The Dual Medicinal and Edible Value of Corn Silk
Corn silk is the style and stigma of Zea mays L. of the Gramineae family. It is produced in most regions of the world; anyone who has grown or bought corn is familiar with it. Corn silk can be eaten as well as used medicinally, and it is one of the medicinal-edible varieties recorded in the Pharmacopoeia Standards of the Ministry of Health of the People's Republic of China (1985 edition). The US Food and Drug Administration has also confirmed that corn silk is safe and non-toxic. This material is collected in summer and autumn when corn matures; impurities are removed, and it is used fresh or dried in the raw form.
Corn silk is a diuretic and swelling-reducing herb commonly used in TCM clinics. TCM holds that corn silk is sweet and neutral, entering the Bladder, Liver, and Gallbladder meridians. It has the effects of promoting diuresis and reducing swelling, and clearing the liver and benefiting the gallbladder. It is often used to treat nephritic edema, diabetes, gallstones, ureteral stones, beriberi, urethritis, cystitis, and jaundice hepatitis. Folk use focuses mainly on corn silk's blood-sugar-lowering and diuretic, swelling-reducing effects, and scholars at home and abroad have done much research in this area.
Modern pharmacology has confirmed that corn silk has a strong diuretic effect and can also inhibit protein excretion, so it is especially suitable for nephritis patients with elevated urine protein. When treating nephritic edema, corn silk can be used alone or together with Yi Mu Cao (Leonuri Herba) and Che Qian Cao (Plantaginis Herba).
Corn silk also promotes bile secretion and reduces bile viscosity and bilirubin content. It has a therapeutic effect on cholecystitis and cholesterol stones. TCM holds that corn silk benefits the gallbladder and relieves jaundice, which may be mainly related to its promotion of bile secretion and reduction of bile viscosity.
Corn silk can also increase prothrombin content and platelet count in the blood, accelerate blood coagulation, and increase hemoglobin. According to this effect, corn silk can also be classified as a TCM blood-tonifying and hemostatic herb, especially suitable for cancer patients with low platelets and hemoglobin after radiotherapy and chemotherapy.
In recent years, the health benefits of corn silk have increasingly gained favor at home and abroad. Some scholars have also studied its antibacterial and anti-cancer effects. Although the research is not yet deep, corn silk's antioxidant, anti-tumor, blood-sugar-lowering, and lipid-lowering effects have been verified in animal experiments.
Corn silk is also very nutritious. The ketone compounds in corn silk are even more than ten times higher than in corn kernels. Corn silk is also rich in carbohydrates and various trace elements, especially potassium. Most of the diuretic drugs currently used in both Chinese and Western medicine cause potassium loss from the body; excessive potassium loss leaves patients with weak, lifeless legs. Corn silk, however, not only promotes diuresis and reduces swelling but also supplements potassium, and can be used in large doses, so it is superior to most diuretic, swelling-reducing herbs.
At present, we humans mostly treat corn silk as waste, which is truly a waste of resources. Corn silk is a natural free-radical scavenger, and all free-radical scavengers have anti-cancer effects. In recent years many scholars have conducted in-depth research on corn silk's free-radical-scavenging and antioxidant effects, and researchers at home and abroad hope to develop new drugs from corn silk extracts to treat liver damage, diabetes, and cancer.
TCM has used corn silk to treat disease for hundreds of years. The earliest record of its medicinal value is the Diannan Bencao. The Diannan Bencao holds that corn silk “is sweet in taste, slightly warm in nature, enters the Yangming Stomach meridian. It broadens the intestines and descends qi; it can treat women's breast lumps with redness and swelling, blocked milk flow, red swelling and pain, chills and fever, headache and bodily heaviness.” According to this record, corn silk also has the effect of treating acute mastitis.
The Lingnan Caiyao Lu records that decocting corn silk with pork can treat diabetes and also treat ℌpainful dribbling of urine with sand” (urethral stones). Folk use of corn silk mostly involves decocting a large amount of it (up to 1–5 liang) into a thick broth to drink as tea. In addition, folk use corn silk to treat ascites from schistosomal liver cirrhosis: 30–60 g of corn silk, 30 g of Chi Xiao Dou (Phaseoli Radiati Fructus), and 15 g of Dong Gua Zi (Benincasae Semen), decocted together for oral use.
Decocting corn silk to drink as tea can lower blood pressure, and is especially effective for renal hypertension. When corn silk treats nephritic edema and the secondary hypertension caused by it, it can address both the root and the manifestation. The Quanguo Zhongcao Yao Huibian also records that corn silk has the effect of preventing habitual miscarriage. Corn silk can be used to treat high blood sugar and lower-extremity edema that occur during pregnancy; because its nature is mild, it is very safe for pregnant women.
When corn silk is used medicinally, the dosage can be decided according to the severity of the patient's condition. If using a large dose of corn silk, consider first decocting the corn silk separately, then using its broth to decoct the other herbs; otherwise, the decoction from one dose would be too much for the patient to drink.
Personally, I suggest that cancer and diabetes patients can use corn silk as a dietary-therapy material and take it long term. Stewing meat with corn silk, or cooking corn silk together with Yi Yi Ren (Coicis Semen) into porridge, both work; one can also brew corn silk as tea, with a daily dose of up to 1–3 liang. Those with edema or abnormal liver function should especially persist with corn silk dietary therapy. When taking medicine long term, corn silk can also serve as a liver-protecting dietary regimen.