Development of a Personalized Tumor Neoantigen Based Vaccine Formulation (FRAME-001) for Use in a Phase II Trial for the Treatment of Advanced Non-Small Cell Lung Cancer.

Stage III-IV non-small cell lung cancer (NSCLC) is a devastating disease characterized by a poor prognosis. NSCLC tumors carry genetic mutations, which can lead to the expression of altered protein sequences. Peptides originating from mutated proteins and bound to MHC molecules on the tumor cell surface are referred to as neoantigens, as they are tumor-specific and not expressed in normal cells. Due to their tumor specificity, neoantigens have a strong potential to induce an anti-tumor immune response and have been investigated for development of personalized therapeutic cancer vaccines. The current study describes the development of a clinical grade neoantigen vaccine formulation (FRAME-001) intended as immunotherapy in advanced NSCLC in combination with the immune checkpoint inhibitor pembrolizumab. The detection of aberrant tumor-specific transcripts as well as an algorithm to select immunogenic neoantigen peptides are described. Subsequently, selected neoantigen peptides were synthesized with a high throughput synthesis platform and aseptically formulated under good manufacturing practice (GMP) conditions into four aqueous peptides mixtures that each contained six neoantigen peptides. A validated stability-indicating analytical method was developed in which we considered the personalized nature of the formulation. An extensive stability study performed either at -25 °C or -80 °C showed that the formulation was stable for up to 32 weeks. The formulation was mixed with the vaccine adjuvant Montanide ISA 51 VG, which yielded the final vaccine emulsion. The stability of the vaccine emulsion was demonstrated using microscopic examination, differential light scattering, and the water-drop test. The presented data show that FRAME-001 is a feasible personalized vaccine formulation for the treatment of stage III-IV NSCLC. The presented data may give guidance in the development of novel personalized therapeutic vaccines since this formulation strategy could be used for any cancer indication.

Development of a Canadian Food Composition Database of Gluten-Free Products.

Country-specific food composition data are needed for gluten-free (GF) food products to assess nutritional adequacy and diet quality. This research aimed to develop a comprehensive GF food composition database for key GF foods consumed in Canada. Average nutrient data from 167 products were estimated from Nutrition Fact Panel labels and the commercial ingredient list, using an iterative and systematic approach. The database reports mean values for energy and 29 nutrients per 100 g for 33 GF commercial grain-based foods. Nutrient values were evaluated with Health Canada's nutrient content claims per standard reference serving. On average, GF products were, at minimum, a source of thiamin (73%), riboflavin (70%), niacin (58%), iron (58%), fibre (55%), magnesium (48%), folate (36%), zinc (19%), and calcium (15%). Most GF products were low in saturated fat (85%) and cholesterol (64%) but only 15% were low in total fat and 6% were free of sugar. Micronutrient enrichment and the use of nutrient-dense whole grain flours, legume flours, oil seed husks, and functional fibre ingredients varied within and between categories and brands but appeared to contribute to nutrient content. This database provides a new tool to enhance GF diet assessment in individuals or populations in Canada.

Grain Products Are a Top Source of Energy and Nutrients among Nova Scotian Adults Following a Gluten-Free Diet.

To determine the food sources of energy and 13 core nutrients, 89 diet recalls were analyzed from an explanatory mixed-methods pilot study with adults following a gluten-free diet (GFD) for any reason. Nonconsecutive dietary recalls were collected through a web-based, Automated Self-Administered 24-Hour (ASA24®-Canada-2016) Tool. Mean nutrient intakes were compared with Dietary Reference Intakes. Food items (excluding supplements) were extracted and categorized according to the Bureau of Nutritional Sciences Food Group Codes. Percentages of total dietary intakes from food sources were ranked. Grain products were the highest ranked contributor of energy (21.4%), carbohydrate (30.3%), fibre (29.1%), and iron (35.3%). Breakfast cereals, hot cereals, yeast breads, and mixed grain dishes (mainly rice or pasta-based) were the most important nutrient contributors for grains, despite most (64.3%) commercial cereals and breads being unenriched. Legumes and seeds were not frequently consumed. Nutrient density in the GFD could be improved with more emphasis on gluten-free (GF) whole grains, legumes, seeds, and enriched breads and cereals. More research is needed on the nutrient composition of GF foods to identify food sources of folate, other B vitamins, zinc and magnesium-nutrients of concern for those requiring a GFD.

