We started this series with a look at remarkably strong correlations between pork consumption and liver cirrhosis mortality, liver cancer, and multiple sclerosis (Pork: Did Leviticus 11:7 Have It Right?, Feb 8, 2012). In Part 2, we looked at omega-6 fats in industrial pork meat and toxins in processed pork products as possible causes (The Trouble with Pork, Part 2, Feb 15, 2012).
That second post left us with several clues that some pathogen (or pathogens) that (a) infects both pigs and humans and (b) can be transmitted from pigs to humans via the eating of pork, is responsible for the disease associations. These clues include:
- The risk is higher for fresh pork than processed pork. Processed pork is generally cured or smoked, both steps that are anti-microbial.
- Eating fiber, which increases gut bacterial populations and enhances immune vigilance of the gut, is protective.
- The disease risk is specifically associated with two organs – the central nervous system (multiple sclerosis) and the liver (cirrhosis, hepatocellular carcinoma). Pathogens are more likely than other pork components to have tissue specificity.
Our mission today is to try to track down the pathogen(s), and figure out how to minimize risk of infection.
Pigs And Zoonotic Infections
Scientists studying xenotransplantation – the transplantation of animal organs into a person to replace a failing organ – have had the best luck with pig organs. Pigs are easier to work with than primates, not dramatically different in size than humans, and their organs are less likely to provoke rejection than those of other mammals. This suggests a similarity of biology between pigs and humans.
But biological similarity has its downsides. A large number of pathogens can infect both pigs and humans. More than any other animal, pigs pass pathogens to humans.
Indeed, investigators have been surprised at how frequently pathogens pass back and forth. According to a new study (discussed at Aetiology) of the evolutionary history of methicillin-resistant Staphylococcus aureus (MRSA), S. aureus was passed to pigs by their human caretakers. In pigs, which are routinely given antibiotics by industrial food producers, S. aureus picked up resistance genes to tetracyclines and methicillins. The resulting antibiotic-resistant ST398 strain was passed back to humans.
Wikipedia lists some of the pathogens that flourish in both pigs and humans and can infect humans who eat infected pork, usually undercooked pork:
- Pork tapeworm, Taenia solium, not only causes a parasitic infection of the intestines (the worm is typically 2 to 3 meters long) but also the larvae can infect the brain and muscles, causing the disease Cysticercosis which is a common cause of seizures.
- The roundworm Trichinella spiralis causes trichinosis. As in tapeworm infections, the mature worms are largely confined to the intestines where symptoms include nausea, heartburn, dyspepsia, diarrhea, and eosinophilia but larvae can migrate through the body, producing edema, muscle pain, fever, and weakness. The greatest danger is if the larvae reach the brain, where they can cause “serious neurological deficits (such as ataxia or respiratory paralysis), and even death.” Death results from a rare form of stroke, myocarditis, encephalitis, or pneumonia.
- Other helminths including pinworms and hookworms, and ascarid worms. [14]
- Listeria monocytogenes [24].
- E. coli, Salmonella, and Staphylococcus aureus [25].
- Yersinia enterocolitica, which causes gastroenteritis, is nearly always transmitted through pork.[28]
- Brucella spp., the bacteria which cause brucellosis or undulant fever.
- Various viruses, including porcine herpesvirus, rotavirus, parvovirus, and circovirus. Some influenza viruses, such as the famous “swine flu,” have been known to be transmitted from pigs to humans. SARS is an example of a coronavirus which was transmitted from pigs to humans. PERVS (porcine endogenous retroviruses) may also be infectious in humans; of three subgroups of infectious PERVs (PERV-A, PERV-B, and PERV-C), PERV-A and PERV-B have been shown to infect human cells in culture. [24][26]
Although all of these pathogens are potential concerns, I do not see strong specific links between the above pathogens and our three pork-associated diseases – liver cirrhosis, liver cancer, and multiple sclerosis.
However, there is another pathogen capable of infecting humans from pork that is a strong candidate: hepatitis E virus (HEV).
Hepatitis E
Hepatitis E was first observed in a 1955 outbreak in New Delhi, India. It generally produces an acute disease that lasts for several weeks; most victims recover with few symptoms, but in a few this acute illness progresses into a severe liver disease that can be fatal. About 2% of all infections lead to death from this acute liver disease; death rates are higher in pregnant women.
