Nutritional assessment among adult patients with suspected or confirmed active tuberculosis disease in rural India

OBJECTIVES

Our study goal was to evaluate a set of nutritional indicators among adults with confirmed or suspected active tuberculosis disease in southern India, given the limited literature on this topic. Study objectives were to assess the: I) double burden of malnutrition at individual and population levels; II) relative performance of anthropometric indicators (body mass index, waist circumference) in diabetes screening; and III) associations between vitamin D and metabolic abnormalities.

DESIGN

Cross-sectional study.

SETTING

Hospital in rural southern India.

PARTICIPANTS

Among adult patients (n = 834), we measured anthropometry, body composition, and biomarkers (vitamin D, glycated hemoglobin, hemoglobin) of nutritional status. Subsets of participants provided blood and sputum samples.

RESULTS

Among participants, 91.7% had ≥ 1 malnutrition indicator; 34.6% had both undernutrition and overnutrition indicators. Despite the fact that >80% of participants would be considered low-risk in diabetes screening based on low body mass index and waist circumference, approximately one-third had elevated glycated hemoglobin (≥ 5.7%). The lowest quintile of serum 25-hydroxyvitamin D was associated with an increased risk of glycated hemoglobin ≥ 5.7% (adjusted risk ratio 1.61 [95% CI 1.02, 2.56]) compared to the other quintiles, adjusting for age and trunk fat.

CONCLUSIONS

Malnutrition and diabetes were prevalent in this patient population; since both can predict poor prognosis of active tuberculosis disease, including treatment outcomes and drug resistance, this emphasizes the importance of dual screening and management of under- and overnutrition-related indicators among patients with suspected or active tuberculosis disease. Further studies are needed to determine clinical implications of vitamin D as a potential modifiable risk factor in metabolic abnormalities, and whether population-specific body mass index and waist circumference cut-offs improve diabetes screening.

Vitamin D assays and the definition of hypovitaminosis D: results from the First International Conference on Controversies in Vitamin D

The First International Conference on Controversies in Vitamin D was held in Pisa, Italy, 14-16 June 2017. The meeting's purpose was to address controversies in vitamin D research, review the data available, to help resolve them, and suggest a research agenda to clarify areas of uncertainty. The serum 25-hydroxyvitamin D [25(OH)D] concentration [i.e. the sum of 25(OH)D3 and 25(OH)D2 ] remains the critical measurement for defining vitamin D status. Assay variation for 25(OH)D has contributed to the current chaos surrounding efforts to define hypovitaminosis D. An essential requirement to develop a consensus on vitamin D status is that measurement of 25(OH)D and, in the future, other potential vitamin D biomarkers [e.g. 1α,25(OH)2 D3 , 3-epi-25(OH)D, 24,25(OH)2 D3, vitamin D-binding protein, free/bioavailable 25(OH)D and parathyroid hormone] be standardized/harmonized, to allow pooling of research data. Vitamin D Standardization Program tools are described and recommended for standardizing 25(OH)D measurement in research. In the future, similar methodology, based on National Institute for Standards and Technology standard reference materials, must be developed for other candidate markers of vitamin D status. Failure to standardize/harmonize vitamin D metabolite measurements is destined to promulgate continued chaos. At this time, 25(OH)D values below 12 ng ml-1 (30 nmol l-1 ) should be considered to be associated with an increased risk of rickets/osteomalacia, whereas 25(OH)D concentrations between 20 ng ml-1 and 50 ng ml-1 (50-125 nmol l-1 ) appear to be safe and sufficient in the general population for skeletal health. In an effort to bridge knowledge gaps in defining hypovitaminosis D, an international study on rickets as a multifactorial disease is proposed.

Iron Supplementation during Pregnancy and Infancy: Uncertainties and Implications for Research and Policy

Iron is particularly important in pregnancy and infancy to meet the high demands for hematopoiesis, growth and development. Much attention has been given to conditions of iron deficiency (ID) and iron deficient anemia (IDA) because of the high global prevalence estimated in these vulnerable life stages. Emerging and preliminary evidence demonstrates, however, a U-shaped risk at both low and high iron status for birth and infant adverse health outcomes including growth, preterm birth, gestational diabetes, gastrointestinal health, and neurodegenerative diseases during aging. Such evidence raises questions about the effects of high iron intakes through supplementation or food fortification during pregnancy and infancy in iron-replete individuals. This review examines the emerging as well as the current understanding of iron needs and homeostasis during pregnancy and infancy, uncertainties in ascertaining iron status in these populations, and issues surrounding U-shaped risk curves in iron-replete pregnant women and infants. Implications for research and policy are discussed relative to screening and supplementation in these vulnerable populations, especially in developed countries in which the majority of these populations are likely iron-replete.

