Biomarkers of food intake for cocoa and liquorice (products): a systematic review

Background

To unravel true links between diet and health, it is important that dietary exposure is accurately measured. Currently, mainly self-reporting methods (e.g. food frequency questionnaires and 24-h recalls) are used to assess food intake in epidemiological studies. However, these traditional instruments are subjective measures and contain well-known biases. Especially, estimating the intake of the group of confectionary products, such as products containing cocoa and liquorice, remains a challenge. The use biomarkers of food intake (BFIs) may provide a more objective measurement. However, an overview of current candidate biomarkers and their validity is missing for both cocoa- and liquorice-containing foods.

Objective

The purpose of the current study was to (1) identify currently described candidate BFIs for cocoa (products) and liquorice, (2) to evaluate the validity of these identified candidate BFIs and (3) to address further validation and/or identification work to be done.

Methods

This systematic review was based on a comprehensive literature search of three databases (PubMed, Scopus and ISI web of Science), to identify candidate BFIs. Via a second search step in the Human Metabolome Database (HMDB), the Food Database (FooDB) and Phenol-Explorer, the specificity of the candidate BFIs was evaluated, followed by an evaluation of the validity of the specific candidate BFIs, via pre-defined criteria.

Results

In total, 37 papers were included for cocoa and 8 papers for liquorice. For cocoa, 164 unique candidate BFIs were obtained, and for liquorice, four were identified in total. Despite the high number of identified BFIs for cocoa, none of the metabolites was specific. Therefore, the validity of these compounds was not further examined. For liquorice intake, 18-glycyrrhetinic acid (18-GA) was found to have the highest assumed validity.

Conclusions

For cocoa, specific BFIs were missing, mainly because the individual BFIs were also found in foods having a similar composition, such as tea (polyphenols) or coffee (caffeine). However, a combination of individual BFIs might lead to discriminating profiles between cocoa (products) and foods with a similar composition. Therefore, studies directly comparing the consumption of cocoa to these similar products are needed, enabling efforts to find a unique profile per product. For liquorice, we identified 18-GA as a promising BFI; however, important information on its validity is missing; thus, more research is necessary. Our findings indicate a need for more studies to determine acceptable BFIs for both cocoa and liquorice.

     

Dietary calcium utilization among a group of spanish boys aged 11–14 years on their usual diets

Adolescence constitutes a period of nutritional vulnerability due to increased dietary requirements for growth and development and special dietary habits. A pilot trial was performed to evaluate the dietary calcium utilization among a sample of Spanish boys on their usual diets, in which the calcium intake and consumption of dairy products were as well examined. Nutrient and food intake was recorded using a 24-h dietary recall and a 2-d food consumption record for 21 subjects aged 11-14 years. Dietary calcium utilization was assessed by means of calcium intake in food and calcium output in faeces and urine as measured by flame atomic absorption spectrophotometry. Overall intake of dairy products was 399.3 +/- 22.1 g/d, and the single most consumed item was milk (72% of the total). An inverse relationship was found between dairy product consumption at breakfast (55% of the total) and BMI (p = 0.016, r = -0.5168). Dairy products contributed the majority of dietary calcium (66.9%). Mean calcium intake was 881.7 +/- 39.9 mg/d, 88% of the recommended value for Spanish adolescents. Net calcium absorption (271.7 +/- 51.7 mg/d) and retention (170.6 +/- 50.9 mg/d) seemed not to be sufficient to meet growth demands during puberty. The results shown that adolescents of the study absorbed 31% of dietary calcium and retained nearly 20% of the total intake, but dietary calcium intake and consumption of dairy products failed to meet recommended values. Optimizing calcium intake is of crucial importance among adolescents, to maximize calcium retention and to help prevent osteoporosis in later life.     

