 We have a lot of choices to make about our diet. Add to that doing the right thing when it comes to preventing or treating a chronic disease, fighting a virus, or losing weight, and suddenly our nutrition choices can seem almost overwhelming. Well, I'm here to help. Welcome to the Nutrition Facts Podcast. I'm your host, Dr. Michael Greger. More than 10,000 articles have been published on gluten in medical journals, intimidating even for me. Today we have a three-part series summarizing the best available science on gluten. In our first story, we look at how we might prevent the inflammation that occurs from gluten-free diets. Over the last decade or so, there's been a growing interest in the medical literature on plant-based eating beyond just exclusionary terms like vegetarian or vegan. Previous such studies were somewhat limited because they just split people up into either vegetarian or non-vegetarian, excluding some or all animal foods, but without taking into account the quality of plant foods. Vegans could be living off of that, French fries, Oreos, and Coca-Cola. Enter changes in plant-based diet quality in total and cause specific mortality. The first study to investigate the associations between changes in plant-based diet quality and subsequent risk of death. If you look at overall plant-based diet scores, the more you increase your intake of any plant foods and decrease your intake of any animal foods, the lower your risk of death appears to fall. But that's because people were adding healthy plant foods like fruits and vegetables. If you just look at people who ate more processed sugary junk over time, their mortality risk goes up. The clinical implications being the increasing intake of healthy plant foods and decreasing intake of not just animal foods, but also animal crackers could lower the future risk of premature death. Whereas just reducing the intake of carbs in general, cutting down not just refined carbs and sugars, but healthy, high carb foods like fruits and whole grains, is associated with increased overall mortality, which could correspond to years of your life being cut short, as well as the risk of dying specifically from heart disease, stroke, and cancer. Why are whole plant foods so good for us? Much of the benefit may be mediated by our microbiome. There are all sorts of things threatening our good gut bugs, like the overprescription of antibiotics. However, the only factor that has been empirically shown to be important is a diet low in microbiome-accessible carbohydrates. In other words, prebiotics like fiber and resistant starch only found one place in abundance, whole plant foods. We went from high-mac diets to big-mac diets and maybe suffering the consequences. The lack of dietary fiber, which is the main source of max in the diet, is negligibly low compared to how we evolved. Such a low-fiber diet provides insufficient food for our gut microbes, starving ourselves of all the wonderful things they produce for us. A low-fiber diet is a key driver of microbiome depletion, and this loss is implicated in the rampant increase of chronic diseases that now plague the modern world. We evolved getting perhaps 100 grams of fiber a day. Our gut bugs must have been in heaven. How do you even get close to that? A cup of fruit may only have about 3 grams. A cup of vegetables, 5 grams. Why so little? Because fruits and vegetables are like 80 to 90% water. One has to go to the drier plant foods to really scale it up like beans at 15 grams or intact grains like barley over 30 grams per cup. But many people are avoiding common grains these days, like wheat, barley, and rye, due to gluten. But there is a dark side of gluten-free diets. Now if you have a condition like celiac disease, well then you absolutely have to avoid gluten. But if not, the downsides include the potential for nutritional deficiencies, like not getting enough fiber, and toxic compounds, for example the accumulation of heavy metals in people on gluten-free diets. Those following a gluten-free diet had significantly increased blood mercury levels, more arsenic flowing through their systems. The arsenic is likely due to increased rice consumption, because rice is a major ingredient in gluten-free foods. But you can certainly choose other grains, like sorghum, that's my favorite rice substitute. And the higher mercury may just be because people eating gluten-free diets were tending to eat more fish for some reason. But the reason that 10 out of 10 of those without celiac disease, or recognized gluten sensitivity following a gluten-free diet, is because the pro-inflammatory gastrointestinal environment is likely due to starving your microbial self, not getting enough prebiotics, not getting enough fiber because you're avoiding grains like wheat. So whatever diet you choose, for whatever reason, make sure you're getting enough fiber. In our next story, we look at how the effects of gluten on our health have been debated for more than 30 years. In 1980, researchers in England reported a series of women who suffered from chronic diarrhea that resolved on a gluten-free diet, yet did not have evidence of celiac disease, the autoimmune disorder associated with gluten intolerance. The medical profession was skeptical at the time, and even 30 years later. So much so that, much like patients who had irritable bowel syndrome, patients claiming non-celiac gluten sensitivity were commonly referred to psychiatrists, because they were