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Antioxidant capacity and lipophilic content of seaweeds collected from the Qingdao coastline.

Lipophilic extracts from 16 species of seaweeds collected along the Qingdao coastline were screened and evaluated for their antioxidant activities (AA) using the beta-carotene-linoleate assay system. The diethyl ether soluble extracts of all selected seaweeds exhibited various degrees of antioxidative efficacy in each screen. The highest antioxidant capacities among the tested samples were observed for Rhodomela confervoides and Symphyocladia latiuscula and were comparable with that of the well-known antioxidant butylated hydroxytoluene and greater than that of propyl gallate. The lipophilic content of all 16 samples and the chemical composition of 4 selected seaweeds, R. confervoidesand S. latiuscula, which had higher AA, Laminaria japonica, which had intermediate AA, and Plocamium telfairiae, which had lower AA, were analyzed by gas chromatography and gas chromatography-mass spectrometry, respectively. Fatty acids and alkanes were found. The present data indicated an increase in antioxidative property with increasing content of unsaturated fatty acid. The result of this study suggests that seaweeds can be considered as a potential source for the extraction of lipophilic antioxidants, which might be used as dietary supplements or in production in the food industry. This is the first report on the antioxidant activities of lipophilic extracts from seaweeds.

Alkanes↗

The rumen microbiology of seaweed digestion in Orkney sheep.

The microbial populations of the rumens of seaweed-fed and pasture-fed Orkney sheep were examined. The populations in the pasture-fed sheep were similar to those of other domestic ruminants fed on land plants, but those of the seaweed-fed animals showed major differences in the dominant species. Total ciliate populations were quantitatively similar, but in the seaweed-fed animals Dasytricha ruminantium was one of the most dominant species. No phycomycete fungi or cellulolytic bacteria were found in the seaweed-fed animals, and the bacterial population was dominated by Streptococcus bovis, Selenomonas ruminantium, Butyrivibrio fibrisolvens and lactate-utilizing species. Electron microscopy revealed that spirochaetes and an unidentified filamentous bacterium were probably of major significance in seaweed digestion. The ability of bacterial strains from both groups of animals to metabolize plant and algal constituents was examined.

Animals↗

Effect of processing on the microflora of Norwegian seaweed meal, with observations on Sporendonema minutum (Hoye) Frank and Hess.

Meal from the brown seaweed Ascophyllum nodosum (L.) Le Jol. is mainly used as an animal feed supplement. Since moist weed often develops a marked mold growth and since little was known about the microflora of seaweed meal, a cultural procedure was developed to enumerate the populations of bacteria, yeasts, and molds of seaweed meals manufactured by different drying processes. The microflora could be supported by a variety of media varying in levels of nutrition and in the source and concentration of salts. Fresh weed contained less than 10(3) bacteria and less than 10(2) yeasts and molds per g (dry weight). The type and extent of microbial populations in seaweed meal appeared to be dependent upon the method of seaweed drying. Rotary drum-drying at temperatures decreasing from 800 to 80 C maintained or reduced the microbial populations to 10(3) organisms per g (dry weight). Although meals with high nutritional quality can be obtained with warm air- or rock-dried weed, these conditions can also permit bacterial and mold development. Extended rock-drying in variable weather conditions and prolonged storage of moist weed, both of which decrease the nutritional quality, also lead to high bacterial numbers and to a marked development of the halophilic brown mold Sporendonema minutum which attained populations of 10(8) viable spores per g of dried weed. A poultry diet containing 5% badly molded weed had no apparent toxic or growth-depressing effect when fed to chicks.

Animal Nutritional Physiological Phenomena↗

Sulfated polysaccharides derived from dietary seaweeds increase the esterase activity of a lymphocyte tryptase, granzyme A.

