Aching Bones and Tired? Check Vitamin D, B12

Medically reviewed by Dr. William Aung, DocDocDash’s partner doctor network.
Last reviewed: October 2026.

You wake up tired, even after a full night’s sleep. Your bones feel achy, especially in your back, hips, or legs. Your mood has dipped, and you can’t quite explain why. You’ve told yourself it’s stress, or work, or just being busy.

Sometimes it is. But sometimes the cause is much simpler, and much more fixable: your body is running low on a vitamin.

Quick answer: Persistent tiredness, bone or muscle aches, and low mood can be signs of low vitamin D, vitamin B12, or folate. These three deficiencies are common in women, are easy to miss on a routine checkup, and are confirmed with a simple blood test. Once identified, they are usually straightforward to correct.

Aching and tiredness are two of the most common complaints women bring to a doctor, and also two of the easiest to dismiss. They show up with stress, poor sleep, and busy schedules, so they rarely prompt further investigation.

But when they last for weeks or months, they deserve a closer look. Vitamins are the small building blocks your body uses to make energy, build bone, produce red blood cells, and keep your nerves and mood steady. When one runs low, the effects tend to be vague and slow-building, which is exactly why they get overlooked.

How Can Low Vitamin D, B12, and Folate Cause Tiredness, Aches, and Low Mood?

Vitamin D. Vitamin D helps your body absorb calcium and keep bones strong. When levels are low, you may feel deep bone aches, muscle weakness, and fatigue. It also plays a role in mood and immune health. Many people assume deficiency is only a problem in cold, dark countries, but it is common in sunny regions too, especially for people who work indoors, cover up outdoors, or use sun protection consistently.

Vitamin B12. B12 helps your body make healthy red blood cells and keeps your nerves working properly. Low B12 can cause tiredness, weakness, brain fog, low mood, and sometimes tingling or numbness in the hands and feet. It is found mainly in animal foods such as meat, fish, eggs, and dairy, so women who eat little or no animal products have a higher chance of running low. Some digestive conditions and long-term use of certain medications can also reduce absorption.

Folate (vitamin B9). Folate works alongside B12 to make red blood cells and support healthy cell growth. Low levels can cause tiredness, irritability, and low mood. Folate matters especially for women planning a pregnancy, since adequate levels before conception help protect a baby’s early development.

None of these symptoms are unique to one vitamin, and they often overlap. That is why guessing rarely works, and why testing is the clearest way to know.

Who Is Most at Risk of Vitamin Deficiencies?

You are more likely to run low if you:

Spend most of your day indoors or avoid sun exposure
Follow a vegetarian, vegan, or restrictive diet
Have heavy periods, which can affect overall nutrient status
Are pregnant, breastfeeding, or planning a pregnancy
Have a digestive condition that affects how you absorb nutrients
Take certain long-term medications, such as some acid-reducing or diabetes medicines

Being in one of these groups does not mean you are deficient, but it does mean a test is worth considering.

How Do I Test for Vitamin D, B12, and Folate Deficiency?

The good news is that testing is simple. It is a standard blood draw, usually with no special preparation, and results are often back within a few days.

25-hydroxy vitamin D. This measures the vitamin D stored in your body and is the standard test for vitamin D status.
Vitamin B12. Measures the B12 level in your blood. If the result is borderline, your doctor may order an additional marker to confirm.
Folate. Measures your folate level and is often tested alongside B12.
Complete blood count (CBC). Checks your red blood cells, which can show whether low B12, folate, or iron is already affecting them.

One important point: avoid starting high-dose supplements on your own before testing. Taking folate alone, for example, can hide a B12 deficiency, which can allow nerve-related problems to continue unnoticed. A test first, then a supplement plan from a doctor, is the safer order.

If you want everything checked in one visit, DocDocDash can help you find all of these tests in one place.

Frequently Asked Questions

Can low vitamin D really cause bone aches and tiredness?
Yes. Low vitamin D reduces how well your body absorbs calcium, which can lead to bone pain, muscle weakness, and fatigue. A blood test is the only reliable way to confirm it.

How do I know if my tiredness is from low B12 or something else?
You can’t tell from symptoms alone, since B12 deficiency overlaps with iron deficiency, thyroid problems, and stress. A blood test for B12, along with a blood count, helps separate the causes.

How long does it take to feel better once a deficiency is treated?
It varies by vitamin and how low your levels were. Many people begin noticing improvement within a few weeks, while fully restoring levels can take a few months, and a follow-up test confirms progress.

A Simple Rule to Carry Forward

Tiredness and aching that last for weeks are your body asking a question, not giving you a diagnosis. Before assuming it is stress or age, check the basics: vitamin D, B12, and folate.

Ready to take the next step? DocDocDash can help you find hospitals and laboratories offering vitamin and nutrient deficiency testing, and book a consultation if required, all in one place.

Sources: World Health Organization guidance on micronutrient deficiencies; NIH Office of Dietary Supplements fact sheets on vitamin D, vitamin B12, and folate.