Ethnic and genetic factors of iron status in women of reproductive age

Background: African Americans are at increased risk of iron deficiency (ID) but also have higher serum ferritin (SF) concentrations than those of the general population. The Hemochromatosis and Iron Overload Screening (HEIRS) Study was a multicenter study of ethnically diverse participants that tested for the hemochromatosis (HFE) C282Y genotype and iron status.Objective: We sought to determine the prevalence and predictors of ID (SF concentration ≤15 μg/L) and elevated iron stores (SF concentration >300 μg/L) in HEIRS women of reproductive age (25-44 y).Design: The HEIRS Study was a cross-sectional study of iron status and HFE mutations in primary care patients at 5 centers in the United States and Canada. We analyzed data for women of reproductive age according to whether or not they were pregnant or breastfeeding at the time of the study.Results: ID was present in 12.5% of 20,080 nonpregnant and nonbreastfeeding women compared with 19.2% of 1962 pregnant or breastfeeding women (P < 0.001). Asian American ethnicity (OR ≤0.9; P ≤ 0.049) and HFE C282Y (OR ≤0.84; P ≤ 0.060) were independently associated with a decreased risk of ID in nonpregnant and nonbreastfeeding women and in pregnant or breastfeeding women. Hispanic ethnicity (OR: 1.8; P < 0.001) and African American ethnicity (OR: 1.6; P < 0.001) were associated with an increased risk of ID in nonpregnant and nonbreastfeeding women. Elevated iron stores were shown in 1.7% of nonpregnant and nonbreastfeeding women compared with 0.7% of pregnant or breastfeeding women (P = 0.001). HFE C282Y homozygosity had the most marked independent association with elevated iron stores in nonpregnant and nonbreastfeeding women and in pregnant or breastfeeding women (OR >49.0; P < 0.001), but African American ethnicity was also associated with increased iron stores in both groups of women (OR >2.0; P < 0.001). Asian American ethnicity (OR: 1.8; P = 0.001) and HFE C282Y heterozygosity (OR: 1.9; P = 0.003) were associated with increased iron stores in nonpregnant and nonbreastfeeding women.Conclusions: Both ID and elevated iron stores are present in women of reproductive age and are influenced by ethnicity and HFE C282Y. Efforts to optimize iron status should keep these findings in view. This study was registered at clinicaltrials.gov as NCT03276247.

Integrating themes, evidence gaps, and research needs identified by workshop on iron screening and supplementation in iron-replete pregnant women and young children

This report addresses the evidence and the uncertainties, knowledge gaps, and research needs identified by participants at the NIH workshop related to iron screening and routine iron supplementation of largely iron-replete pregnant women and young children (6-24 mo) in developed countries. The workshop presentations and panel discussions focused on current understanding and knowledge gaps related to iron homeostasis, measurement of and evidence for iron status, and emerging concerns about supplementing iron-replete members of these vulnerable populations. Four integrating themes emerged across workshop presentations and discussion and centered on 1) physiologic or developmental adaptations of iron homeostasis to pregnancy and early infancy, respectively, and their implications, 2) improvement of the assessment of iron status across the full continuum from iron deficiency anemia to iron deficiency to iron replete to iron excess, 3) the linkage of iron status with health outcomes beyond hematologic outcomes, and 4) the balance of benefit and harm of iron supplementation of iron-replete pregnant women and young children. Research that addresses these themes in the context of the full continuum of iron status is needed to inform approaches to the balancing of benefits and harms of screening and routine supplementation.

Iron status in pregnant women and women of reproductive age in Europe

Understanding the iron status in pregnant women in Europe provides a foundation for considering the role of iron screening and supplementation. However, available reports and studies have used different approaches that challenge the devising of overall summaries. Moreover, data on pregnant women are limited, and thus, data on women of reproductive age provide useful background information including baseline iron stores in pregnant women. This review considered data that are available from >15 European countries including national surveys and relevant clinical studies. In European women of reproductive age, median or geometric mean serum ferritin (SF) concentrations were estimated at 26-38 μg/L. Approximately 40-55% of this population had small or depleted iron stores (i.e., SF concentration ≤30 μg/L), and 45-60% of this population had apparently replete iron stores. The prevalence of iron deficiency (ID) and iron deficiency anemia (IDA) was 10-32% and 2-5%, respectively, depending on the cutoffs used. Approximately 20-35% of European women of reproductive age had sufficient iron stores (SF concentration >70 μg/L) to complete a pregnancy without supplementary iron. During pregnancy, European women in controlled supplementation trials who were not receiving iron supplements displayed increasing prevalences of ID and IDA during pregnancy, which peaked in the middle to late third trimester. Available evidence has suggested that, in gestational weeks 32-39, the median or geometric mean SF concentrations were 6-21 μg/L, and prevalences of ID and IDA were 28-85% and 21-35%, respectively. Women who were taking iron supplements had higher iron status and lower prevalences of ID and IDA, which were dependent on the dose of iron and compliance. The data suggest that, in Europe, the iron status of reproductive-aged women varies by region and worsens in pregnancy without iron supplementation.

