Validating nutrient selection for product-group-specific nutrient indices for use as functional units in life cycle assessment of foods

The ability to provide adequate nutrition is considered a key factor in evaluating the sustainability of foods and diets. Nutrient indices are used as functional units (FU) in life cycle assessment of foods to include nutritional performance in the environmental assessment of a product. Several general and food-group-specific nutrient indices exist but many lack validation, particularly when used as FU. In addition, the nutrient selection strategies and reference units for nutrient intake can vary considerably among studies. To validate intake-based product-group-specific nutrient indices previously developed for protein (NR-FIprot) and carbohydrate (NR-FIcarb) foods and for fruits and vegetables (NR-FIveg), we applied principal component analysis to investigate correlations between nutrients in foods and dishes representing a typical Finnish diet. The reference amounts for meal components were based on a plate model that reflected Finnish dietary recommendations. The portion sizes for the different food groups were anchored at 100 g, 135 g and 350 g for proteins, carbohydrates and fruits/vegetables, respectively. Statistical modelling largely validated the NR-FI indices, highlighting protein foods as sources of niacin, vitamin B12 and Se, carbohydrate foods as sources of Mg, Fe and phosphorous, and fruits/vegetables as sources of potassium, vitamin K, vitamin C, fibre and thiamine. However, in contrast to the intake-based approach applied in NR-FIprot, the dietary recommendation-based validation process suggested that fruits and vegetables should be favoured as sources of riboflavin and vitamin B6.

True Ileal Amino Acid Digestibility and Protein Quality of 15N-Labeled Faba Bean in Healthy Humans

BACKGROUND

The recommended transition toward more plant-based diets, particularly containing legumes, requires a wider knowledge of plant protein bioavailability. Faba beans are cultivated at different latitudes and are used increasingly in human nutrition.

OBJECTIVES

We aimed to assess the nutritional quality of faba bean protein in healthy volunteers equipped with an intestinal tube to implement the ileal 15N balance method.

METHODS

Nine volunteers completed the study (7 males, 2 females, aged 33 ± 10 y, BMI: 24.7 ± 2.6 kg/m2). They were equipped with a nasoileal tube. After fasting overnight, they ingested a test meal consisting of cooked mash of dehulled faba bean seeds (20 g protein per serving of approximately 250 g) intrinsically labeled with 15N. Samples of ileal contents, plasma, and urine were collected over an 8-h postprandial period. Undigested nitrogen (N) and amino acids (AAs) were determined using isotopic MS, and subsequently, ileal digestibility and digestible indispensable amino acid score (DIAAS) were calculated. The measurement of postprandial deamination allowed calculation of the net postprandial protein utilization (NPPU).

RESULTS

The ileal N digestibility was 84.1% ± 7.7%. Postprandial deamination represented 19.2% ± 3.6% of ingested N, and the NPPU was 64.7% ± 9.7%. The ileal digestibility of individual AAs varied from 85.1% ± 13.7% for histidine to 94.2% ± 3.6% for glutamine + glutamate. The mean AA digestibility was ∼6 percentage points higher than the digestibility of N, reaching 89.8% ± 5.9%, whereas indispensable AA digestibility was 88.0% ± 7.3%. Histidine and tryptophan were the first limiting AAs [DIAAS = 0.77 (calculated by legume-specific N-to-protein conversion factor 5.4); 0.67 (by default factor 6.25)]. Sulfur AAs were limiting to a lesser extent [DIAA ratio = 0.94 (N × 5.4); 0.81 (N × 6.25)].

CONCLUSIONS

Protein ileal digestibility of cooked, dehulled faba beans in humans was moderate (<85%), but that of AAs was close to 90%. Overall protein quality was restricted by the limited histidine and tryptophan content. This trial was registered at clinicaltrials.gov as NCT05047757.

Partial substitution of red meat or processed meat with plant-based foods and the risk of colorectal cancer

OBJECTIVES

Shifting from animal-based to plant-based diets could reduce colorectal cancer (CRC) incidence. Currently, the impacts of these dietary shifts on CRC risk are ill-defined. Therefore, we examined partial substitutions of red or processed meat with whole grains, vegetables, fruits or a combination of these in relation to CRC risk in Finnish adults.

METHODS

We pooled five Finnish cohorts, resulting in 43 788 participants aged ≥ 25 years (79% men). Diet was assessed by validated food frequency questionnaires at study enrolment. We modelled partial substitutions of red (100 g/week) or processed meat (50 g/week) with corresponding amounts of plant-based foods. Cohort-specific hazard ratios (HR) for CRC were calculated using Cox proportional hazards models and pooled together using random-effects models. Adjustments included age, sex, energy intake and other relevant confounders.

RESULTS

During the median follow-up of 28.8 years, 1124 CRCs were diagnosed. We observed small risk reductions when red meat was substituted with vegetables (HR 0.97, 95% CI 0.95 - 0.99), fruits (0.97, 0.94 - 0.99), or whole grains, vegetables and fruits combined (0.97, 0.95 - 0.99). For processed meat, these substitutions yielded 1% risk reductions. Substituting red or processed meat with whole grains was associated with a decreased CRC risk only in participants with < median whole grain intake (0.92, 0.86 - 0.98; 0.96, 0.93 - 0.99, respectively; pinteraction=0.001).

CONCLUSIONS

Even small, easily implemented substitutions of red or processed meat with whole grains, vegetables or fruits could lower CRC risk in a population with high meat consumption. These findings broaden our insight into dietary modifications that could foster CRC primary prevention.

Polyphenol- and Glucuronoxylan-Rich Fiber Extract from Birch (Betula sp.) Wood Regulates Colonic Barrier Function and Cell Proliferation in Healthy Rats

Birch wood-derived fiber extracts containing glucuronoxylans (GX) and polyphenols show potential for various food technological applications. This study investigated the effect of two extracts, GXpoly and pureGX, differing in lignin content on colonic barrier function. Healthy rats were fed diets containing 10% GXpoly, pureGX, or cellulose for 4 weeks. Colon crypt depth was lower in the GX groups than in the control group, but in the proximal colon, the result was significant only in GXpoly. An artificial intelligence approach was established to measure the mucus content and goblet cells. In the distal colon, their amounts were higher in the control group than in the GX groups. All diets had a similar effect on the expression of the tight junction proteins occludin, claudin-1, and claudin-7. GXpoly enhanced the fecal IgA production. Our results suggest that GX-rich extracts could support the colonic barrier and work as functional food ingredients in the future.

Effects of partial replacement of red and processed meat with non-soya legumes on bone and mineral metabolism and amino acid intakes in BeanMan randomised clinical trial

The transition towards more plant-based diets may pose risks for bone health such as low vitamin D and Ca intakes. Findings for the contribution of animal and plant proteins and their amino acids (AA) to bone health are contradictory. This 6-week clinical trial aimed to investigate whether partial replacement of red and processed meat (RPM) with non-soya legumes affects AA intakes and bone turnover and mineral metabolism in 102 healthy 20-65-year-old men. Participants were randomly assigned to diet groups controlled for RPM and legume intake (designed total protein intake (TPI) 18 E%): the meat group consumed 760 g RPM per week (25 % TPI) and the legume group consumed non-soya legume-based products (20 % TPI) and 200 g RPM per week, the upper limit of the Planetary Health Diet (5 % TPI). No differences in bone (bone-specific alkaline phosphatase; tartrate-resistant acid phosphatase 5b) or mineral metabolism (25-hydroxyvitamin D; parathyroid hormone; fibroblast growth factor 23; phosphate and Ca) markers or Ca and vitamin D intakes were observed between the groups (P > 0·05). Methionine and histidine intakes were higher in the meat group (P ≤ 0·042), whereas the legume group had higher intakes of arginine, asparagine and phenylalanine (P ≤ 0·013). Mean essential AA intakes in both groups met the requirements. Increasing the proportion of non-soya legumes by reducing the amount of RPM in the diet for 6 weeks did not compromise bone turnover and provided on average adequate amounts of AA in healthy men, indicating that this ecologically sustainable dietary change is safe and relatively easy to implement.

