Feeling exhausted even after a good night’s sleep? Experiencing strange tingling sensations in your hands? These seemingly unrelated symptoms might point to something surprisingly common yet often overlooked. Low or marginal vitamin B12 status without obvious symptoms is much more common, at up to 40% in Western populations, especially in those with low intakes of vitamin B12-rich foods. The tricky part is that B12 deficiency can sneak up on you slowly, mimicking other conditions and leaving you feeling off without knowing why.
Your body needs this essential vitamin for everything from creating healthy red blood cells to keeping your nervous system functioning properly. Here’s the thing though: your body doesn’t make B12 on its own. You have to get it from your diet, and if you’re not absorbing it correctly or eating the right foods, you could be running dangerously low. Let’s explore the warning signs your body might be sending and what you can do about it.
Persistent Fatigue That Won’t Go Away
That’s one of the biggest – and earliest – signs you’re low in B12, as fatigue is one of the first signs of B12 deficiency. Think about it like this: your body relies on the nutrient to make red blood cells, which carry oxygen throughout your body, and when there’s not enough oxygen in your blood, you’ll feel tired no matter how long you sleep. It’s different from regular tiredness. You might sleep well but still wake up feeling drained, like you’re running on empty.
The exhaustion can affect every aspect of daily life. You might struggle to get through your workday or find simple tasks overwhelming. Many people brush this off as stress or aging, delaying proper diagnosis. Still, if fatigue persists alongside other symptoms, it’s worth checking your B12 levels.
Numbness and Tingling in Your Extremities
Shortage of B12 can damage the protective sheath that covers your nerves, leading to some genuinely uncomfortable sensations. Others report a “pins and needles” sensation, and research backs this up. Some people describe it as electricity running through their body, while others feel constant prickling in their fingers and toes.
These pains are all a result of nerve damage, and since vitamin B12 helps your nervous system function properly, they may signal you’re low in the nutrient. The scary part? If left untreated, this nerve damage can become permanent. The good news is that catching it early often means the symptoms can reverse with proper treatment.
Pale or Yellowish Skin
If your complexion starts looking pale or yellow, low B12 may be the culprit, as the vitamin helps with red blood cell production, so when you’re deficient in it, the red blood cells you do have are very fragile and when they break, they release bilirubin – a yellow pigment that makes your skin look jaundiced. It’s kind of ironic, honestly: you’re anemic, so you’d expect to look pale, but the breakdown of fragile cells adds this yellowish tint.
Doctors might initially think of liver problems when they see jaundice. That’s why mentioning other symptoms matters during your checkup. The skin changes aren’t usually the only sign, though they can be one of the more visible ones that prompt people to finally seek medical attention.
Balance Problems and Dizziness
Feeling wobbly or dizzy is another common symptom of B12 deficiency, because being low in the nutrient may lead to nerve damage, causing you to lose your balance, feel less coordinated, or experience vertigo. You might feel unsteady walking or have trouble with tasks requiring coordination. Some people describe feeling like they’re on a boat, even on solid ground.
Patient neurological findings included syncope (n=6), dizziness (n=4), hypotonia (n=9), inability to sit or walk without support, or gait ataxia (n=2). These balance issues increase fall risk, especially concerning for older adults. The neurological impact of B12 deficiency affects multiple body systems simultaneously.
Memory Problems and Brain Fog
The nutrient is crucial for maintaining healthy brain function, and being deficient can cause you to feel confused or forgetful. Maybe you put your keys in weird places or struggle to remember names you’ve known for years. I’ve seen this deficiency mistaken for Alzheimer’s in elderly patients, says one dietitian who’s dealt with countless cases.
Vitamin B12 deficiency is associated with cognitive problems (problems with thinking, judgment, and learning) and memory issues, so it may play a role in conditions such as Alzheimer’s disease and stroke. Recent research published in 2025 suggests that earlier studies defining healthy vitamin B12 levels may have overlooked subtle functional effects of both high and low levels – changes that can affect people even in the absence of obvious symptoms. The cognitive symptoms can be reversible if caught early enough.
Tongue Changes and Loss of Taste
About half of the people with a severe B12 deficiency lose the papillae – or little bumps – on their tongues, especially around the edges, and since most of those papillae contain taste buds, you might lose the ability to taste your favorite foods, too. Your tongue might look unusually smooth and feel sore or inflamed. Some people develop glossitis, where the tongue becomes swollen and red.
