Diets containing a high percentage of Nori or Konbu algae are well-accepted and efficiently utilised by growing rats but induce different degrees of histological changes in the liver and bowel

Supplemental Microalgal Iron Helps Replete Blood Hemoglobin in Moderately Anemic Mice Fed a Rice-Based Diet

Iron deficiency anemia affects 1.2 billion people globally. Our objectives were to determine if (1) supplemental iron extracted from defatted microalgae (Nannochloropsis oceanica, DGM) and (2) a combination of minute amount of plant phytase and inulin could help replete hemoglobin in anemic mice. Mice (7 weeks old) were fed a control diet (6 mg Fe/kg). After 10 weeks, the mice were assigned to three treatments: control, control + DGM iron (Fe-DGM, 39 mg Fe/kg), or control + 1% inulin + 250 units of phytase/kg (INU−PHY, 6 mg Fe/kg). The mice had free access to diets and water for 6 weeks. The Fe-DGM group had elevated blood hemoglobin (p < 0.01) and a two-fold greater (p < 0.0001) liver non-heme iron over the control. Strikingly, the INU-PHY group had 34% greater non-heme iron than the control, despite the same concentrations of iron in their diets. Fe-DGM group had altered (p < 0.05) mRNA levels of hepcidin, divalent metal transporter 1, transferrin and transferrin receptor 1. Iron extracted from defatted microalgae seemed to be effective in alleviating moderate anemia, and INU-PHY enhanced utilization of intrinsic iron present in the rice diet. Our findings may lead to a novel formulation of these ingredients to develop safer and bioavailable iron supplements for iron-deficient populations.

Effect of microalgae as iron supplements on iron-deficiency anemia in rats

Microalgae are functional iron nutritive fortifiers that can supply more intestinal nanosized iron.

Minerals from Macroalgae Origin: Health Benefits and Risks for Consumers

Seaweeds are well-known for their exceptional capacity to accumulate essential minerals and trace elements needed for human nutrition, although their levels are commonly very variable depending on their morphological features, environmental conditions, and geographic location. Despite this variability, accumulation of Mg, and especially Fe, seems to be prevalent in Chlorophyta, while Rhodophyta and Phaeophyta accumulate higher concentrations of Mn and I, respectively. Both red and brown seaweeds also tend to accumulate higher concentrations of Na, K, and Zn than green seaweeds. Their valuable mineral content grants them great potential for application in the food industry as new ingredients for the development of numerous functional food products. Indeed, many studies have already shown that seaweeds can be used as NaCl replacers in common foods while increasing their content in elements that are oftentimes deficient in European population. In turn, high concentrations of some elements, such as I, need to be carefully addressed when evaluating seaweed consumption, since excessive intake of this element was proven to have negative impacts on health. In this regard, studies point out that although very bioaccessible, I bioavailability seems to be low, contrarily to other elements, such as Na, K, and Fe. Another weakness of seaweed consumption is their capacity to accumulate several toxic metals, which can pose some health risks. Therefore, considering the current great expansion of seaweed consumption by the Western population, specific regulations on this subject should be laid down. This review presents an overview of the mineral content of prevalent edible European macroalgae, highlighting the main factors interfering in their accumulation. Furthermore, the impact of using these marine vegetables as functional ingredients or NaCl replacers in foods will be discussed. Finally, the relationship between macroalgae’s toxic metals content and the lack of European legislation to regulate them will be addressed.

Chemical characterization and antioxidant potential of volatile oil from an edible seaweed Porphyra tenera (Kjellman, 1897)

Background

Porphyra tenera (Kjellman, 1897) is the most common eatable red seaweed in Asia. In the present study, P. tenera volatile oil (PTVO) was extracted from dried P. tenera sheets that were used as food by the microwave hydrodistillation procedure, after which the characterization of its chemical constituents was done by gas chromatography and mass spectroscopy and its antioxidant potential was evaluated by a number of in vitro biochemical assays such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging, nitric oxide (NO) scavenging, superoxide radical scavenging, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging, hydroxyl radical scavenging and reducing power assay and inhibition of lipid peroxidation.

