Table 1.
Characteristics of studies included in the meta-analysis
| Study | Country | Sample size | Mean duration of follow-up, months | Folic acid food reinforcement | Experimental group (B vitamins supplementation) | Control group | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
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| Sample size | Age, years (mean) | Therapeutic schedule | Male (%) | Sample size | Age, years (mean) | Therapeutic schedule | Male (%) | |||||
| Schnyder, 2002. [23] | Switzerland | 553 | 6 | No | 272 | 63.4±10.6 | Folic acid (1 mg/d), vitamin B12 (cyanocobalamin, 0.4 mg/d), and vitamin B6 (pyridoxine hydrochloride, 10 mg/d) | 79 | 281 | 61.8±11.0 | Placebo | 82 |
| Righetti, 2003. [14] | Italy | 81 | 12 | No | 51 | 64±2 | Folic acid (5 or 15 mg/d) | 45 | 30 | 64±3 | Regular treatment | 43 |
| Toole, 2004. [24] | USA | 3680 | 24 | Yes | 1827 | 66.4±10.8 | Folic acid (2.5 mg/d), vitamin B12 (0.4 mg/d), and vitamin B6 (25 mg/d) | 62 | 1853 | 66.2±10.8 | Folic acid (0.02 mg/d), vitamin B12 (6 micro g/d), and vitamin B6 (0.2 mg/d) | 62 |
| Wrone, 2004. [25] | USA | 510 | 24 | Yes | 342 | 59.5±15.4 | Folic acid (5 or 15 mg/d) | 50 | 168 | 61.3±14.6 | Folic acid (1 mg/d), | 50 |
| Liem, 2005. [15] | The Netherlands | 593 | 42 | No | 300 | NA | Folic acid (0.5 mg/d) | NA | 293 | NA | Regular treatment | NA |
| Zoungas, 2006. [16] | Australia | 315 | 43 | Yes | 156 | 56±13 | Folic acid (15 mg/d) | 73 | 159 | 56±14 | Placebo | 63 |
| Bonaa, 2006. [7] | Norway | 2815 | 36 | No | 1872 | 63.2±11.7 | Folic acid (0.8 mg/d), vitamin B12 (0.4 mg/d), and vitamin B6 (40 mg/d) | 73 | 943 | 62.6±11.4 | Placebo | 75 |
| Lonn, 2006. [8] | Canada | 5522 | 60 | Yes | 2758 | 68.8±7.1 | Folic acid (2.5 mg/d), vitamin B12 (1 mg/d), and vitamin B6 (50 mg/d) | 71 | 2764 | 68.9±6.8 | Placebo | 71 |
| Righetti, 2006. [12] | Italy | 88 | 29 | No | 37 | 63.9±1.6 | Folic acid (5 mg/d) | 65 | 51 | 65.1±1.9 | Regular treatment | 49 |
| Jamison, 2007. [6] | USA | 2056 | 38 | Yes | 1032 | 65.4±12.0 | Folic acid (40 mg/d), vitamin B12 (2 mg/d), and vitamin B6 (100 mg/d) | 98 | 1024 | 66.2±11.5 | Placebo | 98 |
| Heijer, 2007. [17] | The Netherlands | 701 | 36 | No | 353 | NA | Folic acid (5 mg/d), vitamin B12 (0.4 mg/d), and vitamin B6 (50 mg/d) | 52 | 348 | NA | Placebo | 51 |
| Albert, 2008. [13] | USA | 5442 | 87 | Yes | 2721 | 62.8±8.8 | Folic acid (2.5 mg/d), vitamin B12 (1 mg/d), and vitamin B6 (50 mg/d) | NA | 2721 | 62.8±8.8 | Placebo | NA |
| Mann, 2008. [10] | Canada | 619 | 60 | Yes | 307 | 72.2±6.6 | Folic acid (2.5 mg/d), vitamin B12 (1 mg/d), and vitamin B6 (50 mg/d) | 67 | 312 | 72.2±6.5 | Placebo | 66 |
| Ebbing, 2008. [9] | Norway | 2319 | 38 | No | 1540 | 61.4±10.1 | Folic acid (0.8 mg/d), vitamin B12 (0.4 mg/d), and vitamin B6 (40 mg/d) | 80 | 779 | 62.0±9.9 | Placebo | 77 |
| Armitage, 2010. [11] | The United Kingdom | 12064 | 80 | No | 6033 | NA | Folic acid (2 mg/d), vitamin B12 (1 mg/d) | 83 | 6031 | NA | Placebo | 83 |