Studie: Soyaprotein gjør menn til kvinner!



I en nylig studie fikk en gruppe menn som tok soyaproteintilskudd i 4 uker en ubehagelig overraskelse.

Proteintilskudd basert på melk (myse og kasein eller en kombinasjon) er det mest vanlige på markedet i dag. Av ulike grunner er det mange som velger soyaproteiner i stedet, enten fordi de har hørt det gir helsebringende effekter, eller fordi de har intoleranser for melkeprodukter (enten protein eller melkesukker). Denne studien viser at det kan være lurt å finne andre alternativer enn soya!

12 menn i alderen 25 til 47 år fikk tilskudd av et soyaproteinpulver, 56 gram per dag, i 4 uker. I løpet av denne perioden målte forskerne 20% og opptil 40% reduksjon i testosteronnivåene. I et tilleggsforsøk så man at soyaprotein aktiverte østrogen-reseptoren, noe som gjør det velegnet for kvinner i overgangsalderen, men kanskje ikke for menn som vil fortsette å være menn… Østrogen-agonister har forøvrig interesse i kreftbehandling, som nevnt i en bisetning i konklusjonen, noe vi ikke skal gå inn på her.
Heldigvis var alt tilbake til normalt 2 uker etter at forsøkspersonene avsluttet bruken av soyaproteintilskuddet.

Det skal sies at om man begrenser inntaket til 20-30g skal det ikke oppstå lignende bivirkninger, men det beste er nok å holde seg til melkebaserte proteintilskudd (eller M-Factor som er vårt vegetabilske proteintilskudd).

Cancer Epidemiology Biomarkers & Prevention 16, 829-833, April 1, 2007. doi: 10.1158/1055-9965.EPI-06-0882

© 2007 American Association for Cancer Research

Clinical and Biological Activity of Soy Protein Powder Supplementation in Healthy Male Volunteers

Susan Goodin, Francisco Shen, Weichung J. Shih, Nisha Dave, Michael P. Kane, Patrick Medina, George H. Lambert, Joseph Aisner, Michael Gallo and Robert S. DiPaola

Purpose: To determine if a commonly used soy protein supplement exhibits biological activity in vivo and in vitro, we evaluated an over-the-counter soy protein powder supplement using blood from healthy male volunteers and in an estrogen receptor in vitro assay.

Subjects and Methods: We recruited healthy male volunteers 18 years of age or older that were in good health. Treatment consisted of consuming two scoops (56 g) of pure soy protein powder (Puritan’s Pride, Oakdale, NY) daily for 28 days. Serum testosterone and luteinizing hormone (LH) levels were collected on days –7, 0, 14, and 28 of therapy, and day 42. A reporter estrogen receptor (ER) assay was used to determine the effect on ER-ß and ER- in vitro.

Results: Twelve subjects were enrolled with a mean age of 32.25 years (range 25 to 47). Serum testosterone decreased 19%(±22%) during the 4-week use of soy protein powder (P = 0.021) and increased within 2 weeks after we discontinued soy protein powder. Serum LH concentrations decreased during the 4-week use of soy protein powder then increased within 2 weeks after we stopped the soy protein powder, but the changes did not reach statistical significance (P = 0.20). Soy protein powder was found to induce agonist activity to ER-ß using a reporter estrogen receptor assay in yeast.

Conclusion: Soy protein powder decreases serum testosterone levels in healthy men and acts as an ER-ß agonist; the significance of this biological effect with respect to cancer prevention needs further study.

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One response to “Studie: Soyaprotein gjør menn til kvinner!

  1. Pingback: Alternativer til Herbalife. Billigere & Bedre!!! « Kenneth's Verden

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