Some common side effects of Vitamin B12 include headache, nausea, anxiety, nervousness, diarrhea, swelling, infection, severe itching of skin, loss of coordination and balance
10.1113/jphysiol.2010.194704 7 BaillieJ
L-cysteine supplementation also helps to prevent the downregulation of vitamin D regulatory genes by way of increasing GSH N-Acetylcysteine (NAC) is another form of cysteine that is considered less toxic, less susceptible to oxidation (and dimerization) and is more soluble in water, making it a better source of cysteine than parenteral administration of cysteine itself. GSH is necessary to help protect our cells from damage due to oxidative stress, mercury and other toxic metals, alcohol, persistent organic pollutants, and much more
This rigorous control was implemented to minimize the influence of confounding factors that could otherwise impact the results
While some foods contain glutathione, others support glutathione synthesis with cysteine