Food sources of energy and nutrients among Canadian adults following a gluten-free diet.

BACKGROUND: The gluten-free diet (GFD) involves the elimination of wheat and related grains. Wheat is a key fortification vehicle for nutrients such as iron and B vitamins. While there is growing evidence of low nutrients intake and poor diet quality amongst people following long-term GFD, few studies have used a dietary pattern approach to analyse top food sources of nutrients in today's complex food environment. Thus, the purpose of this study was to identify food sources of energy and nutrients from previously collected diet records of adults following a GFD. METHODS: Three, 3-day food records were collected from 35 participants in a lifestyle intervention study (n = 240 records). All food items were categorised according to the Bureau of Nutritional Sciences Food Group Codes. Percentages of total dietary intakes from food groups were ranked. RESULTS: Mean intakes of dietary fibre, calcium and iron (females) were lower than recommended, with half the sample consuming below the recommended proportion of energy as carbohydrate. Meat, poultry and fish were the top source of energy (19.5%) in the diet. Gluten-free (GF) grain products were the top source of carbohydrate, fibre and iron and second greatest source of energy. Amongst grains, breakfast/hot cereals, yeast breads, and mixed grain dishes were the greatest nutrient contributors, despite most commercial cereals and breads (65%) being unenriched. Legumes were not frequently consumed. CONCLUSIONS: GF grains were the top food source of carbohydrate, fibre and iron, despite few brands being enriched or fortified. It is a challenge to assess and monitor nutrient intakes on GFD due to the lack of nutrient composition data for B vitamins and minerals (other than iron). Dietary planning guidance for the appropriate replacement of nutrients provided by wheat is warranted.

Folate Content and Chemical Composition of Commercially Available Gluten-Free Flour Alternatives.

Concerns about the nutritional and sensory qualities of gluten-free (GF) products has generated interest in the evaluation of novel gluten-free ingredients. Folate content is of particular interest due to limited sources of enriched folic acid in a GF diet as well as lack of nutrient composition data in novel flours. The aim of this study was to determine the total folate content and chemical composition of GF flours commercially available in Canada. A tri-enzyme method was used to extract folate from the flour samples, and a microbiological assay was used to measure the total folate contents. The chemical compositions of the GF flours were determined according to standard Association of Official Agricultural Chemists (AOAC) International methods. Compared to all-purpose flour, 265 ± 6.9 µg/100 (dry-weight basis), chickpea flour registered the highest folate content 451 ± 10.8 µg/100 (dry-weight basis) followed by quinoa flour, 174 ± 12.4 µg/ 100 g folate (dry-weight basis). Fonio, had a total starch content of ~77% but was not a source of folate. Flaxseed, chickpea, chia and coconut flours had the highest reported protein contents (mean value: 21.3 ± 1.3%) whereas flaxseed (~42%), and chia (~35%), had the highest lipid content. These findings may inform the selection of gluten-replacement flours with acceptable nutritional properties.

Adults following a gluten-free diet report little dietary guidance in a pilot survey exploring relationships between dietary knowledge, management, and adherence in Nova Scotia, Canada.

