An elimination diet is the gold standard for identifying food sensitivities. The basic premise is to remove an item from your diet for 3-4 weeks, reintroduce it and observe the effects. If the reintroduction increases symptoms, the food should be kept out of your diet at least for the short-term. It is important to reintroduce items one at a time (e.g., butter as butter not as a component in a wheat-flour-based cake) and in a quantity significant enough to cause a reaction (a few servings). Here is an example symptom tracker from the Institute for Functional Medicine (IFM).

Lab Tests and Food Sensitivities

There are lab tests to determine food sensitivities (e.g., IgG antibody testing), but there are limitations of them based on the test itself, as well as how the food is prepared, processed, and/or how frequently it is consumed by the individual (1,2). In addition, there are potentially problematic food additives and colorings for which specific testing is not available (3). Therefore, an elimination diet completely removes many of these factors and becomes a thorough means to determine the foods best tolerated. There are a lot of variants of the elimination diet and here is the punchline: they all have utility. No one elimination diet is perfect for everyone.  
Dairy and gluten (or wheat) are the most commonly eliminated items. Eliminating the “big-8” allergens would include dairy and wheat as well as eggs, fish, shellfish, tree nuts, peanuts, and soy (4). Paleo diets also exclude all grains, corn, potatoes, legumes, and peas. Other diets specify certain additives and types of added sugar to exclude, and some autoimmune protocols have limitations of specific vegetables such as nightshades and spices like cumin. Some people eliminate histamine or salicylate-containing foods like vinegar and green olives, respectively. There are FODMAP (Fermentable, Oligo-, Di-, Mono-saccharide And Polyol) diets where garlic, onions, and apples are off the table and some research indicates spinach may be problematic for people with multiple sclerosis (5). I just finished the IFM elimination diet that includes the exclusion of coffee, beef, and pork. Oh, my.  

Warnings From the Blogosphere

There is a certain amount of fearmongering that can occur in the blogosphere with warnings on any food such that if you are like me at all, at some point you find yourself down to the lamb-and-pear diet (Google it). It is possible that any food may be problematic for some, but that does not mean that all of them need to be avoided by everyone forever.   

There is a certain amount of fearmongering that can occur in the blogosphere with warnings on any food such that if you are like me at all, at some point you find yourself down to the lamb-and-pear diet (Google it).

While elimination diets are powerful tools, they are tools and not necessarily a representation of an optimal long-term diet. Particularly eliminating plant materials – such as legumes, vegetables, fruits, and even grains – limits the diversity of the micronutrients, fibers, and phytochemicals in your diet. (To be clear: this is legumes, vegetables, fruits and grains as the whole-food and kitchen prepped variety, not as components in processed foods.)   

The Importance of Micronutrient Diversity

Micronutrients (vitamins and minerals) are vital to one’s health, but no one food (even kale!), provides the optimal concentrations of all of them. Diverse plant matter also provides different fibers for the gut microbiota and being too restrictive can negatively impact it (and by extension, your health) (6,7,8). Plant material also contains more than 5,000 phytochemicals (think lycopene in tomatoes), many of which we do not yet know their health benefits (9). Why eliminate plant matter if you do not have to? Yes, eliminate the items not associated with health (e.g., high-fructose corn syrup) and any that are associated with symptoms for you, but keep and/or re-introduce the rest.
As an example, beans are often avoided. They do have lectins, but they also have fiber and polyphenols, were eaten by our ancestors, and are also associated with some pretty good glycemic control (10,11,12,13,14,15). [This is a good segway to discuss gas as a symptom. Gas is a natural byproduct of your gut microbiota eating fiber while also producing compounds like butyrate, which has systemic anti-inflammatory effects (16). Gas is not a foolproof symptom of an adverse reaction. Many people can eat beans without problem and also receive nutrient benefit (despite increased gas when compared to spinach).]
All the elimination diet variants are useful and can be used to determine individual responses to food. Certain foods for certain individuals should be avoided for life. People with celiac and gluten is a good example.  Other foods will have to be avoided for a period of time only; people may have fructose malabsorption due to a separate gastrointestinal issue. Once an underlying dysfunction is addressed, the individual can often re-assimilate some of the once problematic foods increasing nutrient diversity (and enjoyment!) in their diet.

