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    Carbohydrate-based oil-in-water emulsions for delivery of short-chain fatty acids : Doctor of Philosophy in Food Technology at Riddet Institute, Massey University, Palmerston North, New Zealand
    (Massey University, 2021) Le, Hoang Du
    Short-chain fatty acids (SCFAs) are important functional metabolites. There is clinical evidence to show that they are useful in the prevention of the metabolic syndrome, bowel disorders and certain types of cancer. Therefore, supplementation of SCFAs to the daily diet brings benefits to human health. However, SCFAs are small and water-soluble molecules that are quickly absorbed in the upper gastrointestinal tract. This project aimed to develop carbohydrate-based systems to deliver tripropionin (TP, glycerol tripropionate) and tributyrin (TB, glycerol tributyrate) as sources of propionic and butyric acids into the colon. Two types of emulsion systems were employed, i.e. surfactant-stabilised oil-in-water (O/W) emulsions (single and double-layer systems) and particle-stabilised O/W emulsions (Pickering emulsions). The systems were characterised in terms of structural stability, surface charge, rheological properties, lipolysis degree and release of SCFAs under a static in vitro gastrointestinal digestion and an in vivo study with ileal-cannulated pigs. In the screening experiments, several potential carbohydrate materials were explored, i.e. three modified starches (GUM, N46 and N-LOK), four pectins (PEC) and hydrophobically modified inulin (M-IN), to produce single-layer O/W emulsions. A double-layer O/W emulsion was also produced by combining whey protein isolate (WPI) and chitosan (CS) as the first and second layers, respectively. The capacity of emulsion systems for colon-targeted delivery of SCFAs was then tested using a static in vitro gastrointestinal digestion. The results show that PEC displayed the poorest emulsifying capacity amongst all investigated carbohydrates, leading to an emulsion droplets size (d32) of around 7.3 µm. However, PEC-based formulation was the best system for protection against gastric and intestinal conditions. On the other hand, other single-layer systems and the double-layer system proved to be unstable in the intestinal phase with a significant SCFA release. Deeper investigation on the emulsifying capacity showed that PEC stabilised the O/W emulsion mainly through steric effects. In addition, PEC had the ability to form thick layer around the O/W interface, which was evidenced by confocal laser scanning microscopy and the quantification of adsorbed PEC on the interface. In addition to the above systems, a Pickering O/W emulsion stabilised by hydrophobically modified cellulose nanocrystals (CNCs) was also investigated. The hydrophobic modification of CNCs was carried out, resulting in an increase in static water contact angle from 56o (untreated CNCs) to 80.2o (MCNCs). As a result, the emulsifying capacity of MCNCs was significantly improved. The emulsions prepared from MCNCs ≥ 0.20 wt% were stable against droplet coalescence for up to 4-week storage. In addition, the Pickering emulsions were prone to droplet flocculation at ionic strength ≥ 20 mM NaCl (pH 7.0) or pH < 4.0 (without addition of NaCl), which was due to the charge screening associated with the cellulose molecules at the surface. Similar droplet flocculation was also observed under in vitro gastric conditions, where the emulsions were exposed to low pH and high ionic strength. This gastric-induced structural changes improved physical strength of the emulsions and that enhanced resistance to bile-salt displacement and consequently delayed lipid digestion in the intestinal conditions. In addition, high desorption energy of the MCNC particles at O/W interface of the Pickering emulsion contributed to low lipolysis degree (30–35%). High proportions of SCFAs remaining after the intestinal digestion observed in both PEC and MCNC-based emulsions show a strong promise their use in the colon-targeted delivery of SCFAs. However, CNCs are currently not considered as food-grade materials; therefore, PEC was chosen for the in vivo study using female ileal-cannulated pigs. The in vivo study demonstrated significant higher intestinal lipolysis (~ 51–53%) and lower SCFA release (~ 15%) as compared to the in vitro digestion (~ 40 and 35% respectively). The main reason for the difference between the two models was the absorption of the SCFAs in the pig’s small intestine. However, high proportions of unhydrolysed triglycerides (~ 47–49%) and presence of oil droplets in the ileal-digesta demonstrated successful delivery of SCFAs. Based on the findings in this research, we propose the use of PEC-based emulsion for human trials by incorporating the system into a daily diet or dessert liquid/gel products, such as drinking milk or yogurt. We also believe that the application of MCNC-based Pickering emulsions for colon-target delivery of could be of interest if the regulatory status could be confirmed. The study identifies promising directions for researchers who are interested in improving gut health through delivery of SCFAs to the colon.