Validation of biomarkers of food intake—critical assessment of candidate biomarkers

Biomarkers of food intake (BFIs) are a promising tool for limiting misclassification in nutrition research where more subjective dietary assessment instruments are used. They may also be used to assess compliance to dietary guidelines or to a dietary intervention. Biomarkers therefore hold promise for direct and objective measurement of food intake. However, the number of comprehensively validated biomarkers of food intake is limited to just a few. Many new candidate biomarkers emerge from metabolic profiling studies and from advances in food chemistry. Furthermore, candidate food intake biomarkers may also be identified based on extensive literature reviews such as described in the guidelines for Biomarker of Food Intake Reviews (BFIRev). To systematically and critically assess the validity of candidate biomarkers of food intake, it is necessary to outline and streamline an optimal and reproducible validation process. A consensus-based procedure was used to provide and evaluate a set of the most important criteria for systematic validation of BFIs. As a result, a validation procedure was developed including eight criteria, plausibility, dose-response, time-response, robustness, reliability, stability, analytical performance, and inter-laboratory reproducibility. The validation has a dual purpose: (1) to estimate the current level of validation of candidate biomarkers of food intake based on an objective and systematic approach and (2) to pinpoint which additional studies are needed to provide full validation of each candidate biomarker of food intake. This position paper on biomarker of food intake validation outlines the second step of the BFIRev procedure but may also be used as such for validation of new candidate biomarkers identified, e.g., in food metabolomic studies.     

Phytoestrogen consumption and association with breast, prostate and colorectal cancer in EPIC Norfolk

Phytoestrogens are polyphenolic secondary plant metabolites that have structural and functional similarities to 17β-oestradiol and have been associated with a protective effect against hormone-related cancers. Most foods in the UK only contain small amounts of phytoestrogens (median content 21 μg/100 g) and the highest content is found in soya and soya-containing foods. The highest phytoestrogen content in commonly consumed foods is found in breads (average content 450 μg/100 g), the main source of isoflavones in the UK diet. The phytoestrogen consumption in cases and controls was considerably lower than in Asian countries. No significant associations between phytoestrogen intake and breast cancer risk in a nested case-control study in EPIC Norfolk were found. Conversely, colorectal cancer risk was inversely associated with enterolignan intake in women but not in men. Prostate cancer risk was positively associated with enterolignan intake, however this association became non-significant when adjusting for dairy intake, suggesting that enterolignans can act as a surrogate marker for dairy or calcium intake.     

Biomarkers of intake for coffee,tea, and sweetened beverages

Non-alcoholic beverages are important sources of nutrients and bioactive compounds that may influence human health and increase or decrease the risk of chronic diseases. A wide variety of beverage constituents are absorbed in the gut, found in the systemic circulation and excreted in urine. They may be used as compliance markers in intervention studies or as biomarkers of intake to improve measurements of beverage consumption in cohort studies and reveal new associations with disease outcomes that may have been overlooked when using dietary questionnaires. Here, biomarkers of intake of some major non-alcoholic beverages—coffee, tea, sugar-sweetened beverages, and low-calorie-sweetened beverages—are reviewed. Results from dietary intervention studies and observational studies are reviewed and analyzed, and respective strengths and weaknesses of the various identified biomarkers discussed. A variety of compounds derived from phenolic acids, alkaloids, and terpenes were shown to be associated with coffee intake and trigonelline and cyclo(isoleucylprolyl) showed a particularly high specificity for coffee intake. Epigallocatechin and 4′-O-methylepigallocatechin appear to be the most sensitive and specific biomarkers for green or black tea, while 4-O-methylgallic acid may be used to assess black tea consumption. Intake of sugar-sweetened beverages has been assessed through the measurement of carbon-13 enrichment of whole blood or of blood alanine in North America where sugar from sugarcane or corn is used as a main ingredient. The most useful biomarkers for low-calorie-sweetened beverages are the low-calorie sweeteners themselves. Further studies are needed to validate these biomarkers in larger and independent populations and to further evaluate their specificity, reproducibility over time, and fields of application.     

Biomarkers of dairy fat intake,incident cardiovascular disease,and all-cause mortality: A cohort study,systematic review,and meta-analysis

