recent high levels of solar activity *may* have effected B12 levels negatively (i felt it) — this study was done only on men; i would guess women are even more sensitive to it given risk of iron deficiency & anemia are higher for women & lack of B vitamins can be a cause. *i am not a doc*

“Reduced levels of B12 vitamin or folate affect the production of red blood cells that can evolve to anemia and to detrimental impact on the nervous system health. In periods of intense solar activity, solar ionizing radiation such as UVB and UVC, X-rays, gamma and solar energetic particles are emitted from the Sun, reaching the Earth systems, modifying the homeostasis of the living beings which may include detrimental B12 and folate oscillations.”

“In addition, recent studies have shown that the general population has similar adverse health symptoms related to solar activity oscillations to those observed in astronauts, although less acute and intense. Similarly, B-complex deficiencies have been observed in astronauts. The adverse impact of space weather radiation exposures on B-complex levels in astronauts is also linked to a decrease in mitogen proliferation that reduces immune-inflammatory cells such as Peripheral Blood Mononuclear Cells (PBMCs) and lymphocytes (type of white blood cells), and thus weakens the immunological system.”

https://www.nature.com/articles/s41598-024-56916-3#ref-CR34