Coix Seed (Yiyiren) Promotes Ovulation and Treats Infertility
Before the pandemic, a recovering female lung-cancer patient in her forties in Zhejiang accidentally became pregnant while taking a formula containing Coix seed (yiyiren). Yesterday (July 8, 2025), a 38-year-old recovering female sarcoma patient in Jiangsu told me she had also accidentally become pregnant recently. Neither had conceived for years, yet both became pregnant while taking the same formula containing Coix seed; this phenomenon interested me greatly.
In fact, under pharmacology item 8 of the "Yiyiren" entry in the Zhonghua Bencao (Chinese Materia Medica), there is this passage: "(Coix seed has) an ovulation-inducing effect; Coix-seed extract can induce ovulation in golden hamsters, the active substances being feruloyl stigmasterol and feruloyl campesterol. Clinically, patients with normogonadotropic hypogonadism show marked improvement in hypothalamic function after taking formulas based on Coix seed; anovulatory patients given Coix-seed preparations can be induced to ovulate." The literature source for this passage is: Kondo Y, et al. Chem Pharm Bull, 1988, 36(8):3147.
Yiyiren is the coix seed we commonly eat; it is the kernel of the grass plant Coix lacryma-jobi, sold in supermarkets, grain-and-oil shops, and wet markets across the country. It was used as a medicine by Chinese physicians as early as the Spring and Autumn and Warring States periods. The Shennong Bencao Jing records that Coix seed "mainly governs tendon tension and spasm, inability to bend and stretch, wind-damp bi, and downbears qi; prolonged use lightens the body and boosts qi."
Modern pharmacological research shows Coix seed has an anti-cancer effect and is also an effective anti-tumor promoter; ancient literature also records it can treat swelling toxins. The Yaoxing Lun, for instance, discusses its effects: "It can treat wind-heat and tendon tightness, and increases appetite; it mainly treats lung atrophy and lung qi, vomiting pus and blood, cough, nasal discharge, spittle, and upward qi flow; it breaks the five-stream toxin swelling." Coix seed can also treat rheumatic pain, beriberi, flat warts, and edema. Of course, today Coix seed is best known to the public for weight loss; many people use coix-seed-and-red-bean porridge or soup to lose weight.
The reason the two female patients' formulas contained Coix seed was mainly anti-cancer, yet both accidentally became pregnant, suggesting that Coix seed may also have acted for them to promote ovulation and conception. Coix seed is not yet widely used to treat female infertility, which is somewhat regrettable. Coix seed is a food, non-toxic and side-effect free, so for infertile women eating it is always better than taking drugs. Of course, the two patients' formulas also contained other ingredients, in the ratio raw Huangqi : Yiyiren : Huangjing : Danggui = 10:10:3:2; whether the other drugs played a synergistic role remains to be studied.
The passage above from the Zhonghua Bencao on Coix seed's functions also mentions that Coix seed can markedly improve hypothalamic function. The hypothalamus is a small but powerful region of the brain, situated below the thalamus and weighing only about 4 grams. As the "command center" of the nervous and endocrine systems, the hypothalamus directly influences body temperature, hunger, sleep cycles, emotional responses, and other physiological activities by regulating hormone secretion, maintaining internal homeostasis, and controlling the autonomic nervous system.
TCM also uses Coix seed to lower body temperature; for instance, the famous TCM fever-reducing formula "Sanren Tang" heavily doses Coix seed. Given Coix seed's such marked effect on the hypothalamus, it might also improve symptoms of emotional instability.