Elsevier

The Lancet

Volume 359, Issue 9322, 8 June 2002, Pages 1969-1974
The Lancet

Articles
Effects of fruit and vegetable consumption on plasma antioxidant concentrations and blood pressure: a randomised controlled trial

https://doi.org/10.1016/S0140-6736(02)98858-6Get rights and content

Summary

Background

High dietary intakes of fruit and vegetables are associated with reduced risks of cancer and cardiovascular disease. Short-term intensive dietary interventions in selected populations increase fruit and vegetable intake, raise plasma antioxidant concentrations, and lower blood pressure, but long-term effects of interventions in the general population are not certain. We assessed the effect of an intervention to increase fruit and vegetable consumption on plasma concentrations of antioxidant vitamins, daily fruit and vegetable intake, and blood pressure.

Methods

We undertook a 6-month, randomised, controlled trial of a brief negotiation method to encourage an increase in consumption of fruit and vegetables to at least five daily portions. We included 690 healthy participants aged 25–64 years recruited from a primary-care health centre.

Findings

Plasma concentrations of α-carotene, β-carotene, lutein, β-cryptoxanthin, and ascorbic acid increased by more in the intervention group than in controls (significance of between-group differences ranged from p=0·032 to 0·0002). Groups did not differ for changes in lycopene, retinol, α-tocopherol, γ-tocopherol, or total cholesterol concentrations. Self-reported fruit and vegetable intake increased by a mean 1·4 (SD 1·7) portions in the intervention group and by 0·1 (1·3) portion in the control group (between-group difference=1·4, 95% CI 1·2–1·6; p<0·0001). Systolic blood pressure fell more in the intervention group than in controls (difference=4·0 mm Hg, 2·0–6·0: p<0·0001), as did diastolic blood pressure (1·5 mm Hg, 0·2–2·7; p=0·02).

Interpretation

The effects of the intervention on fruit and vegetable consumption, plasma antioxidants, and blood pressure would be expected to reduce cardiovascular disease in the general population.

Published online May 28, 2002. http://image.thelancet.com/extras/01art9006web.pdf

Introduction

Ecological and epidemiological evidence suggest that high consumption of fruit and vegetables is associated with a reduced risk of cancer1 and cardiovascular disease.2 Several mechanisms have been proposed for this process, including an increased nutrient intake of antioxidant compounds. However, intervention trials of vitamin supplements to increase circulating plasma concentrations of antioxidant vitamins have produced little evidence to support this hypothesis.3, 4, 5, 6 The health benefits of eating fruit and vegetables may be due, in part, to mechanisms other than their antioxidant vitamin content such as blood pressure lowering.7 Current evidence, including unpublished trial data (http://www.hpsinfo.org), therefore points to the beneficial effects of eating more fruit and vegetables rather than vitamin supplementation.

An average daily intake of at least five portions of fruit and vegetables is recommended in the UK,8 which would represent an increase in consumption of 50%9 with only about 40% of men and women currently achieving this target.10 Although short-term intensive dietary interventions in highly selected populations increase fruit and vegetable intake substantially,11, 12 raise plasma antioxidant concentrations,12 and lower blood pressure,7 whether such interventions are feasible in the general population is uncertain. We did a randomised, controlled trial to investigate the effect of a 6-month primary-care intervention to increase fruit and vegetable consumption in a healthy general population with a wide range of eating habits.

Section snippets

Participants

We identified all patients aged 25–64 years without serious chronic illness from the lists of two general practices based in a health centre in Thame, Oxfordshire, UK. The general practices had few patients from ethnic minorities. We excluded patients with cardiovascular diseases (other than hypertension), gastrointestinal disease, cancer, serious psychiatric disorders, or hypercholesterolaemia; patients who had undergone a recent traumatic event, such as bereavement; and those unable to give

Participants

1045 (45%) of 2302 eligible mailed patients responded to the initial invitation (figure). Respondents were older than non-respondents (mean [SD] age 46·1 [10·1] years vs 40·1 [10·3] years; difference 6·0 years, 95% CI 5·2–6·9) and a higher proportion were women (55% vs 48%; difference 7%, 2·9–11·1). Respondents were less materially deprived than non-respondents (mean Townsend material deprivation score19 −0·98 (1·35) vs −0·75 (1·38); difference −0·23, −0·34 to −0·12). 316 respondents (207 women

Discussion

Our results show that a primary-care intervention can increase self-reported fruit and vegetable intake; raise plasma concentrations of α-carotene, β-carotene, lycopene, β-cryptoxanthin, and ascorbic acid; and result in significant decreases in systolic and diastolic blood pressure.

Our analysis included all possible randomised patients irrespective of complete data or compliance. The study population was demographically heterogeneous with men and women aged 25–64 years being eligible for

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