Pork is the most commonly consumed meat in the world, but it could also be one of the most dangerous because of some rarely-discussed but important risks.
Read on to find out what they are and how you can protect yourself.
1. Hepatitis E
Health enthusiasts have recently rediscovered the benefits of eating offal, especially liver which is full of vitamin A and other minerals.
Pork liver, however, may pose some risks.
Pork liver is the top food-based transmitter of hepatitis E, a virus that infects 20 million people each year and can lead to illness with fever, fatigue jaundice, vomiting, joint and stomach pain, and also enlarged liver. These symptoms can lead to liver failure and even death.
Pregnant women can experience bad reactions to the virus, including rapid-onset liver failure, and are at high risk of maternal and fetal fatality – mothers who are infected during the third trimester risk a death rate of up to 25%.
Hepatitis E can also lead to pancreatitis, which is a very painful inflammation of the pancreas, inflammatory heart disease, neurological problems, blood disorders and musculoskeletal problems.
How common is the contamination in pork?
In America, around 1 in 10 store-bought pig livers tests positive for hepatitis E, which is just a bit higher than the 1 in 15 in the Netherlands, and 1 in 20 in the Czech Republic. In Germany, one study found that around 1 in 5 pork sausages were contaminated.
France have a traditional pig liver sausage called figatellu, which is often eaten raw. It’s a confirmed hepatitis E carrier, and in regions of France where raw pork is commonly eaten, over half the local population shows evidence of hepatitis E infection.
There are rising concerns over hepatitis E in Japan too, as pork grows in popularity there. In the UK, hepatitis E shows up in pork sausages, pork liver and at pork slaughterhouses.
Wild boars too, can carry hepatitis E, so eating wild pigs isn’t necessarily safer than commercially farmed ones.
The best way to reduce the risk of hepatitis E starts in the kitchen. The virus can survive in rare-cooked meat, which means that using high heat to cook pork is the best way to protect against infection. Cooking pork for at least 20 minutes to an internal temperature of 160F (71C) seems to be the best way to go. Fattier cuts of pork might need extra cooking time or hotter temperatures, as fat can protect the hepatitis viruses from destruction.
2. Multiple Sclerosis
This may be one of the most surprising risks associated with eating pork, and one that is very rarely discussed. Multiple sclerosis (MS) is a damaging autoimmune condition that involves the central nervous system.
The link between pork and MS has been known since the 1980’s, when researchers studied the relationship between pork consumption and MS across a large number of countries.
Nations that don’t eat much pork, such as Israel and India, have far less incidences of MS compared to countries like West Germany and Denmark.
Between 2007 and 2009, a group of 24 pork plant workers fell ill with a mysterious progressive inflammatory neuropathy. This is characterized by symptoms similar to MS, with fatigue, numbness, tingling and pain.
The source of the outbreak was traced back to what’s called “pig brain mist”, which is tiny particles of brain tissue that’s blasted into the air during the carcass processing. The workers inhaled these small tissue particles, and their immune systems formed antibodies to fight the antigens in the pig brain. The antigens confused the workers immune systems, so that they launched an attack on their own nerve tissue. MS works in a similar way, using antigens that trigger an autoimmune response.
Pigs may also be carriers of prions, which are misfolded proteins which can facilitate neurodegenerative disorders such as Creutzfeldt-Jakob disease (the human type of BSE, or “mad cow disease”) and Kuru (a disorder found among cannibalistic societies).
There has been some research to suggest MS could be a prion disease – one that targets oligodendrocytes, the cells that produce myelin. As prions are transmitted through infected nerve tissue, it’s quite possible that pigs carrying the prions could be one link in the chain that leads to MS.
3. Liver Cancer and Cirrhosis
Hepatitis B and C infection, exposure to aflatoxin (a cancer-causing substance produced by mold) and excessive consumption of alcohol can all lead to liver problems. There also seems to be a link between liver issues and pork.
In statistical models including known problem causers for the liver, such as alcohol, hepatitis B and C infection, pork remained independently associated with liver disease. This suggests that pork isn’t just an addition to a different causative agent, but could be one in its own right. Beef remained liver-neutral or even protective in the same studies.
Pork has also been linked with liver cancer, but why is this the case?
Other meats aren’t as high in omega-6 fatty acids as pork, and this may play a role in liver disease. It’s worth noting, though, that vegetable oils with higher polyunsaturated fatty acid content than pork don’t seem to cause liver disease in the way that pork may do.
One possible source is nitrosamines – cancer-causing compounds created when nitrites and nitrates react with some amines from protein. Processed pork is one of the biggest dietary sources of nitrosamines, and significant amounts of them have been found in pork liver pate, bacon, sausage, ham and other cured meats. Bacon has high levels because the fatty portion of pork products tends to build up higher amounts of nitrosamines than the lean parts.
The evidence is too scarce currently to say for sure that there is a link between pork, nitrosamines and liver disease, but there could be enough in it to justify cutting down or cutting out pork products like bacon, ham, hot dogs and sausages made with sodium nitrite or potassium nitrate.
For many years, we stuck to the advice to cook pork thoroughly to avoid a type of roundworm infection that caused problems for pork eaters through most of the 20th century.
Modern farming hygiene and feeding practices mean that pig-borne roundworms are not much of a risk anymore. This means that it’s now safe to eat pink pork without catching worms, but there is a consequence of this – yersiniosis.
The Yersinia bacteria causes 35 deaths and almost 117,000 cases of food poisoning each year in the US alone. The main entry route for these bacteria is through undercooked pork.
The symptoms of yersiniosis are bad enough, including fever, pain and bloody diarrhea, but the long-term consequences can be brutal. Victims of Yersinia poisoning face a 47 times higher risk of contracting reactive arthritis – a type of inflammatory joint disease triggered by infection. Even children can contract this arthritis after having yersiniosis, leading to injections of osmic acid into problem joints to lessen the pain.
Reactive arthritis usually goes away on its own over time, but Yersinia victims still remain at higher risk of chronic joint problems, including sacroiliitis, rheumatoid arthritis and tenosynovitis for many years.
Yersinia has also been linked with neurological complications, liver abscesses and Graves’ disease among others.
The solution is to make sure pork is properly cooked through, to an internal temperature of at least 145F for whole pork, and 160F for ground pork to ensure the bacteria are killed.