The Dangers of Foodborne Pathogens

**Michael Greger** (0:00)
I'm often asked my opinion about the cause or treatment of some medical condition, but the question to instead ask is what does the science say? What does the best available balance of evidence published in the peer-reviewed medical literature have to say right now? Welcome to the Nutrition Facts Podcast. I'm your host, Dr. Michael Greger. We put a lot of thought into eating what's best for us, so the last thing we need is an inadvertent pathogen hiding in our alfalfa sprouts. Here is our first story. According to the US. Centers for Disease Control and Prevention, we should cook alfalfa sprouts, because eating raw sprouts can lead to salmonella food poisoning. It's especially important not to eat raw sprouts if you are particularly old or young, immunosuppressed or pregnant. How serious of an issue is this? Over the last few decades, at least 2,700 Americans have been sickened by sprouts. That's more than 100 people a year.
Of course, during that same time, more than 100,000 Americans were being food poisoned by eggs contaminated with salmonella. Indeed, salmonella in eggs is a national epidemic in the United States, and salmonella is a gift that can keep on giving trickling arthritis sometimes, which in rare cases can last a lifetime. So no sprouts on that sandwich, but do you hear the CDC saying no eggs, even though they cause a thousand times more illness? No, but the CDC does say no raw or runny eggs, no soft-boiled eggs, no sunny-side up. Even the egg industry itself admits that over-easy poached sunny-side up or soft-boiled eggs can't be considered safe. No wonder eggs are sickening 100,000 Americans a year. Eggs have to be cooked hard to kill off their bacteria. Similarly, if we boiled our sprouts, they'd be safe too, but no one wants to do that either. The largest national sampling was from about a decade ago, when the Food and Drug Administration tested sprouts in sprout facilities from all over the United States. The agency found that 1% of alfalfa sprout samples were affected, and even worse, 10% of alfalfa sprout seed samples were too. So that's why you can't just grow them yourself. The bacteria can get in the nooks and crannies of the alfalfa seed itself. The majority of outbreaks have been linked to alfalfa, but there's also been outbreaks tied to clover sprouts, mung bean sprouts, which are more like typical bean sprouts, and sprouted chia. The National FDA survey did not find any salmonella and mung bean sprouts, but did find that about 2% were contaminated with listeria, which can be a particularly devastating infection for pregnant women. What about the deadly jack-in-the-box E coli 0157H7? How often can it be found in retail ground beef, sprouts, and mushrooms? Well, none were found in any mushrooms, but one out of every 90 or so samples of burger meat was contaminated, and about one out of just 70 sprout containers. But what if you really like raw sprouts? Instead of alfalfa, use broccoli sprouts. They have smooth seeds, and after testing the equivalent of about 5 million packages, less than 1,000 bulk samples turned up positive. That may have been contamination from other types of sprouts. Broccoli sprouts are easy and cheap to make on your own kitchen counter, like I do for pennies of serving. I have more than that dozen videos on all the amazing things that sulforaphane and broccoli sprouts can do, everything from treating autism spectrum disorder to detoxifying the effects of air pollution. They have also been shown to combat different types of cancer cells, and you can pretty much only get this natural immune system enhancer in cruciferous vegetables like broccoli, broccoli sprouts, and I guess if you're really desperate, broccoli beer. Did you know that tainted chicken may result in more than a million urinary tract infections in American women every year? Here's the story. In my video on antibiotic-resistant genes, I explored how more were found in the guts of those who eat meat, dairy, and eggs than those who eat completely plant-based. But does the transfer of bacteria from animal foods in the human gut result in differences in actual clinical outcomes? Other than food poisoning, of course. Food-borne bacteria is sick in about 350 million people every year. Most of that can be traced to meat, dairy products, and eggs. Besides food poisoning, though, what about extra intestinal infections, infections outside the digestive tract? For example, due to pathogenic and antibiotic-resistant E coli from retail chicken breast. Infections where, though? The urinary tract. There's a type of E coli called ST131, which is a food-borne uropathogen, meaning it causes urinary tract infections, most of which are just bladder infections, which typically amount to a little more than a painful annoyance, but can become invasive and spread up into the kidneys and invade the bloodstream and end your life. E coli ST131 emerged explosively in the last 20 years or so to become the most important multidrug-resistant uropathogen in circulation today. Urinary tract infections are caused principally by ascending E coli infection via an intestine-stool urethra route, meaning these E coli that cause UTIs, called extraintestinal pathogenic E coli, or expec bacteria, start out in the colon, make it to