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WHY Are TOOTHPASTE AND ORANGE JUICE A Bitter COMBO?
By David Cruickshank
A lovely glass of orange juice at breakfast time is just the ticket to get you ready for the day. The vitamin C and zesty goodness make it the perfect morning beverage. However, sipping your OJ after brushing your teeth can be an eye-watering experience.
So what causes a delicious glass of orange to turn so bitter?
Well, the answer involves a common toothpaste ingredient called sodium lauryl sulfate or SLS for short.
Brushing our teeth with a toothpaste containing SLS temporally interferes with how our taste buds sense bitter and sweet.
The human mouth has evolved to have a sophisticated sensory system that can detect a broad spectrum of tastes. We have between 5000 and 10,000 taste buds all of which have 10 to 50 taste receptors allowing us to detect sweet, salty, bitter, sour and savory tastes.
When a food flavor triggers a reaction in a taste receptor it sends a message to our brains giving us vital information on what is being consumed.
Sodium lauryl sulfate throws a spanner in the workings of our sensory system by temporarily reducing the receptor’s ability to accurately detect certain tastes. After brushing our teeth with an SLS toothpaste our taste buds are less effective at detecting the sweetness of sugar but more sensitive to the bitterness of the citric acid in orange juice.
Also, SLS temporarily interferes with the cell components called Phospholipids that actively suppress sensations of bitterness. Without the full function of these phospholipids, we experience the uncensored bitterness of the citric acid in our orange juice.
Thankfully, the effect of SLS on our taste buds is short-lived and within half an hour our sense of taste will return to normal. To avoid spoiling the taste of your orange juice, brush your teeth and then wait about 30 minutes before breakfast. Alternatively, you can switch to an SLS-free toothpaste.
Apart from tampering with our taste buds, SLS has some other characteristics that have made it a highly controversial toothpaste ingredient. Up until recently, most kinds of toothpastes contained SLS, but due to much negative exposure in the media, many manufacturers now offer SLS-free options to cater for ingredient savvy consumers.
Our Authors & Contributors
Department of Electronics, Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 812-8581, Japan. [email protected]