Crohn’s Disease and B12
If you’ve had surgery related to Crohn’s disease, an autoimmune disorder of the small intestine, then you may be missing an important component of your digestive system that’s important for B12 absorption, explains EveryDay Health.
The source says the vitamin is absorbed by the terminal ileum at the end of the small intestine, which is a “very common site of Crohn’s disease.” If you can no longer absorb vitamin B12 through pill form supplements, then you’ll need monthly injections, a weekly nasal spray, or even a patch that is relatively new.

Side Effects of Birth Control
Scientific American explains that birth control pills, used by more than 10-million women in the U.S., can deplete your body of certain vitamins, including B12. “And because contraceptives are often taken over extended periods of time, even subtle effects could add up,” adds the source.
According to the source, birth control pills can also rob your system of vitamin B6 and folic acid, as well as vitamin C, magnesium, and zinc, which all play important roles in the human body. Hormone replacement therapy can have the same impacts.

Drinking Away the B12
If you’re taking in large amounts of alcohol, you may be limiting how much B12 gets absorbed into your system. SFGate.com explains that alcohol irritates the mucus lining of the stomach and intestines, and when it does this, your body produces less hydrochloric acid, leading to reduced B12 absorption.
The source explains, “Alcohol not only impairs nutrient absorption by damaging the lining of the gastrointestinal system, but it also prevents nutrients from being fully utilized in the body by altering their transport, storage, and excretion.” Also, when you produce less acid, you can end up with more intestinal bacteria that thrive on B12, which basically means you’ll have more hungry mouths to feed, with less B12 available to actually benefit you.