Table 3.
Results of studies conducted in people with As exposure and supplementation with folic acid or zinc.
| Reference | Research Model | Study Description | Main Results |
|---|---|---|---|
| Gamble et al., 2007 [45] | Bangladesh, adults | CG (n = 62)—placebo (orally, for 12 weeks) G1 (N = 68)—folic acid 400 µg/day (orally, for 12 weeks) |
G1 vs. CG blood: MMA↓, tAs↓, DMA↔ urine: DMA↑ (after 1 week) DMA↔(after 12 week) |
| Bozack et al., 2019 [46] | Bangladesh, adults | CG (n = 90)—placebo (orally, for 12 weeks) G1 (n = 133)—folic acid 400 µg/day (orally, for 12 weeks) G2 (n = 129)—folic acid 800 µg/day (orally, for 12 weeks) |
G1, G2 vs. CG plasma: folate↑, homocysteine↓ RBC folate↑ urine: %iAs↓, %MMAs↓, %DMAs↑ |
| G2 vs. G1 urine: %MMAs↓ | |||
| G1 (n = 68)—folic acid 400 µg/day (orally, for 12 weeks) and after that placebo (orally, for 12 weeks) G2 (n = 60)—folic acid 800 µg/day (orally, for 12 weeks) and after that placebo (orally, for 12 weeks) G1a (n = 65)—folic acid 400 µg/day (orally, for 24 weeks) G2a (n = 69)—folic acid 800 µg/day (orally, for 24 weeks) |
G1a, G2a vs. G1, G2 urine: %iAs↓, %MMAs↓, %DMAs↑ |
||
| Peters et al., 2015 [47] | Bangladesh, adults | CG (n = 102)—placebo (orally, for 12 weeks) G1 (n = 153)—folic acid 400 µg/day (orally, for 12 weeks) G2 (n = 151)—folic acid 800 µg/day (orally, for 12 weeks) |
G1 vs. CG plasma folate↑, RBC folate↑, geometric mean of blood tAs↑, percentage decline in geometric mean blood tAs from baseline↓ |
| G2 vs. CG plasma folate↑, RBC folate↑, geometric mean of blood tAs↓, percentage decline in geometric mean blood tAs from baseline↑ | |||
| CG (n = 102)—placebo (orally, for 24 weeks) G1 (n = 76)—folic acid 400 µg/day (orally, for 12 weeks) and after that placebo (orally, for 12 weeks) G2 (n = 74)—folic acid 800 µg/day (orally, for 12 weeks) and after that placebo (orally, for 12 weeks) G1a (n = 77)—folic acid 400 µg/day (orally, for 24 weeks) G2a (n = 77)—folic acid 800 µg/day (orally, for 24 weeks) |
G2, G2a vs. CG geometric mean of blood tAs↓ |
||
| G1a vs. G1 geometric mean of blood tAs↔, percentage decline in geometric mean of urinary and blood tAs↔ | |||
| G2a vs. G2 geometric mean of blood tAs↔, percentage decline in geometric mean of urinary and blood tAs↔ | |||
| Bozack et al., 2020 [48] | Bangladesh, adults | CG (n = 104)—placebo (orally, for 12 weeks) G1 (n = 156)—folic acid 400 µg/day (orally, for 12 weeks) G2 (n = 154)—folic acid 800 µg/day (orally, for 12 weeks) |
G1 vs. CG participants with betaine concentrations below the median: urine: decreases in ln(%iAs)↑, decrease in %MMAs↑, increases in %DMAs↑ |
| G2 vs. CG participants with betaine concentrations below the median: urine: decreases in ln(%iAs)↑, increases in %DMAs↑ | |||
| Kordas et al., 2017 [49] | Mexico, children (6–7 years) | CG (n = 151)—placebo (orally, for 6 months) G1 (n = 144)—zinc oxide 30 mg/day (orally, for 6 months) |
G1 vs. CG urine: %DMA↓, %MMA↔, %iAs↔, tAs↔ |
| Hall et al., 2016 [50] | Bagladesh, adults | CG (n = 101)—placebo (participants received arsenic-removal water filters and had been drinking water from wells with water As concentration >50 µg/L at least 3 years) G1 (n = 152)—folic acid 400 µg/day (orally, for 12 weeks) and after that placebo (participants received arsenic-removal water filters and had been drinking water from wells with water As concentration >50 µg/L at least 3 years) G2 (n = 149)—folic acid 800 µg/day (orally, for 12 weeks) and after that placebo (participants received arsenic-removal water filters and had been drinking water from wells with water As concentration >50 µg/L at least 3 years) |
G1, G2 vs. CG plasma: choline↑, betaine↑, percentage decrease in DMG↑ |
| G1 vs. G2 plasma: choline↔, betaine↔, percentage decrease in DMG↔ | |||
| Dani, 2019 [51] | Women (16 year-old)—chronic arsenic intoxication | ex juvantibus therapy: torasemide 10–20 mg/day, thiamine 300 mg/day, magnesium 5 mg/day, folic acid 5 mg/day and metamizole and simeticon (on-demand) | nuchal scalp hair shafts: As—undetectable morning urine: As—undetectable afternoon urine: As 50 nmol/L symptoms (leg cramps, abdominal pains)↓ |
| Howe et al., 2017 [52] | Bangladesh, adults | CG (n = 104)—placebo (orally, for 12 weeks) G1 (n = 156)—folic acid 400 µg/day (orally, for 12 weeks) |
G1 vs. CG blood: PTHMs↔ |
| Ghose et al., 2014 [53] | India, patients with symptoms of arsenic toxicity | CG (n = 45)—drinking arsenic free water (orally, for 6 months) G1 (n = 32)—folic acid 5 mg/day (orally, for 6 months) |
G1 vs. CG skin score↓, systemic disease score↑ (overall: clinical symptoms of arsenicosis↓) |
↑—significant increase; ↓—significant decrease; ↔—no significant changes; CG—control group; DMA—dimethylarsinic acid; DMAs—dimethyl arsenical species; DMG—dimethylglycine; G1—group 1; G2—group 2; iAs—inorganic arsenic; MMA—monomethylarsonic acid; MMAs—monomethyl arsenical species; PTHMs—post-translational histone modifications; RBC—red blood cell; tAs—total arsenic species.