Protein - a scoping review for Nordic Nutrition Recommendations 2023

Proteins are needed for providing essential amino acids, nitrogen, and fuel for the body's needs in all age groups. Proteins are especially required during active growth in pregnancy, lactation, childhood, and tissue growth in general. An adequate protein intake is needed in old adults to avoid premature muscle loss. According to the current dietary surveys, protein intake in the Nordic and Baltic countries varies from 15 to 19% of the total energy intake in adults. Comprehensive data regarding children and older adults are lacking. No good measure for protein status exists, and the estimation of physiological requirements is based on N-balance studies having some weaknesses. Protein quality is assessed by considering the protein digestibility of individual indispensable amino acids and their utilization (bioavailability), which is affected by food antinutrients and processing. The evidence regarding the association of protein intake per se with health outcomes is limited or suggestive. It is difficult to separate from the effect of other nutrients or ingredients in protein-rich foods. Proteins are widespread in foods, deriving from both animal and plant sources. Animal-sourced protein production puts more strain on the environment than plant-sourced proteins and contributes significantly to greenhouse gas emissions, thereby enhancing climate change. In Nordic and Baltic countries, consumption of animal-sourced proteins is relatively high. A shift toward more plant-based protein diets would be advisable for promoting a healthy and sustainable diet.

The impacts of partial replacement of red and processed meat with legumes or cereals on protein and amino acid intakes: a modelling study in the Finnish adult population

BACKGROUND

A shift towards more plant-based diets is considered healthy and environmentally sustainable but may cause a concern regarding protein and amino acid intakes. This modelling study aimed to assess the impacts of partial replacement of red and processed meat with legumes or cereals on the protein and indispensable amino acid intakes in the Finnish adult population.

MATERIALS AND METHODS

We used the cross-sectional data of the National FinDiet 2017 Survey (two non-consecutive 24-h recalls, n = 1655, 47% men, aged 18-74 years). Six replacement scenarios were created in which the amount of red and processed meat exceeding 70 g/day (Finnish nutrition recommendation), or 30 g/day (EAT-Lancet recommendation) was replaced with the same amounts of legumes, cereals or their combination. Differences to the reference diet were evaluated based on non-overlapping 95% confidence intervals. Population shares (%) below estimated average requirements (EAR) were calculated using the usual intake modelling methodology (SPADE).

RESULTS

The replacement scenarios decreased the protein and indispensable amino acid intakes depending on gender and age. At the 70-g level, decreases were observed only in men aged 18-64 years. At the 30-g level, decreases were observed in other gender and age groups except women aged 65-74 years. In the scenarios, the mean daily protein intake was 15-18% of total energy intake (E%) (reference 17-18 E%), and the proportions below the EAR were 7-10% in men and 8-10% in women aged 18-64 years (reference 5-7%) and 20-25% in men and 16-20% in women aged 65-74 years (reference 14-17%). For total indispensable amino acids, the proportions below the EAR were <5% in the reference diet and the scenarios.

CONCLUSIONS

The mean daily protein intake remained sufficient when red and processed meat was partially replaced with legumes or cereals in the Finnish adult population. However, protein adequacy in the elderly population warrants attention and more research.

Dietary fiber - a scoping review for Nordic Nutrition Recommendations 2023

Dietary fiber is a term crudely defined as carbohydrates (CHOs) that escape digestion and uptake in the small intestine. Lignin, which is not a CHO, is also a part of the dietary fiber definition. Dietary fibers come in different sizes and forms, with a variety of combinations of monomeric units. Health authorities worldwide have for many years recommended a diet rich in dietary fibers based on consistent findings that dietary fibers are associated with reduced incidences of major non-communicable diseases, including obesity, type 2 diabetes, cardiovascular disease, and colorectal cancer. Most fibers come from common edible foods from the plant kingdom, but fibers are also found in food additives, supplements, and breast milk. The recommended intake in Nordic Nutrition Recommendations 2012 (NNR2012) is 25 g/d for women and 35 g/d for men, whereas the actual intake is significantly lower, ranging from 16 g/d to 22 g/d in women and 18 g/d to 26 g/d in men. New studies since NNR2012 confirm the current view that dietary fiber is beneficial for health, advocating intakes of at least 25 g/day.

Metabolic Fate of Lignin in Birch Glucuronoxylan Extracts as Dietary Fiber Studied in a Rat Model

SCOPE

While previously considered inert, recent studies suggest lignin metabolism with unknown metabolic fates is occurring in the gastrointestinal tract of several animal models. This study focuses on analyzing the potential metabolites of lignin.

METHODS AND RESULTS

The diets of rats include relatively pure birch glucuronoxylan (pureGX) with residual lignin or lignin-rich GX (GXpoly) in their diet. Nuclear magnetic spectroscopy of the lignin isolated from the GXpoly-fed rats fecal sample shows high alteration in chemical structure, whereas lignin-carbohydrate complexes (LCCs) are enriched in fecal samples from the pureGX group. Moreover, the increased syringyl-to-guaiacyl (S/G) ratio suggests that lignin G-units are predominantly metabolized based on pyrolysis gas chromatography-mass spectrometry (pyr-GC/MS). The presence of small phenolic metabolites identified in urine samples of the GXpoly group, for example, ferulic and sinapic acids, their sulfate and glucuronide derivatives, and 4-sulfobenzylalcohol, suggests that the small fragmented lignin metabolites in the large intestine enter the plasma, and are further processed in the liver. Finally, the relative abundances of polyphenol-degrading Enterorhabdus and Akkermansia in the gut microbiota are associated with lignin metabolism.

CONCLUSION

These findings give further evidence to lignin metabolism in the gut of nonruminants and provide insight to the potential microbes and metabolic routes.

Barriers associated with pulse and plant-based meat alternative consumption across sociodemographic groups: a Capability, Opportunity, Motivation, Behaviour model approach

Introduction

To enhance environmental sustainability and food security, there should be a change in dietary protein consumption. It is suggested that meat consumption should be reduced and that the currently low consumption of pulses and other plant-based proteins should increase. We aimed to examine (1) how sociodemographic factors and perceived barriers are associated with self-reported current and perceived future pulse and other plant-based meat alternative (PBMA) consumption and (2) how sociodemographic factors relate to perceived barriers.

Methods

Participants were 18-75 year-old Finnish adults (n = 1,000). Multivariable logistic regression was used as the main analysis technique. The results were interpreted by employing the Capability, Opportunity, Motivation, Behaviour (COM-B) model.

Results

Pulses were consumed more often than PBMAs and lower education level and financial strain were associated with more infrequent pulse and PBMA use. The most common perceived barriers for pulse consumption were unfamiliarity, expensive price, and unpleasant taste, which can be interpreted to represent the capability, opportunity and motivation components of the COM-B model, respectively. Women, the young, and financially strained perceived more barriers limiting their pulse consumption than others.

Discussion

To increase plant-based food consumption, it is important that tasty, easy to use and affordable plant-based foods are available for all. Additionally, we suggest that food services should be encouraged to increase the use of pulses in their dishes and that capabilities, opportunities and motivations are taken into account in intervention measures advancing plant protein consumption.

Associations of dietary patterns with common infections and antibiotic use among Finnish preschoolers

Background

Preschoolers suffer frequently from infections. Although nutrition plays a key role in immune function, very little is known about the impact of overall diet on preschoolers' infections.

Objective

To assess the associations between dietary patterns, common infections and antibiotic use among Finnish preschoolers.

Design

The study included 721 3-6-year-old preschoolers participating in the cross-sectional DAGIS survey. Parents retrospectively reported the number of common colds, gastroenteritis episodes and antibiotic courses their children had acquired during the past year. Food consumption outside preschool hours was recorded using a food frequency questionnaire. Dietary patterns were derived from the consumption frequencies using principal component analysis. Associations between the thirds of the dietary pattern scores and the outcomes were analysed using logistic and negative binomial regression models.

Results

Prevalence of common colds was lower in moderate and high adherence to the sweets-and-treats pattern than in low adherence (prevalence ratio [PR]: 0.89, 95% confidence interval [CI]: 0.80-1.00, and PR: 0.88, 95% CI: 0.79-0.99, respectively) and higher in high adherence to the health-conscious pattern than in low adherence (PR: 1.13, 95% CI: 1.01-1.27) after adjusting for age, sex, number of children living in the same household, frequency of preschool attendance, family's highest education and probiotic use. The risk of ≥1 gastroenteritis episode and the prevalence of antibiotic courses were lower in moderate adherence to the sweets-and-treats pattern than in low adherence (odds ratio [OR]: 0.63, 95% CI: 0.44-0.92 and PR: 0.77, 95% CI: 0.59-1.00, respectively).

