Overview

Food is obviously the foundation of nutrition and its quality and quantity will determine how healthy or how sick an individual will be. But what happens when one has an adverse reaction to the very thing they require to live? Basically, an adverse reaction to food appears to be either toxic (e.g. food poisoning) or non-toxic. A non-toxic adverse reaction takes one of three forms:

Food allergy, food intolerance, or food sensitivity.[1]

Food allergy is mediated by IgE antibodies (specific adaptive immunity) and may be so severe as to be life threatening (e.g. anaphylactic shock). This type of reaction is considered a “classic allergy” or “type 1 hypersensitivity reaction.”

Food intolerance refers to an inability to metabolize, digest, or absorb a food component (e.g. lactose intolerance due to lack of lactase enzyme). A pathophysiological food intolerance does not involve the immune system. Food intolerance symptoms tend to be confined to the GI tract (gas, bloating, abdominal distension).

Food sensitivity is currently defined as an adverse reaction to a food that is not due to an IgE- mediated reaction or a metabolic deficiency. It does, however, appear to involve an immune inflammatory reaction that may be local or systemic. Food sensitivities may also be referred to as delayed food hypersensitivities or even “hidden food allergies.” [2]

For simplification, consider that food intolerance refers to non-immune based reactions while food sensitivity refers to immune- based reactions that are non-IgE mediated. The terms food intolerance and food sensitivity have been used interchangeably in the past so don’t be surprised if you feel bewildered. Also keep in mind that some food sensitivity symptoms may mimic food allergy, so it is important to rule out IgE-mediated food allergies when assessing for sensitivities.[3]

This FYI focuses on food sensitivity testing and the most current research behind available testing methods. It does not address food intolerance or food allergy.

An adverse reaction to a food is often noticed because of the distressing nature of the symptoms, especially those that are gastrointestinal (GI) neurological, respiratory, or dermatological in nature. See “Signs and symptoms of food sensitivities.”

Signs and symptoms of food sensitivities

[4] [5] [6]

Cognitive/Neurological

  • Ataxia
  • Autism spectrum disorders (ASDs)
  • Behavioral problems
  • Disorganized or disturbed thinking and feeling
  • Headaches, migraines
  • Memory and concentration disturbances
  • Peripheral neuropathy
  • Psychological disturbances (anxiety, depression, panic attacks)

Gastrointestinal

  • Abdominal pain
  • Bloating
  • Constipation
  • Diarrhea, loose stools
  • Heartburn
  • Indigestion
  • Nausea
  • Vomiting

Musculoskeletal, joints, muscles, connective tissue

  • Arthritis
  • Inflammatory myopathies, myelopathies
  • Joint discomfort, pain, stiffness, swelling
  • Musculoskeletal discomfort

Respiratory

  • Food-induced bronchitis and asthma
  • Sneezing

 Skin

  • Dryness
  • Itching
  • Rashes
  • Redness
  • Scaling (as in eczema or psoriasis)
  • Swelling
  • Thickening

Systemic

  • Chills
  • Fatigue
  • Fever
  • Sweating
  • Weakness
  • Reduced exertional tolerance

“Clinically, complex health conditions without known cause are often found to improve by treating food sensitivities.” [7]

Immune System

Food sensitivity symptoms often involve the GI tract but can also be systemic. Related symptoms may be delayed and can occur hours or even days after exposure, making the primary “trigger” difficult to identify. In addition, “biochemical individuality” can influence how one reacts to a certain food or food component. This individuality may be influenced over time by many factors including the health of the gastrointestinal tract; the diversity of the GI microbiome; stress and psychological factors; physical activity; and even hormonal changes. [8]

An overburdened immune system can contribute to an “overreaction” of the immune system and can manifest as food sensitivities. This phenomenon is known as toxicant-induced loss of tolerance (TILT). In effect, TILT is due to an “overloaded” immune system, a phenomenon that can occur when a certain threshold of exposure to toxins, chemicals, radiation, etc. has been surpassed. The immune system then becomes dysfunctional and loses tolerance to seemingly harmless compounds including foods.[9]

