Milk and dairy products in cancer prevention: focus on bovine lactoferrin

Assessment of the Conformation Stability and Glycosylation Heterogeneity of Lactoferrin by Native Mass Spectrometry

Lactoferrin (LTF) has diverse biological activities and is widely used in functional foods and active additives. Nevertheless, evaluating the proteoform heterogeneity, conformational stability, and activity of LTF remains challenging during its production and storage processes. In this study, we describe the implementation of native mass spectrometry (nMS), glycoproteomics, and an antimicrobial activity assay to assess the quality of LTF. We systematically characterize the purity, glycosylation heterogeneity, conformation, and thermal stability of LTF samples from different sources and transient high-temperature treatments by using nMS and glycoproteomics. Meanwhile, the nMS peak intensity and antimicrobial activity of LTF samples after heat treatment decreased significantly, and the two values were positively correlated. The nMS results provide essential molecular insights into the conformational stability and glycosylation heterogeneity of different LTF samples. Our results underscore the great potential of nMS for LTF quality control and activity evaluation in industrial production.

Whey proteins as multifunctional food materials: Recent advancements in hydrolysis, separation, and peptidomimetic approaches

Whey protein derived bioactives, including α-lactalbumin, ß-lactoglobulin, bovine serum albumin, lactoferrin, transferrin, and proteose-peptones, have exhibited wide ranges of functional, biological and therapeutic properties varying from anticancer, antihypertensive, and antimicrobial effects. In addition, their functional properties involve gelling, emulsifying, and foaming abilities. For these reasons, this review article is framed to understand the relationship existed in between those compound levels and structures with their main functional, biological, and therapeutic properties exhibited either in vitro or in vivo. The impacts of hydrolysis mechanism and separation techniques in enhancing those properties are likewise discussed. Furthermore, special emphasize is given to multifunctional effects of whey derived bioactives and their future trends in ameliorating further food, pharmaceutical, and nutraceutical products. The underlying mechanism effects of those properties are still remained unclear in terms of activity levels, efficacy, and targeted effectiveness. For these reasons, some important models linking to functional properties, thermal properties and cell circumstances are established. Moreover, the coexistence of radical trapping groups, chelating groups, sulfhydryl groups, inhibitory groups, and peptide bonds seemed to be the key elements in triggering those functions and properties. Practical Application: Whey proteins are the byproducts of cheese processing and usually the exploitation of these food waste products has increasingly getting acceptance in many countries, especially European countries. Whey proteins share comparable nutritive values to milk products, particularly on their richness on important proteins that can serve immune protection, structural, and energetic roles. The nutritive profile of whey proteins shows diverse type of bioactive molecules like α-lactalbumin, ß-lactoglobulin, lactoferrin, transferrin, immunoglobulin, and proteose peptones with wide biological importance to the living system, such as in maintaining immunological, neuronal, and signaling roles. The diversification of proteins of whey products prompted scientists to exploit the real mechanisms behind of their biological and therapeutic effects, especially in declining the risk of cancer, tumor, and further complications like diabetes type 2 and hypertension risk effects. For these reasons, profiling these types of proteins using different proteomic and peptidomic approaches helps in determining their biological and therapeutic targets along with their release into gastrointestinal tract conditions and their bioavailabilities into portal circulation, tissue, and organs. The wide applicability of those protein fractions and their derivative bioactive products showed significant impacts in the field of emulsion and double emulsion stabilization by playing roles as emulsifying, surfactant, stabilizing, and foaming agents. Their amphoteric properties helped them to act as excellent encapsulating agents, particularly as vehicle for delivering important vitamins and bioactive compounds. The presence of ferric elements increased their transportation to several metal-ions in the same time increased their scavenging effects to metal-transition and peroxidation of lipids. Their richness with almost essential and nonessential amino acids makes them as selective microbial starters, in addition their richness in sulfhydryl amino acids allowed them to act a cross-linker in conjugating further biomolecules. For instance, conjugating gold-nanoparticles and fluorescent materials in targeting diseases like cancer and tumors in vivo is considered the cutting-edges strategies for these versatile molecules due to their active diffusion across-cell membrane and the presence of specific transporters to these therapeutic molecules.

Molecular characterization and association of lactoferrin gene to subclinical mastitis in goats (Capra hircus)

The study characterized the lactoferrin (Lf) mRNA gene in different goat breeds in the Philippines and determined its association with subclinical mastitis (SCM). The study involved collection of milk at second week of lactation (n=75) and blood samples (n=5) to obtain extracted RNA and using cDNA to amplify Lf gene through polymerase chain reaction. The nucleotide and amino acid sequences were determined and used as reference in the evaluation of phylogenetic relationship. Amplified products were utilized for RFLP analysis before determining the association of the gene with SCM. Results of the study demonstrated that Lf gene in goats registered a molecular weight of 2135. Nucleotide and amino acid sequence of Lf gene revealed high similarity (99%) in Saanen, Anglo-Nubian and Philippine native goats with that of Capra hircus (U53857) Lf gene submitted to GenBank. Phylogenetic studies showed that Lf gene of Anglo-Nubian, Saanen and Native goats clade together with Lf gene of C. hircus (U53857). Three genotypes in goats were documented using the restriction enzymes AluI and HaeIII. Based on the Statistical analysis, association (comp 5.65, p = 0.0308) has been established between the Lf genes of goats with genotype BB to SCM using HaeIII restriction enzyme.

