Table 3 Overview: trial and intervention details

Andreeva et al. [52]^a

France

RCT

871

Folate, vitamin B₆, vitamin B₁₂

Daily:

Folate 0.56 mg

B₆ 3 mg

B₁₂ 0.02 mg

4 years

End of treatment

Brady et al. [53]

The USA

RCT

659

Folate, vitamin B₆, vitamin B₁₂

Daily:

Folic acid 40 mg

B₆ 100 mg

B₁₂ 2 mg

5 years

After 4 and 5 years of treatment

Bryan et al. [39]

Australia

RCT

211

Folate, B₆, B₁₂

Daily:

Folate 750 μg

Or daily:

B₆ 20 mg

Or daily:

B₁₂ 15 μg

5 weeks

End of treatment

Chan et al. [40]

The USA

RCT

115

Nutriceutical formula also containing folic acid and B₁₂

Daily:

Folic acid 400 μg, B₁₂ 6 μg

3 months

End of treatment

Cockle et al. [41]

The UK

RCT

139

Multivitamin supplement also containing folic acid, B₆, B₁₂

Daily:

Folic acid 600 mg, B₆ 22 mg, B₁₂ 0.03 mg

24 weeks

End of treatment

Dangour et al. [47]

The UK

RCT

201

B₁₂

Daily:

B₁₂ 1 mg

1 year

End of treatment

Durga et al. [49]

Netherlands

RCT

818

Folic acid

Daily:

Folic acid 800 μg

3 years

End of treatment

Eussen et al. [48]

Netherlands

RCT

195

Vitamin B₁₂ or vitamin B₁₂ + folate

Daily:

B₁₂ 1000 μg

Or daily:

B₁₂ 1000 μg

Folic acid 400 μg

24 weeks

End of treatment

Ford et al. [54]

Australia

RCT

299

Folic acid, vitamin B₆, vitamin B₁₂

Daily:

Folic acid 2 mg

B₆ 25 mg

B₁₂ 400 μg

2 years

End of treatment

Hankey et al. [55]^a

Netherlands

RCT

2214

Folic acid, vitamin B₆, vitamin B₁₂

Daily:

Folic acid 2.5 mg

B₆ 25 mg

B₁₂ 500 μg

3.4 years

End of treatment

Kang et al. [56]

The USA

RCT

2009

Folic acid, vitamin B₆, vitamin B₁₂

Daily:

Folic acid 2.5 mg

B₆ 25 mg

B₁₂ 500 μg

6.6 years

End of treatment

Kwok et al. [57]

China

RCT

271

Vitamin B₁₂

Daily:

B₁₂ 1000 μg

27 months

End of treatment

Lewerin et al. [42]

Sweden

RCT

195

Folate, vitamin B₆, vitamin B₁₂

Daily:

Folate 0.8 mg

B₆ 3 mg

B₁₂ 0.5 mg

4 months

End of treatment

McMahon et al. [50]

New Zealand

RCT

276

Folate, vitamin B₆, vitamin B₁₂

Daily:

Folate 1000 μg

B₆ 10 mg

B₁₂ 500 μg

2 years

End of treatment

Pathansali et al. [43]

The UK

RCT

24

Folic acid

Daily:

Folic acid 5 mg

4 weeks

End of treatment

Pipingas et al. [44]

Australia

RCT

138

Multivitamin formula also containing folic acid, vitamin B₆, and vitamin B₁₂

Daily:

Folic acid 500 μg

B₆ 41.14 mg

B₁₂ 50 μg

16 weeks

End of treatment

Stott et al. [58]^a

The UK

RCT

23

Folic acid, vitamin B₆, and vitamin B₁₂ as one of various combinations

Daily:

Folic acid 2.5 mg

B₆ 25 mg

B₁₂ 400 μg

12 weeks

After 1 year

Van der Zwaluw et al. [51]

Netherlands

RCT

2919

Folic acid, vitamin B₁₂

Daily:

Folic acid 400 μg

B₁₂ 500 μg

2 years

End of treatment

Walker et al. [45]

Australia

RCT

900

Folic acid, vitamin B₁₂

Daily:

Folic acid 400 μg

B₁₂ 100 μg

2 years

End of treatment

Wolters et al. [46]

Germany

RCT

220

Multivitamin capsules also containing folic acid, vitamin B₆, and vitamin B₁₂

Daily:

Folic acid 400 μg

B₆ 3.4 mg

B₁₂ 9 μg

6 months

End of treatment