COVID’s Lingering Fog? Don’t Ignore This Warning Sign

For many, the pandemic seems like a distant bad dream.

But for others, it’s a nightmare they can’t wake up from.

Approximately 17 million adults suffer from Long COVID, which occurs when you continue to have health problems long after you’ve been infected with COVID-19.

Cognitive impairment is a common Long COVID symptom that can last weeks… even years.

Fortunately, researchers have identified a nutrient that could help with this debilitating brain fog.

As many as 25 percent of those who had a mild COVID-19 infection develop a form of cognitive impairment that affects visual-spatial skills called visuoconstructive deficit (VCD).

Ultimately, VCD impacts memory, attention, and problem-solving abilities. Studies show that people with VCD have changes in their brain scans and increased immune system activity.

For the study, researchers recruited volunteers who were diagnosed with VCD 10 to 16 months after having a mild COVID-19 infection, as well as healthy controls who had recovered without a VCD diagnosis.

The researchers found that participants with VCD had increased cellular levels of CCL11, a type of signaling molecule that attracts immune cells to specific locations.

Higher levels of CCL11 are linked to age-related neurogenerative diseases.

When researchers added vitamin B12 to blood samples from the participants with VCD, some remarkable changes occurred:

• First, the gene activity for CCL11 returned to normal levels, suggesting B12 may improve cognitive function in Long COVID.
• Second, vitamin B12 increased the activity of genes for HGF (hepatocyte growth factor). HGF protects the brain by supporting nerve cell survival and potentially repairing damaged brain tissue.
• Third, it decreased the activity of two specific inflammatory markers (CSF2 and CXCL10) associated with brain inflammation.

Perhaps most interesting was how vitamin B12 worked its magic. The researchers discovered that B12 helps modify how genes are turned on and off—specifically by changing the chemical tags on the CCL11 gene, effectively turning down its activity.

This lab study did NOT directly test whether B12 improves VCD symptoms in people with Long COVID.

Instead, it identified key ways that vitamin B12 might combat the cognitive decline that some experience with the condition.

More research is needed to see how that translates to everyday life for those with VCD.

However, B12 is a safe, affordable, and readily available supplement. So, in the meantime, if you’re experiencing any of the cognitive symptoms of Long COVID, supplementing with vitamin B12 may be worth discussing with your doctor.

P.S. Slash the severity of your Long Covid symptoms with these potent inflammation fighters.

View Sources

Cassiano, L.M.G., de Paula, J.J., Rosa, D.V. et al. Vitamin B12 as an epidrug for regulating peripheral blood biomarkers in long COVID-associated visuoconstructive deficit. Sci Rep 15, 9438 (2025).