Over the years, I’ve seen my share of patients who feel fatigued. Many of them also have related symptoms – brain fog, weakness, numbness or tingling in the hands or feet, even trouble walking. Some complain of always feeling cold. Others say their mood is off or that their memory is starting to slip.
These symptoms, combined with low energy levels, are a clear warning sign to me: these patients may be deficient in a single nutrient. One that is critical to every cell in the body – vitamin B12.
Let’s take the case of a 70-year-old man. He was experiencing some neuropathy, had trouble walking in a straight line, and showed signs of muscle weakness.
⚠️The Hidden Culprits Behind B12 Deficiency
As it turned out, he was severely deficient in vitamin B12. After just three weeks of B12 injections, his symptoms began to improve dramatically.
But the real question was – what caused his deficiency in the first place?
Well, the big clue was that fact that he had been taking nitrous oxide every time he went to the dentist. He had been going three or four times a year for the past 30 years. And he wouldn’t let them touch him until they gassed him up.
What he didn’t know – and no one ever told him – is that nitrous oxide destroys your body’s stores of vitamin B12. Not once had anyone suggested he have his B12 levels tested.
Sadly, this isn’t an isolated case.
It’s the same for people who take metformin. They lose B12, but doctors often fail to inform them that they need to either get injections or take sublingual B12 under the tongue, using either the liquid form or dissolvable tablets.
You’ve also got people who take Tagamet, Pepcid, or one of the proton pump inhibitors (Prilosec, Nexium, Prevacid). These heartburn meds pretty much stop you from breaking down and absorbing any B12 from your foods.
And what if you’ve had gastric bypass surgery?
I had a patient come in who had gastric bypass with staples and had all the symptoms of B12 deficiency. I asked about whether or not they were receiving their weekly B12 shots. The response was “nobody ever told I needed them.” Once the shots were administered, it was just a matter of weeks before symptoms started going away.
🧓Why Age Matters
Even without medications or surgeries, aging itself can reduce your B12 absorption. As we get older, our stomachs produce less acid and fewer digestive enzymes – both of which are needed to extract B12 from food. So even if you get plenty of B12 in your diet and have no other contributing factors, you can still become deficient.
That’s why older adults are especially at risk for deficiency, even with a seemingly healthy diet.
Unfortunately, this is something most people don’t realize, and many physicians overlook when patients present with neuropathy, memory issues, or balance problems.
If you’re lucky, your physician is familiar with B12 deficiency and symptoms – and routinely tests serum or urine methylmalonic acid to diagnose deficiency.
If your levels are low, chances are good he will recommend intramuscular injections of vitamin B12. This way the vitamin is absorbed directly into the bloodstream. It bypasses the digestive process altogether.
Then, he or she should transition you to a sublingual B12 spray. Using the sublingual version bypasses malabsorption issues.
In the meantime, if you’re taking acid-suppressing proton pump inhibitors to ease digestive issues, I recommended addressing the underlying source of your stomach upset so that you can stop taking them.
Somewhere around half of patients who complain of heartburn don’t actually have excess stomach acid. Instead, they don’t have enough of it. This is especially true among those 60 and older.
A simple home test will help you figure out if that’s what is happening with you. Just take a tablespoon of apple cider vinegar when heartburn strikes. If the pain disappears, that’s a pretty good indication that your body isn’t producing enough hydrochloric acid.
If that’s the case, you can take 600 mg of HCI at the beginning of each meal to resolve your symptoms – without destroying your stores of vitamin B12.
SOURCES:
Vitamin B12 Deficiency. BMJ Best Practice. Last updated: Sep 2025.
Flippo TS, Holder WD Jr. Neurologic degeneration associated with nitrous oxide anesthesia in patients with vitamin B12 deficiency. Arch Surg. 1993 Dec;128(12):1391-5.
Swarnakari KM, Bai M, Manoharan MP, Raja R, Jamil A, Csendes D, Gutlapalli SD, Prakash K, Desai DM, Desai A, Khan S. The Effects of Proton Pump Inhibitors in Acid Hypersecretion-Induced Vitamin B12 Deficiency: A Systematic Review. Cureus. 2022 Nov 19;14(11):e31672.
Miller JW. Proton Pump Inhibitors, H2-Receptor Antagonists, Metformin, and Vitamin B-12 Deficiency: Clinical Implications. Adv Nutr. 2018 Jul 1;9(4)
Al Mansoori A, Shakoor H, Ali HI, Feehan J, Al Dhaheri AS, Cheikh Ismail L, Bosevski M, Apostolopoulos V, Stojanovska L. The Effects of Bariatric Surgery on Vitamin B Status and Mental Health. Nutrients. 2021 Apr 20;13(4):1383.
