By Dr. Mercola, March 01 2012
Levitical guidelines label the pig an "unclean" animal, and prohibit the consumption of pork.
Regardless of your spiritual beliefs, there may be good reason to carefully consider your decision to include pork as part of your diet, as despite advertising campaigns trying to paint pork as a "healthy" alternative to beef, research suggests it may be hazardous to your health on multiple levels.
Pork consumption has a strong epidemiological association with cirrhosis of the liver -- in fact, it may be more strongly associated with cirrhosis than alcohol (although some have questioned the studies that indicate this, and point out that countries with high pork consumption tend to have low obesity rates.)
Other studies also show an association between pork consumption and liver cancer as well as multiple sclerosis.
What's behind this data?
Most U.S. Pigs are Fed Grains, Making Them High in Inflammatory Omega-6 Fats
One contributing factor is the diet upon which the pigs are raised, which will impact the level of polyunsaturated omega-6 fat it contains.
Too many polyunsaturated fats (PUFAs) contribute to chronic inflammation, which causes all sorts of problems over the long-term. Inflammation is at the source of just about every chronic disease we see today.
Most pigs raised in the United States are fed grains and possibly seed oils, which dramatically increase their omega-6 content, as well as the highly inflammatory byproduct of omega-6 fatty acid metabolism: arachadonic acid. According to the Weston A. Price Foundation, lard from pigs fed this type of diet may be 32 percent PUFAs. On the other hand, lard from pigs raised on pasture and acorns had a much lower PUFA content, at 8.7 percent, while those fed a Pacific Island diet rich in coconut had even less, only 3.1 percent.i
About one third of the staff at Mercola.com is based in the Philippines where pork is a very popular part of their diet. However, unlike the U.S. in which most of the pigs are fed grains, most of the pig diet in the Philippines is vegetable based. My staff tells me that there is a dramatic difference in the taste. So it is possible that many of the adverse consequences being ascribed to pork may be related to the pigs' diet.
As reported by Dr. Paul Jaminet, a trained astrophysicist and his wife Shou-Ching, a Harvard biomedical scientist, who together authored the book Perfect Health Diet:
"So the omega-6 content can cover a 10-fold range, 3% to 32%, with the highest omega-6 content in corn- and wheat-fed pigs who have been caged for fattening. Corn oil and wheat germ oil are 90% PUFA, and caging prevents exercise and thus inhibits the disposal of excess PUFA. Caging is a common practice in industrial food production."
Consumption of this PUFA-rich meat may very well be a factor in liver disease, as studies show feeding mice corn oil (rich in omega-6) and alcohol (which is metabolically similar to fructose) induces liver disease,ii and omega-6 fats have also been linked to cirrhosis of the liver.
However, even though most pork in the United States is likely to be high in omega-6 fats, it is not the largest contributor of omega-6 fats in the U.S. diet -- this honor goes to vegetable oils. Dr. Jaminet continues:
"Either fructose or alcohol can react with polyunsaturated fat to produce liver disease. Sugar consumption, for example in soft drinks, may be just as likely to combine with pork to cause a cirrhotic liver as alcohol. But no other common dietary component can substitute for the role of polyunsaturated fat in causing liver disease.
… We would expect that if pork can cause liver cirrhosis it will also promote liver cancer, since injured and inflamed tissues are more likely to become cancerous. Indeed, there is an association between pork consumption and the primary liver cancer. … But fat composition is hardly likely to be the sole issue with pork. Most polyunsaturated fats in modern diets are derived from vegetable oils, not pork. It seems that there must be something else in pork besides polyunsaturated fat that is causing liver disease."
Most Pork is Consumed in Processed Form
Another reason to reconsider pork, in theory, would be the fact that most is consumed in processed form. Dr. Jaminet reports that in the U.S., pork consumption can be broken down as follows:
Smoked ham 28% Sausage 13% Bacon 6% Processed lunchmeat 6% Other forms of processed pork 10% Processed meats are those preserved by smoking, curing or salting, or the addition of chemical preservatives. Particularly problematic are the nitrates that are added to these meats as a preservative, coloring and flavoring. The nitrates found in processed meats are frequently converted into nitrosamines, which are clearly associated with an increased risk of certain cancers. It's for this reason that the USDA actually requires adding ascorbic acid (vitamin C) or erythorbic acid to bacon cure, as it helps reduce the formation of nitrosamines.
Meat cooked at high temperatures, as many processed meats often are, can also contain as many as 20 different kinds of heterocyclic amines, or HCAs for short. These substances are also linked to cancer. Heating meat at high temperatures also appears to increase the formation of nitrosamines, with well-done or burned bacon having significantly more nitrosamines than less well-done bacon.
Many processed meats are also smoked as part of the curing process, and smoking is a well-known cause of carcinogenic polycyclic aromatic hydrocarbons, which enter your food during the smoking process.
So it's known that eating processed meats exposes you to at least three cancer-causing substances: nitrates and nitrites (leading to nitrosamines), heterocyclic amines, and polycyclic aromatic hydrocarbons. Ironically, despite this known connection, Dr. Jaminet reports that liver cancer appears to be even more strongly associated with the consumption of fresh pork than processed pork, which suggests another causative factor.
