11/04/2025
A recent study has raised concerns that current vitamin B12 recommendations may not be sufficient to protect against cognitive decline, particularly in older adults. Even when B12 levels are within the "normal range," lower levels of active B12 (holo-TC) have been linked to slower cognitive processing and brain changes, such as white matter damage. This is particularly concerning because subtle deficiencies can be missed by standard serum B12 tests, which measure total B12 rather than its bioactive forms.
This highlights the importance of deeper diagnostics, like MMA testing, to detect functional B12 deficiencies that standard tests might miss. Elevated MMA is a more sensitive marker of B12 deficiency, as it reflects impaired cellular function. Additionally, as we age, reduced stomach acid production makes it harder to absorb B12 from food. Causes of low stomach acid include aging, chronic stress, zinc deficiency, infections like H. pylori, and the widespread use of acid-reducing medications called Proton Pump Inhibitors (PPIs), which should be highlighted here.
PPIs can impair vitamin B12 absorption by reducing gastric acid secretion, which is essential for releasing B12 from food proteins, potentially leading to deficiency with long-term use. Studies have shown that prolonged PPI use is associated with lower serum B12 levels and an increased risk of deficiency-related complications such as cognitive decline and neuropathy.
It’s frustrating that although we know low stomach acid is far more common than high stomach acid—and that they share similar symptoms—for some reason this information still isn’t being communicated effectively to GP offices that regularly prescribe PPIs. Older women in my nutrition clinic often suffer from reflux symptoms, digestive upset, and osteopenia or osteoporosis, and I know before they tell me that they have been taking PPIs for some time and have come to me for an alternative approach to supporting their digestion.
When we work on diet, trigger foods, boosting the microbiome, and reducing inflammation in the gut, they feel much better. Supporting stomach acid production naturally through dietary changes can also make a significant difference in improving digestion and nutrient absorption.
Another key nutrient for preventing cognitive decline is vitamin D, and many people are deficient due to limited sun exposure and inadequate dietary intake. We help them understand that unless they have good magnesium levels—which most people don’t—they are also unable to synthesize enough vitamin D. Magnesium acts as a cofactor in the activation of vitamin D both in the liver and kidneys, making it essential for maintaining adequate levels.
Working with a nutrition professional to optimize digestion and ensure proper nutrient absorption can really empower people to support their brain, bone, digestive health, and more as they age, so they stay in good shape for longer. We want not just a good lifespan but a great healthspan.
Current recommended levels of vitamin B12 might not be sufficient to protect against neurological decline.
