Background
In TCM, "spleen" (pí) does not refer to the anatomical organ that sits under the left rib cage and filters blood. It refers to the functional sphere responsible for transforming food into usable substance and transporting that substance where it needs to go — in Western shorthand, it is closer to "digestive fire plus metabolic efficiency." When the spleen is weak, food doesn't transform properly (bloating, loose stools, poor appetite), energy doesn't generate efficiently (chronic fatigue), and dampness accumulates (a feeling of heaviness). Shenling Baizhu San is the canonical spleen-qi formula with a dampness-draining emphasis — "nourish the earth so the metal can breathe." Jianpi Wan addresses spleen weakness that has led to food stagnation. Xiangsha Liujun Wan adds qi-moving and dampness-transforming herbs to the basic spleen-tonifying structure, for when the stagnation is more about qi and phlegm than pure dampness. All three sit under the digestion concern, because the TCM "spleen" is primarily about what happens after you eat.