Intake of sulfated polysaccharides, such as fucoidan or lambda-carrageenan extracted from seaweeds, has been shown to enhance immune responses, resulting in inhibition of tumor growth. However, little is known about the mechanisms by which these sulfated compounds mediate the enhancement. In the present study, we examined the effect of sulfated polysaccharides from seaweeds on esterase activity of a lymphocyte tryptase, granzyme A (GzmA), which is believed to induce the production of cytokines in a variety of cells. Inclusion of fucoidan (from Fucus vesiculosus) or lambda-carrageenan (from Gigartina aciculaire and Gigartina) in the reaction mixture increased the hydrolysis of Nalpha-benzyloxy-L-lysine thiobenzyl ester (BLT) by a recombinant rat GzmA in a concentration-dependent manner. Heparin, a sulfated polysaccharide from animal tissues, also increase the BLT hydrolysis, but the effect was less remarkable than those of the polysaccharides from the seaweeds. Hanes-Woolf analysis revealed that the enhancements in the presence of these sulfated compounds from the seaweeds were attributed to the increases in the affinity of the enzyme toward the substrate but not to those in the turnover rate. Chondroitin sulfate A, a sulfated polysaccharide found in animal and plant tissues, showed no positive effect on the hydrolysis. In the present paper, we propose that the enhancement of immune responses by intake of the sulfated polysaccharides from seaweeds can be partially accounted for by their direct effects on GzmA.

Animals↗

[Nutritional evaluation and physiological effects of edible seaweeds].

A review concerning nutritional and physiological properties of edible seaweeds is presented. Seaweeds are traditionally consumed in Asia as sea vegetables, but in Western countries they have been used as sources of gelling or thickening agents. From a nutritional point of view, they are low-calorie foods, with a high concentration of minerals (Mg, Ca, P, K and I), vitamins, proteins and undigestible carbohydrates, and a low content in lipids. Quality of protein and lipid in seaweeds is acceptable comparing with other diet vegetables mainly due to their high content in essential amino acids and their relative high levels of unsaturated fatty acids. Dietary fiber content range from 33% to 75% of dry weight, and mainly consist of soluble polysaccharides (range from 17% to 59%). Seaweeds constitute a source of dietary fiber that differ chemically and physicochemically from those of land plants and thus may induce different physiological effects. Referenced data indicate that algal dietary fiber may show important functional activities, such as antioxidant, antimutagenic and anticoagulant effect, antitumor activity, and an important role in the modification of lipid metabolism in human body. In conclusion, seaweeds have a high nutritional value, therefore an increase in their consumption, would elevate the foods offer to population.

Food Handling↗

Expanding the scope of precision editing in seaweeds through the application of a novel CRISPR-associated nuclease 12a-aligned CRISPR system in Ulva prolifera.

Seaweeds, such as the fast-growing green alga Ulva prolifera, can be harnessed as valuable marine crops. The lack of scalable genome-editing tools hampers functional genomics to explore and elucidate algal molecular pathways with industrial importance. Here, we expanded precision genome modification in seaweeds by successfully demonstrating gene editing with a transgene-free AT-rich-targeting CRISPR-associated protein (Cas) system in U. prolifera. By evaluating various delivery buffers, comparing different Cas systems, and optimizing incubation temperatures, we determined suitable conditions for more widespread applicability of a novel Cas12a-aligned ST8 editor. We obtained >50 ST8-mediated knockout mutants of a toxin-based endogenous marker gene, UpAPT, at 28 °C post-delivery incubations. Our work diversified the applicable genome-editing tools in seaweeds, advancing algal functional genomics and providing more strategies to precisely target unexplored seaweed resources.

Ulva↗

Removal of heavy metals from aqueous solution by nonliving Ulva seaweed as biosorbent.

