Resonance Raman measurements of carotenoids using light-emitting diodes

Stakeholder selected strategies for obesity prevention in childcare: results from a small-scale cluster randomized hybrid type III trial

BACKGROUND

Together, We Inspire Smart Eating (WISE) is an intervention for the early care and education setting to support children's exposure to and intake of fruits and vegetables. WISE emphasizes 4 evidence-based practices (EBPs): (1) use of a mascot; (2) educators' role modeling; (3) positive feeding practices; and (4) hands-on exposures. The current study reports on a small-scale implementation trial aimed at improving the use of WISE EBPs by teachers.

METHODS

A Hybrid Type III Cluster Randomized Design compared a Basic and Enhanced implementation strategy. The Basic Strategy included training and reminders only; the Enhanced strategy was a multi-faceted package of stakeholder-selected strategies including a leadership commitment, an implementation blueprint, a local champion, an environmental reminder of the EBPs, facilitation, and tailored educational resources and incentives. All study sites were Head Starts. Sites were randomized using a balancing technique that considered site characteristics; 4 sites (20 classrooms, 39 educators, 305 children) received Enhanced support; 5 sites (18 classrooms, 36 educators, 316 children) received Basic support. RE-AIM guided the evaluation, and implementation fidelity was the primary outcome. Strategies were assessed using examination of data distributions and unadjusted comparisons (t tests) as well as general linear and mixed effects models controlling for covariates.

RESULTS

For the primary outcome of fidelity, the Enhanced group had significantly higher means for 3 of 4 EBPs. Multivariate models explained a significant portion of variance for both mascot use and hands-on exposure with a significant positive effect observed for treatment condition. The Enhanced group also had higher rates of Appropriateness and Organizational Readiness for Implementing Change (as indicators of implementation and adoption, respectively). There was no significant difference between groups for indicators of Reach, Effectiveness or Maintenance. Formative interviews indicated key targets for iteration and potential mechanisms. Key events were catalogued to provide context for interpretation (e.g., 61% of classrooms with turnover).

CONCLUSIONS

Findings were mixed but suggested promise for the Enhanced strategy, especially considering key events of the study. Implementation fidelity improvements occurred mainly in the last 3 months of the school year; additional time may be needed to translate to improvements in child outcomes.

TRIAL REGISTRATION

NCT03075085 Registered 20 February 2017.

Skin carotenoids: a biomarker of fruit and vegetable intake in children

BACKGROUND

Studies of adult subjects have found a strong correlation between serum carotenoids and skin carotenoids measured by resonance Raman spectroscopy (RRS). No published studies have examined correlations between skin and serum carotenoids among children.

OBJECTIVES

We aimed to validate skin RRS methodology against serum carotenoid measurements by high-performance liquid chromatography and to determine whether RRS can be used as a valid biomarker of fruit and vegetable (F/V) intake among children.

DESIGN

In our cross-sectional study, participants were 45 healthy children aged 5 to 17 years who provided three blood samples used to assess serum carotenoid concentrations and three RRS skin measurements of the palm within a 4-week period. Dietary intake of F/V was assessed three times within 4 weeks using a 27-item food frequency questionnaire (FFQ) and an automated multiple-pass 24-hour daily recall. Estimates of intake from three FFQs, completed at least 7 days apart, were averaged. Estimates of intake from 24-hour daily recalls were collected on 2 weekdays and 1 weekend day and averaged.

RESULTS

Levels of skin and serum carotenoids were highly correlated (R(2)=0.62; P<0.001). A linear regression model, controlling for child's weight and scanner unit, predicted that for every unit increase of total F/V from FFQ and total F/V as assessed by 24-hour daily recall, RRS intensity was predicted to increase by 3,798 (P=0.001) and 3,504 (P=0.001), respectively. Similar results were observed for reported high-carotenoid vegetable intake. Total carotenoid and beta carotene levels from 24-hour daily recalls correlated to total serum carotenoids levels (P<0.01 and P<0.05, respectively). Total carotenoid, alpha carotene, and beta carotene levels from the 24-hour daily recalls correlated to RRS (P<0.01).

CONCLUSIONS

Skin carotenoids measured by RRS were strongly correlated with serum carotenoid levels and were positively associated with estimates of intake from FFQ and an automated multiple-pass 24-hour daily recall among children aged 5 to 17 years. Skin carotenoids may be used as valid biomarker of F/V intake among children.

