DENVER, COLORADO. Researchers at the University of Colorado School of Pharmacy warn that prolonged use of acid-suppressing drugs such as cimetidine (Tagamet), ranitidine (Zantac) and omeprazole (Losec) can lead to a serious vitamin B12 deficiency. They cite the case of a 78-year-old non-vegetarian, white woman with GERD (gastroesophageal reflux disease) who had been taking cimetidine or ranitidine for 4.5 years. She was started on cimetidine (300 mg four times daily) in February 1990, which was changed to ranitidine (150 mg twice daily) in April 1993. Her vitamin B12 level was normal (413 pg/mL) in August 1992, but by June 1994 it had decreased to 256 pg/mL and her homocysteine level had increased dramatically to 27.3 micromol/L. Note: A homocysteine level above 10 micromol/L vastly increases the risk of atherosclerosis and stroke with a 5 micromol/L increase corresponding to a 70 per cent increase in the risk of heart disease and a 50 per cent increase in stroke risk.
The patient was started on 1000 micrograms/day of sublingual vitamin B12 supplementation and by
November 1994 her level was back up to 517 pg/mL and her homocysteine level was down to 20.3
micromol/L. Further improvements were observed in March 1998 when her vitamin B12 level was up to 629
pg/mL and homocysteine was down to 13.9 micromol/L. The researchers point out that other studies have
shown that omeprazole also lowers vitamin B12 levels and conclude that older people on long-term acid-
suppressing drugs should be monitored for vitamin B12 deficiency and supplement if necessary.