The growth of dense green seaweed mats of Ulva spp. is an increasing problem in estuaries and coasts worldwide. The enormous amount of Ulva biomass thus becomes a troublesome waste disposal problem. On the other hand, it has been revealed that nonliving seaweed biomass, particularly brown seaweeds, has a high capacity for assimilating heavy metals. In this study, the possibility of using Ulva seaweed biomass as a biosorbent for the removal of heavy metals was examined. After processing, the biomass material was very easy to separate from the aqueous solution using a mesh. The sorption capacity of Cd on Ulva biomass increased upon pretreatment with alkali solution. The outstanding function of the biosorbent was demonstrated at around pH 8. On the basis of the Langmuir isotherms of Cd, Zn and Cu using the alkali-pretreated biomass, the parameters q(m) and b were determined to be within the narrow range of 60-90 mg/g and 0.03-0.04 L/mg, respectively, for each metal. Given the q(m) and b values, Ulva seaweed is a good biosorbent material for removing heavy metals. In an experiment using artificial wastewater containing Cd, Zn, Cu, Cr and Ni, it was possible to remove each metal simultaneously using Ulva biomass. Adsorption by Ulva biomass is effective for the removal of heavy metals from wastewater.

Adsorption↗

Galactolipids rather than phlorotannins as herbivore deterrents in the brown seaweed Fucus vesiculosus.

The first investigation of seaweed chemical defense against herbivores involved the brown seaweed Fucus vesiculosus and suggested defense via phlorotannins. The first demonstration of seaweed induction of secondary metabolites in response to herbivory also involved the genus Fucus and assumed a defensive function for phlorotannins. Many other investigations correlate herbivore feeding preference with changing levels of phlorotannins in this genus and others, but few directly test the effects of phlorotannins. No studies have assessed Fucus chemical defenses using bioassay-guided separation to investigate the complete complement of compounds deterring herbivores. We investigated the deterrence of F. vesiculosus chemical extracts using herbivore bioassays to guide our chemical investigations. Although crude extracts from F. vesiculosus strongly deterred feeding by the sea urchin Arbacia punctulata, phlorotannins from this extract did not deter feeding at 2x or 4x natural concentration by dry mass. Feeding deterrence was due to: (1) a polar galactolipid in the ethyl acetate-soluble extract, and (2) a non-phenolic compound, or compounds, in the water-soluble extract. Although this is the first evidence of galactolipids deterring herbivores, such defenses could be geographically and taxonomically widespread. The galactolipid we discovered in Fucus occurs in marine dinoflagellates, and a related metabolite that deters herbivory has recently been discovered in a tropical green seaweed. We were unable to identify the second deterrent compound, but deterrence occurred in a fraction containing carbohydrates, including sulfated sugars, but no phlorotannins. Given the polarity of these chemical deterrents, they could co-occur with and confound bioassays of phlorotannins if investigators test phlorotannin-containing algal extracts without further purification.

Animals↗

Dietary intake of seaweed and minerals and prevalence of allergic rhinitis in Japanese pregnant females: baseline data from the Osaka Maternal and Child Health Study.

PURPOSE: It may be worthwhile to assess the possible protective effect of the traditional Japanese diet on allergic disorders. This cross-sectional study investigated the relationship between dietary intake of seaweed, vegetables, fruit, antioxidants, fiber, and minerals and the prevalence of allergic rhinitis. METHODS: Study subjects were 1002 Japanese pregnant women. Allergic rhinitis (including cedar pollinosis) was defined as present if subjects had received drug treatment at some point during the previous 12 months. Information on dietary factors was collected by using a self-administered diet history questionnaire. RESULTS: Seaweed intake was associated independently with a decreased prevalence of allergic rhinitis. Significant inverse dose-response relationships were found between calcium and phosphorus intake and allergic rhinitis prevalence. There also was a tendency for an inverse association between magnesium consumption and allergic rhinitis. Additional adjustment for calcium or magnesium intake apparently did not influence the inverse association with seaweed consumption. Consumption of vegetables, fruit, vitamins C and E, fiber, and zinc showed no association with allergic rhinitis, whereas a significant positive relationship was observed between beta-carotene intake and allergic rhinitis. CONCLUSIONS: High dietary intake of seaweed, calcium, magnesium, and phosphorus may be associated with a decreased prevalence of allergic rhinitis.

