Table 5.

Description of studies conducted among older adults (≥65 years)

Author year Country	Design	B12 dose or exposure	Dietary assessment methods	Participants N	Age at inclusion	Follow-up time	Outcome	Baseline B12 status
Seal 2002 Australia (26)	RCT	10, 50 μg/d vs. placebo	N/A	31	Mean 81.4 years	4 weeks	s-B12, Hcy	s-B12 100–150 pmol/L
Eussen 2005 Netherlands (27)	RCT	2.5, 100, 250, 500 and 1000 μg/d	N/A	120	Mean 80 years	16 weeks	s-B12, p-MMA, p-tHcy, p-holoTC	s-B12 100–300 pmol/L
Dhonokushe-Rutten 2005 Netherlands (28)	RCT	Milk: 7000 μg B12/L vs. placebo Capsules: 1000 μg/d vs. placebo	N/A	Milk: 20 Capsules: 23 Placebo milk: 21 Placebo capsules: 14	Mean 81–82 years	12 weeks	s-B12, p-MMA, p-tHcy	S-B12 100–300 pmol/L and p-MMA ≥0.30 μmol/L
Favrat 2011 Switzerland (29)	Pragmatic RCT, parallel	1000 μg/d vs. placebo	N/A	50	Median 75.5 years	1 month	s-B12, s-MMA, s-tHcy	s- B12 125-200 pM/L
Hill 2013 UK (30)	RCT, parallel	500, 100 and 10 μg/d vs. placebo	N/A	100	Median 71 years	2 months	p-B12, p-MMA, p-tHcy, s-holoTC	p-B12 <250 pmol/L, MMA/mmol creatinine >1.5
Rajan 2002 USA (31)	Nonrandomized intervention	25 μg/d for 6 weeks, 100 μg/d for 6 weeks, 1000 μg/d for 6 weeks	N/A	40	65 years or older, mean age 79 years	18 weeks	s-MMA, s-tHcy	s-B12 <221 pmol/L and s-MMA >271 nmol/L
Stabler 2006 USA (32)	RCT	0, 25 or 100 μg/d	N/A	149 (45 with elevated MMA)	Mean 76.3 years	3 months	s-B12, s-MMA, s-tHcy	s-MMA <271 (all >271 offered 1000 μg/d)
Jungert 2020 Germany (33)	Prospective cohort	Cobalamin from diet and supplements	3-day dietary record	332	Age of at least 60 years (median 68 years)	12 years	s-B12	N/A