Results

A total of 30 volatile compounds comprising about 99.4% of the total volume were identified, of which trans-beta-ionone (20.9%), hexadecanoic acid (9.2%) and 2,6-nonadienal (8.7%) were present in higher quantities. PTVO exhibited strong free radical scavenging activity by DPPH scavenging (44.62%), NO scavenging (28.45%) and superoxide scavenging (54.27%) at 500 µg/mL. Similarly, it displayed strong ABTS radical scavenging (IC₅₀ value of 177.83 µg/mL), hydroxyl radical scavenging (IC₅₀ value of 109.70 µg/mL), and moderate lipid peroxidation inhibition activity (IC₅₀ value of 231.80 µg/mL) and reducing power (IC_0.5 value of 126.58 µg/mL). PTVO exhibited strong antioxidant potential in a concentration dependent manner and the results were comparable with the BHT and α-tocopherol, taken as the reference standard compounds (positive controls).

Conclusions

Taken together, PTVO with potential bioactive chemical compounds and strong antioxidant activity could be utilized in the cosmetic industries for making antioxidant rich anti-aging and sun-screen lotion and in the food sector industries as food additives and preservatives.

Wakame (Undaria pinnatifida ) modulates hyperphosphatemia in a rat model of chronic renal failure

In chronic renal failure, inorganic phosphate (Pi) retention speeds up the progression to end-stage renal disease. The current therapy for hyperphosphatemia in patients with chronic renal failure consists of dietary Pi restriction combined with administration of Pi binders, but each therapy has practical problems. Thus, the discovery of foods or nutrients that inhibit Pi absorption may be useful for the treatment of hyperphosphatemia. In the present study, we investigated whether wakame (Undaria pinnatifida) is a useful food for the prevention of hyperphosphatemia in a rat model of renal failure. Feeding a diet containing 5% wakame significantly decreased plasma and urinary Pi levels and increased the amount of fecal Pi. In addition, wakame significantly reduced plasma blood urea nitrogen and plasma Pi levels in 5/6 nephrectomized rats fed a high-Pi diet. Biochemical analyses showed that the reduction of intestinal Pi absorption is the main reason for the decrease in plasma Pi levels in rats fed a diet containing wakame. In addition, feeding alginic acid and fucoidan, major components of wakame fiber, was effective in reducing plasma Pi levels in normal rats. Finally, we concluded that wakame may be a useful food for the prevention of hyperphosphatemia in rodents.

Effects of Extraction and Processing Methods on Antioxidant Compound Contents and Radical Scavenging Activities of Laver (Porphyra tenera)

Laver is one of the most consumed edible red algae seaweeds in the genus Porphyra. Laver is primarily prepared in the form of dried, roasted, and seasoned products. We investigated the total polyphenol and flavonoid contents of laver products, and evaluated the in vitro antioxidant properties of solvent extracts from commercially processed laver products. Significant differences in the concentration of phenolic compounds were found among differently processed laver. The total phenolic content for laver extracts ranged from 10.81 mg gallic acid equivalent (GAE)/g extract to 32.14 mg GAE/g extract, depending on extraction solvent and temperature. Laver extracts contained very few flavonoids (0.55 mg catechin equivalent/g extracts to 1.75 mg catechin equivalent/g extracts). 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), hydroxyl radical, and superoxide anion scavenging assays were used to determine the radical scavenging capacities of laver extracts. These assays revealed that the processing method and extraction condition affected the antioxidant potentials of laver. Antioxidant activity of dried laver, roasted laver, and seasoned laver increased in a concentration-dependent manner (100~1,000 μg/mL). The radical scavenging activities of 37°C and 100°C water extracts were lower than that of a 37°C 70% ethanol extract. The highest radical scavenging capacity was observed in the 37°C 70% ethanol extracts of dried laver, roasted laver, and seasoned laver. Overall, these results support that notion that laver contains bioactive compounds, such as polyphenols and flavonoids, which may have a positive effect on health.