BackgroundWe aimed to investigate the association of serum pentadecanoic acid (15:0), a biomarker of dairy fat intake, with incident cardiovascular disease (CVD) and all-cause mortality in a Swedish cohort study. We also systematically reviewed studies of the association of dairy fat biomarkers (circulating or adipose tissue levels of 15:0, heptadecanoic acid [17:0], and trans-palmitoleic acid [t16:1n-7]) with CVD outcomes or all-cause mortality.Methods and findingsWe measured 15:0 in serum cholesterol esters at baseline in 4,150 Swedish adults (51% female, median age 60.5 years). During a median follow-up of 16.6 years, 578 incident CVD events and 676 deaths were identified using Swedish registers. In multivariable-adjusted models, higher 15:0 was associated with lower incident CVD risk in a linear dose–response manner (hazard ratio 0.75 per interquintile range; 95% confidence interval 0.61, 0.93, P = 0.009) and nonlinearly with all-cause mortality (P for nonlinearity = 0.03), with a nadir of mortality risk around median 15:0. In meta-analyses including our Swedish cohort and 17 cohort, case–cohort, or nested case–control studies, higher 15:0 and 17:0 but not t16:1n-7 were inversely associated with total CVD, with the relative risk of highest versus lowest tertile being 0.88 (0.78, 0.99), 0.86 (0.79, 0.93), and 1.01 (0.91, 1.12), respectively. Dairy fat biomarkers were not associated with all-cause mortality in meta-analyses, although there were ≤3 studies for each biomarker. Study limitations include the inability of the biomarkers to distinguish different types of dairy foods and that most studies in the meta-analyses (including our novel cohort study) only assessed biomarkers at baseline, which may increase the risk of misclassification of exposure levels.ConclusionsIn a meta-analysis of 18 observational studies including our new cohort study, higher levels of 15:0 and 17:0 were associated with lower CVD risk. Our findings support the need for clinical and experimental studies to elucidate the causality of these relationships and relevant biological mechanisms.

Kathy Trieu and co-workers study biomarkers of dairy fat intake and associated health outcomes.     

Dietary Silicon Intake of Korean Young Adult Males and Its Relation to their Bone Status

Accumulated data suggests a positive effect of silicon on bone health; however, limited research exists on the silicon content of foods. To further the understanding of the relationship between dietary silicon intake and bone health, a food composition database of commonly consumed foods in Korea is required. For quantitative data on the intake levels of silicon, we analyzed the silicon content of 365 food items commonly consumed in Korea using inductively coupled plasma—atomic emission spectrometry following microwave-assisted digestion. To investigate the dietary silicon intake status and to examine the potential role of dietary silicon intake in the bone status of men, a total of 400 healthy Korean adult males aged 19–25 were observed for their diet intake and calcaneus bone density using the 24-h recall method and quantitative ultrasound, respectively. Clinical markers reflecting bone metabolism such as serum total alkaline phosphatase, N-mid osteocalcin, and type 1 collagen C-terminal telopeptide concentrations were also analyzed. Silicon intake of the subjects was estimated as 37.5 ± 22.2 mg/day. Major food sources of dietary silicon in the Korean male were cereal and cereal products (25.6 % of total silicon intake), vegetables (22.7 %), beverages and liquors (21.2 %), and milk and milk products (7.0 %). Silicon intake correlated positively with age, weight, energy intake, protein intake, calcium intake, and alcohol intake. After adjusted for age, weight, energy intake, protein intake, calcium intake, alcohol intake, smoking cigarettes, and regular exercise status, daily total silicon intake had no correlation with calcaneus bone density and the bone metabolism markers, but silicon intake from vegetables had a positive correlation with serum total alkaline phosphatase activity, a bone formation maker. These findings show the possible positive relationship between dietary silicon intake from vegetables and the bone formation of young adult males. Further investigation in a larger (Korean) population and correcting for additional nutritional confounders is required to confirm these findings.     

Biomarkers of legume intake in human intervention and observational studies: a systematic review

There is a growing interest in assessing dietary intake more accurately across different population groups, and biomarkers have emerged as a complementary tool to replace traditional dietary assessment methods. The purpose of this study was to conduct a systematic review of the literature available and evaluate the applicability and validity of biomarkers of legume intake reported across various observational and intervention studies. A systematic search in PubMed, Scopus, and ISI Web of Knowledge identified 44 studies which met the inclusion criteria for the review. Results from observational studies focused on soy or soy-based foods and demonstrated positive correlations between soy intake and urinary, plasma or serum isoflavonoid levels in different population groups. Similarly, intervention studies demonstrated increased genistein and daidzein levels in urine and plasma following soy intake. Both genistein and daidzein exhibited dose-response relationships. Other isoflavonoid levels such as O-desmethylangolensin (O-DMA) and equol were also reported to increase following soy consumption. Using a developed scoring system, genistein and daidzein can be considered as promising candidate markers for soy consumption. Furthermore, genistein and daidzein also served as good estimates of soy intake as evidenced from long-term exposure studies marking their status as validated biomarkers. On the contrary, only few studies indicated proposed biomarkers for pulses intake, with pipecolic acid and S-methylcysteine reported as markers reflecting dry bean consumption, unsaturated aliphatic, hydroxyl-dicarboxylic acid related to green beans intake and trigonelline reported as marker of peas consumption. However, data regarding criteria such as specificity, dose-response and time-response relationship, reliability, and feasibility to evaluate the validity of these markers is lacking. In conclusion, despite many studies suggesting proposed biomarkers for soy, there is a lack of information on markers of other different subtypes of legumes. Further discovery and validation studies are needed in order to identify reliable biomarkers of legume intake.     

