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Is plasma vitamin C an appropriate biomarker of vitamin C intake? A systematic review and meta-analysis.

Dehghan M, Akhtar-Danesh N, McMillan CR, Thabane L - Nutr J (2007)

Bottom Line: A total of 26 studies were selected and their results were combined using meta-analytic techniques with random-effect model approach.An overall correlation of 0.39 was found when using the weight record method.Adjusting for energy intake improved the observed correlation for FFQ from 0.31 to 0.41.

View Article: PubMed Central - HTML - PubMed

Affiliation: Population Health Research Institute, School of Medicine, McMaster University, Hamilton, Canada. mahshid@ccc.mcmaster.ca

ABSTRACT

Background: As the primary source of dietary vitamin C is fruit and to some extent vegetables, the plasma level of vitamin C has been considered a good surrogate or predictor of vitamin C intake by fruit and vegetable consumption. The purpose of this systematic review was to investigate the relationship between dietary vitamin C intakes measured by different dietary methods and plasma levels of vitamin C.

Method: We searched the literature up to May 2006 through the OVID interface: MEDLINE (from 1960) and EMBASE (from 1988). We also reviewed the reference lists in the articles, reviews, and textbooks retrieved. A total of 26 studies were selected and their results were combined using meta-analytic techniques with random-effect model approach.

Results: The overall result of this study showed a positive correlation coefficient between Food Frequency Questionnaire (FFQ) and biomarker (r = 0.35 for "both" genders, 0.39 for females, and 0.46 for males). Also the correlation between Dietary Recalls (DR)/diary and biomarker was 0.46 for "both" genders, 0.44 for females, and 0.36 for males. An overall correlation of 0.39 was found when using the weight record method. Adjusting for energy intake improved the observed correlation for FFQ from 0.31 to 0.41. In addition, we compared the correlation for smokers and non-smokers for both genders (FFQ: for non-smoker r = 0.45, adjusted for smoking r = 0.33).

Conclusion: Our findings show that FFQ and DR/diary have a moderate relationship with plasma vitamin C. The correlation may be affected/influenced by the presence of external factors such as vitamin bioavailability, absorption condition, stress and food processing and storage time, or by error in reporting vitamin C intake.

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Flowchart for study selection.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 1: Flowchart for study selection.

Mentions: The MEDLINE search identified 1016 articles of which 79 articles were potentially relevant. Finally, we chose 26 articles (see Additional file 1) that reported correlation coefficients between plasma levels of vitamin C and dietary intake (see Figure 1). EMBASE provided no more additional studies. One study that reported a negative correlation between dietary intake and plasma level of vitamin C was excluded [26]: a negative relationship between vitamin C intake and plasma vitamin C is biologically implausible. Another study was excluded because of small sample size (n = 5) [27].


Is plasma vitamin C an appropriate biomarker of vitamin C intake? A systematic review and meta-analysis.

Dehghan M, Akhtar-Danesh N, McMillan CR, Thabane L - Nutr J (2007)

Flowchart for study selection.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2200644&req=5

Figure 1: Flowchart for study selection.
Mentions: The MEDLINE search identified 1016 articles of which 79 articles were potentially relevant. Finally, we chose 26 articles (see Additional file 1) that reported correlation coefficients between plasma levels of vitamin C and dietary intake (see Figure 1). EMBASE provided no more additional studies. One study that reported a negative correlation between dietary intake and plasma level of vitamin C was excluded [26]: a negative relationship between vitamin C intake and plasma vitamin C is biologically implausible. Another study was excluded because of small sample size (n = 5) [27].

Bottom Line: A total of 26 studies were selected and their results were combined using meta-analytic techniques with random-effect model approach.An overall correlation of 0.39 was found when using the weight record method.Adjusting for energy intake improved the observed correlation for FFQ from 0.31 to 0.41.

View Article: PubMed Central - HTML - PubMed

Affiliation: Population Health Research Institute, School of Medicine, McMaster University, Hamilton, Canada. mahshid@ccc.mcmaster.ca

ABSTRACT

Background: As the primary source of dietary vitamin C is fruit and to some extent vegetables, the plasma level of vitamin C has been considered a good surrogate or predictor of vitamin C intake by fruit and vegetable consumption. The purpose of this systematic review was to investigate the relationship between dietary vitamin C intakes measured by different dietary methods and plasma levels of vitamin C.

Method: We searched the literature up to May 2006 through the OVID interface: MEDLINE (from 1960) and EMBASE (from 1988). We also reviewed the reference lists in the articles, reviews, and textbooks retrieved. A total of 26 studies were selected and their results were combined using meta-analytic techniques with random-effect model approach.

Results: The overall result of this study showed a positive correlation coefficient between Food Frequency Questionnaire (FFQ) and biomarker (r = 0.35 for "both" genders, 0.39 for females, and 0.46 for males). Also the correlation between Dietary Recalls (DR)/diary and biomarker was 0.46 for "both" genders, 0.44 for females, and 0.36 for males. An overall correlation of 0.39 was found when using the weight record method. Adjusting for energy intake improved the observed correlation for FFQ from 0.31 to 0.41. In addition, we compared the correlation for smokers and non-smokers for both genders (FFQ: for non-smoker r = 0.45, adjusted for smoking r = 0.33).

Conclusion: Our findings show that FFQ and DR/diary have a moderate relationship with plasma vitamin C. The correlation may be affected/influenced by the presence of external factors such as vitamin bioavailability, absorption condition, stress and food processing and storage time, or by error in reporting vitamin C intake.

Show MeSH