Vitamin B12 deficiency can cause symptoms like headaches, fatigue, depressive mood, gastrointestinal issues, and more. While vegetarians are at a higher risk of vitamin B12 deficiency, it can affect non vegetarians too. Check B12 Injections: What's the Buzz? Vitamin B12 is the star of several essential functions in the body. However, it's common to be deficient in B12 and as a consequence experience fatigue, Benefits of B12 Injections for Optimal Health Experiencing any of these symptoms? B12 supplementation might be right for you. Some causes of low B12 are diet, alcohol use, certain diseases like Chrohn's and Celiac Disease, and Gastric Bypass surgery, B12 Headache: The Link Between Vitamin B12 and Headaches