Adult↗

Spectroscopic studies of the biosorption of gold(III) by dealginated seaweed waste.

Gold biosorption by dealginated seaweed waste has been studied to elucidate the mechanisms of metal uptake from solution. Dealginated seaweed was able to retain up to 1 mmol g(-1) of Au from solution at pH 3. FT-IR showed the presence of carboxylate groups on the surface of the biosorbent; however, the changes observed for the Au-bound samples suggested very little sorption to the carboxyl moieties. Colloidal Au formed on the surface of dealginated seaweed by reduction of Au(III) to Au(0) was observed using ESEM and four different types of particles were clearly identified. The Au distribution matched closely that obtained for S atoms indicating a possible link between these elements. EXAFS measurements showed that colloidal Au is present on the surface of the biosorbent. Evidence of gold reduction from Au(III) to Au(I) and Au(0) was also confirmed by the measured bond distances characteristic of the metal. The coordination number obtained by EXAFS indicated that approximately 75% of the Au on the sample was present in the colloidal form and the remaining Au was bound to S as nearest neighbor. The proposed mechanisms for Au removal from solution are reduction of Au species by components on the surface of the biosorbent to form colloidal metal followed by retention of the ionic Au(I) species at the sulfur containing sites. The results show that dealginated seaweed can be used for the cleanup of gold-containing effluents.

Adsorption↗

Seaweed accelerates the excretion of dioxin stored in rats.

To prevent health problems of humans exposed to dioxin, it is important to enhance the fecal excretion of dioxin stored in the body. The effects of seaweed such as wakame, hiziki, and kombu on the gastrointestinal absorption and reabsorption of 17 types of polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) congeners was investigated in Wistar rats. Rats were fed 4 g of the basal diet or a seaweed diet containing PCDD and PCDF standard solution [233 ng of toxic equivalents (TEQ)/kg of body weight] once during the experiment period. In the group fed the 10% wakame diet, the levels of fecal excretion of PCDD and PCDF congeners were higher (p < 0.01) from days 1 to 5 by 2.8-fold for 2,3,7,8-TCDD, by 4.0-fold for 1,2,3,7,8-pentaCDD, by 3.4-fold for 1,2,3,4,7,8-hexaCDD, by 3.2-fold for 1,2,3,6,7,8-hexaCDD, by 2.5-fold for 1,2,3,7,8,9-hexaCDD, by 1.7-fold for 1,2,3,4,6,7,8-heptaCDD, by 1.1-fold for 1,2,3,4,6,7,8,9-octaCDD, by 3.0-fold for 2,3,7,8-tetraCDF, by 3.7-fold for 1,2,3,7,8-pentaCDF, by 3.7-fold for 2,3,4,7,8-pentaCDF, by 3.2-fold for 1,2,3,4,7,8-hexaCDF, by 3.0-fold for 1,2,3,6,7,8-hexaCDF, by 3.2-fold for 1,2,3,7,8,9-hexaCDF, by 2.9-fold for 2,3,4,6,7,8-hexaCDF, by 1.6-fold for 1,2,3,4,6,7,8-heptaCDF, by 2.2-fold for 1,2,3,4,7,8,9-heptaCDF, and by 1.2-fold for 1,2,3,4,6,7,8,9-octaCDF than those of the basal group, respectively. Rats were fed 4 g of the basal diet containing PCDD and PCDF standard solution (2991 ng of TEQ/kg of body weight) once on day 1 and then place on the basal diet for 7 days. After 1 week, the rats were fed either the basal diet or seaweed diet from days 8 to 35. In the group fed the 10% wakame diet, the levels of fecal excretion of PCDD and PCDF congeners were higher (p < 0.01 or p < 0.05) during the period from days 8 to 35 by 1.7-fold for 2,3,7,8-TCDD, by 1.8-fold for 1,2,3,7,8-pentaCDD, by 2.0-fold for 1,2,3,4,7,8-hexaCDD, by 1.9-fold for 1,2,3,6,7,8-hexaCDD, by 1.6-fold for 1,2,3,7,8,9-hexaCDD, by 1.5-fold for 1,2,3,4,6,7,8-heptaCDD, by 2.0-fold for 2,3,4,7,8-pentaCDF, by 2.1-fold for 1,2,3,4,7,8-hexaCDF, by 1.9-fold for 1,2,3,6,7,8-hexaCDF, by 1.7-fold for 2,3,4,6,7,8-hexaCDF, by 1.5-fold for 1,2,3,4,6,7,8-heptaCDF, and by 1.9-fold for 1,2,3,4,7,8,9-heptaCDF than those of the basal group, respectively. These findings suggest that the administration of seaweed such as wakame is efficient in preventing the absorption and reabsorption of dioxin from the gastrointestinal tract and might be useful in treatment of humans exposed to dioxin.

