Premium beverage company Bolthouse Farms is recalling approximately 3.8 million bottles of protein shakes because the products may be spoiled—causing the beverages to appear lumpy, taste unpleasant and have an off odor.

The California-based company—which is a leading carrot distributor in in addition to producing its smoothies, shakes, juices and dressings—says the problem was identified after the company received consumer complaints about the products, including reports of illness. The exact cause of the problem is currently under investigation.