vitamin · for eye strain
Vitamin B12
Supports the nerves that run your eyes, including the muscle that does the focusing.
Say that in clinical terms
Methylcobalamin supports optic nerve myelin sheath integrity and corneal nerve health. It modulates homocysteine levels that can damage retinal vasculature and may improve accommodative function of the ciliary muscle, reducing focusing fatigue.
How strong is the research?
2 papers read, 1 supporting.
Who was studied: Studied in people with a diagnosed focusing disorder, not everyday screen fatigue.
How much to take
daily
1000 mcg
B12 supports optic nerve health and may reduce accommodative eye fatigue.
Before you take it
- No NIH ODS or IOM Tolerable Upper Intake Level (UL) has been established for vitamin B12 in any form; the IOM found no adverse effects attributable to excess intake from food or supplements in any population studied and set no UL.
- Metformin significantly reduces B12 absorption by impairing calcium-dependent membrane action in the terminal ileum; patients on long-term metformin are at elevated risk of B12 deficiency and should have serum B12 monitored periodically.
- Proton pump inhibitors (PPIs) and H2-receptor antagonists reduce gastric acid secretion needed to release protein-bound dietary B12, thereby reducing absorption from food; this effect is substantially less pronounced for free supplemental B12 forms.
- High-dose folic acid supplementation can mask the hematological signs of B12 deficiency (megaloblastic anemia), potentially allowing neurological damage from covert B12 deficiency to progress undetected.
- Rare anaphylactic reactions have been reported with parenteral (injectable) B12 preparations; no equivalent hypersensitivity risk has been established for oral or sublingual supplemental forms.
- Individuals with Leber's hereditary optic neuropathy should avoid high-dose cyanocobalamin; methylcobalamin is the preferred supplemental form when B12 supplementation is clinically indicated in this population.
When to take it
Best taken: morning
What we make of it
The paper we cite turns out to be about a myopia gene, not B12.
The detail
Searching the identifier we stored returns a study on a collagen gene and short-sightedness, with no B12 in it. The closest real evidence is a 1987 Japanese study of methylcobalamin and eye focusing — old, small, and never repeated.