If you've been feeling inexplicably tired, foggy, or have noticed odd tingling in your hands or feet, vitamin B12 deficiency nutrition is one of the first things I think about as a dietitian — and one of the most under-recognised issues I see in clinic. B12 deficiency is common, often develops slowly and quietly, and is genuinely fixable once identified. But it's frequently missed because the symptoms overlap with so many other things: stress, iron deficiency, thyroid issues, or simply "being busy."
I work with clients across the Netherlands, Belgium, Germany and Turkey, and B12 is a topic I discuss constantly — with vegans and vegetarians, with older adults, with people managing type 2 diabetes on metformin, and with anyone who's had digestive or gastric surgery. This article walks through who's actually at risk, what the symptoms look like, which foods provide B12, and when food alone genuinely isn't enough.
One important note before we go further: nutrition can meaningfully improve and, in food-related cases, resolve a B12 deficiency, but it works alongside your doctor, not instead of them. B12 status should always be confirmed with a blood test, and if levels are significantly low or your deficiency has a medical cause, your GP may prescribe oral supplements or injections. Please don't self-diagnose or self-treat a suspected deficiency without testing first — some symptoms of low B12 overlap with other conditions that need their own specific care.
Why Vitamin B12 Matters So Much
B12 (cobalamin) is essential for producing healthy red blood cells, maintaining the protective coating around your nerves, and supporting DNA synthesis. Unlike many vitamins, your body can store several years' worth of B12 in the liver, which is actually part of why deficiency can sneak up on people — by the time levels and symptoms become noticeable, the depletion has often been building for a long time.
Who Is Actually at Risk of B12 Deficiency
B12 deficiency isn't random — it clusters around a few identifiable groups, and knowing whether you fall into one of them is genuinely useful:
- Vegans and vegetarians. B12 is naturally found almost exclusively in animal-derived foods, so anyone eating a fully plant-based diet, and many vegetarians, need a reliable fortified or supplemental source.
- Older adults. As we age, stomach acid production naturally declines, and B12 needs acid to be released from food and absorbed properly. This means older adults can be B12 deficient even while eating plenty of animal products.
- People on metformin. This very common diabetes medication is well documented to reduce B12 absorption over long-term use. If you've been on metformin for years, ask your doctor about periodic B12 testing.
- People taking long-term acid reducers. Proton pump inhibitors (like omeprazole) and H2 blockers reduce stomach acid, which — as above — is needed to free B12 from food proteins.
- Anyone who has had gastric or bowel surgery. Gastric bypass, sleeve gastrectomy, or resections of the small intestine (particularly the ileum, where B12 is absorbed) significantly raise deficiency risk, sometimes permanently, regardless of diet.
- People with autoimmune conditions affecting the stomach, such as pernicious anaemia, where the body can't produce the "intrinsic factor" protein needed to absorb B12 at all — this group typically needs injections regardless of diet.
- People with coeliac disease or Crohn's disease, where intestinal damage can impair absorption.
If more than one of these applies to you, it's worth flagging to your GP specifically and asking for a B12 blood test rather than waiting for symptoms to appear.
Recognising the Symptoms
B12 deficiency symptoms can be subtle at first and easy to dismiss. Common signs include:
- Persistent fatigue or low energy that doesn't improve with rest
- Pins-and-needles or tingling sensations in the hands or feet (a sign the nerves are being affected)
- Brain fog, poor concentration, or memory issues
- Mood changes, including low mood or irritability
- Pale or slightly yellow-tinged skin
- A sore, red, or unusually smooth tongue
- Mouth ulcers
- Breathlessness or heart palpitations with mild exertion
- In more advanced cases: balance problems or unsteady walking
I want to be clear that none of these symptoms are unique to B12 deficiency — they overlap heavily with iron deficiency, thyroid problems, and other conditions. That overlap is exactly why testing matters more than guessing.
Food Sources of Vitamin B12
For people who eat animal products, getting enough B12 from food is usually straightforward. Good sources include:
- Organ meats (liver is exceptionally rich in B12)
- Beef, lamb, and other red meats
- Fish and shellfish, particularly clams, mussels, sardines, salmon, and trout
- Eggs
- Dairy products — milk, yoghurt, cheese
For anyone eating plant-based or mostly plant-based, reliable sources are more limited and typically need to be deliberately sought out:
- Fortified plant milks (soy, oat, almond) — check the label, as fortification levels vary by brand
- Fortified breakfast cereals
- Nutritional yeast that's specifically fortified with B12 (not all brands are — check the packaging)
- Fortified plant-based meat alternatives, again depending on the brand
I want to be honest here: for a fully vegan diet, relying on fortified foods alone to consistently hit adequate B12 intake is difficult in practice, because you'd need to eat several fortified portions daily, every day, without fail. This is one of the few areas where I genuinely recommend most vegans take a B12 supplement rather than relying on food alone — it isn't a failure of your diet, it's simply the reality of where B12 comes from in nature (it's produced by bacteria, and animals accumulate it through their diet or gut flora).
