The Role of Genetic Variation in Modulating the Effects of Blended Fruits and Vegetables Versus Fruit- and Vegetable-Coated Food Products on Antioxidant Capacity, DNA Protection, and Vascular Health: A Randomized Controlled Trial

Abstract

Background/Objectives: Fruits and vegetables (F&Vs) are major dietary sources of phytochemicals, crucial for preventing non-communicable diseases. However, barriers such as preparation inconvenience and a short shelf life hinder their consumption. F&V-coated foods have emerged as an alternative. This human nutrition intervention study assessed the effects of a blended F&Vs mixture versus an F&V-coated food on phytochemical absorption and chronic disease risk markers. It also explored how genetic variation influences physiological responses to these F&V products. Methods: In this randomized-controlled trial, participants were assigned to one of three dietary interventions: a blended F&V mixture ("F&V Blend"), a rice-based cereal product coated with this blend ("Coated Pearl"), or the same product without the F&V mixture ("Uncoated Pearl"). The four-week study included a two-week run-in and a two-week intervention phase, each followed by a test day. Measurements included DNA damage resistance (comet assay), plasma antioxidant status (Trolox capacity and superoxide levels), microvasculature health (retinal analysis), and plasma phytochemical concentrations (colorimetric analyses or HPLC). To assess group differences, a linear mixed model was used. Fifteen polymorphic genes related to phytochemical metabolism and oxidative stress were tested using TaqMan and PCR, with outcomes analyzed via ANOVA. Results: The F&V Blend and Coated Pearl products increased plasma carotenoid levels versus the Uncoated Pearl product. Only the F&V Blend improved retinal dilation and DNA resistance. Surprisingly, the Uncoated Pearl product enhanced antioxidant capacity, lowered superoxide levels, and improved retinal microvasculature. Genotype effects were minimal, except for HNF1A, where wildtypes in the Uncoated Pearl group showed a higher antioxidant capacity. Conclusions: Fresh F&Vs were more effective than coated alternatives in improving vascular health and DNA protection.

Keywords: antioxidant activity; chronic disease prevention; fruit and vegetable mixtures; genetic variability; human intervention study; phytochemical enriched foods.

Figure 1

Dietary investigation timeline. A randomized-controlled trial assessing the effects of three dietary interventions: a blended fruits and vegetables mixture (F&V Blend), a rice-based cereal product coated with the F&V Blend (Coated Pearl), and an uncoated version of the rice-based product (Uncoated Pearl). The study consisted of a two-week run-in phase where participants consumed 50 g of F&Vs daily, followed by a two-week intervention phase where participants continued their baseline diet and were randomized to consume 400 g of the F&V Blend, 133 g of the Coated Pearl, or 100 g of the Uncoated Pearl daily. Participants’ compliance was monitored through digital food diaries, weekly check-ins, and periodic collection of study materials. Blood, urine, retinal images, and anthropometric measurements were taken at baseline and post-intervention to assess health outcomes.

Figure 2

(A) Uncoated Pearls; (B) Pearls coated with complex F&V Blend; (C) close-up view of Coated Pearls; (D) F&V Blend (100 g). The F&V Blend was created by blending apples (100 g), green tea (0.5 g in 25 mL water), blueberries (25 g), blue grape (25 g), blackberries (25 g), raspberries (25 g), tomato (33 g), carrots (33 g), red bell pepper (33 g), broccoli (33 g), cauliflower (33 g), Brussels sprouts (33 g) (a total of 400 g), followed by bottling and Pascalization using high-pressure, low-heat technology. The Uncoated Pearls were dry, cereal-like spheres composed of 95% rice flour and 5% oat flour. The Coated Pearls were identical in composition to the Uncoated Pearls but coated with 400 g of the Pascalized F&V Blend. Preparation described in detail in DeBenedictis et al. (2023) [25].

Figure 3

Phytochemical content in Coated and Uncoated Pearls. Data is presented as means ± SEM. Detailed descriptions of measurements of phytochemicals are provided in DeBenedictis et al. (2023) [25].

Figure 4

Comparison of phytochemical concentrations in the F&V Blend versus Coated Pearls. Data is presented as means ± SEM. Detailed descriptions of measurements of phytochemicals are provided in DeBenedictis et al. (2023) [25].

Figure 5

Inclusion flow chart. A total of 89 participants were enrolled in the study. After 2 dropouts, 87 participants were randomly assigned to one of three intervention groups: “F&V Blend” (n = 42), “Infused Pearl” (n = 22), and “Non-infused Pearl” (n = 23). Following a 2-week run-in period, participants underwent baseline testing. During the 2-week intervention, additional dropouts occurred: 1 from the “F&V Blend” group, 2 from the “Infused Pearl” group, and 1 from the “Non-infused Pearl” group. Final post-test data were collected from 41, 20, and 21 participants in each respective group.

Figure 6

Carotenoid levels at baseline and after each intervention. Data is presented as means ± SEM. *** = p < 0.001; significant after FDR correction; * = p < 0.05, significant with LSD correction.

Figure 7

DNA damage (% Tail DNA and Tail Moment) after each DI compared to baseline. Data is presented as means ± SEM. (* = p < 0.05; gray asterisks indicate comparisons that remain statistically significant following LSD correction).

Figure 8

TEAC after each DI compared to baseline. Data is presented as means ± SEM. (TEAC = Trolox equivalent antioxidant capacity. ** = p < 0.005; statistically significant after FDR correction.

Figure 9

Retinal vessel caliber changes at baseline and after each intervention. Data is presented as mean ± SEM. (* = p < 0.05; *** = p < 0.001; significance following FDR correction).

Figure 10

Effect of HNF1A genotype on changes in TEAC after consumption of the Uncoated Pearl compared to baseline. Data is presented as mean + SEM. (TEAC = Trolox equivalent antioxidant capacity; * = p < 0.05 after FDR correction).