Hepatitis E seems to have evolved in the last millennium: There are four known genotypes, all of which infect humans and two of which infect pigs, and their common ancestor dates to 536 to 1344 years ago. [1] However, the pig-infecting genotypes 3 and 4 of Hepatitis E underwent a notable population expansion in the twentieth century, during which there has been “an extensive genetic divergence of HEV strains and high prevalence of HEV infections in many parts of the world.” [2]
The human-only genotypes of Hepatitis E are transmitted by fecal contamination of drinking water and are prevalent only in developing countries with poor sanitation; but the pig-and-human genotypes are transmitted primarily through pork consumption:
[G]enotypes 3 and 4 are associated with sporadic disease attributable to exposure to body fluids of infected swine [8] and ingestion of food products from pigs, boars and deer [11], [16], [18]. [1]
Hepatitis E seems to be most prevalent in Asia, the Middle East, and Africa:
Hepatitis E is the most important or the second most important cause of acute clinical hepatitis in adults throughout Asia, the Middle East and Africa. [8]
However, it has been spreading to Europe and the Americas:
HEV was rarely identified in industrialized countries, and the few reported cases of infection were usually in someone who had recently traveled to an endemic region. In the past few years this pattern has changed, as cases of endemic or autochthonous hepatitis E have been diagnosed with increasing frequency in individuals who have not traveled abroad….
Cases have been reported with increasing regularity throughout Western Europe, as well as in some Eastern European countries. [7]
The genotypes that coinfect humans and pigs may have originated in East Asia:
All but one genotype 4 sequence originated either from China or Japan…. [T]he genotype 3 sequences were divided into 3.1 and 3.2 clades … [A]lthough 87.5% of the clade 3.1 variants were from Asia and 60% of the clade 3.2 variants were from Europe (Table S1), these clades were found to have similar histories (Fig. 6). [1]
Historically, China and Japan did not raise cattle for food and pigs have been the major source of meat. Even today in southern China, pigs are often kept in the yards of homes, and close contact between pigs and humans facilitates zoonotic transmission.
At pig farms, Hepatitis E virus seems to spread readily. A Japanese study reported:
[O]ur estimates imply that more than 95% of pigs are infected before the age of 150 days. [3]
Presumably this is due to fecal-oral transmission among pigs in close quarters. At French farms, 65% of pigs were found to be hepatitis E infected at age 90 days. [4]
Transmission to Humans Via Pork
Can humans get infected by eating pork products? It now seems clear that the answer is yes.
A French study found that the genotype distribution of hepatitis E infecting humans is identical to the genotype distribution in pigs at slaughterhouses:
Frequent zoonotic transmission of hepatitis E virus (HEV) has been suspected, but data supporting the animal origin of autochthonous cases are still sparse. We assessed the genetic identity of HEV strains found in humans and swine during an 18-month period in France. HEV sequences identified in patients with autochthonous hepatitis E infection (n = 106) were compared with sequences amplified from swine livers collected in slaughterhouses (n = 43). Phylogenetic analysis showed the same proportions of subtypes 3f (73.8%), 3c (13.4%), and 3e (4.7%) in human and swine populations. Furthermore, similarity of >99% was found between HEV sequences of human and swine origins. These results indicate that consumption of some pork products, such as raw liver, is a major source of exposure for autochthonous HEV infection. [5]
As hepatitis E concentrates in the liver in both pigs and humans, swine livers were the natural place to test for hepatitis E presence, and probably the riskiest part of the pig to eat.
Further evidence that hepatitis E in pigs can infect humans was found in another French study. The researchers reasoned that sausage made from pig liver would be a likely vector for hepatitis E transmission to humans, especially a form of smoked pig liver sausage traditionally eaten raw – figatellu. Their findings:
Acute or recent HEV infection, defined by detection of anti-HEV immunoglobulin M antibodies and/or HEV RNA, was observed in 7 of 13 individuals who ate raw figatellu and 0 of 5 individuals who did not eat raw figatellu (P=.041). Moreover, HEV RNA of genotype 3 was recovered from 7 of 12 figatelli purchased in supermarkets, and statistically significant genetic links were found between these sequences and those recovered from patients who ate raw figatellu….
Our findings strongly support the hypothesis of HEV infection through ingestion of raw figatellu. [6]
The titer of hepatitis E viruses in the supermarket sausage reached as high as a million copies per slice. [6] This data suggests that a majority of figatellu in French supermarkets carries hepatitis E virus, and that a majority of people who eat figatellu acquire hepatitis E infections.
Contact with pigs can also lead to transmission; swine workers have an elevated prevalence of antibodies to HEV in the United States. [7]
Does Cooking Inactivate the Viruses?
What level of cooking is needed to inactivate the virus?
It is difficult to prove that any particular cooking or processing method renders HEV non-infectious:
How safe are these products? The question is difficult to answer because HEV grows poorly in cell culture, and in vivo testing of viability requires nonstandard laboratory animals—nonhuman primates or pigs for genotypes 3 and 4. [7]
Since scientists don’t have the funding or facilities to see if feeding cooked, cured, or smoked pork to primates or pigs gives them hepatitis E, they have no way of verifying that cooked, cured, or smoked pork is free of HEV.
