Serenoa repens, commonly known as Saw palmetto is a herbal medicine with a long history of use. Traditionally, Saw palmetto was used as a treatment for urogenital irritations, impotence and male infertility. For these reasons it was prescribed as a male reproductive tonic, being referred to as the ‘Old Man’s Friend’ by the American Eclectic physicians.
Saw palmetto is a small palm tree native to the United States South Atlantic Coast and Florida, as well as Southern Europe and North Africa. It grows dense crowns of leaves with saw-like margins, and dark berries about the size of olives.
The ripe, dried berries of the Saw palmetto plant contain constituents such as short-chain fatty acids and volatile (essential) oils. Due to these constituents, the berries are used in the manufacture of herbal medicines and supplements rather than other parts of the tree.
Native Americans would eat the berries year-round for their supposed nutritional, aphrodisiac and cough-reducing properties.
How does Saw palmetto exert its effects on the body?
Saw palmetto’s main effects on the body include is its ability to support prostate health and healthy testosterone levels. Testosterone is the predominant circulating sex hormone in men and plays a crucial role in sexual performance, sperm health, lean muscle mass, bone health and more.
Around 10% of the testosterone produced by an adult man each day is converted to dihydrotestosterone (DHT) via the testes and prostate by a group of enzymes called 5-alpha reductase. DHT is a more active and potent form of testosterone – it stimulates the development of male characteristics and is thought to be responsible for the start of puberty in boys, causing the development of the genitals, deepening of the voice and the growth of pubic and body hair.
In some men and typically with age, 5-alpha reductase function can become impaired, meaning the conversion of testosterone to DHT increases. This can impact men’s health, particularly regarding the prostate, with prostate enlargement and urinary disturbances as common symptoms of increased DHT.
Saw palmetto has been shown to inhibit the activity of the enzyme group 5-alpha reductase, helping to prevent the conversion of testosterone to DHT, thereby promoting prostate health and circulating testosterone levels in the body!
- Braun, L., Cohen, M. (2015), Herbs and Natural Supplements, An evidence-based Guide to Practice, (4th ed.), Chapter: Saw palmetto, pp. 875-880, Churchill Livingstone, Elsevier.
- Durdiakova, J., Celec, P. (2017), Medical Aspects of the Treatment of Lower Urinary Tract Symptoms/Benign Prostatic Hyperplasia: 5-Alpha Reductase Inhibitors, Molecular and Cellular Mechanisms in Hormones, Brain and Behaviour (3rd Ed.), <https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/5-alpha-reductase>
- Thorne Research (1998), Monograph: Serenoa repens, Alternative Medicine Review (3):3, pp.229.