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. Author manuscript; available in PMC: 2007 Oct 31.
Published in final edited form as: Am J Clin Nutr. 2006 Nov;84(5):1093–1101. doi: 10.1093/ajcn/84.5.1093

TABLE 3.

Baseline values and estimated percentage within-person changes from baseline in adjusted urinary arsenic metabolites over time1

Folate group (n = 96) Placebo group (n = 98) P for treatment × time interaction2
log (%InAs) 0.0068
 Baseline 2.66 ± 0.033 2.63 ± 0.03
 Change up to week 1 (%) −0.15 ± 0.044 −0.06 ± 0.03
 Change up to week 12 (%) −0.31 ± 0.045 −0.13 ± 0.044
% MMA <0.0001
 Baseline 12.55 ± 0.34 13.27 ± 0.41
 Change up to week 1 (%) −1.6 ± 0.265 0.43 ± 0.31
 Change up to week 12 (%) −2.6 ± 0.375 −0.71 ± 0.43
% DMA 0.0029
 Baseline 72.02 ± 0.67 71.74 ± 0.75
 Change up to week 1 (%) 2.8 ± 1.036 0.48 ± 0.57
 Change up to week 12 (%) 5.9 ± 0.825 2.14 ± 0.716
PMI7 0.4639
 Baseline 0.94 ± 0.04 0.97 ± 0.03
 Change up to week 1 (%) 0.04 ± 0.03 0.08 ± 0.048
 Change up to week 12 (%) 0.11 ± 0.058 0.13 ± 0.056
SMI9 <0.0001
 Baseline 6.46 ± 0.21 6.42 ± 0.31
 Change up to week 1 (%) 1.25 ± 0.185 0.04 ± 0.26
 Change up to week 12 (%) 2.88 ± 0.435 0.40 ± 0.32
1

Values were derived from fitted linear models with repeated measures after adjustment for sex, age, betel nut use, water arsenic, and urinary creatinine.

%

InAs, %MMA, and %DMA, the proportion of total urinary arsenic excreted as inorganic arsenic, monomethylarsonic acid, and dimethylarsinic acid, respectively; PMI, primary methylation index; SMI, secondary methylation index. The groups did not differ significantly before supplementation.

2

Based on a generalized score test.

3

x̄ ± SE (all such values).

4–6,8

Significant within-person change over time (Wald test on relevant model coefficients): 4P < 0.001, 5P < 0.0001, 6P < 0.01, 8P < 0.05.

7

Significant effect of time, P = 0.0029. Measured as the ratio of MMA to InAs.

9

Measured as the ratio of DMA to MMA.