Vegetable-enriched bread: Pilot and feasibility study of measurement of changes in skin carotenoid concentrations by reflection spectroscopy as a biomarker of vegetable intake.

Globally, bread is a staple food and thus a promising vehicle for the delivery of nutrients from vegetables including carotenoids. The aim of this pilot/feasibility, pre-post experimental study was to measure skin (Veggie Meter™) and plasma carotenoid concentrations 1 week before (week -1), immediately prior to (week 0), and after (week 2) 14 days of daily consumption of 200 g pumpkin- and sweetcorn-enriched bread (VB). At each measurement point, total vegetable and fruit intake and specific carotenoid-rich foods were assessed by questionnaire. Participants ( n  = 10, 8 males, 2 females) were aged between 19 and 39 years and weighed 90 ± 20 kg. Vegetable and fruit intake was low and less than one serving/day of foods containing carotenoids. Prior to the intervention, measures of carotenoid-containing foods and skin or plasma carotenoids were not different when measured a week apart. Consumption of the VB did not result in statistically significant changes in either the skin or plasma carotenoid measurements. Plasma carotenoid concentrations and the carotenoid reflection scores had a large and positive ( r  = .845, 95% CI 0.697, 0.924) association. The relationship between the number of servings of carotenoid-rich foods with the plasma carotenoid and carotenoid reflection scores was positive and of moderate strength. In conclusion, carotenoid status was not measurably changed with the consumption of 200 g VB each day for 2 weeks. Subjective carotenoid-rich food intake was positively associated with objective biomarkers of carotenoids. The Veggie meter™ has the potential to provide portable measurement of circulating carotenoids and be indicative of intake of carotenoid-rich foods.