Natural Products: Implication in Cancer Prevention and Treatment through Modulating Various Biological Activities

Cancer is one of the most leading causes of death worldwide. It is one of the primary global diseases that cause morbidity and mortality in millions of people. It is usually caused by different carcinogenic agents that damage the genetic material and alter the cell signaling pathways. Carcinogens are classified into two groups as genotoxic and non-genotoxic agents. Genotoxic carcinogens are capable of directly altering the genetic material, while the non-genotoxic carcinogens are capable of producing cancer by some secondary mechanisms not related to direct gene damage. There is undoubtedly the greatest need to utilize some novel natural products as anticancer agents, as these are within reach everywhere. Interventions by some natural products aimed at decreasing the levels and conditions of these risk factors can reduce the frequency of cancer incidences. Cancer is conventionally treated by surgery, radiation therapy and chemotherapy, but such treatments may be fast-acting and causes adverse effects on normal tissues. Alternative and innovative methods of cancer treatment with the least side effects and improved efficiency are being encouraged. In this review, we discuss the different risk factors of cancer development, conventional and innovative strategies of its management and provide a brief review of the most recognized natural products used as anticancer agents globally.

Lactoferrin CpG Island Hypermethylation and Decoupling of mRNA and Protein Expression in the Early Stages of Prostate Carcinogenesis

Lactoferrin (LTF) is an iron-binding protein canonically known for its innate and adaptive immune functions. LTF may also act as a tumor suppressor with antiproliferative action. LTF is inactivated genetically or epigenetically in various cancers, and a CpG island spanning the transcriptional start site of LTF is hypermethylated in prostate cancer cell lines. We, therefore, hypothesized that LTF expression is silenced via CpG island hypermethylation in the early stages of prostate tumorigenesis carcinogenesis. Targeted methylation analysis was performed using a combination of methylated-DNA precipitation and methylation-sensitive restriction enzymes, and laser-capture microdissection followed by bisulfite sequencing on DNA isolated from prostate tissue samples, including both primary and metastatic disease. LTF mRNA in situ hybridization and LTF protein immunohistochemistry were also performed. We report that the LTF CpG island is frequently and densely methylated in high-grade prostatic intraepithelial neoplasia, primary prostate carcinoma, and metastases. We further report a decoupling of lactoferrin mRNA and protein expression, including in lesions where LTF mRNA has presumably been silenced via CpG island methylation. We conclude that LTF mRNA expression is silenced in prostate tumorigenesis via hypermethylation, supporting a role for LTF as a prostate cancer tumor suppressor gene. Likewise, the frequency at which the LTF CpG island is methylated across samples suggests it is an important and conserved step in prostate cancer initiation.

Investigation and comparison of the anti-tumor activities of lactoferrin, α-lactalbumin, and β-lactoglobulin in A549, HT29, HepG2, and MDA231-LM2 tumor models

To investigate the anti-tumor activities of lactoferrin, α-lactalbumin, and β-lactoglobulin, 4 types of human tumor cells (lung tumor cell A549, intestinal epithelial tumor cell HT29, hepatocellular cell HepG2, and breast cancer cell MDA231-LM2) were exposed to 3 proteins, respectively. The effects on cell proliferation, migration, and apoptosis were detected in vitro, and nude mice bearing tumors were administered the 3 proteins in vivo. Results showed that the 3 proteins (20 g/L) inhibited viability and migration, as well as induced apoptosis, in 4 tumor cells to different degrees (compared with the control). In vivo, tumor weights in the HT29 group (0.84 ± 0.22 g vs. control 2.05 ± 0.49 g) and MDA231-LM2 group (1.11 ± 0.25 g vs. control 2.49 ± 0.57 g) were significantly reduced by lactoferrin; tumor weights in the A549 group (1.07 ± 0.19 g vs. control 3.11 ± 0.73 g) and HepG2 group (2.32 ± 0.46 g vs. control 3.50 ± 0.74 g) were significantly reduced by α-lactalbumin. Moreover, the roles of lactoferrin, α-lactalbumin, and β-lactoglobulin in regulating apoptotic proteins were validated. In summary, lactoferrin, α-lactalbumin, and β-lactoglobulin were proven to inhibit growth and development of A549, HT29, HepG2, and MDA231-LM2 tumors to different degrees via induction of cell apoptosis.

