J Epidemiol Community Health 58:288-289 doi:10.1136/jech.2003.014274
  • Evidence based public health policy and practice

Effect of dietary advice to increase fruit and vegetable consumption on plasma flavonol concentrations: results from a randomised controlled intervention trial

  1. R R Huxley1,
  2. M Lean2,
  3. A Crozier2,
  4. J H John1,
  5. H A W Neil1,
  6. for the Oxford Fruit and Vegetable Study Group
  1. 1Division of Public Health and Primary Care, Institute of Health Sciences, University of Oxford, Headington, Oxford, UK
  2. 2Plant Products and Human Nutrition Laboratory, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK
  1. Correspondence to:
 Dr R Huxley
 Institute for International Health, 144 Burren Street, Newtown, Sydney, NSW 2042, Australia;
  • Accepted 28 August 2003

A recent meta-analysis of prospective cohort studies suggests that high dietary intakes of flavonols are associated with a significantly lower risk of coronary heart disease mortality.1 The major dietary sources of flavonols such as quercetin, kaempferol, and isorhamnetin are tomatoes, onions, kale, broccoli, celery, apples, and cherries, while catechins are concentrated in tea and red wine.2,3 No clinical trials have examined the effect of interventions to increase habitual fruit and vegetable intake on plasma flavonol concentrations in free living populations. As the principal dietary sources of flavonols are restricted to a few specific food types, it is uncertain whether general dietary advice to increase fruit and vegetable consumption will increase plasma flavonol concentrations. We conducted a randomised controlled trial to investigate the effect over six months of an intervention to increase fruit and vegetable intake in a free living population and investigated what impact this intervention had on plasma concentrations of flavonols.4


The methods are outlined in more detail elsewhere.4 In brief, we undertook a randomised six month parallel group controlled trial using a brief negotiation model to encourage increased consumption of fruit and vegetables to at least five portions per …