What You Need to Know About Foodborne Illness – Part 1

It’s a regular headline: “# of People Sickened by Contaminated Food.” Most recently, it was a case of imported cucumbers with salmonella (one of the most common and serious foodborne pathogens) that resulted in at least 341 people ill and two dead across 30 states. It’s difficult when public service information shifts us toward viewing our food with a nervous eye. The CDC estimates approximately 48 million people get sick from foodborne illness each year. Of those, 128,000 are hospitalized and about 3000 die.

So, what do we do with this information? At best, we decide to learn more about the bigger picture of our modern food supply. At its worst, we go to the place of panic, anxiety-ridden that every single item we bring home must be sanitized or cooked within an inch of its life. Some people even take the news as confirmation that fresh (real) food as “too dangerous” and join the brigade that believes/sells processed, packaged and otherwise adulterated food products as the only “safe options.” Never mind that fast food and processed products have been the subject of these events in the past…

It’s the kind of news that can easily stoke the media fear machine that encourages a perpetual state of anger, anxiety and frenzy. And let’s face it, a contamination event makes for more interesting news fodder than the ongoing, same-old, same-old story about rampant obesity and related lifestyle disease.

Nonetheless, I think rational people could say that part of speaking back to overzealous fear can be taking reasonable precautions that don’t cost much in terms of time or effort for the enhanced safety they afford. Realistic peace of mind isn’t about the eradication of all risk but 1) the understanding of common pathogens’ sources and behaviors and 2) application of sound strategies that minimize it. Let’s take apart that first point in part one today.

I don’t know very many people who haven’t at some point been sick with food poisoning. Most of us recall the misery but ultimately poo-poo the bigger ramifications because we just didn’t experience them personally. While most people get a few days of diarrhea or vomiting, others may deal with the costs of hospitalization or the burden of ongoing complications (not to mention the ultimate price those 3000 people a year pay).

Longer term repercussions of these pathogens include conditions like reactive or chronic arthritis, urinary tract issues and eye damage from salmonella or shigella, Guillain-Barre syndrome or ulcerative colitis from campylobacter, kidney failure or diabetes from Escherichia coli or meningitis, mental retardation, seizures, paralysis, blindness or deafness from Listeria.

Researchers have identified more than 200 pathogens, which include bacteria, viruses, parasites and toxins, responsible for “food poisoning.” Three (salmonella, toxoplasma and listeria) are responsible for 75% of known food pathogen related deaths. Although estimates vary, it’s accepted that not even half of foodborne illness sources are ever found. Most of the identified causes we hear about (like the salmonella case) are bacteria based. Virus caused outbreaks are the least likely to be documented generally because of their often shorter duration and smaller scope (often caused by human food handlers rather than the food itself).

The truth is, food has always been a messy enterprise. Even under the most natural and unadulterated conditions, growing food in dirt is, well, dirty. Animals are creatures that are subject to the wear and tear of their food chain placement (e.g. parasites, diseases of their last carnivorous meal).

Today, however, we’re dealing with a shifted picture. Even just a few decades ago, food illness outbreaks looked considerably different. The infections you heard about more often were Staphylococcus or Clostridium. Illnesses were more likely from home preparation (maybe passed on at church picnics or holiday buffets).

In some regards, we might be safer from the higher risk dealings of bushmeat, but most of us purchase food from an agricultural system that can be its own hotbed of pathogenic disease. From the unnatural diets given to many livestock to the massive crowding of feedlot conditions to the cross-contamination of meat processing plants to the irrigation of produce fields with sewage-laced water, modern conditions – despite industry safety protocols – set us up for issues that can have a much more extended reach (as in 30 states’ worth).

With the uptick in eating out, we’ve also opened up whole new arenas of human handling and mass food processing risks as well. These days, however, 80% of foodborne illnesses come from somewhere other than home.

The next logical question seems to be what foods are the most risky. Oddly, meats are overseen by a different agency (USDA) than most other foods (FDA), but experts have been clear that the majority of food poisoning cases stem from meats – especially beef and poultry. Ground beef, in particular, can be risky because a single burger can contain parts from various parts of various cows, increasing the chance of contamination. Pathogens can originate through everything from livestock feedwater to unclean fields/lots to contaminated processing equipment.

Aside from meat, a consumer group, the Center for Science in the Public Interest has ranked the ten (non-meat) riskiest foods for foodborne pathogens that are regulated by the FDA. (PDF)

Leafy Greens

Greens are responsible for nearly 1/4 of non-meat food poisoning outbreaks. Sources of pathogens can be contaminated water, animal manure contact, industrial washing equipment contamination or other handling problems. E. coli and salmonella are the most common pathogens found in greens.