Curd-Peptide Based Novel Hydrogel Inhibits Biofilm Formation, Quorum Sensing, Swimming Mortility of Multi-Antibiotic Resistant Clinical Isolates and Accelerates Wound Healing Activity

The search for a bioactive natural antibacterial agent with wound healing properties is a common practice for the development of new-generation molecules. Antimicrobial peptides are a good alternative to antibiotics and easy-to-form hydrogels under self-assembled conditions without pH adjustment. With this in mind, the peptide pool was extracted from a formulated curd composed of a blend of probiotic bacteria such as Streptococcus thermophilus, Lactobacillus casei, and Bifidobacterium bifidum at an optimized ratio of 7:1:2. The water content of curd was collected by the drainage column, centrifuged, filtered through a 0.45-μM filter, and used for hydrogel preparation. Matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) analysis confirmed the presence of peptide pool in the extracted water. The prepared hydrogel was freeze dried, and its effect on biofilm formation, swarming mortality, antimicrobials, wound healing, and biocompatibility was subsequently verified. Transmission electron microscope (TEM) and scanning electron microscope (SEM) images revealed the fibrous network of peptides after self-assembly with non-polar n-hexane solvent and a porous structure after drying, respectively. The observed biocompatibility, antimicrobial activity, and strong wound healing activity of the developed curd-based hydrogel have opened a new platform for antibacterial ointment formulation.

Independent and joint effects of tea and milk consumption on oral cancer among non-smokers and non-drinkers: a case-control study in China

This study aims to evaluate the independent and joint effects of tea and milk consumption on oral cancer risk among non-smokers and non-drinkers (NS/ND). A hospital-based case-control study was performed in Fujian, China. 421 cases and frequency-matched 1398 controls were included without tobacco smoking and alcohol drinking habits. Unconditional logistic regression model was used to assess the relationship of tea and milk consumption with oral cancer risk. Tea and milk consumption were significantly associated with decreased risk of oral cancer, the adjusted odds ratios (aORs) were 0.73 (95% CI: 0.54-0.97) and 0.69 (95% CI: 0.55-0.88), respectively. According to subgroup analysis, the inverse associations between tea consumption and oral cancer risk were only observed among the elders (>60 years) and urban residents. While the protect effect of milk drinking was more obvious in males, normal body mass index population (18.5–23.9), urban residents and those age ≤ 60 years. Additionally, a significantly multiplicative interaction between tea and milk consumption was observed for oral cancer risk (P = 0.001). The present study is the first to simultaneously assess the association of tea consumption and milk drinking with oral cancer risk. The results suggest that tea and milk consumption are independent protective factors for oral cancer among NS/ND, with a joint effect between them.

Lactoferrin potentially facilitates glucose regulation and enhances the incretin effect

Lactoferrin (Lf) is known for its physiologically pleiotropic properties. In this study, we investigated whether Lf affects glycemic regulation, including glucose absorption from the small intestine. Bovine Lf (bLf, 100 mg/kg body mass) was administered to rats by intraperitoneal injection before intravenous (intravenous glucose tolerance test, IVGTT) or oral glucose administration (oral glucose tolerance test, OGTT). With IVGTT, bLf pretreatment had no significant effect on plasma levels of glucose or insulin. With OGTT, the bLf treatment group tended to show lower plasma levels of glucose than the control group at and after the 15 min peak, and decreased levels of plasma glucose at 180 min. The change in plasma levels of insulin from 0 to 30 min was higher in the bLf treatment group than in the control group. Total plasma glucose-dependent insulinotropic polypeptide (GIP) was lowered at 60 min by the bLf treatment, while an immediate increase in total plasma glucagon-like peptide-1 (GLP-1) was observed within the bLf group undergoing OGTT. In addition, bLf was associated with an increase in the amount of glucose absorbed into the everted jejunum sac. These results suggest that Lf could suppress hyperglycemia, accompanied by elevated plasma levels of insulin via transiently accelerating GLP-1 secretion, and that Lf even enhances glucose absorption from the small intestine.

Lactoferrin ameliorates corticosterone-related acute stress and hyperglycemia in rats

We aimed to assess the effects of lactoferrin (Lf) on glycemic regulatory responses under restraint stress (RS) in rats. Bovine Lf (bLf, 100 mg/kg) was intraperitoneally administered to rats before oral saline administration or oral glucose tolerance test (OGTT) following 60 min of RS load. In the case of oral saline administration, RS significantly raised plasma glucose, but bLf did not affect the level. Plasma glucose in OGTT showed an overall lower transition in the bLf group, and the levels at 30 and 180 min or the area under the curve (AUC) were significantly decreased. Although bLf suppressed an increase in plasma corticosterone during RS, the levels of plasma insulin, epinephrine and glucagon were not changed by the bLf treatment.

