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Genetic variation may explain the heterogeneity in the lipid response to dietary change. A systematic literature review found 79 articles on dietary intervention studies, 14 articles on observational studies, and 22 reviews on diet-gene interactions. The evidence suggests that variation within the genes for apolipoprotein (apo) AI, AIV, B and E may influence the lipid response to dietary change. This study assessed the influence of six polymorphisms within the genes for apo B, apo E and lipoprotein lipase (LPL) on the association between habitual diet and lipid levels in 239 healthy men and women (91 men and 148 women) aged 18-54 years, including 110 twin pairs, who were recruited for a population-based study of coronary heart disease (CHD) risk factors. Diet was assessed by a food frequency questionnaire, which was compared with 4-day weighed records in 41 men and 40 women aged 19-58 years. The nutrients of interest had either a correlation coefficient ≥0.5, ≥50/≤10% in the same/opposite third, a KW30.04. Genotypes were determined by the polymerase chain reaction and digestion with the appropriate enzyme. Significant diet-gene interactions were observed at each of the polymorphic sites, suggesting that genetic variation contributes to the framework within which diet, especially n-3 PUFAs, the P:S ratio and NSP can influence lipid levels. In particular, individuals with the apo B XbaI X+ allele, the apo B signal peptide insertion/deletion D allele, the apo &egr;4 allele, the LPL PvuII P- allele and the LPL S447X X allele may be at greater risk of developing CHD due to their poorer lipid profiles and/or poorer response to diet. At present, it is premature to recommend the use of genotyping in the design of therapeutic diets, however investigating diet-gene interactions will increase our knowledge of the mechanisms involved in the role of diet in reducing CHD risk.

Thesis advisor: Thanh V. Tran / Research has established that dietary quality among Asian immigrants declined after immigrating to the United States, indicated by decreasing intake of healthy food and increasing intake of unhealthy food. There is a need for a broader investigation for the interactive influence of acculturation, sociodemographic and environmental factors on dietary intake among this population. Guided by the Operant Theory of Acculturation, and the Dietary Acculturation Theory, the present study examined the following research questions to address the gaps in the literature: (1) Are acculturation factors associated with dietary intake among Asian immigrants? (2) What sociodemographic factors are associated with dietary intake among Asian immigrants? (3) What environmental factors are associated with dietary intake among Asian immigrants? (4) What sociodemographic factors moderate the effect of acculturation on dietary intake among Asian immigrants? (5) What environmental factors moderate the effect of acculturation on dietary intake among Asian immigrants? The data in use come from the 2011 – 2012 Adult California Health Interview survey. The sample includes 2,122 non-Hispanic Asian adults born out of the United States. Results from negative binomial regression indicate that intake of fruits, vegetables, soda, fries and fast food was all negatively associated with living in the United States for at least 10 years, compared to living in the Unites States for less than 10 years. The present study also found sociodemographic (including ethnicity, age, gender, education, employment status, and income) and environmental factors (including family type, household size, household tenure, housing type, perceived availability of fresh fruits and vegetables, residential area category, and participation in food stamp and WIC) statistically significantly confounded and moderated the association between length of time lived in the United States and dietary intake. Findings from this study extend the understanding of the protective and risk factors for Asian immigrants to develop and maintain healthy diet, and demonstrated the complexity of dietary changes among Asian immigrants. Based on the findings, the importance that social work research and practice in addressing nutrition inequality among Asian immigrants was highlighted. The study also discovered potential issues and challenges of developing measurement for dietary intake among Asian immigrants, and provided empirical evidence of longitudinal research designs to further explain dietary changes, and guidelines for community-based interventions to address strategies of nutrition promotion among Asian immigrants. / Thesis (PhD) — Boston College, 2017. / Submitted to: Boston College. Graduate School of Social Work. / Discipline: Social Work.

