Dephytinization of wheat and rice brans by hydrothermal autoclaving process and the evaluation of consequences for dietary fiber content,antioxidant activity and phenolics

Autoclaving process applied to wheat and rice bran samples to decrease the phytic acid content and to enhance the functional and nutritional properties (dietary fiber and phenolic content, antioxidant activity) of bran samples. All hydrothermal treatments caused significant decreases in phytic acid contents of both wheat (95.2%) and rice bran (95.6%) samples. The most effective process conditions on enhancing the total dietary fiber content for both bran samples were pH 4.0 level and 1.5 h holding time. Autoclaving treatment resulted in a decrease in total phenolic contents after holding for 90 min and at 121 °C at their native pH levels. Autoclaving for 90 min caused the greatest degree of increment in the total antioxidant activity of wheat (12%, pH 4.0) and rice bran samples (2%, pH 3.5). Autoclaving treatment was found as quite effective method for both dephytinization and enrichment of wheat and rice brans as a functional food ingredient.Industrial relevanceAuthors believe that the study presents important new information in terms of both enhancing functional properties of wheat and rice brans by hydrothermally dephytinization treatment and revealing the correlation between hydrothermal treatment and functional ingredients of brans. In this way, proposed method transforms inexpensive and easily accessible sources into important food ingredients and gives them added value. Hydrothermal treatment also enables food industry to use cereal brans as functional ingredients in the applications of both designing and enriching new and healthy food formulations.     

In-vitro mineral binding capacity of five fiber sources and their insoluble components for magnesium and calcium1

In-vitro binding of calcium (Ca) and magnesium (Mg) by total dietary fiber, hemicellulose A (HCL A), lignocellulose (LCL), cellulose (CL), and lignin (L) fractions isolated from rice bran (RB), wheat bran (WB), oat fiber (OF), apple fiber (AF) and tomato fiber (TF) was evaluated. At pH 6.8, significant amounts of Ca were bound by whole fibers, ranging from 800 μg g⁻¹ for RB to 10 097 μg g⁻¹ for TF. Mg bound by whole fibers varied from 496 μg g⁻¹ for OF to 2177 μg g⁻¹ for WB. Re-acid washing (pH<2.0) released 95–99% of the Ca and Mg bound to the fibers. Fibers with the highest endogenous Ca and Mg concentrations bound significantly (P<0.05) the highest amounts of the minerals studied. The Ca bound by HCL A varied from 9753 μg g⁻¹ for RB to 11 337 mg g⁻¹ for TF, whereas Mg bound varied from 1151 μg g⁻¹ for OF to 5626  μg g⁻¹ for TF hemicellulose fractions, respectively. Among the fiber components, Mg binding decreased in the order HCL A>LCL>L>CL, whereas Ca bound was in the order HCL A>LCL>CL>L. A relatively strong correlation was observed between the combined effects of protein content, hemicellulose, and lignin vs total Ca and Mg bound. 1998 Elsevier Science Ltd. All rights reserved     

Investigation of the interaction between soluble antioxidants in green tea and insoluble dietary fiber bound antioxidants

This work investigates the possibility of interaction between insoluble dietary fiber bound antioxidants, specifically of wheat bran, and soluble antioxidants like those provide by aqueous infusions of green tea. Solutions of pure catechins were also assayed for comparison with those naturally found in tea. To accomplish this, the aqueous and alcohol soluble fractions as well as the lipid components of wheat bran were firstly removed and the freeze-dried insoluble residue was then treated with different concentrations of green tea infusions or aqueous solutions of epicatechin (EC) and epigallocatechin-3-gallate (EGCG) for certain time. Treatment with EC (0–200 μM) had no significant effect on the antioxidant capacity of insoluble bran fraction. However, treatment with EGCG significantly (p < 0.05) increased linearly the antioxidant capacity as a function of concentration (0–100 μM). Treatment with great tea infusions (1–3 g/100 ml) also increased the resulting antioxidant capacity of insoluble bran fraction, but the effect was lesser at higher infusion concentrations. Liquid chromatography couple to mass spectrometry (LC–MS) analyses of aqueous phases after treatment indicated comparable levels of decrease in the concentrations of catechins confirming their reaction with the radical forms of antioxidants bound to insoluble bran matrix.     