Protection Against Dimethylbenz[a] Anthracene-Induced Breast Cancer in Female Rats by α-Lactalbumin

Consumption of α-lactalbumin as dietary protein offers a beneficial effect on breast cancer development. Breast cancer was developed by gavage administration of single dose of dimethylbenz(a)anthracene (DMBA) in female rats, maintained on AIN-76A diet with either 20% casein or α-lactalbumin (a component of whey protein). All tumors were detected by palpation. After approximately 130 days of DMBA administration, the animals were euthanized. There was a delay in the development of breast tumor in the α-lactalbumin group in comparison to the casein group. The number of tumors per rat was less in the α-lactalbumin group than that in the casein group at any time point up to 130 days after DMBA administration. Also the incidence of tumors and tumor volume was less in the α-lactalbumin group than those in the casein group. The casein group had a mixture of grade I, grade II and grade III tumors whereas the α-lactalbumin group had mostly grade I tumor. Furthermore, the proliferative index was significantly lower in the α-lactalbumin group than that in the casein group.

Improving Milk Intake in Milk-Averse Lactose Digesters and Maldigesters

OBJECTIVE

To determine whether a 21-day milk-drinking intervention could reverse milk aversion.

DESIGN

Participants consumed increasing amounts of cow's milk for 21 days. Milk and dairy consumption, aversion, and likeness were assessed pre- and post-intervention and at 3 and 6 months post-intervention.

SETTING

A large Midwestern university.

PARTICIPANTS

Twenty-seven milk-averse individuals completed the intervention, 26 completed the 3-month follow-up, and 24 completed the 6-month follow-up.

MAIN OUTCOMES MEASURED

Participants self-reported milk and dairy consumption, aversion, and degree to which they liked milk.

ANALYSIS

Analysis of variance determined between-subject effects. Independent samples t test determined the effect of time. Fisher exact test determined factors affecting milk consumption.

RESULTS

Lactose digesters and maldigesters showed a significant decrease in overall symptom scores after the milk intervention, with no significant difference between groups. Independent of digestive status, subjects demonstrated a significant decrease in aversion, an increase in the amount to which they liked milk, and an increase in milk and overall calcium consumption at 3 and 6 months post-intervention.

CONCLUSIONS AND IMPLICATIONS

The results suggest a reversal of milk avoidance and the possibility that milk avoiders can increase likeness and incorporate milk into their diet after exposure.

Metabolomics to Explore Impact of Dairy Intake

Dairy products are an important component in the Western diet and represent a valuable source of nutrients for humans. However, a reliable dairy intake assessment in nutrition research is crucial to correctly elucidate the link between dairy intake and human health. Metabolomics is considered a potential tool for assessment of dietary intake instead of traditional methods, such as food frequency questionnaires, food records, and 24-h recalls. Metabolomics has been successfully applied to discriminate between consumption of different dairy products under different experimental conditions. Moreover, potential metabolites related to dairy intake were identified, although these metabolites need to be further validated in other intervention studies before they can be used as valid biomarkers of dairy consumption. Therefore, this review provides an overview of metabolomics for assessment of dairy intake in order to better clarify the role of dairy products in human nutrition and health.

Calcium and vitamin D and risk of colorectal cancer: results from a large population-based case-control study in Newfoundland and Labrador and Ontario

BACKGROUND

Previous epidemiological studies have been suggestive but inconclusive in demonstrating inverse associations of calcium, vitamin D, dairy product intakes with risk of colorectal cancer (CRC). We conducted a large population-based comparison of such associations in Newfoundland and Labrador (NL) and Ontario (ON).

METHODS

A case control study design was used. Colorectal cancer cases were new CRC patients aged 20-74 years. Controls were a sex and age-group matched random sample of the population in each province. 1760 cases and 2481 controls from NL and ON were analyzed. Information on dietary intake and lifestyle was collected using self-administered food frequency and personal history questionnaires.

RESULTS

Controls reported higher mean daily intakes of total calcium and total vitamin D than cases in both provinces. In ON, significant reduced CRC risk was associated with intakes of total calcium (OR of highest vs. lowest quintiles was 0.57, 95% CI 0.42-0.77, p(trend) = 0.03), total vitamin D (OR = 0.73, 95% CI 0.54-1.00), dietary calcium (OR = 0.76, 95% CI 0.60-0.97), dietary vitamin D (OR = 0.77, 95% CI 0.61-0.99), total dairy products and milk (OR = 0.78, 95% CI 0.60-1.00), calcium-containing supplements use (OR = 0.76). In NL, the inverse associations of calcium, vitamin D with CRC risk were most pronounced among calcium- or vitamin D-containing supplement users (OR = 0.67, 0.68, respectively).

CONCLUSIONS

Results of this study add to the evidence that total calcium, dietary calcium, total vitamin D, dietary vitamin D, calcium- or vitamin D-containing supplement use may reduce the risk of CRC. The inverse associations of CRC risk with intakes of total dairy products and milk may be largely due to calcium and vitamin D.