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    The role of vitamin D and Omega-3 long chain polyunsaturated fatty acids in children with Autism Spectrum Disorder : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science, Massey University, Albany, New Zealand
    (Massey University, 2018) Mazahery, Hajar
    Background: The efficacy of vitamin D and omega-3 long chain polyunsaturated fatty acid (omega-3 LCPUFA), each individually, in Autism Spectrum Disorder (ASD) has been tested in a few trials and the results are inconclusive. Furthermore, several observational studies have observed low vitamin D and omega-3 LCPUFA status in populations with ASD. Children with ASD are susceptible to nutritional issues and poor diet quality due to sensory, behavioural and gastrointestinal issues associated with the condition, though no information regarding these children’s nutritional status is available in New Zealand. Also, no validated nutritional quality assessment tools are available for this population. Aim and Objectives: The overall aim of this study was to investigate the role of vitamin D (VID), omega-3 LCPUFA (OM), or both (VIDOM) in ASD in children through systematically reviewing literature and conducting an intervention trial with these nutrients. The primary objective was to investigate the efficacy of vitamin D, omega-3 LCPUFA, both on core symptoms and sensory issues after correcting major nutritional deficiencies and secondary objectives were to investigate the efficacy of intervention on irritability and hyperactivity, to study dietary adequacy/nutritional status of children with ASD, and to validate a dietary Index of Children’s Eating (DICE) questionnaire against 4-day estimated food record (4DFR). Methods/Design: New Zealand children with ASD (age 2.5-8.0 years) participated in a 12-month randomised, double-blind, placebo-controlled, 2x2 factorial trial. Prior to trial entry, children’s dietary adequacy and nutritional status were assessed by 4DFR, DICE questionnaire (designed based on New Zealand Ministry of Health Food and Nutrition guidelines), and nutritional biomarkers (25(OH)D, red blood cell fatty acids, iron, calcium, albumin, vitamin B12, and folate). Data regarding dietary supplement use and special/exclusion diet, demographics and anthropometrics (height and weight) were also collected. Children then were randomly assigned to one of four treatment groups; daily 2000IU vitamin D3, 722 mg docosahexaenoic acid (DHA), both supplements, or placebo, and behaviours were assessed. Core symptoms were assessed using Social Responsiveness Scale (SRS), sensory issues using Sensory Processing Measure (SPM), problem behaviours including irritability and hyperactivity using Aberrant Behaviour Checklist (ABC). Outcome measures were analysed pre- and post-intervention. Pair-wise mixed effects longitudinal models were used for data analysis. Results: 309 families registered their interest in the study, of whom 190 families were either excluded or not enrolled. The children of remaining families (n=119) were screened for nutritional deficiencies and high serum 25(OH)D concentrations, of whom two children were excluded. Overall, 62% (73/117) of children completed the trial (placebo 16, VID 19, OM 23, VIDOM 15). The mean serum 25(OH)D concentrations (nmol/L) increased in the VID (27±14, P<0.001) and VIDOM (36±17, P<0.001) groups and changed slightly in the OM (1.1±14, P>0.05) and placebo (8.9±23, P>0.05) groups. The median omega-3 index (%) increased in the OM [4.4 (3.3, 5.9), P<0.001] and VIDOM [4.0 (2.0, 6.0), P<0.001] groups and decreased in the VID [-0.2 (-1.0, 0.1)] and placebo [-0.5 (-0.9, -0.1), P>0.05] groups. Compared to placebo, a greater improvement in multiple outcomes in the intervention groups was observed: SRS-social awareness for OM (0.4±2.9 vs. -1.4±2.3, P=0.03) and VIDOM (0.4±2.9 vs. -1.7±3.5, P=0.03); SRS-social communicative functioning for VIDOM (-5.6±10 vs. -16±24, P=0.07); SRS-total for OM (-5.8±12 vs. -17±18, P=0.08); SPM-taste and smell for VIDOM (-0.3±1.7 vs. -2.5±4.3, P=0.06), SPM-balance and motion for OM (-0.1±4.7 vs. -2.6±4.3, P=0.09), ABC-irritability for VID (0.8±6.1 vs. -4.0±4.9 P=0.01) and OM (0.8±6.1 vs. -5.0±5.0, P=0.001); and ABC-hyperactivity for VID (-0.8±5.6 vs. -5.2±6.3, P=0.047). Out of 86 children whose