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Scientists at the Monell Chemical Senses Center (Philadelphia) have reported that bitter taste perception of vegetables is influenced by an interaction between variants of taste genes and the presence of naturally-occurring toxins in the vegetable. Scientists have long assumed that bitter taste evolved as a defense mechanism to detect potentially harmful toxins in plants. This study (which appears in the September 19 issue of Current Biology) provides the first direct evidence in support of this hypothesis by establishing that variants of the bitter taste receptor TAS2R38 can detect glucosinolates—a class of compounds with potentially harmful physiological actions—in natural foods.
Glucosinolates act as anti-thyroid compounds. The thyroid converts iodine into thyroid hormones, which are essential for protein synthesis and regulation of the body’s metabolism. Glucosinolates inhibit iodine uptake by the thyroid, increasing risk for goiter and altering levels of thyroid hormones. The ability to detect and avoid naturally-occurring glucosinolates would confer a selective advantage to the over 1 billion people who presently have low iodine status and are at risk for thyroid insufficiency.
Of the study, senior author and Monell sensory scientist Paul Breslin said, “The findings show that our taste receptors are capable of detecting toxins in the natural setting of the fruit and vegetable plant matrix…The sense of taste enables us to detect bitter toxins within foods, and genetically-based differences in our bitter taste receptors affect how we each perceive foods containing a particular set of toxins.”
Lead author Mari Sandell comments on additional nutritional and practical implications of the study, “Taste has a great impact on food acceptability and choice. A comprehensive understanding how food components contribute to taste is necessary to develop modern tools for both nutritional counseling and food development.”