The intake of dietary indigestible fraction in the Spanish diet shows the limitations of dietary fibre data for nutritional studies

Dietary fibre in processed murta (Ugni molinae Turcz) berries: bioactive components and antioxidant capacity

In this study the dietary fibre (DF) of fresh and processed murta berries was characterised with respect to bioactive and antioxidant properties. DF content was determined by three different methods (AOAC, dialysis membrane and indigestible fraction methods) comparing their effectiveness. The antioxidant activity of phenolic compounds (PC) in purée, fruit leather and isolated DF of murta berries was evaluated by DPPH and ORAC assays. Total phenolics and flavonoids linked to DF were determined by colorimetric tests, while PC profiles in the respective murta products were identified by HPLC. DF concentration was > 50 g/100 g dm, fluctuating between 52.03 ± 1.32 and 57.18 ± 0.61 g/100 g dm, exhibiting simultaneously high antioxidant activity, with ORAC values of 38,190 ± 661 and 26,425 ± 1399 µmol Trolox equivalent/100 g dm in the isolated DF of fresh murta berries and processed murta fruit leather respectively, which enabled a classification as antioxidant dietary fibre. Total phenolics and flavonoids linked to DF retained a high concentration in the fruit leather, implying a favourable effect of processing. Gallic acid and pyrogallol were found associated to DF, at a level of 34.03 ± 1.17 and 631.07 ± 22.10 mg/100 g dm in the fresh berries respectively, which conferred to murta berries a functional property not yet reported.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-022-05416-1.

Towards an improved global antioxidant response method (GAR+): Physiological-resembling in vitro digestion-fermentation method

The antioxidant capacity of food influences its shelf life and human health. To determine this parameter, the corresponding antioxidant species must first be extracted. Current methods don't adequately address this issue since they rely on extractions with organic solvents or on in vitro digestion without a subsequent fermentation. We present an improved protocol to determine the global antioxidant response of foods (GAR+) including both in vitro digestion and fermentation. All samples should be fermented with the same fresh faecal inoculum in order to decrease variability. In addition, the use of a pool of faeces from healthy donors is strongly recommended to improve repeatability. Although most antioxidant capacity is achieved after digestion, in some foods fermentation plays a role. Thus, the GAR+ method provides reliable values of the antioxidant capacity of foods that are closer to their in vivo activity by including the effects of gut microbiota over non-digested nutrients.

Dietary fiber intake of adolescents living in a boarding school in north-eastern part of Serbia: comparison of analyzed and calculated values

The total fiber intake in the adolescent population living in a boarding school was calculated using weighted food records and food composition tables. Total, insoluble, and soluble fiber daily intakes were also analyzed using the enzymatic-gravimetric method. The results were used to estimate the applicability of the calculation method to the Serbian diet pattern. The calculated total fiber daily intake was 28.8 ± 10.86 g/d in winter and 32.6 ± 13.68 g/d in summer season. Analyzed intakes of soluble fiber, insoluble fiber, and total fiber in the winter season were 4.2 ± 2.14 g/day, 29.7 ± 12.11 g/day, and 33.65 ± 11.374 g/day, respectively. In summer the season daily intakes were 3.4 ± 1.41 g/day for soluble fiber, 40.6 ± 16.65 g/day for insoluble fiber, and 43.57 ± 17.021 g/day for total fiber. The noticed differences for insoluble and soluble fibers between seasons were significant. The calculation method consistently gave lower values, both in winter and summer samples, in comparison with the enzymatic-gravimetric method, and the difference was on average -20.5% (P <0.05).

