If you're constantly battling fatigue, brain fog, or tingling sensations, only for a Vitamin B12 test to return as 'normal,' you are not losing your mind. A medical expert has stepped forward to explain this frustrating phenomenon, revealing that a condition known as 'functional B12 deficiency' could be the hidden culprit.
The Illusionist of Modern Medicine
Dr Anshuman Kaushal, a surgeon from Apollo Delhi, has shed light on this often-missed diagnosis. He explains that the problem isn't always the amount of B12 in your blood, but how effectively your body can use it. Most standard laboratory tests only measure total serum B12, failing to assess the active form that your cells desperately need.
"Normal B12 but still exhausted? You’re not crazy, your cells are starving," Dr Kaushal, known on social media as theangry_doctor, stated. He described functional B12 deficiency as the "award-winning illusionist of modern medicine," where perfect lab results mask a state of cellular bankruptcy.
Why Your Cells Could Be Starving
The doctor elaborated that a significant portion of the B12 circulating in your bloodstream is bound to an inactive carrier protein. This renders it useless, as it cannot enter cells to perform its vital functions. It's akin to having a full bank account but no ATM card – you look rich on paper, but you feel broke.
This deficiency can manifest in a string of debilitating symptoms, including:
- Extreme tiredness and fatigue
- Brain fog, poor concentration, and forgetfulness
- Feelings of depression and low mood
- Nerve issues such as pins and needles or tingling in the hands
Failure to correctly identify and treat this issue can, over time, lead to permanent nerve and brain damage.
The Solution: What Tests to Request
For those who continue to suffer symptoms despite normal B12 readings, Dr Kaushal advises a different approach. He recommends requesting specific tests that measure levels of methylmalonic acid (MMA) and homocysteine in the blood. These markers provide a much clearer picture of whether your body is actually utilising B12 effectively.
"Your B12 levels might look ‘normal’ on paper… but your cells may still be starving," he warned. "Brain fog, fatigue, tingling, low mood — all red flags you shouldn’t ignore. Check your homocysteine & methylmalonic acid — not just serum B12."
If these tests reveal a functional deficiency, treatment often involves B12 injections to bypass absorption issues and boost active levels directly.
Vitamin B12 is crucial for maintaining healthy nerve cells and red blood cells. The NHS lists symptoms of a deficiency as rapid breathing, headaches, a sore tongue, muscle weakness, and problems with memory and balance. While a balanced diet provides enough for most, older adults, vegetarians, vegans, and those with conditions like Crohn's disease may be at higher risk.
