The 62-year-old actress has been taking drops of Camu Gold – a vitamin C-laden liquid.
And she does not have to look far for the one-ounce bottles of the supplement, which is made from Camu Camu – a fruit that grows in the rainforest in Peru and Brazil.
The product is made by the Amazon Herb Company, which was founded by her husband John Easterling.
Newton-John, who is best known for playing Sandy in Grease, shamelessly plugged her husband’s health supplements during an appearance on a US chat show.
Asked about her marriage to Easterling, nicknamed Amazon John, she quickly piped up “I take his products” and pulled a bottle of Camu Gold from her pocket.
“It’s really delicious,” she told Wendy Williams, squirting a drop on the back of the host’s hand for her to try.
“It’s the highest concentration of vitamin C and it also helps with the uptake of serotonin and makes you feel good."
Newton-John secretly married Easterling in June 2008. The actress’s daughter Chloe was the only person who knew about the nuptials.