Why Catherine plasters her hair in caviar at £200 a time

Catherine Zeta-Jones, it would seem, has a similar attitude to shampoo and conditioner.

While most of us have to make do with a handful of fragrant soapy foam, the Welsh actress smears on truffles and caviar.

At £200 a time, just for the fish eggs, looking good does not come cheap.

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There's something fishy here: Catherine Zeta Jones uses caviar to give her hair its noteworthy shine

But she credits the gourmet delights for giving her long brown tresses an unbeatable shine.

The Beluga caviar is apparently flown in from Iran five days ahead of her treatments at a beauty salon in South Kensington.

"Catherine discovered the caviar treatment last summer and was astounded by the difference it made to her hair," said a source.

"She has an incredibly rich and vibrant natural hair colour but the creamy, almost oily nature of caviar really brings this out, making the colour even richer and making it so much more glossy.

Husband Michael Douglas is also a fan of caviar, but he uses it for eating, not conditioning

"The eggs are packed with omega-3 fatty acids necessary for the formation of structural proteins. It is these proteins that repair dry and damaged hair and smooth over any split ends."

The two-hour pampering treatment at the celebrity salon, Hari's, also includes a complimentary glass of champagne and caviar canapÈs to nibble on.

Miss Zeta-Jones's hair is washed with a truffle-based shampoo, then smeared with the caviar, which is combed through and left to set.

The sturgeon roe are liquidised prior to use, which is said to remove any odour.

Unlike many fad treatments, caviar is actually proven to work as a conditioning therapy. The essential fatty acids it contains produce collagen and keratin, two proteins vital for the appearance of sleek hair.

Miss Zeta-Jones obviously feels the investment is worth it to keep one of her most celebrated assets in shape.

In 2005, the former Darling Buds Of May star was voted the celebrity with the "best dressed" hair in a nationwide survey by Sunsilk and London's City University.

It is not known what her husband, Michael Douglas, thinks of the beauty regime, but he is known to be partial to fish roe in its more traditional presentation.

At the couple's wedding seven years ago he ordered £12,000 worth of Beluga caviar to be served at the reception.