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| Sixth taste discovered: calcium (image source: Dreamstime), Live Science |
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A while back my taster was off. No, not my personal wine taster or food taster, but my taste buds. One day I took a calcium tablet on a whim, and, voilà!, the taster was back on course.Wikipedia has a good article on taste. It name the five basic tastes: sweetness, sourness, saltiness, bitterness, and umami. Then adds a bit on other qualities that can be perceived:
The basic tastes contribute only partially to the sensation and flavor of food in the mouth—other factors include smell, detected by the olfactory epithelium of the nose; texture, detected through a variety of mechanoreceptors, muscle nerves, etc.; temperature, detected by thermoreceptors; and "coolness" (such as of menthol) and "hotness" (pungency), through chemesthesis.
But why calcium? It seems that in 2008 a sixth 'taste' was discovered: calcium. The research was conducted by Michael Tordoff, a behavioral geneticist at the Monell Chemical Senses Center in Philadelphia. He says about the taste of calcium:
"Calcium tastes calcium-y," Tordoff said. "There isn't a better word for it. It is bitter, perhaps even a little sour. But it's much more because there are actual receptors for calcium, not just bitter or sour compounds."
Apparently a taste receptor for calcium
... makes sense for our survival, since the mineral is key to cell biology and good bones. Low calcium intakes have been implicated in several chronic diseases in people, including osteoporosis, obesity and hypertension.
"Many animals have a specific calcium appetite, which implies they can detect the mineral and consume sufficient quantities of it to meet their needs," Tordoff said.
ScienceDaily also reported on this topic in That Tastes ... Sweet? Sour? No, It's Definitely Calcium!
In 2012 Nature published a scholarly article that essentially followed-up on the discovery. It is titled "T1R3: A human calcium taste receptor." While the article is fairly technical, it make a thought-provoding statement in the discussion:
We are often asked whether calcium is a basic taste, akin to sweet, sour, salty, bitter and umami. Our demonstration of a receptor in the oral cavity fulfills a universally accepted criterion for a basic taste but there is little consensus about what other criteria must be met. For example, is a specific taste quality or a central representation required? The “basic taste” concept is under fire. It cannot deal well with observations that the tastes of complex carbohydrates are bland to humans but avidly preferred by many other species, that dozens of receptors all produce a unitary sensation of bitterness, or that there is apparently no region encoding sour taste in primary taste cortex. Without a better definition we cannot determine whether calcium is a basic taste. Nevertheless, our results showing that calcium and lactisole interact with T1R3 establish T1R3 as a calcium taste receptor, and consequently provide the first evidence for calcium taste transduction in the human oral cavity.
-- Marge