Attenuation of histopathological alterations of colon, liver and lung by dietary fibre of barley Rihane in azoxymethane-treated rats

This study was carried out to determine the effect of dietary fibre (DF) of barley Rihane (BR) in the attenuation of colon, liver and lung histopathology alterations induced by azoxymethane (AOM) in rats. Rats were fed a control (C) or experimental diet containing 30% of BR. The intended rats for cancer treatment received two successive subcutaneous injections of azoxymethane (AOM) at 20mg/kg body weight. The colons were analyzed for crypt multiplicity after 12 weeks of treatment. A histological study of the colon, liver and lungs was determined. The results showed that the BR diet significantly reduced the number of aberrant crypt per focus and altered their distribution. In addition, DF of BR increased significantly the mucus secretion compared to control group. The use of the AOM as colon specific carcinogen substance altered the liver and lung architectures, whereas the presence of DF of BR could be a protective factor for these organs.

Effects of seaweed-restructured pork diets enriched or not with cholesterol on rat cholesterolaemia and liver damage

Seaweed enriched-restructured pork (RP) is a potential functional food. However, indications of adverse effects associated with herbal medications, which include among others liver failure, toxic hepatitis, and death have been reported. Cholesterol feeding produces hepatomegalia and fat liver infiltration. The effect of seaweed-RP diet, cholesterol-enriched or not, on plasma cholesterol, liver damage markers, structure, and cytochrome CYP4A-1 were evaluated after 5 wk. Eight rat groups were fed a mix of 85% AIN-93M rodent-diet plus 15% RP. The Cholesterol-control (CC), Cholesterol-Wakame (CW), Cholesterol-Nori (CN) and Cholesterol-Sea Spaghetti (CS) groups respectively consumed similar diets to control (C), Wakame (W), Nori (N), and Sea Spaghetti (S) but as part of hypercholesterolaemic diets. CN and CS significantly blocked the hypercholesterolaemic effect observed in CC group. After 5-wk, N and S diets increased the CYP4A-1 expression. However, seaweed-RPs were unable to reduce the histological liver alterations observed in CC group. Larger and more abundant hepatocellular alterations were found in CS and CN rats suggesting that the hypocholesterolaemic effects of these seaweed-RPs seem to be a two-edged sword as they increased liver damage. Future studies are needed to understand the involved mechanisms.

Evaluation of marine algae Undaria pinnatifida and Porphyra purpurea as a food supplement: composition, nutritional value and effect of intake on intestinal, hepatic and renal enzyme activities in rats

BACKGROUND

There is a long tradition in Eastern countries of consuming seaweeds, although demand for these organisms has also increased in Western countries. However, knowledge of the effects of consumption of algae is limited. In this study the proximate composition and amino acid profile of Undaria pinnatifida (Harvey) Suringar (wakame) and Porphyra purpurea (Olivi) De Toni (nori) were determined. The effects of feeding diets containing 100 g kg(-1) of wakami or nori for 4 weeks on food intake, growth, protein efficiency ratio, diet conversion ratio and some organ weights in growing rats were evaluated. The effects on intestinal, hepatic and renal enzyme activities were also studied.

RESULTS

Both algae are a good source of protein, particularly nori, and contain essential amino acids. There was no effect of alga consumption on trophic balance. Intestinal disaccharidase and hepatic and renal γ-glutamyl transpeptidase activities were lower in alga-fed rats than in the control group, while intestinal leucine aminopeptidase activity was higher in rats fed algae.

CONCLUSION

Both seaweeds are a good source of protein and carbohydrates and contain all essential amino acids. The effects of the two algae on enzyme activities were similar. The inhibition of intestinal disaccharidase activity by seaweed ingestion could be interesting in patients with altered glucose homeostasis.

Effects of Nori- and Wakame-enriched meats with or without supplementary cholesterol on arylesterase activity, lipaemia and lipoproteinaemia in growing Wistar rats

