B12 deficiency symptoms, and how testing works

B12 deficiency symptoms are easy to miss because they overlap with ordinary tiredness and stress, and they usually develop gradually. Your body uses vitamin B12 to make red blood cells and to keep nerves working normally, so running low can show up as tiredness, changes in mood or memory, or odd sensations in your hands and feet.

Adults need only about 2.4 micrograms of B12 a day, according to Health Canada. For many people, the problem is absorbing it rather than eating enough. Here is what to watch for, who is more likely to run low, how testing works, and when to see a doctor promptly.

B12 deficiency symptoms to watch for

Symptoms come from two directions: anemia (too few healthy red blood cells) and effects on the nerves and brain. You may notice:

• tiredness, weakness and low energy
• shortness of breath, a pounding heart or headaches
• loss of appetite, indigestion or diarrhea
• a sore, red tongue, sometimes with mouth sores
• pins and needles or numbness, often in the hands and feet
• muscle weakness, or problems with balance and coordination
• problems with memory, understanding or judgment, and changes in mood
• changes in your vision

Nerve symptoms can appear even when there is no anemia, so a normal blood count doesn’t rule out low B12. The NHS notes that the longer a deficiency goes unaddressed, the higher the chance that some nerve damage becomes permanent. Numbness, tingling or balance changes deserve prompt attention rather than a wait-and-see approach.

Who is at risk of low B12?

B12 comes mostly from animal foods, such as meat, fish, eggs and milk, and from fortified foods such as some breakfast cereals. Your body needs stomach acid to break the B12 off the food protein, then a different protein called intrinsic factor to keep it safe from the stomach acid, and then only one part of the intestines actually absorbs it, so anything that interferes with that chain raises your risk:

• Being an older adult. Many older adults make less stomach acid, which makes it harder to release B12 from food.
• Vegan eating without a B12 supplement or fortified foods. Babies breastfed by a vegan mother who doesn’t take B12 are also at risk.
• Low intrinsic factor. Some people don’t make as much as others.
• Stomach or bowel surgery, including bariatric surgery, especially if part of the stomach or small intestine was removed.
• Crohn’s disease or celiac disease.
• Long-term metformin or acid-reducing medicines such as proton pump inhibitors.

Because the body stores B12, mainly in the liver, a deficiency from diet alone can take years to develop. If you’re in a risk group but feel well, you may not need a test at all: British Columbia’s clinical guideline says routine B12 testing in people without symptoms isn’t supported by evidence, and suggests considering a supplement for people with risk factors instead.

Practical steps if you’re in a risk group

• If you eat little or no animal food, include a B12 supplement or B12-fortified foods every day, not just now and then.
• If you take metformin or an acid reducer long term, ask your prescriber whether B12 checks or a supplement make sense for you.
• If you’re an older adult, or have had stomach or bowel surgery, mention it when you discuss tiredness, tingling or memory changes with any practitioner.

How is B12 deficiency diagnosed?

A blood test measures your B12 level. It is usually read alongside a complete blood count, which can show anemia or unusually large red blood cells, a common clue to low B12. Folate, another B vitamin, is sometimes checked too, because low folate can cause a similar type of anemia.

Results aren’t always clear-cut. B.C.’s guideline describes a large grey zone between normal and low levels, and labs don’t all agree on cut-offs. Your practitioner may repeat the test or add others if the picture is unclear.

Before and after your test

• Bring a list of every supplement and medication you take, including multivitamins and B-complex products.
• Ask whether anything else on the requisition needs you to fast beforehand.
• If you start B12 treatment, B.C.’s guideline suggests waiting at least two months before repeating the test.
• Ask for a copy of your results so you can share them with your family doctor.

Questions to ask about your B12 results

• What was my level, and what is this lab’s reference range?
• Is my result clearly low, clearly normal, or in the grey zone?
• Did my complete blood count show anemia or large red blood cells?
• If my B12 is low, what might be causing it, and does that cause need its own tests?
• When should the test be repeated, and who will follow up with me?

How is low B12 treated?

Treatment depends on the cause and on how low your level is. B12 can be taken by mouth or given by injection, and the route, dose and schedule are decided with your health care provider. Finding the cause matters as much as the number, because low B12 can point to an absorption problem, a medication effect or a gap in your diet. Naturopathic doctors sometimes aim for a higher range than the labs would suggest is normal.

If you’ve been prescribed B12 in any form, don’t stop or change it without talking to whoever prescribed it. Keep your family doctor informed, especially if you have nerve symptoms or take metformin or acid reducers.

Seeing a naturopathic doctor at Natura

At Natura Integrative Care Clinic in Steinbach, a first naturopathic visit is 60 to 90 minutes. Some first visits are booked as an accelerated two-part visit: up to 60 minutes with a registered nurse, who completes your intake, including your health history and vital signs, and then 30 minutes with the naturopathic doctor. Your ND goes through your symptoms, diet, medications and history, may do a physical exam, and may order testing. You then discuss a plan together.

Lab testing ordered by a naturopathic doctor isn’t covered by Manitoba Health, so you pay the lab directly. Prices vary widely depending on what’s tested, but generally start around $75. Our guide to lab testing with a naturopathic doctor in Manitoba explains how it works. Dr. Erin Esau, ND sees patients in person in Steinbach, and visits can also be booked by secure video. If tiredness is your main concern, see why am I always tired?