Understanding Salicylate Sensitivity

The family of compounds called salicylates is found naturally in many plants, but the amount can vary depending on the plant species and its growing conditions. Aspirin, or acetylsalicylic acid (ASA), is probably the best-known member of the salicylate family. It is a derivative of salicylic acid which originated from plant extracts, such as willow bark, due to its analgesic properties.

The differences in how medications with ASA are absorbed compared to foods with salicylate are thought to play a role in how the body responds to these chemicals. Aspirin intolerance has been reported more often among individuals with asthma and may present symptoms that are similar to those associated with sensitivities to sulfites, benzoates, food dyes or other nonsteroidal anti-inflammatory drugs (NSAIDs).

While some attempts have been made to measure the salicylate content of foods, variations exist in the foods themselves, as well as the methods of analysis. The highest concentrations of salicylic acid [measured in milligrams (mg) per gram] have been found in some herbs and spices, such as cumin, curry powder, dill powder, garam masala, oregano, paprika, rosemary, thyme and turmeric. It is also found in tea and coffee, as well as condiments and sweeteners, such as Worcestershire sauce and honey.

Most fruits are considered to have a high salicylate content, especially in their dried form. Some examples are raisins, prunes, raspberries, apricots, blueberries, currants, dates, oranges and pineapples. Whereas vegetables vary greatly in their salicylate content, with broccoli, chili peppers, cucumber, okra, spinach, squash, sweet potato, canned tomatoes, tomato paste and sauce, green peppers, radishes, and zucchini measuring higher amounts.

Salicylate intake from dietary sources has been estimated to be 10 to 200 mg per day with higher amounts suspected by vegetarians. In comparison, a regular strength aspirin for adults provides 300 to 325 mg of ASA, with the potential for 600 to 650 mg to be ingested at one time and multiple times per day.

While there have been no laboratory tests available for diagnosing a salicylate intolerance, individuals may be diagnosed with a sensitivity to aspirin or NSAIDs. These patients are not typically placed on a low-salicylate diet, but there has been some research to evaluate its effectiveness in reducing symptoms.

A recent non-randomized study investigated the effect of a personalized low-salicylate diet on the reduction of symptoms related to asthma, rhinosinusitis and urticaria. Thirty patients who were diagnosed with a hypersensitivity to NSAIDs, yet continued to experience symptoms associated with salicylate hypersensitivity despite pharmaceutical treatment and avoidance of NSAIDs were enrolled.

Dietary instruction and support were provided by a dietitian with expertise in food intolerance and allergy management. Study participants followed a personalized low-salicylate diet for two to four weeks, which permitted foods with "less than 0.05 mg of total salicylates/serving," no more than one serving per meal and a maximum of five servings per day.

Self-reported symptoms related to hypersensitivity significantly improved for 22 of the patients compared to four who experienced a moderate improvement and four who reported worsening of symptoms or no change. A majority of participants also experienced favorable results following the personalized low-salicylate diet in terms of controlling their asthma, remission from urticaria, and fewer symptoms of rhinosinusitis.

Another study published in 2021, which is very small in comparison with only seven participants, examined the effect of a short-term intervention of following a low- versus high-salicylate diet and their effect on inflammatory markers in patients with "aspirin exacerbated respiratory disease" (AERD). This prospective, randomized, cross-over study found no correlation with the urinary biomarkers that were measured, but the severity of self-reported nasal symptoms improved after only one week.

After noting the limitations, the study authors suggested a low-salicylate diet may serve as an adjunctive therapy for patients with AERD, but more research is needed. They also recommended that this type of diet be "introduced and monitored by an experienced dietitian."

Because registered dietitian nutritionists may encounter patients seeking guidance on a low salicylate diet without a formal diagnosis, it's important to be aware of sensitivities that could influence similar symptoms, as well as the limitations of a salicylate restricted diet. As with other food intolerances, a salicylate intolerance is considered to be dose-dependent, so some individuals with a hypersensitivity may find avoiding foods with higher amounts of salicylate may only be needed.

Adherence to a low-salicylate diet can also be a concern, as both studies indicated. Individuals who are motivated to follow a low-salicylate diet are advised not to extend it beyond four weeks due to its restrictive nature and risk of nutritional deficiencies.

References:

• Kęszycka PK, Lange E, Gajewska D. Effectiveness of Personalized Low Salicylate Diet in the Management of Salicylates Hypersensitive Patients: Interventional Study. Nutrients. 2021 Mar 19;13(3):991.
• Sowerby LJ, Patel KB, Schmerk C, Rotenberg BW, Rocha T, Sommer DD. Effect of low salicylate diet on clinical and inflammatory markers in patients with aspirin exacerbated respiratory disease - a randomized crossover trial. J Otolaryngol Head Neck Surg. 2021;50(1):27. Published 2021 Apr 23. doi:10.1186/s40463-021-00502-4.
• Joneja JV. Chapter 26: Salicylate Intolerance. In: The Health Professional's Guide to Food Allergies and Intolerances. Chicago, IL: Academy of Nutrition and Dietetics; 2013.
• Swain AR, Dutton SP, Truswell AS. Salicylates in foods. J Am Diet Assoc. 1985;85:950-960.