Some seaweeds exert antioxidant and hypocholesterolaemic properties. The effects of diets including restructured meats (RM) containing Wakame (W) or Nori (N) algae on arylesterase (AE) activity and lipoprotein concentration and composition were tested. In the present study, six groups of ten male growing Wistar rats each were fed a mix of 85 % AIN-93M diet and 15 % freeze-dried RM for 35 d. The control group (C) consumed control RM, the W and N groups consumed RM with 5 % W and 5 % N, respectively. The cholesterol-enriched C (CC), W (CW) and N (CN) groups consumed their corresponding basal diets with supplementary cholesterol (2·43 %) and cholic acid (0·49 %). Cholesterol in the diet induced lower (P < 0·001) growth ratios. Both W and N diets significantly increased AE activity. VLDL-cholesterol values were lower in N rats than in W rats. AE activity increased (P < 0·001) in CC and CW rats but not in CN rats compared with their corresponding counterparts. AE was lower (P < 0·05) in the CN group than in the CC and CW groups. The CN diet partially blocked (P < 0·001) the hypercholesterolaemic induction observed in CC and CW diets and reduced TAG levels (at least P < 0·05) with respect to those of CC rats. Although dietary cholesterol supplementation increased total cholesterol, VLDL-cholesterol and (intermediate-density lipoprotein+LDL)-cholesterol (all P < 0·001) in all rats, the CN diet moderately improved the lipoprotein profile of hypercholesterolaemic rats. Changes in AE activity and plasma cholesterol in CN rats but not in CW rats suggest a possible relationship between the two parameters. It is concluded that inclusion of RM enriched with N may be used in hypercholesterolaemic diets to improve lipoprotein metabolism.

A combined Phase I and II open-label study on the immunomodulatory effects of seaweed extract nutrient complex

Background:

Isolated fucoidans from brown marine algae have been shown to have a range of immune-modulating effects. This exploratory study aimed to determine whether a seaweed nutrient complex containing a blend of extracts from three different species of brown algae plus nutrients is safe to administer and has biological potential as an immune modulator. The study was undertaken as an open-label combined Phase I and II study.

Methods:

Participants (n = 10) were randomized to receive the study medication at either a 100 mg (n = 5) or 1000 mg (n = 5) dose over 4 weeks. The primary outcome measurement was in vivo changes in lymphocyte subsets. The secondary outcome measures were ex vivo changes in T-lymphocyte (CD4 and CD8) activation, phagocytosis of granulocytes and monocytes, T helper 1/T helper 2 cytokines, and serum oxygen radical absorbance capacity.

Results:

The preparation was found to be safe over the 4 weeks at both doses tested. There were no clinically relevant changes to blood measurements of hemopoietic, hepatic, or renal function. Immunomodulatory measurements showed no dose response between the two doses. The combined results from the two doses demonstrated a significant increase in cytotoxic T cell numbers and phagocytic capacity in monocytes, and a significant decrease in levels of the inflammatory cytokine interleukin 6. A separate analysis of the 100 mg dose (n = 5) alone showed a significant linear component over time (P < 0.05) for phagocytosis by both granulocytes and monocytes.

Conclusion:

The seaweed nutrient complex was safe to use when taken orally over 4 weeks. The preparation was demonstrated to have potential as an immune modulator, and this bioactivity deserves further exploration.

Evaluation of the marine alga Ulva rigida as a food supplement: effect of intake on intestinal, hepatic, and renal enzyme activities in rats

The use of seaweeds as a food is more widespread in Eastern than in Western countries, although demand for these plants has increased in the West because their possible usefulness as dietary supplements. However, very little is known about the effects of regular consumption of algae. The aim of the present study was to determine the composition of Ulva rigida and to evaluate the effects of dietary supplementation of the diet with 10% alga for 4 weeks on dietary intake, growth, protein efficiency ratio, diet conversion ratio, and some organ weights in growing male rats. We also studied the effect of inclusion of the alga in the diet on intestinal, hepatic, and renal enzymatic activities. U. rigida was found to be a good source of protein and carbohydrates. Food intake was higher in the U. rigida group than in the control group, but ingestion of alga did not have any effect on the other trophic parameters. The intestinal disaccharidase and leucine aminopeptidase activities were lower in rats fed with alga than in control rats, but γ-glutamyl transpeptidase activity was higher in the kidneys of alga-fed rats than in control rats. U. rigida contains high amounts of protein, carbohydrates, vitamins, and minerals and low amounts of lipids. Analysis of the amino acid composition revealed good-quality protein. The addition of alga to the diet inhibited disaccharidase activities, which suggested that alga consumption could be useful in some chronic disorders associated with pertubations of glucose homeostasis caused by carbohydrate absorption.