Mechanism of the interaction between insoluble wheat bran and polyphenols leading to increased antioxidant capacity

This study aimed to provide an in-depth investigation of the interaction between insoluble wheat bran and polyphenols. Treatment with tannic acid, but not gallic acid, increased the bound antioxidant capacity of insoluble wheat bran depending on its aqueous concentration (p < 0.05). Among the beverages tested (white and red wines, black and green tea infusions), treatment with green tea infusion caused the highest increase in the total antioxidant capacity. Temperature, time, air and pH were found to significantly affect the reaction between insoluble wheat bran and polyphenols. The bound antioxidant capacity of insoluble bran increased to above 100 mmol TE.kg^− 1 after treatment with green tea infusion at optimum conditions (50 °C, pH 9.0, no airflow). Concentration of free amino groups available in wheat bran significantly decreased (59.5%) after the treatment. The results suggested that polyphenols are oxidized to quinones under alkaline conditions further bound to free amino groups available on the surface of wheat bran.     

Effect of ultrafine grinding on hydration and antioxidant properties of wheat bran dietary fiber

Wheat bran dietary fiber (DF) powders was prepared by ultrafine grinding, whose effects were investigated on the composition, hydration and antioxidant properties of the wheat bran DF products. The results showed that ultrafine grinding could effectively pulverize the fiber particles to submicron scale. As particle size decrease, the hydration properties (water holding capacity, water retention capacity and swelling capacity) of wheat bran DF were significantly (p < 0.05) decreased and a redistribution of fiber components from insoluble to soluble fractions was observed. The antioxidant activities of wheat bran and DF before and after grinding were in terms of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, ferrous ion-chelating activity, reducing power and total phenolic content (TPC). Compared with DF before and after grinding, micronized insoluble DF showed increased chelating activity, reducing power and TPC yet decreased DPPH˙ radical scavenging activity. Positive correlations were detected between chelating activity, reducing power and TPC.     

Free radical-scavenging capacity and inhibitory activity on rat erythrocyte hemolysis of feruloyl oligosaccharides from wheat bran insoluble dietary fiber

Water-soluble feruloyl oligosaccharides, which were released from wheat bran insoluble dietary fiber treated with xylanase from Bacillus subtilis and further purified with Amberlite XAD-2, were evaluated for their 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity and their capacity in inhibition of rat erythrocyte hemolysis mediated by 2,2′-azobis-2-amidinopropane dihydrochloride (AAPH) under in vitro conditions. The EC₅₀ value of the water-soluble feruloyl oligosaccharides against the DPPH radical was 0.52 mg/ml. The oxidative hemolysis of rat erythrocytes induced by AAPH was suppressed by the water-soluble feruloyl oligosaccharides in a concentration- and time-dependent manner. The water-soluble feruloyl oligosaccharides, at a concentration of 4 mg/ml, showed 91.7% of inhibition of rat erythrocytes hemolysis, and the erythrocyte hemolysis could be retarded for more than 120 min. These data indicated that the water-soluble feruloyl oligosaccharides from wheat bran insoluble dietary fiber might have potential as natural antioxidants.     

Diet-induced changes in alginate- and laminaran-fermenting bacterial levels in the caecal contents of rats

Brown algae contain soluble polysaccharides, such as alginic acid, fucoidan and laminaran. To assess the induction of dietary fiber-fermenting bacteria in the intestine, rats were fed diet containing no dietary fiber (control) or 2% w/w of the polysaccharides for 2 weeks. The levels of dietary fiber-fermenting bacteria in caecal contents were determined using decimal dilution culture containing 1% w/v of the fibers. Caecal microbiota in the rats was analyzed using polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). In the culture method, 4–9 log viable cells/g caecal content of alginate-fermenting bacteria was detected in rats fed alginate, while this was not detected in rats fed the control diet. Although laminaran-fermenting bacteria were detected in control rats (4–9 log viable cells/g), the level observed in rats fed laminaran was 8 or 9 log viable cells/g. On the other hand, fucoidan-fermenting bacteria were not detected in rats fed fucoidan. DGGE analysis showed laminaran administration increased the diversity of bacterial bands. Clostridium spp. and Parabacteroides distasonis were detected as typical species in rats fed alginate and laminaran. The results indicate that the intake of soluble fermentable fibers in edible brown algae can alter the intestinal microbiota and its fermentation capacity.     