The strict nature of a gluten-free diet (GFD) poses a challenge for patient adherence and for clinicians to provide comprehensive client-centered care. Evidence on the relationship between nutrition knowledge, food skills, dietary management, and adherence can guide healthcare professionals counseling patients following this diet. In this explanatory pilot study, a province-wide survey (phase I) with 68 community-dwelling Nova Scotians following a GFD was conducted to investigate relationships between personal, social, and health care factors and dietary adherence using a mixed-methods approach. A sub-sample of 19 survey respondents were interviewed (phase II) to explore contextual experiences related to GFD knowledge, food skills, dietary management, and adherence using a food literacy lens. Here, we report findings from phase I, in which 37 participants with self-reported celiac disease (CD) and 31 participants reporting non-celiac reasons for wheat restriction (NCWR) completed a detailed 41-item online questionnaire. Self-reported data combined for both CD and NCWR respondents showed 76% perceived their health status as good to excellent. Most (62%) reported not receiving GFD advice from a health professional. Respondents with higher frequency of intentional consumption of gluten were more likely to have fewer correct answers to a food label quiz (ρ = -0.44; P = .0002). Most participants (75%) made at least one error in identifying gluten-free and gluten-containing foods, which may lead to unintentional gluten consumption and/or unnecessarily restricting safe foods. Findings from this exploratory study suggest patients may lack adequate referrals and support within the health care system and the community, adding to individual challenges of GFD adherence.

Potential impact of restricted caribou (Rangifer tarandus) consumption on anemia prevalence among Inuit adults in northern Canada.

BACKGROUND: Caribou (Rangifer tarandus) is the top dietary source of iron and several micronutrients necessary for red blood cell production (erythropoiesis) in the contemporary diet of Inuit adults across Canada. Many caribou populations across the circumpolar north, however, have experienced dramatic declines in recent decades. Restricted access to caribou may negatively impact the nutrition and health of Inuit communities. METHODS: We used data from the Inuit Health Survey, a cross-sectional survey of 2550 Inuit adults in thirty-six communities across northern Canada (conducted in 2007-2008) to examine the relationship between caribou consumption, hemoglobin (Hb), and blood biomarkers of nutrient intake and contaminant exposure. Multivariable linear regression was used to investigate the potential public health impact of a theoretical restriction in caribou consumption, by estimating the response of Hb concentrations (and the attendant change in anemia prevalence), to theoretical changes in caribou consumption (with and without substitution of caribou with other country food meat). RESULTS: Mean (95% CI) daily caribou meat consumption differed by an order of magnitude 4.3 (3.9-4.7), 51.1 (48.5-53.8), and 236.7 (224.7-248.7) grams/day between tertiles of caribou consumption. Mean (95% CI) hemoglobin levels increased from 129.1 (128.1-130.2) g/L to 132.5 (131.3-133.7) g/L between the highest and lowest tertiles of caribou consumption. In multivariable regression analyses, average daily caribou meat consumption was positively associated (P< 0.001) with hemoglobin levels. This relationship translated into approximately 4 g/L hemoglobin increase in participants in the third tertile of caribou consumption. The overall prevalence of anemia observed in the study population was 26.5% (24.5 - 28.3%) and a modelled restriction in caribou consumption (i.e. caribou = 0) increased the overall prevalence of anemia by approximately 6%. The maximum negative effect of caribou restrictions was related to a complete restriction on caribou consumption, coupled with the substitution of caribou with other country food meat (35.4% prevalence). CONCLUSIONS: Given the importance of caribou to Inuit culture, health and wellbeing, and the high price of healthful market foods in remote northern communities, strategies to promote the sustainable harvest of country foods are urgently required to ensure the health and nutrition security of the Inuit, in the context of rapidly changing Arctic environments and ecosystems.

Canadian packaged gluten-free foods are less nutritious than their regular gluten-containing counterparts.

BACKGROUND: A strict gluten-free (GF) diet is required for the management of celiac disease (CD). The nutritional adequacy of this diet has been questioned due to the elimination of wheat, an important vehicle for micronutrient fortification and source of fibre. While novel and/or reformulated packaged GF products have rapidly entered the marketplace, providing alternatives to wheat-based staples, it is unknown whether these new products are nutritionally comparable. METHODS: From a database of 3,851 foods collected across 21 grocery stores in Eastern Canada, we compared the nutrient content of 398 unique GF items with 445 gluten-containing (GC) equivalents. Wilcoxon rank tests were conducted on listed nutrient content (g, mg, µg) per 100 g of product and the nutrient contribution of iron, folate and fibre were evaluated using Health Canada's nutrient claim regulations. RESULTS: GF staples (cereals, breads, flours, pastas) contained 1.3 times more fat and less iron (by 55%), folate (by 44%) and protein (by 36%), than GC counterparts (P < 0.0001). On average, GF pastas had only 37% of the fibre in GC pastas (P < 0.0001). Notably, GF and GC flours were equivalent in nutrient content. Despite GF and GC flours having similar nutritional content, the vast majority of the processed GF foods fell short in key nutrients. DISCUSSION: Packaged GF foods in Canada are generally less nutritious than their GC counterparts, suggesting that GF diets should not be promoted to those who do not require it. The use of nutrient-dense GF flours in homemade foods may improve nutrient intakes on the GF diet.