Simultaneous isolation of lactoferrin and lactoperoxidase from bovine colostrum by SPEC 70 SLS cation exchange resin

In this work, simultaneous isolation of lactoferrin (Lf) and lactoperoxidase (Lp) from defatted bovine colostrum by one-step cation exchange chromatography with SPEC 70 SLS ion-exchange resin was investigated. A RP-HPLC method for Lf and Lp determination was developed and optimized as the following conditions: detection wavelength of 220 nm, flow rate of 1 mL/min and acetonitrile concentration from 25% to 75% within 20 min. The adsorption process of Lf on SPEC 70 SLS resin was optimized using Lf standard as substrate. The maximum static binding capacity of SPEC 70 SLS resin was of 22.0 mg/g resin at 15 °C, pH 7.0 and adsorption time 3 h. The Lf adsorption process could be well described by the Langmuir adsorption isotherm model, with a maximum adsorption capacity of 21.73 mg/g resin at 15 °C. In batch fractionation of defatted colostrum, the binding capacities of SPEC 70 SLS resin for adsorbing Lf and Lp simultaneously under the abovementioned conditions were 7.60 and 6.89 mg/g resin, respectively, both of which were superior to those of CM Sepharose F.F. or SP Sepharose F.F. resins under the same conditions. As a result, SPEC 70 SLS resin was considered as a successful candidate for direct and economic purification of Lf and Lp from defatted colostrum.

The effect of bovine milk lactoferrin on human breast cancer cell lines

The evidence that biologically active food components are key environmental factors affecting the incidence of many chronic diseases is overwhelming. However, the full extent of such components in our diet is unknown, as is our understanding of their mechanisms of action. Beyond the interaction of these food components with the gut and intestinal immune functions, whey proteins such as lactoferrin are being tested as anticancer agents. Lactoferrin is an iron-binding protein that has been reported to inhibit several types of cancer. In the present work, the effects of bovine milk lactoferrin on human breast cancer HS578T and T47D cells were studied. The cells were either untreated or treated with lactoferrin concentrations ranging from 0.125 to 125 μM. Lactoferrin decreased the cell viability of HS578T and T47D by 47 and 54%, respectively, and increased apoptosis about 2-fold for both cell lines. Proliferation rates decreased by 40.3 and 63.9% for HS578T and T47D, respectively. For the T47D line, cell migration decreased in the presence of the protein. Although the mechanisms of action are not fully known, the results gathered in this work suggest that lactoferrin interferes with some of the most important steps involved in cancer development.

Calcium intake and associated factors in a general Japanese population: baseline data of NIPPON DATA80/90 and the National Nutrition Survey

Objective

The purpose of this study was to investigate the dietary calcium intake and associated other dietary factors among representative sample of Japanese general men and women.

Methods

Data was obtained by linking NIPPON DATA80 and 90 with the corresponding National Nutrition Surveys held in 1980 and 1990. We analyzed data for 10 422 subjects (4585 men and 5837 women) in NIPPON DATA80 and 8342 subjects (3488 men and 4854 women) in NIPPON DATA90. Calcium intake was calculated by age groups. Dietary calcium intake was classified into quintiles and physical, life-style, and dietary parameters were examined across the quintiles.

Results

For both men and women, calcium intake tended to be positively associated with age in NIPPON DATA80 and 90, and there were significant differences in estimated calcium intake between age groups. Calcium intake tended to be positively associated with age, protein, fat, saturated fat, vitamins A and C, sodium, potassium, and iron for men and women. Calcium intake also tended to be positively associated with intake of nuts, potatoes, sugar and sweeteners, soybeans and legumes, fruits, green and yellow vegetables, other vegetables, mushrooms, sea algae, fish and shellfish, eggs, and milk and dairy products for men and women.

Conclusions

The characteristics of calcium intake in Japanese people were able to be clarified by using the baseline data of NIPPON DATA and the National Nutrition Survey.

Lactoferrin and cancer disease prevention

Lactoferrin (LF) is an iron-binding glycoprotein that is composed of the transferrin family and is predominantly found in the products of the exocrine glands located in the gateways of the digestive, respiratory, and reproductive systems, suggesting a role in the non-specific defence against invading pathogens. Additionally, several physiological roles have been attributed to LF, namely regulation of iron homeostasis, host defence against infection and inflammation, regulation of cellular growth, and differentiation and protection against cancer development and metastasis. These findings have suggested LF's great potential therapeutic use in cancer disease prevention and/or treatment, namely as a chemopreventive agent. This review looks at the recent advances in understanding the mechanisms underlying the multifunctional roles of LF and future perspectives on its potential therapeutic applications.

Intake of dairy products and risk of colorectal neoplasia

Prospective cohort studies suggest that higher intakes of dairy products, in particular milk, are associated with a decreased risk of colorectal cancer (CRC). In Western populations, dairy products are major contributors to dietary Ca, which may have chemopreventive effects in the colon. The pooling of data from prospective studies suggests a significant protective effect of Ca on CRC risk. Randomised controlled trials with Ca supplements have been conducted with both colorectal adenoma and CRC as endpoints. Results suggest that Ca supplementation at a level of 1000-2000 mg/d reduces adenoma recurrence in individuals with a previous adenoma but has no effect on CRC incidence. There is evidence that the risk reduction from dairy foods may not be solely due to their high Ca content. Dairy products contain other potential chemopreventive components such as vitamin D, butyric acid, conjugated linoleic acid, sphingolipids, and probiotic bacteria in fermented products such as yoghurt. The present review will focus on the epidemiological evidence (and in particular prospective cohort studies) investigating the relationship between dairy product consumption and risk of CRC. An outline of the proposed mechanisms responsible for the protective effect of both Ca and other potential chemopreventive components in dairy products will also be presented.