Antioxidant properties and components of some commercially available varieties of rice bran in Pakistan

The antioxidant activity of five indigenous rice bran varieties, i.e. Rice bran-Super kernel (RB-kr), Rice bran-Super 2000 (RB-s2), Rice bran-Super Basmati (RB-bm), Rice bran-Super-386 (RB-86) and Rice bran-Super fine (RB-sf), collected from the same agricultural plots, was evaluated. The order of antioxidant activity was evaluated by measurement of total phenolic content, antioxidant activity in linoleic acid system, reducing power, metal chelating ability, scavenging capacity by DPPH radical and ABTS cation radical and conjugated dienes. Determination of major antioxidant components reported in rice bran, i.e. tocopherols, tocotrienols and γ-oryzanol, was made using reverse phase HPLC. However, for comparison of tocopherol content, quantification was also done by voltammetry. The overall order of antioxidant activity was RB-kr > RB-s2 > RB-bm > RB-86 > RB-sf. However, according to the chelating activity and conjugated dienes assays the antioxidant efficacy of RB-sf was higher than RB-bm and RB-86. Antioxidant power was correlated with growth period and irrigation water demand by a particular variety. A strong correlation of these two parameters with antioxidant activity was observed. RB-kr has the longest growth period and takes the least amount of water out of the series and exhibits highest antioxidant activity. Strongly reverse behavior was observed in case of RB-sf.     

The potential of cholecalciferol and 25-hydroxyvitamin D3 enriched diets in laying hens,to improve egg vitamin D content and antioxidant availability

Sixty Hy-line brown hens were randomly assigned to four barns (n = 4) to investigate the effects of cholecalciferol (vitamin D₃) versus 25-hydroxyvitamin D₃ (25-OH-D₃) enriched diets on egg vitamin D concentration, antioxidant activity and egg quality parameters. Experimental design was a 4 × 4 Latin square consisting of 4 experimental treatments and 4 experimental periods. The treatments were (1) 1500 IU of vitamin D₃ (2) 3000 IU of vitamin D₃ (3) 1500 IU of vitamin D₃ and 37.5 μg of 25-OH-D₃ (4) 75 μg of 25-OH-D₃ per kg of feed. Hens offered 75 μg of 25-OH-D₃ had a higher (P < 0.05) total vitamin D egg yolk content (5.06 μg/egg), and antioxidant activity compared to other dietary treatments. The results demonstrates that the enrichment of hen diets with 25-OH-D₃ may be a useful approach and may contribute between 25 and 33% towards total vitamin D daily requirements while also improving antioxidant status of eggs.Industrial relevanceVitamin D deficiency is now regarded as a major issue in northern Europe and has been described as a pandemic. A growing interest in vitamin D food fortification in northern Europe to satisfy the current dietary intake recommendations has been observed. The use of a bio-addition approach for increasing vitamin D intake through biofortification of livestock feeds attracts attention. Enrichment of the hen's diet with vitamin D may also supply additional benefits of increasing antioxidant activity. This increase in antioxidant activity may have the ability to increase food quality and extend the shelf life. This study explores the effect of vitamin D enriched diets fed to laying hens on vitamin D egg yolk content and antioxidant activity in the egg. These enriched diets could demonstrate that enrichment of hen diets with 25-hyroxvitamin D₃ may be a useful approach for tackling low vitamin D intakes and improving antioxidant capacity of eggs.     

Intracellular ROS scavenging and antioxidant enzyme regulating capacities of corn gluten meal-derived antioxidant peptides in HepG2 cells

The objective of this study was to investigate the intracellular reactive oxygen species (ROS) scavenging activities and antioxidant enzyme regulating capacities of corn gluten peptide fractions (CPFs) in HepG2 cells. A cellular antioxidant activity (CAA) assay was used to assess their antioxidant activities and revealed that both CPF1 (molecular weight < 1 kDa) and CPF2 (molecular weight between 1 and 3 kDa) exhibited high cellular antioxidant activities with EC₅₀ values of 2.85 ± 0.19 mg/mL and 5.05 ± 0.32 mg/mL, respectively. Both CPFs also exhibited cytoprotective effects and intracellular ROS scavenging activities in HepG2 cells subjected to oxidative stress by oxidation with H₂O₂. In addition, at concentrations of 2.50 mg/mL, the CPFs increased the activity levels of superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR), as well as the total glutathione (GSH) levels in oxidized HepG2 cells (from 86.54% to 114.14% (CPF1) or 109.72% (CPF2) for SOD activity; from 71.91% to 107.64% (CPF1) or 106.50% (CPF2) for CAT activity; from 70.52% to 103.01% (CPF1) or 104.10% (CPF2) for GR activity; and from 81.39% to 114.00% (CPF1) or 108.82% (CPF2) for total GSH levels). These results suggested that both CPF1 and CPF2 exhibited positive effects on the activities of the intracellular antioxidant enzymes SOD, CAT and GR, as well as on the total GSH levels in HepG2 cells under conditions of oxidative stress. Furthermore, size exclusion gel chromatography and MALDI-TOF/TOF mass spectrometry revealed that the molecular weights of the antioxidant peptides in CPF1 were between 500 Da to 900 Da, and a novel antioxidant peptide consisting of GLLLPH (Gly-Leu-Leu-Leu-Pro-His) was identified in CPF1.     