Prevalence and Correlates of Food Insecurity among Students Attending a Small, Rural Canadian University.

PURPOSE: University students may be at risk for food insecurity (FI) due to low income coupled with rising tuition, housing, and food costs. This study aimed to determine the prevalence of FI and potential correlates among students at a small, rural Canadian university. METHODS: Health Canada's 10-item household food security survey module (HFSSM) was adapted to assess food security status within the postsecondary student population. An additional 11 items measured food access and demographics. The validated, web-based survey was distributed by email and completed by 218 students (15.6% response rate). Participants were classified as food secure, moderately food insecure, or severely food insecure using the HFSSM Adult scale. RESULTS: An overall FI rate of 37.2% was observed. This included 25.7% moderately food insecure and 11.5% severely food insecure. Students in higher years of study and who lived off campus had higher rates of FI. CONCLUSIONS: FI appears to be a significant concern for university students and has potential health and academic implications. Further research is needed to clarify the determinants and extent of FI for postsecondary students and to develop strategies to mitigate the prevalence and effects of food insecurity in these young adults.

Gluten-Free Foods in Rural Maritime Provinces: Limited Availability, High Price, and Low Iron Content.

We investigated the price difference between gluten-free (GF) and gluten-containing (GC) foods available in rural Maritime stores. GF foods and comparable GC items were sampled through random visits to 21 grocery stores in nonurban areas of Nova Scotia, New Brunswick, and Prince Edward Island, Canada. Wilcoxon rank tests were conducted on price per 100 g of product, and on the price relative to iron content; 2226 GF foods (27.2% staple items, defined as breads, cereals, flours, and pastas) and 1625 GC foods were sampled, with an average ± SD of 66 ± 2.7 GF items per store in rural areas and 331 ± 12 in towns. The median price of GF items ($1.76/100 g) was more expensive than GC counterparts ($1.05/100 g) and iron density was approximately 50% less. GF staple foods were priced 5% higher in rural stores than in town stores. Although the variety of GF products available to consumers has improved, higher cost and lower nutrient density remain issues in nonurban Maritime regions. Dietitians working in nonurban areas should consider the relative high price, difficult access, and low iron density of key GF items, and work together with clients to find alternatives and enhance their food literacy.

Prevalence of unexplained anaemia in Inuit men and Inuit post-menopausal women in Northern Labrador: International Polar Year Inuit Health Survey.

OBJECTIVE: To identify correlates of hemoglobin (Hb) and anaemia unexplained by iron deficiency (UA) in Canadian Inuit adults. METHODS: A cross-sectional survey assessed diet, demographic information, anthropometry, fasting Hb, ferritin, soluble transferrin receptor (on a subset), high-sensitivity C-reactive protein (hs-CRP) in serum, red blood cell (RBC) fatty acid composition, blood lead, and antibodies to Helicobacter pylori in non-pregnant, Inuit adults (n = 2550), ≥18 years of age from randomly selected households in 36 Inuit communities in Inuvialuit Settlement Region, Nunavut Territory and Nunatsiavut of Northern Labrador, Canada. RESULTS: Hb concentrations were lower and UA prevalence higher in Inuit men after 50 years of age. Rate of anaemia was constant among Inuit women but changed from primarily iron deficiency anaemia pre-menopause, to primarily UA in post-menopause. Low education levels and hs-CRP were associated with increased risk of UA. For Inuit men, % RBC eicosapentaenoic acid (EPA) and elevated blood lead were also associated with increased risk of UA. Frequency of traditional food intake was positively associated with Hb. CONCLUSION: Age patterns and regional variation of anaemia suggest that ethnicity-related physiological differences cannot explain anaemia prevalence for Inuit. High RBC EPA status, inflammation and infections, and lower education levels may contribute to the prevalence of anaemia in this population, which is not related to iron status. Thus, traditional lifestyle may protect Inuit from nutritional anaemia but contribute to lower Hb through environmental exposures. The clinical significance of UA for older Inuit adults requires further investigation, as the prevalence represents a moderate public health problem.