Calcium and Dairy Intake and Measures of Obesity in Hyper‐ and Normocholesterolemic Children

Objective: Calcium intake has been inversely associated with body weight and body fatness in adults and, to a lesser extent, in children. Dairy intake has been inversely associated with metabolic syndrome in overweight but not normal‐weight adults. We assessed whether intakes of calcium and dairy foods were associated with measures of obesity in hypercholesterolemic (HC) and normocholesterolemic (non‐HC) children at baseline and over 1 year. Research Methods and Procedures: Non‐obese 4‐ to 10‐year‐old HC and non‐HC children (342) completed three 24‐hour dietary recalls and provided measures of relative weight (BMI and BMI z scores) and adiposity (sum of skinfolds, trunk skinfolds) at baseline, 3, 6, and 12 months. Cross‐sectional and longitudinal regression analyses, stratified by cholesterol risk status (HC vs. non‐HC) and age (4 to 6 years and 7 to 10 years) and adjusted for potential confounders, were conducted. Results: After adjusting for age, sex, energy intake, and percentage energy from fat, calcium intake was inversely associated with BMI, sum of skinfolds, and trunk skinfolds at baseline and over 1 year in the 7‐ to 10‐year‐old non‐HC children. Results from the regression models also indicated an inverse relation between intake of dairy foods and measures of obesity at baseline in these children. Calcium or dairy intake was not associated with measures of obesity in HC children or in the 4‐ to 6‐year‐old non‐HC children. Discussion: These results suggest a complex relation among intake of calcium and dairy foods, measures of obesity, age, and serum cholesterol in children. Older children without risk of metabolic syndrome may benefit most from increased calcium intake.     

Review: Dairy foods,red meat and processed meat in the diet: implications for health at key life stages

Social and health care provision have led to substantial increases in life expectancy. In the UK this has become higher than 80 years with an even greater proportional increase in those aged 85 years and over. The different life stages give rise to important nutritional challenges and recent reductions in milk consumption have led to sub-optimal intakes of calcium by teenage females in particular when bone growth is at its maximum and of iodine during pregnancy needed to ensure that supply/production of thyroid hormones to the foetus is adequate. Many young and pre-menopausal women have considerably sub-optimal intakes of iron which are likely to be associated with reduced consumption of red meat. A clear concern is the low intakes of calcium especially as a high proportion of the population is of sub-optimal vitamin D status. This may already have had serious consequences in terms of bone development which may not be apparent until later life, particularly in post-menopausal women. This review aims to examine the role of dairy foods and red meat at key life stages in terms of their ability to reduce or increase chronic disease risk. It is clear that milk and dairy foods are key sources of important nutrients such as calcium and iodine and the concentration of some key nutrients, notably iodine can be influenced by the method of primary milk production, in particular, the iodine intake of the dairy cow. Recent meta-analyses show no evidence of increased risk of cardiovascular diseases from high consumption of milk and dairy foods but increasing evidence of a reduction in the risk of type 2 diabetes associated with fermented dairy foods, yoghurt in particular. The recently updated reports from the World Cancer Research Fund International/American Institute for Cancer Research on the associations between dairy foods, red meat and processed meat and various cancers provide further confidence that total dairy products and milk, are associated with a reduced risk of colorectal cancer and high intakes of milk/dairy are not associated with increased risk of breast cancer. Earlier evidence of a significant increase in the risk of colorectal cancer from consumption of red and particularly processed meat has been reinforced by the inclusion of more recent studies. It is essential that nutrition and health-related functionality of foods are included in evaluations of sustainable food production.     

