Sea weeds are colonies of algae which possess some unique nutritional properties. For example, sea weeds contain the carotenoid fructoxanthin, sulphated polysaccharides such as laminarin and fucoidan, as well as a number of polyphenol compounds. Of particular nutritional interest is an insoluble indigestible fibre called alginate, that not present in land based plants. This fibre is known to directly affect gut bacteria, and is also able to bind to oestrogens in the intestinal tract. Some research has shown that sea weed is able to lower serum oestradiol in postmenopausal women, although it is not clear if this effect is due to the fibre or some other as yet unidentified anti-oestrogenic action. This oestrogen lowering effect is of interest because higher level of serum oestradiol are associated with an increased risk of developing breast caner.
Researchers1 fed 15 healthy women 7g/d of Alaria esculenta seaweed powder or a placebo for 7 weeks. There was then a 3 week washout period before the subjects crossed over to the other protocol. During the 7 week treatment or placebo period, the women consumed a soy protein isolate providing 2mg/kg body weight of isoflavones. The results showed there was an inverse correlation between the seaweed dose and the serum oestradiol, suggesting the seaweed had an anti-oestrogenic effect. Seaweed also increased excretion of equol, a non-steroidal oestrogen soy metabolite synthesised by colonic microflora. Evidence from other research suggests that Undaria seaweed is able to cause an 80% reduction in colonic β-D-glucuronidase activity, the enzyme needed to deconjugate oestradiol prior to enterohepatic recirculation. Alaria esculenta may therefore decrease serum oestradiol levels by preventing enterohepatic recirculation.
RdB