In test tube experiments, HEV was still viable and infectious after cooking for 1 hour at 56°C, the temperature of rare to medium-cooked meat. [9] About 80% of viruses were inactivated after an hour at 60°C, and an hour at 70°C probably eliminates the viruses.
The implication is that thorough cooking would destroy HEV, but that some HEV will survive in rare to medium cooked pork, with liver likely having the greatest viral titer. [9] “However, much pork is consumed that has not had even that degree of cooking.” [7]
One way to reduce the risk of infection is to avoid the pig tissues that have the highest viral titers:
HEV can be found in the liver, blood, and intestinal tract, which are all consumed in one form or another and often together, such as in sausages. [7]
So: to avoid HEV infection, it’s best to avoid pork liver, intestines, or blood, or products made from them such as sausage; other cuts should be carefully rinsed of all blood and then cooked thoroughly to a temperature of at least 70°C. Simmering in near-boiling water for an hour should be sufficient.
The most dangerous pork product is likely to be sausage, which often uses pork liver meat, and traditionally uses pig intestines as the casing. It may also contain traces of pig blood. Pig blood pudding, a traditional Chinese dish, should also be avoided.
Links to Pork-Associated Liver Diseases
Hepatitis E was discovered as a cause of acute liver disease. But what about chronic diseases like alcoholic cirrhosis and liver cancer? Is there really evidence linking it to these diseases?
First, studies of organ-transplant recipients who contracted hepatitis E from their donors have shown that HEV seems to establish chronic infections in at least 58% of infected persons. [10] When anti-HEV antibodies exist, generally active viral RNA is present too. [12] So the virus is persistent.
Hepatitis B and C viruses are known causes of alcoholic liver cirrhosis. What about HEV? There have been few studies, but those that exist suggest it is likely:
- A child developed cirrhosis after a bone marrow transplant due to a swine-derived form of hepatitis E. [11]
- A Spanish study found a strong association between HEV and cirrhosis in people infected with HIV: “Liver cirrhosis was the only factor independently associated with the presence of anti-HEV, which was documented in 23% of patients with cirrhosis and 6% of patients without cirrhosis (P?=?0.002; odds ratio 5.77). HEV RNA was detected in three seropositive patients (14%), two of whom had liver cirrhosis.” [12]
- HEV seems to be a common cause of cirrhosis in Egypt. [13]
Hepatitis B and hepatitis C viruses are known causes of hepatocellular carcinoma. What about HEV? If there were few studies linking HEV to cirrhosis, there are even fewer investigating its relationship to HCC.
I did find one Chinese study showing that HEV infection greatly elevated the association of aflatoxin with HCC. (Aflatoxin, a fungal toxin that damages the liver, is a known risk factor for HCC.) [14]
Epidemiology is also suggestive. I mentioned earlier that the pork-transmitted genotypes of HEV have only recently appeared in the Americas. If HEV is responsible for alcoholic cirrhosis, hepatocellular carcinoma (HCC), or multiple sclerosis, then we should be seeing the incidence of those diseases increase. In fact, that is true for HCC:
In the U.S., incidence rates of HCC in both men and women have increased steadily during the past three decades. The reasons for this steady increase remain unknown. [15]
What About Multiple Sclerosis?
There have been no studies searching for a specific link between HEV and multiple sclerosis.
However, it may be worth reviewing what some mouse models tell us about the potential for a hepatitis virus to cause MS. MS is an infectious or autoimmune disease:
MS is felt to be most likely either due to an aberrant immune response or a pathogen, or possibly a combination of the two, and the animal models available reflect these two possible pathogeneses. [16]
Regular readers will know that I believe MS is infectious in origin. There are three animal models for MS. One of them (“experimental allergic encephalomyelitis” or EAE) involves immunizing mice with myelin or myelin proteins so that they develop antibodies to their own myelin; the other two involve infecting mice with viruses:
Two viruses, Theiler’s murine encephalomyelitis virus and murine hepatitis virus, are used to induce infectious models of the disease. [16]
The murine hepatitis virus (MHV) model is suggestive: it supports the idea that a virus that causes hepatitis may also cause MS. Some strains of MHV are neurotropic, infecting both the liver and central nervous system, and it is these that most readily produce an MS-like disease. [17]
If a hepatitis virus is causing MS in humans, we would expect MS patients to have high rates of liver disease. Indeed, there is a correlation.
MS patients are 3.7-fold more likely to have elevated ALT and 2.2-fold more likely to have elevated AST – both liver enzymes associated with liver disease. Also, elevated ALT and AST are associated with the more severe relapsing-remitting form of MS. [18]
A few perhaps insignificant links: Patients with systemic sclerosis, who are about 5-fold more likely to develop MS than others, are also at high risk for liver disease. [19] In the 1980s, doctors began observing MS patients with cases of primary biliary cirrhosis severe enough to require liver transplantation. [20]
Other Pig-Human Pathogens and MS
Pork can carry many pathogens; perhaps hepatitis E virus is not the MS-causing pathogen.
