The Best Way to Absorb B12

The symptoms of a vitamin B12 deficiency range from mild to debilitating. Taking a vitamin B12 supplement should help if you're deficient in this nutrient. Another option is to get vitamin B12 shots, but there are some risks you should be aware of.

In developed countries like the United States, vitamin and mineral deficiencies are becoming increasingly rare. There are many food products, ranging from fruit juice to cereals, that are fortified with nutrients. This is important because some people can't get all their nutrients through diet alone.

Vegetarians and vegans, for example, can have trouble fulfilling their nutrient requirements because some vitamins, such as B12, come mostly from animal products. To solve this problem, fortified vitamin B12 foods, such as breakfast cereals, were developed. One serving of fortified nutritional yeast, for example, provides 100 percent of the daily recommended vitamin B12 intake, according to the National Institutes of Health (NIH).

If you're careful about your diet, it's possible to meet your daily requirements for vitamin B12. For adult men and women, the recommended daily amount is 2.4 micrograms, points out the NIH. Pregnant and lactating women need slightly higher amounts.

​Read more:​ Why Your Body Needs Vitamin B12 — and How to Get More

To put that into perspective, you can drink two cups of milk or eat a 3-ounce serving of canned tuna to meet your daily requirements. That's why only 1.5 to 15 percent of the population is deficient in vitamin B12, reports the NIH. It's relatively easy to get enough of this nutrient as long as you choose the right foods.

If your diet isn't varied enough to include foods rich in vitamin B12, you may develop a deficiency. Its symptoms may include anemia, weakness and loss of balance. These issues can range from mild to severe, so you might be deficient in vitamin B12 without realizing it.

People specifically at risk for a deficiency are those over age 50, vegans and individuals who've had weight loss surgery. Those with celiac or Crohn's disease may become deficient in this nutrient too. You can ask your doctor for a blood test to check your vitamin B12 levels.

If you find out that you're deficient in this nutrient, there are two possible causes. The first is that you simply aren't getting enough vitamin B12 in your diet. Or you may have trouble absorbing vitamin B12 from food and supplements. While dietary supplements may help, they're unlikely to improve your body's ability to absorb this vitamin.

The pepsin and acid in your stomach help release vitamin B12 from ingested proteins, according to Colorado State University. Then this nutrient goes from your digestive system to the small intestine. There it's picked up by something called intrinsic factor, which binds to it and allows it to be transported into the bloodstream.

Damage to the small intestine can interfere with your ability to absorb vitamin B12. Some types of surgery, such as small bowel resection, may further affect nutrient absorption into your system and increase the risk of vitamin and mineral deficiencies.

​Read more:​ The Side Effects of Too Much Vitamin B12

In either case, your deficiency can usually be remedied by a high-dose vitamin B12 supplement taken either orally or through intramuscular injection. Oral supplements are roughly as effective as injections, points out the American Academy of Family Physicians (AAFP).

Injections are commonly used, but they carry potential risks, such as localized pain and swelling. According to the AAFP, the dosage used for oral supplementation would be 1,000 to 2,000 micrograms per day for the first one to two weeks of treatment. After that period, a maintenance dose of 1,000 micrograms per day for life may be required.

If vitamin B12 injections are used, you'll get 100 to 1,000 micrograms every day or every other day for one to two weeks. Once the treatment ends, your doctor may administer a 100- to 1,000-microgram injection every one to three months.

The doctor will work with you to make sure that the treatment is effective and adjust the dosing. By using supplements and changing your diet, you can most likely compensate for a lack of vitamin B12 even if your body has trouble absorbing it.