Vitamin B-12 has dozens of roles in your system, from supporting blood functions to boosting your brain power. It's no wonder that you might consider taking a B-12 pill. Although B-12 is considered safe, even in large doses, you'll need to let your doctor know if you decide to take it. If you're taking medications, some of them may interact poorly with B-12 pills.
Vitamin B-12 is bound to protein in foods until hydrochloric acid in your stomach pulls it off, getting it ready for absorption. If you are older, have been through a gastrointestinal surgery or are taking medications for gastroesophageal reflux disease, you might not have adequate amounts of hydrochloric acid in your stomach. In these cases, B-12 might not be separated from protein, leaving it unavailable to be absorbed. B-12 in supplements, however, isn't bound to proteins and is already free to be absorbed. Thus even if you aren't producing enough stomach acid, your body can probably still utilize the B-12 from your supplement.
Your daily B-12 pill can help prevent some of the issues with anemia. Because one of B-12's roles is to create healthy new red blood cells, when your B-12 level drops, your system could create abnormally shaped red blood cells. This condition, known as megaloblastic anemia, inhibits oxygen transportation to cells and affects brain functions. You could become confused, weak, have poor memory and experience difficulty with your balance. While megaloblastic anemia isn't common since your body stores plenty of B-12, if you have absorption issues or follow a strict vegetarian diet, minimizing your intake of B-12-rich animal foods, your B-12 level could plummet.
When the amino acid known as homocysteine builds up in your body, your risk of cognitive decline and dementia increases. Researchers from the University of Oxford in the United Kingdom evaluated the benefits of the B vitamins on improving homocysteine levels. In the study, published in 2013 in "Proceedings of the National Academy of Sciences of the United States of America," study participants were given a high-dose B-vitamin mixture, including 0.8 milligram of folic acid, 20 milligrams of B-6 and 0.5 milligram of B-12. As compared to the control group, participants who took the extra B vitamins showed a slowed rate of brain shrinkage and decreased levels of homocysteine over the two-year period. The combination of B-12 with the other B vitamins is believed to help preserve brain tissue, minimizing cognitive decline, particularly if homocysteine levels are already elevated.
You only need small amounts of B-12 each day -- 2.4 micrograms for all adults, the Food and Nutrition Board of the Institute of Medicine reports. Some supplements may provide well over 100 percent of this recommendation. But because large doses of B-12 aren't likely to cause any health problems, no toxic dose, or tolerable upper intake level, has been established. This is because once B-12 is freed, as it already is in pills, it has to bind with a specialized glycoprotein called intrinsic factor before it's absorbed. Your body only has a small amount of intrinsic factor, though, limiting the amount of B-12 you can absorb. For example, if you took a 500-microgram pill, you'd probably only absorb about 10 micrograms of it, explains the Office of Dietary Supplements.
- Office of Dietary Supplements: Vitamin B12
- Food and Nutrition Board of the Institute of Medicine: Dietary Reference Intakes (DRIs): Recommended Dietary Allowances and Adequate Intakes, Vitamins
- MedlinePlus: Anemia -- B12 Deficiency
- University of Maryland Medical Center: Vitamin B12 (Cobalamin)
- Proceedings of the National Academy of Sciences of the United States of America: Preventing Alzheimer's Disease-Related Gray Matter Atrophy by B-Vitamin Treatment.