Urinary salicylate excretion in subjects eating a variety of diets shows that amounts of bioavailable salicylates in foods are low.
Intake of acetylsalicylic acid reduces the risk of cardiovascular disease and is associated with a decreased risk for colorectal cancer. Amounts of salicylates in foods are thus of interest, but data are scarce and controversial. We gave 58 mumol (10.5 mg) pure acetylsalicylic acid or 66 mumol (9.1 mg) salicylic acid to six volunteers and recovered 77-80% in 24-h urine samples. Thus, urinary excretion is a valid indicator for intake of free forms of (acetyl)salicylic acid. To estimate the bioavailable salicylate contents of diets, we subsequently studied salicylate excretion in 17 volunteers from 14 countries and four continents who ate a wide variety of self-selected diets. Median 24-h urinary salicylate excretion was 10 mumol (range: 6-12 mumol). Values increased with the fiber content of the diet (r = 0.73), suggesting that vegetable foods are the main sources of salicylates. However, amounts of salicylates in a variety of diets are evidently low and probably insufficient to affect disease risk.