Animals↗

Arsenic speciation in chinese seaweeds using HPLC-ICP-MS and HPLC-ES-MS.

Three common Chinese edible seaweeds, one brown (Laminaria japonica) and two red (Porphyra crispata and Eucheuma denticulatum), were examined for their total arsenic content. The As species were extracted with yields of 76.4, 69.8 and 25.0%, respectively. Anion-exchange and cation-exchange high-performance liquid chromatography (HPLC) in combination with inductively coupled plasma mass spectrometry (ICP-MS) were used for the separation of the different arsenic species in two of the three seaweed extracts (Laminaria and Porphyra). The main arsenic species in the algal extracts are arseno sugars, although it has been shown that the Laminaria seaweed contains significant amounts of dimethylarsinic acid (DMA). HPLC was coupled with electrospray mass spectrometry (ES-MS) for structural confirmation of the arsenic species. The mass spectrometer settings for the arseno sugars were optimised using standards. The conclusions drawn on the basis of HPLC-ICP-MS were confirmed by the HPLC-ES-MS data. The HPLC-ES-MS method is capable of determining both arseno sugars and DMA in the seaweeds. The unknown compounds seen in the HPLC-ICP-MS chromatogram of Laminaria could not be ascribed to trimethylarsenic oxide or tetramethylarsonium ion.

Arsenicals↗

Variability of iodine content in common commercially available edible seaweeds.

Dietary seaweeds, common in Asia and in Asian restaurants, have become established as part of popular international cuisine. To understand the possibility for iodine-induced thyroid dysfunction better, we collected samples of the most common dietary seaweeds available from commercial sources in the United States, as well as harvester-provided samples from Canada, Tasmania, and Namibia. Altogether, 12 different species of seaweeds were analyzed for iodine content, and found to range from 16 microg/g (+/-2) in nori (Porphyra tenera) to over 8165 +/- 373 microg/g in one sample of processed kelp granules (a salt substitute) made from Laminaria digitata. We explored variation in preharvest conditions in a small study of two Namibian kelps (Laminaria pallida and Ecklonia maxima), and found that iodine content was lowest in sun-bleached blades (514 +/- 42 microg/g), and highest amount in freshly cut juvenile blades (6571 +/- 715 microg/g). Iodine is water-soluble in cooking and may vaporize in humid storage conditions, making average iodine content of prepared foods difficult to estimate. It is possible some Asian seaweed dishes may exceed the tolerable upper iodine intake level of 1100 microg/d.

Cooking↗

Effects of a sodium-potassium ion-exchanging seaweed preparation in mild hypertension.

