The BBC documentary was well produced and edited but it did not manage to comment on the wider issues surrounding variant CJD such as growth hormones and vaccines see
https://sites.google.com/site/foodsaf..
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Bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, is a neurodegenerative disease of cattle. Symptoms include abnormal behavior, trouble walking, and weight loss. Later in the course the cow becomes unable to move. The time between infection and onset of symptoms is generally four to five years. Time from onset of symptoms to death is generally weeks to months.

BSE is thought to be due to an infection by a misfolded protein, known as a prion. Cattle are believed to have been infected by being fed meat-and-bone meal (MBM) that contained the remains of cattle who spontaneously developed the disease or scrapie-infected sheep products. The outbreak increased throughout the United Kingdom due to the practice of feeding meat-and-bone meal to young calves of dairy cows. Cases are suspected based on symptoms and confirmed by examination of the brain.

Cases are classified as classic or atypical, with the latter divided into H- and L types. It is a type of transmissible spongiform encephalopathy (TSE).

Efforts to prevent the disease in the UK include not allowing any animal older than 30 months to enter either the human food or animal feed supply. In Europe all cattle over 30 months must be tested if they will become human food. In North America tissue of concern, known as specified risk material, may not be added to animal feed or pet food. About 4.4 million cows were killed during the eradication program in the UK.

BSE is an infectious disease believed to be due to a misfolded protein, known as a prion. Cattle are believed to have been infected from being fed meat and bone meal (MBM) that contained the remains of other cattle who spontaneously developed the disease or scrapie-infected sheep products. The outbreak increased throughout the United Kingdom due to the practice of feeding meat-and-bone meal to young calves of dairy cows.

Prions replicate by causing other normally folded proteins of the same type to take on their misfolded shape, which then go on to do the same, leading to an exponential chain reaction. Eventually, the prions aggregate into an alpha helical, beta pleated sheet, which is thought to be toxic to brain cells.

The agent is not destroyed even if the beef or material containing it is cooked or heat-treated. Transmission can occur when healthy animals come in contact with tainted tissues from others with the disease. In the brain, the agent causes native cellular prion protein to deform into the misfolded state, which then goes on to deform further prion protein in an exponential cascade. This results in protein aggregates, which then form dense plaque fibers. Brain cells begin to die off in massive numbers, eventually leading to the microscopic appearance of "holes" in the brain, degeneration of physical and mental abilities, and ultimately death.

The British Government enquiry took the view that the cause was not scrapie, as had originally been postulated, but was some event in the 1970s that was not possible to identify.

Spread to humans is believed to result in variant Creutzfeldt–Jakob disease (vCJD). The agent can be transmitted to humans by eating food contaminated with it. The highest risk to humans is believed to be from eating food contaminated with the brain, spinal cord, or digestive tract though any tissue may be involved.

Variant Creutzfeldt–Jakob disease (vCJD) is a type of brain disease within the transmissible spongiform encephalopathy family. Symptoms include psychiatric problems, behavioral changes, and painful sensations. The length of time between exposure and the development of symptoms is unclear, but is believed to be years. Average life expectancy following the onset of symptoms is 13 months.

It is caused by prions, which are mis-folded proteins. Spread is believed to be primarily due to eating bovine spongiform encephalopathy (BSE)-infected beef. Infection is also believed to require a specific genetic susceptibility. Spread may potentially also occur via blood products or contaminated surgical equipment. Diagnosis is by brain biopsy but can be suspected based on certain other criteria. It is different from classic Creutzfeldt–Jakob disease, though both are due to prions.

Treatment for vCJD involves supportive care. As of 2012 about 170 cases of vCJD have been recorded in the United Kingdom, and 50 cases in the rest of the world. The disease has become less common since 2000. The typical age of onset is less than 30 years old. It was first identified in 1996 by the National CJD Surveillance Unit in Edinburgh.