Image by Pexels from Pixabay

Salicylates are a compound produced by plants as a defense mechanism against insects and fungi. They’re thus found in a number of fruits and vegetables, and also in herbs used for medicinal purposes. Aspirin is probably best known for its salicylate content, originally derived from the medicinal herb called willow bark.

Salicylates are in the phenol family. The body has several pathways to potentially detoxify and eliminate them—but for some people, these pathways are compromised. This is when salicylate sensitivity occurs.

Causes of Salicylate Sensitivity Symptoms

Aspirin, and all NSAID drugs, work for pain by blocking cyclooxygenase enzymes, abbreviated as COX. This enzyme produces a compound called prostaglandins, most of which are inflammatory—so aspirin and NSAIDs are considered anti-inflammatory, as they block inflammatory prostaglandin production.

Those who are sensitive to salicylates can’t eliminate them well, which means the salicylates continue to block COX, leading to a “reroute” in the metabolic pathway; suppression of prostaglandins means an increase in production of alternative compounds called leukotrienes. High levels of leukotrienes can cause asthma; up to 22% of adults with asthma are sensitive to salicylates.

Other common symptoms include allergic rhinitis and chronic nasal polyps, as well as allergic responses, such as hives, red and itchy skin, and even anaphylaxis.

The symptoms are due to the fact that the salicylates cause this biochemical reroute to excessive leukotrienes–but the reason salicylates would be high in the first place (aside from overdose of medications like aspirin) primarily has to do with blocked elimination pathways.

Salicylate Metabolism

The liver has six main pathways for phase 2 detoxification in general. Many compounds can pass through more than one of these pathways. Salicylates can be eliminated through three of them.

The primary elimination pathway is via an enzyme called phenol sulfurtransferase, so named because it involves transfer of a sulfate molecule. This is why people who are sulfur sensitive are often also sensitive to salicylates—if they aren’t able to turn the sulfur in food into sulfates, there won’t be enough sulfates for salicylate elimination, either. Sulfur is also critically necessary for healing the gut, so this may be the underlying reason why many people with chronic food sensitivities and irritable bowel disease often have salicylate sensitivity too.

A secondary pathway for salicylate elimination is the glucuronidation pathway. Glucuronic acid is derived from glucose.

Finally, the amino acid conjugation pathway adds the side group glycine to salicylates for elimination, though the amount by which the body uses this as a pathway of elimination varies. Amino acid conjugated compounds require the body to be alkaline for elimination to occur, which may be the reason why renal excretion of salicylates is far more efficient with alkaline urine.

Sources of Salicylates

Natural salicylates are found in otherwise healthy foods, though of course the concentration in each food varies (and lists of high salicylate foods found online will vary in their definitions of what constitutes a “high” amount.) In general, though, high salicylate foods include red grapes (due to resveratrol, as well as quercetin), apples (also high in quercetin), berries, eggplants, citrus, cucumbers, peanuts, peppers, avocados, zucchini, broccoli, spinach, cantaloupe, watermelon, dates, watercress, artichoke, and most herbs and spices.

Obviously avoiding all of these healthy foods indefinitely isn’t the best solution, though it may be necessary in the short-term.

Other artificial sources include artificial colors, flavors, and preservatives—and of course it’s a good idea to avoid these anyway, as anything containing these sources of salicylates is also necessarily highly processed.

Testing for Salicylate Sensitivity

Urinary Organic Acid (OAT) testing is the best way I know of to identify a salicylate sensitivity, though if someone is completely avoiding salicylates, we’d expect the levels to be low, regardless.

Commercial labs do have salicylate serum testing, though my understanding is that these are most useful for very high sources such as aspirin, and are probably less useful for detecting smaller amounts.

Treatment for Salicylate Sensitivity

Since the primary pathway for salicylate elimination requires adequate levels of sulfates, my suspicion is that the primary cause of salicylate sensitivity is a sulfur deficiency. I wrote here about potential causes for this. In addition to eating a higher sulfur-containing diet, supplements containing sulfur include methionine, cysteine, and taurine, and production of sulfates from these amino acids requires molybdenum as a cofactor, as well as support for the methylation pathway.

For those with sulfur sensitivity (usually also those who are sulfur deficient), there are some back door ways to support sulfate levels, including Epsom salt baths and molybdenum especially.

Those with Gilbert’s Syndrome, or chronically elevated bilirubin, struggle with glucuronidation. This could be a cause of salicylate sensitivity too, especially in combination with low sulfates. The best support for this pathway is Calcium D-glucarate, as well as vitamins and magnesium.

If glycine is low (and it very often is, for a number of reasons), adding this in can be helpful for salicylate elimination, as long as the body is sufficiently alkaline. There are a number of possible reasons why it might not be, but one quick way to raise the pH in a hurry is with baking soda and deep, slow breathing.

Omega-3 Essential Fatty Acids have also been shown to help control salicylate sensitivity. I suspect this is because it helps to shift the body away from the inflammatory omega-6 prostaglandin and leukotriene pathways altogether. This shouldn’t therefore have any impact on salicylate elimination, but should only decrease sensitivity to them.

The Upshot

If you’re sensitive to high salicylate foods, in the short term, avoiding them may be beneficial. But the better long-term solution is, as always, to identify and correct the problem.