A nonpharmacological approach in the treatment of mild hypertension is often advocated. In an attempt to decrease sodium and increase potassium intake, sixty-two middle-aged patients with mild hypertension were given a potassium loaded ion-exchanging sodium-adsorbing potassium-releasing seaweed preparation (seaweed fiber, SF). The mean blood pressure (MBP), evaluated in a double-blind crossover manner with four weeks familiarization and wash-out periods, showed a significant decrease after four weeks on 12 and 24 g/day SF but not on 6 g/day or placebo treatment. Systolic blood pressure during submaximal exercise decreased on all three SF doses. The decrease in MBP appeared to be significantly higher in sodium-sensitive (11.2 mm Hg, P less than .001) than in sodium-insensitive (5.7 mm Hg, P less than .05) patients and was in salt-sensitive patients significantly correlated to the increase in plasma renin activity (PRA). The urinary sodium excretion decreased, the urinary potassium increased and the sodium/potassium urinary excretion ratio decreased, indicating that the decrease of MBP was dependent on the decreased intestinal absorption of sodium and increased absorption of potassium released from the seaweed preparation. A sodium-potassium ion-exchanging seaweed preparation is an effective means of decreasing sodium and increasing potassium intake, and may be used for antihypertensive treatment in mild hypertension.

Adult↗

Unveiling the Molecular Secrets of Seaweeds: A Comprehensive Review of Bioinformatics Applications in Algal Research.

Recent advances in high-throughput sequencing, bioinformatics, and multi-omics technologies have transformed seaweed research by overcoming long-standing challenges associated with complex genomes, diverse life cycles, and limited genomic resources. This review provides a comprehensive overview of bioinformatics approaches used to investigate seaweed genomics, transcriptomics, proteomics, metabolomics, microbiomes, and functional genomics, with emphasis on the computational tools and databases that support these analyses. Applications of bioinformatics in phylogenetics, drug discovery, microbiome characterization, and the development of biofuels, nutraceuticals, pharmaceuticals, and sustainable agriculture are also discussed. Particular attention is given to emerging strategies involving multi-omics integration, genome editing, artificial intelligence, machine learning, and synthetic biology that are reshaping seaweed research. The review further examines current challenges, including incomplete genomic resources, data standardization, and the need for experimental validation of computational predictions. Collectively, these advances highlight the growing role of bioinformatics in enabling systems-level understanding of seaweed biology and accelerating their translation into sustainable biotechnological and marine bioeconomy applications.

macroalgal genomics↗

Feeding preferences of the endemic gastropod Astraea latispina in relation to chemical defenses of Brazilian tropical seaweeds.

Seaweed preference by the Brazilian endemic gastropod Astraea latispina was examined in the laboratory to evaluate the role of secondary metabolites in determining food choice. Of three species of seaweeds examined, Plocamium brasiliense was highly preferred; less so were Sargassum furcatum and Dictyota cervicornis were preferred less. Extracts and/or pure major metabolites of the two potentially chemically-defended seaweeds (P. brasiliense and D. cervicornis) were tested as feeding deterrents against A. latispina. Algal extract assays demonstrated that three concentrations of crude organic extract of the red alga P. brasiliense (50%, 100%: natural concentration, and 200% of dry weight: dw) did not affect feeding of this gastropod. In contrast, the three concentrations of crude organic extract of the brown alga D. cervicornis (50%, 100% and 200% dw) inhibited feeding by A. latispina. The chemical deterrent property of D. cervicornis extract against the gastropod A. latispina occurred due to a mixture of the secodolastane diterpenes isolinearol/linearol (4:1--0.08% dry weight). This is the first report showing that Dictyota cervicornis produces a chemical defense against herbivores using secodolastane diterpenoid. In addition, these results widen the action spectrum of secondary metabolites found in seaweed belonging to this brown algal genus.

Animals↗

Effects of cooked molasses blocks and fermentation extract or brown seaweed meal inclusion on intake, digestion, and microbial efficiency in steers fed low-quality hay.

