She added: "I think happiness is the best tonic for keeping us youthful. Being happy with who you are inside radiates on the outside."
The oil is produced from nuts of the argan tree, which is native to Morocco and has long been used by Berber women to treat ailments such as dry skin, acne, wrinkles, joint pain and even stretch marks.
The traditional harvesting method involves letting goats eat the nuts, which are softer and easier to crack once they have passed through their gut.
However, the cosmetics industry has developed more modern extraction techniques. Experts say it contains twice as much vitamin E as olive oil and is rich in antioxidants. It also has anti-inflammatory properties that can help those with arthritis or rheumatism.
Roasted, it can be dipped in bread or drizzled on couscous and pasta and is credited with being able to lower cholesterol and ease arthritis. During the webchat, Zeta-Jones - married to Michael Douglas, 71 - also admitted women over 40 are sidelined by Hollywood movie bosses.
She said: 'I have been in this business since I was nine years old, and have heard the same thing said throughout the different parts of my career. Then, hello, I'm in my 40s... and it's true.'
She added: "There's talk in Hollywood about diversity right now, and it's a good conversation to be had, and necessary, but when we say diversity, let's mean diversity for actors with ethnic differences, age differences, and sex differences."
The actress said her two children - Dylan, 15, and 12-year-old Carys, are her greatest achievement.
"It was the best production I was part of, ever," she added.
- Daily Mail