believed to have an underlying mental illness. Psychological testing of such patients, however, found no evidence that they were suffering from some kind of psychosomatic hysteria. The medical profession has a history of dismissing diseases as all in people's heads. PTSD, ulcerative colitis, migraines, ulcers, asthma, Parkinson's, MS. Despite resistance from the prevailing medical community at the time, these health problems have subsequently been confirmed to be credible physiologically-based disorders rather than psychologically-based confabulations. On the flip side, the internet is rife with unsubstantiated claims about gluten-free diets, which has spilled over into the popular press to make gluten the diet villain du jour, with claims like 17 million Americans are gluten sensitive. However, it must be remembered that this is also big business. When literally billions of dollars are at stake, it's hard to trust anybody. So is always best to stick to the science. What sort of evidence do we have for the existence of a condition presumed to be so widespread? Not much. The evidence base for such claims was unfortunately very thin because we didn't have randomized controlled trials demonstrating that the entity even exists. The gold standard for confirming non-celiac gluten sensitivity requires a gluten-free diet followed by a double-blind, randomized, placebo-controlled food challenge, like you give someone a muffin, and they're not told if it's a gluten-free muffin or a gluten-filled muffin to control for placebo effects and see what happens. The reason this is necessary is because when you actually do this, a number of quote-unquote gluten-sensitive patients don't react at all to disguised gluten and instead react to the gluten-free placebo, so it truly was in their heads. But we never had that kind of level of evidence until 2011, when a double-blind, randomized, placebo-controlled trial was published which tested to see if patients complained of irritable bowel type symptoms who claimed they felt better on a gluten-free diet, despite not having celiac disease, actually could tell if they were given gluten-free bread and muffins or gluten-containing bread and muffins. They started out gluten-free and symptom-free for two weeks and then they were challenged with the bread and muffins. Here's what happened to the 15 patients who got the placebo, meaning they started out on a gluten-free diet and continued on a gluten-free diet, they got worse. Just a thought that they may be eating something that was bad for them made them feel all cramping and bloated. This is what's called a nocebo effect. The placebo effect is when you give someone something useless and they feel better. The nocebo effect is when you give someone something harmless and they feel worse. But the small group that got the actual gluten felt worse still. So they concluded this non-celiac gluten intolerance may actually exist. It was a small study, though, and even though they claimed the gluten-free bread and muffins were indistinguishable, maybe at some level the patients could tell which is which. So in 2012, researchers in Italy took 920 patients that had been diagnosed with non-celiac gluten sensitivity and put them to the test, with a double-blinded wheat challenge by giving them not bread and muffins, but capsules filled with wheat flour or filled with placebo flour, or kind of placebo powder. No flour at all. And more than two-thirds failed the test, like they got worse on the placebo or better on the wheat. But of those that passed, there was a clear benefit to staying on the wheat-free diet, confirming the existence of a non-celiac wheat sensitivity. Now note they said wheat sensitivity, not gluten sensitivity. Gluten itself may not be causing gut symptoms at all. See, most people with wheat sensitivity have a variety of other food sensitivities. Two-thirds are sensitive to cow's milk protein as well. Then eggs were the most common culprit after that. So if you put people on a diet low in common triggers of irritable bowel symptoms and then challenge them with gluten, there's no effect. Same increase in symptoms with high gluten, low gluten, or no gluten. Calling into question the very existence of non-celiac gluten sensitivity. Interestingly, despite being informed that avoiding gluten wasn't apparently doing a thing for their gut symptoms, many participants opted to continue following a gluten-free diet as they just subjectively described feeling better. So the researchers wondered if avoiding gluten might be improving the mood of those with wheat sensitivity and indeed. Short-term exposure to gluten appeared to induce feelings of depression in these patients. But whether non-celiac gluten sensitivity is a disease of the mind or the gut, it is no longer a condition that can be dismissed. Finally today, how common is gluten sensitivity? Are there benefits to gluten? Why does the medical profession explicitly advise against people who might suspect they may be gluten intolerant from just going on a gluten-free diet? Let's find out. Until only a few years ago, almost a whole the scientific world maintained that the wheat protein gluten would provoke negative effects only in people with rare conditions, such as celiac disease or wheat allergies. But by the early part of 2013, it was largely becoming accepted that some non-celiac patients could suffer from gluten or wheat sensitivity. And indeed, a consensus panel of experts now