Why does orange juice taste bad after tooth brushing? © Getty Images

Why does orange juice taste bad after tooth brushing?

Brushing your teeth is great for your gnashers but not so much for your taste receptors. Sodium lauryl sulfate in toothpaste cuts sweetness and highlights natural bitterness.

Dr Emma Davies

Asked by: Nigel Ngwenya, Leeds

Toothpaste contains sodium lauryl sulfate (SLS) that creates bubbles when you brush. But it suppresses sweet receptors on the tongue, which prevents the brain from registering sweetness, and destroys compounds in the saliva called phospholipids, which block bitter receptors. So SLS not only cuts orange juice’s sweetness, but promotes its natural bitterness, too.

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Dr Emma Davies is a science writer and editor with a PhD in food chemistry from the University of Leeds. She writes about all aspects of chemistry, from food and the environment to toxicology and regulatory science.