Stinging nettle contains a wide range of phenols and polyphenols in the roots, stems, and leaves. Phenolic compounds, such as flavonoids, tannins, and lignans, are all present in stinging nettle and are thought to be largely responsible for the effects of stinging nettle supplements.[1]
In BPH, stinging nettle, particularly the root, disrupts the cells that need to proliferate to cause prostatic hyperplasia. This is as a result of nettle’s impact on androgens and their transport proteins, SHBG. Stinging nettle’s phenolic compounds may also lower the activity of enzymes in the cell walls of the prostate.[2][3]
In order to lower blood sugar, stinging nettle binds to intestinal receptors, lowering the absorption of glucose. It may also stimulate insulin secretion.[4][2] Further, stinging nettle may lower the synthesis of cyclooxygenases and prostaglandins, which are involved in inflammation and pain responses. It may also inhibit interleukin-1, and interleukin-2, and tumor necrosis factors, which are important for the inflammatory response.[2][5]
Nettle extract, especially from the leaves, may also have antioxidant properties. This is because of the phenolic compounds in the leaves, which help clear out reactive oxygen species.[2][1]
Stinging nettle may improve asthma and allergy symptoms as it blocks histamine receptors and lowers the release of cytokines involved in inflammation.[6][2]