Regular consumption of a cocoa product improves the cardiometabolic profile in healthy and moderately hypercholesterolaemic adults

Cocoa products present great health potential due to their high content of polyphenols, mainly of flavanols. However, the antioxidant, anti-inflammatory and other health effects of regularly consuming cocoa products seem to depend on the intake and health status of the consumer, etc. and need to be further clarified. A randomised, controlled, cross-over, free-living study was carried out in healthy (n 24) and moderately hypercholesterolaemic (>2000 mg/l, n 20) subjects to assess the influence of regularly consuming (4 weeks) two servings (15 g each) of a cocoa product rich in fibre (containing 33·9 % of total dietary fibre (TDF) and 13·9 mg/g of soluble polyphenols) in milk v. consuming only milk (control) on (1) serum lipid and lipoprotein profile, (2) serum malondialdehyde levels, carbonyl groups, ferric reducing/antioxidant power, oxygen radical absorbance capacity and free radical-scavenging capacity, (3) IL-1β, IL-6, TNF-α, IL-10, IL-8, monocyte chemoattractant protein-1, and vascular and intracellular cell adhesion molecule levels, and (4) systolic and diastolic blood pressure and heart rate. Throughout the study, the diet and physical activity of the volunteers, as well as any possible changes in weight or other anthropometric parameters, were also evaluated. The intake of TDF increased (P< 0·001) to the recommended levels. Serum HDL-cholesterol (HDL-C) levels were increased (P< 0·001), whereas glucose (P= 0·029), IL-1β (P= 0·001) and IL-10 (P= 0·001) levels were decreased. The rest of the studied cardiovascular parameters, as well as the anthropometric ones, remained similar. In conclusion, regularly consuming a cocoa product with milk improves cardiovascular health by increasing HDL-C levels and inducing hypoglycaemic and anti-inflammatory effects in healthy and hypercholesterolaemic individuals without causing weight gain.

Effects of regularly consuming dietary fibre rich soluble cocoa products on bowel habits in healthy subjects: a free-living, two-stage, randomized, crossover, single-blind intervention

BACKGROUND

Dietary fibre is both preventive and therapeutic for bowel functional diseases. Soluble cocoa products are good sources of dietary fibre that may be supplemented with this dietary component. This study assessed the effects of regularly consuming two soluble cocoa products (A and B) with different non-starch polysaccharides levels (NSP, 15.1 and 22.0% w/w, respectively) on bowel habits using subjective intestinal function and symptom questionnaires, a daily diary and a faecal marker in healthy individuals.

METHODS

A free-living, two-stage, randomized, crossover, single-blind intervention was carried out in 44 healthy men and women, between 18-55 y old, who had not taken dietary supplements,laxatives, or antibiotics six months before the start of the study. In the four-week-long intervention stages, separated by a three-week-wash-out stage, two servings of A and B, that provided 2.26 vs. 6.60 g/day of NSP respectively, were taken. In each stage, volunteers' diet was recorded using a 72-h food intake report.

RESULTS

Regularly consuming cocoa A and B increased fibre intake, although only cocoa B significantly increased fibre intake (p < 0.001) with respect to the non-cocoa stage. No changes in body weight were observed in either of the 4 week interventions. With cocoa product B, the number of daily bowel movements increased (p = 0.002), the frequency of having a bowel movement once a day increased (p = 0.009), the time to have a bowel movement was lower (p = 0.016) as well as the feeling of constipation (p = 0.046) without inducing adverse gastrointestinal symptoms, only flatulence increased (p = 0.019).

CONCLUSIONS

Regular consumption of the cocoa products increases dietary fibre intake to recommended levels and product B improves bowel habits. The use of both objective and subjective assessments to evaluate the effects of food on bowel habits is recommended.

Metabolite production during in vitro colonic fermentation of dietary fiber: analysis and comparison of two European diets

Metabolite production and antioxidant released during colonic fermentation of naturally occurring dietary fiber (DF) from two European diets (Mediterranean and Scandinavian) were determined. With this aim, DF and associated components were isolated from both whole diets, as well as from cereals and fruits and vegetables comprising the diets. DF was used as substrate for colonic fermentation in a dynamic in vitro model of the colon, samples were collected, and fermentation metabolites were analyzed. Statistical differences between samples were observed in the concentrations of short-chain fatty acids and ammonia and in the ratio acetate/propionate/butyrate. Whole grain cereal DF generated a larger amount of propionate than refined flour cereal DF. Fruit and vegetable DF generated higher amounts of butyrate than cereal DF. Most antioxidant compounds were released from DF during in vitro colonic fermentation. It is concluded that different sources of DF may play a specific role in health maintenance mediated by metabolites produced during colonic fermentation.

