Table 4.
Summary of Randomised Controlled Trials of 2 years or more assessing the effect of B vitamins on cognitive function in ageing.
| Author/Year/Trial | Country | Sample Size (n) | Age (Years) | Population Studied Plasma tHcy (µmol/L) |
Treatment (mg/day) | Duration | Cognitive Outcomes |
|---|---|---|---|---|---|---|---|
| Questionnaire based assessment | |||||||
| McMahon 2006 [191] | New Zealand | 276 | ≥65 | Healthy tHcy > 13 |
1.0 FA, 0.5 B12, 10 B6 | 2 years | No significant effect on cognition |
|
FACIT Durga 2007 [186] |
The Netherlands | 818 | 50–70 | Healthy tHcy 13–26 |
0.8 FA or placebo | 3 years | Improvement in domains including memory, information-processing and sensorimotor speed No improvement in global cognition or domains of complex speed or word fluency |
|
WAFACS Kang 2008 [190] |
USA | 2009 | ≥65 | CVD/high risk women tHcy not provided |
2.5 FA, 1.0 B12, 50 B6 or placebo | 6.6 years | Reduced risk of cognitive decline among women with low baseline dietary intake of B-vitamins Overall no significant effect on rate of cognitive decline |
| Brady 2009 [193] |
USA | 659 | Mean 67.3 | Advanced renal disease tHcy ≥ 15 |
40 FA, 2.0 B12, 100 B6 or placebo | 5 years | No significant effect on cognition |
|
Health in Men Study: sub set Ford 2010 [194] |
Australia | 299 | ≥75 | Hypertensive men Mean tHcy 13.1–14 |
2.0 FA, 0.4 B12, 25 B6 or placebo | 2 years | No significant effect on cognition |
| Kwok 2011 [189] |
Hong Kong | 140 | ≥60 | Dementia diagnosis Mean tHcy 14.1 |
5.0 FA, 1.0 B12 or placebo | 2 years | Improvement in domain of construction No change in global cognitive decline, attention, memory or conceptualisation |
|
Beyond ageing project Walker 2012 [187] |
Australia | 900 | 60–74 | Elevated psychological distress Mean tHcy 9.7 |
0.4 FA, 0.1 B12 or placebo | 2 years | Improvement in overall global cognition and in domains of immediate and delayed recall scores No significant change in other cognitive domains |
|
VITACOG De Jager 2012 [195] |
UK | 168 | ≥70 | MCI Mean tHcy 11.3 |
0.8 FA, 0.5 B12, 20 B6 or placebo | 2 years | Slower decline in global cognition and in domains of semantic and episodic memory Clinical benefit in global clinical dementia rating score |
|
BPROOF Van Der Zwaluw 2014 [185] |
The Netherlands | 2919 | ≥65 | Healthy tHcy 12–50 |
0.4 FA, 0.5 B12, 0.15 D3 or placebo + D3 | 2 years | Slower rate of decline in global cognition No change in domains of memory |
| Brain-imaging assessment | |||||||
|
VITACOG Smith 2010 Douaud 2013 [188,196] |
UK | 168 | ≥70 | MCI Mean tHcy 11.3 |
0.8 FA, 0.5 B12, 20 B6 or placebo | 2 years | Slowed shrinkage of brain Marked reduction in cerebral atrophy in grey matter regions |
|
BPROOF Van Der Zwaluw 2014 [185] |
The Netherlands | 2919 | ≥65 | Healthy tHcy 12–50 |
0.4 FA, 0.5 B12, 0.15 D3 or placebo + D3 | 2 years | Awaiting MRI scan results |
Abbreviations: tHcy, homocysteine; FA, folic acid; MMA, methylmalonic acid; holoTC, holo-transcobalamin; EPA, eicosapentaenoic; DHA, docosahexaenoic acid; MCI, mild cognitive impairment; MRI, magnetic resonance imaging; CVD, cardiovascular disease.