Triticale bran and straw: Potential new sources of phenolic acids,proanthocyanidins, and lignans

The distribution of phenolic acids (free and bound), proanthocyanidins, and lignans in defatted triticale bran and straw was determined. For comparison, wheat, rye and oat brans as well as triticale flakes and leaves were also assayed. Most phenolic acids were present in the bound form (89–98%), and released under alkaline extraction conditions. The content of phenolic acids ranged from 65.2 to 252.5 mg/100 g in samples in which ferulic acid predominanted. Triticale straw was the richest source of proanthocyanidins, containing 862.5 mg/100 g (catechin equivalents) of tissue. Triticale straw contained 0.27 mg/100 g of lignan secoisolariciresinol diglucoside (SDG), whereas the bran had only 0.01 mg/100 g. The oxygen radical absorbance capacity (ORAC, μM Trolox equivalents/g defatted material) showed that antioxidant activity of bound phenolics was higher than those of free phenolics. This is the first report on phenolic acids, proanthocyanidin, and lignans content of Canadian triticale by-products, indicating that they may have the potential for use as nutraceuticals and/or functional food ingredients.     

The effects of strawberry,black currant,and chokeberry extracts in a grain dietary fiber matrix on intestinal fermentation in rats

The objective of this work was to study the composition, hydration properties and oil holding capacity, antioxidant properties and the physiological effects on the digestive system of dietary preparations containing wheat or oat fiber enriched with polyphenol extracts from strawberry, chokeberry, and black currant pomace. By the addition of black currant, strawberry and chokeberry polyphenol extracts to grain fibers preparations with corresponding polyphenol content of 0.7%–0.8%, 1.1%–1.2%, and 2.5%–2.9% were obtained. The preparations were used as part (8%) of a modified AIN-93 diet given to growing Wistar rats (8 animals per group) over a period of 4 weeks. The highest antioxidant potential had grain–chokeberry preparations with the greatest polyphenol content, while grain–black currant preparations exhibited the lowest antioxidant potential with the smallest polyphenol content. The addition of strawberry and chokeberry extracts caused a decrease in the activity of bacterial β-glucosidase and α-galactosidase, while black currant extract led to increased activity of β-galactosidase and β-glucuronidase. The production of short chain fatty acids (SCFAs) in the caecum of rats fed the grain–strawberry preparation, rich in ellagitannins, was considerably higher than the grain–black currant preparation, rich in proanthocyanidins and anthocyans, or the grain–chokeberry preparation with the highest polyphenol content (78.3 vs. 64.7 vs. 56.3 μmol/100 g body weight, p = 0.012). In comparison to preparations without polyphenols only chokeberry extract significantly decreased SCFA concentration. The grain–strawberry preparations were characterized by a higher antioxidant potential per unit of polyphenol content and exhibited a more beneficial influence on the fermentation processes in the caecum of rats than the grain–black currant and grain–chokeberry preparations.     

Anti-obesity effects of epigallocatechin-3-gallate,orange peel extract,black tea extract,caffeine and their combinations in a mouse model

The anti-obesity effects of epigallocatechin-3-gallate (EGCG), orange peel extract (OPE), black tea extract (BTE), and caffeine (CF) in female CF-1 mice were studied. Female CF-1 mice were fed high-fat diets containing 0.1% EGCG, 0.2% OPE, 0.2% BTE and 0.05% caffeine alone and in combination for 10 weeks. The body weight gain and weights of abdominal fat and brown adipose tissue were significantly reduced in mice whose diets contained OPE, BTE, caffeine, OPE + BTE and OPE + CF. Notably, mice fed a high-fat diet supplemented daily with 0.2% OPE + 0.2% BTE + 0.05% CF prevented body weight gain by 48.8%, parametrial fat pad weight by 88.2%, retroperitoneal fat pad weight by 82.8% and brown adipose tissue by 63.7% compared with mice fed a high-fat diet. On the basis of these findings, it was concluded that oral feeding of orange peel extract, black tea extract and caffeine had anti-obesity effects by suppressing body weight gain and adipose tissue formation.     