Five ruminally, duodenally, and ileally cannulated steers (376 +/- 8.1 kg of initial BW) were used in a 5 x 5 Latin square to evaluate effects of cooked molasses block supplementation and inclusion of fermentation extract (Aspergillus oryzae) or brown seaweed meal (Ascophyllum nodosum) on intake, site of digestion, and microbial efficiency. Diets consisted of switchgrass hay (6.0% CP; DM basis) offered ad libitum, free access to water, and one of three molasses blocks (0.341 kg of DM/d; one-half at 0600 and one-half at 1800). Treatments were no block (control), block with no additive (40.5% CP; POS), block plus fermentation extract bolused directly into the rumen via gelatin capsules (2.0 g/d; FS), fermentation extract included in the block (2.0 g/d; FB), and seaweed meal included in the block (10 g/d; SB). Steers were adapted to diets for 14 d followed by a 7-d collection period. Overall treatment effect on hay OM intake tended (8.1 vs. 7.6 +/- 0.5 kg/d; P = 0.14) to increase with block supplementation. Total OM intake (8.4 vs. 7.6 +/- 0.5 kg/d; P = 0.01) increased in steers consuming block compared with control. Apparent and true ruminal OM digestibility increased (P = 0.05) with block consumption. Steers fed SB had greater (P = 0.10) true ruminal OM digestibility compared with steers fed POS (61.0 vs. 57.9 +/- 1.6%). True ruminal CP digestibility increased (P = 0.01) with block supplementation compared with control (37.5 vs. 23.6 +/- 3.7%). Addition of fermentation extract did not affect intake or digestion. Treatments did not alter ruminal pH, total VFA, or individual VFA proportions; however, ruminal ammonia increased (P = 0.01) with block supplementation. In situ disappearance rates of hay DM (3.14 +/- 0.44 %/h), NDF (3.18 +/- 0.47 %/h), and ADF (3.02 +/- 0.57 %/h) were not altered by treatment. Seaweed block increased (P = 0.01) slowly degraded CP fraction compared with POS (39.5 vs. 34.0 +/- 2.07%). Similarly, SB increased (P = 0.01) the extent of CP degradability (74.2 vs. 68.9 +/- 1.81%). No treatment effects (P = 0.24) were observed for microbial efficiency. Block supplementation increased intake, and use of brown seaweed meal seemed to have beneficial effects on forage digestibility in low-quality forage diets.

Animal Feed↗

Bioavailability of seaweed iodine in human beings.

The major procedure used to correct iodine deficiency is the universal salt iodization by addition of iodide or iodate to salt with an iodine content varying from 7 to 100 mg/kg of salt depending on the country legislation. As an important fraction of consumers in the world prefers natural products over artificial ones, we investigated the industrial feasibility of naturally iodized salt using seaweed as source of iodine. We report the results of the iodine bioavailability in healthy subjects from two seaweeds: Laminaria hyperborea and Gracilaria verrucosa selected due to their high level in iodine as a mineral or an organic form and low levels of heavy metals. As a control we studied in a normal man the bioavailability of pure mineral iodine such as potassium iodide which was excellent i.e. 96.4% and of pure organic iodine such as monoiodotyrosine which was a little lower i.e. 80.0%. Iodine bioavailability from these two seaweeds was studied in nine normal subjects from Marseille (France) which is an iodine sufficient area based on a median urinary iodine level of 137 microg/day and innine normal subjects from Brussels (Belgium) who present a mild iodine deficiency with a value of 73 microg/day. The iodine bioavailability of Gracilaria verrucosa is better than for Laminaria hyperborea (101% versus 90% in Marseille, t=0.812, NS; 85% versus 61.5% in Brussels, t = 2.486, p = 0.024, S*). The urinary excretion of iodine is lower in Brussels than in Marseille for the same seaweed because part of the iodine is stored in the thyroid (101% versus 85% for Gracilaria verrucosa, t = 1.010, NS; 90% versus 61.5% for Laminaria hyperborea, t = 3.879, p= 0.001, S***).

Biological Availability↗