Composition, nutritional aspects and effect on serum parameters of marine algae Ulva rigida

BACKGROUND

Algae are commonly consumed in Asia and have also gained popularity in Europe. However, data on the bioavailability of their components are limited. The present study was designed to determine the composition of Ulva rigida and the effects of inclusion of 10% of the algae in a standard diet for 4 weeks on nutritive value and serum parameters in order to consider the usefulness of Ulva as a dietary supplement.

RESULTS

Ulva rigida is rich in protein, carbohydrates, fibre, vitamins and minerals and has a low lipid content. Analysis of the amino acid composition revealed good-quality protein. The algae were well accepted by experimental animals and did not significantly change nutritional parameters but reduced LDL cholesterol.

CONCLUSIONS

Ulva rigida is an excellent source of nutrients and could improve a balanced diet. Further studies are required to research the potential of the seaweed as a natural source of bioactive compounds.

Effect of seaweed and cholesterol-enriched diets on postprandial lipoproteinaemia in rats

High postprandial lipaemia increases cardiovascular risk. Algae consumption may affect postprandial lipoproteinaemia. The effects of dietary alga and cholesterol supplementation on postprandial lipaemia and lipoproteinaemia and arylesterase (AE) activity in growing male Wistar rats were tested in the present study. Six groups of ten rats were fed a casein-based diet for 3 weeks. Three of the diets contained 2.4 % cholesterol-raising agent (Chol), while the other three did not (NChol). Seven percentage of the control diets (NChol-C and Chol-C) consisted of a cellulose-wheat starch mix (35:65), while the Nori alga diets (NChol-N and Chol-N) and Konbu diets (NChol-K and Chol-K) contained 7 % of each respective freeze-dried alga. Postprandial plasma was obtained after a 3 h diet withdrawal. Supplementary cholesterol and alga type significantly affected (at least P < 0.05) the cholesterol, TAG, phospholipid and protein contents of the various lipoprotein fractions. AE enzyme activity increased (P < 0.05) in NChol rats given Nori and Konbu diets. NChol-K, but not NChol-N, rats displayed higher (P < 0.05) plasma cholesterol, TAG and phospholipid levels than NChol-C animals. NChol-K rats presented higher TAG, phospholipid, protein and lipoprotein mass values than their NChol-C counterparts. Inclusion of algae in Chol diets decreased (P < 0.001) the postprandial hypertriacylglycerolaemia. The Chol-N diet affected most lipoprotein fraction contents. Chol-N rats had lower postprandial cholesterolaemia and a better lipoprotein profile (fewer LDL and a tendency toward more HDL and fewer cholesterol-enriched VLDL) than Chol-K rats, suggesting that Nori is the alga of choice in dietary treatment of hypercholesterolaemia.

Characteristics and nutritional and cardiovascular-health properties of seaweeds

While marine algae have traditionally formed part of the Oriental diet, their major use in Western countries has been in the phytocolloid industry. Only a few coastal communities outside Asia have customarily used seaweeds as components of special dishes. Of late, however, seaweeds have gained importance as foodstuffs in Western countries and most recently as components of functional foods because of their high dietary fiber, mineral, vitamin, and phytochemical content, low energy levels, and high concentrations of certain polyunsaturated fatty acids. The present paper reviews the available data for some of the components of the major edible algae and studies several factors that can affect their physiochemical properties (e.g., hydration, water and oil-holding capacity, fermentability, binding capacity, etc.) and, in turn, their nutritional importance. The effects of marine alga consumption on growth and body weight, mineral availability, lipid metabolism, blood pressure, and antioxidant properties are reviewed, together with preliminary data on the effects of some functional foods containing seaweeds on lipid metabolism and gene expression of enzymes engaged in antioxidant protection. This review concludes with some remarks regarding the danger of the improper use of seaweeds in herbal medications. In addition, as the properties of algae are highly dependent on their individual composition, any generalization regarding these properties may be considered misleading and scientifically inappropriate.

Diet and healthy ageing 2100: will we globalise local knowledge systems?