Dietary fatty acid determines the intestinal absorption of lutein in lutein deficient mice

The present investigation was undertaken to study the influence of dietary lipids [olive (OO), coconut (CNO), groundnut (GNO), soybean (SBO), sunflower (SFO), rice bran (RBO), corn (CO), palm (PO), fish (FO) oils] on the bioavailability and antioxidant property of lutein in lutein deficient (LD) mice. Lutein (200 μM) was dispersed in dietary lipids and administered to LD mice for a period of 15 days. The plasma lutein levels were found to be highest in OO (82%) and CNO (68%), when compared to the control (mixed micelle) group. Further, positive correlation was found between intestinal triacylglycerol lipase and plasma lutein levels, confirming the crucial role of intestinal lipase on lutein micellarization and its intestinal uptake. Results revealed an affirmative correlation between triglycerides, low density lipoproteins and high density lipoprotein levels with plasma and tissue lutein levels, signifying their role in the transportation of newly absorbed lutein to target tissues. Furthermore, lutein accumulation in the liver and the eye was highest in the OO (120% and 117%) and CNO (105% and 109%) fed groups, compared to control. Lutein deficiency resulted in elevated (p < 0.05) levels of lipid peroxides, superoxide dismutase, and catalase in plasma and liver microsomes, which have been decreased significantly on feeding lutein. These results may be due to the influence of oleic (dominant in OO) and lauric (dominant in CNO) acids on the activity of intestinal lipase, portal absorption, triglycerides, lipoprotein or cholesterol flux between liver and peripheral tissues, which may modulate the uptake and transport of lutein.     

Antioxidant and type II diabetes related enzyme inhibition properties of methanolic extract of an underutilized food legume,Canavalia ensiformis (L.) DC: Effect of traditional processing methods

The methanolic extract of Canavalia ensiformis (L.) DC (Jack bean) seed, an underutilized food legume collected from India was analyzed for antioxidant and health relevant functional properties. The raw seeds contained total free phenolic content of 12.98 ± 1.63 g catechin equivalent/100 g extract DM. The raw seed extract exhibited ferric reducing/antioxidant power (FRAP, 1218 mmol Fe[II]/mg extract), inhibition of β-carotene degradation (49.81%), radical scavenging activity against DPPH (56.78%) and superoxide (35.89%). In addition, 77.56% of α-amylase and 75.45% of α-glucosidase enzyme inhibition characteristics were found under in vitro starch digestion bioassay. Sprouting + oil-frying caused an apparent increase on the total free phenolic content with significant improvement on antioxidant and free-radical scavenging capacity, while soaking + cooking as well as open-pan roasting treatments showed diminishing effects. Inhibition of α-amylase and α-glucosidase enzyme activities were declined to 22.69 and 42.69%, respectively during sprouting + oil-frying treatment is more desirable for the dietary management of type II diabetic patients.     

Effect of dietary grape seed extract and Cistus ladanifer L. in combination with vegetable oil supplementation on lamb meat quality

Thirty-six Merino Branco lambs were assigned to six dietary treatments: control diet (C) consisting of 90% dehydrated lucerne and 10% wheat bran; C with 6% of oil blend (CO); C with 2.5% of grape seed extract (GS); GS with 6% of oil blend (GSO); C with 25% of Cistus ladanifer (CL), and CL with 6% of oil blend (CLO). Meat lipid and colour stability was then evaluated during 7 days of storage. The effect of inclusion of grape seed extract and C. ladanifer in diets on meat sensory properties was also evaluated. Meat antioxidant potential, determined after oxidation induction by a ferrous/hydrogen peroxide system, decreased with oil supplementation (P < 0.001), but inclusion of grape seed extract and C. ladanifer in diets protected the meat against lipid oxidation (P = 0.036). Meat colour was not affected by diets. Inclusion of grape seed extract and C. ladanifer in diets did not change the sensory properties of meat.     

β-Conglycinin (7S) and glycinin (11S) exert a hypocholesterolemic effect comparable to that of fenofibrate in rats fed a high-cholesterol diet

The hypocholesterolemic effect of isolated soybean proteins and fenofibrate in rats was compared. Forty-five rats were divided into five groups: standard (STD; casein), high cholesterol (HC; STD plus 1% cholesterol/0.5% cholic acid), HC + β-conglycinin, HC + glycinin and HC + fenofibrate. The proteins and the drug were administered by gavage for 28 days. The proteins decreased total cholesterol (TC) and triacylglycerol (TG) in the plasma of the rats fed HC diet, to values very close to those fed on fenofibrate. High density lipoprotein cholesterol (HDL-C) levels in the plasma were increased by the β-conglycinin, glycinin and fenofibrate groups. The largest TC reduction in the liver was observed in the fenofibrate group; in contrast, the β-conglycinin and glycinin groups exhibited reduced the levels of hepatic TG and TC. Based on these data, it could be suggested that the oral daily administration of isolated soybean proteins, in the range of 2.75% of the protein ingested daily, can promote a reduction in TC and TG in the plasma of rats fed hypercholesterolemic diets.     

