Bust-Enhancing Products

By Adriane Fugh-Berman, MD

Expensive "bust-enhancing" dietary supplements, sometimes in conjunction with topical creams, are being widely marketed. Whether or not bra cups are filled, wallets are emptied; a typical product costs $229 for an eight-week supply.

These products contain variable combinations of herbs, the most popular being hops (Humulus lupulus), saw palmetto (Serenoa repens), damiana (Turnera diffusa), dong quai (Angelica sinensis), chaste-tree (Vitex agnus-castus), blessed thistle (Cnicus benedictus), dandelion (Taraxacum officinale), wild yam (Dioscorea villosa), kava (Piper methysticum), fennel (Foeniculum vulgare), black cohosh (Actaea racemosa, syn. Cimicifuga racemosa), and fenugreek (Trigonella foenum-graecum).

Is there any reason to think that these products work? Web sites for these products are full of testimonials, but not one clinical efficacy trial has been published. Nevertheless, it is plausible that some of these combinations may have an effect; some of these herbs are hormonally active and it is conceivable that a combination could exert a sufficient pharmacological effect to cause mammoplasia (breast enlargement in women).

Estrogenic Herbs

Estrogens are known to increase breast size; some women notice this effect with birth control pills. Phytoestrogens are much weaker than endogenous estrogens, but there is a broad range of activity among phytoestrogens. Although genistein and daidzein present in beans may be considered safe, the long-term safety of other phyto-estrogens has not been established. Herbs that may have estrogenic effects include hops, fennel, and black cohosh.

Hops: Several herbal products promoted for bust enhancement are based on or contain hops, which contain 8-prenylnaringenin, an unusual and potent phytoestrogen that may be topically absorbed (see accompanying hops article).

Fennel: Fennel is estrogenic in animal studies. In female rats, oral administration of fennel seed acetone extract for 10 days caused vaginal cornification and estrus. Moderate doses increased the weight of mammary glands; higher doses increased the weight of oviduct, endometrium, myometrium, cervix, and vagina.1

Black cohosh: Several studies have found that black cohosh decreases hot flashes. Reduction of hot flashes is usually, although not always, an estrogenic effect; in vitro and in vivo studies of estrogenicity are mixed (see Alternative Therapies in Women’s Health November 2001). Black cohosh does not appear to contain the phytoestrogen formononetin,2 but it does contain a more recently identified phytoestrogen, fukinolic acid (2E-caffeoylfukiic acid),3 which has shown estrogenic activity in a breast cancer cell line and increased uterine weight in rats.

Other Hormonally Active Herbs

Saw palmetto: Used to treat benign prostatic hypertrophy (BPH), saw palmetto inhibits binding of dihydrotestosterone to androgen receptors in prostate cells (specifically the cytosol) and inhibits binding of [3H] DHT to its receptor in human foreskin fibroblasts.4 Saw palmetto also inhibits prolactin5 and has potent a1-adrenoceptor effects in vitro.6 Studies are mixed on whether saw palmetto inhibits 5a-reductase.7-9

An anti-estrogenic effect was noted in a placebo-controlled trial of 35 men with BPH who received S. repens 160 mg bid.4 If saw palmetto inhibits the conversion of testosterone to dihydrotestosterone, it is possible that a higher testosterone:dihydrotestosterone ratio increases the susceptibility of the breast to estrogenic action. A higher testosterone:dihydrotestosterone ratio has been linked to spontaneous gynecomastia in adolescent males.10

In women, increasing free testosterone levels may be detrimental; elevated free testosterone has been associated with increased breast cancer risk.11

Kava: Kava may have dopamine antagonist effects; acute dystonic reactions have been reported in three cases.12 Dopamine antagonists increase prolactin secretion, which may be associated with mammoplasia. An observational study in 59 women treated with selective serotonin reuptake inhibitors (SSRIs) or venlaxafine for more than two months found that 23 of 59 (39%) reported some mammoplasia.13 The effect was more common with SSRIs and was associated with weight gain. Serum prolactin increased significantly among those who used paroxetine.

Chaste-tree: Chaste-tree berry decreases follicle-stimulating hormone, increases luteinizing hormone, and inhibits prolactin activity in vitro. None of these effects should be associated with mammoplasia.

Other Herbs

Wild yam and fenugreek: Both wild yam and fenugreek contain diosgenin, which can be converted to progesterone in the laboratory; there is no evidence that such conversion takes place endogenously.

There is no evidence that diosgenin increases breast size. An article provided by one company as evidence that diosgenin increases mammary size actually states no such thing. This experiment, in which 20 or 40 mg/kg diosgenin was given with or without estrogen to ovariectomized mice, found no difference in wet or fat-free dry weight of mammary glands in diosgenin-treated mice.14 Diosgenin did significantly affect mammary maturation, increasing terminal end bud differentiation (an effect that takes place in late pregnancy or under estrogen treatment). Although the words "growth stimulator" and "mammary development" are used, in this case maturation is what is meant.

Roasted fenugreek seeds reputedly were used by harem women to enhance buxomness.15

Dong quai: A Chinese herb used in many women’s formulas, dong quai has been tested for hot flashes in a randomized, double-blind clinical trial; there was no effect on hot flashes, vaginal mucosa, or endometrium.16 There is a report of dong quai-associated gynecomastia in a man in Singapore;17 however, the product was not analyzed, and may have been adulterated with drugs.

Damiana: Traditionally used as an aphrodisiac, damiana is thought to be safe; however, little information is available on it.

Dandelion: Dandelion increases bile flow in animals and may have a diuretic effect;18 there is no evidence of a hormonal effect, nor is it used traditionally for hormonal effects.

Blessed thistle: No relevant information was identified for blessed thistle. High doses (> 5 g/cup of tea) can cause gastric irritation or vomiting.19


Drugs associated with gynecomastia or mammoplasia include estrogen, protease inhibitors, penicillamine, neuroleptics, tricyclic antidepressants, monoamine oxidase inhibitors, and serotonin reuptake inhibitors.13 Products marketed for bust enhancement contain hormonally active herbs that may have pharmacological effects. Hops, fennel, and black cohosh contain recently identified phytoestrogens; saw palmetto may increase free testosterone levels; and kava may increase prolactin—all actions that may affect the breast.

There are no long-term safety data on any of these herbs, singly or in combination. Estrogenic stimulation could potentially increase the risk of endometrial or breast cancer. Given that these products are aimed at young women, effects on fertility or fetal effects are also of concern. If a product increases breast size, it is active enough to raise concern about long-term adverse effects.


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3. Kruse SO, et al. Fukiic and piscidic acid esters from the rhizome of Cimicifuga racemosa and the in vitro estrogenic activity of fukinolic acid. Planta Med 1999; 65:763-764.

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13. Amsterdam JD, et al. Breast enlargement during chronic antidepressant therapy. J Affect Disord 1997; 46:151-156.

14. Aradhana, et al. Diosgenin—a growth stimulator of mammary gland of ovariectomized mouse. Indian J Exp Biol 1992;30:367-370.

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17. Goh SY, Loh KC. Gynaecomastia and the herbal tonic "Dong quai." Singapore Med J 2001;42:115-116.

18. Taraxaci folium (dandelion leaf) and Taraxaci radix (dandelion root) ESCOP Monographs on the Medicinal Use of Plant Drugs. Fascicule 2. Exeter, UK: European Scientific Cooperative on Phytotherapy; 1996.

19. McGuffin M, et al, eds. American Herbal Products Association Botanical Safety Handbook. Boca Raton, FL: CRC Press; 1997.