Sensitization to foods may manifest as a “true” food allergy which is mediated by IgE antibodies from the adaptive/specific immune system. However, food components can also activate the innate/non-specific immune system without the involvement of antibodies. Activation of the innate system triggers a series of immune mechanisms, especially inflammation. Non-celiac gluten sensitivity is believed to be such an innate immune response.[10] [11]

The innate immune system may become chronically activated as it functions as a “first responder” to a perceived threat. Innate immune cells, primarily neutrophils, release a cascade of pro-inflammatory mediators and reactive oxygen species that can contribute to chronic inflammation, cell dysfunction, and tissue damage. [12] [13] Underlying “silent” inflammation can contribute to the multitude of symptoms associated with food sensitivity. The innate immune system can also recruit the adaptive system, compounding and magnifying food and chemical-related reactions.

 

Food sensitivity testing

The clinical imperative in food sensitivity testing is recognizing an immune inflammatory response and identifying which foods/compounds are actually causing that response.

 

Testing for food sensitivities has become increasingly popular for assisting individuals in the identification and elimination of food and chemical triggers. This brings us to the question of which test is best for reliably identifying food sensitivity triggers?

 

Types of food sensitivity testing

Currently, the most popular food sensitivity testing includes IgG immunoglobulin testing, leukocyte activation testing, and mediator release testing. Other testing may be available such as complement antigen testing, ELISA ACT lymphocyte response testing, and applied kinesiology. These tests are less common and less researched, and will not be covered here.

 

IgG antibody testing

Immunoglobulin testing for food sensitivities measures IgG antibodies using the Enzyme Linked Immunosorbent Assay (ELISA) method. While some testing measures total IgG (IgG1, IgG2, IgG3, and IgG4), the IgG4 is appears to be the antibody that is associated with food exposure. Although testing may detect the presence of food-specific IgG4, it does not assess for or measure a pathological process.

Early research presumed that IgG antibodies were pathological and would trigger an adverse reaction and cause symptoms upon food exposure. Some research appeared to correlate symptoms with the presence of serum IgG.[14] [15] [16] [17] However, the most contemporary research suggests that the presence of food-specific IgG antibodies may indicate not only exposure but tolerance to a particular food. [18] [19] In fact, IgG4 antibodies may be protective and actually help sustain tolerance to a food or compound.[20] [21] [22] Antibodies of the IgG class may even serve to “block” negative effects of IgE antibodies, further serving a protective role versus a pathogenic role.[23] [24]

 

About IgG

Expert committees of international scientific societies do not recommend the use of IgG antibody testing for the detection of food allergies or food sensitivities.[25]

The European Academy of Allergology and Clinical Immunology (EACCI):

  • Titrating IgG4 against foods is not recommended as a diagnostic tool as IgG4 indicates repeated exposure to a food and is considered a marker of immune tolerance associated with the activity of regulatory T cells.
  • “Specific IgG4 antibodies do not indicate food allergy or intolerance but a physiological response to the exposure to food.”

The International Consensus ON (ICON) document on food allergy (EAACI, American Academy of Allergy, Asthma & Immunology (AAAAI), and World Allergy Organization (WAO):

  • Emphasizes that the titration of specific IgG against foods is not a recommended test in the diagnosis of food allergy.

2014 Food Allergy Guidelines prepared by experts from American Academy of Allergy, Asthma & Immunology (AAAAI), American College of Allergy, Asthma & Immunology (ACAAI), Joint Council of Allergy, Asthma & Immunology (JCAAI)

  • State that titration of allergen-specific IgG and IgG4 is not recommended in the diagnosis of non-IgE-mediated food allergies.

 

The Alcat Test

Leukocyte activation testing

Leukocyte (white blood cell) activation testing identifies and measures immune cell responses to foods and other ingested compounds. White blood cells (e.g. neutrophils which are most abundant, macrophages/monocytes, eosinophils, basophils, and lymphocytes) release a variety of pro-inflammatory mediators that cause the local and systemic symptoms of food and chemical sensitivity. When white blood cells are stimulated/activated by an offending trigger, they undergo measurable changes which can then be measured by leukocyte activation testing.

