A comment in a previous post peaked my interest.
I found this on LiveStrong.
Bovine pituitary extract is a potential source of infectious agents.
Bovine pituitary extract, or BPE, is a filtered, water-based extract of fresh pituitary glands from cattle. As a source of growth factors and hormones, BPE is used in tissue culture research to support various cell lines, such as skin, breast, lung and prostate. You might consider taking BPE to address any number of issues, including thyroid, growth, reproductive or adrenal problems. However, the evidence of benefit from such use is limited, and you could risk exposure to infectious agents, including those that cause "mad cow disease."
Your pituitary gland -- and those of all mammals -- produces a variety of hormones with wide-reaching physiologic effects. Your thyroid gland, adrenal glands, bones, muscles, breasts, kidneys and gonads are all directly influenced by pituitary hormones. Growth, reproduction, body temperature, fluid and electrolyte balance, blood pressure, stress response, milk production and general metabolic rate are governed by your pituitary. It isn't clear if all pituitary hormones from one species exert beneficial effects in another, particularly when they are introduced through your gastrointestinal tract. However, it is clear that diseases can be spread between species through consumption of brain tissue.
Prions -- proteinaceous infectious particles -- are misshapen or mis-folded proteins which, when introduced into your tissues, can induce your normal proteins to assume the mis-folded state. Although they are not viruses, prions behave like viruses in that they can serve as templates to trigger a chain reaction of prion formation in your tissues, most notably in your brain. A February 2004 review in the German journal "Gesundheitswesen" states that scrapie, a prion-based disease in sheep, was first described in 1750. A similar disorder in cows was described around 1850, and Kuru, or Creutzfeldt-Jacob disease, was first reported in cannibalistic humans in the 1920s.
The prion-induced disease of cattle, called bovine spongiform encephalopathy, BSE or "mad cow" disease, has emerged at various times in multiple countries but has been most prominent in the United Kingdom. BSE causes a fatal, degenerative neurologic disease in affected animals. In 1996, 10 cases of "new variant" Creutzfeldt-Jacob disease, or vCJD, were diagnosed in humans in the U.K. As of 2010, 219 cases of vCJD -- all believed to have resulted from consumption of prion-infected beef products -- had been diagnosed worldwide. Like BSE in cattle, vCJD in humans is ultimately fatal.
Even though bovine pituitary extract is produced using material from BSE-free herds, prion diseases can take years to develop. Therefore, there is some risk, although small, of acquiring vCJD from taking BPE. In 2001, Dr. Per Lundberg, a neuroanatomist at Sweden's Uppsala University, recommended against consumption of bovine brain, spinal cord, intestine, lymphatic tissue or lungs. The consumption of products obtained from fresh bovine pituitary tissue -- particularly when no proven benefit can be ascertained -- should be approached with caution. Ask your doctor if BPE is appropriate for you.