Yep, the conflicting information is all OVER the place!
The article by Cousins basically confirms everything I've researched and concluded. The article confirms that Red Star is a bio-available source of B12, but his disinformation regarding Red Star yeast having the potential for fungal issues is appalling.
Something in my heart tells me that spirulina is also a good source (even though it doesn't test out that way in laboratories). I've never seen actual clinical trials with humans regarding spirulina & B12. It's all 'theorized via scientific knowledge of the body' (and we know how good those theories are).
Here's a blurb from wikipedia on Spirulina and how it's been tested:
>>>Spirulina contains vitamin B1 (thiamine), B2 (riboflavin), B3 (nicotinamide), B6 (pyridoxine), B9 (folic acid), vitamin C, vitamin D, and vitamin E. The bioavailability of vitamin B12 in Spirulina is in dispute. Several biological assays have been used to test for the presence of vitamin B12. The most popular is the US Pharmacopeia method using the Lactobacillus leichmannii assay. Studies using this method have shown Spirulina to be a minimal source of bioavailable vitamin B12. However, this assay does not differentiate between true B12 (cobalamin) and similar compounds (corrinoids) that cannot be used in human metabolism. Cyanotech, a grower of spirulina, claims to have done a more recent assay, which has shown Spirulina to be a significant source of cobalamin. However the assay is not published for scientific review and so the existence of this assay is in doubt. The American Dietetic Association and Dietitians of Canada in their position paper on vegetarian diets state that spirulina can not be counted on as a reliable source of active vitamin B12.<<<
Once again, it's all conjecture.
My 'doctor/teacher within' knows that the human body does amazingly *impossible* things all the time, and it's certainly possible that our bodies could make the B12 in spirulina 'bio available' no matter WHAT the 'scientific powers that be' theorize & publish.
BUT, until someone does a double-blind study with humans (that has absolutely NO conflict of interest), there's really no way to know for sure.
If there were any long-term vegans out there that have ONLY used spirulina as a source of B12, then we'd at least have a clue. But there's a huge variety of B12 fortified foods on the vegan market (yeast extracts, Vecon vegetable stock, veggieburger mixes, textured vegetable protein, soya milks, vegetable and sunflower margarines, and breakfast cereals)...so 'anecdotal evidence' might not be very reliable.