Micronutrient intakes and the role of nutritional supplements in the diets of Irish adults and pre-school children

To investigate micronutrient intakes and the role of nutritional supplements in the diets of Irish adults aged 18-64 years and pre-school children aged 1-4 years. Analysis is based on data from the National Adult Nutrition Survey (NANS) (n=1274) and the National Pre-School Nutrition Survey (NPNS) (n=500). Food and beverage intakes and nutritional supplement use were recorded using 4-day food records. Nutrients were estimated using WISP© which is based on McCance and Widdowson’s The Composition of Foods, 6thEd and the Irish Food Composition Database. “Meats”, “milk/yoghurt”, “breads”, “fruit/fruit juices” and “breakfast cereals” made important contributions to the intakes of a number of micronutrients. Micronutrient intakes were generally adequate, with the exception of iron (in adult females and 1 year olds) and vitamin D (in all population groups). For iron, zinc, copper and vitamin B6, up to 2% of adults had intakes that exceeded the upper limit (UL). Small proportions of children had intakes of zinc (11%), copper (2%), retinol (4%) and folic acid (5%) exceeding the UL. Nutritional supplements (predominantly multivitamin and/or mineral preparations) were consumed by 28% of adults and 20% of pre-school children. Among users, supplements were effective in reducing the % with inadequate intakes for vitamins A and D (both population groups) and iron (adult females only). Supplement users had a lower prevalence of inadequate intakes for vitamin A and iron compared to non-users. In adults only, users had a lower prevalence of inadequate intakes for magnesium, calcium and zinc, and displayed better compliance with dietary recommendations and lifestyle characteristics compared with non-users. There is poor compliance among women of childbearing age for the recommendation to take a supplement containing 400µg/day of folic acid. These findings are important for the development of nutrition policies and future recommendations for adults and pre-school children in Ireland and the EU.

Food preservation using antifungal lactic acid bacteria

Fungal spoilage of food and feed prevails as a major problem for the food industry. The use antifungal-producing lactic acid bacteria (LAB) may represent a safer, natural alternative to the use of chemical preservatives in foods. A large scale screen was undertaken to identify a variety of LAB with antifungal properties from plant, animal and human sources. A total of 6,720 LAB colonies were isolated and screened for antifungal activity against the indicator Penicillium expansum. 94 broad-spectrum producers were identified through 16S rRNA sequencing with the majority of the population comprising Lactobacillus plantarum isolates. Six broad-spectrum isolates were consequently characterised. Pedicococcus pentosaceous 54 displayed potent anti-mould capabilities in pear, plum and grape models and may represent an ideal candidate for use in the beverage industry. Two antifungal Lb. plantarum isolates were assessed for their technological robustness and potential as biopreservatives in refrigerated foods. Lb. plantarum 16 and 62 displayed high levels of tolerance to freeze-drying, low temperature exposure and high salt concentrations. Both lactobacilli were introduced as supplements into orange juice to retard the growth of the spoilage yeast Rhodotorula mucilaginosa. Furthermore the isolates were applied as adjuncts in yoghurt production to successfully reduce yeast growth. Lb. plantarum 16 proved to be the optimal inhibitor of yeast growth in both food matrices. To date there is limited information available describing the mechanisms behind fungal inhibition by LAB. The effects of concentrated cell-free supernatant (cCFS), derived from Lb. plantarum 16, on the growth of two food-associated moulds was assessed microscopically. cCFS completely inhibited spore, germ tube and hyphal development. A transcriptomic approach was undertaken to determine the impact of antifungal activity on Aspergillus fumigatus Af293. A variety of genes, most notably those involved in cellular metabolism, were found to have their transcription modulated in response to cCFS which is indicative of global cellular shutdown. This study provides the first insights into the molecular targets of antifungal compounds produced by LAB. The genome sequence of the steep water isolate Lb. plantarum 16 was determined. The complete genome of Lb. plantarum16 consists of a single circular chromosome of 3,044,738 base pairs with an average G+C content of 44.74 % in addition to eight plasmids. The genome represents the smallest of this species to date while harbouring the largest plasmid complement. Some features of particular interest include the presence of two prophages, an interrupted plantaricin cluster and a chromosomal and plasmid encoded polysaccharide cluster. The sequence presented here provides a suitable platform for future studies elucidating the mechanisms governing antifungal production.

Human intestinal microbiota and metabolites they produce in relation to host health

The aim of this thesis was to identify selected potential probiotic characteristics of Bifidobacterium longum strains isolated from human sources, and to examine these characteristics in detail using genomic and phenotypic techniques. One strain in particular Bifidobacterium longum DPC 6315 was the main focus of the thesis and this strain was used in both the manufacture of yoghurt and an animal study. In total, 38 B. longum strains, obtained from infants and adults, were assessed in vitro for the selected probiotic traits using a combined phenotypic and molecular approach. Differentiation of the 38 strains using amplified ribosomal DNA restriction analysis (ARDRA) into subspecies indicated that of the 38 bifidobacterial strains tested, 34 were designated B. longum subsp. longum and four B. longum subsp. infantis.