Conclusions

The results were unexpected. Parents who were most health-conscious of their children's diet might also have been more aware of their children's illness.

Partial substitution of red or processed meat with plant-based foods and the risk of type 2 diabetes

High consumption of red and processed meat has been associated with increased type 2 diabetes (T2D) risk. These kinds of diets are also environmentally unsustainable. We examined a modeled association between a partial substitution of red meat or processed meat with plant-based foods (legumes, vegetables, fruit, cereals, or a combination of these) and T2D risk among Finnish adults. We used pooled data from five Finnish cohorts (n = 41,662, 22% women, aged ≥ 25 years, 10.9 years median follow-up with 1750 incident T2D cases). Diet was assessed by a validated food frequency questionnaire. In the substitution models, 100 g/week of red meat or 50 g/week of processed meat were substituted with similar amounts of plant-based substitutes. Cohort-specific hazard ratios (HRs) were estimated by Cox proportional hazards multivariable model and pooled using a two-staged random-effects model. We observed small, but statistically significant, reductions in T2D risk in men when red or processed meat were partially substituted with fruits (red meat: HR 0.98, 95% CI 0.97-1.00, P = 0.049, processed meat: 0.99, 0.98-1.00, P = 0.005), cereals (red meat: 0.97, 0.95-0.99, P = 0.005, processed meat: 0.99, 0.98-1.00, P = 0.004) or combination of plant-based foods (only processed meat: 0.99, 0.98-1.00, P = 0.004) but not with legumes or vegetables. The findings of women were similar but not statistically significant. Our findings suggest that even small, easily implemented, shifts towards more sustainable diets may reduce T2D risk particularly in men.

Abstract 4228: Replacing red and processed meat with legumes modulates gut microbiome and microbiota-related metabolites linked to gut health and cancer prevention in healthy working-aged men

Background and Aim: Changing dietary habits have great potential for colorectal cancer (CRC) prevention. Regardless of the accumulated evidence on the relationship between dietary protein sources and CRC, the explaining mechanisms remain not well established. Diet-delivered microbial metabolites such as secondary bile acids (BA), N-nitroso compounds (NOC), trimethylamine N-oxide (TMAO), short-chain fatty acid (SCFA), and branched-chain fatty acids (BCFA) have been suggested to mediate the relationship. The aim of this study was to examine the effects of partial replacement of red and processed meat (RPM), associated with higher CRC risk, with legumes on the fecal microbiota composition and metabolite profiles in healthy men.

Methods: The study was a partly controlled 6-wk parallel design randomized clinical trial (n=102, age 37 y (range 21 - 61 y), BMI 25.5 ± 3.3 kg/m2) with two groups following either a diet supplemented with RPM (meat group) or a diet supplemented with legumes and RPM (legume group). The amount of RPM (200 g/wk) in the legume group was based on the maximum amount recommended by the EAT-Lancet Commission whereas the amount in the meat group (760 g/wk) corresponded the average intake of Finnish men. Fecal SCFAs (µg/ml) and BCFAs (µg/ml) were analyzed with GS-MS, BAs (arbitrary, analyte/standard ratios) with UHPLC-MS/MS, and NOCs (pmol/mg) with selective de-nitrosation and chemiluminescence-based detection. Urine TMAO was quantified by NMR and fecal microbiota composition was analyzed using 16S rRNA amplicon sequencing techniques. Dietary intakes were analyzed with 4-day food records.

Results: At the baseline, no significant differences (p &gt; 0.05) were reported in age, BMI, dietary intake of total fiber (g/d), protein (E%), fat (E%), or in the fecal metabolites. The legume group had more pronounced effects on the gut microbiota community level, indicating ecosystem level differences. Total NOCs (p &lt; 0.0001) and heme-originated NOCs (FeNO; p &lt; 0.0001) were smaller in the legume group than in the meat group. Significant differences between the groups were observed in intake of total fiber (p &lt; 0.001), cholesterol (mg/d, p &lt; 0.001), saturated (p &lt; 0.005), and polyunsaturated fat (p &lt; 0.001). Although not significant (p &gt; 0.05), total, secondary and unconjugated BAs, and total BCFA were higher in the meat group, whereas primary and conjugated BAs and total SCFAs were higher in the legume group. The concentration of total SCFA and individual SCFA decreased in both groups during the intervention period. Overall, a large sample-to-sample variation was observed.

Conclusions: The results indicate that partial replacement of RPM with legume products can potentially change microbiota activity and gut metabolites, suggesting a protective gut metabolic profile against colorectal cancer.

Citation Format: Tuulia Pietilä, Isabell Schreck, Tiina Pellinen, Johanna Vauhkonen, Essi Päivärinta, Mikko Neuvonen, Mikko Niemi, Anne Salonen, Anne-Maria Pajari. Replacing red and processed meat with legumes modulates gut microbiome and microbiota-related metabolites linked to gut health and cancer prevention in healthy working-aged men. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4228.

Partial replacement of red and processed meat with legumes: a modelling study of the impact on nutrient intakes and nutrient adequacy on the population level

OBJECTIVE

The shift towards plant-based diets with less meat and more legumes is a global target and requires an understanding of the consequences of dietary adequacy on the population level. Our aim was to model the impact of partial replacement of red and processed meat with legumes on nutrient intakes and population shares below dietary reference intakes.

DESIGN

Modelling study with three scenarios anchored in meat cut-offs: ≤ 70 g/d (Finnish dietary guideline); ≤ 50 g/d (Danish dietary guideline); ≤ 30 g/d (EAT-Lancet recommendation). In all subjects, the amount of meat in grams over the cut-off was replaced with the same amount of legumes. The SPADE method was used to model usual intake distributions. Meaningful differences in average intakes and in population shares below dietary reference intakes compared to the reference (FinDiet) were evaluated based on non-overlapping 95 % CI.

SETTING

Finnish national food consumption survey (FinDiet 2017).

SUBJECTS

Finnish adults (n 1655) aged18-74 years (47 % men).

RESULTS

The scenarios introduced increases in the average intakes of fibre, folate, K, Mg, Cu and Fe, and decreases in intakes of saturated fat, niacin, vitamin B12, Se and Zn. Meaningful shifts of the usual intake distributions of fibre and folate towards improvement in intakes emerged already in 'scenario 70 g'. Overall, distribution shifts towards a higher probability of inadequate intakes of the studied nutrients were not observed.

CONCLUSIONS

These results support the public health message to partly replace meat with legumes and may benefit nutrition policy actions towards sustainable diets in the Nordic countries and beyond.

Unique Pakistani gut microbiota highlights population-specific microbiota signatures of type 2 diabetes mellitus

Biogeographic variations in the gut microbiota are pivotal to understanding the global pattern of host-microbiota interactions in prevalent lifestyle-related diseases. Pakistani adults, having an exceptionally high prevalence of type 2 diabetes mellitus (T2D), are one of the most understudied populations in microbiota research to date. The aim of the present study is to examine the gut microbiota across individuals from Pakistan and other populations of non-industrialized and industrialized lifestyles with a focus on T2D. The fecal samples from 94 urban-dwelling Pakistani adults with and without T2D were profiled by bacterial 16S ribosomal RNA gene and fungal internal transcribed spacer (ITS) region amplicon sequencing and eubacterial qPCR, and plasma samples quantified for circulating levels of lipopolysaccharide-binding protein (LBP) and the activation ability of Toll-like receptor (TLR)-signaling. Publicly available datasets generated with comparable molecular methods were retrieved for comparative analysis of the bacterial microbiota. Overall, urbanized Pakistanis' gut microbiota was similar to that of transitional or non-industrialized populations, depleted in Akkermansiaceae and enriched in Prevotellaceae (dominated by the non-Westernized clades of Prevotella copri). The relatively high proportion of Atopobiaceae appeared to be a unique characteristic of the Pakistani gut microbiota. The Pakistanis with T2D had elevated levels of LBP and TLR-signaling in circulation as well as gut microbial signatures atypical of other populations, e.g., increased relative abundance of Libanicoccus/Parolsenella, limiting the inter-population extrapolation of gut microbiota-based classifiers for T2D. Taken together, our findings call for a more global representation of understudied populations to extend the applicability of microbiota-based diagnostics and therapeutics.