Resonance Raman spectroscopic evaluation of skin carotenoids as a biomarker of carotenoid status for human studies

Resonance Raman spectroscopy (RRS) is a non-invasive method that has been developed to assess carotenoid status in human tissues including human skin in vivo. Skin carotenoid status has been suggested as a promising biomarker for human studies. This manuscript describes research done relevant to the development of this biomarker, including its reproducibility, validity, feasibility for use in field settings, and factors that affect the biomarker such as diet, smoking, and adiposity. Recent studies have evaluated the response of the biomarker to controlled carotenoid interventions, both supplement-based and dietary [e.g., provision of a high-carotenoid fruit and vegetable (F/V)-enriched diet], demonstrating consistent response to intervention. The totality of evidence supports the use of skin carotenoid status as an objective biomarker of F/V intake, although in the cross-sectional setting, diet explains only some of the variation in this biomarker. However, this limitation is also a strength in that skin carotenoids may effectively serve as an integrated biomarker of health, with higher status reflecting greater F/V intake, lack of smoking, and lack of adiposity. Thus, this biomarker holds promise as both a health biomarker and an objective indicator of F/V intake, supporting its further development and utilization for medical and public health purposes.

Comparison of two methods for noninvasive determination of carotenoids in human and animal skin: Raman spectroscopy versus reflection spectroscopy

Based on compelling in vivo and in vitro studies on human skin, carotenoids are thought to be of great interest as powerful antioxidants acting to prevent free-radical-induced damages, including premature skin ageing and the development of skin diseases such as cancer. Among the available techniques that are suitable for noninvasive determination of carotenoids in human skin, are resonance Raman spectroscopy (RRS) and reflection spectroscopy (RS). For RS, a LED-based miniaturized spectroscopic system (MSS) was developed for noninvasive measurement of carotenoids in human skin. The optimization and subsequent calibration of the MSS was performed with the use of RRS. A strong correlation between the carotenoid concentration determined by the RS and for the RRS system was achieved for human skin in vivo (R = 0.88) and for bovine udder skin in vitro (R = 0.81).

Dermal carotenoid measurements via pressure mediated reflection spectroscopy

We describe a reflection-based method for the quantitative detection of carotenoid antioxidants in living human skin. The skin tissue site of interest is illuminated with broad-band white light spanning the spectral range from 350-850 nm and the spectral composition of the diffusively reflected light is analyzed in real time. Topical pressure is applied to temporarily squeeze blood out of the illuminated tissue volume. In this way the influence of oxy-hemoglobin on the reflection spectra is effectively reduced. After a short optical clearing time the carotenoid absorption becomes easily discernable in a 460-500 nm spectral window and its optical density can be calculated with high accuracy. Our empirical methodology provides a non-invasive rapid determination of skin carotenoid levels, can be used to monitor skin carotenoid concentration changes over time in response to carotenoid containing natural or supplemental diets, and is easily adaptable for applications in clinical and field settings.

Validation model for Raman based skin carotenoid detection

Raman spectroscopy holds promise as a rapid objective non-invasive optical method for the detection of carotenoid compounds in human tissue in vivo. Carotenoids are of interest due to their functions as antioxidants and/or optical absorbers of phototoxic light at deep blue and near UV wavelengths. In the macular region of the human retina, carotenoids may prevent or delay the onset of age-related tissue degeneration. In human skin, they may help prevent premature skin aging, and are possibly involved in the prevention of certain skin cancers. Furthermore, since carotenoids exist in high concentrations in a wide variety of fruits and vegetables, and are routinely taken up by the human body through the diet, skin carotenoid levels may serve as an objective biomarker for fruit and vegetable intake. Before the Raman method can be accepted as a widespread optical alternative for carotenoid measurements, direct validation studies are needed to compare it with the gold standard of high performance liquid chromatography. This is because the tissue Raman response is in general accompanied by a host of other optical processes which have to be taken into account. In skin, the most prominent is strongly diffusive, non-Raman scattering, leading to relatively shallow light penetration of the blue/green excitation light required for resonant Raman detection of carotenoids. Also, sizable light attenuation exists due to the combined absorption from collagen, porphyrin, hemoglobin, and melanin chromophores, and additional fluorescence is generated by collagen and porphyrins. In this study, we investigate for the first time the direct correlation of in vivo skin tissue carotenoid Raman measurements with subsequent chromatography derived carotenoid concentrations. As tissue site we use heel skin, in which the stratum corneum layer thickness exceeds the light penetration depth, which is free of optically confounding chromophores, which can be easily optically accessed for in vivo RRS measurement, and which can be easily removed for subsequent biochemical measurements. Excellent correlation (coefficient R=0.95) is obtained for this tissue site which could serve as a model site for scaled up future validation studies of large populations. The obtained results provide proof that resonance Raman spectroscopy is a valid non-invasive objective methodology for the quantitative assessment of carotenoid antioxidants in human skin in vivo.