Fiber concentrate from orange (Citrus sinensis L.) bagase: characterization and application as bakery product ingredient

Orange is a tropical fruit used in the juice industry, yielding important quantities of by products. The objective of this work was to obtain a dietary fiber-rich orange bagasse product (DFROBP), evaluate its chemical composition and its use in the preparation of a bakery product (muffin). Muffins containing two different levels of DFROBP were studied regarding chemical composition, in vitro starch digestibility, predicted glyceamic index and acceptability in a sensory test. DFROBP showed low fat and high dietary fiber contents. The soluble and insoluble dietary fiber fractions were balanced, which is of importance for the health beneficial effects of fiber sources. DFROBP-containing muffins showed the same rapidly digestible starch content as the reference muffin, whilst the slowly digestible starch level increased with the addition of DFROBP. However, the resistant starch content decreased when DFROBP increased in the muffin. The addition of DFROBP to muffin decreased the predicted glyceamic index, but no difference was found between the muffins prepared with the two DFROBP levels. The sensory score did not show difference between control muffin and that added with 10% of DFROBP. The addition of DFROBP to bakery products can be an alternative for people requiring low glyceamic response.

Antioxidant potential of rat plasma by administration of freeze-dried jaboticaba peel (Myrciaria jaboticaba Vell Berg)

The effect of the intake of freeze-dried jaboticaba peel powder on the antioxidant potential of rats' blood plasma was investigated in two experiments. In the first, 35 male rats, divided into 5 groups, received 7 mg of anthocyanins/100 g of body weight, by gavage. The blood was withdrawn 0, 30, 60, and 120 min after gavage. The antioxidant capacity was evaluated in plasma by ORAC and TEAC. There was no significant difference in the plasmatic antioxidant potential among the groups. In the second experiment, 40 male rats were divided into 4 groups that consumed, respectively, 0, 1, 2, and 4% of freeze-dried jaboticaba peel powder added to their diet. An increase in the plasmatic antioxidant potential was observed for groups that received 1 and 2% of jaboticaba peel powder (1.7 times by TEAC method and 1.3 times by ORAC); however, the group that received 4% of the powder did not show antioxidant effects according to the methods used.

Dietary fiber as a carrier of dietary antioxidants: an essential physiological function

The literature addresses dietary fiber (DF) and antioxidants (AOX) separately as nonrelated compounds. This paper proposes to show that DF and AOX could be approached jointly in nutrition and health studies because around 50% of the total dietary antioxidants, mainly polyphenolics, traverse the small intestine linked to dietary fiber. These antioxidants have received little attention so far. They release the fiber matrix in the colon by the action of the bacterial microbiota, producing metabolites and an antioxidant environment. The content of polyphenols associated with DF in different foods and their potential health-related properties, including animal experiments and human trials, are reviewed. It is concluded that the transportation of dietary antioxidants through the gastrointestinal tract may be an essential function of DF.

Definition of the Mediterranean diet based on bioactive compounds

Antioxidant (polyphenols and carotenoids) and nonantioxidant (phytosterols) bioactive compounds and dietary fiber may have a significant role in health. The intake of these compounds is strongly linked with the high consumption of fruits, vegetables, and unrefined cereals. A whole-diet approach to these food constituents is intended to render the current definition of Mediterranean diet based on food consumption more comprehensive. The Mediterranean dietary pattern can be characterized by the following four essential dietary indicators: 1) Monounsaturated to saturated fatty acid ratio (range: 1.6 to 2.0); 2) Intake of dietary fiber (41 to 62 g/person/day); 3) Antioxidant capacity of the whole diet (3500 to 5300 trolox equivalent/person/day); 4) Phytosterols intake (370 to 555 mg/person/day). The contribution of foods and beverages to these parameters is described. Spanish National Food Consumption Data for the years 2000 and 1964 were used to quantify the lowest and highest range values. The occurrence of these indicators in the Mediterranean diet has specific characteristics and there is sufficient scientific evidence to support the beneficial health effects.