Placental vitamin D metabolism and its associations with circulating vitamin D metabolites in pregnant women

Background: Little is known about placental vitamin D metabolism and its impact on maternal circulating vitamin D concentrations in humans.Objective: This study sought to advance the current understanding of placental vitamin D metabolism and its role in modulating maternal circulating vitamin D metabolites during pregnancy.Design: Nested within a feeding study, 24 healthy pregnant women (26-29 wk of gestation) consumed a single amount of vitamin D (511 IU/d from diet and a cholecalciferol supplement) for 10 wk. Concentrations of placental and blood vitamin D metabolites and placental messenger RNA (mRNA) abundance of vitamin D metabolic pathway components were quantified. In addition, cultured human trophoblasts were incubated with ¹³C-cholecalciferol to examine the intracellular generation and secretion of vitamin D metabolites along with the regulation of target genes.Results: In placental tissue, 25-hydroxyvitamin D₃ [25(OH)D₃] was strongly correlated (r = 0.83, P < 0.001) with 24,25-dihydroxyvitamin D₃ Moreover, these placental metabolites were strongly correlated (r ≤ 0.85, P ≤ 0.04) with their respective metabolites in maternal circulation. Positive associations (P ≤ 0.045) were also observed between placental mRNA abundance of vitamin D metabolic components and circulating vitamin D metabolites [i.e., LDL-related protein 2 (LRP2, also known as megalin) with 25(OH)D₃ and the C3 epimer of 25(OH)D₃ [3-epi-25(OH)D₃]; cubilin (CUBN) with 25(OH)D₃; 25-hydroxylase (CYP2R1) with 3-epi-25(OH)D₃; 24-hydroxylase (CYP24A1) with 25(OH)D₃, 3-epi-25(OH)D₃, and 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃]; and 1α-hydroxylase [(CYP27B1) with 3-epi-25(OH)D₃ and 1,25(OH)₂D₃]. Notably, in vitro experiments with trophoblasts showed increased production and secretion of 25(OH)D₃ and higher CYP24A1 gene transcript abundance in response to cholecalciferol treatment.Conclusions: The numerous associations of many of the placental biomarkers of vitamin D metabolism with circulating vitamin D metabolites among pregnant women [including a CYP27B1-associated increase in 1,25(OH)₂D₃] and the evidence of trophoblast production and secretion of vitamin D metabolites, especially 25(OH)D₃, suggest that the placenta may play an active role in modulating the vitamin D metabolite profile in maternal circulation in human pregnancy. This trial was registered at clinicaltrials.gov as NCT03051867.

Vitamin D: Moving Forward to Address Emerging Science

The science surrounding vitamin D presents both challenges and opportunities. Although many uncertainties are associated with the understandings concerning vitamin D, including its physiological function, the effects of excessive intake, and its role in health, it is at the same time a major interest in the research and health communities. The approach to evaluating and interpreting the available evidence about vitamin D should be founded on the quality of the data and on the conclusions that take into account the totality of the evidence. In addition, these activities can be used to identify critical data gaps and to help structure future research. The Office of Dietary Supplements (ODS) at the National Institutes of Health has as part of its mission the goal of supporting research and dialogues for topics with uncertain data, including vitamin D. This review considers vitamin D in the context of systematically addressing the uncertainty and in identifying research needs through the filter of the work of ODS. The focus includes the role of systematic reviews, activities that encompass considerations of the totality of the evidence, and collaborative activities to clarify unknowns or to fix methodological problems, as well as a case study using the relationship between cancer and vitamin D.

Introduction to workshop on iron screening and supplementation in iron-replete pregnant women and young children

The NIH Office of Dietary Supplements convened a public workshop on iron screening and supplementation in iron-replete pregnant women and young children in 2016 in Bethesda, Maryland. The starting point for the workshop was the recent reports from the US Preventive Services Task Force concluding that there was insufficient evidence to evaluate the benefits and harms associated with iron screening and routine supplementation among asymptomatic pregnant women and young children (6-24 mo old) in the United States. The goal of the workshop was to explore and refine understanding about the existing knowledge gaps and research needs associated with these preventive services for these groups. Given the focus on the United States, planning for the workshop took into account the higher iron status in the United States compared with developing countries and, in turn, included a focus on iron-replete individuals consistent with the U-shaped risk curve for nutrient-health relations. Topic areas included adaptations in iron homeostasis associated with pregnancy and young childhood, the impact of inflammation, measurement of iron status, current estimates of iron status for pregnant women and young children in the United States and in Europe, and emerging evidence suggesting adverse effects associated with iron supplementation of iron-replete individuals. A crosscutting dialogue conducted at the close of the workshop formed the basis for a workshop summary that specified evidence gaps and research needs in a range of areas centered on the relation of these adaptations of iron homeostasis with the response to and risk from iron supplementation as well as the need for indicators informative of the full continuum of iron status and based on health outcomes, not just erythropoiesis.