Higher n3-fatty acid status is associated with lower risk of iron depletion among food insecure Canadian Inuit women.

BACKGROUND: High rates of iron deficiency and anemia are common among Inuit and Arctic women despite a traditional diet based on animal source foods. However, representative data on iron status and relevant determinants for this population are lacking. The objectives were to determine the prevalence of anemia and depletion of iron stores, then to identify correlates of iron status in non-pregnant Canadian Inuit women. METHODS: In a cross-sectional survey of 1550 women in the International Polar Year Inuit Health Survey, 2007-2008, hemoglobin, serum ferritin, soluble transferrin receptor (on a subset), C-reactive protein (CRP), RBC fatty acid composition, and H pylori serology were analyzed on fasting venous blood. Sociodemographic, food security status, anthropometric, dietary, and health data were collected. Correlates of iron status were assessed with multivariate linear and logistic models. RESULTS: Anemia was observed in 21.7% and iron deficient erythropoiesis in 3.3% of women. For women with CRP ≤ 10 mg/L (n = 1260) 29.4% had depleted iron stores. Inadequate iron intakes were observed in 16% of premenopausal and <1% of postmenopausal women. Among food insecure women, higher long-chain (n-3) polyunsaturated fatty acid (LC-PUFA) status, which reflects a more traditional food pattern, was associated with reduced risk of iron depletion. CONCLUSIONS: Iron depletion and anemia are a concern for Inuit women despite adequate total dietary iron intake primarily from heme sources. The high prevalence of H. pylori exposure, together with dietary iron adequacy, suggests an inflammation-driven iron deficiency and mild anemia. The anti-inflammatory properties of LC-PUFA may be important for iron status in this population.

Traditional food intake is correlated with iron stores in Canadian Inuit men.

Accelerated loss of traditional lifestyles may place Inuit at risk of iron depletion given that anemia has been observed among Arctic men. The objectives of this study were to determine the prevalence of anemia, storage iron depletion, and iron overload and to identify correlates of iron status in Canadian Inuit men. In a cross-sectional survey of 994 men in the International Polar Year Inuit Health Survey, 2007-2008, hemoglobin, serum ferritin (SF), soluble transferrin receptor (on a subset), CRP, RBC fatty acid composition, and Helicobacter pylori serology were measured in venous blood drawn from fasting men. Anthropometric, dietary, sociodemographic, and health data were collected. Dietary and nondietary correlates of iron status were assessed with multiple linear and logistic models. For men with CRP ≤10 mg/L (n = 804), 6.5% had depleted, 19.8% had low, and 10.3% had elevated iron stores. Anemia was moderately prevalent (16.1%), but iron deficiency anemia was less common (2.4%). There was a low probability of dietary iron inadequacy (2.4% < Estimated Average Requirement) and excess iron intakes (10.7% > Tolerable Upper Intake Level). Food-insecure men and those without a household hunter had a higher risk of low or depleted iron stores. Adiposity, traditional food intake, long-chain RBC PUFA status, and inflammation were positively associated with SF and food insecurity, smoking, and H. pylori seropositivity were negatively associated with SF. Despite a moderate prevalence of anemia, iron stores are largely adequate in this population, although lower than expected based on iron intake. The regulation of iron metabolism in this population and the high prevalence of anemia in older men warrants further investigation.

Relationship between abnormal sperm morphology induced by dietary zinc deficiency and lipid composition in testes of growing rats.