Viscosity and fermentability are considered important properties of dietary fiber. Viscosity increases digesta viscosity and reduces digesta passage rate, nutrient digestion and absorption whereas fermentability increases fermentation into short chain fatty acids (SCFA). The objectives were to enhance the understanding of these properties of dietary fiber and their effects on digestive physiology using surgical models in pigs. In study 1, three catheterized pigs fed 3 diets containing 0, 3, or 6% oat -glucan concentrate (BG0, BG3, and BG6) in a repeated 3 3 Latin square. Pigs fed BG6 had a lower net glucose flux. Pigs fed BG6 tended to have lower portal C-peptide without lowered insulin. Pigs fed BG6 had lower portal glucose dependent insulinotropic peptide (GIP) and glucagon like peptide-1 (GLP-1), which in turn were correlated (R2 = 0.81 and 0.88, respectively) with portal glucose. Pigs fed BG3 and BG6 had a higher net SCFA flux, indicating increased fermentation. In study 2 and 3, ileal cannulated grower pigs were fed semi-purified diets supplemented with 5% purified non-starch polysaccharides (NSP) in a 2 (low and high viscous) 2 (low, and high fermentable) factorial arrangement using cellulose (CEL), carboxymethylcellulose (CMC), and low and high viscous oat -glucan (LBG and HBG, respectively). The CMC, LBG and HBG induced high ileal digesta viscosity coinciding with high nutrient digestibility; in contrast, CEL had lowest viscosity and nutrient digestibility. The CEL, LBG and HBG increased fecal SCFA. Linear discriminate analysis of NSP and TRFLP profiles and 16S rRNA gene copy numbers of bacterial groups revealed that CMC resulted in distinctive bacterial communities. The gene copy number of butyryl-CoA CoA transferase was higher than for butyrate kinase, indicating that this pathway is dominant for butyrate production in pigs. In study 4, similar dietary treatments were fed to catheterized pigs. High viscous and fermentable HBG increased net butyrate flux and insulin and GLP-1 production but did not affect net glucose flux. Thus, the viscosity and fermentability are important functional properties of dietary fiber that better explained the physiological effects on kinetics of digestion, absorption, hormones responses, fermentation and thus nutrient flow and intestinal health. / Animal Science

Introduction: Prior research has shown that dietary supplement use is a common practice among college students. Most of these studies used surveys and questionnaires to provide an overview of supplement use in the U.S. However, in-depth information on college students’ perceptions and/or concerns related to dietary supplement use is lacking. The aim of this study was to capture a deeper understanding of how college students perceive dietary supplements. Methods: A qualitative case study design was used, which allowed a greater understanding of the case through content analysis. The study used a secondary database, which consisted of web log (blog) posts completed as an assignment in an undergraduate introductory nutrition course. Students were asked to describe their experiences with and beliefs about the use of dietary supplements in a discussion format using a blogging tool. Blog posts were coded and analyzed using QDA Miner computer software. The most commonly mentioned topics were then explored in their original context. Results: Final coding of the blog data revealed four main categories: supplements used, rationale for use, sources of information, and perceptions about the safety of dietary supplements. The most commonly mentioned supplements were multivitamins, diet pills, creatine, and protein supplements. Blog data revealed that a common reason students took dietary supplements was a perceived lack of nutrients in their diet. Information about dietary supplements came mainly from friends’ or family members’ experiences with supplements. Many students had misconceptions about supplements, were not familiar with them, and/or questioned their effectiveness. Conclusions: Based on the study findings, educational programs for college students should focus on common misconceptions; the safety and efficacy of supplements, especially diet pills and protein supplements; critical analysis of supplement information; and the appropriateness of supplement use.

The overall goal of the present research project was to investigate the physiology of dietary iron absorption and its interactions with the uptake and metabolism of other divalent metals, especially cadmium, in freshwater fish, using rainbow trout (Oncorhynchus mykiss) as a model species. Using intestinal sac preparations, iron absorption was found to occur along the entire intestinal tract of fish, with anterior intestine being the major site of absorption compared to either mid or posterior intestine. Ferrous iron was more bioavailable than ferric iron, and the uptake of ferrous iron was significantly reduced at alkaline pH (p < 0.05). These findings suggested that a homolog of the mammalian apical ferrous iron transporter, divalent metal transporter-1 (DMT1, a Fe2+/H+ symporter), is involved in the absorption of iron in the fish intestine. Ferric iron appeared to be absorbed through the same pathway as ferrous iron following reduction by an apical ferric reductase. Several divalent metals, both essential (nickel, copper and zinc) and non-essential (cadmium and lead), inhibited intestinal ferrous iron absorption in fish. Importantly, elevated luminal iron reciprocally reduced the accumulation of cadmium in the fish intestine, indicating the significance of the iron transport pathway in dietary cadmium absorption. Two different DMT1 isoforms, Nramp-â and -ã, were found to be expressed along the entire gastrointestinal tract of fish. My study showed that in isolated rainbow trout enterocytes, ferrous iron uptake occurred through a saturable and proton-dependent process, providing further evidence of DMT1-mediated ferrous iron transport. Both cadmium and lead inhibited ferrous iron uptake in the enterocytes in a concentration-dependent manner. Kinetic characterization revealed that the apparent affinity for ferrous iron uptake is significantly decreased (increased Km) in the presence of either cadmium or lead (p < 0.05), whereas the maximum uptake rate (Jmax) remains unchanged. These results indicated that the interaction between ferrous iron and cadmium or lead is competitive in nature, and the uptake of these metals occurs through a common transport pathway (likely DMT1). The uptake characteristics of cadmium were further examined in isolated rainbow trout enterocytes, and my findings indicated that in addition to DMT1, cadmium uptake can be mediated by zinc transport pathway (ZIP8, a Zn2+/HCO3- symporter). My study also showed that cysteine-conjugated cadmium was readily bioavailable to fish enterocytes, possibly via a cysteine-specific transport pathway. The efflux of cadmium from the enterocytes was found to occur via an ATPase-driven pathway. On the other hand, chronic exposure to dietary cadmium at an environmentally-relevant concentration significantly increased cadmium burden in target organs as well as in the whole-body of fish (p < 0.05). Exposure to dietary cadmium increased the mRNA expression level of key stress-inducible proteins such as metallothioneins (MT-A and MT-B) and heat shock proteins-70 (HSP-70a and HSP-70b). Interestingly, each MT and HSP-70 mRNA isoform responded differently in various target organs of fish following dietary cadmium exposure. Fish exposed to dietary cadmium also exhibited an increase in the hepatic transferrin mRNA level as well as the plasma transferrin protein level, indicating the role of transferrin in cadmium handling in fish. Importantly, an iron-supplemented diet reduced cadmium burden in the gut and the whole-body, and ameliorated the expression of MT and HSP-70 genes in fish. These results suggested the protective effects of elevated dietary iron against chronic dietary cadmium toxicity in fish. Overall, findings from the present research project provided novel and important physiological and molecular insights into the uptake, interactions and homeostasis of dietary divalent metals in freshwater fish. This information greatly enhances our current understanding of the toxicological implications for dietary metal exposure in metal contaminated wild fish populations, and may ultimately help the regulators to develop better strategies for ecological risk assessment of metals.