Correction: Gut microbiota can utilize prebiotic birch glucuronoxylan in production of short-chain fatty acids in rats

Correction for 'Gut microbiota can utilize prebiotic birch glucuronoxylan in production of short-chain fatty acids in rats' by Emma Kynkäänniemi et al., Food Funct., 2022, 13, 3746-3759, DOI: 10.1039/D1FO03922A.

Gut microbiota can utilize prebiotic birch glucuronoxylan in production of short-chain fatty acids in rats

Birch-derived polyphenol and fiber (glucuronoxylan, GX)-rich extract and highly purified GX-rich extract support the growth of beneficial gut bacteria, suppress the harmful ones, and increase the production of total short-chain fatty acids (SCFA).

Replacing dietary animal-source proteins with plant-source proteins changes dietary intake and status of vitamins and minerals in healthy adults: a 12-week randomized controlled trial

PURPOSE

A shift towards more plant-based diets promotes both health and sustainability. However, controlled trials addressing the nutritional effects of replacing animal proteins with plant proteins are lacking. We examined the effects of partly replacing animal proteins with plant proteins on critical vitamin and mineral intake and statuses in healthy adults using a whole-diet approach.

METHODS

Volunteers aged 20-69 years (107 female, 29 male) were randomly allocated into one of three 12-week intervention groups with different dietary protein compositions: ANIMAL: 70% animal-source protein/30% plant-source protein; 50/50: 50% animal/50% plant; PLANT: 30% animal/70% plant; all with designed protein intake of 17 E%. We analysed vitamin B-12, iodine, iron, folate, and zinc intakes from 4-day food records, haemoglobin, ferritin, transferrin receptor, folate, and holotranscobalamin II from fasting blood samples, and iodine from 24-h urine.

RESULTS

At the end point, vitamin B-12 intake and status were lower in PLANT than in 50/50 or ANIMAL groups (P ≤ 0.007 for all). Vitamin B-12 intake was also lower in 50/50 than in ANIMAL (P < 0.001). Iodine intake and status were lower in both 50/50 and PLANT than in ANIMAL (P ≤ 0.002 for all). Iron and folate intakes were higher in PLANT than in ANIMAL (P < 0.001, P = 0.047), but no significant differences emerged in the respective biomarkers.

CONCLUSIONS

Partial replacement of animal protein foods with plant protein foods led to marked decreases in the intake and status of vitamin B-12 and iodine. No changes in iron status were seen. More attention needs to be paid to adequate micronutrient intakes when following flexitarian diets.

CLINICAL TRIAL REGISTRY

NCT03206827; registration date: 2017-06-30.

Fecal Bacteria Implicated in Biofilm Production Are Enriched and Associate to Gastrointestinal Symptoms in Patients With APECED - A Pilot Study

Backgrounds and Aims

APECED is a rare autoimmune disease caused by mutations in the Autoimmune Regulator gene. A significant proportion of patients also have gastrointestinal symptoms, including malabsorption, chronic diarrhea, and obstipation. The pathological background of the gastrointestinal symptoms remains incompletely understood and involves multiple factors, with autoimmunity being the most common underlying cause. Patients with APECED have increased immune responses against gut commensals. Our objective was to evaluate whether the intestinal microbiota composition, predicted functions or fungal abundance differ between Finnish patients with APECED and healthy controls, and whether these associate to the patients' clinical phenotype and gastrointestinal symptoms.

Methods

DNA was isolated from fecal samples from 15 patients with APECED (median age 46.4 years) together with 15 samples from body mass index matched healthy controls. DNA samples were subjected to analysis of the gut microbiota using 16S rRNA gene amplicon sequencing, imputed metagenomics using the PICRUSt2 algorithm, and quantitative PCR for fungi. Extensive correlations of the microbiota with patient characteristics were determined.

Results

Analysis of gut microbiota indicated that both alpha- and beta-diversity were altered in patients with APECED compared to healthy controls. The fraction of Faecalibacterium was reduced in patients with APECED while that of Atopobium spp. and several gram-negative genera previously implicated in biofilm formation, e.g. Veillonella, Prevotella, Megasphaera and Heamophilus, were increased in parallel to lipopolysaccharide (LPS) synthesis in imputed metagenomics. The differences in gut microbiota were linked to patient characteristics, especially the presence of anti-Saccharomyces cerevisiae antibodies (ASCA) and severity of gastrointestinal symptoms.

Conclusions

Gut microbiota of patients with APECED is altered and enriched with predominantly gram-negative bacterial taxa that may promote biofilm formation and lead to increased exposure to LPS in the patients. The most pronounced alterations in the microbiota were associated with more severe gastrointestinal symptoms.

Partial Replacement of Animal Proteins with Plant Proteins for 12 Weeks Accelerates Bone Turnover Among Healthy Adults: A Randomized Clinical Trial

BACKGROUND

Plant-based diets may reduce the risk of chronic diseases, but can also lead to low calcium and vitamin D intakes, posing a risk for bone health.

OBJECTIVES

We investigated whether partial replacement of animal proteins with plant-based proteins using a whole-diet approach affects bone and mineral metabolism in healthy adults in 3 groups fed diets differing in protein composition.

METHODS

This 12-week clinical trial was comprised of 107 women and 29 men (20-69 years old; BMI mean ± SD, 24.8 ± 3.9) randomly assigned to consume 1 of 3 diets designed to provide 17 energy percent (E%) protein: "animal" (70% animal protein, 30% plant protein of total protein intake), "50/50" (50% animal, 50% plant), and "plant" (30% animal, 70% plant) diets. We examined differences in bone formation [serum intact procollagen type I amino-terminal propeptide (S-iPINP)], bone resorption [serum collagen type 1 cross-linked C-terminal telopeptide (S-CTX)], mineral metabolism markers (primary outcomes), and nutrient intakes (secondary outcomes) by ANOVA/ANCOVA.

RESULTS

S-CTX was significantly higher in the plant group (mean ± SEM, 0.44 ± 0.02 ng/mL) than in the other groups (P values < 0.001 for both), and differed also between the animal (mean ± SEM, 0.29 ± 0.02 ng/mL) and 50/50 groups (mean ± SEM, 0.34 ± 0.02 ng/mL; P = 0.018). S-iPINP was significantly higher in the plant group (mean ± SEM, 63.9 ± 1.91 ng/mL) than in the animal group (mean ± SEM, 55.0 ± 1.82 ng/mL; P = 0.006). In a subgroup without a history of vitamin D supplement use, plasma parathyroid hormone was significantly higher in the plant than in the animal group (P = 0.018). Vitamin D and calcium intakes were below recommended levels in the plant group (mean ± SEM, 6.2 ± 3.7 μg/d and 733 ± 164 mg/d, respectively).

CONCLUSIONS

Partial replacement of animal proteins with plant-based proteins for 12 weeks increased the markers of bone resorption and formation among healthy adults, indicating a possible risk for bone health. This is probably caused by lower vitamin D and calcium intakes from diets containing more plant-based proteins, but it is unclear whether differences in protein intake or quality play a major role. This trial was registered at clinicaltrials.gov as NCT03206827.

Abstract 965: Effects of replacing dietary animal protein with plant-based protein on the formation of intestinal N-nitroso compounds (NOCs) and biomarkers of colon cancer in healthy adults–a 12-week intervention study

Epidemiological studies have indicated that high consumption of red and processed meats and low consumption of fiber-rich and plant-based foods are associated with an increased risk for colorectal cancer. Here we aimed to investigate whether partial replacement of dietary animal proteins with plant-based proteins changes gut metabolism and markers for colon cancer risk. We carried out a 12-week partly controlled clinical intervention study with following diets: 1) 70% of proteins from animal-based sources and 30% from plant-based sources, representing habitual Finnish/Western diet at the moment 2) 50% animal and 50% plant-based protein sources and 3) 30% animal and 70% plant-based proteins. Protein intake on all diets was planned to be 17 E% and the actual intake was analyzed using 4-day food records before and at the end of the intervention. Healthy, 20-69-year old participants (n=136) were randomly allocated to intervention groups. Participants collected stool samples before and at the end of the intervention. Fecal water was extracted and its effect on the viability of human colon carcinoma cells after 24h exposure was determined using cck-8 reagent. A 1:5 fecal homogenate was prepared and analyzed for total and heme-derived NOCs using selective de-nitrosation and detection by Ecomedics CLD 88 Exhalyzer. A separate spot stool sample was collected for gut microbiota analyses. At the end of the intervention, the viability of HCA7 colon carcinoma cells exposed to fecal water was significantly lower (P=0.005 ANCOVA) in the most plant-based diet group in comparison to group 1 (29.9% vs. 37.7%, P=0.011) and group 2 (29.9% vs. 37.1%, P=0.021). The concentrations of total NOCs (groups 1: 4.0 ± 2.4, 2: 3.1 ± 1.8, 3: 2.7 ± 1.5 pmol/mg faeces; 1 vs. 2 P=0.056, 1 vs. 3 P=0.001) and heme-derived NOCs (1: 2.5 ± 1.9, 2: 1.8 ± 1.4, 3: 1.4 ± 0.9 pmol/mg faeces; 1 vs. 2 P=0.055, 1 vs. 3 P&lt;0.001) decreased in a dose-dependent manner when dietary animal protein was replaced with plant protein sources. Even though the protein intake was somewhat lower in group 3 (14.5 E%, P&lt;0.001) than in group 1 (17.6 E%), it is unlikely to explain the results. Diets rich in plant-based proteins and scarce in red and processed meat may provide a cancer-preventive metabolic environment in the gut and thus decrease the risk for colorectal cancer.

