Meeresalgen in der Prävention von Brustkrebs

Zusammenfassung

Epidemiologische japanische Studien aus den 1980er-Jahren wiesen nach, dass die Rate des prämenopausal auftretenden Brustkrebses in Japan im Vergleich zu westlichen Populationen bei einem Viertel lag, beim postmenopausal auftretenden Brustkrebs sogar nur bei einem Neuntel. Internationale Tumorregister aus den USA und Japan bestätigen, dass Brustkrebserkrankungen in westlichen Regionen sowohl in der Prämenopause als auch in der Postmenopause auftreten, während es diesen postmenopausalen Peak in Japan nicht gibt. Lebensstil beeinflussende Faktoren – vor allem die Ernährung mit Soja und Meeresalgen – scheinen in Asien einen entscheidenden Einfluss auf die deutlich geringere Entwicklung von Hormon-sensitiven Tumoren zu nehmen. Die hier präsentierten Pilotstudien zeigen, wie die Zufuhr von Soja in Kombination mit Meeresalgen den Östrogen- und Phytoöstrogenmetabolismus bei postmenopausalen gesunden westlichen Frauen in Richtung Brustkrebsprophylaxe positiv beeinflussen. Soja und Meeresalgen zeigen eine Tumor-protektive synergistische Wirkung in der Senkung postmenopausal hoher Östrogenspiegel im Serum, eine verbesserte Equol-Bildung als Schutz gegen Brustkrebs, eine günstigere antiöstrogen-wirkende Ausscheidung der Östrogen-Metabolite über den Urin sowie eine Reduktion des IGF-1-Wachstumhormons. Die Studien zeigen sehr eindrucksvoll Wege auf in der Prophylaxe von Brustkrebs für Frauen in westlichen Regionen, aber nach japanischem Muster.

Summary

Seaweed in the prevention of breast cancer

Epidemiological Japanese studies from the eighties show that the rate of premenopausal breast cancer in Japan came to one quarter of the rate in western populations and post-menopausal breast cancer was even as low as one ninth. Particularly evident are the differences in post-menopause during which breast cancer occurs very frequently in regions such as the USA. This peak, however, does not occur in Japan. These figures indicate that lifestyle factors mainly nutrition and associated genetic and epigenetic factors can lead to breast cancer or, vice versa, can provide extra protection. Traditional Asian nutrition including fermented soy and seaweed clearly plays a special role here.

Many studies confirm that in post-menopause high serum oestradiol levels are associated with an increased risk of breast cancer or its recurrence. Studies with Japanese postmenopausal women who had recovered from breast cancer demonstrated serum oestradiol levels three times lower than those of American women under the same conditions. Japanese women who eat traditional soy and seaweed products also demonstrate a two to threefold higher faecal excretion rate of 17ß oestradiol, which leads to the following conclusion: nutritional factors and their effect on intestinal microflora could have an impact on the high breast cancer rates and the differences in worldwide distribution. The dietary fibre of seaweed has a higher binding and excretion affinity for oestrogens than the fibre of terrestrial plants. A plausible mechanism for the influence of intestinal microflora on the development of breast cancer could therefore be explained by means of oestrogen metabolism in which the recirculation of oestradiol from the gastrointestinal tract is reduced by the consumption of seaweed.

Diet which includes brown seaweed has a positive effect on intestinal microflora, which is very likely connected to the enhanced conversion of phyto-estrogens from soy isoflavones. The role of seaweed as a prebiotic catalyst for stimulating protective effects in phyto-estrogen and estrogen metabolism are intriguing and, in this combination, can offer a new approach in the natural chemoprevention of breast cancer.

Schlüsselwörter

Meeresalgen - Alaria - Wakame - Brustkrebsprävention - Soja - fermentiertes Soja - Phytoöstrogene - Soja und Meeresalgen - asiatische Ernährung - Equol

Keywords

Seaweed - Alaria - Wakame - Breast cancer prevention - Soy - Fermented soy - Phytoestrogens - Soy and seaweed - Asian nutrition - Asian food - Equol

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