Biomarkers of Fruit and Vegetable Intake in Human Intervention Studies: A Systematic Review

Abstract

Observational evidence consistently shows that consumption of a diet rich in fruit and vegetables may offer protection against diseases such as cardiovascular disease and cancer. Assessment of dietary intake is complex and prone to many sources of error. More objective biomarkers of fruit and vegetable intake are therefore of interest. The aim of this review is to examine the usefulness of the main biomarkers of fruit and vegetable intake to act as objective indicators of compliance in dietary intervention studies. A comprehensive search of the literature was conducted using six databases. Suitable papers were selected and relevant data extracted. The papers were categorized into 3 sub-groups: whole diet interventions; mixed fruit and vegetable interventions; and studies involving individual varieties of fruits or vegetables. Ninety-six studies were included in the review. Overall, the most commonly measured, and most consistently responsive, biomarkers were the carotenoids and vitamin C. Based on the results of this systematic review, it remains prudent to measure a panel of biomarkers in fruit and vegetable intervention studies. The only possible exception to this is “fruit only” intervention studies where assessment of vitamin C alone may suffice.

Keywords:

• carotenoids
• flavonoids
• urinary potassium
• vitamin C
• glucosinolates
• dietary intake

Notes

95 papers were included in this review (study selection summarized in Fig. 1 next page). However, one paper reported data for three different studies: one was excluded as it was a single dose acute study; one study is included in the “individual fruit and vegetable studies” section; and one study is included in the “mixed fruit and vegetable studies” section. Hence data for a total of 96 studies is reported in the review.