During testing, white blood cells from a patient sample are exposed to a wide array of extracts (foods, herbs, spices, chemicals, additives, etc.) while changes at the cellular level are recorded and measured. The testing utilizes impedance cytometry to detect cellular changes such as

  • Increase in cell volume (production of mediators, loss of segmentation)
  • Decrease in cell volume (degranulation, initiation of apoptosis)
  • Decrease in cell number (apoptosis, necrosis, pyropoptosis, NETosis, cell burst, ejection of cell contents)

Remember, the immune cell response is designed to neutralize and eliminate threats such as pathogens, damaged proteins and DNA, cellular debris, etc. It is a potent reaction and can effectively rid the body of intruders and potentially damaging compounds. However, a chronically activated or imbalanced immune system can mount a damaging response to seemingly harmless foods or food components.

Leukocyte activation testing has a long history of clinical use, Early research, documented in professional medical presentations, correlated test outcomes with double-blind challenge results, providing early objective validation of this testing method.[26] [27] [28] [29] [30]

A widening base of research correlates leukocyte activation results with biomarkers indicative of an immune inflammatory response, perhaps providing the long sought-after “smoking gun” underlying food sensitivities.[31] [32] [33]

A comprehensive program will include elimination and controlled reintroduction of immune inflammatory triggers. If sensitivity to a food or compound persists (e.g. non-celiac gluten sensitivity), then lifelong elimination of that food or substance should be maintained.

Validated studies and research

Yale University research supports leukocyte activation testing as a screening tool to identify foods and compounds that cause the immune inflammatory reactions associated with food sensitivity.

 

Leukocyte activation testing provides foundation for individualized dietary plans effective in IBS.

Patients with irritable bowel syndrome demonstrated significant improvements when they eliminated foods that tested as severely reactive on leukocyte activation testing. Symptom reduction correlated with a decrease in plasma elastase. Elastase, an inflammatory compound widely distributed in innate immune cells, can damage tissue, disrupt tight junctions, and potentially contribute to increased intestinal permeability.

-Ali A, Weiss TR, McKee D, Scherban A, Khan S, Fields MR, Apollo D, Mehal WZ. Efficacy of individualised diets in patients with irritable bowel syndrome: a randomised controlled trial. BMJ Open Gastroenterol. 2017 Sep 20;4(1):e000164. doi: 10.1136/bmjgast-2017-000164. eCollection 2017. PubMed PMID: 29018540; PubMed Central PMCID: PMC5628288. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5628288/

 

Online presentation of study results (Live Q&A with Dr. Mehal): Link

Functional Forum podcast with researcher Dr. Mehal: Link

Yale News Individualized diets for irritable bowel syndrome better than placebo : Link

Reader’s Digest Guess What: Your Irritable Bowel Syndrome May Actually Be Caused By Food Sensitivities : Link

 

Mediator release testing

Mediatory release testing for food sensitivities measures volumetric changes around white blood cells that occur when cells are exposed to a variety of substances. Mediatory release testing

Is based on the premise that volumetric changes around immune cells reflect inflammatory activity. This method combines flow cytometry technology with an impedance-based “Ribbon Method.” Published clinical research is limited for this method.

Takeaway for practitioners

Practitioners should maintain awareness that chronic immune inflammatory activity may be responsible for a wide variety of symptoms including those that affect gastrointestinal, neurological, musculoskeletal, and integumentary systems. When this underlying chronic inflammation is related to ingested food or chemicals, triggers should be identified and eliminated.

  • A variety of testing for food sensitivities is available commercially. The most current and compelling research supports leukocyte activation testing for identification of specific food and chemical triggers.
  • Although popular, IgG food sensitivity is not considered a diagnostic tool and may simply reflect exposure and tolerance, not a potential pathogenic trigger.
  • Remember that food sensitivity testing does NOT test for IgE-mediated hypersensitivity reactions and will not detect an IgE-mediated food allergy.
  • When food sensitivity symptoms are identified and even once triggers are being eliminated, remember to counsel the patient on an anti-inflammatory diet[34] [35] high in
    • Omega-3 fatty acids
      • Especially wild-caught cold-water fish, flaxseeds, chia seeds, hemp seeds, organic canola oil
    • Vegetables and fruits
      • Especially dark leafy greens, cruciferous vegetables, onions, tomatoes, avocadoes, berries, cherries, purple grapes, pomegranates, and citrus fruits
    • Herbs and spices
      • Especially turmeric, chili powder, saffron, ginger, garlic, parsley, sage, dill, basil, rosemary, oregano, bay leaf, caraway, anise, fennel, black pepper, lemongrass, mint, clove, coriander, cinnamon, nutmeg
    • Other
      • Cocoa, green and black tea, nuts and seeds (especially almonds, cashews, Brazil nuts, walnuts, pumpkin seeds, sunflower seeds, and sesame seeds
    • Minimize or eliminate processed foods, commercial baked goods, commercial sweets, soda, trans fats, pesticide exposure/residues