Baseline Assessment of 25-Hydroxyvitamin D Reference Material and Proficiency Testing/External Quality Assurance Material Commutability: A Vitamin D Standardization Program Study

The Vitamin D Standardization Program (VDSP) coordinated a study in 2012 to assess the commutability of reference materials and proficiency testing/external quality assurance materials for total 25-hydroxyvitamin D [25(OH)D] in human serum, the primary indicator of vitamin D status. A set of 50 single-donor serum samples as well as 17 reference and proficiency testing/external quality assessment materials were analyzed by participating laboratories that used either immunoassay or LC-MS methods for total 25(OH)D. The commutability test materials included National Institute of Standards and Technology Standard Reference Material 972a Vitamin D Metabolites in Human Serum as well as materials from the College of American Pathologists and the Vitamin D External Quality Assessment Scheme. Study protocols and data analysis procedures were in accordance with Clinical and Laboratory Standards Institute guidelines. The majority of the test materials were found to be commutable with the methods used in this commutability study. These results provide guidance for laboratories needing to choose appropriate reference materials and select proficiency or external quality assessment programs and will serve as a foundation for additional VDSP studies.

Maternal vitamin D biomarkers are associated with maternal and fetal bone turnover among pregnant women consuming controlled amounts of vitamin D, calcium, and phosphorus

Vitamin D plays a central role in calcium homeostasis; however, its relationship with bone turnover during pregnancy remains unclear due to a lack of studies that have rigorously controlled for vitamin D and other nutrients known to influence bone metabolism. Similarly, prior investigations of the effect of pregnancy on bone turnover relative to the nonpregnant state may have been confounded by varying intakes of these nutrients. Nested within a controlled intake study, the present investigation sought to quantify associations between maternal vitamin D biomarkers and biochemical markers of bone turnover among pregnant (versus nonpregnant) women and their fetuses under conditions of equivalent and adequate intakes of vitamin D and related nutrients. Changes in markers of bone turnover across the third trimester were also examined. Healthy pregnant (26-29 wk gestation; n=26) and nonpregnant (n=21) women consumed 511IU vitamin D/d, 1.6g calcium/d, and 1.9g phosphorus/d for 10weeks while participating in a controlled feeding study featuring two choline doses. Based on linear mixed models adjusted for influential covariates (e.g., BMI, ethnicity, and season), pregnant women had 50-150% higher (P<0.001) concentrations of bone resorption markers than nonpregnant women. Among pregnant women, increases in maternal 25(OH)D across the study period were associated (P<0.020) with lower osteocalcin and deoxypyridinoline at study-end, and higher fetal osteocalcin. In addition, maternal free 25(OH)D, 1,25(OH)₂D and 24,25(OH)₂D tended to be negatively associated (P≤0.063) with maternal NTx at study-end, and maternal free 25(OH)D and 24,25(OH)₂D were positively associated (P≤0.021) with fetal CTx. Similarly, maternal 3-epi-25(OH)D₃ was negatively related (P≤0.037) to maternal NTx and deoxypyridinoline at study-end. These declines in bone resorption markers resulting from higher vitamin D biomarker concentrations among pregnant women coincided with increases in their albumin-corrected serum calcium concentrations, indicating that calcium transfer to the fetus was uncompromised. Notably, none of these associations achieved statistical significance among nonpregnant women. Overall, our study findings suggest that achieving higher maternal concentrations of vitamin D biomarkers might attenuate third-trimester bone resorption while ensuring sufficient calcium delivery to the fetus.

Scanning for new evidence to prioritize updates to the Dietary Reference Intakes: case studies for thiamin and phosphorus

BACKGROUND

Dietary Reference Intakes (DRIs) are fundamental to inform national nutrition policy. However, a regular systematic review of the 51 nutrients that have DRIs has limited feasibility, and many DRIs have not been reviewed in >15 y.

OBJECTIVE

To address this issue, individuals (nutrient review group) who were members of the Food and Nutrition Board developed a streamlined, evidence-based methodology that could be used to identify nutrients potentially in need of a systematic review.

DESIGN

The proposed methodology, termed an evidence scan, comprises several steps. First, an analytic framework is developed to identify markers of associations between intake of a nutrient and a corresponding clinical outcome. Next, the framework is used to direct the identification of keywords for a scan of published research that is potentially relevant to intake requirements or upper intake levels for a nutrient. Last, a panel of content experts selects the abstracts that are likely to be relevant and reviews the full publications. The results may be used to determine whether a revision of the nutrient's DRI is an immediate priority but would not supplant a comprehensive systematic evidence review.

