One of the most studied natural chemicals known to elicit an adverse reaction in humans, salicylates are ubiquitous components of food, triggering a host of unpleasant symptoms in susceptible individuals.

Not an easy condition to diagnose, salicylate sensitivity is both highly idiosyncratic and dose-dependent. Symptoms vary depending on the target organ susceptibility of the individual, and the amount ingested. Where an adverse reaction may lead to severe headache in one person, another may experience no headache at all, but instead skin rash or digestive issues. Symptoms can also fluctuate depending on the amount of salicylate consumed, with many sensitive people experiencing delayed symptoms due to ‘salicylate stacking’, a problem resulting from eating too many high salicylate foods in one sitting/day/week causing a person to overshoot their chemical threshold.

Based on observed symptoms of sensitive individuals along with improvement of symptoms on a modified diet, a number of health conditions have been associated with salicylate sensitivity. These include:

• Migraine
• Urticaria
• Angioedema
• Eczema
• Irritable bowel syndrome
• Chronic fatigue syndrome
• Asthma

Research shows that about 20% of adults with asthma (2), 60% of people with food-induced itchy rashes, headaches or migraines, 70% of people with irritable bowel symptoms (3), and 75% of children with behaviour problems (4) may be sensitive to salicylates, the chemical possibly aggravating these underlying disorders in susceptible people.

It’s not known exactly what causes food chemical sensitivity. However, clinical observations suggest a genetic predisposition along with hormonal factors as women are affected 2 to 3 times more frequently than men (1). The condition is also likely to have a pharmacological basis, with researchers hypothesising that symptoms result from an overproduction of leukotrienes, inflammatory mediators that are best known for their role in the development of asthma, rheumatoid arthritis and inflammatory bowel disease (5).

While reactions can begin at any age, many people are diagnosed in their 30s or 40s with symptoms either reported as gradual or occurring suddenly after a severe infection, adverse drug reaction and/or sudden change in diet (1).

Research is beginning to identify salicylate sensitivity as a multisystem disorder linked to a number of common health conditions. If you or someone you know has been diagnosed with one of the above-mentioned conditions or perhaps experiencing symptoms associated with chemical sensitivity, it may be worth talking to your health care provider to investigate whether salicylates are a factor in your symptoms/condition.

Brigid xx

References

(1) Loblay, Robert H. and Anne R Swain. “The Role of Food Intolerance in Chronic Fatigue Syndrome.” (2008)

(2) Jenkins C, Costello J, Hodge L. Systematic review of prevalence of aspirin induced asthma and its implications for clinical practice. BMJ. 2004 Feb 21;328(7437):434. doi: 10.1136/bmj.328.7437.434. PMID: 14976098; PMCID: PMC344260.

(3) Loblay RH, Swain AR. ‘Food intolerance’. In Wahlqvist ML, Truswell AS, Recent Advances in Clinical Nutrition. London: John Libbey, 1986, pages 169-177.

(4) Swain A, Soutter V, Loblay R, Truswell AS. Salicylates, oligoantigenic diets, and behaviour. Lancet 1985;2(8445):41-2.

(5) Szczeklik A, Sanak M, Nizankowska-Mogilnicka E, Kiełbasa B. Aspirin intolerance and the cyclooxygenase-leukotriene pathways. Curr Opin Pulm Med. 2004 Jan;10(1):51-6. doi: 10.1097/00063198-200401000-00009. PMID: 14749606.