Bitter taste identifies poisons in foods

September 18, 2006

Scientists at the Monell Chemical Senses Center report that bitter taste perception of vegetables is influenced by an interaction between variants of taste genes and the presence of naturally-occurring toxins in a given vegetable. The study appears in the September 19 issue of Current Biology.

Scientists have long assumed that bitter taste evolved as a defense mechanism to detect potentially harmful toxins in plants. The Current Biology paper 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.

"The findings show that our taste receptors are capable of detecting toxins in the natural setting of the fruit and vegetable plant matrix," said senior author Paul Breslin, a Monell sensory scientist.

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.

In the study, 35 healthy adults were genotyped for the hTAS2R38 bitter taste receptor gene; the three genotypes were PAV/PAV (sensitive to the bitter-tasting chemical PTC,) AVI/AVI (insensitive), and PAV/AVI (intermediate).

Subjects then rated bitterness of various vegetables; some contained glucosinolates while others did not. Examples of the 17 glucosinolate-containing vegetables include watercress, broccoli, bok choy, kale, kohlrabi, and turnip; the 11 non-glucosinolate foods included radicchio, endive, eggplant and spinach. Subjects with the sensitive PAV/PAV form of the receptor rated the glucosinolate-containing vegetables as 60% more bitter than did subjects with the insensitive (AVI/AVI) form. The other vegetables were rated equally bitter by the two groups, demonstrating that variations in the hTAS2R38 gene affect bitter perception specifically of foods containing glucosinolate toxins.

Together, the findings provide a complete picture describing individual differences in responses to actual foods at multiple levels: evolutionary, genetic, receptor, and perceptual. "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," summarizes Breslin.

Breslin notes, "The contents of the veggies are a double-edged sword, depending upon the physiological context of the individual eating them. Most people in industrialized cultures can and should enjoy these foods. In addition to providing essential nutrients and vitamins, many are reported to have anti-cancer properties."

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."
-end-
The Monell Chemical Senses Center is a nonprofit basic research institute based in Philadelphia, Pennsylvania. For 35 years, Monell has been the nation's leading research center focused on understanding the senses of smell, taste and chemical irritation: how they function and affect lives from before birth through old age. Using a multidisciplinary approach, scientists collaborate in the areas of: sensation and perception, neuroscience and molecular biology, environmental and occupational health, nutrition and appetite, health and well being, and chemical ecology and communication. For more information about Monell, please visit www.monell.org.

CITATION: Mari A. Sandell and Paul A.S. Breslin. Variability in a taste-receptor gene determines whether we taste toxins in food. Current Biology, 2006, 16, R792-R794.

FUNDING: National Institute on Deafness and Other Communication Disorders, National Institutes of Health

FOR FURTHER INFORMATION CONTACT: Leslie Stein, Monell Chemical Senses Center, 215.898.4982, media@monell.org

Monell Chemical Senses Center

Related Vegetables Articles from Brightsurf:

One third of UK fruit and vegetables are imported from climate-vulnerable countries
One third of UK fruit and vegetables are imported from climate-vulnerable countries - and this is on the rise.

Eating your vegetables is easier said than done
The landmark EAT-Lancet report on food in the Anthropocene sets ambitious targets.

Research shows that the combined production of fish and vegetables can be profitable
When it comes to future food production, the combined farming of fish and vegetables through aquaponics is currently a hotly debated topic.

Sensitivity to bitter tastes may be why some people eat fewer vegetables
A gene that makes some compounds taste bitter may make it harder for some people to add heart-healthy vegetables to their diet.

Flowering mechanism in Brassica rapa leafy vegetables illuminated
Post graduate students in Kobe University's Graduate School of Agricultural Science have revealed the role of genes in controlling flowering time in the Brassica rapa family.

Offering children a variety of vegetables increases acceptance
Although food preferences are largely learned, dislike is the main reason parents stop offering or serving their children foods like vegetables.

Cooking vegetables: healthier with extra virgin olive oil
Cooking vegetables in the sofrito (sauté) with extra virgin olive oil favours the absorption and release of bioactive compounds of its traditional ingredients (garlic, onion and tomato), according to the study published in the journal Molecules about the role of gastronomy in the health-improving effects of the Mediterranean Diet.

Millions of cardiovascular deaths attributed to not eating enough fruits and vegetables
Preliminary findings from a new study reveal that inadequate fruit and vegetable consumption may account for millions of deaths from heart disease and strokes each year.

Tuck into colourful fruits and vegetables and see the light
A $5.7 billion global medical bill to restore sight for the estimated 45 million people with cataracts could be slashed in half by a diet rich in colourful fruits and vegetables, according to an international study.

Canadians' consumption of fruit and vegetables drops 13 per cent in 11 years
Two surveys taken 11 years apart show a 13-per-cent decrease in the amount of fruit and vegetables being consumed by Canadians, new University of British Columbia research has found.

Read More: Vegetables News and Vegetables Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.