Natures Plus. KalmAssure .Magnesium Powder delivers 400 mg of natural, essential magnesium in highly bioavailable citrate form. Nature's Plus KalmAssure magnesium Powder delivers exceptional high-quality magnesium in a delicious drink mix. Feel the difference with Nature's Plus KalmAssure Magnesium Powder. Free from artificial colours and preservatives. Free from the common allerfens yeast, wheat, soya, and dairy.