officially recognizes three gluten-related conditions, wheat allergy, celiac disease, and gluten sensitivity. So what percent of the population should avoid wheat? Well, about 1 in 1,000 may have a wheat allergy. Nearly 1 in 100 may have celiac disease. And it appears to be on the rise, though there's still less than about a 1 in 10,000 chance Americans will get diagnosed with celiac in any given year. How common is wheat or gluten sensitivity? Our best estimate at this point is that in that same kind of general range, slightly higher than 1%, but still that's potentially millions of people who may have been suffering for years who could have been cured by simple dietary means, yet went unrecognized and unhelped by the medical profession. Although gluten sensitivity continues to gain medical credibility, we still don't know how it works or how much gluten can be tolerated, if it's reversible or not, and what the long-term complications might be of not sticking to the diet. Considering the lack of knowledge, maybe people with gluten sensitivity should be trying to reintroduce gluten back into their diet every year or so to see if it's still causing problems. The reason health professionals don't want to see people on gluten-free diets and less absolutely necessary is that for the 98% of people that don't have gluten issues, whole grains, including the gluten grains wheat, barley, and rye, are health promoting a link to reduced risk of coronary heart disease, cancer, diabetes, obesity, and other chronic diseases. Just like because some people have a peanut allergy, doesn't mean that everyone should avoid peanuts. There's no evidence to suggest that following a gluten-free diet has any significant benefits in the general population. Indeed, there is some evidence to suggest that gluten-free diet may adversely affect gut health in those without celiac disease or gluten sensitivity or allergy. They're talking about this study. They found that a month on a gluten-free diet may hurt our gut flora and immune function, potentially setting those on gluten-free diets up for an overgrowth of harmful bacteria in their intestines. Why? Because ironically of the beneficial effects of the very components wheat-centered people have problems with, like the FODMAP fructans that act as prebiotics and feed our good bacteria, or the gluten itself, which may boost immune function less than a week of added gluten protein significantly increases natural killer cell activity, which could be expected to improve our body's ability to fight cancer and viral infections. High gluten bread improves triglyceride levels better than regular gluten bread, as another example. Ironically, one of the greatest threats of gluten-free diets may be the gluten itself. Self-prescription of a gluten-free diet may undermine our ability to pick up celiac disease, the much more serious form of gluten intolerance. The way we diagnose celiac is by looking for the inflammation caused by gluten in celiac sufferers. But if they haven't been eating a lot of gluten, we might miss the disease. Hence, rather than being on a gluten-free diet, we want celiac suspects to be on a gluten-loaded diet. We're talking four to six slices of gluten-packed bread a day, every day for at least a month, so we can definitively diagnose the disease. Why does it matter so much to get a formal diagnosis if you're already on a gluten-free diet? Well, it's a genetic disease, so you'll know to test the family. But most importantly, many people on gluten-free diets are not actually on gluten-free diets. Even 20 parts per million can be toxic to someone with celiac. Many on so-called gluten-free diets inadvertently still eat gluten. Sometimes there's contamination of gluten-free products, so even foods labeled gluten-free may still not be safe for celiac sufferers. That's why we need to know. The irony editorialized in a prominent medical journal of many celiac patients not knowing their diagnosis, while millions of non-suffers banish gluten from their diets, can be considered a public health force. We would love it if you could share with us your stories about reinventing your health through evidence-based nutrition. Go to nutritionfacts.org slash testimonials. We may be able to share it on social media to help inspire others. To see any graphs, charts, graphics, images, or studies mentioned here, please go to the Nutrition Facts podcast landing page. There you'll find all the detailed information you need, plus links to all the sources we cite for each of these topics. For a vital timely text on the pathogens that cause pandemics, you can order the e-book, audiobook, or the hard copy of my latest book, How to Survive a Pandemic, or go to your local public library, for that matter. For more recipes, check out my new How Not to Diet Cookbook. It's beautifully designed with more than 100 recipes for delicious and nutritious meals. And of course, all the proceeds I received from all the sales of my books go to charity. NutritionFacts.org is a non-profit science-based public service where you can sign up for free daily updates on the latest in nutrition research via bite-sized videos and articles, everything on the website is free. There are no ads, no corporate sponsorships, no kickbacks. It's strictly non-commercial, not selling anything. I just put it up as a public service, as the labor of love as a tribute to my grandmother, whose own life was saved with evidence-based nutrition.