A powdery substance made of dried up algae may have been the cause of violent gastrointestinal distress reported by Soylent powder and bar consumers.

Company founder and CEO Rob Rhinehart told Bloomberg Monday that Soylent will release newly formulated products next year that “will no longer contain algal flour.”

As Ars reported last month, the company halted sales of its flagship 1.6 powder and its snack bars after reports of illnesses bubbled up online. The company said it had ruled out contamination or quality control problems and suspected that a poorly mixed ingredient was causing intolerances in some customers. In an October 27 blog post, the company said it had narrowed down suspects by identifying ingredients used in both 1.6 and the bars but absent from its other, issue-free products.

The company did not reply to Ars’ requests for followup information on what those ingredients might be or how the products would be quickly reformulated. Based on the ingredient lists, suspect ingredients included Isomaltooligosaccharide (a non-digestible, low-calorie sweetener made of short-chain carbohydrates), soy protein isolate, and whole algal flour.

A source close to the company previously told Ars that Soylent believed the soy protein was behind the gastrointestinal distress, which generally involved nausea, vomiting, and diarrhea shortly after eating one of the products. Soy is a known allergen, and the source noted to Ars that Soylent was using a poorly blended mixture of three types of soy proteins in its bars. However, many customers insisted that they had no issues with other soy-containing foods, including other Soylent products.

The algal flour is more of an unknown. It’s a pale yellow to green powder made of dried algae—specifically, Chlorella protothecoides strain S106, which is grown in vast fermentation tanks under controlled conditions and produced by TerraVia Holdings, Inc. under the product line "AlgaVia." The flour only achieved approval for use in foods by the Food and Drug Administration in December of 2014. The agency signed off that it was a Generally Recognized as Safe (GRAS) ingredient after reviewing industry-supplied data on its safety. In the original submission (PDF) to the FDA, the authors noted that participants in several small human trials of algal flour reported gastrointestinal upset, including nausea, cramping, and “bulky stools.”

The GRAS approval process has been under fire in the past for being too lenient with food manufacturers. In a 2013 comprehensive report on food additives, Pew Charitable Trusts concluded that the FDA’s regulatory process is “plagued with systemic problems” that allow for unchecked conflicts of interests, and that allowed some manufacturers to make GRAS decisions without even notifying the FDA. Pew estimated that around 1,000 chemicals used in foods have not been reviewed by the FDA.

In an e-mail to Bloomberg, TerraVia Senior Vice President Mark Brooks insisted that the algal flour is safe, writing: “Our algal flour has been used in more than 20 million servings of products, and we are aware of very few adverse reactions. In no cases was algal flour identified as the cause.”

According to a tip from Soylent user Raylingh, who has been closely tracking illnesses linked to Soylent products, there have been similar online reports linking another product containing algal flour, VeganEgg, to gastrointestinal distress. In vegan forums and on Reddit, consumers have complained of cramping and vomiting after eating the product.