Can B12 help with Müdigkeit?

Vitamin B12 is essential for red blood cell formation and nervous system function. A deficiency can indeed cause fatigue, weakness, and concentration problems. However, B12 supplementation only helps with fatigue if a genuine deficiency exists. In people with normal B12 levels, taking extra B12 typically does not boost energy – many such products rely more on marketing than solid evidence. Those at highest risk for B12 deficiency include vegans, older adults, and individuals with gastrointestinal conditions (e.g., Crohn's disease, celiac disease) or after gastric surgery. Use of proton pump inhibitors or metformin can also impair absorption. A blood test (holotranscobalamin or total B12 plus homocysteine/methylmalonic acid) is advisable before supplementing. The evidence for B12 in fatigue is strong (human-strong) when deficiency is present, but weak and often marketing-driven for general fatigue without deficiency. Caution: while B12 is considered non-toxic, unnecessary supplementation is a waste of money. Persistent fatigue should always be medically evaluated, as many other causes (iron deficiency, thyroid issues, sleep disorders) are possible.