I don’t see obvious candidates however. Perhaps herpes viruses would be most likely. One of the human pathogens likely to be causal for MS is Epstein-Barr virus, also known as human herpes virus 4 (HHV-4). It causes mononucleosis but establishes persistent infections and is associated with a number of diseases, including lymphomas, MS, lupus, and rheumatoid arthritis.
Human herpes viruses may be able to establish infections in pigs. [21] And there are porcine herpes viruses that are closely related to Epstein-Barr virus. [22]
Conclusion
There is a strong association between pork consumption and liver cirrhosis mortality, liver cancer, and multiple sclerosis.
It seems likely that the association, if it is real, is mediated by a pathogen. The most likely pathogen in the case of the liver diseases is hepatitis E virus. In MS, the pathogen remains unknown, but is likely to be a virus.
Hepatitis E virus is not destroyed by casual cooking, smoking, or curing. It appears that meat must reach temperatures of 70ºC (160ºF) before viruses are inactivated; and it is possible that meat must remain at that temperature for some time, perhaps as long as an hour. Rare or medium cooked pork could contain active viruses.
Hepatitis E viruses are most abundant in liver, intestine, and blood. Pork products containing these parts, such as sausage, may be best avoided.
Meat from parts of the pig with low viral titers, such as pork ribs or pork bellies, are likely to be safe to eat as long as they are well cooked. Be sure to wash the meat of all blood before cooking, and to cook thoroughly.
Related Posts
Posts in this series:
- Pork: Did Leviticus 11:7 Have It Right?, Feb 8, 2012
- The Trouble with Pork, Part 2, Feb 15, 2012
- The Trouble With Pork, Part 3: Pathogens, Feb 22, 2012.
References
[1] Purdy MA, Khudyakov YE. Evolutionary history and population dynamics of hepatitis E virus. PLoS One. 2010 Dec 17;5(12):e14376. http://pmid.us/21203540.
[2] Purdy MA, Khudyakov YE. The molecular epidemiology of hepatitis E virus infection. Virus Res. 2011 Oct;161(1):31-9. http://pmid.us/21600939.
[3] Satou K, Nishiura H. Transmission dynamics of hepatitis E among swine: potential impact upon human infection. BMC Vet Res. 2007 May 10;3:9. http://pmid.us/17493260.
[4] Kaba M et al. Frequent transmission of hepatitis E virus among piglets in farms in Southern France. J Med Virol. 2009 Oct;81(10):1750-9. http://pmid.us/19697419.
[5] Bouquet J et al. Close similarity between sequences of hepatitis E virus recovered from humans and swine, France, 2008-2009. Emerg Infect Dis. 2011 Nov;17(11):2018-25. http://pmid.us/22099089.
[6] Colson P et al. Pig liver sausage as a source of hepatitis E virus transmission to humans. J Infect Dis. 2010 Sep 15;202(6):825-34. http://pmid.us/20695796.
[7] Purcell RH, Emerson SU. Hidden danger: the raw facts about hepatitis E virus. J Infect Dis. 2010 Sep 15;202(6):819-21. http://pmid.us/20695795.
[8] Purcell RH, Emerson SU. Hepatitis E: an emerging awareness of an old disease. J Hepatol. 2008 Mar;48(3):494-503. http://pmid.us/18192058.
[9] Emerson SU et al. Thermal stability of hepatitis E virus. J Infect Dis. 2005 Sep 1;192(5):930-3. http://pmid.us/16088844.
[10] Legrand-Abravanel F et al. Characteristics of autochthonous hepatitis E virus infection in solid-organ transplant recipients in France. J Infect Dis. 2010 Sep 15;202(6):835-44. http://pmid.us/20695798.
[11] Halac U et al. Cirrhosis due to Chronic Hepatitis E Infection in a Child Post-Bone Marrow Transplant. J Pediatr. 2012 Feb 15. [Epub ahead of print] http://pmid.us/22341950.
[12] Jardi R et al. HIV, HEV and cirrhosis: evidence of a possible link from eastern Spain. HIV Med. 2012 Jan 18. http://pmid.us/22257075.
[13] El Sayed Zaki M, Othman W. Role of hepatitis E infection in acute on chronic liver failure in Egyptian patients. Liver Int. 2011 Aug;31(7):1001-5. http://pmid.us/21733089.
[14] Tao P et al. Associated factors in modulating aflatoxin B1-albumin adduct level in three Chinese populations. Dig Dis Sci. 2005 Mar;50(3):525-32. http://pmid.us/15810636.
[15] Yuan JM et al. Synergism of alcohol, diabetes, and viral hepatitis on the risk of hepatocellular carcinoma in blacks and whites in the U.S. Cancer. 2004 Sep 1;101(5):1009-17. http://pmid.us/15329910.
