Table 1 inclusion and exclusion criteria for the B-PROOF study

Men and women, aged 65 years and older

Immobilization: being bedridden or wheelchair bound

Compliance for tablet intake of > 85% 4-6 weeks prior to start of the trial

Cancer diagnosis within the last 5 year, except skin cancer as basal cell carcinoma and squamous cell carcinoma

Competent to make own decisions

Serum creatinine level > 150 μmol/L

Elevated homocysteine level (≥ 12 μmol/L and ≤ 50 μmol/L)

Current or recent (< 4 months) use of supplements with very high doses of vitamin B₁₂ (intramuscular injections) or folic acid (> 300 μg)

Participation in other intervention studies