The Best Way to Take Vitamin B12 Supplements

Vitamin B12 is essential to healthy red blood cell formation and proper neurological functioning, but a lot of people who are deficient go undiagnosed. Your doctor can help you determine if you are in need of a supplement to bring you up to healthy levels. Vitamin B12 is prevalent in foods, but you can also get it through supplements that come in various forms, including injectable, sublingual and oral. The type that's best for you depends on the reason for your deficiency and your preferences.

Vitamin B12 deficiency may affect as much as two-fifths of the population, suggested the Framingham Offspring Study published in 2000. Symptoms of deficiency include fatigue, tingling arms and legs, brain fog, loss of appetite and diarrhea. Vegans and vegetarians are at particular risk of deficiency because B12 naturally occurs only in animal-derived foods, such as meat, eggs and dairy. People with chronic digestive problems, such as Crohn's disease and celiac disease; alcoholics; those who've undergone weight-loss surgery; chronic poppers of antacid pills; and sufferers of pernicious anemia are also at risk.

Oral supplementation is easy, but isn't always effectively absorbed by your system. The Office of Dietary Supplements, a branch of the National Institutes of Health, notes that even the most healthy people can absorb only about 10 micrograms of a 500-microgram oral supplement. This might be adequate for the average adult, who requires just 2.4 micrograms daily, and isn't showing signs of serious deficiency. A 2003 issue of the "British Journal of Clinical Pharmacology" determined that a 500-microgram dose of vitamin B12 given sublingually -- dissolved under the tongue -- was effective in treating deficiencies.

People with pernicious anemia, a condition in which you do not properly absorb vitamin B12 through the digestive tract, may not find their condition improves with oral supplementation. Older adults who fail to produce optimal amounts of stomach acid and people who have other malabsorption issues also have trouble absorbing oral vitamin B12. In these cases, vitamin B12 injections are often recommended because they bypass the digestive tract. High oral doses of vitamin B12 that involve 1,000 to 2,000 micrograms daily may also be as effective as injections in some cases, though, according to a study published in the Cochrane Database of Systematic Reviews in July 2005. Your doctor will help you decide whether a high-dose oral option is right for you.

Nasal administration of vitamin B12 is a possible alternative to oral dosing or injections. It comes in a gel that you apply inside your nostrils. The Office of Dietary Supplements notes that, although this form seems to effectively raise vitamin B12 levels, it hasn't been thoroughly vetted in a scientific setting. Because it's less proven than oral and injectable methods, intranasal vitamin B12 is usually prescribed only to those whose levels have been restored to normal with injections and who are considered to be in remission.