Nuts and seeds in moderation are a health-promoting food (see Nuts and the Paleo Diet: Moderation is Key); however, people with autoimmune disease so commonly develop food intolerance to nuts and seeds that they are eliminated on the Autoimmune Protocol.
Nuts and Seeds Are Common Food Intolerances
Tree nuts are one of the most allergenic foods, with true allergies (meaning the body produces IgE antibodies against proteins in nuts) estimated at about 1% of the total population and some preliminary scientific studies showing that nut intolerance (meaning the body produces IgG antibodies against proteins in nuts) may affect a whopping 20 to 50% of us. And, people with autoimmune disease are more likely to test positive on food intolerance panels than healthy people.
One study evaluated the level of IgG antibody production in autoimmune disease sufferers compared to healthy controls and found that autoimmune disease sufferers produce double and up to 10X more IgG antibodies against foods than healthy people.
The most common food intolerances in people with autoimmune disease are the foods already eliminated on the AIP because they are inflammatory, disrupt hormones, or negatively impact gut barrier health, including grains, dairy, egg whites and legumes (see How Gluten (and other Prolamins) Damage the Gut, Worse than Gluten: The Agglutinin Class of Lectins, 3 Myths About Legumes — Busted!, The WHYs behind the Autoimmune Protocol: Eggs). The other foods that test positive with high frequency are nuts and seeds.
One study compared the frequency of IgG food intolerance in Inflammatory Bowel Disease sufferers compared to healthy controls. Nut and seed intolerance was very common, especially in Crohn’s disease sufferers.
|Nuts & Seeds||% Crohn’s patients with IgG Ab||% healthy controls with IgG Ab|
In another study of people with unexplained gastrointestinal symptoms, something that is incredibly common among autoimmune disease sufferers, cashews are one of the most common nut intolerances, affecting upwards of 50% of study participants. In comparison, incidence of intolerance to almonds was about 28%, Brazil nuts was 23% and walnuts was 3%.
|Food||% IBS Patients with IgG Ab|
In yet another study of people with unexplained allergy symptoms, also common among autoimmune disease sufferers, pistachios were one of the most common nut intolerances, affecting upwards of 60% of study participants.
Taken together, these studies make a strong case for eliminating nuts and seeds when first adopting the Autoimmune Protocol.
Testing for Allergy and Intolerance
For those nut and seed lovers out there who just can’t wrap their heads around elimination of these otherwise nutrient-dense and health-promoting foods, you may consider testing for food allergy and intolerance to nuts and seeds and decide which to eliminate based on the results. This can be done with a blood test that looks for IgE and IgG antibodies (and rarely, but sometimes IgA and IgM antibodies) against various food antigens. Panels can include anywhere between 50 and 500 different foods. You typically have to have eaten the food within the previous month in order for it to show up as a positive if you are intolerant (so you can’t necessarily believe a negative result if you haven’t eaten that food in a while). These tests can be an excellent way to expedite the process of determining which nuts and seeds need to be eliminated. There are even at-home versions like EverlyWell.
Keep in mind that an elimination and challenge is considered the gold standard for identifying food intolerances. There are ways that we can negatively react to foods that we currently don’t have the capacity to test for. Furthermore, IgG and IgE food allergy/intolerance panels do have a fairly high false positive (10%) and false negative (30%) rate. This is actually about the same as skin prick tests for allergies, which is why allergists will often follow up testing with an elimination diet and food antigen challenge. You can read more about the challenge protocol in The Reintroduction Quick-Start Guide: A New FREE download!).
Other Reasons to Avoid Nuts and Seeds
Nuts and seeds are also relatively concentrated sources of phytates. Phytate is the salt of phytic acid—that is, it is phytic acid bound to a mineral. Within the seed, the primary function of phytic acid is as a storage molecule for phosphorus, but it also serves as an energy store, as a source of cations (positive ions) for various chemical reactions in the plant, and as a source of a cell wall precursor called myoinositol. Because phytate is formed when phytic acid binds to minerals—typically calcium, magnesium, iron, potassium, and zinc—these minerals are then unavailable to be absorbed by the gut. Therefore, the consumption of phytate-rich foods like grains and legumes can cause mineral deficiencies, especially when these phytate-rich foods displace other mineral-rich foods in the diet. Our gut bacteria can liberate some of these valuable minerals from phytates for us, but their capacity is limited, which might partially explain why we cease to see benefits from nut consumption beyond 20 grams daily.
Along with blocking mineral absorption, phytates also limit the activity of a variety of digestive enzymes, including the proteases trypsin and pepsin, as well as amylase and glucosidase. This means that phytates can be as devastating to the gut barrier and gut microbiota as digestive enzyme inhibitors, namely by increasing gut permeability (by stimulating the pancreas to release excess digestive enzymes) and feeding bacterial overgrowth (by inhibiting digestion).
It’s important to emphasize that excessive dietary phytate and phytic acid are the problem. Phytates are also present in much lower concentrations in nonreproductive plant parts (like leaves and stems). Consuming phytates in more moderate quantities may actually provide an important antioxidant function and help reduce cardiovascular risk factors and cancer risk. Also, moderate consumption means that a healthy amount and variety of gut bacteria will be able to liberate some minerals from the phytate and make them more absorbable. In that sense, the scientific literature reinforces the idea that vegetables (with their lower concentration of phytates) are extremely important in our diet, whereas grains deliver levels of phytates that surpass what benefits us, and of course, nuts and seeds are great in moderation.
Nuts and seeds typically contain a large amount of polyunsaturated fats, usually the proinflammatory omega-6 fatty acids (see Why Grains Are Bad, Part 2, Omega 3 vs. 6 Fats and The Importance of Fish in Our Diets). Even the highest omega-3 content nuts (like walnuts) still have ratios of omega-6 to omega-3 fatty acids in the neighborhood of 3 to 1, and many nuts and seeds only contain trace omega-3 fatty acids. Although their omega-6 content has often been used as rationale for limiting nut and seed consumption, most evidence suggests that when these foods are consumed in moderate amounts in whole form (opposed to highly processed oils stripped of most micronutrients and phytochemicals), their net effect is antiinflammatory due to the presence of other beneficial compounds—such as vitamin E, dietary fiber, L-arginine, and phenolic compounds. In other words, omega-6 content alone doesn’t appear to be a reason to cut out nuts and seeds completely and instead reinforces the concept of moderate consumption.
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