RESULTS

To illustrate the process, 2 nutrients were selected as case studies: thiamin and phosphorus (DRIs were last set in 1998 and 1997, respectively). Using the evidence scan for thiamin, we identified 70 potentially relevant abstracts, of which 9 full publications were reviewed. For phosphorus, 127 potentially relevant abstracts were identified, and 29 full publications were reviewed.

CONCLUSIONS

From the review of these 2 nutrients, the nutrient review group concluded that there was insufficient new evidence to assign a high priority to a comprehensive systematic review for either thiamin or phosphorus. Evidence scanning is an efficient method of identifying DRI nutrients that are most in need of either a new or an updated systematic review.

Vitamin D Metabolism Varies among Women in Different Reproductive States Consuming the Same Intakes of Vitamin D and Related Nutrients

BACKGROUND

The impact of the reproductive state on vitamin D metabolism and requirements is uncertain in part because of a lack of studies with controlled dietary intakes of vitamin D and related nutrients.

OBJECTIVE

We aimed to quantify the impact of the reproductive state on a panel of vitamin D biomarkers among women of childbearing age consuming equivalent amounts of vitamin D and related nutrients.

METHODS

Nested within a feeding study providing 2 doses of choline, healthy pregnant (26-29 wk gestation; n = 26), lactating (5 wk postpartum; n = 28), and control (nonpregnant/nonlactating; n = 21) women consumed a single amount of vitamin D (511 ± 48 IU/d: 311 ± 48 IU/d from diet and 200 IU/d as supplemental cholecalciferol) and related nutrients (1.6 ± 0.4 g Ca/d and 1.9 ± 0.3 g P/d) for 10 wk. Vitamin D biomarkers were measured in blood obtained at baseline and study end, and differences in biomarker response among the reproductive groups were assessed with linear mixed models adjusted for influential covariates (e.g., body mass index, season, race/ethnicity).

RESULTS

At study end, pregnant women had higher (P < 0.01) circulating concentrations of 25-hydroxyvitamin D [25(OH)D; 30%], 1,25-dihydroxyvitamin D [1,25(OH)2D; 80%], vitamin D binding protein (67%), and C3 epimer of 25(OH)D3 (100%) than control women. Pregnant women also had higher (P ≤ 0.04) ratios of 25(OH)D to 24,25-dihydroxyvitamin D [24,25(OH)2D; 40%] and 1,25(OH)2D to 25(OH)D (50%) than control women. In contrast, no differences (P ≥ 0.15) in vitamin D biomarkers were detected between the lactating and control groups. Notably, the study vitamin D dose of 511 IU/d achieved vitamin D adequacy in most participants (95%) regardless of their reproductive state.

CONCLUSIONS

The higher concentrations of vitamin D biomarkers among pregnant women than among control women suggest that metabolic adaptations, likely involving the placenta, transpire to enhance vitamin D supply during pregnancy. The study findings also support the adequacy of the current vitamin D RDA of 600 IU for achieving serum 25(OH)D concentrations ≥50 nmol/L among women differing in their reproductive state. This trial was registered at clinicaltrials.gov as NCT01127022.

Genetic and environmental factors are associated with serum 25-hydroxyvitamin D concentrations in older African Americans

BACKGROUND

Low circulating 25-hydroxyvitamin D [25(OH)D] is prevalent in African Americans, but predictors of vitamin D status are understudied compared to Caucasian populations.

OBJECTIVE

We investigated whether certain environmental and genetic factors are predictors of circulating 25(OH)D in 989 elderly African Americans participating in the Health, Aging, and Body Composition (Health ABC) Study.

METHODS

Regression analysis estimated the cross-sectional association of nongenetic (environmental) factors with 25(OH)D. Single nucleotide polymorphisms (SNPs) associated with 25(OH)D in Caucasian genome-wide association studies (GWASs) were analyzed for association with serum 25(OH)D, including analyses of all imputed SNPs in identified genomic regions. Genome-wide complex trait analysis (GCTA) evaluated the association of all (genome-wide) genotyped SNPs with serum 25(OH)D in the Health ABC Study with replication in the Multi-Ethnic Study of Atherosclerosis (MESA) cohort.

RESULTS

Gender, study site, season of blood draw, body mass index, dietary supplement use, dairy and cereal consumption, Healthy Eating Index score, and walking >180 min/wk were associated with 25(OH)D (P < 0.05), jointly explaining 25% of the variation in circulating 25(OH)D. Multivitamin supplement use was the strongest predictor of circulating 25(OH)D, and supplement users had a 6.3-μg/L higher serum 25(OH)D concentration compared with nonusers. Previous GWAS-identified gene regions were not replicated in African Americans, but the nonsynonymous rs7041 SNP in group-specific component (vitamin D binding protein) was close to significance thresholds (P = 0.08), and there was evidence for an interaction between this SNP and use of multivitamin supplements in relation to serum 25(OH)D concentration (P = 0.04). Twenty-three percent (95% CI: 0%, 52%) of the variation in serum 25(OH)D was explained by total genetic variation in a pooled GCTA of 2087 Health ABC Study and MESA African-American participants, but population substructure effects could not be separated from other genetic influences.

