The causes of vitamin B12 deficiency vary, with diet being a leading factor—especially for vegetarians and vegans who may lack natural sources. Other contributing conditions include gastritis, pernicious anemia, Crohn’s disease, celiac disease, and the aftereffects of gastrointestinal surgery. Excessive alcohol use and certain genetic conditions can also impair absorption. To prevent deficiency, it’s important to consume foods rich in B12 such as liver, shellfish, fish like salmon and tuna, dairy products, eggs, and fortified cereals. Regular intake of these foods supports overall health and helps maintain the body’s B12 levels.