Anemia, Iron & Blood Health
B12 and Folate Deficiency Anemia in Women: Symptoms, Causes and Tests
B12 and folate deficiency anemia happens when you don't have enough vitamin B12 or folate to make healthy red blood cells. Both cause anemia with unusually large red cells (macrocytic or megaloblastic anemia). B12 deficiency can also damage nerves, sometimes before your blood count even changes, so tingling hands and feet deserve a real workup, not a shrug.
How it usually shows up
Most people don't walk in saying "I think I'm low on B12." They say they're exhausted, foggy, or that their feet feel strange. The tiredness creeps up over months, and it's easy to blame on work, kids or bad sleep.
Here's what clinicians commonly hear.
Anemia symptoms (both deficiencies):
- Tiredness and weakness
- Shortness of breath on stairs or subway steps
- Pale or slightly yellow skin
- Fast heartbeat
- Dizziness
- A sore, red or oddly smooth tongue
- Mouth sores
Extra symptoms of B12 deficiency:
- Numbness or tingling in hands and feet ("pins and needles" that don't go away)
- Trouble with balance or walking
- Memory problems, confusion or brain fog
- Depression or irritability
- Vision changes, in more severe cases
Nerve damage from B12 deficiency can become permanent if it isn't treated. That's the main reason not to wait.
Why these two vitamins matter for your blood
Your bone marrow needs B12 and folate to copy DNA when it makes new red cells. Without enough of either, the cells grow larger but don't divide properly. These big, immature cells work poorly and die early, and you end up anemic.
B12 also keeps your nerves and brain working, which is why it can cause neurological symptoms that folate deficiency doesn't.
Who's at risk for low B12?
| Cause | Why it happens |
|---|---|
| Pernicious anemia | An autoimmune condition that blocks B12 absorption in the stomach |
| Vegan or strict vegetarian diet | B12 is found naturally in animal foods |
| Weight-loss surgery | Changes to the stomach and intestine reduce absorption; see anemia after bariatric surgery |
| Long-term metformin | Can lower B12 levels over time |
| Long-term acid-reducing medicines | Stomach acid helps release B12 from food |
| Celiac disease or Crohn's disease | Gut damage reduces absorption |
| Older age | Less stomach acid |
If you take metformin or a daily heartburn medicine and you've never had B12 checked, that's worth bringing up at your next visit. Many people have been on these for years without anyone mentioning it.
Who's at risk for low folate?
- Diets low in leafy greens, beans and fortified grains
- Pregnancy and breastfeeding, which raise folate needs
- Heavy alcohol use
- Celiac disease and other absorption problems
- Some medicines, such as certain anti-seizure drugs and methotrexate
- Conditions that speed red cell turnover, such as sickle cell disease
In the U.S., many grain products are fortified with folic acid, which has made severe folate deficiency less common.
B12, folate and pregnancy
Folic acid before you're pregnant
The CDC recommends that everyone who could become pregnant get 400 micrograms of folic acid daily, starting at least a month before pregnancy. Folic acid helps prevent neural tube defects such as spina bifida, which form in the first weeks, often before you know you're pregnant. Most prenatal vitamins already contain it, so if you're even thinking about pregnancy, starting one now is an easy step.
Some people need more, such as anyone who's had a previous pregnancy affected by a neural tube defect. Your clinician will tell you the right amount.
B12 in pregnancy
Low B12 in pregnancy has been linked to concerns for the baby's development. Babies of mothers with low B12, especially exclusively breastfed babies of vegan mothers, can develop deficiency themselves. If you're vegan or have had bariatric surgery, ask about a B12 check before or early in pregnancy.
What the testing involves
It's a regular blood draw, no fasting needed for most of these unless your clinician says otherwise. Your clinician may order:
- Complete blood count (CBC), which often shows large red cells (a high MCV)
- Vitamin B12 level
- Folate level
- Methylmalonic acid (MMA) and homocysteine, which help confirm deficiency when B12 is borderline
- Intrinsic factor antibodies, to check for pernicious anemia
One thing that trips people up: you can have iron deficiency and B12 or folate deficiency at the same time. Iron deficiency makes red cells small; B12 and folate deficiency make them large. Together they can cancel out, so your red cell size looks normal on the CBC. That's why a full workup matters. See iron deficiency anemia in women.