the anus, and then make their way up into the urethra, then into your bladder. How do they get into your intestines in the first place? That's where the chicken comes in. The role of poultry meat can be to introduce the expec bacteria, allowing it to colonize the rectums of consumers lying in wait until an opportunity to cause infection presents itself. For example, thrusting from sexual intercourse can introduce the bacteria into the urethra. The time lag between human expec acquisition in the intestine and the bladder infection has been the fundamental challenge linking the two, but we now have strong evidence that a substantial portion of the ST131 strains infecting humans originate from poultry. But they couldn't tell whether any single infection arose from direct exposure to contaminated poultry, or indirectly from chicken meat from human-to-human transmission from say a partner who ate some contaminated poultry. What percentage of human UTIs arise from poultry? Researchers analyzed E coli isolates from urine samples from patients with suspected UTIs, and compared them to the bacteria on retail meat samples in the same region using DNA fingerprinting techniques. They found that about a fifth of E coli isolates from suspected cases of UTIs belonged to types found in local retail poultry. 21% might not sound like a lot, but E coli UTIs are one of the most common infectious diseases in the United States, affecting approximately 7 million women. So contaminated chicken may result in more than a million UTIs in American women every year. This may explain why women infected with multi-drug resistant E coli reported more frequent chicken consumption, putting them at nearly four times the odds, though frequent consumption of pork was also a risk factor. Wait, is it found in pigs, too? Human expec, those extra intestinal E coli that cause UTIs, have also been identified on pig farms, in pigs, and in retail pork meat, albeit at considerably lower levels than in poultry or chicken meat. So chicken is riskiest, pork less so, and beef could be considered the safest from a UTI standpoint, since cattle don't appear to be a reservoir of these particular types of E coli. OK, well, if meat, including poultry and pork, is the major reservoir for these UTI bacteria, then vegetarians who avoid meat should theoretically suffer less exposure. However, no study thus far has examined whether vegetarian diets reduce the risk of UTIs until now. A prospective study on the risk of urinary tract infection in vegetarians versus non-vegetarians. Well, if around 20% are tied to retail chicken meat, no surprise that eating vegetarian is associated with around 20% lower risk of UTIs, particularly in women. And this association was independent of diseases and predisposing risk factors like hypertension, diabetes, and high cholesterol, meaning it's not just due to the fact that vegetarians had less diabetes or something. What about buying organic chicken? Bacteria swabbed from chicken labeled organic harbored less antibiotic-resistant bacteria, but no, no less likely to be contaminated with expec UTI bacteria. These findings suggest that retail chicken products in the United States, even if they're labeled organic, pose a potential health threat to consumers because they are contaminated with extensively antibiotic-resistant E coli, including the ones that cause UTIs. To date, only the jack-in-the-box E coli, like 0157H7, are considered food adulterants, meaning it's not legal to knowingly sell contaminated meat. Why don't they do the same with the expec bugs? Now that there's such strong evidence they're infecting so many women? Well, in a survey of retail chicken breasts collected widely across the United States, 14.3% of the E coli they found appeared to be expec. Given that E coli can be found in about 90% of retail turkey and chicken products, that would mean the industry would have to dump literally billions of pounds of chicken breasts every year. Finally, today we look at how organic produce may present less of a food safety risk, given the potential contamination of pesticides with fecal pathogens. Wait, what? Check it out. Although the most serious causes of food poisoning, like salmonella, come mostly from animal products, for example, most foodborne-related deaths were attributed to poultry, millions of Americans are sickened by produce every year thanks to noroviruses. Noroviruses can be spread person to person via the fecal-oral route or the ingestion of aerosolized vomit, which may explain most norovirus food outbreaks, but a substantial proportion remain unexplained. How else could fecal viruses get on our fruits and veggies? The pesticide industry may be spraying them on. The water that's used to spray pesticides on crops may just be dredged up from ponds contaminated with fecal pathogens. The application of pesticides may therefore not only be a chemical hazard, but also a microbiological hazard for public health. So, what's their solution? Add more chemicals. The inclusion of antiviral substances in reconstituted pesticides may be appropriate to reduce the virological health risk posed by the application of pesticides. Or we could just choose organic. Either way, though, we should always wash all fruits and veggies under running water, as one solution to pollution is dilution.