The present study investigated the effect of dietary Zn deficiency during sexual maturation on sperm integrity and testis phospholipid fatty acid composition. Male weanling Sprague-Dawley rats were randomised into four dietary groups for 3 weeks: Zn control (ZC; 30 mg Zn/kg); Zn marginally deficient (ZMD; 9 mg Zn/kg); Zn deficient (ZD; < 1 mg Zn/kg); pair fed (PF; 30 mg Zn/kg) to the ZD group. Morphology of cauda epididymal sperm and lipid profiles of testis phospholipids were analysed. The rats fed the ZD diet had a lower testis weight (P < 0.02). Seminal vesicles and prostate weight were also lower in the ZD and PF groups. Rats fed the ZD diet, but not the ZMD diet, had 34-35 % more abnormal spermatozoa and 24 % shorter sperm tail length than the ZC and PF rats (P < 0.001). Testis cholesterol concentration was higher in the ZD rats compared with the ZC and PF rats (P < 0.04). Testes were highly enriched with n-6 fatty acids by showing n-6 : n-3 fatty acid ratios of 27:1 in phosphatidylcholine (PC) and 23:1 in phosphatidylethanolamine (PE). The dominant fatty acid in testes was docosapentaenoic acid (22 : 5n-6), comprising 15 and 24 % of PC and PE, respectively. This fatty acid was significantly lower in the ZD rats, whereas 18 : 2n-6 was higher compared with the rats in the other diet groups. These results demonstrate that severe Zn deficiency adversely affects sperm integrity and modulates testis fatty acid composition by interrupting essential fatty acid metabolism. This suggests that Zn deficiency-associated abnormal testicular function is perhaps preceded by altered membrane fatty acid composition, especially of a major fatty acid, 22 : 5n-6.

The paradox of anemia with high meat intake: a review of the multifactorial etiology of anemia in the Inuit of North America.

Anemia is a serious concern among indigenous populations in North America, and it appears to be widespread among the Inuit despite abundant intakes of heme iron. It is therefore hypothesized that anemia for the Inuit involves other dietary factors not usually associated with animal foods, such as low intakes of vitamin A and/or folate, riboflavin, and vitamin C. Also, Helicobacter pylori infection and/or parasitosis may result in gastrointestinal blood loss and/or functional iron deficiency. This review aims to describe factors that may cause anemia in Inuit populations despite high meat intakes, abundant bioavailable iron, and other important hematological nutrients.

Dietary long-chain inulin reduces abdominal fat but has no effect on bone density in growing female rats.

New strategies to improve Ca absorption and bone health are needed to address the current state of osteoporosis prevention and management. Inulin-type fructans have shown great promise as a dietary intervention strategy, but have not yet been tested in a young female model. Our objective was to investigate the effect of long chain (LC) inulin on bone mineralization and density in growing, female rats, as well as the quality of growth. Weanling Sprague-Dawley rats were assigned to inulin or cellulose treatments for either 4 or 8 weeks. Growth was measured weekly and quality of growth assessed using fat pad weights and dual-energy X-ray absorptiometry (DXA). Whole body (WB) and selected regions were analysed for bone mineral density (BMD) and body composition by DXA. Serum markers of bone turnover were assessed by enzyme-linked immunosorbent assays. Ca and P concentrations were determined in excised femurs by inductively coupled plasma spectrometry. Feeding inulin resulted in 4 % higher femoral weight (adjusted for body weight) and 6 % less feed intake. Inulin did not affect WB or regional BMD, but was associated with a 28 % lower parametrial fat pad mass, 21 % less WB fat mass and 5 % less WB mass. In summary, LC-inulin lowered body fat mass, without consequence to bone density in growing female rats.

Dietary zinc attenuates renal lead deposition but metallothionein is not directly involved.

