Fan 2017.

Methods	2‐arm, parallel group, randomised, controlled trial, 6 months duration.
Participants	Location: China, Shandong (Weifang), single centre. Setting of recruitment and treatment: community. Sample size Number randomised: 40 in intervention, 40 in comparator. Number completed: 38 in intervention, 37 in comparator. Participant baseline characteristics: Age in years (mean ± SD) : intervention 65.45 ± 2.89, comparator 66.37 ± 1.93. Female sex : intervention 20/40 (50%), comparator 22/40 (55%). Cognitive function ‐ MMSE score (mean ± SD): intervention 24.88 ± 0.93, comparator 24.61 ± 0.85. Inclusion criteria: Complaints of memory issues by participant, family members, or others who are well‐informed; Mini‐Mental State Examination (MMSE) score ≤ 26; Global Deterioration Scale (GDS) grade 2 to 3, Activities of Daily Living (ADL) score ≤ 18; Cognitive impairment > 3 months; Memory test results 1.5 standards deviations below normal controls matched for age and education; Aged 60 to 75 years. Exclusion criteria: Diagnosed with dementia, or any other disease which leads to brain function disorder; Severe disease of heart, liver, lung, kidney etc., severe anaemia, severe malnutrition, thyroid problem, or folic acid deficiency; Severe vision and hearing impairment; Taken folic acid supplement within last month.
Interventions	Intervention: 400 µg folic acid per day orally for 6 months. Comparator group: No intervention, maintenance of their usual lifestyle and eating habits. Use of additional interventions (common to both treatment arm): not reported.
Outcomes	Overall cognitive function: MMSE (also measured: MoCA). Functional performance: Activities of Daily Living (ADL) scale.
Source of Funding	Not reported.
Declaration of Interest	No declarations.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random number table “按随机数字表法将受试对象随机分为对照组和干预组，每组４０例。” (page 4161)
Allocation concealment (selection bias)	Unclear risk	No information
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not blinded. On the first day of each month, subjects in the experimental group were given a bottle of folic acid (400μg/tablet, 30 tablets/bottle) by research staff in community. They were instructed to take one tablet per day. Research staff contacted participants regularly and recorded the usage of folic acid in the intervention group. No mention of contact with comparator group. “干预组每月第１天由社区服务站相关人员统一发放规格为每片４００μｇ的叶酸１瓶（３０片），每天服用１片，持续６个月，定期回访，询问叶酸服用情况并记录。” “对照组不进行任何干预，维持原有的生活、饮食习惯。” (page 4161)
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information
Incomplete outcome data (attrition bias) All outcomes	Low risk	75/80 (94%) completed trial. 3 dropped out in control arm, and 2 dropped out in intervention arm. 2 cases excluded for missing more than 5 doses, 3 cases voluntary dropout, group allocations not reported. Results reported only for the 75 participants who completed the trial.
Selective reporting (reporting bias)	Low risk	Results were reported for all outcomes mentioned in the Methods section of paper. No protocol identified.
Other bias	Low risk	No other sources of bias identified.