Bovine whey proteins – Overview on their main biological properties

Whey, a liquid by-product, is widely accepted to contain many valuable constituents. These include especially proteins that possess important nutritional and biological properties – particularly with regard to promotion of health, as well as prevention of diseases and health conditions. Antimicrobial and antiviral actions, immune system stimulation, anticarcinogenic activity and other metabolic features have indeed been associated with such whey proteins, as α-lactalbumin, β-lactoglobulin, lactoferrin, lactoperoxidase, and bovine serum albumin. The most important advances reported to date pertaining to biological properties of whey proteins are reviewed in this communication.

Differential effects of dietary whey, casein and soya on colonic DNA damage and large bowel SCFA in rats fed diets low and high in resistant starch

Feeding higher levels of dietary animal protein (as casein or red meat) increases colonic DNA damage and thins the colonic mucus barrier in rats. Feeding resistant starch (RS) reverses these changes and increases large bowel SCFA. The present study examined whether high dietary dairy (casein or whey) or plant (soya) proteins had similar adverse effects and whether dietary RS was protective. Adult male rats were fed diets containing 15 or 25 % casein, whey or soya protein with or without 48 % high amylose starch (as a source of RS) for 4 weeks. DNA damage was measured in isolated colonocytes using the comet assay. Higher dietary casein and soya (but not whey) increased colonocyte DNA damage. DNA damage was highest with soya when fed at 15 or 25 % protein without RS. Dietary RS attenuated protein-induced colonocyte DNA damage in all groups but it remained significantly higher in rats fed 25 % soya compared with those fed 15 % protein. Dietary protein level did not affect colonic mucus thickness overall but the barrier was thinner in rats fed high dietary casein. This effect was reversed by feeding RS. Caecal total SCFA and butyrate pools were higher in rats fed RS compared with digestible starch. Caecal and faecal SCFA were unrelated to genetic damage but correlated with mucus thickness. The present data confirm that higher dietary protein affected colonocyte DNA and colonic mucus thickness adversely but that proteins differ in their effects on these indices of colon health. The data show also that these changes were reversed by RS.

Calcium and dairy food intakes are inversely associated with colorectal cancer risk in the Cohort of Swedish Men

BACKGROUND

Recent epidemiologic studies have generally reported a modest inverse association between calcium intake and the risk of colorectal cancer. However, findings pertaining to specific subsites in the colorectum have been conflicting.

OBJECTIVE

Our objective was to prospectively examine the relations between intakes of calcium and dairy foods and the risk of colorectal cancer, overall and by anatomic subsite, in men from the Cohort of Swedish Men.

DESIGN

In 1997, 45 306 men aged 45-79 y and without a history of cancer completed a food-frequency questionnaire. The men were followed through 31 December 2004.

RESULTS

During a mean follow-up of 6.7 y, we ascertained 449 incident cases of colorectal cancer. After adjustment for age and other known or potential risk factors, the multivariate rate ratio (RR) of colorectal cancer for men in the highest quartile of total calcium intake compared with those in the lowest quartile was 0.68 (95% CI: 0.51, 0.91; P for trend = 0.01). A high consumption of dairy foods was also associated with a lower risk of colorectal cancer. The multivariate RR of colorectal cancer for > or = 7 servings/d of total dairy foods compared with <2 servings/d was 0.46 (0.30, 0.71; P for trend = 0.01). For cancer subsites, the corresponding RRs were 0.37 (0.16, 0.88) for proximal colon, 0.43 (0.20, 0.93) for distal colon, and 0.48 (0.23, 0.99) for rectum.

CONCLUSION

Our findings provide support for inverse associations between intakes of calcium and dairy foods and the risk of colorectal cancer.

Dietary whey protein lowers serum C-peptide concentration and duodenal SREBP-1c mRNA abundance, and reduces occurrence of duodenal tumors and colon aberrant crypt foci in azoxymethane-treated male rats

We evaluated partially hydrolyzed whey protein (WPH) for inhibitory effects on the development of colon aberrant crypt foci (ACF) and intestinal tumors in azoxymethane (AOM)-treated rats. Pregnant Sprague-Dawley rats and their progeny were fed AIN-93G diets containing casein (CAS, control diet) or WPH as the sole protein source. Colons and small intestines from the male progeny were obtained at 6, 12, 20 and 23 weeks after AOM treatment. At 6 and 23 weeks, post-AOM, WPH-fed rats had fewer ACF than did CAS-fed rats. Intestinal tumors were most frequent at 23 weeks, post-AOM. At this time point, differences in colon tumor incidence with diet were not observed; however, WPH-fed rats had fewer tumors in the small intestine (7.6% vs. 26% incidence, P=.004). Partially hydrolized whey protein suppressed circulating C-peptide concentration (a stable indicator of steady-state insulin secretion) at all four time points relative to the corresponding CAS-fed animals. The relative mRNA abundance for the insulin-responsive, transcription factor gene, SREBP-1c, was reduced by WPH in the duodenum but not colon. Results indicate potential physiological linkages of dietary protein type with circulating C-peptide (and by inference insulin), local expression of SREBP-1c gene and propensity for small intestine tumorigenesis.

