A novel combined biomarker including plasma carotenoids, vitamin C, and ferric reducing antioxidant power is more strongly associated with fruit and vegetable intake than the individual components

Common Limitations and Challenges of Dietary Clinical Trials for Translation into Clinical Practices

The progressive development of clinical and public health nutrition has long relied on dietary clinical trials (DCTs), investigating the causal relationship between diet and multiple risk factors of non-communicable and chronic diseases. DCTs are also hallmarks for establishing dietary requirements and promoting overall nutritional health among the population. Despite their critical importance in translation into public health strategies and practices, DCTs have several limitations and challenges for study design, implementation and finding interpretation. The complex nature of nutrition interventions, collinearity between diet components, multi-target effects of the interventions, diverse dietary behaviors, and food culture are the most challenging issues. Furthermore, baseline exposure and dietary status, appropriate control groups, blinding, randomization, and poor adherence undermine the effectiveness of DCTs in translation into practices. Disruptive factors will be minimized if researchers are committed to following good clinical practice (GCP) standards available for common designs of clinical trials. Planning DCTs, however, needs careful considerations for hypothesis generation, study design development, the definition of primary and secondary outcome measures, and target population.

Double Up Food Bucks Participation is Associated with Increased Fruit and Vegetable Consumption and Food Security Among Low-Income Adults

OBJECTIVE

To evaluate the effect of the Utah Double Up Food Bucks (DUFB) program on fruit and vegetable (F&V) intake and food security status among Supplemental Nutrition Assistance Program (SNAP) recipients.

METHODS

Data were collected in 2015, using a before-and-after study design. At the farmers' market, a convenience sample of SNAP recipients was recruited for a survey and a 4-week telephone follow-up survey. Differences between the 2 surveys in food security and F&V intake were tested using the Wilcoxon signed-rank test.

RESULTS

Follow-up surveys were completed with 138 (40%) of the 339 baseline participants. Median F&V consumption increased from 2.82 times per day to 3.29 times per day (median, interquartile range 1.48-3.99 and 3.28-5.02, respectively, P = .002). The percentage of DUFB participants who were food secure increased by 15% (P = .001).

CONCLUSIONS AND IMPLICATIONS

The present results add to the growing literature indicating farmers' market incentives are associated with increased F&V consumption and decreased food insecurity. Although more research is needed, farmers' market incentives may be an effective area of policy intervention.

Identification of Urinary Polyphenol Metabolite Patterns Associated with Polyphenol-Rich Food Intake in Adults from Four European Countries

We identified urinary polyphenol metabolite patterns by a novel algorithm that combines dimension reduction and variable selection methods to explain polyphenol-rich food intake, and compared their respective performance with that of single biomarkers in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. The study included 475 adults from four European countries (Germany, France, Italy, and Greece). Dietary intakes were assessed with 24-h dietary recalls (24-HDR) and dietary questionnaires (DQ). Thirty-four polyphenols were measured by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS-MS) in 24-h urine. Reduced rank regression-based variable importance in projection (RRR-VIP) and least absolute shrinkage and selection operator (LASSO) methods were used to select polyphenol metabolites. Reduced rank regression (RRR) was then used to identify patterns in these metabolites, maximizing the explained variability in intake of pre-selected polyphenol-rich foods. The performance of RRR models was evaluated using internal cross-validation to control for over-optimistic findings from over-fitting. High performance was observed for explaining recent intake (24-HDR) of red wine (r = 0.65; AUC = 89.1%), coffee (r = 0.51; AUC = 89.1%), and olives (r = 0.35; AUC = 82.2%). These metabolite patterns performed better or equally well compared to single polyphenol biomarkers. Neither metabolite patterns nor single biomarkers performed well in explaining habitual intake (as reported in the DQ) of polyphenol-rich foods. This proposed strategy of biomarker pattern identification has the potential of expanding the currently still limited list of available dietary intake biomarkers.

Use of biomarkers to assess fruit and vegetable intake

A high intake of fruit and vegetables (FV) has been associated with reduced risk of a number of chronic diseases, including CVD. The aim of this review is to describe the potential use of biomarkers to assess FV intake. Traditional methods of assessing FV intake have limitations, and this is likely to impact on observed associations with disease outcomes and markers of disease risk. Nutritional biomarkers may offer a more objective and reliable method of assessing dietary FV intake. Some single blood biomarkers, such as plasma vitamin C and serum carotenoids, are well established as indicators of FV intake. Combining potential biomarkers of intake may more accurately predict overall FV intake within intervention studies than the use of any single biomarker. Another promising approach is metabolomic analysis of biological fluids using untargeted approaches to identify potential new biomarkers of FV intake. Using biomarkers to measure FV intake may improve the accuracy of dietary assessment.

Associations between reported intakes of carotenoid-rich foods and concentrations of carotenoids in plasma: a validation study of a web-based food recall for children and adolescents

Objective

To validate estimated intakes of carotenoid-rich foods from a web-based food recall (WebFR) using carotenoids in blood as an objective reference method.

Design

Cross-sectional validation study using carotenoids in plasma to evaluate estimated intakes of selected carotenoid-rich foods. Participants recorded their food intake in the WebFR and plasma concentrations of β-carotene, α-carotene, β-cryptoxanthin, lycopene, lutein and zeaxanthin were measured.

Setting

Schools and homes of families in a suburb of the capital of Norway.

Subjects

A total of 261 participants in the age groups 8–9 and 12–14 years.

Results

Spearman’s rank correlation coefficients ranged from 0·30 to 0·44, and cross-classification showed that 71·6–76·6 % of the participants were correctly classified, when comparing the reported intakes of carotenoid-rich foods and concentrations of the corresponding carotenoids in plasma, not including lutein and zeaxanthin.

Conclusions

Correlations were acceptable and cross-classification analyses demonstrated that the WebFR was able to rank participants according to their reported intake of foods rich in α-carotene, β-carotene, β-cryptoxanthin and lycopene. The WebFR is a promising tool for dietary assessment among children and adolescents.