Seaweed accelerates the excretion of dioxin stored in rats

Oral Administration of Edible Seaweed Undaria Pinnatifida (Wakame) Modifies Glucose and Lipid Metabolism in Rats: A DNA Microarray Analysis

SCOPE

Wakame is an edible seaweed that is a common constituent in the Japanese diet. Previous studies showed that wakame consumption is associated with the prevention of metabolic syndrome, but the molecular mechanisms underlying the protective effects are poorly understood.

METHODS AND RESULTS

To determine if the expression of hepatic genes is affected by ingestion of the brown seaweed Undaria pinnatifida (wakame), rats were fed a diet containing 0, 0.1, or 1.0 g per 100 g dried wakame powder for 28 days. Administration of 1% wakame significantly decreased serum total cholesterol levels. Hepatic gene expression was investigated using DNA microarray analysis, and the results showed that wakame suppresses the lipogenic pathway by downregulating SREBF-1. Moreover, bile acid biosynthesis and gluconeogenesis were promoted by upregulation of the PPAR signaling pathway, which leads to a reduction in the accumulation of cholesterol and promotion of β-oxidation.

CONCLUSIONS

These results suggest that wakame ingestion affects glucose and lipid metabolism by altering the expression of SREBF-1 and PPAR signal-related genes.

Studies on the expression of liver detoxifying enzymes in rats fed seaweed (Monostroma nitidum)

The expression level of phase I (CYP1A1 and CYP1A2) and phase II (GST, and UGT) enzyme-coded genes were measured in liver microsomes of 30 Sprague-Dawley rats fed sea weed (Monostroma nitidum). Quantitative and qualitative analysis of the detoxifying enzymes were investigated using reverse transcription polymerase reaction (RT-PCR) and real time polymerase reaction (Real-time PCR) techniques. The antioxidative properties of seaweed were screened and investigated for its hepatoprotective activity in rat. There was no significant induction of GSTYa1, GSTYa2, and CYP1A2. However, an M. nitidum diet was found to significantly increase UGT1A1 and UGT1A6 mRNA levels and to decrease CYP1A1 mRNA levels in rat liver. Structural studies confirmed the presence of sulfated polysaccharides in the seaweed samples. The results demonstrate the potential of seaweed as a natural source of sulfated polysaccharide substances with potential use in chemoprevention medicine.

Effect of chlorophyllin-chitosan on excretion of dioxins in a healthy man

We investigated the usefulness of chitosan and chlorophyllin-chitosan (chl-chitosan) administration for reduction of the body burden of environmental dioxins, including polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/ Fs) and coplanar polychlorinated biphenyls (Co-PCBs), by examining the excretion levels in the feces and sebum of a healthy man. The volunteer ate the same three meals every day during the 40-d experiment, which was composed of five phases (I-V) of 8 d each. In phase I (days 1-8), the volunteer was given only the basal diet. In phases II-V, 0.2 g of chitosan, 0.6 g of chitosan, 0.2 g of chl-chitosan, and 0.6 g of chl-chitosan, respectively, were administered immediately after each meal. We measured daily the amount of dioxins occurring in the feces and sebum during the last 5 d of each phase. The total toxicity equivalency (TEQ) of the dioxin in phases I-V were 27, 26, 38, 36, and 67 pg/d in the feces and 20, 19, 16, 16, and 14 pg/d in the sebum, compared with 74 pg/d in the food. The excretion of dioxins in the feces was significantly increased in phases III, IV, and V, being 140% (p < 0.05), 135% (p < 0.05), and 249% (p < 0.01) of the control level (phase I). Although the dioxin in the sebum was slightly decreased in phase V as compared with the control level, the total amount of excreted dioxin in feces and sebum was increased significantly in phase V, being 174% of the control level, which is almost the same level as that in the food. This indicates that chl-chitosan can prevent accumulation of dioxin, at least at the intake level of normal foods.

The effect of Fucus vesiculosus, an edible brown seaweed, upon menstrual cycle length and hormonal status in three pre-menopausal women: a case report

BACKGROUND

Rates of estrogen-dependent cancers are among the highest in Western countries and lower in the East. These variations may be attributable to differences in dietary exposures such as higher seaweed consumption among Asian populations. The edible brown kelp, Fucus vesiculosus (bladderwrack), as well as other brown kelp species, lower plasma cholesterol levels. Since cholesterol is a precursor to sex hormone biosynthesis, kelp consumption may alter circulating sex hormone levels and menstrual cycling patterns. In particular, dietary kelp may be beneficial to women with or at high risk for estrogen-dependent diseases. To test this, bladderwrack was administered to three pre-menopausal women with abnormal menstrual cycling patterns and/or menstrual-related disease histories.

CASE PRESENTATION

Intake of bladderwrack was associated with significant increases in menstrual cycle lengths, ranging from an increase of 5.5 to 14 days. In addition, hormone measurements ascertained for one woman revealed significant anti-estrogenic and progestagenic effects following kelp administration. Mean baseline 17beta-estradiol levels were reduced from 626 +/- 91 to 164 +/- 30 pg/ml (P = 0.04) following 700 mg/d, which decreased further to 92.5.0 +/- 3.5pg/ml (P = 0.03) with the 1.4 g/d dose. Mean baseline progesterone levels rose from 0.58 +/- 0.14 to 8.4 +/- 2.6 ng/ml with the 700 mg/d dose (P = 0.1), which increased further to 16.8 +/- 0.7 ng/ml with the 1.4 g/d dose (P = 0.002).

CONCLUSIONS

These pilot data suggest that dietary bladderwrack may prolong the length of the menstrual cycle and exert anti-estrogenic effects in pre-menopausal women. Further, these studies also suggest that seaweed may be another important dietary component apart from soy that is responsible for the reduced risk of estrogen-related cancers observed in Japanese populations. However, these studies will need to be performed in well-controlled clinical trials to confirm these preliminary findings.