When Food Isn't Enough: Supplements and Injections
This is where I always bring the conversation back to your doctor. Whether food, oral supplements, or injections are the right approach depends on why your B12 is low:
- If your diet is the main driver (e.g. a vegan diet without fortified foods or a supplement), oral B12 supplements are usually effective and well absorbed.
- If your deficiency is due to an absorption problem — pernicious anaemia, gastric surgery, long-term acid reducers, or advanced age with low stomach acid — oral supplements may not be reliably absorbed, and B12 injections (administered by a doctor or nurse) are often needed instead, sometimes for life.
- If you're on metformin long-term, your doctor may recommend either monitoring levels periodically or a modest daily oral supplement as a preventive measure.
The blood test matters because treatment really does differ based on cause, and taking high-dose oral supplements when you actually have an absorption problem may not correct the deficiency at all, giving you false reassurance while symptoms continue.
Common Myths About B12
"If I feel fine, my B12 must be fine." Not necessarily — because your liver stores years' worth of B12, symptoms often only appear once stores are significantly depleted. Risk factors matter more than how you currently feel.
"I eat meat, so I definitely don't need to worry about B12." Eating animal products doesn't guarantee absorption. Age, medications, and gut health all affect how much of the B12 you eat actually gets absorbed.
"B12 injections are only for vegans." Actually the opposite is often true — injections are most commonly needed for people with absorption problems (pernicious anaemia, post-surgery, long-term acid reducer use), regardless of how much B12 is in their diet.
"More B12 is always better." B12 is water-soluble and considered to have a good safety margin, so it's not typically dangerous in higher doses, but taking large amounts doesn't confer extra benefit if your levels are already adequate. Testing first avoids unnecessary supplementation and wasted money.
"Energy drinks and B12 shots at the gym will fix my fatigue." If your fatigue isn't actually caused by low B12, extra B12 won't fix it. Getting tested tells you whether B12 is actually your issue, rather than guessing.
Practical Steps If You Suspect a Deficiency
- Ask your GP for a B12 blood test — this is usually a simple, inexpensive addition to routine bloodwork, and sometimes it's worth also checking folate and iron at the same time, since deficiencies can overlap.
- If you're vegan or vegetarian, don't wait for symptoms — build a fortified food habit or a daily/weekly supplement into your routine proactively.
- If you're on metformin or long-term acid reducers, mention this to your doctor and ask whether periodic B12 checks make sense for you.
- If levels come back low, work with your doctor on the right form of treatment (oral vs injection) based on the likely cause.
- Recheck levels after starting treatment to confirm they're actually improving, not just assume the supplement is working.
Working With Hanzi Nutrition
B12 deficiency is one of those areas where a small, well-targeted change to your diet or supplement routine can make a genuinely noticeable difference to how you feel — but getting there requires understanding your personal risk factors, not following generic advice. I love working through this with clients: whether you're vegan and want a realistic, sustainable way to cover your B12 needs, older and want to know what to watch for, or navigating a new diagnosis like coeliac disease or a gastric procedure that's changed how your body absorbs nutrients.
When you work with me, we start with a thorough first consultation covering your health history, medications, diet pattern, and any bloodwork you already have. From there, I build a personalised nutrition plan — realistic food sources, appropriate supplementation where food genuinely can't cover your needs, and a clear plan for what to ask your GP to test. I then provide ongoing support as we track how you're feeling and adjust as new bloodwork comes in, always coordinating with your doctor so we're working from the same information, not guessing in parallel.
I work fully online, in English and Turkish, with clients across the Netherlands, Belgium, Germany and Turkey.
If you're tired, foggy, or simply unsure whether your diet is covering your B12 needs, book a consultation with me and let's figure out what's actually going on.
Hanzi Nutrition offers dietitian-led nutrition counselling across the Netherlands, Belgium, Germany, and Turkey, fully online, in English and Turkish. This article is general education and not a substitute for individual medical care. Please coordinate any changes to your nutrition, supplements, or treatment with your doctor.
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