References

1. Hodsdon, W. (2010). NMJ Original Research: Reproducibility and Reliability of Two Food Allergy Testing Methods. Natural Medicine Journal, 2(3). Accessed Aug 18, 2017, link HERE. 
2. Vojdani, A. (2009). Detection of IgE, IgG, IgA and IgM antibodies against raw and processed food antigens. Nutrition & Metabolism, 6(22), 1-17.
3. Lerner, A., & Matthias, T. (2015). Changes in intestinal tight junction permeability associated with industrial food additives explain the rising incidence of autoimmune disease. Autoimmunity Reviews, 14, 479-489.
4. Food & Drug Administration (FDA), 2017. Food Allergies: What You Need to Know.  Accessed Aug 18, 2017, link HERE. 
5. Vojdani, A., Mukherjee, P.S., Berookhim, J., & Kharrazian, D. (2015). Detection of Antibodies against Human and Plant Aquaporins in Patients with Multiple Sclerosis.  Autoimmune Diseases, 2015, 1-10. http://dx.doi.org/10.1155/2015/905208
6. Halmos, E.P., Christophersen, C.T., Bird, A.R., Shepherd, S.J., Gibson, P.R., & Muir, J.G. (2015). Diets that differ in their FODMAP content alter the colonic luminal microenvironment. Gut, 64, 93-100. doi:10.1136/gutjnl-2014-307264
7. Newell, C., Bornhof, M.R., Reimer, R.A., Hittel, D.S., Rho, J.M., Shearer, J. (2016). Ketogenic diet modifies the gut microbiota in a murine model of autism spectrum disorder. Molecular Autism, 7(37), 1-6. doi: 10.1186/s13229-016-0099-3
8. Sanz, Y. (2010). Effects of a gluten-free diet on gut microbiota and immune function in healthy adult humans. Gut Microbes, 1(3), 135-137.
9. Liu, R.H. (2013). Health-Promoting Components of Fruits and Vegetables in the Diet.  Advances in Nutrition, 4, 384S-392S. doi:10.3945/an.112.003517
10. Akond, G.M., Khandaker, L., Berthold, J., Gates, L., Peteres, K., Delong, H., & Hossain, K. (2011). Anthocyanin, Total Polyphenols and Antioxidant Activity of Common Bean. American Journal of Food Technology, 6(5), 385-394.
11. Bourassa, M.W., Alim, I., Bultman, S.J., & Ratan, R.R. (2016). Butyrate, neuroepigenetics and the gut microbiome: Can a high fiber diet improve brain health? Neuroscience Letters, 625(20), 56-63.
12. Fabbri, A.D., Schacht, R.W., Crosby, G.A. (2016). Evaluation of resistant starch content of cooked black beans, pinto beans, and chickpeas. NFS Journal, 3, 8-12.
13. Henry, A.G., Brooks, A.S., & Piperno, D.R. (2011). Microfossils in calculus demonstrate consumption of plants and cooked foods in Neanderthal diets (Shanidar III, Iraq; Spy I and II, Belgium). PNAS, 108(2), 486-491.
14. Thompson, S.V., Winham, D.M., & Hutchins, A.M. (2012). Bean and rice meals reduce postprandial glycemic response in adults with type 2 diabetes: a cross-over study.  Nutrition Journal, 11(23). https://doi.org/10.1186/1475-2891-11-23
15. Vojdani, A. (2015). Lectins, Agglutinins, and Their Roles in Autoimmune Reactivities.  Alternative Therapies in Health & Medicine, 21(1), 46-51.
16. Riviere, A., Selak, M., Lantin, D., Leroy, F., & De Vuyst, L. (2016). Bifidobacteria and Butyrate-Producing Colon Bacteria: Importance and Strategies for Their Stimulation in the Human Gut.  Frontiers in Microbiology, 7(979). doi: 10.3389/fmicb.2016.00979

[author] [author_image timthumb=’on’]https://i1.wp.com/crossfitroots.com/wp-content/uploads/2017/08/EC_Consult.jpg?zoom=2&w=1080/[/author_image] [author_info]EC is a candidate for an MS in Human Nutrition and Functional Medicine anticipated in December 2017. She also has a BS in Biochemical Engineering and an MS in Environmental Sciences. EC is a Certified CrossFit Level 4 (CF-L4) Coach and worked as a Flowmaster on the CrossFit, Inc. seminar team for more than 10 years. Her strong science background, combined with the practical experience of coaching others, brings a unique ability to provide recommendations tailored to an individual’s goals and needs. You can learn more about her practice here.[/author_info] [/author]