What are Salicylates and Salicylate Intolerance?
Salicylates are natural plant chemicals that act as a defense mechanism, protecting plants from pests and diseases. For most people, these compounds are harmless. However, for those with a salicylate intolerance or sensitivity, consuming them can trigger adverse reactions. Symptoms can range from digestive issues like bloating and diarrhea to skin reactions such as hives and itchiness, or even respiratory problems like rhinitis and asthma. Salicylate intolerance is different from an allergy, though symptoms can overlap. Managing the condition often involves following a temporary low-salicylate elimination diet to identify and manage trigger foods.
The Conflicting Evidence on Onions
One of the most confusing aspects of a low-salicylate diet is the conflicting information surrounding certain common foods, and onions are a prime example. The variation in classification is linked to different research methodologies, onion varieties, and geographical dietary guidelines.
Very High Salicylate Classification
Some Australian dietary guidelines, such as the RPAH (Royal Prince Alfred Hospital) elimination diet, classify all onions (including white, brown, and Spanish varieties) as very high in salicylates. This classification is often used in the FAILSAFE diet, a strict elimination protocol for food chemicals. For this reason, individuals following these specific Australian protocols are advised to avoid onions altogether.
Low to Negligible Salicylate Classification
Conversely, numerous international studies and dietary lists classify onions as having low or negligible salicylate levels.
- A 2018 study in Taiwan, using gas chromatography-mass spectrometry, found cooked onions to have negligible free salicylic acid content.
- Another 2017 study from Europe classified white onions as having negligible salicylate levels.
- Broader low-salicylate diet resources, like those published by YorkTest and some chiropractic clinics, include onions on their lists of low-salicylate vegetables.
- An older 1985 study also listed fresh onions as low in salicylates.
Potential Reasons for Discrepancies
The stark difference in onion's salicylate classification can be attributed to several factors:
- Different Onion Varieties: The specific variety of onion tested (e.g., white, red, Spanish) may have differing levels of natural salicylates, leading to varied results.
- Growth and Environmental Factors: The salicylate content can be influenced by the plant's growing conditions, as salicylates are part of a plant's natural defense system.
- Cooking Methods: Some research indicates that cooking can alter salicylate content. A Taiwanese study noted negligible levels in cooked onions. However, the impact of cooking isn't universally agreed upon, and processing can sometimes increase salicylate availability.
- Varying Testing Methods: Different research groups may use different methods for extracting and measuring salicylates, leading to inconsistent findings.
Navigating a Low-Salicylate Diet with Confidence
Given the conflicting information, the best approach for anyone managing a salicylate sensitivity is a methodical, professionally-guided elimination and challenge process. The following steps and strategies are often recommended:
- Start with an Elimination Diet: Under the supervision of a healthcare provider or dietitian, remove all potential high-salicylate foods, including onions if you are unsure, for a set period. This helps reset your system and identify baseline symptoms.
- Gradual Reintroduction: After the initial elimination phase, reintroduce individual foods one at a time while monitoring symptoms. A food diary is an essential tool during this process.
- Consider Alternatives: Use confirmed low-salicylate ingredients to add flavor to your cooking. Leeks and the green tops of spring onions are common alternatives to onions.
- Optimize Gut Health: A compromised gut can play a role in salicylate intolerance by increasing intestinal permeability. Strategies to improve gut health, such as probiotics or dietary adjustments, may help with symptom management.
Comparison Table: Examples of Salicylate Content
| Food Category | Low/Negligible Salicylate Foods | High/Very High Salicylate Foods |
|---|---|---|
| Vegetables | Cabbage, celery, iceberg lettuce, peeled white potato, leeks | Broccoli, spinach, radishes, zucchini, tomatoes (especially processed) |
| Fruits | Pears (peeled), bananas, golden delicious apples, mango | Berries (blackberries, raspberries), grapes, oranges, pineapple |
| Grains | Rice, oats, millet, barley | Some corn products (check for additives) |
| Protein | Beef, poultry, pork, fish, eggs | Processed meats, prawns (sometimes listed moderately) |
| Oils/Fats | Sunflower oil, rice bran oil, butter, cashews | Olive oil, coconut oil, nut oils, almonds, peanuts |
| Herbs/Spices | Fresh parsley, chives, saffron, salt | Mint, paprika, cumin, curry powder, mustard, cinnamon |
Conclusion
While some reputable sources list onions as a very high salicylate food, others classify them as low or negligible, creating a clear contradiction in nutritional information. This divergence is likely due to differences in testing methods, onion varieties, and regional dietary guidance. For those with salicylate sensitivity, the definitive answer to are onions high in salicylates? is not straightforward and depends heavily on individual tolerance and the specific dietary protocol being followed.
Ultimately, managing salicylate intolerance requires a personalized approach. The most effective strategy involves working with a qualified healthcare professional, such as a dietitian, to undergo a controlled elimination and reintroduction diet. This allows you to accurately determine your own trigger levels and build a safe and sustainable nutritional diet without unnecessarily restricting beneficial foods.
For more detailed information on elimination diets and salicylate content, consulting established resources like the British Dietetic Association is a good next step. British Dietetic Association Salicylate Foods Link