Citation Format: Anne-Maria Pajari, Essi Päivärinta, Vesa Lapinkero, Jessica Manngård, Tiina Pellinen, Suvi Itkonen, Anne Salonen. Effects of replacing dietary animal protein with plant-based protein on the formation of intestinal N-nitroso compounds (NOCs) and biomarkers of colon cancer in healthy adults–a 12-week intervention study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 965.

Western diet enhances intestinal tumorigenesis in Min/+ mice, associating with mucosal metabolic and inflammatory stress and loss of Apc heterozygosity

Western-type diet (WD) is a risk factor for colorectal cancer, but the underlying mechanisms are poorly understood. We investigated the interaction of WD and heterozygous mutation in the Apc gene on adenoma formation and metabolic and immunological changes in the histologically normal intestinal mucosa of Apc^Min/+ (Min/+) mice. The diet used was high in saturated fat and low in calcium, vitamin D, fiber and folate. The number of adenomas was twofold higher in the WD mice compared to controls, but adenoma size, proliferation or apoptosis did not differ. The ratio of the Min to wild-type allele was higher in the WD mice, indicating accelerated loss of Apc heterozygosity (LOH). Densities of intraepithelial CD3ε⁺ T lymphocytes and of mucosal FoxP3⁺ regulatory T cells were higher in the WD mice, implying inflammatory changes. Western blot analyses from the mucosa of the WD mice showed suppressed activation of the ERK and AKT pathways and a tendency for reduced activation of the mTOR pathway as measured in phosphoS6/S6 levels. The expression of pyruvate dehydrogenase kinase 4 was up-regulated in both mRNA and protein levels. Gene expression analyses showed changes in oxidation/reduction, fatty acid and monosaccharide metabolic pathways, tissue organization, cell fate and regulation of apoptosis. Together, our results suggest that the high-risk Western diet primes the intestine to tumorigenesis through synergistic effects in energy metabolism, inflammation and oxidative stress, which culminate in the acceleration of LOH of the Apc gene.

Ellagitannin-rich cloudberry inhibits hepatocyte growth factor induced cell migration and phosphatidylinositol 3-kinase/AKT activation in colon carcinoma cells and tumors in Min mice

Berries have been found to inhibit colon carcinogenesis in animal models, and thus represent a potential source of compounds for prevention and treatment of colorectal cancer. The mechanistic basis for their effects is not well understood. We used human colon carcinoma cells and Min mice to investigate the effects of ellagitannin-rich cloudberry (Rubus chamaemorus) extract on cancer cell migration and underlying cell signaling. Intrinsic and hepatocyte growth factor (HGF) -induced cell motility in human HT29 and HCA7 colon carcinoma cells was assessed carrying out cell scattering and scratch wound healing assays using time-lapse microscopy. Activation of Met, AKT, and ERK in cell lines and tumors of cloudberry-fed Min mice were determined using immunoprecipitation, Western blot and immunohistochemical analyses. Cloudberry extract significantly inhibited particularly HGF-induced cancer cell migration in both cell lines. Cloudberry extract inhibited the Met receptor tyrosine phosphorylation by HGF and strongly suppressed HGF-induced AKT and ERK activation in both HT29 and HCA7 cells. Consistently, cloudberry feeding (10% w/w freeze-dried berries in diet for 10 weeks) reduced the level of active AKT and prevented phosphoMet localization at the edges in tumors of Min mice. These results indicate that cloudberry reduces tumor growth and cancer cell motility by inhibiting Met signaling and consequent activation of phosphatidylinositol 3-kinase/AKT in vitro and in tumors in vivo. As the Met receptor is recognized to be a major target in cancer treatment, our results suggest that dietary phytochemicals may have therapeutic value in reducing cancer progression and metastasis.

[Risk factors and possibilities of prevention of bowel cancer]

The incidence of bowel cancer has doubled over the past 50 years. Although the treatment outcome has improved, 40% of those affected with the disease still die from it. Treatment in the terminal phase of the disease is expensive and requires plenty of resources without resulting in patient recovery. Bowel cancer could theoretically be reduced by changing the living habits. Focusing of endoscopy resources to screening of symptomless patients would be a more realistic means. Because bowel cancer develops through an endoscopically detectable and slow-growing precancerous adenoma, it is possible to reduce massive disease burden through screening.

Plant sterol feeding induces tumor formation and alters sterol metabolism in the intestine of Apc(Min) mice

Dietary plant sterols reduce the absorption of cholesterol and therefore increase intraluminal cholesterol concentration. We examined how plant sterol esters from functional foods affect intestinal tumorigenesis in tumor-prone adenomatous polyposis coli (Apc)(Min) mice. Feeding plant sterols at 0.8% increased the number of intestinal adenomas, and the effect was significant in female mice. The concentration of mucosal free sitosterol increased by eightfold in plant sterol males and by threefold in plant sterol females when compared with respective controls. The concentration of mucosal free cholesterol was significantly lower in plant sterol males than in control males, and the decrease in free cholesterol was accompanied with a significant increase in nuclear sterol regulatory element binding protein-2. No difference was found in the levels of β-catenin, cyclin D1, epidermal growth factor receptor, extracellular signal-regulated kinase 1/2, or caveolin-1 in either gender after plant sterol feeding. Among all measured parameters, higher levels of estrogen receptor β and free cholesterol in the mucosa were among the strongest predictors of increased intestinal tumorigenesis. In addition, gene expression data showed significant enrichment of up-regulated genes of cell cycle control and cholesterol biosynthesis in plant sterol females. The results indicate that high intake of plant sterols accelerates intestinal tumorigenesis in female Apc (Min)mice; however, the mechanism behind the adverse effect remains to be discovered.

Abstract 4871: Berry feeding changes gut microbiota and immune function in association with adenoma formation in the Min mouse

In the gut, the interaction between the tumor tissue and its microenvironment including the microbiota and immune cells may play a significant role in the carcinogenic process. Here we studied whether the anti-carcinogenic effects of berry diets were mediated by changes in the gut microbiota and immune cells. Male and female Min mice were fed modified high-fat AIN93-G diets containing 10% (w/w) freeze-dried bilberry or cloudberry for 10 weeks. The control diet was similar but without any berries. Mucosal B and T lymphocytes were analysed using immunohistochemical staining. The microbial profile was determined carrying out PCR-DGGE analysis using bacterial genomic DNA extracted from caecal contents.

Microbial PCR-DGGE profiles contained 10-19 amplicons, indicating that the microbiota in the mouse cecum contents is diverse. According to their PCR-DGGE patterns, samples of control and cloudberry-fed mice could be divided to well-defined subgroups both visually and using Molecular Analyst software. Instead, visual grouping of the samples of bilberry-fed mice was impossible and the samples were only grouped using the software. In the control mice, amplicons a-d were present in all samples but on the basis of their intensity, amplicons b-d represented the dominant species. In the cloudberry mice, amplicons a, c, d, e and f existed in all samples but some of them lacked a pronounced amplicon b. In the bilberry mice, the amplicons a-e existed in all samples. In addition, bilberry samples contained amplicon g that seemed to be more prevalent and intense than in the samples of the other two groups. The amplicon g was sequenced and found to belong to the Clostridiales order of the Clostridia class in the Firmicutes phylum and to represent an uncultured bacterium clone abc21b07.x1: AY667976.

