PMC 2148293
[76] Ruminants, such as cows and sheep, are foregut fermenters, meaning that plant food undergoes microbial fermentation in the rumen before entering the true stomach (abomasum), thus allowing them to absorb the vitamin B 12 produced by the bacteria
Without adequate intake of B12, vegans can easily develop deficiency over time, leading to symptoms such as fatigue, weakness, constipation, loss of appetite, weight loss, and nerve problems therefore the researchers recommend that vegans and vegetarians should add vitamin B12 to their diet by eating fermented foods, particular types of mushroom that contain the vitamin and B12-enriched vegetables
Neither type directly burns fat in people without deficiency
However, B-12 injections ensure you get the right levels of B-12 and that you receive it in the form that your body can most readily absorb and utilize by your body and which will not be broken down through digestion
A healthy adult with normal B12 levels should have around 3 to 5 years' worth of B12 stored in their body