Revealed: Why toothpaste ruins the taste of food

Ever wondered why a drink of sweet orange juice turns horribly bitter after brushing your teeth?

According to experts, the sensation is down to a specific chemical, known as sodium lauryl sulphate (SLS), a detergent commonly found in toothpaste.

This detergent specifically suppresses sweet taste receptors on the tongue, and destroys compounds designed to inhibit bitter sensations.

The chemical analysis was carried out by researchers from the American Chemical Society in Washington.

In a video, the scientists explained millions of people have experienced the unpleasant combination of brushing their teeth before reaching for a glass of orange juice, only to find the taste is more bitter lemon than sweet orange.

They added that the typical human mouth has more than 10,000 taste buds and 100 taste receptor cells.

These are designed to detect five different types of taste – sweet, sour, bitter, salty and the newly recognised umami, or savoury.

Toothpaste has four main ingredients, which give the paste its consistency.

Water adds body, abrasives help get rid of plaque, fluoride prevents cavities and detergent makes it lather or bubble.

The most frequently used detergent in toothpaste is sodium lauryl sulphate (SLS), which has already been noted for its strange effect on the mouth’s ability to taste.

And now the new research has found that SLS suppresses sweetness taste receptor cells in the mouth.

It also destroys compounds in the mouth called phospholipids, which are designed to inhibit bitter taste receptors.

The study team said: ‘This opens up a clear pathway for bitter molecules to reach taste receptors in the mouth.

‘This is the most likely reason why orange juice turns from sweet to sour immediately after you brush your teeth.’

The findings were published in the American Chemical Society’s online video journal Reactions.

Toothpaste has four main ingredients, which give the paste its consistency (pictured). Water adds body, abrasives help get rid of plaque, fluoride prevents cavities and detergent makes it lather or bubble