Eggs can be contaminated from chickens themselves, in which case the interior of the egg can harbor a pathogen like salmonella. Pathogens can also enter through microcracks or contaminate shells during processing.


Scombroid toxins are the biggest culprit here and is more common is fresh or raw tuna – particularly if left in warm temperatures too long. With these toxins, cooking won’t make a difference unfortunately.


Raw oysters can be a source of norovirus or, less often, vibrio (related to cholera). Contamination can be caused by poor handling or unclean water.


Salmonella is the top problem here, but listeria is a common pathogen also associated with potato related food poisoning. Food preparation and cross-contamination are probably the most common sources of pathogens.


Again, salmonella and listeria are respectively the most common pathogens implicated in this category. Pathogens can be a result of the multi-step processing of cheeses, although pasteurization has reduced contamination risk.

Ice Cream

Salmonella contamination from eggs or listeria contamination often from unclean equipment are the more common causes here.


Again, salmonella is the main culprit, but norovirus is another common pathogen found in tomato related outbreaks. Agricultural conditions is a major concern in tomato (as in other plant) contamination.


Sprout seeds themselves may be contaminated, but poor handling is a frequent cause as well. Salmonella and E. coli are the most common pathogens found in sprouts.


Berries, like other plants that are often eaten raw, can harbor a number of pathogens related to dirty field water or animal manure contact, but handling by infected agricultural workers can be an issue as well.

Now that we’ve looked more closely at the problem of food contamination itself, let me pick up the topic again next week as I look at strategies for avoiding foodborne illness. Thanks for reading, everyone. Let me know your thoughts, and have a great week.

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About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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31 thoughts on “What You Need to Know About Foodborne Illness – Part 1”

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  1. if you’re looking for a “deep dive” on this subject, check out the first volume of modernist cuisine.

  2. When I saw the graphic “Food Poisoning” I thought it was going to be about sugar.

  3. “but ultimately poo-poo the bigger ramifications”

    When I had food poisoning, it wasn’t just the bigger ramifications I poo-poo’d.

  4. Mark, thanks again for engaging your readers in a critical, but difficult topic. It’s important for people to understand the realities. In my former life, I was an upper level executive in both the Imported Foods and Drug Industries. I interacted regularly with Federal and State officials involved with Safety and Health, and the DEA. Trust me, the regulatory process and the self-monitoring procedures have never been sufficient to guarantee the safety of the public. It’s imperative that people understand how to protect themselves from contaminated foods as well as drugs.

    I look forward to reading your next post in this topic. Great stuff. Thanks for caring enough to write about it!

    Memo Stephens

  5. I’m really curious if the widespread use of antacids is affecting those numbers.

    1. … or if products like Kefir or other fermeted foods are protective.

  6. oh-oh, we’re on our own for a week. Good time to fast. There’s the quick and the dead, and I want to be quick.

    1. You could have some genetic mutation that means a week’s fast wipes your heart out? Or makes your body consume its own eyeballs or something? Yeah, I’m a sadist… 😛

  7. Some people seem to have cast-iron GI tracts. Nothing they eat ever bothers them. I’ve never been one of those people. I learned a long time ago that if it can’t be washed and/or cooked, then I don’t eat it. That doesn’t eliminate everything that could be a problem, of course, but it goes a long way. I’ve been sick with food-borne illness only once in the last 30 or so years.

  8. Mark, did you really just give space to something coming out of CSPI? Whether correct or not, they deserve no reference in credible conversation due to their activist history.

  9. Bad bugs are likely a factor in Grok’s short life span. I would imagine external wound infections were more common than systemic foodborne in the cause of death for early humans. Grok may not have known what a pathogen was but he likely had an acute sense of smell. Bad smell don’t eat. Those of us who ferment foods and practice the science of microbiology learn good smells from bad. Pedicoccus is why your dog’s feet smell like popcorn. The tradition of Halal meat processing in the faith of Mohammed most likely stems from historical health risk of consuming roadkill. This is a great topic and the FDA has a free ebook to download from one of the links above called the Bad Bug Book for more comprehensive information.

  10. “At its worst, we go to the place of panic, anxiety-ridden that every single item we bring home must be sanitized or cooked within an inch of its life.”

    And you follow this with everything a germ freak is going to panic about!
    But, not to worry… Part II next week…


    1. Yeah, I know. Good thing for me that I don’t freak out about this kind of stuff too much. Now a co-worker of mine, who gets a paper towel to open the office refrigerator, on the other hand….