The overall goal of the present research project was to investigate the physiology of dietary iron absorption and its interactions with the uptake and metabolism of other divalent metals, especially cadmium, in freshwater fish, using rainbow trout (Oncorhynchus mykiss) as a model species. Using intestinal sac preparations, iron absorption was found to occur along the entire intestinal tract of fish, with anterior intestine being the major site of absorption compared to either mid or posterior intestine. Ferrous iron was more bioavailable than ferric iron, and the uptake of ferrous iron was significantly reduced at alkaline pH (p < 0.05). These findings suggested that a homolog of the mammalian apical ferrous iron transporter, divalent metal transporter-1 (DMT1, a Fe2+/H+ symporter), is involved in the absorption of iron in the fish intestine. Ferric iron appeared to be absorbed through the same pathway as ferrous iron following reduction by an apical ferric reductase. Several divalent metals, both essential (nickel, copper and zinc) and non-essential (cadmium and lead), inhibited intestinal ferrous iron absorption in fish. Importantly, elevated luminal iron reciprocally reduced the accumulation of cadmium in the fish intestine, indicating the significance of the iron transport pathway in dietary cadmium absorption. Two different DMT1 isoforms, Nramp-â and -ã, were found to be expressed along the entire gastrointestinal tract of fish. My study showed that in isolated rainbow trout enterocytes, ferrous iron uptake occurred through a saturable and proton-dependent process, providing further evidence of DMT1-mediated ferrous iron transport. Both cadmium and lead inhibited ferrous iron uptake in the enterocytes in a concentration-dependent manner. Kinetic characterization revealed that the apparent affinity for ferrous iron uptake is significantly decreased (increased Km) in the presence of either cadmium or lead (p < 0.05), whereas the maximum uptake rate (Jmax) remains unchanged. These results indicated that the interaction between ferrous iron and cadmium or lead is competitive in nature, and the uptake of these metals occurs through a common transport pathway (likely DMT1). The uptake characteristics of cadmium were further examined in isolated rainbow trout enterocytes, and my findings indicated that in addition to DMT1, cadmium uptake can be mediated by zinc transport pathway (ZIP8, a Zn2+/HCO3- symporter). My study also showed that cysteine-conjugated cadmium was readily bioavailable to fish enterocytes, possibly via a cysteine-specific transport pathway. The efflux of cadmium from the enterocytes was found to occur via an ATPase-driven pathway. On the other hand, chronic exposure to dietary cadmium at an environmentally-relevant concentration significantly increased cadmium burden in target organs as well as in the whole-body of fish (p < 0.05). Exposure to dietary cadmium increased the mRNA expression level of key stress-inducible proteins such as metallothioneins (MT-A and MT-B) and heat shock proteins-70 (HSP-70a and HSP-70b). Interestingly, each MT and HSP-70 mRNA isoform responded differently in various target organs of fish following dietary cadmium exposure. Fish exposed to dietary cadmium also exhibited an increase in the hepatic transferrin mRNA level as well as the plasma transferrin protein level, indicating the role of transferrin in cadmium handling in fish. Importantly, an iron-supplemented diet reduced cadmium burden in the gut and the whole-body, and ameliorated the expression of MT and HSP-70 genes in fish. These results suggested the protective effects of elevated dietary iron against chronic dietary cadmium toxicity in fish. Overall, findings from the present research project provided novel and important physiological and molecular insights into the uptake, interactions and homeostasis of dietary divalent metals in freshwater fish. This information greatly enhances our current understanding of the toxicological implications for dietary metal exposure in metal contaminated wild fish populations, and may ultimately help the regulators to develop better strategies for ecological risk assessment of metals.

No description available.