Yes. A vitamin B12 deficiency commonly causes tiredness and weakness, because a shortage can lead to megaloblastic anemia, a hallmark of deficiency. B12 is not a general energy booster, though. The NIH says it doesn’t improve energy in people who already get enough, so the real question is whether you are actually low.
How Low B12 Leads to Tiredness
The NIH Office of Dietary Supplements links tiredness and weakness to megaloblastic anemia, a type of anemia that is a hallmark of B12 deficiency. Other possible signs include pale skin, heart palpitations, loss of appetite, numbness or tingling in the hands and feet, balance problems, depression, confusion, memory problems, and a sore mouth or tongue.
Deficiency tends to arrive slowly. Your body keeps a large reserve of B12, so symptoms can take years to appear. That slow build is one reason a deficiency can go unnoticed for a long time.
Who Is Most Likely to Run Low on B12
According to the NIH, several groups face a higher risk:
- Older adults, many of whom make less stomach acid and absorb less B12 from food
- People with absorption problems, including pernicious anemia, atrophic gastritis, celiac disease, Crohn’s disease, or past stomach or intestinal surgery
- Vegetarians and vegans, since only animal foods naturally contain B12
- People who take metformin or acid-reducing medicines such as omeprazole, which can lower B12 levels
If you take any of those medications, our guide to taking supplements with prescription medications is a useful companion.
Getting Tested for B12 Deficiency
Tiredness has many causes, so guessing is not a good plan. Your doctor can test your B12 level to see whether you have a deficiency. If you are low, the cause matters, because the best approach depends on whether the problem is diet, absorption, or a medication. The NIH advises older adults to get most of their B12 from fortified foods or supplements, and your doctor can recommend the right form and dose for your situation.
Do B12 Supplements Boost Energy If You’re Not Deficient?
Marketing often suggests they do. The NIH says otherwise: B12 is frequently promoted for energy, athletic performance, and endurance, but it doesn’t provide those benefits in people who get enough from their diet. If your level is normal, extra B12 is unlikely to be the fix for your tiredness.
That does not make B12 pointless. For someone who is truly deficient, restoring healthy levels is the right goal, and tiredness linked to the deficiency may ease as levels recover under a doctor’s care. The difference is between correcting a real shortage and adding more of something you already have enough of.
Supporting Cellular Energy Beyond B12
When B12 isn’t the answer, it helps to look at how your cells make energy. Performance Lab Energy is a caffeine-free formula with magnesium malate, acetyl L-carnitine, R-lipoic acid, CoQ10, PQQ, and BioPerine, ingredients involved in how mitochondria produce cellular energy.
Frequently Asked Questions
How Long Does It Take to Develop a B12 Deficiency?
It can take years. Your body stores a large reserve of B12, so symptoms often appear slowly.
Can Vegans Get Enough B12?
Only animal foods naturally contain B12, so vegans and vegetarians may need fortified foods or supplements. Ask your doctor what makes sense for you.
Can Medications Lower B12?
Yes. Metformin and acid-reducing medicines such as omeprazole can contribute to low B12 levels, so mention them when you discuss testing.