[16] Pachner AR. Experimental models of multiple sclerosis. Curr Opin Neurol. 2011 Jun;24(3):291-9. http://pmid.us/21519255.
[17] Carbajal KS et al. Surgical transplantation of mouse neural stem cells into the spinal cords of mice infected with neurotropic mouse hepatitis virus. J Vis Exp. 2011 Jul 10;(53). http://pmid.us/21775959.
[18] Tremlett H et al. Liver test abnormalities in multiple sclerosis: findings from placebo-treated patients. Neurology. 2006 Oct 10;67(7):1291-3. http://pmid.us/17030771.
[19] Robinson D Jr et al. Systemic sclerosis prevalence and comorbidities in the US, 2001-2002. Curr Med Res Opin. 2008 Apr;24(4):1157-66. http://pmid.us/18430269.
[20] A patient with primary biliary cirrhosis and multiple sclerosis. Am J Med. 1992 Apr;92(4):433-6. http://pmid.us/1558090.
[21] Kim JH et al. Infection of porcine cells with human herpesviruses. Transplant Proc. 2010 Jul-Aug;42(6):2134-7. http://pmid.us/20692426.
[22] Doucette K et al. Gene expression of porcine lymphotrophic herpesvirus-1 in miniature Swine with posttransplant lymphoproliferative disorder. Transplantation. 2007 Jan 15;83(1):87-90. http://pmid.us/17220799.
via this link:
Excellent detective work and research. Food, *ahem*, for thought.
For the hundreth time I’m in awe of your analysis, good show! I always wonder about non-cooking-related methods of combating pathogens like spices and marinades, they definitely help deal with general pathogens but I wouldn’t bet on it unless I could find something definitive. I have been marinading all of my meat in wine and spice, because I’m also cooking at low temperatures, but when I have my occasional pork I’ll be sure to burn the little guys relentlessly. A little more carcinogen<hep E.
Oops, the greater-than sign should eat the carcinogens, not the hep E!
I just got back from a trip to the bar down the street. Whole 22 has ended, Jagermeister and 7 supplements or so are in my belly! Wahoo!
Fantastic job. I loved reading this mini-series. Best part though? Bacon comes off as alright hahaha.
Interesting anaylsis. I am wondering about your recommendation to cook with pig lard. Can we assume that lard is free from these pathogens?
When I read part 1 and part 2, you had me searching the internet for answers and bam, you came out with part 3! Thanks for the read….I wrote in the other post, if we buy bacon, should we go uncured/cured route and should we avoid the preservatives like nitrates and nitrites
Thanks again for all your hard work.
OK, what do we do if we have consumed a lot of pork in the past? I have had a lot of sausage in Europe, including Frane. Can we be tested for hepatitis E?
Hi, Paul —
Great series; thank you! I covered part 1 last week, and am working on a new episode of Latest in Paleo tonight, with parts 2 and 3 included…should be published tomorrow (Episode 52).
Although Hep E is not mediated by cooking, curing, or smoking, there still remains a lesser correlation with disease and processed pork. What am I missing?
Hi tanabear,
I would recommend that the lard be cooked also. It won’t have much in the way of viruses, but can have some.
Hi Jeremy,
Since there’s no treatment for hepatitis E, just try to live well from here and don’t worry about it.
Hi Angelo,
Curing and smoking reduces viral numbers but doesn’t eliminate them, so processed pork may be half as risky, but is still risky. However, bacon, which comes from pork bellies, is much less risky than sausage, which comes from riskier offal meats.
Wow. Tour de force. Hats off to you, Paul.
I’ll be taking my pork as carnitas next time. Long time cooking at near-boiling temperatures = lots of dead virii.
As an aside, the number of similarities between pigs and humans is truly amazing. Organ compatibility, skin appearance and texture (get pork belly with the skin on and you’ll see what I mean — especially if you get a slab with nipples!), fat composition, we even supposedly taste like pork!
Very strong analysis Paul. This sort of thing is the reason I keep coming back to your site. Thank you!
Andrea
I freeze my pork belly strips (which kills any worms), then cook them well before eating them.
I believe that worrying about every food & drink causes more harm (through chronically-raised cortisol) than the actual food & drink!
The alternative pork-free sausage: http://en.wikipedia.org/wiki/Merguez
Btw, pork sausages (like Nürnberger: http://en.wikipedia.org/wiki/Bratwurst) with small diameters are made with mutton’s intestine and no offal (just muscle meat). They should be safe.
Have been raising my own grassfed beef for years. The reason we’ve not done pig is we did not want to deal with escapees. Would there be a safe way to raise pork. Our land is pretty well isolated.