Focused interviews with Sudanese Americans: perceptions about diet, nutrition, and cancer

BACKGROUND

This study explored perceptions regarding diet, nutrition and cancer among Sudanese-Americans; and generated information for response options, components to questions, and actual questions for a pre-conceptualized diet, nutrition and cancer-related questionnaire to be used on this population.

METHODS

In a descriptive, qualitative study, data were collected from four focus group discussions with Sudanese-Americans (N = 18).

RESULTS

Most participants were fearful of cancer, associating it with death. Stress, genetics, and pesticides in vegetables were given as major causes of cancer. Fatalism towards cancer pervaded among a few participants. Male participants did not believe that dietary factors could be helpful in cancer prevention, while the females believed fried, fatty, smoked and fast foods could lead to cancer. Factors perceived as influencing food choices included money, cultural traditions and social class. Cultural tradition was perceived as the major barrier to changing food habits. Frying, stewing, grilling, boiling and fermenting were the most common food preparation methods reported.

CONCLUSION

Perceptions regarding dietary practices, nutrition and cancer among Sudanese-Americans, some of which might have been overlooked were identified. The focus groups generated response options, components to questions, and actual questions for a pre-conceptualized diet, nutrition and cancer-related questionnaire to be used on Sudanese-Americans.

Expression and prognostic value of lactoferrin mRNA isoforms in human breast cancer

We investigated the expression levels of human lactoferrin (Lf), a steroid hormone-inducible gene product the expression of which is often altered during oncogenesis, and of Delta-lactoferrin (DeltaLf), its alternative isoform, which has been shown to be absent from tumor cell lines in commonly used human breast epithelial cell lines, using semiquantitative RT-PCR. Both mRNAs were detected but with levels of expression lower than those found in normal breast epithelial cells. This downregulation was much more visible for DeltaLf since its expression was either significantly diminished (BT-20, MCF-7 cell lines) or practically absent (MDA-MB-231, T-47D, HBL 100 cell lines). In order to determine whether Lf gene products are useful prognosic tools, we further analyzed their expression levels in 99 primary breast cancer biopsies. DeltaLf transcripts were found in all of the samples, whereas Lf transcripts were found in 88% of them. Lf and DeltaLf expression levels were positively correlated (p = 0.003). Lf expression was related to tumor type with a higher recovery in lobular-type tumors (p = 0.04). DeltaLf expression was related to the histoprognostic grading (p = 0.02). In univariate analyses, DeltaLf and Lf expressions were prognosis parameters, high concentrations being associated with a longer overall survival.

Cancer prevention by natural compounds

Increasing attention is being paid to the possibility of applying cancer chemopreventive agents for individuals at high risk of neoplastic development. For this purpose by natural compounds have practical advantages with regard to availability, suitability for oral application, regulatory approval and mechanisms of action. Candidate substances such as phytochemicals present in foods and their derivatives have been identified by a combination of epidemiological and experimental studies. Plant constituents include vitamin derivatives, phenolic and flavonoid agents, organic sulfur compounds, isothiocyanates, curcumins, fatty acids and d-limonene. Examples of compounds from animals are unsaturated fatty acids and lactoferrin. Recent studies have indicated that mechanisms underlying chemopreventive potential may be combinations of anti-oxidant, anti-inflammatory, immune-enhancing, and anti-hormone effects, with modification of drug-metabolizing enzymes, influence on the cell cycle and cell differentiation, induction of apoptosis and suppression of proliferation and angiogenesis playing roles in the initiation and secondary modification stages of neoplastic development. Accordingly, natural agents are advantageous for application to humans because of their combined mild mechanism. Here we review naturally occurring compounds useful for cancer chemprevention based on in vivo studies with reference to their structures, sources and mechanisms of action.

Arachidonic acid and colorectal carcinogenesis

Colorectal carcinoma is a leading cause of cancer related death worldwide. This deadly disease advances through a series of clinical and histopathological stages, initiated by single crypt lesions to small benign tumors and finally to malignancy. Although some progress has been made in elucidating the formation of colorectal tumors at molecular/genetic levels, the possible mechanisms of dietary lipids in inducing and promoting colorectal tumorigenesis are poorly understood. Recent epidemiological studies, however, indicate that lipid-rich diet containing omega-6 fatty acids (i.e. linoleic acid, arachidonic acid, etc.) may somehow be related with the disease process. Rapid metabolism of arachidonic acid, increased activities of phospholipases (i.e. phospholipase-A2s), and the elevated levels of cyclooxygenase (COX) and lipoxygenase (LOX) in colonic cells were reported in various stages of the malignancy, suggesting a possible link between dietary lipids and the incidence of colorectal cancer. The major focus of this review is to delineate the recent findings on enhanced arachidonic acid metabolism and its conversion into eicosanoids during the initiation and progression of colorectal carcinogenesis. In addition, the identification and participation of various phospholipases are also discussed. It is speculated that many of these phospholipases can be used as targets for developing new drugs against colorectal as well as other adenocarcinomas.

