 When you make sauerkraut at home, you don't have to add any kind of starter bacteria to get it to ferment, because the lactic acid-producing bacteria are already present on the cabbage leaves themselves out in the field. This suggests raw fruits and vegetables may not only be a source of prebiotics, fiber, but also a source of novel probiotics. Researchers have since worked on characterizing these bacterial communities and found two interesting things. First, that the communities on each produce type were significantly distinct from one another. So the tree fruits harbor different bacteria than veggies on the ground, and grapes and mushrooms seem to be off in their own little world. So if indeed these bugs turn out to be good for us, that would underscore the importance of eating not just a greater quantity, but greater variety of fruits and veggies every day. And second, they found that there were significant differences in microbial community composition between conventional and organic produce. This highlights the potential for differences in the bacteria between conventionally and organically farmed produce items to impact human health, but we don't know in what direction. They certainly found different bacteria on organic versus conventional, but we don't know enough about fruit and veggie bugs to make a determination as to which bacterial communities are healthier. What about probiotic supplements? I've talked about the potential benefits, but there appears to be publication bias in the scientific literature about probiotics. This is something you see a lot with drug companies, where the sponsor, the supplement company paying for their own probiotic research, may not report negative results, not publish it, as if the study never happened. And so then we doctors just see the positive studies. Using fancy statistical techniques, they estimated that as many as 20 unflattering studies were simply MIA. And even in the studies that were published, even when the authors were directly sponsored by like some yogurt company, the conflicts of interest were very commonly not reported. There's also been concerns about safety. A review for the government's Agency for Healthcare Research and Quality concluded that there's a lack of assessment in systematic reporting of adverse events in probiotic intervention studies, so while the available evidence in randomized controlled trials does not indicate an increased risk for the general public, the current literature is not well equipped to answer questions on the safety of probiotics with confidence. This is the study that freaked people out a bit. Acupancreatitis. Sudden inflammation of the pancreas is on the rise, which can become life-threatening in some cases, as bacteria break through our gut barrier and infect our internal organs. Antibiotics don't seem to work, so how about probiotics seem to work on rats if you cause inflammation by cutting them open and mechanically damaging their pancreas? Not only do probiotics show strong evidence for efficacy, but there were no indications of harmful effects. So half the people with pancreatitis got probiotics, half got sugar pills, and within 10 days the mortality rates shot up in the probiotics group compared to placebo. More than twice as many people died on the probiotics. Thus probiotics for acute pancreatitis is probably not a good idea, but further probiotics can no longer be considered to be just completely harmless. The researchers were criticized for not telling patients, not cautioning patients about the risk before signing up for the study. The study subjects were told probiotics had a long history of safe use with no known side effects. In response to the criticism, the researchers replied, there were no side effects until their study.