Goop is back the spotlight this week, with an advertising watchdog group blasting actress Gwyneth Paltrow's lifestyle company for making "unsubstantiated, and therefore deceptive, death and disease-treatment claims."

In an open letter published earlier this week, consumer watchdog group Truth in Advertising called on California consumer protection regulators to launch an investigation into the company's marketing claims "and take appropriate enforcement action."

The letter comes after the group conducted an investigation into the popular lifestyle site's marketing, with staffers reporting finding more than 50 instances in which the company claims or suggests its products can treat a variety of ailments, from crystals for female reproductive issues to stickers that "promote healing."

Goop regularly draws criticism for promoting questionable or controversial "alternative health" products. Earlier this year, U.S.-based Canadian gynecologist Jennifer Gunter blasted the company for a product called jade eggs, while another product (wellness stickers) claimed to comprise materials used by NASA was soundly debunked. The recurring criticism is part of Canadian Timothy Caulfield's bestselling celebrity health culture critique Is Gwyneth Paltrow Wrong About Everything?

In a statement to media outlets, a Goop spokesperson said the company is "receptive to feedback" and that it "responded promptly and in good faith to the initial outreach from representatives of TinA.... Unfortunately, they provided limited information and made threats under arbitrary deadlines which were not reasonable under the circumstances."

The statement also described the watchdog group's portrayal as "misleading and their claims unsubstantiated and unfounded."

Oscar-winning actress Paltrow, who serves as CEO of Goop, founded the company in 2008 as a newsletter for friends, featuring favourite recipes, shops and travel recommendations.