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Interview: Bearing fruit
28 April 2009
Alan Crozier on flavonoids, David Bellamy and good wine. Carl Saxton investigates
Alan Crozier is professor of plant biochemistry and human nutrition at the University of Glasgow, UK. His research encompasses the absorption, metabolism and protective effects of dietary phenolics and flavonoids in fruits, vegetables and beverages.
What inspired you to become a scientist?
What motivated you to work in the field of biochemistry?
Once again there was no strategic plan. My research in biochemical aspects of human nutrition arose from a chance meeting in 1995 with the Rank Professor of Human Nutrition at the University of Glasgow, the appropriately named Mike Lean, who asked me if I could analyse flavonols. I said yes, little realising the exciting journey that would unfold for both of us.
What projects are you working on at the moment?
We are studying the fate of flavonoids and phenolic compounds in the body following the ingestion of fruit juices, green tea, rooibos tea, coffee and raspberries. And on a totally unrelated side line, I am investigating, with my colleague Professor Douglas Neil, the factors affecting the freshness of langoustines caught off the west coast of Scotland.
What are the current challenges faced in your research?
Assessing the efficacy of individual fruits and beverages in terms of their beneficial effects on human health is a current challenge. We need to identify the compounds involved and determine the bioactivity of their metabolites in vivo and how this impacts on the incidence of non-communicable diseases such as cardiovascular diseases, diabetes mellitus and cancer.
If you had to choose one of your papers as the one that gives you the most pride, which would that be?
A 1980 paper hidden away in the Encyclopaedia of Plant Physiology entitled Quantitative analysis of plant hormones,1 which is little known and rarely quoted. This paper was the brain-child of my extremely talented co-author David Reeve and it took more than 18 months to evolve. It looks at the data produced by different analytical techniques, in particular HPLC, GC and mass spectrometry, during the analysis of trace levels of endogenous plant hormones, and discusses how accuracy can be objectively assessed in terms of either selectivity or the amount of information generated. It is as relevant today as it was in 1980, perhaps even more so, and the concepts developed have served me well throughout my career. It is interesting to reflect how many investigators and reviewers, not just in the field of nutrition, mistakenly believe that reproducible analytical data reflects accuracy when it does nothing of the sort as it is merely a reflection of precision.
One of your areas of interest involves secondary metabolites in plants. What are these?
Plant secondary metabolites are a diverse and large group of organic compounds that in planta do not appear to have a direct role in photosynthesis, respiration or growth and development. They can accumulate in surprisingly high concentrations and are often distributed among limited taxonomic groups in the plant kingdom. Caffeine is a typical example, being produced in substantial quantities by a very limited number of plant species. The function of many secondary metabolites is not known but it has recently been established using transgenic caffeine-producing tobacco plants that caffeine acts as a natural pesticide.2 Flavonols, which are of significance in the human diet, are concentrated in leaf epidermal cells where they act as UV protectants.3
What is your favourite plant, and why?
What's hot at the moment in the field of human nutrition?
The work of Jim Joseph at Tuft's University in Boston showing that consumption of blueberry and strawberry extracts improves cognitive function of elderly rats.4 When coupled with the results of the Kame study, which suggests that long-term, moderate consumption of fruit and vegetable juices by elderly humans can reduce the incidence of Alzheimer's disease,5 the door is open to some exciting possibilities linking diet to an improved quality of life as well as longevity.
Eating five portions of fruit and vegetables per day is said to be beneficial to one's health. From your research are there any fruits or vegetables that are better than others?
Although it is far from proven, I suspect that in terms of efficacy and potential protective effects, those near the top of the league table will include flavonol-rich onions, cocoa products with a high flavan-3-ol monomer and procyanidin content, green tea which is an extremely rich source of flavan-3-ol monomers, pomegranates because they contain unusually high levels of ellagitannins, coffee because of the high levels of chlorogenic acids and last, but not least, a full bodied red wine produced from Tannat grapes which will contain high concentrations of many flavonoids and phenolic compounds.
What do you love about your job?
What do you do in your spare time?
Football, supporting Sunderland, hopefully in the Premiership, and, too infrequently, playing golf (badly) and hill walking.
If you weren't a scientist, what would you be?
In my dreams, originally a footballer but now a successful professional golfer!
1. D R Reeve and A Crozier, in Hormonal Regulation of Development 1. Molecular Aspects of Plant Hormones, Encyclopedia of Plant Physiology New Series, ed. J MacMillan, Springer-Verlag, Heidelberg, 1980, vol. 9, pp. 203-280.
2. Y-S Kim and H Sano, Phytochemistry, 2008, 69, 882.
3. J Li, T M Ou-Lee, R Raba, R G Amundson and R L Last, Plant Cell, 1993, 5, 171. R Lois, Planta, 1994, 498.
4. B Shukitt-Hale, A N Carey, D Jenkins, B M Rabin and J A Joseph, Neurobiol. and Ageing, 2007, 1187.
5. Q Dai, A R Borenstein, Y Wu, J C Jackson and E B Larson, Am. J. Med., 2006, 119, 751.
Alan Crozier's homepage
Research and recent publications of Alan Crozier
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