New Biomarkers of Coffee Consumption Identified by the Non-Targeted Metabolomic Profiling of Cohort Study Subjects

Coffee contains various bioactives implicated with human health and disease risk. To accurately assess the effects of overall consumption upon health and disease, individual intake must be measured in large epidemiological studies. Metabolomics has emerged as a powerful approach to discover biomarkers of intake for a large range of foods. Here we report the profiling of the urinary metabolome of cohort study subjects to search for new biomarkers of coffee intake. Using repeated 24-hour dietary records and a food frequency questionnaire, 20 high coffee consumers (183–540 mL/d) and 19 low consumers were selected from the French SU.VI.MAX2 cohort. Morning spot urine samples from each subject were profiled by high-resolution mass spectrometry. Partial least-square discriminant analysis of multidimensional liquid chromatography-mass spectrometry data clearly distinguished high consumers from low via 132 significant (p-value<0.05) discriminating features. Ion clusters whose intensities were most elevated in the high consumers were annotated using online and in-house databases and their identities checked using commercial standards and MS-MS fragmentation. The best discriminants, and thus potential markers of coffee consumption, were the glucuronide of the diterpenoid atractyligenin, the diketopiperazine cyclo(isoleucyl-prolyl), and the alkaloid trigonelline. Some caffeine metabolites, such as 1-methylxanthine, were also among the discriminants, however caffeine may be consumed from other sources and its metabolism is subject to inter-individual variation. Receiver operating characteristics curve analysis showed that the biomarkers identified could be used effectively in combination for increased sensitivity and specificity. Once validated in other cohorts or intervention studies, these specific single or combined biomarkers will become a valuable alternative to assessment of coffee intake by dietary survey and finally lead to a better understanding of the health implications of coffee consumption.     

Vitamin D in foods and as supplements

Numerous studies have shown that the vitamin D status is far from optimal in many countries all over the world. The main reason for this is lack of sunshine. Only a limited number of foods naturally contain vitamin D. Good sources of vitamin D(3) are fish (not only fatty fish), egg yolk, and offal such as liver. Some foods such as milk are fortified with vitamin D in some countries. Dietary vitamin D intake is low in many countries, especially as the dietary sources are limited. The use of supplements is important and seems to be high in some countries. Current dietary intake recommendations are too low to preserve/reach optimal S-25-OHD concentrations, when UVB radiation is not available. We suggest that the recommendations should be increased to at least 10 microg per day in all age groups when solar UVB is scarce. The elderly may need a daily vitamin D intake of 25 microg. If dietary intake of vitamin D is to be increased, food habits will have to change. From a public health point of view it is better to increase the potential sources of vitamin D by fortifying specific products that are consumed commonly in a whole population, or if necessary by especially vulnerable groups. Supplement use is probably the right alternative for vulnerable groups such as infants and inactive elderly in whom this is more easily implemented.     

Inherited Taste Sensitivity to 6‐n‐Propylthiouracil in Diet and Body Weight in Children

Objective: Negative associations between the inherited ability to taste the bitter compound 6‐n‐propylthiouracil (PROP) and preference for fat and body weight have been observed in adults. This study tested the relationships among the ability to taste PROP, reported food intake, and body weight in young children. Research Methods and Procedures: Fifty‐three 4‐ to 5‐year‐old children were classified as tasters (N = 35) or nontasters (N = 18) of PROP using a standard screening solution. Anthropometric measures were taken in the laboratory. Mothers completed questionnaires to assess their child's food intake and their own dieting behaviors. Results: Nontaster boys had higher weight‐for‐height percentiles than taster boys (77th vs. 56th percentile, respectively), but the relationship was opposite for girls (p ≤ 0.05). Nontasters reportedly consumed a higher percentage of their daily energy from protein (p ≤ 0.01), mainly as high‐fat meat products. Tasters reportedly consumed a higher percentage of their daily energy from sugars (p ≤ 0.05), mainly in the form of brownies, doughnuts, cookies, soft drinks, and juice drinks. There were no differences between tasters and nontasters for reported intake of grains, fruits, vegetables, dairy products, or discretionary fats. Discussion: This study is the first, to our knowledge, to report weight differences in children as a function of their PROP status. Genetic taste factors seem to play a role in the development of dietary patterns and weight differences in young children, but the nature of these relationships may vary with gender.     