food records were available, approximately 50% (39/86) reported taking dietary supplements and 15% (13/86) were on a special/exclusion diet. A large proportion of children had dietary intake for vitamin D below the Adequate Intake (AI, 96%), protein below the Average Macronutrient Distribution Range (AMDR, 65%), and iodine below the Estimated Average Requirement (EAR, 54%). Dietary intake of fibre (43%) and vitamin E (37%) was also below the AI by at least one third of children. All or most children exceeded the recommendations for sodium (100%), total saturated fat (80%) and sugar (52%). There was a significant and positive correlation (r=0.7; P<0.001) and good agreement (ĸ=0.6) between total scores from DICE (64±16) and 4DFR (58±11). Participants in the highest tertile of DICE had higher intakes of magnesium (P=0.02), vitamin A (P=0.03) and fibre (P=0.06). Conclusions: Vitamin D and omega-3 LCPUFA, each individually or together, improved some behavioural symptoms of ASD. However, large attrition rates and resultant loss of statistical power preclude definitive conclusion and warrant further trials. Also, the baseline assessment of nutrition confirms nutritional issues and poor diet quality in children with ASD. Given the importance of nutrition in growth and development and in the management of ASD, screening of the nutritional status of children with ASD for nutrient adequacy to reduce under- or over-consumption of nutrients is recommended. DICE is a valid tool for the assessment of diet quality in children with ASD living in New Zealand.
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    Dietary intakes and food sources of omega-6 and omega-3 polyunsaturated fatty acids in pregnant women living in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Human Nutrition at Massey University, Albany, New Zealand
    (Massey University, 2015) Eickstaedt, Michele
    Background/Aims: Adequate intakes of omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFAs) are required for fetal growth, brain development and to support a healthy pregnancy. This study aimed to investigate dietary intakes and food sources of n-6 and n-3 PUFAs in a cohort of New Zealand (NZ) pregnant women. Method: Pregnant women (n=596) in their third trimester of pregnancy from throughout NZ completed an online validated FFQ to assess PUFA intakes over the past three months. Individual and combined intakes of the main PUFAs (linoleic acid, LA; alpha linolenic acid, ALA; arachidonic acid, AA; eicosapentaenoic acid, EPA; docosahexaenoic acid, DHA) were compared with dietary recommendations using frequency summary statistics. Results: Estimated median [25th, 75th percentile] intakes were: 11,580 [8,840, 15,760]mg/d LA (recommended 10,000mg/d), 1,300 [790, 2,120]mg/d ALA (recommended 1,000mg/d), 90 [60, 110]mg/d AA (upper limit 800mg/d), 180 [90, 460]mg/d total n-3 LC-PUFA (EPA plus DHA) (recommended 500mg/d), 60 [30, 190]mg/d EPA (recommended 220mg/d, and 110 [50, 250]mg/d DHA (recommended 200mg/d), with 30.9% of participants consuming more than 200mg/d DHA. Participants taking PUFA supplements (19.6%) had median intakes of 370 [210, 530]mg/d DHA, with 79.5% meeting DHA recommendations. Participants taking PUFA supplements were 16.5 times more likely to meet recommendations for DHA compared to participants not taking supplements. For participants not taking PUFA supplements (80.4%), DHA intakes were 90 [50, 160]mg/d and only 19% met the recommendations. Across all women fish and seafood were the main contributors of DHA (84.8%) and EPA (82.1%) intakes, yet only 9.5% and 12.2% of women consumed canned fish or fresh/frozen fish respectively at least twice per week. Over half of participants reported intakes of poultry (63.1%) and beef (60.8%) at least twice per week. Red meats and poultry (36.8%) alongside eggs (23.3%) were important sources of AA intakes. Fats and oils largely contributed to LA (43.2%) and ALA (55.7%) intakes. Conclusion: The majority of pregnant women did not meet the recommended intakes for DHA, which may be in part due to low fish/seafood intakes. Women taking PUFA supplements were more likely to meet these recommendations. These findings highlight the need for nutrition advice on the benefits of consuming n-3 LC-PUFA rich foods such as fish/seafood during pregnancy.