Kate Middleton's beauty tip that Michelle Obama swears by

Now the secret behind the 52-year-old's youthful look has been revealed, and her fresh face is apparently thanks to a tip from the Duchess of Cambridge.

The First Lady's make-up artist Carl Ray says that Kate recommended £43 ($54) Biotulin Supreme Skin Gel to Michelle - a non-injectable "organic Botox".

"Michelle Obama has been using this organic Botox gel regularly on the recommendation of Kate Middleton," Carl told Celebrities Style, adding that it is "unbelievable" for erasing wrinkles.

The gel contains a natural local anesthetic extracted from the plant Acmella oleracea, which promises to reduce muscle contractions and relax the facial features around the eyes and between the eyebrows.

This promises to reduce fine lines and make the skin noticeably smoother.

It also contains extracts of Imperata cylindrica, a hardy grass that grows in South America's desert regions, which gives an intense moisturising effect.

The third key element is skin-plumping Hyaluronic acid to restore fullness to the face.

Biotulin claims to provide visible results in 60 minutes that last up to 24 hours.

Carl has previously revealed that Michelle likes to keep her skincare regime simple and natural, relying on exercise, plenty of water, a good diet and sleep to keep her glowing.

And the First Lady herself confirmed in an interview that she doesn't go in for a complicated regime.

"It's really pretty basic. I wash my face with a good cleanser, and I use a moisturizer with an SPF," she told Prevention.

"Every now and then I'll go to a dermatologist for microderm or a facial, but I don't have time to do that all the time."

The Duchess is also a fan of natural skincare and is reportedly a convert to Beuti Skincare's Beauty Sleep Elixir, which contains 14 plant-based oils that neutralise the enzymes that inflame and damage the skin.

- Daily Mail