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Table 2 Correlation coefficientsa and 95% confidence intervals of skin carotenoids, plasma carotenoids, and self-reported vegetable and fruit intake at baseline and across one year

From: Concurrent validity of skin carotenoid status as a concentration biomarker of vegetable and fruit intake compared to multiple 24-h recalls and plasma carotenoid concentrations across one year: a cohort study

  Total plasma carotenoids (μM/L)d VF (cup eq.)b Dietary carotenoids (mg/d)b
  Baseline Year Baseline Year Baseline Year
Reflection spectroscopyc 0.70***
(0.53, 0.82)
0.65***
(0.46, 0.79)
0.27
(0.00, 0.51)
0.37**
(0.10, 0.58)
0.10
(−0.18, 0.36)
0.24
(− 0.03, 0.48)
Resonance Raman spectroscopyc 0.77***
(0.63, 0.86)
0.69***
(0.52, 0.81)
0.33*
(0.06, 0.55)
0.37**
(0.11, 0.59)
0.27
(0.00, 0.51)
0.29*
(0.02, 0.52)
Total plasma carotenoids (μM/L)d    0.27
(0.00, 0.51)
0.36**
(0.10, 0.58)
0.24
(−0.03, 0.48)
0.33*
(0.06, 0.55)
VF (cup eq.)b      0.56***
(0.34, 0.72)
0.51***
(0.27, 0.69)
  1. aPairwise correlations at baseline were estimated using Pearson coefficients and full-year between-individual correlations were estimated using a mixed model
  2. bMeasured by the Automated Self-Administered 24-Hour (ASA24) Dietary Assessment Tool at 36 times over the year
  3. cMeasured at 12 times over the year
  4. dMeasured at 4 times over the year
  5. Analyzed carotenoids were α- and β-carotene, β-cryptoxanthin, lycopene, lutein and zeaxanthin
  6. *Significant at P < 0.05
  7. **Significant at P < 0.01
  8. ***Significant at P < 0.001