In the real world, the most immediate risk is often not the molecule it is the supply chain
Vitamin B12 works synergistically with folate (vitamin B9) in cellular processes
Moreover, folic acid from feed was converted to natural folate vitamers, especially 5-methyl-THF 492,536,537,538,539,540,541,542
doi:10.1042/AN20100033 Lukashev M, Zeng M, Goelz S, Lee D, Linker R, Drukach B, VanDam A (2007) Activation of Nrf2 and modulation of disease progression in EAE models by BG-12 (dimethyl fumarate) suggests a novel mechanism of action combining anti-inflammatory and neuroprotective modalities
"Long-term acetyl-L-carnitine treatment in Alzheimer's disease." Neurology 1991;41(11):1726-32