Would freezing work, as someone said above? In a huge fan of chorizo (a Spanish sausage). It’d be great to know freez
ing would make it safer.
Hi Alain,
Freezing can kill some worms but bacteria and viruses will survive. They need to be cooked.
Hi Richard,
I don’t know if it’s possible to raise disease-free pigs, but having an isolated farm and a natural environment would be a great start. The key thing is that they’re not confined in a way that they’re eating their own feces.
Hi Paul:
Nice work! So, what about the other aspects of Leviticus: shellfish? Some are saying stay away from shrimp.
If there is no treatment for Hep E what advice would you give someone with MS? Is there a specific way to eat to discourage the virus to proliferate? I mean besides PHD, of course. Lower carb, higher carb, supplements? You have given me advice before (much appreciated) so you don’t have to reiterate that but do you have any new thoughts on the subject? Do you still feel antibiotic treatment is the way to go?
Always appreciate your thorough analysis Paul! I can’t stand to do crossword puzzles so I use your blog as a way to keep my mind sharp.
Hi Paul
I have read your book wonderfull, but I do have problem with eating meat. I do not like the taste of it, actually I was vegan for 5 years now I eat fish mainly fresh organic salmon and eggs, raw goat or sheep? products, but I do have problem to eat meat and organs meat too. I can not stnd their smell taste it makes me trowing up. Please help me, can I achieve good health only with fish and eggs??? I do feel very very good I have lots of energy I just wanted to include meat and liver as you recomend. But for me it is easier to eat 2 sweet potato then just one and have pieces of meat. I am skinny and have no problem with starches like sweet potato. Thanks a lot for help
Thanks for this great and important article.
After the second part i started to search the internet and came out with the same candidate: HEV
Did you know that there is a possiple common mechanism for liver cirrhosis and MS? Subacut infection with hepatitis virus triggers leukotoxins in both cases …
Sorry, I made a mistake, I meant “Lymphotoxin” a protein that is produced by Th1 type T-cells …
It sounds as though I would know if I had hepatitis E: “It generally produces an acute disease that lasts for several weeks; most victims recover with few symptoms, but in a few this acute illness progresses into a severe liver disease that can be fatal. ” I have eaten pork, sausage, and bacon over the years but have never had the kind of symptoms you describe. Does this mean that I have not been infected with hepatitis E?
Good series Paul!
It seems with all meat that we’re caught between being told to cook with lower temperatures to lessen AGES and then higher temps to kill pathogens.
Pigs being similar to humans is eery and strange. In evolutionary terms, why does the pig have some similariies to us seemingly more than the monkeys? It just seems out of place from a four legged animal is all.
So let’s see here. We have freeze to kill worms, cook long time at 170 F to kill pathogens, from Price group: soak in vinegar, smoking it may be bad, nitrates are questionable, fresh and sausages bad, …pork’s a mess! I might eliminate it to avoid the hassle.
@ Sam
Check your zinc status.
I have hear that low zinc can cause you to have an aversion to meat.
Being vegan depletes zinc.
Thanks a lot
I take the higest quality zinc supplement on the market so I do not think it is low zinc. All my life life I have battle with meat I do not like it but I appreciate your help. With fish I do not have problem but meat like beef or lamb I can taste it. The worst is with organ meats for me
So there is no test for HEP E? I’ve definitely had my share of pork blood cake in Taiwan and pork liver pate in Romania and pork sausage in Germany. yikes….
Paul
Absolutely excellent.
I’ve wondered about Jewish kosher laws and it’s relevance…..
Or “halal” for that matter.
Thank you for your work on this but I am bit saddened as I will now taper my bacon consumption.
Marc
In my 20s I became very ill and now have a neurological condition (symptoms like MS). For many years it was thought to be syringomyelia. Recently, I received a new diagnosis of Devic’s (neuromyelitis optica) disease. Whilst the doctors have scratched their heads I have always been convinced that I contracted a viral infection. One minute I was well, the next; non-stop hiccups for two weeks, followed by vomiting, severe head pain, resulting in loss of co-ordination and eventual paralysis from the neck down.
Paul, you have said enough to convince me not to eat any pork product. Near boiling pork for an hour doesn’t make good eating in my opinion. I’ll miss crackling but that’s it.
Some people do smell like pork but I’m wondering how people know humans taste similar to pork.
Great series.
great… i most certainly have Hep E! to be honest, i’m not going to stay up nights worrying about it, but i’ve eaten pork liver quite often from mexican food places here in LA. it’s delicious in tacos. i’ve eaten it so man times! oh well. if the thunder don’t get you, then the lightning will…
@ Sarah H:
Keep up your purine intake. Uric acid levels are inversely related to relapses in MS patients; the foods that cause gout are GOOD for people with MS- or, at least, people with MS that are suffering attacks have very low levels of uric acid, and those who suffer from gout don’t overlap with those that have MS. It’s a remarkably sharp difference in the two groups.
