Brown kelp modulates endocrine hormones in female Sprague-Dawley rats and in human luteinized granulosa cells

Christine F. Skibola, John D. Curry, Catherine VandeVoort, Alan J Conley, Martyn T. Smith

Research output: Contribution to journalArticle

23 Scopus citations


Epidemiological studies suggest that populations consuming typical Asian diets have a lower incidence of hormone-dependent cancers than populations consuming Western diets. These dietary differences have been mainly attributed to higher soy intakes among Asians. However, studies from our laboratory suggest that the anti-estrogenic effects of dietary kelp also may contribute to these reduced cancer rates. As a follow-up to previous findings of endocrine modulation related to kelp ingestion in a pilot study of premenopausal women, we investigated the endocrine modulating effects of kelp (Fucus vesiculosus) in female rats and human luteinized granulosa cells (hLGC). Kelp administration lengthened the rat estrous cycle from 4.3 ± 0.96 to 5.4 ± 1.7 d at 175 mg · kg-1 body wt · d-1 (P = 0.05) and to 5.9 ± 1.9 d at 350 mg · kg-1 · d-1 (P = 0.002) and also led to a 100% increase in the length of diestrus (P = 0.02). Following 175 mg · kg-1 d-1 treatment for 2 wk, serum 17β-estradiol levels were reduced from 48.9 ± 4.5 to 40.2 ± 3.2 ng/L (P = 0.13). After 4 wk, 17β-estradiol levels were reduced to 36.7 ±2.2 ng/L (P = 0.02). In hLGC, 25, 50, and 75 μmol/L treatment reduced 17β-estradiol levels from 4732 ± 591 to 3632 ± 758, 3313 ± 373, and 3060 ± 538 ng/L, respectively. Kelp treatment also led to modest elevations in hLGC culture progesterone levels. Kelp extract inhibited the binding of estradiol to estrogen receptor α and β and that of progesterone to the progesterone receptor, with IC 50 values of 42.4, 31.8, and 40.7 μmol/L, respectively. These data show endocrine modulating effects of kelp at relevant doses and suggest that dietary kelp may contribute to the lower incidence of hormone-dependent cancers among the Japanese.

Original languageEnglish (US)
Pages (from-to)296-300
Number of pages5
JournalJournal of Nutrition
Issue number2
StatePublished - Feb 2005



  • Breast cancer
  • Estrogen
  • Fucus vesicutosus
  • Rat
  • Seaweed

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Food Science

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