Salicylic acid in soups prepared from organically and non-organically grown vegetables

Summary

Background Salicylic acid is a chemical signal in plants infected by pathogens and it is responsible for the anti-inflammatory action of aspirin. Patients who take aspirin have a reduced risk of developing atherosclerosis and colorectal cancer, both of these pathologies having an inflammatory component. Dietary salicylic acid may help to prevent these conditions. We wondered if foods made from organically-reared plants might have a higher content of salicylic acid than those made from non-organic plants, since the latter are more likely to be protected from infection by the application of pesticides. Objective To determine if organic vegetable soups have a higher salicylic acid content than non-organic vegetable soups. Methods The contents of salicylic acid in organic and non-organic vegetable soups purchased from supermarkets were determined. Salicylic acid was identified by varying the chromatographic conditions and comparing the retention times of the unknown substance in the extracts with salicylic acid; by treating extracts of the soups with salicylate hydroxylase; and by using GCMS. Salicylic acid was determined by using HPLC with electrochemical detection. Results Salicylic acid was present in all of the organic and most of the non-organic vegetable soups. The median contents of salicylic acid in the organic and non-organic vegetable soups were 117 (range, 8–1040) ng · g⁻¹ and 20 (range, 0–248) ng · g⁻¹ respectively. The organic soups had a significantly higher content of salicylic acid (p=0.0032 Mann Whitney U test), with a median difference of 59 ng · g⁻¹ (95 % confidence interval, 18–117ng · g⁻¹). Conclusions Organic vegetable soups contained more salicylic acid than non-organic ones, suggesting that the vegetables and plants used to prepare them contained greater amounts of the phenolic acid than the corresponding non-organic ingredients. Consumption of organic foods may result in a greater intake of salicylic acid.