CONCLUSIONS

Modifiable dietary and lifestyle predictors of serum 25(OH)D were identified in African Americans. GCTA confirms that a proportion of 25(OH)D variability is attributable to genetic variation, but genomic regions associated with the 25(OH)D phenotype identified in prior GWASs of European Americans were not replicated in the Health ABC Study in African Americans.

Choline inadequacy impairs trophoblast function and vascularization in cultured human placental trophoblasts

Maternal choline intake during gestation may influence placental function and fetal health outcomes. Specifically, we previously showed that supplemental choline reduced placental and maternal circulating concentrations of the anti-angiogenic factor, fms-like tyrosine kinase-1 (sFLT1), in pregnant women as well as sFLT1 production in cultured human trophoblasts. The current study aimed to quantify the effect of choline on a wider array of biomarkers related to trophoblast function and to elucidate possible mechanisms. Immortalized HTR-8/SVneo trophoblasts were cultured in different choline concentrations (8, 13, and 28 µM [control]) for 96-h and markers of angiogenesis, inflammation, apoptosis, and blood vessel formation were examined. Choline insufficiency altered the angiogenic profile, impaired in vitro angiogenesis, increased inflammation, induced apoptosis, increased oxidative stress, and yielded greater levels of protein kinase C (PKC) isoforms δ and ϵ possibly through increases in the PKC activators 1-stearoyl-2-arachidonoyl-sn-glycerol and 1-stearoyl-2-docosahexaenoyl-sn-glycerol. Notably, the addition of a PKC inhibitor normalized angiogenesis and apoptosis, and partially rescued the aberrant gene expression profile. Together these results suggest that choline inadequacy may contribute to placental dysfunction and the development of disorders related to placental insufficiency by activating PKC.

Use and applications of systematic reviews in public health nutrition

Decisions related to a spectrum of nutrition-related public health and clinical concerns must consider many factors and are best informed by evaluating the totality and quality of the evidence. Systematic review (SR) is a structured process to evaluate, compare, and synthesize relevant evidence for the SR-specific question(s). Applications of SR are exemplified here through the discussion of four case studies: research agendas, nutrient reference intakes, dietary guidance, and practice guidelines. Concerns that SR cannot be effectively applied to nutrition evidence because of the lack of an unexposed comparator and the complex homeostasis in nutrition are discussed. Central to understanding the applicability of SR is its flexibility in defining key inclusion criteria and rigorous elements as appropriate for the SR-specific question(s). Through the reduction of bias and random error by explicit, reproducible, comprehensive, and rigorous examination of all of the evidence, SR informs the scientific judgment needed for sound evidence-based public health nutrition.

Key questions in vitamin D research

Despite interest and expanding research on non-bone health outcomes, the evidence remains inconclusive concerning the causal role of vitamin D in the non-bone health outcomes. To improve our understanding of its role, research needs to address five key areas related to vitamin D: 1) its physiology and molecular pathways. 2) its relationship to health outcomes. 3) its exposure-response relationships, 4) its interactions with genotype and other nutrients and 5) its adverse effects. Its metabolism needs to be elucidated including extra-renal activation and catabolism, distribution and mobilization from body pools, kinetics of this distribution, and their regulation during pregnancy and lactation. Rigorous, well-designed randomized clinical trials need to evaluate the causal role of vitamin D in a diverse array of non-bone health and chronic disease outcomes across the life cycle and reproductive states. Critically needed is the determination of the exposure-response, inflection and threshold of serum 25(OH)D concentrations relative to functional and health outcomes. The dose-response relationships of standardized measures of serum 25(OH)D need to be understood in response to low and high doses of total vitamin D with careful consideration of confounding factors including catabolic rates. How do relevant genetic polymorphisms, dietary calcium and phosphate and potentially dietary cholesterol interact with vitamin D exposure on its bioavailability, transport, distribution in body pools, metabolism and action as well as on bone and non-bone health outcomes? The nature and mechanisms of U-shaped risk relationships with adverse health outcomes at higher exposure to vitamin D needs elucidated across the life cycle and reproductive stages.

