No trials of vitamin B6 involving people with cognitive impairment or dementia were found.
The two trials included in the review (Bryan 2002; Deijen 1992) used a double-blind, randomized, placebo-controlled design and involved 109 healthy older people. One trial restricted enrolment to women and the other to men.
Vitamin B6 supplementation and healthy older women:
Bryan 2002, enrolled 211 healthy women from various age groups into a five-week study. The trial was of multifactorial design with folic acid, vitamin B12, vitamin B6 and placebo in its four arms. Twelve healthy women aged 65 to 92 years received 75 mg vitamin B6 orally per day and were compared with 21 healthy women who were allocated to placebo. No statistically significant benefits from vitamin B6 on mood or cognition were observed.
Vitamin B6 supplementation and healthy older men:
Deijen 1992, recruited 76 healthy men aged 70 to 79 years. They were divided into 38 matched pairs, one member of each pair randomly allocated to 20 mg of vitamin B6 (pyridoxine hydrochloride) per day for 12 weeks the other to placebo. No statistically significant differences between treatment and placebo were found in their effects on cognition or mood.
Effect of vitamin B6 supplementation on vitamin B6 status:
Deijen 1992, reported that 20 mg of pyridoxine hydrochloride per day for 12 weeks increased blood vitamin B6 activity as assessed as by plasma pyridoxal-5'-phosphate (WMD 238, 95%CI 211.58 to 264.42, P<0.00001) and erythrocyte enzyme asparate aminotransferase (WMD 0.43, 95%CI 0.30 to 0.56, P<0.00001)
Effect of vitamin B6 supplementation on blood homocysteine concentration:
Neither of the included trials measured homocysteine levels.
Drop-outs:
All participants allocated to vitamin B6 or placebo completed the trial protocol.
Adverse events:
No adverse effects were reported.
Effect of vitamin B6 on carer burden, care costs and institutionalization rate:
We found no trials in which these outcomes were assessed.