How it's treated
It depends on the cause:
- B12 deficiency may be treated with B12 shots or high-dose B12 by mouth. People with pernicious anemia, and many people after certain bariatric surgeries, need treatment for life.
- Folate deficiency is treated with folic acid plus diet changes.
Your clinician decides the form, dose and how long. A common question is whether pills work as well as shots. For many people they do, but if your body can't absorb B12 from the gut (as with pernicious anemia), your clinician may recommend injections. Ask which fits your cause.
Don't treat suspected B12 deficiency with folic acid alone. It can improve your blood count while nerve damage keeps going.
Food sources:
- B12: meat, fish, eggs, dairy, fortified cereals and plant milks, nutritional yeast
- Folate: leafy greens, beans, lentils, asparagus, citrus, fortified grains
Can you take too much?
According to the NIH, vitamin B12 has a low potential for toxicity, and no upper limit has been set. Taking folic acid above the recommended amount without a clinician's advice isn't recommended, because it can hide B12 deficiency. Test first, then follow your clinician's plan.
Questions to bring to your appointment
- Were my B12 and folate checked, or just my blood count?
- Is my red cell size (MCV) high, normal or low?
- Could I have more than one deficiency, like iron and B12 together?
- What's causing this? Do I need tests for pernicious anemia or celiac disease?
- Should I take B12 by mouth or by injection, and for how long?
- Could any of my medicines be lowering my B12?
- If I'm planning a pregnancy, how much folic acid should I take?
Bring a list of everything you take, including supplements. Some affect B12 or folate levels, and some can interfere with lab tests.
When to see a doctor
Make an appointment if you:
- Feel tired, weak or short of breath for weeks
- Notice numbness, tingling or balance problems
- Follow a vegan diet and haven't been tested
- Have had bariatric surgery
- Take metformin or acid-reducing medicine long-term
- Are planning a pregnancy
An OB/GYN or women's health nurse practitioner can order testing and review folic acid before pregnancy. Browse women's health nurse practitioners in Queens or search for a provider near you.
Seeing a hematologist in New York
Most B12 and folate deficiency is handled by primary care or OB/GYN clinicians. A hematologist can help if the cause isn't clear, your counts don't respond to treatment, or more than one type of anemia is in the picture. Premier Hematology & Oncology, which sponsors our professional resources, offers hematology consults at centers across NYC, Long Island and the Hudson Valley. Clinicians can find referral details on our hematology partners page.
Frequently asked questions
What are the symptoms of B12 deficiency in women?
Common symptoms include fatigue, weakness, pale skin, a sore or smooth tongue, numbness or tingling in the hands and feet, balance problems, memory trouble and mood changes.
What is the difference between B12 and folate deficiency?
Both cause anemia with large red blood cells. B12 deficiency can also damage nerves, which folate deficiency does not. Taking folic acid alone can improve the anemia of B12 deficiency while nerve damage continues, so both should be checked.
Why is folic acid important before pregnancy?
Folic acid helps prevent neural tube defects, serious birth defects of the brain and spine that form very early in pregnancy. The CDC recommends that everyone who could become pregnant get 400 micrograms of folic acid daily.
Can vegans get enough B12?
B12 is found naturally in animal foods, so vegans usually need fortified foods or a supplement. Ask your clinician about testing and the right source for you.
Sources
- NIH Office of Dietary Supplements — Vitamin B12 Fact Sheet for Consumers
- NIH Office of Dietary Supplements — Folate Fact Sheet for Consumers
- CDC — Folic Acid: Recommendations
- USPSTF — Folic Acid Supplementation to Prevent Neural Tube Defects (2023)
- NHLBI — Vitamin B12-Deficiency Anemia
This article is for general education and is not medical advice. It does not replace an evaluation by a licensed clinician who knows your history. If you think you have a medical emergency, call 911.