Arachidonic acid and colorectal carcinogenesis

Colorectal carcinoma is a leading cause of cancer related death worldwide. This deadly disease advances through a series of clinical and histopathological stages, initiated by single crypt lesions to small benign tumors and finally to malignancy. Although some progress has been made in elucidating the formation of colorectal tumors at molecular/genetic levels, the possible mechanisms of dietary lipids in inducing and promoting colorectal tumorigenesis are poorly understood. Recent epidemiological studies, however, indicate that lipid-rich diet containing omega-6 fatty acids (i.e. linoleic acid, arachidonic acid, etc.) may somehow be related with the disease process. Rapid metabolism of arachidonic acid, increased activities of phospholipases (i.e. phospholipase-A2s), and the elevated levels of cyclooxygenase (COX) and lipoxygenase (LOX) in colonic cells were reported in various stages of the malignancy, suggesting a possible link between dietary lipids and the incidence of colorectal cancer. The major focus of this review is to delineate the recent findings on enhanced arachidonic acid metabolism and its conversion into eicosanoids during the initiation and progression of colorectal carcinogenesis. In addition, the identification and participation of various phospholipases are also discussed. It is speculated that many of these phospholipases can be used as targets for developing new drugs against colorectal as well as other adenocarcinomas.

Dairy Foods, Calcium, and Colorectal Cancer: A Pooled Analysis of 10 Cohort Studies

BACKGROUND

Studies in animals have suggested that calcium may reduce the risk of colorectal cancer. However, results from epidemiologic studies of intake of calcium or dairy foods and colorectal cancer risk have been inconclusive.

METHODS

We pooled the primary data from 10 cohort studies in five countries that assessed usual dietary intake by using a validated food frequency questionnaire at baseline. For most studies, follow-up was extended beyond that in the original publication. The studies included 534 536 individuals, among whom 4992 incident cases of colorectal cancer were diagnosed between 6 and 16 years of follow-up. Pooled multivariable relative risks for categories of milk intake and quintiles of calcium intake and 95% confidence intervals (CIs) were calculated. All statistical tests were two-sided.

RESULTS

Milk intake was related to a reduced risk of colorectal cancer. Compared with the lowest category of intake (<70 g/day), relative risks of colorectal cancer for increasing categories (70-174, 175-249, and > or =250 g/day) of milk intake were 0.94 (95% CI = 0.86 to 1.02), 0.88 (95% CI = 0.81 to 0.96), and 0.85 (95% CI = 0.78 to 0.94), respectively (P(trend)<.001). Calcium intake was also inversely related to the risk of colorectal cancer. The relative risk for the highest versus the lowest quintile of intake was 0.86 (95% CI = 0.78 to 0.95; P(trend) =.02) for dietary calcium and 0.78 (95% CI = 0.69 to 0.88; P(trend)<.001) for total calcium (combining dietary and supplemental sources). These results were consistent across studies and sex. The inverse association for milk was limited to cancers of the distal colon (P(trend)<.001) and rectum (P(trend) =.02).

CONCLUSION

Higher consumption of milk and calcium is associated with a lower risk of colorectal cancer.

Effect of whey protein isolate on intracellular glutathione and oxidant-induced cell death in human prostate epithelial cells

Cysteine is the rate-limiting amino acid for synthesis of the ubiquitous antioxidant glutathione (GSH). Bovine whey proteins are rich in cystine, the disulfide form of the amino acid cysteine. The objective of this study was to determine whether enzymatically hydrolyzed whey protein isolate (WPI) could increase intracellular GSH concentrations and protect against oxidant-induced cell death in a human prostate epithelial cell line (designated RWPE-1). Treatment of RWPE-1 cells with hydrolyzed WPI (500 microg/ml) significantly increased intracellular GSH by 64%, compared with control cells receiving no hydrolyzed WPI (P<0.05). A similar increase in GSH was observed with N-acetylcysteine (500 microM), a cysteine-donating compound known to elevate intracellular GSH. In contrast, treatment with hydrolyzed sodium caseinate (500 microg/ml), a cystine-poor protein source, did not significantly elevate intracellular GSH. Hydrolyzed WPI (500 microg/ml) significantly protected RWPE-1 cells from oxidant-induced cell death, compared with controls receiving no WPI (P<0.05). The results of this study indicate that WPI can increase GSH synthesis and protect against oxidant-induced cell death in human prostate cells.