Mouth sores can also appear alongside these changes. Food might taste bland or different than usual, which can affect your appetite and nutrition. It’s a vicious cycle: B12 deficiency affects your tongue, which makes eating less enjoyable, potentially worsening nutritional deficits.
Weakness and Muscle Problems
If your muscles aren’t getting enough oxygen from red blood cells, they might feel like mush. You might notice your muscles feeling weaker than usual, or you tire quickly during physical activities you normally handle with ease. The current evidence points to muscle wasting/weakness, myelopathy, neuropathy, and gait disorders as neurological manifestations of B12 deficiency.
The muscle weakness isn’t just about feeling tired. It’s a functional limitation that affects your ability to perform daily tasks. Climbing stairs, carrying groceries, or even standing for extended periods becomes challenging. Interestingly, this symptom often improves relatively quickly once B12 levels are restored.
Vision Changes
Visual pathways are very vulnerable to vitamin B12 deficiency, and the visual evoked potential is often found prolonged in patients with vitamin B12 deficiency neurological syndrome even if they are otherwise asymptomatic. A rare condition from a lack of vitamin B12 is optic neuropathy, which means that the optic nerve, the nerve that transmits visual information from the eye to the brain, is damaged, and this can cause a gradual loss of vision and result in blind spots, though less than 1% of people with B12 deficiency report getting optic neuropathy.
You might experience blurred vision or difficulty seeing clearly. The vision problems usually develop gradually rather than suddenly. While this symptom is less common than others, it’s serious enough to warrant immediate medical attention if you experience vision changes along with other B12 deficiency symptoms.
Mood Changes and Depression
Having low levels of B12 can cause elevated levels of a sulfur-containing amino acid called homocysteine, which may contribute to the development of depression by increasing oxidative stress, DNA damage, and cell death in the body. You might feel irritable, anxious, or depressed without understanding why. The psychiatric disorders linked to vitamin B12 deficiency range from behavioral disturbances and cognition problems to dementia.
The connection between B12 and mental health is complex. SAM influences serotonin, norepinephrine, and dopamine synthesis, suggesting that, in addition to structural consequences of vitamin B12 deficiency, functional effects on neurotransmitter synthesis that may be relevant to mental status changes may occur. Treating the deficiency often helps improve mood, though it’s not a magic cure for all mental health issues.
What to Eat to Boost Your B12
Fish and red meat are excellent sources of vitamin B12, and poultry and eggs also contain vitamin B12. A 3.5-ounce (100-gram) serving of lamb liver provides an incredible 3,571% of the Daily Value (DV) for vitamin B12, though organ meats aren’t everyone’s favorite. Shellfish lovers can rejoice in meeting over 700% of their daily value of vitamin B12 with just 3 ounces of cooked clams.
For vegetarians and vegans, the situation is trickier. A survey of naturally occurring and high Vitamin B12-containing plant-derived food sources showed that nori, which is formed into a sheet and dried, is the most suitable Vitamin B12 source for vegetarians presently available, as consumption of approximately 4 g of dried purple laver (Vitamin B12 content: 77.6 μg /100 g dry weight) supplies the RDA of 2.4 μg/day. Fortified cereals, nutritional yeast, and plant-based milks with added B12 are also good options. Fun fact: Eating full-fat plain yogurt has been shown to improve vitamin B12 deficiency because the vitamin is more easily absorbed in dairy products.
Honestly, if you’re experiencing several of these symptoms, the smartest move is getting your blood tested rather than just changing your diet. Adults need around 2.4 micrograms (mcg) of vitamin B12 a day, which sounds like a tiny amount, yet so many people fall short. At least 4% of people between 40 and 59 are lacking in the nutrient, and even more are borderline. The prevalence increases with age, making awareness even more critical.
The body is pretty remarkable at signaling when something’s wrong. Those weird sensations, that persistent exhaustion, the brain fog – they’re not just normal parts of aging or stress. They might be your body’s way of saying it needs more B12. What makes B12 deficiency particularly sneaky is how slowly it develops and how varied the symptoms can be. Someone might have primarily neurological symptoms while another person mainly experiences fatigue and mood changes.
Getting diagnosed early makes all the difference. All patients with neurological symptoms of vitamin B12 deficiency recovered within one month after vitamin B12 supplementation in one study, showing just how responsive the body can be to treatment. Did you know B12 deficiency could cause so many different symptoms? Share your thoughts below.