In a recent post on Gwyneth's website Goop, the All-Purpose Cleanser from Jessica’s company Honest Company barely received a C grade.
"Many of the 'clean' products I proudly use (and have even touted on goop) have turned out to be a product of marketing, rather than actually safe," Gwyneth wrote in the introduction to her recent newsletter, before adding that she has been re-evaluating several products which she uses around her home.
Gwyneth Paltrow and Jessica Alba
And it’s not the first time they pair have had harsh words for each other.
Whilst promoting her book, The Honest Life: Living Naturally and True to You, last year, Jessica was asked if it was in any way inspired by Gwyneth.
"Gwyneth Paltrow probably lives a very similar lifestyle, but I didn't grow up with a bunch of money, so my tips are much more grounded: repurposing things and making things at home," said Jessica.
Jessica Alba founded her company in January 2012, and has previously spoken of her love of leading a natural lifestyle.
"There is no slapping my name on it and getting money," the star declared in March as she shared her story with entrepreneurial-minded women at the NBC Universal Power of the Purse breakfast.
Jessica Alba and family
Jessica said that becoming a mother inspired her to create a non-toxic line for parents and kids. The actress admitted that she noticed during her first pregnancy that there was a lack of affordable, safe baby products.
Gwyneth and Jessica were most recently seen together at a baby shower for friend Gwen Stefani, which was held at the Wolfgang Puck dining room at the Hotel Bel Air.
Mum-of-two Jessica was spotted arriving at the shower in February bearing a gift – an organic diaper cake from her The Honest Company. The 'cake' was made up of real eco-friendly nappies, wipes, lotions and bubble bath.
Other guests at the shower included stylist Rachel Zoe and Nicole Richie.