Factors determining dietary intakes of heterocyclic amines in cooked foods.

The identification of heterocyclic amines (HCAs) in cooked foods has focused attention on the potential health effects from their consumption in the diet. Recent studies have estimated daily dietary intakes of HCAs that vary 10-fold and implicated different cooked meats as the prime source of HCAs in the diet. These varied estimates can be attributed to the different dietary assessment methods used in these studies, as well as the different levels of HCAs ascribed to the most commonly consumed cooked meats. Epidemiological studies utilizing information on dietary practice and food intake have found higher risks for several cancers among individuals consuming the highest levels of HCAs. These studies have highlighted the importance of using information on cooking methods in addition to food intake to accurately estimate dietary exposure to HCAs.     

Non‐replication of genome‐wide‐based associations of efficient food conversion in dairy cows

Animal growth relative to food energy input is of key importance to agricultural production. Several recent studies highlighted genetic markers associated with food conversion efficiency in beef cattle, and there is now a requirement to validate these associations in additional populations and to assess their potential utility for selecting animals with enhanced food‐use efficiency. The current analysis tested a population of dairy cattle using 138 DNA markers previously associated with food intake and growth in a whole‐genome association analysis of beef animals. Although seven markers showed point‐wise significance at P < 0.05, none of the single‐nucleotide polymorphisms tested were significantly associated with food conversion efficiency after correction for multiple testing. These data do not support the involvement of this subset of previously implicated markers in the food conversion efficiency of the physiologically distinct New Zealand Holstein‐Friesian dairy breed.     

Iodine nutrition and breast feeding

A survey of the databanks Medline and Web of science identified studies dealing with maternal and infant iodine nutrition during breast feeding. The iodine concentration of human milk varies widely due to maternal iodine intake. Mean breast milk iodine concentrations are reported as ranging from 5.4 to 2170 μg/L (median 62 μg/L) in worldwide studies. In the few studies that compared length of lactation, gestation length, and parity number, these factors did not significantly affect milk-iodine concentrations. In studies of maternal iodine deficiency, untreated goiter had no impact on breast milk iodine when compared with controls. Iodine in human milk responds quickly to dietary iodine intake, either supplemented or consumed in natural foods. Easily absorbable iodine from foods, supplemental sources, iodine-based medication or iodine-based antiseptic solutions used during parturition, is taken up by the maternal thyroid and mammary glands through the Na⁺/I⁻ symporter system. This transmembrane carrier protein transports iodine against a high concentration gradient. Hormonal iodine in breast milk occurs mainly as T-4, but depending on maternal iodine intake, high concentrations of the inorganic form (iodide) are found. In less developed countries, where natural-food-iodine intake is low, adequate maternal iodine nutritional status depends exclusively on enforcement of food iodination. In industrialized countries, maternal iodine intake has increased as a function of increasing consumption of dairy products. The human infant is sensitive to maternal iodine nutrition during fetal development and later during breast feeding. Environmental factors, not directly related to maternal iodine intake, such as intake of selenium and organochlorine pollutants, can affect thyroid hormone homeostasis in breast-fed infants. In spite of low iodine concentrations found in milk of mothers consuming low-iodine natural foods, long lasting or even life-lasting benefits to the breast-fed infant are demonstrable.     

Tasting novel foods and selecting nutrient content in a highly successful ecological invader,the common myna

Invasion success is dependent on the ability of a species to discover and exploit novel food resources. Within this context, individuals must be willing to taste novel foods. They must also be capable of evaluating the nutritional content of new foods, and selecting their relative intake in order to fulfil their nutritional needs. Whereas the former capacity is well studied, little is known about the latter capacity. First, using the common myna as a model avian invader species, we quantified the willingness of mynas to taste novel foods relative to familiar ones. Mynas readily tasted high protein (HP) novel foods and consumed them in higher quantities compared to a familiar food. Data showed that at three different levels – mixes, ingredients and macronutrients – intake could not be explained by a random model. In experiment 2, we confirmed that mynas were making their selection based on protein (P) content rather than a selection for novelty per se. When given the choice of three equally unfamiliar foods, mynas again ate disproportionately from the high protein relative to high lipid and high carbohydrate foods. Analysis revealed that mynas consumed amounts of protein that were closer to the ones in their natural diet. Finally, in experiment 3, we measured inter‐individual variation in innovation and exploration propensities, and examined associations with inter‐individual variation in consumption of specific macronutrients. This analysis revealed that individuals that selected HP pellets were more exploratory and individuals that selected HC pellets were quicker to solve the innovative foraging task. These findings indicate that not only the willingness to taste novel foods, but also the capacity to evaluate their nutritional content, might be central to the myna's substantial ecological success.     

