吃褐色海藻可能预防黑色素瘤

Clinical studies of brown seaweeds in healthy people

Accordingly, maybe another way to look at brown seaweeds and melanoma is a general picture of what whole seaweed does in healthy people and animals. We looked at healthy humans in several clinical studies and have found that the inclusion of 5 g day⁻¹ brown seaweed (Alaria esculenta and Undaria pinnatifia) was associated with changes in biomarkers found in melanoma (Teas et al. 2009; Teas et al. 2011; Teas et al. 2013). Fifteen healthy postmenopausal women consumed 5 g day⁻¹ placebo for a month, followed by 5 g day⁻¹Undaria for a month, followed by 5 g day⁻¹ of placebo for a month. The most profound change was a significant 50 % reversible reduction in urinary urokinase receptor (uPAR). In most cancers, patients with metastatic disease have increasing excretion of uPAR and this is prognostic of a rapidly progressing disease. uPAR is an important factor in inflammation, differentiation, proliferation, detachment from the extracellular matrix, and migration. Although we observed this change in healthy women, they were mostly overweight (average body mass index (BMI) of 30, which is the lower limit for being obese). Adipose tissue has been reported to be associated with an ongoing turnover of uPAR (Choe et al. 2016). However in terms of relevance to melanoma, in vitro and in vivo studies of reducing uPAR on the surface of tumor cells were associated with inducing a state of dormancy (Yu et al. 1997; Ossowski and Aguirre-Ghiso 2010; Noh et al. 2013). It remains to be seen if seaweed ingestion by melanoma patients could have a similar effect.

In a different study, we found a decrease in p-selectin plasma concentration. In a small pilot study of eight people challenged with a high fat breakfast with and without 5 g Undaria, we found that 4 h after eating that there was a significant difference in p-selectin. It was increased with placebo and decreased with seaweed (unpublished data, poster). For various reasons, this study was not repeated in a larger sample size, but a plethora of studies in animals have reported that dietary seaweed and its extracts decrease p-selectin (Fitton 2011; Fitton et al. 2015). Many cancer cells including melanoma tumor cells bind to p-selectin in the process of moving from one site to another. This effectively hides the tumor cells from the body’s immune attack and from the sheer stress of blood flow around them, increasing the likelihood of extravasation into new tissue sites for metastases.