Components of variation in serum carotenoid concentrations: the Polyp Prevention Trial

Abstract

Objectives: The intra-and interindividual variations and season and center effects were estimated from a series of serum carotenoid concentrations in the Polyp Prevention Trial (PPT) participants. Subjects/Methods: Fasting blood was collected annually for 4 years in all 1905 participants, and a subcohort of 901 participants were selected within each (of eight) center(s), by gender and dietary arm of the study, for measurement of five major carotenoid peaks. Using variance of component methods, the variation in serum carotenoid concentrations about the underlying mean was partitioned into explanatory components attributed to various sources. Results: The contributions of the inter-and intraindividual variances to the overall variation in carotenoid concentrations were in the range of 61-70 and 20-35%, respectively, whereas center and center-by-season effects provided 2.6-9.5 and 0.2-1.4%, respectively. The highest percent (35%) of intraindividual variation was exhibited by lycopene, and the highest percent (70% apiece) of interindividual variation was exhibited by lutein/zeaxanthin and b-carotene. Serum lycopene had the highest ratio of intra-to interindividual variation of 0.57, whereas lutein had the lowest ratio of 0.29. We estimate that the ratio of intrato interindividual variance around the mean carotenoid concentration can be reduced greatly by collecting 3-4 compared to 1 blood measurement in large-scale trials like the PPT. Conclusion: In the largest study of components of variation in individuals at high risk for colorectal cancer, the largest contributors to variation in serum carotenoid concentrations were intra-and interindividual effects followed by center and center-by-season effects.

Plasma Alkylresorcinols Reflect Important Whole-Grain Components of a Healthy Nordic Diet

“…Various explanations for this lack of response in plasma b-carotene concentration are possible. First, the change in b-carotene intake may be too small to be reflected in a significant change in plasma b-carotene concentration, possibly because of the high intra-and interindividual variations in both the intake and plasma concentration of b-carotene (55). In addition, in intervention studies where significant responses have been observed, increases in b-carotene intake were greater (31,33), and although it would be expected that such an increase would increase concentration, it may not because of variations in the bioavailability of b-carotene from different diets (34).…”

Vitamin A and D Deficiencies Associated With Incident Tuberculosis in HIV-Infected Patients Initiating Antiretroviral Therapy in Multinational Case-Cohort Study

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