Dear Dr. Blonz: There was a great deal of publicity about mad cow disease a few years ago, including some distressing videos of suffering cattle and several tragic human deaths. We were advised to cook any beef products very thoroughly, or better yet, to avoid beef altogether. Then the matter dropped off the media world. What became of this topic, and do we still need to overcook all beef? What about products such as gelatin? -- P/RL, Berkeley, California
Dear P/RL: It is good that we haven't heard that much lately about bovine spongiform encephalopathy (BSE), also known as mad cow disease, as it is reflective of good science and effective controls. In people, the disease caused by BSE is a variant of Creutzfeldt-Jakob disease (vCJD), and it is a progressive, ultimately fatal condition that affects the brain and nervous system. Both BSE and vCJD are caused by an abnormal protein, referred to as a "prion," acting as an infectious agent. The term "prion" was coined by University of California San Francisco scientist Stanley Prusiner, who discovered this protein as an infectious entity and won the Nobel Prize for his efforts.
Your comment about cooking is misplaced given that high-heat exposures from cooking, boiling or even microwaving cannot reliably destroy the infectious nature of prions. While they are not airborne and not transmitted by casual contact, prions can be transmitted by contact with infectious bodily fluids or tissues, or the consumption of BSE-contaminated cattle products. The outbreak was first discovered in the United Kingdom in the 1990s, and once the source of the disease was uncovered, it led to the isolation and destruction of thousands of suspect cattle and the institution of rigid control measures.
Worldwide, 95 percent of cases have occurred in the United Kingdom. There continue to be strict import restrictions to prevent BSE-positive cattle from entering the United States. A history of the epidemic in the United Kingdom can be found at tinyurl.com/n9f7u6k. There is also information at the U.S. Centers for Disease Control (tinyurl.com/29zmmhl) and the Food and Drug Administration (tinyurl.com/2wvgxa3).
The risk of BSE led to valid concerns, not only about tainted meat, but about the use of cow byproducts.
Gelatin is a type of protein that can come from bones and hides of cattle, but it usually comes from pork. Irrespective of the animal source, the tissues used to make gelatin are considered by the FDA to be low-risk for the spread of BSE. In addition, the FDA published a guidance in 1997 that prohibits the making of gelatin from high-risk cows (tinyurl.com/nc8t45t).
We next consider the fact that the manufacturing process by which gelatin is made involves acid and alkali treatments and extensive washing coupled with high temperature sterilizations. Each of these steps further reduces risk. While it is always difficult to speak in absolutes, the process does make the risk negligible, and, as such, gelatin retains its "generally regarded as safe" designation as an ingredient in foods, or as an ingredient in medications or dietary supplements.
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