Diet and health clearly are linked intrinsically. Today, more than ever food is functionalized and tailor made for specific groups (e.g. athletes, the elderly, and people with specific conditions). Increased life expectancy has resulted in an increase in the quest for diets which allow for a healthy ageing. In looking back 100 years, we try to assess how of our diets will evolve in the next 100 years and how this may be linked to a 'healthier ageing'. Our argument centres around a series of dichotomies which we used to explain the main changes in dietary habits and how this impacts on health--the continuous move from dietary traditions which are local, low in technological input and based on empiricism, to diets which are global, require high technological input and are science-based. The innovations our societies have achieved over the last century have allowed us to improve our diet based on a better scientific understanding of the health benefits of such diets, but this is often not achieved due to commercial considerations. This will require that all sectors of the food industry work towards healthy and economically affordable diets. In addition, there will be a continuous demand by the consumers to ascertain that 'our' foods are not only healthy but also convenient and easy to prepare. Healthy ageing will require us to look at a multitude of aspects of foods, to integrate this knowledge and to apply it in all sectors of food production.

A Nori but not a Konbu, dietary supplement decreases the cholesterolaemia, liver fat infiltration and mineral bioavailability in hypercholesterolaemic growing Wistar rats

The nutritional consequences of algae consumption in young populations consuming hypercholesterolaemic diets have hardly been investigated. This study tests the effect of algae supplementation of cholesterol-enriched balanced diets on growth, dietary efficiency ratio, mineral intake and absorption, organ weight and structure and cholesterolaemia in growing Wistar rats. Three groups of ten rats each were fed for 3 weeks with experimental diets containing 93 % casein-soyabean oil base with 2.4 % cholesterol-raising agent and 7 % supplement. The control group received cellulose (35 %), group 2 consumed Nori (33.8 % fibre) and group 3 consumed Konbu (36.1 % fibre). Food intake and body weight gain were not significantly affected. Algae groups presented significantly higher dietary efficiency ratio values than control rats. Apparent absorption of several minerals appeared significantly affected, mainly in Nori-fed rats, with a significant decrease in the ratio of Zn and Cu intakes and apparent absorption. Nori diet significantly decreased plasma cholesterol. Algae supplement did not significantly affect organ size and structure. Control and Konbu rats showed severe liver fat infiltration, while Nori rats exhibited a significantly lower degree of lipid-like hepatocyte vacuolization but light to moderate leukocyte infiltration. Light to moderate scaling off of the epithelium and moderate submucosa oedema was observed in all groups. Although long-term studies are needed to check the possible extrapolation of these data to human subjects, it can be concluded that a Nori, but not a Konbu, dietary supplement reverses the negative effect of dietary cholesterol intake and also appears to be related to mineral availability in growing subjects.

Differential effects of konbu and nori seaweed dietary supplementation on liver glutathione status in normo- and hypercholesterolaemic growing rats

The effects of six balanced diets for 3 weeks on dietary intake, growth, liver weight and fat, plasma cholesterol, total antioxidant capacity, liver glutathione status and antioxidant enzymes in growing male Wistar rats were studied. Ten rats per group were fed casein- and soyabean-based diets with or without 2.4 % cholesterol-raising agent. Seven percent of the diet consisted of a cellulose-wheat starch mix (35:65; control diets), freeze-dried nori (nori diets) or konbu (konbu diets). The 7 % dietary supplement of seaweeds was well accepted and induced normal growth rates in rats. Except for food intake, total and reduced glutathione and total antioxidant capacity, dietary cholesterol addition significantly affected (at least P<0.05) all parameters studied. Alga consumption affected total and reduced glutathione, glutathione reductase activity, plasma cholesterol, and total and cholesterol-adjusted total antioxidant capacity (at least P<0.05). A significant cholesterol-alga interaction was found for liver weight, total glutathione peroxidase (GSH-Px) and the Se-dependent GSH-Px:total GSH-Px ratio (at least P<0.05). GSH-Px activity increased in cholesterol-fed nori rats mainly as Se-dependent GSH-Px, while in konbu and control groups the GSH-Px activity was related to increases in both non-Se-dependent and Se-dependent GSH-Px activities. The decrease in the antioxidant status of konbu rats was related to the high As content of this alga, which led to a compensatory increase in glutathione reductase activity in these animals. In conclusion, although some antioxidant compounds are present in algae, other dietary compounds, such as As, induced poor antioxidant status in rats.