How Much Saw Palmetto Should You Take to Block DHT?

In men, the prostate is a gland the size and shape of a walnut that surrounds part of the urethra, and makes some of the fluid portion of semen. The prostate can enlarge and cause urinary problems in a non-cancerous condition called benign prostatic hyperplasia, or BPH. Enlarged prostate affects more than half of men older than 60, according to the National Kidney and Urologic Diseases Information Clearinghouse. An herbal remedy from the saw palmetto plant (Serenoa repens) may help improve this problem by reducing levels of a male hormone called dihydrotestosterone, or DHT, that's involved in BPH 5.

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Saw Palmetto

The saw palmetto plant produces small berries that contain several natural compounds with biological activity 5. These include a group of fatty compounds called plant sterols, such as beta-sitosterol, campesterol and stigmasterol. These compounds have anti-inflammatory activity, according to experts at Memorial Sloan-Kettering Cancer Center, and may also block the activity of a cellular enzyme called 5-alpha reductase 1. This enzyme converts the main male sex hormone, testosterone, into its metabolite, DHT. Although the cause of BPH is not totally understood, excess production of DHT in the gland is probably involved. Saw palmetto compounds may reduce the amount of DHT available to prostate cells by as much as 40 percent, according to Sloan-Kettering experts 15.

The Right Amount

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Saw palmetto is available at health-food stores as powdered berries in capsules, or as tinctures or extracts 5. For best results, choose standardized preparations that contain 85 to 95 percent fatty acids and sterols to minimize differences between batches. Although no minimum effective dose has been established, a dose of 160 milligrams taken twice daily produced positive results in clinical research studies, although it may take as long as 30 days for the supplement to be effective. Avoid consuming saw palmetto tea 5. Because many of its active components don't dissolve in water, the tea is likely ineffective for BPH.

Side Effects and Precautions

Although generally considered a safe supplement, saw palmetto might cause mild stomach upset or headache, and shouldn't be used by pregnant or breast-feeding women, or by anyone with or at risk of a hormone-related cancer 5. It has blood-thinning properties and could interact with anticoagulant drugs, and it shouldn't be combined with prescription anti-BPH medications. It could affect receptors, or cellular binding sites, for sex hormones, so don't take it with oral contraceptives or hormone replacement therapy. Discuss use of saw palmetto with your doctor to decide whether it's a good choice for you 5.

Research Evidence

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Some research suggests that saw palmetto compounds may be helpful in controlling DHT production in men who already have BPH 5. In one clinical study published in the May 2001 issue of "Urology," researchers measured DHT levels in prostatic biopsy specimens from men with BPH who took either a saw palmetto supplement or a placebo for six months 45. They found that DHT levels were reduced by 32 percent in the group taking saw palmetto, compared to the placebo group 5. A review of several clinical trials published in the summer 2001 issue of "Reviews in Urology" reported that saw palmetto compounds can suppress DHT production and might be able to improve symptoms of BPH, but also noted that results of clinical trials are mixed, concluding that more research is needed to confirm the herb's potential benefit 45.