Dear Doc: Causes of vitamin B12 deficiency
Vail CO, Colorado
Editor’s note: This is part two in a series on B12 deficiency.
I’ve been tired and dizzy lately. I have a healthy diet and try to exercise when I can. I was told I should get my B12 level checked because I might be deficient. What does that mean?
Tired in Eagle
The list of vitamin B12 deficiency related symptoms is broad and rather general, so I would not suggest running to your doctor if you woke up feeling just a bit fatigued or if this is the first time you forgot where you left your car keys. B12 deficiency nevertheless seems to be under recognized.
In a study published in the Journal of the American Geriatrics Society, it was estimated that 15 percent of adults over the age of 65 have vitamin B12 deficiency. It is unclear whether this is a result of dietary changes, decreased intestinal absorption, or the widespread use of proton pump inhibitors like Prilosec, which may cause decreased vitamin B12 absorption. Another study found similar rates of B12 deficiency in groups of individuals as young as 29 years old. The major difference was the younger group’s general lack of symptoms. Despite this growing evidence of the prevalence of vitamin B12 deficiency however, there are no recommendations for routine testing.
Vitamin B12 is found in foods such as shellfish, red meat, fish and dairy products.
Many cereals and most multivitamins contain vitamin B12. The Recommended Daily Allowance or RDA is 2.4 micrograms per day for adults. Children need less, while pregnant and breast feeding women need more. As I have mentioned before, our RDA recommendations were established years ago and may be too low. New information recently released indicates that higher than average B12 levels seem to protect older adults against dementia. It raises interesting questions about all our levels. Common causes of vitamin B12 deficiency are:
– Vegetarian diets
– The use of acid lowering medications, both prescription and over the counter
– The use of metformin to treat diabetes
– Intestinal surgery involving the terminal portion of the ileum
– Gastric bypass surgery
– Lack of intrinsic factor, which is needed to absorb B12
– Crohn’s disease
Unlike some other vitamins and supplements, vitamin B12 has a very low potential for toxicity. In fact, no adverse symptoms have been associated with vitamin B12 supplementation. That is probably one of the reasons vitamin B12 injections were so commonly used in medical practices years ago. Again, maybe they were on to something back then. In the United States, vitamin B12 deficiency is defined as a measured blood level below 200 pg/ml. That level is well recognized as the level at which pernicious anemia develops. Levels falling into the “normal” range in America may still be associated with neurological and other problems, however. For this reason, several countries in Europe and Asia have set their low range of B12 as 500-550 pg/ml, over twice as high as the low levels in the United States.
Although shots are certainly effective in raising vitamin B12 levels, newer evidence suggests that oral supplementation may be effective for most individuals. Oral B12 can be found over the counter as a capsule in doses of 500 to 1000 mcg as well as in similar doses as a sublingual tablet to be dissolved under the tongue. Both forms are equally effective for most people. However, if you have a lack of intrinsic factor, have had gastric or intestinal surgery, or take metformin or an acid blocker, then the sublingual tablet may be better for you.
B12 deficiency typically takes years to develop and months to correct. Although some people do feel better soon after supplementation begins, you should not necessarily expect to feel an immediate change. Perhaps most of all, consider this information about an old supplement as a part of your healthy lifestyle decision making.
On a last note, homecoming season is upon us. Please have fun, enjoy the games and festivities, but always be safe. Don’t drink and drive! Go Devils!
Let me know what’s on your mind at firstname.lastname@example.org. I’d love to hear!
Remember your health is your responsibility! Health is our greatest asset and it doesn’t happen by accident. If something doesn’t seem right, or questions are left unanswered don’t wait, call your doctor.
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