High Genetic Diversity among Strains of the Unindustrialized Lactic Acid Bacterium Carnobacterium maltaromaticum in Dairy Products as Revealed by Multilocus Sequence Typing

Dairy products are colonized with three main classes of lactic acid bacteria (LAB): opportunistic bacteria, traditional starters, and industrial starters. Most of the population structure studies were previously performed with LAB species belonging to these three classes and give interesting knowledge about the population structure of LAB at the stage where they are already industrialized. However, these studies give little information about the population structure of LAB prior their use as an industrial starter. Carnobacterium maltaromaticum is a LAB colonizing diverse environments, including dairy products. Since this bacterium was discovered relatively recently, it is not yet commercialized as an industrial starter, which makes C. maltaromaticum an interesting model for the study of unindustrialized LAB population structure in dairy products. A multilocus sequence typing scheme based on an analysis of fragments of the genes dapE, ddlA, glpQ, ilvE, pyc, pyrE, and leuS was applied to a collection of 47 strains, including 28 strains isolated from dairy products. The scheme allowed detecting 36 sequence types with a discriminatory index of 0.98. The whole population was clustered in four deeply branched lineages, in which the dairy strains were spread. Moreover, the dairy strains could exhibit a high diversity within these lineages, leading to an overall dairy population with a diversity level as high as that of the nondairy population. These results are in agreement with the hypothesis according to which the industrialization of LAB leads to a diversity reduction in dairy products.     

Immunological biomarkers of tuberculosis

Currently there are no sufficiently validated biomarkers to aid the evaluation of new tuberculosis vaccine candidates, the improvement of tuberculosis diagnostics or the development of more effective and shorter treatment regimens. To date, the detection of Mycobacterium tuberculosis or its products has not been able to adequately address these needs. Understanding the interplay between the host immune system and M. tuberculosis may provide a platform for the identification of suitable biomarkers, through both unbiased and targeted hypothesis-driven approaches. Here, we review immunological markers, their relation to M. tuberculosis infection stages and their potential use in the fight against tuberculosis.     

Circulating fatty acids as biomarkers of dairy fat intake: data from the lifelines biobank and cohort study

Background: C14:0, C15:0, C17:0 and trans-C16:1(n-7) are often used as biomarkers for dairy fat intake. Trans-C18:1(n-7) and CLA, two fatty acids which are also present in dairy, have hardly been explored. We investigated whether trans-C18:1(n-7) and CLA can enrich the existing biomarker portfolio.

Methods: Data were obtained from Lifelines (n?=?769). Dairy fat intake was determined by FFQ. Fatty acids were measured in fasting plasma triglycerides (TG), phospholipids (PL) and cholesterol esters (CE).

Results: Median (25th–75th percentile) intakes of dairy and dairy fat were 322(209–447) and 12.3(8.4–17.4) g/d respectively. A pilot study showed that trans-C18:1(n-7) and CLA were only detectable in TG and PL. Of the established markers, TG C15:0 was most strongly associated with dairy fat intake (standardized β (std.β)?=?0.286, R²?=?0.111). Of the less established markers, TG trans-C18:1(n-7) was most strongly associated with dairy fat intake (Std.β?=?0.292, R²?=?0.115), followed by PL CLA (Std.β?=?0.272, R²?=?0.103) and PL trans-C18:1(n-7) (Std.β?=?0.269, R²?=?0.099). In TG, a combination of C15:0 and trans-C18:1(n-7) performed best (R²?=?0.128). In PL, a combination of C14:0, C15:0, trans-C18:1(n-7) and CLA performed best (R²?=?0.143).

Conclusion: Trans-C18:1(n-7) and CLA can be used as biomarkers of dairy fat intake. Additionally, combining established with less established markers allowed even stronger predictions for dairy fat intake.