      My first thoughts when I saw “let me pick up the topic again next week” were “Next week! Next week! We’ve got to wait a whole week?!? After being given all of the information above? Oh well. Good thing I don’t freak out about this kind of stuff.”

      1. You’ve made it this far, so the odds favour you’ll just about scrape through to next week… 😉

  11. In my various experience living and working in 2 different African countries food poisoning ended being something that I sort of looked forward to. upon arrival in those countries I was very overweight from SAD diet back in the US. In my travels I ate what my local friends ate, and I didn’t carry around hand sanitizer. We slaughtered sheep and goats and I drank the blood from the animal, and even one time ate a raw kidney fresh from the body(it was disgusting raw, but the heart and liver were delicious when we fried them up later). Funny enough, the times i got food Poisoning were from the western eateries in the nearby town. But the great part of food poisoning for me, was that after I got food poisoning, and only after, i started losing weight, and I’m not just talking from the immediate affects of vomiting and diarrhea, I would lose upwards of 40lbs in the next two months, and not even changing my diet. I have a personal theory which could be totally wrong, but that’s why it is a theory, that the food poisoning was able to clean out my gut biome, and then replenish it with the healthy bacteria once i wasn’t sick anymore and eating the more natural Kenyan/Botswana diets and living in an unsanitized environment. BEFORE i got sick i didn’t lose any weight because i still had the bad bacteria in my gut, but AFTER I was sick is when I was able to actually lose weight without a change to my diet. Of course, when I moved back to the US i gained all the weight back that I lost 🙁 And no, I didn’t have any worms or anything, I was always cleared by a doctor when I came back to the US

  12. For one thing, most of these illnesses can be avoided by simply making sure that you rinse off your leafy greens well, and scrub those vegetables that stand up to it (potatoes, carrots, etc.) under running water before you eat them.
    Also, many of these problems come with factory farming practices. If you can buy from smaller, more local sources, you will have less chance of these issues. Admittedly, not everyone has the time or space for gardening, or raising their own chickens, but if you do, your food will be safer for it.
    Still, all in all, our food supply is pretty safe. If you eat real foods, and thereby strengthen your immune system, you are less likely to get seriously ill from these microbes.

  13. I hope he talks more in part 2 about how supplementing with “friendly” bacteria, i.e. acidophilus, can help stave off food borne illness.

  14. There aren’t many nicer things than a good bout of Noro. Makes you feel so humble. And if someone else in the family starts it you know that it will come to you, too, in a few hours. Every §$%& time.

  15. I am so fascinated with everything to do with gut health, diet, bacteria etc lately. I have a few autoimmune conditions and new symptoms all to do with gut inflammation so I am reading everything you post with much interest and just wanted to say Hi and thanks.

  16. A few months ago my man, affectionately known as The General, scored us a pasture raised lamb. When he went to pick it up from the eccentric farmer, he found it was frozen in just two pieces. So they sawed it into chunks, which they then tossed into a couple of plastic boxes. By the time he got home, parts of the lamb were defrosting. I think I went into panic – all of my safe-food handling knowledge came to the fore, with images of food poisoning clamouring. ‘Good Lord, man, are you mad!’ (in Italian) sort of fell out of my mouth, and we automatically switched into production-chain mode, with me wrapping and bagging the lamb bits, and him running them down to the freezer. Seems we managed to stop the freeze-and-defrost cycle in it’s tracks, as we’re eating through the lamb, with no nasty side effects. But next time we’ll be better prepared!

  17. I got poisoned from raw oysters last year – very unpleasant, but fortunately I am healthy, got over it within a day. Talking to friends, several older friends of friends suffered ongoing complications from their raw oyster-poisoning bouts. As you get older and hear these stories, you certainly think more about food safety. I only eat fried oysters now.

  18. Wow, reading this really makes you skip a meal or two… Getting ill from eating raw or unverified food is one thing, but when the food is processed, verified and certified by FDA or USDA, what can you do? More solutions would be nice 🙂

    1. I never have stomach upsets from drinking raw grassfed goat milk from local farmers even when it turned a bit sour, the USDA certified organic grassfed pasteurized milk always creates bloating and 6hours of relentless farting. YMMV.

  19. I ended up getting food poisoning from raw oysters back in 2011. I had never been so sick in my life. I had long term effects that lasted months! Although I love raw oysters, I haven’t had the courage to eat them since.

  20. Most of the times you can get food poisoning from fish and eggs, but you can avoid this by making sure the food is fresh and washed properly. Things change when you are eating in a restaurant, because you don’t know too much about the ingredients.