Foundational Resources

Ali A, Weiss TR, McKee D, et al. Efficacy of individualised diets in patients with irritable bowel syndrome: a randomised controlled trial. BMJ Open Gastroenterol. 2017 Sep 20;4(1):e000164. doi: 10.1136/bmjgast-2017-000164. eCollection 2017. PubMed PMID: 29018540; PubMed Central PMCID: PMC5628288. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5628288/
Carr S, Chan E, Lavine E, Moote W. CSACI Position statement on the testing of food-specific IgG. Allergy Asthma Clin Immunol. 2012 Jul 26;8(1):12. Doi:
10.1186/1710-1492-8-12. PubMed PMID: 22835332; PubMed Central PMCID: PMC3443017. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3443017/
Genuis SJ. Sensitivity-related illness: the escalating pandemic of allergy, food intolerance and chemical sensitivity. Sci Total Environ. 2010 Nov 15;408(24):6047-61. doi: 10.1016/j.scitotenv.2010.08.047. Review. PubMed PMID: 20920818.

https://pdfs.semanticscholar.org/863d/edb58a324eb5bf93e4f48b7c4795c375b7dd.pdf

Gocki J, Bartuzi Z. Role of immunoglobulin G antibodies in diagnosis of food allergy. Postepy Dermatol Alergol. 2016 Aug;33(4):253-6. Doi: 10.5114/ada.2016.61600. Epub 2016 Aug 16. Review. PubMed PMID: 27605894; PubMed Central PMCID: PMC5004213. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5004213/

Lavine E. Blood testing for sensitivity, allergy or intolerance to food. CMAJ. 2012 Apr 3;184(6):666-8. doi: 10.1503/cmaj.110026. Epub 2012 Mar 19. PubMed PMID: 22431905; PubMed Central PMCID: PMC3314037. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3314037/

Mahan, L. K., & Raymond, J. L. (2016). Krause’s food & the nutrition care process. Elsevier Health Sciences.

Pietschmann N. Food Intolerance: Immune Activation Through Diet-associated Stimuli in Chronic Disease. Altern Ther Health Med. 2015 Jul-Aug;21(4):42-52. Review. PubMed PMID: 26030116.

Valenta R, Hochwallner H, Linhart B, et al. Food allergies: the basics. Gastroenterology. 2015 May;148(6):1120-31.e4. doi: 10.1053/j.gastro.2015.02.006. Epub 2015 Feb 11. Review. PubMed PMID: 25680669; PubMed Central PMCID: PMC4414527. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4414527/

Cited References

[1] Mahan, L. K., & Raymond, J. L. (2016). Krause’s food & the nutrition care process. Elsevier Health Sciences.

[2] Mullin GE, Swift KM, Lipski L, Turnbull LK, Rampertab SD. Testing for food reactions: the good, the bad, and the ugly. Nutr Clin Pract. 2010 Apr;25(2):192-8. doi: 10.1177/0884533610362696. Review. PubMed PMID: 20413700

[3] Boyce JA, Assa’ad A, Burks AW, et al.  NIAID-Sponsored Expert Panel. Guidelines for the Diagnosis and Management of Food Allergy in the United States: Summary of the NIAID-Sponsored Expert Panel Report. J Allergy Clin Immunol. 2010 Dec;126(6):1105-18. doi: 10.1016/j.jaci.2010.10.008. PubMed PMID: 21134568; PubMed Central PMCID: PMC4241958.

[4] Mahan, L. K., & Raymond, J. L. (2016). Krause’s food & the nutrition care process. Elsevier Health Sciences.

