I wrote to the customer service representative of the vitamin manufacturer about the soy in Complex B. They told me their B- 50 contains "trace soy". Though they didn't intend to add it, it is not 100% soy free.They don't list "soy" or "soy bean" in the ingredients. Nor do they list them in the "free" list. Would the "trace soy" in Complex B cause problems?

I would assume that the 'trace soy' is any left on the manufacturing equipment after it has been cleaned after processing a soy based product. The amount of soy left would be very small and should not be a problem.

Not for your thyroid. It's when people are eating that stuff all the time it becomes an issue. Like vegetarians eating meat-replacement things made out of soy.

Now, if you're allergic to soy, perhaps a trace is an issue but otherwise I'd say you're fine.