i found one of the highest quality b12s...check it out:
https://www.globenewswire.com/news-...ents-to-Reduce-Pollution-Impact-on-Earth.html
found in the seeking health brand b12 lozenges. i've had the best effects yet with the Mecobalactiv b12. much better than jarrow. it's a combination methylcobalamin/adenosylcobalamin b12.
“The production of the methylcobalamin form of B12 can be a contaminating process and typically involves using methyl iodide, a very volatile chemical classified as a prop 65 carcinogen, or dimethylsulfate which is another carcinogen and environmentally hazardous material,” said Cai Berg, president of Berg Nutrition. “This is why sometimes you will see the price of vitamin B12 spike in the winter. It’s because factories in other parts of the world must literally shut down for several months due to residents complaining of air pollution.”
this might explain some of the negative effects of cheaper b12s.
"MecobalActive is a European methylcobalamin form of B12 produced in Sant-Cugat, Barcelona, Spain by using dimethyl carbonate, which is environmentally innocuous and non-toxic and creates a harmless biodegradable byproduct. In Japan, MecobalActive maintains market leader status for its distinctive purity profile and production process that does not contribute to environmental pollution. It is a combination of fewer impurities, sustainability, lower humidity and superior stability that has given MecobalActive a unique position in the vitamin B12 market."
“MecobalActive is more expensive than other methylcobalamins, but you don’t have to overdose it in the finished product because it’s the purest form of vitamin B12 with the lowest amount of impurities and therefore very shelf stable. The lower overage provides a comparable cost in use, in the end,” said Berg.
“It’s the impurities in most vitamin B12 ingredients that influence the stability and causes a shorter shelf life.”