a To construct this table, substances were considered that are structurally, taxonomically, and functionally related to saw palmetto fruit, extracts saw palmetto fruit, or their constituents (see Table A). Only the substances considered to be relevant to the risk of saw palmetto as a dietary supplement are included in the table. “Functionally related” substances may exhibit an activity that saw palmetto exhibits, based on in vitro or other data; they are not listed here because they have a similar chemical composition
b Botanical ingredients in dietary supplements with uses similar to extracts of saw palmetto fruit were considered. No data suggestive of toxicity are available and thus these substances were omitted from this table. The following substances were considered: extract of African palm tree bark (Pygeum africanum); extract of bark or leaves of aspen trees (Populi tremula); goathead vine (Tribulus terrestris); pumpkin seed (Cucurbita pepo; whole seeds, coarsely ground seeds or extract of seeds); extract of rhizomes/root purple coneflower (Echinacea purpurea); extract of stinging nettle root (Urtica dioica) (should be avoided by pregnant women) (Peirce, 1999).
c SPES® (Botanic Labs, Brea CA), a blend of 15 botanical ingredients, was also considered but was not included in this table because it is not related to saw palmetto. Three of the ingredients of SPES are also in PC SPES® (a saw palmetto-containing blend of 8 botanicals); however, SPES does not contain saw palmetto. Additionally, SPES is used for cancer, not BPH. PC SPES is used in prostate cancer and BPH. The ingredients of PC SPES are described in a footnote to Table B-2. The ingredients of SPES are as follows: licorice (rhizome/root of Glycyrrhiza glabra Fisch/Glycyrrhiza uralensis Fisch, gan-zao), blushred rabdosia (leaf of Rabdosia rubescens Hara, dong-ling-cao), ginseng (root of Panax pseudoginseng Wall, jensheng), reishi mushroom (stem of Ganoderma japonicum, ling-zhi), desert ginseng (Cistanche deserticola, cheng-min chou), pear-leaf wintergreen (Pyrola rotundifolia L., lu-ti-cao), hairy agrimony (Agrimonia pilosa Lebed/Agrimonia japonica, xian-he-cao), yenhusuo/yan-hu-so (Corydalis yanhusuo/Corydalis bulbosa), higanbana/red spider lily (Lycoris radiata, shi-suan), mou-hui tou (Patrinia heterophylla), di-bu-long (Stephania delavayi Diels), runan/shan-wugui (Stephania sinica Diels, hua-jian-jiu-teng), golden cow in the soil/prickly-ash (Zanthoxylum nitidum, liang-mian-zhen), rokujo (Cervus nippon Temminck, lu-jung), and pollen (huafeng) (Fang and Wang, 1995). SPES may also contain soy milk. During analysis of specific lots of SPES substantial amounts of a synthetic drug (alprazolam, Xanax®) were identified (California Department of Health Services, 2002). SPES is no longer available on the market in the United States.
d Steroid 5-α-reductase inhibitors include: finasteride (Proscar®, MK-906; competitive inhibitor, selective inhibitor of human type 2 steroid 5-α-reductase, 50-fold selectivity), dutaseride (Duagen, GI-198745; inhibitor of human type 1 and type 2 steroid 5-α-reductase), epristeride (SKF 105657, a 3-androstene-3-carboxylic acid; uncompetitive inhibitor; selective inhibitor of human type 2 steroid 5-α-reductase, 400-fold selectivity), izonsteride (LY320236, a benzoquinolinone; competitive inhibitor of human type 1 steroid 5-α-reductase; noncompetitive inhibitor of type 2 steroid 5-α-reductase), and 4MA (N,N-diethyl-4-methyl-3-oxo-4-aza-5-α-androstane-17-β-carboxamide, a 3-oxo-4-aza steroid; potent inhibitor of type 1 and type 2 steroid 5-α-reductase; potent inhibitor of 3β-hydroxysteroid dehydrogenase). Type 2 steroid 5-α-reductase is the predominant activity in human prostate; rat prostate contains equal activity of type 1 and type 2 (Levy et al., 1994). DHT = dihydrotestosterone.