Dietary fiber intake in two European diets with high (copenhagen, Denmark) and low (Murcia, Spain) colorectal cancer incidence

Contradictory results have been reported in studies associating dietary fiber (DF) intake and the incidence of colorectal cancer. Most studies focused mainly on the amount of total DF, but DF is a heterogeneous complex and its components are generally ignored. The aim of this work was to compare the amount and composition of DF intake in Murcia (Spain) and Copenhagen (Denmark). Total dietary fiber intake was a 31% higher in Murcia than in Copenhagen, the ratio of insoluble DF/soluble DF being similar in the two diets. DF in Murcia contains major amounts of nonstarch polysaccharides and polyphenolic compounds, mainly derived from the high consumption of fruits and vegetables (6.7 servings). Resistant starch intake was of the same order in the two regions while resistant protein intake was higher in Murcia. The quantitative and qualitative differences in DF intake may contribute to understand the differences in colorectal cancer incidence in Mediterranean and Scandinavian areas.

Effect of total replacement of pork backfat with walnut on the nutritional profile of frankfurters

The nutritional profile of a frankfurter with walnut (25%) (WF) was compared with that of low fat (6%) (LF) and normal fat (16%) (NF) sausages. LF frankfurters did not improve the fatty acid profile as compared with NF (p>0.05), or the indices of atherogenicity (IA) (0.50) or thrombogenicity (IT) (1.12), indicating that the reduction of animal fat produced no cardioprotective effect. However, frankfurter with walnut had a healthy polyunsaturated fatty acid profile, a lower ω-6/ω-3 ratio and lower IA (0.10) and IT (0.15). In addition, WF could be a good source of manganese, iron, copper, potassium and magnesium, supplying 39%, 35%, 34%, 16% and 15% of the respective daily recommended intakes, respectively. Also, there were significant amounts of other bioactive components such as α-,γ- and δ-tocopherol, total dietary fibre, polyphenols and tannins. The amino acid composition of WF indicated a healthier lysine/arginine ratio (0.83) than in LF (1.23) and NF (1.19).

Bioaccessibility of beta-carotene, lutein, and lycopene from fruits and vegetables

Epidemiological studies have consistently demonstrated that there is an association between carotenoid-rich food intakes with a low incidence in chronic diseases. Nevertheless, there is not an association between the intake of total dietary carotenoids and chronic health incidence in the European population, probably because of different carotenoid food sources and bioavailability. The objective of this study was to evaluate the small and large intestine bioaccessibilities of major dietary carotenoids from fruits and vegetables in a common diet. A bioaccessibility model that includes enzymatic digestion and in vitro colonic fermentation was employed. Lutein presented greater small intestine bioaccessibility (79%) than beta-carotene (27%) or lycopene (40%). With regard to large intestine bioaccessibility, similar amounts of lycopene and beta-carotene were released from the food matrix (57%), whereas small amounts of lutein (17%) were released. These results suggest that 91% of the beta-carotene, lutein, and lycopene contained in fruits and vegetables is available in the gut during the entire digestion process. Colonic fermentation is shown to be important for carotenoid availability in the gut.

Determination of beta-carotene and lutein available from green leafy vegetables by an in vitro digestion and colonic fermentation method

Green leafy vegetables (Spinacea oleracea, Cnidoscolus aconitifolius, and Solanum americanum) contain a high amount of beta-carotene (27-52 mg/100 g of dry sample) and lutein (140-193 mg/100 g of dry sample). The amount of beta-carotene and lutein released from the food matrix by the action of digestive enzymes ranged from 22 to 67% and from 27 to 77%, respectively. There was a significant correlation between the enzymatic release of carotenoids (lutein + beta-carotene) and the content of Klason lignin, nonstarch polysaccharides, and resistant protein. The carotenoids released by the in vitro colonic fermentation ranged from 2 to 11%, and part of them (0.251-4.03 mg/100 g of original dry sample) remained intact in the fermentation media and could be potentially absorbed in the colon. A significant part of carotenoids seems to be unavailable in the intestinal tract (16% in S. oleracea to 58% in C. aconitifolius).