Nature's Sunshine Fibralgia helps to support chronic muscle stiffness and fatigue, which may result in constant tension in muscles in the lower back, neck, shoulders, back of the head, upper chest and thighs. The reason for this may lie in the body's energy production system. If the body is deficient in energy-producing fuel, it breaks down muscle protein to create energy. Scientific studies have demonstrated that supplements containing malic acid and magnesium can provide some support, as both malic acid and magnesium play an important role in cellular energy production. Nature's Sunshine Fibralgia is formulated with 80mg Magnesium and 350mg Malic Acid per capsule