[5] Mullin GE, Swift KM, Lipski L, Turnbull LK, Rampertab SD. Testing for food reactions: the good, the bad, and the ugly. Nutr Clin Pract. 2010 Apr;25(2):192-8. doi: 10.1177/0884533610362696. Review. PubMed PMID: 20413700

[6] Genuis SJ. Sensitivity-related illness: the escalating pandemic of allergy, food intolerance and chemical sensitivity. Sci Total Environ. 2010 Nov 15;408(24):6047-61. doi: 10.1016/j.scitotenv.2010.08.047. Review. PubMed PMID: 20920818.

[7] Mahan, L. K., & Raymond, J. L. (2016). Krause’s food & the nutrition care process. Elsevier Health Sciences.

[8] Mahan, L. K., & Raymond, J. L. (2016). Krause’s food & the nutrition care process. Elsevier Health Sciences.

[9] Genuis SJ. Sensitivity-related illness: the escalating pandemic of allergy, food intolerance and chemical sensitivity. Sci Total Environ. 2010 Nov 15;408(24):6047-61. doi: 10.1016/j.scitotenv.2010.08.047. Review. PubMed PMID: 20920818.

[10] Valenta R, Hochwallner H, Linhart B, Pahr S. Food allergies: the basics. Gastroenterology. 2015 May;148(6):1120-31.e4. doi: 10.1053/j.gastro.2015.02.006. Epub 2015 Feb 11. Review. PubMed PMID: 25680669; PubMed Central PMCID: PMC4414527.

[11] Sapone A, Lammers KM, Casolaro V, et al. Divergence of gut permeability and mucosal immune gene expression in two gluten-associated conditions: celiac disease and gluten sensitivity. BMC Med. 2011 Mar 9;9:23. doi: 10.1186/1741-7015-9-23. PubMed PMID: 21392369; PubMed Central PMCID: PMC3065425.

[12] Mahan, L. K., & Raymond, J. L. (2016). Krause’s food & the nutrition care process. Elsevier Health Sciences.

[13] Pietschmann N. Food Intolerance: Immune Activation Through Diet-associated Stimuli in Chronic Disease. Altern Ther Health Med. 2015 Jul-Aug;21(4):42-52. Review. PubMed PMID: 26030116.

[14] Atkinson W, Sheldon TA, Shaath N, et al. Food elimination based on IgG antibodies in irritable bowel syndrome: a randomised controlled trial. Gut. 2004 Oct;53(10):1459-64. PubMed PMID: 15361495; PubMed Central PMCID: PMC1774223.

[15] Alpay K, Ertas M, Orhan EK, et al. Diet restriction in migraine, based on IgG against foods: a clinical double-blind, randomised, cross-over trial. Cephalalgia. 2010 Jul;30(7):829-37. doi:
10.1177/0333102410361404. Epub 2010 Mar 10. PubMed PMID: 20647174; PubMed Central
PMCID: PMC2899772.

[16] Aydinlar EI, Dikmen PY, Tiftikci A, Saruc M, Aksu M, Gunsoy HG, Tozun N. IgG-based elimination diet in migraine plus irritable bowel syndrome. Headache. 2013 Mar;53(3):514-25. doi: 10.1111/j.1526-4610.2012.02296.x. Epub 2012 Dec 6. PubMed PMID: 23216231.

[17] Bentz S, Hausmann M, Piberger H, et al. Clinical relevance of IgG antibodies against food antigens in Crohn’s disease: a double-blind cross-over diet intervention study. Digestion. 2010;81(4):252-64. doi: 10.1159/000264649. Epub 2010 Jan 30. PubMed PMID: 20130407.

[18] Mahan, L. K., & Raymond, J. L. (2016). Krause’s food & the nutrition care process. Elsevier Health Sciences.

[19] Gocki J, Bartuzi Z. Role of immunoglobulin G antibodies in diagnosis of food allergy. Postepy Dermatol Alergol. 2016 Aug;33(4):253-6. Doi: 10.5114/ada.2016.61600. Epub 2016 Aug 16. Review. PubMed PMID: 27605894; PubMed Central PMCID: PMC5004213. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5004213/

[20] Stapel SO, Asero R, Ballmer-Weber BK; EAACI Task Force. Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy. 2008 Jul;63(7):793-6. doi: 10.1111/j.1398-9995.2008.01705.x. Epub 2008 May 16. PubMed PMID: 18489614.

