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Should Autoimmune Patients Avoid Beans and Other Legumes?


In her New York Times bestselling book, The Paleo Approach, Sarah Ballantyne (aka The Paleo Mom) draws upon scientific research and her own battle with an autoimmune disease to provide autoimmune patients with a comprehensive Paleo-based diet and lifestyle plan. Like most other Paleo-based diet plans, this plan eschews beans and other legumes because of the anti-nutrients they contain. Let's take a look at how some of the most famous anti-nutrients found in beans and other legumes such as soy and peanuts might impact people with autoimmune diseases:

The Theory of How Saponins and Lectins in Beans Might Promote Autoimmunity

People in the Paleo community often talk about saponins. Now, for those who missed the memo, saponins are soap-like substances that occur naturally in a wide range of plants, including legumes, tomatoes and potatoes. The purpose of saponins is to protect plants against insect and microbe attacks by dissolving the cell membranes of these predators. But some of the most famous proponents of the Paleolithic diet, including Loren Cordain, the author of The Paleo Diet, maintain that bean saponins may be harmful not only to insects and microbes but also to people because of the potential of saponins to damage the gut lining due to their soap-like properties. This may be particularly problematic for autoimmune patients many of whom are believed to suffer from, or have an increased risk of, developing a condition called "leaky gut".

In healthy people, the gut wall acts as a barrier that prevents undigested food particles, microbes and other unwanted substances from leaking into the circulation, but in people with a leaky gut, the lining of the gut wall is damaged and these substances can enter the bloodstream where they have no business being. This in turn can overload the immune system and aggravate symptoms associated with autoimmune diseases. Test tube studies and animal studies suggest that some saponins may poke tiny holes in the gut lining, thereby promoting a leaky gut.

Like saponins, lectins are thought help prevent plants (and particularly their seeds) from being eaten by predators. While some lectins may be harmless to humans, others have properties that make them potentially problematic. Agglutinins, which are abundant in legumes like beans, are an example of a group of lectins that may be problematic for human health. The problem with these lectins is that they may act as gut irritants in genetically susceptible people, setting the stage for the same leaky gut and autoimmune responses as saponins. When it comes to agglutinins, autoimmune patients might want to be particularly wary of genetically modified beans because they have been engineered to produce more lectins to make them extra-resistant against attacks by insects and other pests.

The Other Side of the Story

Before you draw any definite conclusions about the ability of beans to promote autoimmunity, it is important to keep in mind that research on the gut-irritating activities of saponins and lectins is still in its infancy. And, almost everything we know about their activities is based on test tube studies and research conducted on animals, not on human studies.

It is also important to note that different legumes contain different amounts of anti-nutrients, which is relevant since the effects of saponins and lectins seem to be dose-dependent (check out this chart on the lectin content of beans. Plus, some types of legume lectins appear to be more toxic than others (peanut lectins appear to be particularly bad). What's more, pressure cooking and boiling destroy lectins, and according to studies, thoroughly cooked beans have little to no residual lectin activity—though some Paleo advocates would argue here that even the tiniest amounts of lectins may be problematic for autoimmune patients.

What's more, according to a study published in the June 2004 issue of the Journal of Agricultural and Food Chemistry, beans (particularly red beans and pinto beans) are extremely rich in antioxidants, beating foods like cultivated blueberries, cranberries and raspberries in terms of in vitro antioxidant capacity. Antioxidants have been extensively researched for their ability to prevent or fight all sorts of health problems, including autoimmune conditions such as psoriasis, and some (but not all) studies have shown promising results.

And there's even more. Some studies have actually found an inverse association between autoimmunity and legume-rich eating plans such as vegan and Mediterranean diets. For example, a cross-sectional observational case-control study published in the January 2015 issue of the Journal of Translational Medicine found a link between adherence to the traditional Mediterranean diet and a reduced risk of psoriasis. What is particularly interesting is that the PASI score and CRP levels, which were used to assess the severity of psoriasis in this study, were negatively correlated with the consumption of extra-virgin olive oil, fruit, vegetables, fish, nuts and—you guessed it—legumes!

Another study, published in the March 2003 issue of the peer-reviewed journal Annals of the Rheumatic Diseases, documented the benefits of the Mediterranean diet for rheumatoid arthritis patients. After following a Mediterranean-style diet for six weeks, most of the arthritic patients participating in this single-center, randomized, parallel study started to show significant improvement. They showed reduced inflammatory activity, increased physical function, and improved vitality. By comparison, no relief was reported by controls who followed a typical Western diet. Also a study published in the September 2007 issue of the Annals of the Rheumatic Diseases found that a switch to a Mediterranean-style diet, which was characterized by a high intake of fruit, vegetables, legumes and monounsaturated fat (in relation to saturated fat), eased the pain and morning stiffness associated with rheumatoid arthritis.

Now, in the light of the findings of the studies described above, it might be tempting to dismiss the whole theory of beans being bad for people with autoimmune diseases. Unfortunately, however, the studies described above cannot be used as a proof that beans are harmless or good for people with autoimmune diseases. Just because a person with an autoimmune disease experiences symptom relief on a diet that contains legumes such as beans does not mean that legumes are good for autoimmune patients. The studies referred to above looked at diets, not a single food group, and therefore we don't know to what extent various characteristics of the tested diets influenced the study outcomes. For example, it could be that the apparent anti-arthritis effects of the Mediterranean diet were solely due to the high intake of fish, vegetables, fruits and/or olive oil and that a Mediterranean-style diet that excludes legumes would have yielded even better results in some patients.

The Bottom Line

So, the bottom line is, we actually know very little about the effects of legumes such as beans in people autoimmune diseases. We have theories, and we have anecdotal evidence (supporting both sides), but hard scientific evidence based on multiple studies done in humans is simply not there at this point. The best thing you can do is keep checking out studies on the topic as they come in. And, of course, if you suffer from an autoimmune condition, you can experiment with a bean-free diet to see if it improves your condition—just make sure you get enough protein from other foods if you stop eating beans.

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Book You May Like
In her New York Times bestselling book, The Paleo Approach, Sarah Ballantyne draws upon cutting-edge research and her own battle with an autoimmune disease to provide you with a comprehensive Paleo-based diet and lifestyle plan for regulating the immune system and healing damaged tissues. Known as the Paleo Autoimmune Protocol, Ballantyne's groundbreaking plan emphasizes nutrient-dense foods and removes foods that promote inflammation and leaky gut syndrome. Also foods that stimulate the immune system are restricted on the AIP. In addition to explaining how eating certain foods and avoiding others can help put your condition into remission, this 400-plus page tome provides expert tips on how to "go Paleo" easily and economically. To learn more, or to order a copy, click here.