Vitamin D and adverse pregnancy outcomes: beyond bone health and growth

Concerns exist about adequacy of vitamin D in pregnant women relative to both maternal and fetal adverse health outcomes. Further contributing to these concerns is the prevalence of inadequate and deficient vitamin D status in pregnant women, which ranges from 5 to 84% globally. Although maternal vitamin D metabolism changes during pregnancy, the mechanisms underlying these changes and the role of vitamin D during development are not well understood. Observational evidence links low maternal vitamin D status with an increased risk of non-bone health outcome in the mother (pre-eclampsia, gestational diabetes, obstructed labour and infectious disease), the fetus (gestational duration) and the older offspring (developmental programming of type 1 diabetes, inflammatory and atopic disorders and schizophrenia); but the totality of the evidence is contradictory (except for maternal infectious disease and offspring inflammatory and atopic disorders), lacking causality and, thus, inconclusive. In addition, recent evidence links not only low but also high maternal vitamin D status with increased risk of small-for-gestational age and schizophrenia in the offspring. Rigorous and well-designed randomised clinical trials need to determine whether vitamin D has a causal role in non-bone health outcomes in pregnancy.

IOM committee members respond to Endocrine Society vitamin D guideline

In early 2011, a committee convened by the Institute of Medicine issued a report on the Dietary Reference Intakes for calcium and vitamin D. The Endocrine Society Task Force in July 2011 published a guideline for the evaluation, treatment, and prevention of vitamin D deficiency. Although these reports are intended for different purposes, the disagreements concerning the nature of the available data and the resulting conclusions have caused confusion for clinicians, researchers, and the public. In this commentary, members of the Institute of Medicine committee respond to aspects of The Endocrine Society guideline that are not well supported and in need of reconsideration. These concerns focus on target serum 25-hydroxyvitamin D levels, the definition of vitamin D deficiency, and the question of who constitutes a population at risk vs. the general population.

Vitamin D in pregnancy and lactation in humans

Concerns exist about the adequacy of vitamin D in pregnant and lactating women. This review assesses the evidence that maternal vitamin D status influences maternal, fetal, and breast-fed infant bone health; maternal adverse outcomes (preeclampsia, gestational diabetes, obstructed labor, and infectious disease); fetal adverse outcomes (growth, gestational age, and developmental programming); and infant adverse outcomes. The evidence for all of these outcomes is contradictory (except for maternal infectious disease) and lacking causality; thus, it is inconclusive. The 2011 Dietary Reference Intakes for vitamin D and their implications for assessing vitamin D status are discussed. An estimated 5% to 29% of American pregnant women may have inadequate vitamin D status, with the higher prevalence in African Americans. Little is known about the prevalence of inadequacy in American lactating women. Research needs are also identified, especially the need for rigorous and well-designed randomized clinical trials to determine the role of vitamin D in nonbone health outcomes in pregnancy and lactation.

The 2011 Dietary Reference Intakes for Calcium and Vitamin D: what dietetics practitioners need to know

The Institute of Medicine Committee to Review Dietary Reference Intakes for Calcium and Vitamin D comprehensively reviewed the evidence for both skeletal and nonskeletal health outcomes and concluded that a causal role of calcium and vitamin D in skeletal health provided the necessary basis for the 2011 Estimated Average Requirement (EAR) and Recommended Dietary Allowance (RDA) for ages older than 1 year. For nonskeletal outcomes, including cancer, cardiovascular disease, diabetes, infections, and autoimmune disorders, randomized clinical trials were sparse, and evidence was inconsistent, inconclusive as to causality, and insufficient for Dietary Reference Intake (DRI) development. The EAR and RDA for calcium range from 500 to 1,100 and 700 to 1,300 mg daily, respectively, for ages 1 year and older. For vitamin D (assuming minimal sun exposure), the EAR is 400 IU/day for ages older than 1 year and the RDA is 600 IU/day for ages 1 to 70 years and 800 IU/day for 71 years and older, corresponding to serum 25-hydroxyvitamin D (25OHD) levels of 16 ng/mL (40 nmol/L) for EARs and 20 ng/mL (50 nmol/L) or more for RDAs. Prevalence of vitamin D inadequacy in North America has been overestimated based on serum 25OHD levels corresponding to the EAR and RDA. Higher serum 25OHD levels were not consistently associated with greater benefit, and for some outcomes U-shaped associations with risks at both low and high levels were observed. The Tolerable Upper Intake Level for calcium ranges from 1,000 to 3,000 mg daily, based on calcium excretion or kidney stone formation, and from 1,000 to 4,000 IU daily for vitamin D, based on hypercalcemia adjusted for uncertainty resulting from emerging risk relationships. Urgently needed are evidence-based guidelines to interpret serum 25OHD levels relative to vitamin D status and intervention.