Secondly, for MS- take your vitamin D. Sunlight is not enough. One study showed that 14,000 IU/day cut down dramatically on relapses. Now, that’s a lot; ideally, you’d optimize your levels (50-60 ng/mL), but somewhere between 5,000 and 10,000 IU/day would be safe and probably stave off minor infections (cold, influenza) that are liable to promote relapses.
Good luck.
Great series, Paul!
Do you think that there is any danger of disease transmission through Armour thyroid (desiccated thyroid extract from pork)? Armour has been working well for me, but this article has given me some second thoughts!
Great work Paul, and obviously we need to know more about Hep E.
HCV and HBV are easy to kill and HCV is probably impossible to catch from food. Sunlight, detergent, alcohol kill most viruses. It’s possible that osmolytic pressure from salt curing also kills them, I’ll have to look into that.
Most blood-borne viruses cannot persist for long outside the body, but airborne and soilborne viruses can be hardier.
In N.Z. most pork is now imported from China.
If pork is so close to human tissue that transplantation and injection of porcine insulin are safe, then it is also possible that some pork products are immunosupressive.
A mechanism linking Hep E to MS:
in the case of Hep C, elevated levels of interferon in response to chonic infection sensitize gut cells to gluten, and there is an increased rate of coeliac disease, in fact in one study gluten-related antibodies were highly predictive of HCV infection.
Coeliac disease and non-coeliac gluten sensitivity are known risk factors for MS.
This mechanism may also sensitize the gut to other food allergens.
Noooo! Please don’t take sausages away…
Osmotic pressure from salt kills bacteria: but protein-coated viruses may be resistant?
This study guide lists all methods of antimicrobial sterilization: http://faculty.ccbcmd.edu/courses/bio141/labmanua/lab19/lab19.html
OSMOTIC PRESSURE
Microorganisms, in their natural environments, are constantly faced with alterations in osmotic pressure. Water tends to flow through semipermeable membranes, such as the cytoplasmic membrane of microorganisms, towards the side with a higher concentration of dissolved materials (solute). In other words, water moves from greater water (lower solute) concentration to lesser water (greater solute) concentration.
When the concentration of dissolved materials or solute is higher inside the cell than it is outside, the cell is said to be in a hypotonic environment and water will flow into the cell (Fig. 1). The rigid cell walls of bacteria and fungi, however, prevent bursting or plasmoptysis. If the concentration of solute is the same both inside and outside the cell, the cell is said to be in an isotonic environment (Fig. 2). Water flows equally in and out of the cell. Hypotonic and isotonic environments are not usually harmful to microorganisms. However, if the concentration of dissolved materials or solute is higher outside of the cell than inside, then the cell is in a hypertonic environment (Fig. 3). Under this condition, water flows out of the cell, resulting in shrinkage of the cytoplasmic membrane or plasmolysis. Under such conditions, the cell becomes dehydrated and its growth is inhibited.
The canning of jams or preserves with a high sugar concentration inhibits bacterial growth through hypertonicity. The same effect is obtained by salt-curing meats or placing foods in a salt brine. This static action of osmotic pressure thus prevents bacterial decomposition of the food. Molds, on the other hand, are more tolerant of hypertonicity. Foods, such as those mentioned above, tend to become overgrown with molds unless they are first sealed to exclude oxygen. (Molds are aerobic.)
This paper suggests it is possible:
Osmotic Shock and the Strength of Viral Capsids
Amado Cordova*, Markus Deserno*, 1, , , William M. Gelbart* and Avinoam Ben-Shaul
Abstract
Osmotic shock is a familiar means for rupturing viral capsids and exposing their genomes intact. The necessary conditions for providing this shock involve incubation in high-concentration salt solutions, and lower permeability of the capsids to salt ions than to water molecules. We discuss here how values of the capsid strength can be inferred from calculations of the osmotic pressure differences associated with measured values of the critical concentration of incubation solution.
Agatha,
I hear ya. Maybe you could try to find grass-fed beef sausages? That is what I buy from a local farm. They make spicy, breakfast, and mild. Yum! 🙂
CJ,
thanks so much for the information. I am very careful to remember my Vit D but I did not know about the uric acid connection. I will definitely research that!
good stuff.
How much does gut function play in this? Is hydrochloric acid, bile, enzymes, etc. effective at deactivating viruses like it does bacteria, and the toxins that can come from the viruses? Proteases are effective at digesting the casing on viruses.
Think about all of the people on acid suppressing drugs for heartburn, which really seems to be due to too little acid, and those without gall bladders. I would think most Americans have poor digestive function. This has to play some role with increasing risk for infection.
It just seems like optimizing gut function by making sure there is sufficient acid in the stomach, having a healthy gall bladder or taking bile salts if no GB is present, and a healthy pancreas for enzyme production would be quite protective too.
