Size doesn't matter, brightness does

Brightly coloured fruits and vegetables apparently reduce the risk of developing inflammatory polyarthritis, including rheumatoid arthritis.

The latest "eat your fruits and vegetables" advice comes from a UK study, in which researchers found that eating brightly coloured fruits and vegetables - oranges and bell peppers, for example - reduces the risk of developing inflammatory polyarthritis.

It is not the colour that matters, but the content of the pigment beta-cryptoxanthin, said Dorothy Pattison, PhD, a research dietician at the University of Manchester. Dietary beta-cryptoxanthin is an anti-oxidant, thought to protect against inflammation.

The results of a prospective population-based study of more than 25,000 participants showed that people who developed inflammatory disorders had consumed significantly less of beta-cryptoxanthin than had controls, Pattison and colleagues reported in the August issue of the American Journal of Clinical Nutrition.

A single glass of freshly-squeezed orange juice a day is enough to eliminate the excess risk.

Researchers analysed health questionnaires and diet diaries completed by participants in the European Prospective Investigation of Cancer-Norfolk study of diet and chronic disease in the 1990s.

Participants were followed to identify new cases of inflammatory polyarthritis, including rheumatoid arthritis, and their diets were compared to those of age- and sex-matched controls.

Among the 88 people who developed inflammatory polyarthritis, median dietary intakes of beta-cryptoxanthin and another carotenoid, zeaxanthin, were 40 per cent and 20 per cent lower, respectively, than in the 176 controls. Both differences were statistically significant at the p=0.02 and p=0.05 statistical levels, respectively.

Intake levels were dividied into tertiles. Those who had developed inflammatory polyarthritis were less likely to be in the top tertile of beta-cryptoxanthin and zeaxanthin intake - greater than 365 and 39 micrograms, respectively - although the association was not statistically significant.

However, when the analysis was adjusted to account for smoking, total protein intake and total energy intake, the association with beta-cryptoxanthin became significant. The odds ratio was 0.42, with a 95 per cent confidence interval of 0.2 to 0.88.

"Diets high in beta-cryptoxanthin, and probably zeaxanthin, are associated with a reduced risk of developing inflammatory polyarthritis," Dr Pattison concluded.