Cloudberry feeding resulted in a smaller density of mucosal CD3+ T lymphocytes (p=0.149) and a significantly smaller ratio of intraepithelial to total CD3+ T lymphocytes (p=0.034) when compared to the control group. Furthermore, there was a significant positive correlation (p=0.012) between the ratio of intraepithelial to total CD3+ T lymphocytes and adenoma burden in the small intestine of Min mice. Interestingly, no difference in the density of any lymphocytes was found between the bilberry and the control group. Berry feeding did not affect the density of B lymphocytes in the intestinal mucosa.

Here we show that berry feeding changes the microbiota and the distribution of immune cells in the intestine of Min mice and these changes are associated with adenoma formation.

Citation Format: Anne-Maria Pajari, Essi Paivarinta, Johanna Maukonen, Mikael Niku, Anu Heiman-Lindh, Maria Saarela, Marja Mutanen. Berry feeding changes gut microbiota and immune function in association with adenoma formation in the Min mouse. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4871. doi:10.1158/1538-7445.AM2013-4871

Plant stanols induce intestinal tumor formation by up-regulating Wnt and EGFR signaling in Apc Min mice

The rate of APC mutations in the intestine increases in middle-age. At the same period of life, plant sterol and stanol enriched functional foods are introduced to diet to lower blood cholesterol. This study examined the effect of plant stanol enriched diet on intestinal adenoma formation in the Apc(Min) mouse. Apc(Min) mice were fed 0.8% plant stanol diet or control diet for nine weeks. Cholesterol, plant sterols and plant stanols were analyzed from the caecum content and the intestinal mucosa. Levels of β-catenin, cyclin D1, epidermal growth factor receptor (EGFR) and extracellular signal-regulated kinase 1/2 (ERK1/2) were measured from the intestinal mucosa by Western blotting. Gene expression was determined from the intestinal mucosa using Affymetrix and the data were analyzed for enriched categories and pathways. Plant stanols induced adenoma formation in the small intestine, however, the adenoma size was not affected. We saw increased levels of nuclear β-catenin, phosphorylated β-catenin (Ser675 and Ser552), nuclear cyclin D1, total and phosphorylated EGFR and phosphorylated ERK1/2 in the intestinal mucosa after plant stanol feeding. The Affymetrix data demonstrate that several enzymes of cholesterol synthesis pathway were up-regulated, although the cholesterol level in the intestinal mucosa was not altered. We show that plant stanols induce adenoma formation by activating Wnt and EGFR signaling. EGFR signaling seems to have promoted β-catenin phosphorylation and its translocation into the nucleus, where the expression of cyclin D1 was increased. Up-regulated cholesterol synthesis may partly explain the increased EGFR signaling in the plant stanol-fed mice.

Abstract 4374: Plant stanols induce the formation of intestinal adenomas and activate ERK1 signaling in the ApcMin/+ mouse

Introduction

The incidence of colorectal cancer (CRC) has been increasing in many Western countries for several decades. Diet rich in plant foods is known to decrease CRC risk, whereas high intake of fat and cholesterol is associated with an increased risk. Plant sterols have been shown to inhibit colon cancer cell growth in vitro (Awad et al. 1996, Choi et al. 2003).

The ApcMin/+ mouse carries a heterozygous germ line mutation in the Apc tumour suppressor gene. The homologous gene is mutated in patients with hereditary colon cancer (FAP, familial adenomatosis polyposis). In the ApcMin/+ mouse, the loss of heterozygosity in Apc allele activates the Wnt/Tcf-pathway which leads to accumulation of β-catenin in the cytosol and its translocation to the cell nucleus. β-Catenin acts as a transcription factor for several genes (e.g. cyclin D1, c-myc) and enhances cell proliferation. ApcMin/+ mice develop dozens of adenomas in the small intestine.

The aim of this study was to investigate the effect of plant stanol feeding on adenoma formation and cell signaling in ApcMin/+ mice. The sterol composition of the intestinal mucosa was also analyzed.

Materials and methods

ApcMin/+ mice were fed either a 0.8% (w/w) plant stanol diet (n=14) or a control diet without plant stanols (n=14). Plant stanols were added to the experimental diet in the form of freeze-dried products with plant stanol ester enrichment. The level of cyclin D1, phosphorylated and total ERK1/2 (extracellular signal regulated kinase) were analyzed from the normal appearing intestinal mucosa by Western blot. Cholesterol, plant sterols (sitosterol, campesterol) and stanols (sitostanol, campestanol) were isolated from the intestinal mucosa by direct saponification method and analyzed by gas chromatography.

Results

The number of small intestinal adenomas was significantly increased by plant stanol feeding (p=0.002). Plant stanols induced adenoma formation by over 60% compared to the control group. No difference in the size of intestinal adenomas was seen. Plant stanol feeding increased the level of activated ERK1 (the ratio of phosphorylated p44 to total p44) and nuclear cyclin D1 in the intestinal mucosa (p=0.024 and p=0.038, respectively). The level of mucosal cholesterol was not affected by plant stanol feeding; however, the level of sitosterol and campesterol were decreased (p&lt;0.001 for both) and sitostanol and campestanol increased (p&lt;0.001 for both) in the intestinal mucosa of plant stanol fed ApcMin/+ mice. The number of intestinal adenomas and the level of mucosal plant sterols appear to have a negative correlation (rs=-0.517; p=0.007).

References

Awad et al. Anticancer Res 1996;16:2797-2804.

Choi et al. Int J Oncol 2003;23:1657-62.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4374.

Berries as chemopreventive dietary constituents--a mechanistic approach with the ApcMin/+ mouse

Berries contain a number of compounds that are proposed to have anticarcinogenic properties. We wanted to see if pure ellagic acid, natural ellagitannins and three wild berries have any effect on the adenoma formation in Apc- mutated Min/+ mice. Min/+ mice were fed high-fat AIN93-G diets containing 10% (w/w) freeze-dried bilberry (Vaccinium myrtillus), lingonberry (Vaccinium vitis-idaea), cloudberry (Rubus chamaemorus), cloudberry seeds or cloudberry pulp or pure ellagic acid at 1564 mg/kg for 10 weeks. beta-Catenin and cyclin D1 protein levels in the adenomas and in the normal-appearing mucosa were determined by Western blotting and immunohistochemistry. Early changes in gene expression in the normal-appearing mucosa were analyzed by Affymetrix microarrays. Three wild berries significantly reduced tumour number (15-30%, p < 0.05), and cloudberry and lingonberry also reduced tumour size by over 60% (p < 0.01). Cloudberry resulted in decreased levels of nuclear beta-catenin and cyclin D1 and lingonberry in the level of cyclin D1 in the large adenomas (p < 0.05). Affymetrix microarrays revealed changes in genes implicated in colon carcinogenesis, including the decreased expression of the adenosine deaminase, ecto-5f-nucleotidase and PGE2 receptor subtype EP4. Ellagic acid had no effect on the number or size of adenomas in the distal or total small intestine but it increased adenoma size in the duodenum when compared with the control diet (p < 0.05). Neither cloudberry seed nor pulp had any effect on the adenoma formation. Berries seem to have great potential as a source of chemopreventive components.

Three Nordic berries inhibit intestinal tumorigenesis in multiple intestinal neoplasia/+ mice by modulating beta-catenin signaling in the tumor and transcription in the mucosa

Berries contain a number of compounds that are proposed to have anticarcinogenic properties. We studied the effects and molecular mechanisms of wild berries with different phenolic profiles on intestinal tumorigenesis in multiple intestinal neoplasia/+ mice. The mice were fed a high-fat AIN93-G diet (Con) or AIN93-G diets containing 10% (w:w) freeze-dried bilberry, lingonberry (LB), or cloudberry (CB) for 10 wk. All 3 berries significantly inhibited the formation of intestinal adenomas as indicated by a 15-30% reduction in tumor number (P < 0.05). CB and LB also reduced tumor burden by over 60% (P < 0.05). Compared to Con, CB and LB resulted in a larger (P < 0.05) proportion of small adenomas (43, 69, and 64%, respectively) and a smaller proportion of large adenomas (56, 29, and 33%, respectively). Beta-catenin and cyclin D1 in the small and large adenomas and in the normal-appearing mucosa were measured by Western blotting and immunohistochemistry. CB resulted in decreased levels of nuclear beta-catenin and cyclin D1 and LB in the level of cyclin D1 in the large adenomas (P < 0.05). Early changes in gene expression in the normal-appearing mucosa were analyzed by Affymetrix microarrays, which revealed changes in genes implicated in colon carcinogenesis, including the decreased expression of the adenosine deaminase, ecto-5'-nucleotidase, and prostaglandin E2 receptor subtype EP4. Our results indicate that berries are potentially a rich source of chemopreventive components.

