Mieke De Maeyer

Assessment of mycotoxin exposure in the Belgian population using biomarkers: aim, design and methods of the BIOMYCO study

Mycotoxins are harmful food contaminants. Currently, human exposure assessment to these toxins is often based on calculations combining mycotoxin occurrence data in food with population data on food consumption. Because of limitations inherent to that approach, biomarkers have been proposed as a suitable alternative whereby a more accurate assessment of exposure at the individual level can be performed. The BIOMYCO study is designed to assess human mycotoxin exposure using urinary biomarkers of exposure. Over the different seasons of 2013 and 2014, morning urine is gathered in a representative part of the Belgian population according to a designed study protocol, whereby 140 children (3–12 years old) and 278 adults (19–65 years old) are selected based on random cluster sampling stratified for sex, age and geographical areas. Every participant completes a food frequency questionnaire to assess the consumption of relevant foodstuffs (n = 43) of both the day before the urine collection and the previous month. Validated multi-toxin LC-MS/MS methods are used to analyse aflatoxins, fumonisins, ochratoxin A, trichothecenes, zearalenone and their metabolites in morning urine. The study protocol is approved by the ethical committee of the Ghent University Hospital. Within this paper, study design and methods are described. The BIOMYCO study is the first study whereby a multi-toxin approach is applied for mycotoxin exposure assessment in adults and children on a large scale. Moreover, it is the first study that will describe the exposure to an elaborated set of mycotoxins in the Belgian population. In first instance, descriptive analysis will be performed, describing the exposure to mycotoxins for the child and adult group. Exposure of different subgroups will be compared. Furthermore, correlations between the mycotoxin concentrations measured and the food consumption reported will be estimated to explore whether the mycotoxin exposure could be explained by the consumption of certain foods.

Effects of Histidine and β-alanine Supplementation on Human Muscle Carnosine Storage.

Purpose Carnosine is a dipeptide composed of &bgr;-alanine and L-histidine and is present in skeletal muscle. Chronic oral &bgr;-alanine supplementation can induce muscle carnosine loading and is therefore seen as the rate-limiting factor for carnosine synthesis. However, the effect of L-histidine supplementation on carnosine levels in humans is never established. This study aims to investigate whether 1) L-histidine supplementation can induce muscle carnosine loading and 2) combined supplementation of both amino acids is more efficient than &bgr;-alanine supplementation alone. Methods Fifteen male and 15 female participants were equally divided in three groups. Each group was supplemented with either pure &bgr;-alanine (BA) (6 g·d−1), L-histidine (HIS) (3.5 g·d−1), or both amino acids (BA + HIS). Before (D0), after 12 d (D12), and after 23 d (D23) of supplementation, carnosine content was evaluated in soleus and gastrocnemius medialis muscles by 1H-MRS, and venous blood samples were collected. Muscle biopsies were taken at D0 and D23 from the vastus lateralis. Plasma and muscle metabolites (&bgr;-alanine, histidine, and carnosine) were measured by high-performance liquid chromatography. Results Both BA and BA + HIS groups showed increased carnosine concentrations in all investigated muscles, with no difference between these groups. By contrast, carnosine levels in the HIS group remained unaltered. Histidine levels were significantly decreased in plasma (−30.6%) and muscle (−31.6%) of the BA group, and this was prevented when &bgr;-alanine and L-histidine were supplemented simultaneously. Conclusion We confirm that &bgr;-alanine, and not L-histidine, is the rate-limiting precursor for carnosine synthesis in human skeletal muscle. Yet, although L-histidine is not rate limiting, its availability is not unlimited and gradually declines upon chronic &bgr;-alanine supplementation. The significance of this decline still needs to be determined, but may affect physiological processes such as protein synthesis.

Food sources and correlates of sodium and potassium intakes in Flemish pre-school children.

OBJECTIVE The aim of the present study was to investigate dietary sources of Na and K intakes among Flemish pre-school children using multiple linear regression analyses. DESIGN Three-day estimated diet records were used to assess dietary intakes. The contribution to Na and K intakes of fifty-seven food groups was computed by summing the amount provided by the food group for all individuals divided by the total intake for all individuals. SETTING A random cluster sampling design at the level of schools, stratified by province and age, was used. SUBJECTS A representative sample of 696 Flemish pre-school children aged 2·5-6·5 years was recruited. RESULTS Mean Na intake was above and mean K intake was largely below the recommendation for children. Bread (22 %) and soup (13 %) were main contributors to Na intake followed by cold meat cuts and other meat products (12 % and 11 %, respectively). Sugared milk drinks, fried potatoes, milk and fruit juices were the main K sources (13 %, 12 %, 11 % and 11 %, respectively). Although Na and K intakes were positively correlated, several food categories showed Na:K intake ratio well above one (water, cheeses, soup, butter/margarine, fast foods and light beverages) whereas others presented a ratio well below one (oil & fat, fruits & juices, potatoes, vegetables and hot beverages). CONCLUSIONS Flemish pre-school children had too high Na and too low K intakes. The finding that main dietary sources of Na and K are clearly different indicates the feasibility of simultaneously decreasing Na and increasing K intake among children.