“B12 requires intrinsic factor from the stomach for proper absorption in the ileum. Since the bacterial product does not have intrinsic factor bound to it, it cannot be absorbed (15).

The only reliable and absorbable sources of vitamin B12 are animal products, especially organ meats and eggs (17). Though present in lesser amounts than meat and eggs, dairy products do contain B12. Vegans, therefore, should consider adding dairy products into their diets. If dairy cannot be tolerated, eggs, preferably from free-run hens, are a virtual necessity.”

So it appears that animal sources are key in at least B12, but the nutritional yeast is a good whole food option for the other of B vitamins.

From previous research on B vitamins, they are very complex for the body to break down. If your pee is bright yellow, you may not be metabolizing the B vitamins. The metabolic process (also known as a ‘pathway’) starts in the stomach, for example, converting the cyanocobalamin (a common form of B12) to another form, which is then converted further in the small intestines to a form called methylcobalamin, which is the type of B12 that can circulate in the body and be taken into cells. A majority of B12 is housed in the liver, and recirculates through the small intestines via the bile to offer our cells a steady supply of this essential vitamin.

It’s not uncommon for a person who is ingesting plenty of B rich foods to still be deficient in B vitamins, if there are any digestive issues. This is especially common in anyone who is autistic, or on the autism spectrum. People with digestive disorders which prevent them from metabolizing B vitamins are now taking the methylated forms, with good results.

“It states (exceprt) Some people are exquisitely sensitive to MSG, and if they ingest even a small amount, they experience symptoms such as anxiety, arrhythmia, chest tightness, cramping, depression, diarrhea, dizziness, or migraine. MSG is often “hidden” in products under different names, such as autolyzed yeast, calcium caseinate, glutamate, hydrolyzed protein, yeast extract, and yeast food. It’s also an ingredient in bouillon, broth, malt extract, maltodextrin, smoke flavoring, soy protein, soy sauce extract, whey extract, and flavorings (including “natural flavoring”), and it is found in slow-cooked meats (stews, pot roast, etc). People who are highly sensitive to MSG should avoid those foods whenever possible.”

http://www.thecompounder.com/answers-a-ideas/things-to-avoid/msg-in-food/msg-a-gelatin

http://www.msgmyth.com/discus/messages/320/386.html?1183157183

http://www.welikeitraw.com/rawfood/2005/06/bragg_liquid_am.html

http://www.msgmyth.com/discus/messages/3/1044.html?1256858284

http://msgmyth.com/hidename.htm