[21] Lavine E. Blood testing for sensitivity, allergy or intolerance to food. CMAJ. 2012 Apr 3;184(6):666-8. doi: 10.1503/cmaj.110026. Epub 2012 Mar 19. PubMed PMID: 22431905; PubMed Central PMCID: PMC3314037.

[22] Carr S, Chan E, Lavine E, et al. CSACI Position statement on the testing of food-specific IgG. Allergy Asthma Clin Immunol. 2012 Jul 26;8(1):12. Doi:
10.1186/1710-1492-8-12. PubMed PMID: 22835332; PubMed Central PMCID: PMC3443017.

[23] Uermösi C, Zabel F, Manolova V, et al. IgG-mediated down-regulation of IgE bound to mast cells: a potential novel mechanism of allergen-specific desensitization. Allergy. 2014 Mar;69(3):338-47. doi: 10.1111/all.12327. Epub 2013 Dec 19. Erratum in: Allergy. 2014 Aug;69(8):1118. PubMed PMID: 24354793.

[24] Collins AM, Jackson KJ. A Temporal Model of Human IgE and IgG Antibody Function. Front Immunol. 2013 Aug 9;4:235. doi: 10.3389/fimmu.2013.00235. eCollection 2013. PubMed PMID: 23950757; PubMed Central PMCID: PMC3738878.

[25] Gocki J, Bartuzi Z. Role of immunoglobulin G antibodies in diagnosis of food allergy. Postepy Dermatol Alergol. 2016 Aug;33(4):253-6. Doi: 10.5114/ada.2016.61600. Epub 2016 Aug 16. Review. PubMed PMID: 27605894; PubMed Central PMCID: PMC5004213.

[26] High Correlation of the Alcat Test Results with Double-blind Challenge (DBC) in Food Sensitivity Presentation at the 45th Annual Congress of the American College of Allergy and Immunology, Los Angeles, November 12-16, 1988; published in the Annals of Allergy.

[27] Alcat a new test for food induced problems in medicine? Presentation at the annual meeting of the American Academy of Otolaryngic Allergy, Washington DC, 1. October 1988.

[28] Alcat® – a new cellular test for food sensitivity. Presentation at the annual meeting of the American In-Vitro Allergy & Immunology Society, August 1990, Toronto, Canada.

[29] Cellular responses to food in irritable bowel syndrome – an investigation of the Alcat Test Publication of pooled study results in the Journal of Nutritional Medicine, Vol. 2, No. 2, 1991.

[30] Diagnostic Value of Alcat Test in intolerance to food additives compared with double-blind placebo-controlled (DBPC) oral challenges. Presented at the 52nd Annual Meeting of the American Academy of Allergy, Asthma & Immunology, New Orleans, LA. March 15-20, 1996. Publication in the Congress Proceedings of the Journal of Allergy and Clinical Immunology 1996;97:336.

[31] Ali A, Weiss TR, McKee D, et al. Efficacy of individualised diets in patients with irritable bowel syndrome: a randomised controlled trial. BMJ Open Gastroenterol. 2017 Sep 20;4(1):e000164. doi: 10.1136/bmjgast-2017-000164. eCollection 2017. PubMed PMID: 29018540; PubMed Central PMCID: PMC5628288.

[32] Ghani, A., Mehal, W., & Ali, A. Yale School of Medicine. (2014). Food reactivity on the ALCAT leukocyte activation test is associated with upregulation of CD11b on T cells. The Journal of Alternative and Complementary Medicine, 20(5), A35-A36.

[33] Garcia-Martinez, Weiss, Ali, et al. Alcat test identifies food items that result in release of inflammatory markers & activation of innate immune cells. The Journal of Alternative and Complementary Medicine. June 2016, 22(6): A1-A142.

[34] Mahan, L. K., & Raymond, J. L. (2016). Krause’s food & the nutrition care process. Elsevier Health Sciences.

[35] Dr. Weil’s Anti-Inflammatory Diet. https://www.drweil.com/diet-nutrition/anti-inflammatory-diet-pyramid/dr-weils-anti-inflammatory-diet/