.
National
In New Zealand, Professor Mann has chaired expert advisory groups to the Ministry of Health on cardiovascular disease and diabetes, nutrition advisory groups for the Ministry of Health, technical advisory groups for the national nutrition surveys, the Heart Foundation Scientific Committee and other groups and committees related to his nutrition research. For example, he chaired the group which produced Eating and Activity guidelines for New Zealand Adults (Ministry of Health, 2015). Professor Mann is the director of the Healthier Lives National Science Challenge, and a co-director of the Edgar Diabetes and Obesity Research Centre, where he was part of a “Fibre Study Day”, which brought researchers and clinicians together.
Professor Mann was knighted in the 2022 New Year's Honours for services to health.
Clinical
Clinical dieticians at Southern District Health Board, Olivia Marchand and Jo Iremonger, are clinical colleagues of Professor Mann's, and greatly value his research and his relationship with their team. Both dieticians have used Professor Mann's research findings, including the fibre and sugar guidelines that have enabled them to influence the food services menu at the hospital. They say it is not only Professor Mann's knowledge and quality of research that makes it easy for others to learn about his research, but his personal qualities of being approachable and willing to share information. Professor Mann has the skill of interpreting research to patients in lay-person language, and his knowledge of the body of research is comprehensive.
“Having Professor Mann's overview and perspective of different research studies has been helpful to us to be able to give a balanced opinion to patients,” says Clinicial Dietician Jo Iremonger.
Pedagogical
Olivia Marchand and Jo Iremonger were also both students of Professor Mann. His lectures, textbooks and research work have had a lasting impression on them. He has supervised over 50 PhD students during his tenure at the University of Otago.
Key points
- Professor Mann's impact has been achieved through rigorously building a portfolio of high-quality evidence
- Getting research into guidelines for health professionals has enabled wide dissemination and uptake of his research.
- Professor Mann has working relationships with students and clinicians, which enables him to update them with the latest research, including his own.
References
- Mann, J. I., De Leeuw, I., Hermansen, K., Karamanos, B., Karlström, B., Katsilambros, N., Riccardi, G., Rivellese, A. A., Rizkalla, S., Slama, G., Toeller, M., Uusitupa, M., Vessby, B., & Diabetes and Nutrition Study Group (DNSG) of the European Association. (2004). Evidence-based nutritional approaches to the treatment and prevention of diabetes mellitus. Nutrition, Metabolism, and Cardiovascular Diseases: NMCD, 14(6), 373–394.
- Mann, J. I., Truswell, A. S., Hendricks, D. A., & Manning, E. (1970). Effects on serum-lipids in normal men of reducing dietary sucrose or starch for five months. The Lancet, 295(7652), 870–872.
- Ministry of Health. (2015). Eating and activity guidelines for New Zealand adults.
- Reynolds, A., Akerman, A. P., & Mann, J. (2020). Dietary fibre and whole grains in diabetes management: Systematic review and meta-analyses. PLOS Medicine, 17(3), e1003053.
- Reynolds, A., Mann, J., Cummings, J., Winter, N., Mete, E., & Morenga, L. T. (2019). Carbohydrate quality and human health: A series of systematic reviews and meta-analyses. The Lancet, 393(10170), 434–445.
- Te Morenga, L., Mallard, S., & Mann, J. (2013). Dietary sugars and body weight: Systematic review and meta-analyses of randomised controlled trials and cohort studies. Bmj, 346, e7492.
- WHO | The science behind the sweetness in our diets. (2014). WHO; World Health Organization.
- World Health Organisation,. (2015). Guideline: Sugars intake for adults and children.