Effects of a flaxseed mixture and plant oils rich in α-linolenic acid on the adenoma formation in multiple intestinal neoplasia (Min) mice

Flaxseed is a dietary source of possible chemopreventive compounds such as lignans and α-linolenic acid (ALA). To study the effects of a flaxseed mixture on adenoma formation in multiple intestinal neoplasia mice, the mice were fed a diet containing 2·7 % flaxseed, 4·5 % fibre and 3·7 % ALA. To elucidate the effect of oils of the mixture we also composed a diet without flaxseed but with the same oil composition. The median number of adenomas in the small intestine was fifty-four for the control group, and thirty-seven (P=0·023) and forty-two (P=0·095) for flaxseed and oil groups, respectively. Compared with controls (1·2 mm), the adenoma size was smaller in the flaxseed (0·9 mm; P=0·002) and oil (1·0 mm; P=0·012) groups. Both diets changed the proportions of n-3 and n-6 fatty acids in the colonic mucosa. Membrane β-catenin and protein kinase C (PKC)-ζ levels were reduced in the adenoma v. mucosa (P<0·05), and an inverse association was found between the membrane PKC-ζ in the mucosa and the adenoma number (r −0·460, P=0·008, n 32). Only the flaxseed diet increased lignan levels in the caecum (P=0·002) and in plasma (P=0·002) but they were not associated with tumour formation. The results suggest that the preventive effect of flaxseed on colon carcinogenesis may be due to the oil part of flaxseed, and the loss of β-catenin and PKC-ζ from the membranes of the mucosal tissue may play a permissive role in intestinal tumour development.

Nuclear factor kappaB is downregulated and correlates with p53 in the Min mouse mucosa during an accelerated tumor growth

The nuclear factor kappaB signaling pathway has gained attention for its role in the carcinogenic process. We have measured the protein levels of the p65 subunit during a growth of adenomas in the Min mouse model for colon cancer. To study how an accelerated growth of adenomas affect cell signalling, adenoma growth was increased by an inulin diet (10%) that we have shown previously to be a promotor of adenoma formation. In our study, the association between NF-kappaB, p53, beta-catenin, Fas and COX-2 were evaluated by measuring their protein levels in 9- and 15-week old Min mouse adenomas and surrounding mucosa. The amount of p65 rouse between 9- and 15-weeks in the mucosa of the control-fed mice (p = 0.032). The inulin-fed mice had less p65 in the nucleus of the mucosa at 15 weeks of age compared to the control (p = 0.064), although the adenomas were significantly larger (1.46 mm +/- 0.12 for inulin, 0.97 mm +/- 0.12 for control, p < 0.001). Nuclear p65 correlated positively with nuclear p53 in the mucosa (p < 0.001) and adenoma (p < 0.001) tissues. Also, p65 correlated positively with nuclear beta-catenin in the mucosa (p = 0.012) and the adenoma (p = 0.001). Fas expression increased in the inulin group between 9-15 weeks (p = 0.034) and correlated negatively with p65 (p = 0.03). The amount of COX-2 in the adenoma tissue increased between 9-15 weeks and did not correlate with p65. The results suggest that p65 is involved in a p53-dependent apoptotic response in the Min mouse.

Ellagic Acid and Natural Sources of Ellagitannins as Possible Chemopreventive Agents Against Intestinal Tumorigenesis in the Min Mouse

Ellagic acid has been shown to have chemopreventive effects in various experimental cancer models. We wanted to see whether pure ellagic acid and natural ellagitannins from cloudberry (Rubus chamaemorus) seed and pulp have any effect on adenoma formation in Apc-mutated Min mice. From the age of 5 wk, the mice were fed either a control diet, a diet containing pure ellagic acid at 1,564 mg/kg, or diets containing 4.7% (wt/wt) cloudberry seeds or 5.3% cloudberry pulp. The concentrations of ellagitannins and free ellagic acid in the seed diet were 807 and 42 mg/kg and in the pulp diet 820 and 34 mg/kg, respectively. After the 10-wk feeding period, ellagic acid had no effect on the number or size of adenomas in the distal or total small intestine, but it increased adenoma size in the duodenum when compared with the control diet (1.50+/-0.29 vs. 1.16+/-0.31 mm; P=0.029). Neither cloudberry seed nor pulp diets had any effect on the adenoma formation. Chemopreventive effects and mechanisms of whole cloudberry and other similar sources of phenolic compounds should, however, be studied, further taking into account food matrix and interactions with other dietary constituents that may be involved in the bioavailability and metabolism of ellagitannins.

Promotion of adenoma growth by dietary inulin is associated with increase in cyclin D1 and decrease in adhesion proteins in Min/+ mice mucosa

We have earlier shown that dietary fructo-oligosaccharide inulin enhances adenoma growth in multiple intestinal neoplasia (Min/+) mice. To further explore inulin-induced early biochemical changes in the normal-appearing mucosa, Min/+ mice were fed from the age of 5 weeks to the ages of 8 and 15 weeks a control diet or an inulin-enriched diet (10% w/w). In addition, the wild-type littermates were fed with the same diets until the age of 8 weeks, in order to determine whether similar changes happen both in the wild-type and Min/+ mice. The mucosa without adenomas was collected and fractionated to nuclear, cytosolic and membrane pools. The protein levels of beta-catenin, cyclin D1 and E-cadherin were determined by Western blotting at both time points, and immunohistochemical stainings were done for 8-week-old mice. The promotion of adenoma growth by inulin (week 15, 1.3-fold increase, P=.0004) was associated with accumulation of cytosolic and nuclear beta-catenin, and increased amount of cytosolic cyclin D1 (1.5-fold increase, P=.003) in the normal-appearing mucosa of the Min/+ mice. Furthermore, inulin feeding reduced the membranous pools of beta-catenin and E-cadherin. Also in the wild-type mice the drop in membranous beta-catenin was clear (P=.015), and, moreover, a subset of crypts had enhanced nuclear beta-catenin staining. These data indicate that dietary inulin can already activate in the normal-appearing mucosa beta-catenin signaling, which in the presence of Apc mutation induces adenoma growth and even in the wild-type mice direction of the changes is similar.

The plant lignans matairesinol and secoisolariciresinol administered to Min mice do not protect against intestinal tumor formation

The lignans matairesinol (MAT) and secoisolariciresinol (SECO) were fed to Min mice at 0.02% (w/w) in diet to study their effects on intestinal tumor development. The mean number (67 vs. 51, P=0.052) and size (1.4 vs. 1.2 mm, P=0.011) of tumors in the MAT group was elevated when compared with the control group. Tumor formation of the SECO group did not differ from the control group. Intake of MAT increased the level of both MAT and enterolactone in the plasma while SECO feeding increased SECO, enterodiol, and enterolactone (P=0.001). These results showed that MAT or SECO do not prevent intestinal carcinogenesis in Min mice and that MAT may have adverse effects.

Promotion of intestinal tumor formation by inulin is associated with an accumulation of cytosolic beta-catenin in Min mice

Inulin, polydisperse beta (2-1) fructan, has been suggested to protect against colon carcinogenesis and is currently used in a number of food applications. However, the data regarding the role of inulin in intestinal carcinogenesis remains controversial since the results of our previous study suggested that inulin promotes intestinal tumor formation in Min mice, an animal model for intestinal cancer with a mutation in the Apc tumor suppressor gene (Carcinogenesis 2000;21:1167-73). In our present study, we further examined the effects of inulin on intestinal tumor formation in Min mice by carefully analyzing beta-catenin expression and cellular localization at 3 different time points during the tumorigenic process. Min mice were fed a high-fat inulin-enriched (10% w/w) diet or the high-fat diet without any added fiber from the age of 6 weeks to the ages of 9, 12 or 15 weeks. The results showed that inulin significantly increased the number (by 20%) and especially the size (by 44%) of adenomas in the small intestine. At week 15, the promotion of tumor development was accompanied by an accumulation of cytosolic beta-catenin in the adenoma tissue. In the normal appearing mucosa, levels of membrane beta-catenin and PCNA were reduced in the inulin-fed mice, possibly indicating impaired enterocyte migration. These data do not support the earlier suggestions on the cancer preventive effects of inulin and emphasize the need for further research and evaluation where health claims for inulin are concerned.

