Although sublingual B-12 is often promoted for better absorption, there does not appear to be much evidence for this. In fact, one clinical study comparing the same amount of B-12 given orally or sublingually
found they were equally effective at correcting B-12 deficiency over a two-month period.
Be aware that sublingual B-12 supplements often contain sugar substitutes such as sorbitol, mannitol or sucralose, which can cause gastrointestinal symptoms
in some people.
It should also be noted that unlike the vitamin B-12 in foods, the purified form of B-12 found in supplements, including tablets, does not require stomach acid for absorption -- a potential concern for people with low stomach acid (including many people over the age of 50) or those who take acid blockers such as Pepcid or Zantac, or proton pump inhibitors such as Prevacid, or Prilosec, who are at an increased risk for B-12 deficiency
. For those who have difficulty with large pills, keep in mind that only a very small amount of B-12 is required to meet the recommended daily intake
and can be obtained in small tablets (including some tested by ConsumerLab.com in its B Vitamins Supplement Review). For more information about buying and using B-12 supplements, plus our tests of popular products, see the B Vitamins Supplements Review >>
Learn More About Vitamin B-12
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Is it better to get vitamins from foods or supplements, and are natural vitamins better than synthetic vitamins? >>
I take omeprazole (Prilosec), a proton pump inhibitor, to reduce stomach acid. Are there supplements I should avoid, or be taking, due to this drug? >>
I read on your website that some B-12 vitamins can cause diarrhea due to added sugar substitutes like sorbitol. I have had diarrhea and never thought it could be caused by my vitamin B-12 supplement, until I read your article and stopped taking the supplement. My diarrhea stopped immediately. Can you help me find a brand of B-12 that doesn't contain sorbitol or sugar substitutes that could cause this problem? >>
This CL Answer initially posted on 9/9/2015.
Last updated 8/2/2017.