So no more black pudding? There’ll be tears!
Paul-
Excellent and useful posts. I am enjoying the diet very much and feeling good.
When you write “If you’re going to eat a lot of pork, there are real benefits to finding a source of naturally raised pigs fed a healthy diet”, what type of diet are you suggesting?
I plan to ask the farmers at the market and my butcher who sources only local, humanely-raised meats, but what am I looking for?
Thank you.
Still wondering if pork is good or bad but here is an interesting link.Seems countries with high pork consumption are ones with good health statistics.
http://www.nationmaster.com/graph/foo_por_con_per_cap-food-pork-consumption-per-capita
Pork will kill you. It’s just a matter of how long it takes. Looks like God was right. Do paleo folks believe in God? Even if you don’t, pork will still kill you.
Why take the chance with pork. There are lots of clean healthy meats to choose from.
Scandinavian countries (and I grew up in one…:-0 )seem to have a high incidence of MS, as well as traditional recipes such as blood pudding, that incorporate pig blood. Oh well…I, too am now concerned about porcine thyroid- based medications…any thoughts?
Thanks for yet another a great and engaging, as well as tremendously informative whodunnit- series of blogs!
For sure pork is one of the worst foods you can ever eat. “We are what we eat”. Pigs eat anything even their own piglets! Pork has too much fat and cholesterol which is not healthy for humans.
Thanks for the post
Hi Franco,
Yes, beef and lamb sausage are good substitutes!
Hi Steve,
I’m pro-shellfish until I learn some compelling reason otherwise. They do carry pathogenic bacteria in their digestive tracts, including Vibrio cholerae. But keeping them on ice from the time they’re caught, and cooking them, solves that. I don’t think the ancient Israelites had ice.
Hi Sara,
People with MS should eat well and nourish their immune system and nervous system, first. Intermittent fasting with a bit of coconut oil helps the nervous system. MS patients often have bacterial co-infections, so antibiotics usually help. Doxycycline is good because it’s minimally disruptive to gut flora; see http://cpnhelp.org for some antibiotic protocols that often help in MS. Vitamin D/A/K2 optimization is crucial, as is NAC/glutathione/selenium support.
While MS is difficult to entirely cure, you can greatly improve nerve and brain function and prevent disease progression.
Hi Sam,
Yes, you can achieve good health with just fish and eggs.
Hi Martina,
Thanks, I didn’t know about the lymphotoxins, I’ll have to investigate.
Hi Andrea,
I think the obvious acute disease comes more often from feces-infected water than from pork. A small dose of the virus may not produce much in the way of acute symptoms. Even if they do, you might think it was a cold or some such. While it’s good that you’ve never had an obvious acute disease, it doesn’t guarantee that you’ve never been infected.
Hi Jaybird,
Yes, it is a conundrum. But not an insoluble one.
To kill pathogens you need to get the internal meat temperature above 70 C for an hour; that’s easily achieved by cooking in water at 100 C for an hour or so. To form toxins from cooking you need temperatures near 200 C. So gentle, slow cooking methods like cooking in water (stews, soups, curries) will work great.
Hi Eric,
You can probably get an antibody seropositivity test, and they can look at liver enzymes. Ask your doctor.
Hi Pauline,
Sorry to hear about your illness. I believe that autoimmune conditions are always caused by underlying infections, and I would agree with you that it may well have been a viral infection in your case.
Best of luck.
Hi Danae,
I doubt there’s much risk from Armour thyroid, but to be honest I don’t have any basis for evaluating how great the risk might be.
Hi CJ, George,
Thanks for the information!
Hi phooey,
Definitely gut function will play a big role in determining how likely an infection is. But even those with a healthy gut aren’t totally immune.
Hi Hilary,
A bad diet for pigs is (a) mainly composed of grain and vegetable oils like soybean oil – these will create a high omega-6 level and an unhealthy pig; and (b) fed in unsanitary conditions so that feces can mix with the feed, spreading germs among the pigs.
Natural foods with lower caloric density and lower omega-6 levels, as with human diets are much healthier; as are conditions in which they have room to move and are not exposed to feces too much.
Hi Wolfstriked,
Yes, I noticed that correlation too. But it works for all animal foods, in general richer countries buy more animal foods and are healthier. Also pork is popular in Asia where they tend to eat rice and coconut milk and seafood.
Blood Sausage is one of the best tasting things on the planet.. Worth getting sick for? Possibly!
thanks.
i wonder if that’s why traditionally, we marinade pork with wine, & some acid. also it is well cooked
(we don’t eat rare or median pork)
the “blood cake” in Taiwan is a peasant food. it is steamed & well cooked (as far as i know). so it should probably be ok.
although sometimes it’s deep fried these days.
regards,