The UK Medicine and Healthcare products Regulatory Agency has issued a warning to anyone who has taken the protein, labelled as First Immune and bought through an online website and unregulated sources, saying that they should contact their doctor.
Agency investigators had carried an unannounced inspection of the Milton, Cambridgeshire site.
GcMAf, a controversial product popular in the island, has been claimed to help those with conditions such as cancer and autism.
More to follow in tomorrow's Guernsey Press.