Chronic lead exposure irreversibly damages the kidneys and may be associated with hypertension and renal insufficiency at sub-clinically toxic levels. Zinc supplementation reduces lead absorption and tissue retention in rodent models but the mechanisms are unknown. Metallothionein (MT) may function in lead detoxification. Our objective was to investigate the effects of marginal zinc (MZ) and supplemental zinc (SZ) intakes on renal lead and zinc accumulation, renal MT immunolocalization and levels. Weanling Sprague Dawley rats were assigned to MZ (8 mg Zn/kg diet), zinc-adequate control (CT; 30 mg Zn/kg), zinc-adequate diet-restricted (DR; 30 mg Zn/kg) or SZ (300 mg Zn/kg) groups, with and without lead acetate-containing drinking water (200 mg Pb/L) for 3 weeks. Kidneys were analyzed for lead and zinc by inductively coupled plasma spectroscopy and MT by immunolocalization and Western blotting. MZ had higher renal lead and lower renal zinc concentrations than CT. SZ was more protective than CT against renal lead accumulation. Renal MT levels reflected dietary intake (SZ > or = DR > or = CT > or = MZ) but lead had no effect on MT staining intensity, distribution, or relative protein amounts. In summary, while SZ lowered renal lead concentration, MT did not appear to function in renal lead accumulation. Future studies should explore alternate mechanisms of renal lead detoxification.

Lead does not affect transcription of intestinal zinc-binding proteins in growing rats.

Environmental lead exposure remains a serious concern for the growth and development of children. Micronutrient status may affect the absorption and tissue accumulation of lead, but the mechanisms of gastrointestinal uptake and transport remain unknown. Thus, our objective was to investigate the effects of lead on the mRNA levels of intestinal zinc transporter 4 (ZIP4), metallothionein (MT), cysteine-rich intestinal protein (CRIP), and divalent metal transporter 1 (DMT1) in growing rats fed marginal, adequate, and supplemental zinc diets. Weanling Sprague Dawley rats were assigned to marginal zinc (MZ; 8 mg Zn/kg diet), zinc-adequate control (CT; 30 mg Zn/kg), zinc-adequate diet-restricted (DR; 30 mg Zn/kg), or supplemental zinc (SZ; 300 mg Zn/kg) groups, with and without lead acetate-containing drinking water (200 mg Pb/l) for 3 weeks. Duodenum was analyzed for ZIP4, MT, CRIP, and DMT1 mRNA levels by real-time reverse transcription-polymerase chain reaction and MT immunolocalization. Tissues were analyzed for zinc, lead, and iron by inductively coupled plasma spectrometry. MZ rats had higher duodenal ZIP4 mRNA levels, lower MT mRNA levels, lower MT immunostaining intensity, and lower zinc concentrations than DR, CT, and SZ. Duodenal DMT1 mRNA levels were lower in DR and SZ compared with MZ. Tissue lead concentrations responded to dietary zinc with SZ < CT < DR

Marginal zinc deficiency exacerbates bone lead accumulation and high dietary zinc attenuates lead accumulation at the expense of bone density in growing rats.

Environmental lead exposure is associated with reduced bone growth and quality, which may predispose to osteoporosis. Zinc supplementation may reduce lead accumulation; however, effects on bone development have not been addressed. Our objective was to investigate the effects of marginal zinc (MZ) and supplemental zinc (SZ) intakes on bone lead deposition and skeletal development in lead-exposed rats. In a factorial design, weanling Sprague-Dawley rats were assigned to MZ (8 mg/kg diet); zinc-adequate control (CT; 30 mg/kg); zinc-adequate, diet-restricted (DR; 30 mg/kg); or SZ (300 mg/kg) groups, with and without lead acetate-containing drinking water (200 mg Pb/l) for 3 weeks. Excised femurs were analyzed for bone mineral density (BMD) by dual-energy x-ray absorptiometry, morphometry, and mineral content. MZ had higher femur lead and lower femur zinc concentrations and impaired skeletal growth and mineralization than CT. DR inhibited growth but did not result in higher femur lead concentrations than CT. SZ had higher femur zinc and lower femur lead concentrations than the other treatments. DR and SZ had impaired BMD versus CT and MZ. Lead also retarded skeletal growth and impaired BMD, but an interaction between lead and MZ was only found for femoral knee width, which was lower in MZ exposed to lead. In summary, while MZ deficiency exacerbated bone lead concentration, it generally did not intensify lead toxicity. SZ was protective against bone lead but was detrimental to BMD, suggesting that the optimal level of SZ to reduce lead absorption, while supporting growth and bone development, requires further investigation.