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Have you ever been told your blood work is “normal,” yet you still feel exhausted, foggy or just not like yourself? I see this all the time. As a pharmacist, one of the most overlooked nutrient issues

I encounter is vitamin B12 deficiency, especially in people whose lab results technically fall within the “normal” range.

The problem is that laboratory reference ranges are wide. What’s considered normal on paper may not be optimal for your brain, nerves or energy levels. In other words, you can be “low-normal” and still feel pretty terrible.

Vitamin B12 is essential for red blood cell formation, nerve health, DNA synthesis and even mood regulation. When levels dip, your body often whispers before the deficiency shows up definitively on your labs.

Early symptoms of deficiency

One of the most common clues is fatigue that doesn’t improve with rest. This isn’t just being tired; it’s that dragging, heavy exhaustion that makes even simple tasks feel harder. Because B12 helps carry oxygen through your bloodstream, low levels can leave your tissues under-fueled.

Then there’s brain fog. I once had a friend call me about his wife, who had been placed in a nursing facility with suspected early dementia. I suggested checking her B12. She was deficient.

After replenishment, her mind became clear again, and she went home! That case has stayed with me because it’s a reminder: Sometimes what looks like a neurological disease is simply a nutrient deficiency.

Tingling or numbness in your hands and feet is another classic sign that occurs early on (before your labs prove a deficiency). That’s because B12 supports the protective coating around your nerves called the myelin. When that’s compromised, signals don’t travel properly. Some people describe it as pins and needles or even a burning sensation.

Mood changes can also show up quietly. B12 plays a role in the biochemical pathways that regulate neurotransmitters like serotonin and dopamine. When levels drop, you might feel more anxious, irritable or just “flat.” It’s subtle but very real.

Even your appearance can shift. B12 deficiency can lead to a pale complexion, sometimes with a faint yellowish tone.

And then there’s digestion. B12 absorption depends on stomach acid and a protein called intrinsic factor. Your ability to absorb B12 can decline if you take certain medications — what I call drug muggers. Metformin is just one of many meds that deplete B12.

Take a B complex

Here’s something else people don’t realize: Taking B12 alone isn’t always the best solution. The B vitamins work as a team. When you take one in isolation long-term, you can create imbalances. That’s why a well-formulated B complex is often a smarter approach.

Sometimes the body whispers before it shouts. And when it comes to B12, those whispers are worth listening to.

If this sounds like you, don’t stop here. I cover testing, medications that deplete B12 and smart supplement strategies on my website. Head to suzycohen.com and sign up for my free newsletter for practical tips you can use right away.

This information is opinion only. It is not intended to treat, cure or diagnose your condition. Consult with your doctor before using any new drug or supplement.

Suzy Cohen is a registered pharmacist and author of The 24-Hour Pharmacist and Real Solutions from Head to Toe.