Does Pork Contain an Infectious, Disease-Causing Pathogen?
This is the conclusion reached by Dr. Jaminet, who suggests that an infectious pathogen in pork is responsible for the associated health conditions including liver disease and multiple sclerosis:
"Consider: Traditional methods of processing pork, such as salting, smoking, and curing, are antimicrobial. They were developed to help preserve pork from pathogens. So if processed pork is less risky than fresh pork, we should look for a pathogen that is reduced in number by processing.
If a pathogen is the cause, then it makes sense that fiber would be protective [fiber consumption is protective against pork-induced cancer]. Fiber increases gut bacterial populations. Gut bacteria get "first crack" at food and release proteases and other compounds that can kill pathogens. Also, a large gut bacterial population makes for a vigilant immune system at the gut barrier, making it more likely that pathogens will fail to enter the body. The gut flora are a valuable part of the gut's immune defenses."
So while pork is arguably "good" meat from a biochemical perspective, I believe there is enough scientific evidence to justify the reservations or outright prohibitions in many cultures against consuming it. Pigs are scavenger animals and will eat just about anything, alive, sick or dead. Their appetite for less-than-wholesome foods makes pigs a breeding ground for potentially dangerous infections. Even cooking pork for long periods is not enough to kill many of the retroviruses and other parasites that many of them harbor.
This is why my nutrition plan recommends consciously avoiding pork whenever possible.
Granted, the occasional consumption of pork might be fine, but it's a risk, and the more you consume it the more likely it is that you will eventually acquire some type of infection. The pork and swine industry has been continually plagued, and continues to be so to this day, by a wide variety of hazardous and deadly infections and diseases, including:
PRRS -- A horrendous disease, which I first reported on in 2001, but which had been a nightmare for many nations since the mid-1980s, is still alive and kicking today. At one point referred to as "swine mystery disease," "blue abortion," and "swine infertility," the disease was finally named "Porcine Reproductive and Respiratory Syndrome" (PRRS), and may afflict about 75 percent of American pig herds.
The PRRS virus primarily attacks the pig's immune system, leaving its body open to a host of infections, particularly in the lungs. Initial research revealed that the virus was transmitted via semen, saliva and blood, leaving pigs herded closely together and transported in close quarters by trucks more susceptible to infection.
However, according to research presented at the 2007 International PRRS Symposium, the disease is also airborne, making eradication efforts very difficult.
The Nipah Virus – Discovered in 1999, the Nipah virus has caused disease in both animals and humans, through contact with infected animals. In humans, the virus can lead to deadly encephalitis (an acute inflammation of your brain). I originally reported on this virus in 2000, but according to CDC data, the Nipah virus reemerged again in 2004.iii
Porcine Endogenous Retrovirus (PERV) – According to a study in the journal Lancet, this virus can spread to people receiving pig organ transplants, and according to test tube studies, PERV strains do have the ability to infect human cells.iv PERV genes are scattered throughout pigs' genetic material, and researchers have found that pig heart, spleen and kidney cells release various strains of the virus.
Menangle Virus – In 1998, it was reported that a new virus infecting pigs was able to jump to humans. The menangle virus was discovered in August 1997 when sows at an Australian piggery began giving birth to deformed and mummified piglets. Is Organic, Pastured Pork Healthy?
If you choose to eat pork, I would recommend seeking a naturally raised, pastured source, as there's no question that pigs raised on CAFOs will not only be higher in omega-6 fats, but also may be more likely to harbor disease, not to mention be treated inhumanely.
That said, I can't even safely recommend consuming pasture-raised pork, because of a study in Emerging Infectious Diseases citing concerns about pastured pigs being vulnerable to Trichinella spiralis infection, due to their exposure to wild hosts that carry the disease.v
I would also seek out pork that was raised primarily on vegetables rather than grains. Pasture-raised pig farming has expanded with increased demand from health conscious consumers, and that study noted 28 U.S. farms were located within 50 kilometers of a previously infected site.
If you still want to continue buying pasture-raised pork, I'd advise you to at least take a look at this CDC map, which details areas where outbreaks have occurred, to avoid purchasing meat from a potentially unsafe location. Other than that, I would simply recommend you consider avoiding pork altogether, even organic pasture-raised versions, in favor of healthier and safer protein sources, like organic grass-fed beef, lamb, bison and chicken.
i Weston A. Price Foundation November 25, 2011 ii J Nutr. 2004 Apr;134(4):904-12. iii Emerging Infectious Diseases Volume 10, Number 12—December 2004 iv Lancet. 1998 Aug 29;352(9129):692-4. v Emerging Infectious Disease Volume 14, Number 7—July 2008 Source: Perfect Health Diet February 8, 2012 Source: Perfect Health Diet February 15, 2012 Source: Health Correlator February 20, 2012
Related Links: Are There Deadly Superbugs in Your Pork? What are the Most Common Food Infections? Scientific American Finds U.S. Pig Farms May Be 'Flu Factories'