Chocolate Peanut Butter Swirl SPIRU-TEIN Shake Product No. 45870 Rich in flavor and nutrition - thats SPIRU-TEIN! One of lifes true pleasures is enjoying a delicious treat you know is good for you in every way. Natures Plus is especially proud of its entire line of SPIRU-TEIN products. With zero fat, SPIRU-TEIN delivers a healthy infusion of plant-based protein, along with other essential nutrients.