Diets enriched with cereal brans or inulin modulate protein kinase C activity and isozyme expression in rat colonic mucosa

The role of dietary fibres in colon carcinogenesis is controversial. To elucidate the mechanisms by which different dietary fibre sources may affect colonic tumour development, we studied the effects of diets enriched with cereal brans or inulin on protein kinase C (PKC) activity and isozyme expression in rat colon. Male Wistar rats (twelve per group) were fed one of the following AIN-93G-based diets (Reeves et al. 1993) for 4 weeks: a non-fibre high-fat diet or one of the four high-fat diets supplemented with either rye, oat or wheat bran or inulin at 100 g/kg diet. The fat concentration (20 g/100 g) and fatty acid composition of the non-fibre high-fat diet was designed to approximate that in a typical Western-type diet. In the proximal colon, rats fed the inulin diet had a significantly higher membrane PKC activity and a higher membrane PKC delta level than rats fed the non-fibre diet In the distal colon, rats fed the inulin and oat bran diets had a higher total PKC activity and a higher membrane PKC beta 2 level than rats fed the wheat-bran diet. Rats in the non-fibre and wheat-bran groups had the lowest concentrations of luminal diacylglycerol. In conclusion, feeding of wheat bran resulted in low distal PKC activity and expression of PKC beta 2, a PKC isozyme related to colonic cell proliferation and increased susceptibility for colon carcinogenesis, which may explain in part the protective effect of wheat bran against tumour development in a number of experimental colon cancer studies. The increase in PKC activity and PKC beta 2 expression by feeding inulin may be a drawback of inulin as a functional food.

Chemopreventative activity of crude hydroxymatairesinol (HMR) extract in Apc(Min) mice [corrected]

We studied the effects of a lignan, hydroxymatairesinol (HMR), and rye bran on intestinal tumor development in adenomatous polyposis colimultiple intestinal neoplasia (Apc)(Min) mice. HMR showed a strong chemopreventive effect in this animal model. The mean number of adenomas in the small intestine was significantly lower (26.6+/-11.0, P<0.05) in mice fed the TNS tumor promoter insulin and HMR when compared with the insulin and insulin/rye bran fed mice (39.6+/-8.9 and 36.0+/-7.4, respectively). HMR resulted in normalization of beta-catenin levels in adenoma tissue, indicating that HMR mediates its chemopreventive effect through the Apc-beta-catenin pathway. In the cytosolic fraction, beta-catenin level in adenoma tissue was significantly elevated (P=0.008-0.013) in all the diet groups as compared with that of the surrounding mucosa. In the nuclear fraction, beta-catenin in the insulin (3.15+/-2.9 relative units) and insulin/rye (5.17+/-6.94 relative units) groups was also significantly higher (P=0.003-0.009) in the adenoma tissue when compared with the surrounding mucosa (0.5+/-0.5 and 0.35+/-0.39 relative units). However, HMR was able to restore nuclear beta-catenin level of the adenoma tissue (0.41+/-0.25 relative units) to the level found in the surrounding mucosa (0.36+/-0.28 relative units).

A high-beef diet alters protein kinase C isozyme expression in rat colonic mucosa

We recently reported that a red meat (beef) diet relative to a casein-based diet increases protein kinase C (PKC) activity in rat colonic mucosa. The purpose of this study was to further elucidate the effects of a high-beef diet on colonic intracellular signal transduction by analyzing steady-state protein levels of different PKC isozymes as well as activities of the three types of sphingomyelinases. Male Wistar rats (n = 12/group) were fed AIN93G-based diets either high in beef or casein for 4 weeks. Rats fed the beef diet had significantly (P < 0.05) higher cytosolic PKC alpha and lower membrane PKC delta protein levels than rats fed the casein diet. The beef-fed rats also had alterations in subfractions of PKC zeta/lambda so that they had a significantly (P = 0.001) lower level of membrane 70 & 75 kDa fraction and a higher (P = 0.001) level of cytosolic 40 & 43 kDa fraction than rats fed the casein diet. Because protein levels analyzed with a PKC zeta-specific antibody were similar, these differences in PKC zeta/lambda were probably due to changes in PKC lambda expression. PKC beta2 levels did not differ between the dietary groups. Diet had no significant effect on the activity of acid, neutral, or alkaline sphingomyelinase. This study demonstrated that consumption of a high-beef diet is capable of modulating PKC isozyme levels in rat colon, which might be one of the mechanisms whereby red meat affects colon carcinogenesis.

Beef induces and rye bran prevents the formation of intestinal polyps in Apc(Min) mice: relation to beta-catenin and PKC isozymes

Epidemiological studies suggest that high consumption of red meat and saturated fat and low consumption of fiber are associated with an increased risk of colon cancer. Therefore, we studied whether diets high in red meat or high in different grain fibers as well as inulin, polydisperse beta(2-->1) fructan, could affect the formation of intestinal polyps in Apc(Min) mice. Min mice were fed the following high-fat (40% of energy) diets for 5-6 weeks; a high-beef diet and a casein-based diet without added fiber or casein-based diet with 10% (w/w) oat, rye or wheat bran, or 2.5% (w/w) inulin. One group had a normal low-fat AIN93-G diet. The mice fed the rye-bran diet had the lowest number of polyps in the distal small intestine [15.4 +/- 8.7 (mean +/- SD)], and in the entire intestine (26.4 +/- 12.1). The rye-bran group differed significantly (P = 0. 001-0.004) from the beef group (36.6 +/- 9.4 and 52.8 +/- 13.2). In addition, the beef group differed significantly from the AIN93-G group (P = 0.009) and also from the wheat-bran group (21.0 +/- 6.1 and 35.0 +/- 8.2; P = 0.02) in the distal small intestine. The inulin group (32.9 +/- 14.3 and 49.3 +/- 16.3), on the other hand, was close to the beef group and it differed significantly from the rye-bran group in the distal small intestine. The number of animals bearing tumors in the colon + caecum was only 33% in the rye-bran group when compared with 89% in the beef and 100% in the inulin groups. The mice fed the rye-bran and beef diets had the lowest levels of cytosolic beta-catenin (0.60 +/- 0.42 and 0.67 +/- 0.26) and they differed significantly (P = 0.040 and 0.062) from the mice fed the oat-bran diet (1.46 +/- 0.43). No differences between groups in expression of protein kinase C (PKC) alpha, betaII, delta and zeta were found. The four PKC isozymes were positively correlated with cytosolic beta-catenin levels (r = 0.62-0.68; P < 0.0001).

Phospholipid fatty acid composition and protein kinase C activity in the large intestine of rats fed on butter and coconut-oil diets

Protein kinase C (PKC) has been proposed to play an important role in the aetiology of colon cancer. Therefore, we investigated whether the amount and type of saturated fat could affect colonic PKC activity by modifying either mucosal phospholipid fatty acid composition or faecal diacylglycerol production. Male Wistar rats (n 13 per group) were fed on diets containing butter or coconut oil at energy levels of 10% and 43% for 4 weeks. The control group received a low-fat diet providing 10% of energy from sunflowerseed oil. PKC activity was higher in the distal than the proximal colon but the quantity or type of fat did not alter PKC activity in either region of the colon. Saturated fats caused moderate changes in the fatty acid composition of caecal phospholipids, which were more obvious in the phosphatidylethanolamine than in the phosphatidylcholine fraction. A significant correlation was found between fatty acid composition of phosphatidylcholine and membrane PKC activity. In particular, there was a positive correlation between the proportion of saturated 14:0 and 18:0 and increased PKC activity while unsaturated 18:2n-6, 20:4n-6 and 16:1n-7 were inversely correlated with PKC activity. No relationship was found between phosphatidylethanolamine fatty acids and PKC activity. Concentration of faecal diacylglycerol was not affected by the diet. Overall the data suggest that diets high in saturated fat may not alter colonic PKC activity to a significant extent.