Hypocholesterolemic effect of dietary evening primrose (Oenothera paradoxa) cake extract in rats

The objective of this study was to determine the effects of dietary evening primrose cake extract (E) on the lipid indices and lipid peroxidation products in growing rats fed cholesterol-free standard diet (S) or diets enriched with 1% cholesterol (C). All animals were divided into five groups of 10 and were fed during 4 weeks experimental diets: group (Gr) 1–standard diet (S); Gr 2–S diet supplemented with 1% E (S+1%E); Gr 3–with 1% C (S+1%C); Gr 4–S+1%C+0.5%E and Gr 5–S+1%C+1%E. Dietary E significantly decreased plasma total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) but did not change the high density lipoprotein cholesterol (HDL-C) either in rats fed cholesterol-free or enriched-in-cholesterol diets. Plasma TC were 98.7, 81.3, 144.6, 114.5 and 99.1 mg 100 ml⁻¹, whereas LDL-C values were 19.4, 7.6, 77.2, 43.6 and 27.6 mg 100 ml⁻¹ in Groups 1–5, respectively. Supplementation of diet with E significantly elevated triglyceride and phospholipid concentrations in the liver; also 1% E with C (S+1%C+1%E) caused significant TC accumulation in the liver and elevated malondialdehyde concentrations in plasma and erythrocytes. In conclusion, this study demonstrates, for the first time, that evening primrose cake extract (E) possesses strong hypocholesterolemic action. Its antioxidative properties, especially in animals loaded with dietary cholesterol, are less clear and need further studies..     

Consumption of baru seeds [Dipteryx alata Vog.], a Brazilian savanna nut,prevents iron-induced oxidative stress in rats

The protective effect of plant-based foods in human health has been attributed to the presence of bioactive compounds in all parts of the plants. A previous study found a high level of minerals, tannins and phytic acid in the baru nut (Dipteryx alata Vog.), which is a native fruit of the Brazilian savanna. This study investigated the antioxidant activity (AA) of the aqueous and ethyl acetate extracts of the baru nut and the effect of the consumption of this nut on the oxidative status of rats supplemented orally with iron. The AA was evaluated in vitro using the ferric reducing antioxidant power (FRAP), β-carotene/linoleic acid system and free-radical scavenging (DPPH) assays. The total polyphenol concentration was determined spectrophotometrically using the Folin–Ciocalteu reagent. The in vivo study was conducted in male Wistar rats that were fed an AIN-93M diet with or without 10% baru nut or 1% phytic acid and supplemented daily with iron or saline by gavages for 17 days. The liver, heart and spleen were collected for the determination of the malondialdehyde (MDA), carbonyl protein and iron concentrations. The specific activities of catalase, glutathione reductase, glutathione peroxidase and glutathione S-transferase were also determined in these tissues. A T test was used to compare the results among the rats groups and between the different baru nut extracts (p < 0.05). The aqueous extract of the baru nut contained a higher level of phenolic compounds and a higher antioxidant activity, as measured by FRAP and the β-carotene/linoleic system, relative to the EtOAc extract. The iron supplementation reduced the body weight gain, increased the levels of iron and MDA in the liver and the spleen and increased the carbonyl levels in all three tissues. Consumption of the baru nut reduced the carbonyl levels in the liver, heart and spleen of the iron-supplemented rats (p = 0.002, 0.012 and 0.036, respectively) relative to the heart carbonyl level of rats that were fed the control diet (p = 0.000); it also marginally reduced the iron-induced lipid oxidation in the liver (p = 0.117) and the spleen (p = 0.074). Phytic acid reduced the carbonyl level in the spleen (p = 0.020) and marginally reduced the carbonyl level in the liver (p = 0.098) of iron-supplemented rats. These results demonstrated that the consumption of the baru nut protects tissues against iron-induced oxidative stress, and the phytic acid from the baru nut may be partially responsible for this protective effect; however, other compounds such as phenols may also be involved.