The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know

This article summarizes the new 2011 report on dietary requirements for calcium and vitamin D from the Institute of Medicine (IOM). An IOM Committee charged with determining the population needs for these nutrients in North America conducted a comprehensive review of the evidence for both skeletal and extraskeletal outcomes. The Committee concluded that available scientific evidence supports a key role of calcium and vitamin D in skeletal health, consistent with a cause-and-effect relationship and providing a sound basis for determination of intake requirements. For extraskeletal outcomes, including cancer, cardiovascular disease, diabetes, and autoimmune disorders, the evidence was inconsistent, inconclusive as to causality, and insufficient to inform nutritional requirements. Randomized clinical trial evidence for extraskeletal outcomes was limited and generally uninformative. Based on bone health, Recommended Dietary Allowances (RDAs; covering requirements of ≥97.5% of the population) for calcium range from 700 to 1300 mg/d for life-stage groups at least 1 yr of age. For vitamin D, RDAs of 600 IU/d for ages 1-70 yr and 800 IU/d for ages 71 yr and older, corresponding to a serum 25-hydroxyvitamin D level of at least 20 ng/ml (50 nmol/liter), meet the requirements of at least 97.5% of the population. RDAs for vitamin D were derived based on conditions of minimal sun exposure due to wide variability in vitamin D synthesis from ultraviolet light and the risks of skin cancer. Higher values were not consistently associated with greater benefit, and for some outcomes U-shaped associations were observed, with risks at both low and high levels. The Committee concluded that the prevalence of vitamin D inadequacy in North America has been overestimated. Urgent research and clinical priorities were identified, including reassessment of laboratory ranges for 25-hydroxyvitamin D, to avoid problems of both undertreatment and overtreatment.

NIH consensus development conference statement: Lactose intolerance and health

OBJECTIVE

To provide health care providers, patients, and the general public with a responsible assessment of currently available data on lactose intolerance and health.

PARTICIPANTS

A non-DHHS, nonadvocate 14-member panel representing the fields of internal medicine, pediatrics, pediatric and adult endocrinology, gastroenterology, hepatology, neonatology and perinatology, geriatrics, racial/ethnic disparities, radiology, maternal and fetal nutrition, vitamin and mineral metabolism, nutritional sciences, bone health, preventive medicine, biopsychology, biostatistics, statistical genetics, epidemiology, and a public representative. In addition, 22 experts from pertinent fields presented data to the panel and conference audience.

EVIDENCE

Presentations by experts and a systematic review of the literature prepared by the University of Minnesota Evidence-based Practice Center, through the Agency for Healthcare Research and Quality. Scientific evidence was given precedence over anecdotal experience.

CONFERENCE PROCESS

The panel drafted its statement based on scientific evidence presented in open forum and on published scientific literature. The draft statement was presented on the final day of the conference and circulated to the audience for comment. The panel released a revised statement later that day at http://consensus.nih.gov. This statement is an independent report of the panel and is not a policy statement of the NIH or the Federal Government.

CONCLUSIONS

• Lactose intolerance is a real and important clinical syndrome, but its true prevalence is not known. • The majority of people with lactose malabsorption do not have clinical lactose intolerance. Many individuals who think they are lactose intolerant are not lactose malabsorbers. • Many individuals with real or perceived lactose intolerance avoid dairy and ingest inadequate amounts of calcium and vitamin D, which may predispose them to decreased bone accrual, osteoporosis, and other adverse health outcomes. In most cases, individuals do not need to eliminate dairy consumption completely. • Evidence-based dietary approaches with and without dairy foods and supplementation strategies are needed to ensure appropriate consumption of calcium and other nutrients in lactose-intolerant individuals. • Educational programs and behavioral approaches for individuals and their healthcare providers should be developed and validated to improve the nutrition and symptoms of individuals with lactose intolerance and dairy avoidance.

Summary of roundtable discussion on vitamin D research needs

We summarize the discussions of a roundtable following the conference "Vitamin D and Health in the 21st Century: an Update." The roundtable participants offered additional information on vitamin D research needs from a critical, impartial, and interdisciplinary perspective. Although the group recognized the progress to date, they found that the available evidence on the relation of 25-hydroxyvitamin D, dietary intake, status, functional health, and adverse outcomes has significant limitations because most studies have been short term, have failed to consider important confounders such as baseline vitamin D status and body mass index, and did not study key populations. To meet these data gaps, the roundtable identified several overarching research needs: 1) long-term, high-quality dose-response studies with relevant outcomes, including bone health, other functional outcomes (such as immune function, autoimmune disorders, and chronic disease prevention), and adverse outcomes (such as hypercalcemia and hypercalcuria), especially in understudied population groups such as dark-skinned individuals, infants, adolescents, reproductive-aged women, and pregnant and lactating women; 2) further research to understand the relation of 25-hydroxyvitamin D threshold values to relevant functional outcomes in each life stage and in racial and ethnic groups; 3) further research to understand the metabolic partitioning, fate, and mobilization of key vitamin D metabolites at recommended and greater than recommended intakes to assess the availability of stored vitamin D, relative contributions of endogenously produced and dietary vitamin D, and impact of important confounders (such as body mass index) on vitamin D status; and 4) further research to define the maximal, long-term vitamin D intake to ensure safety for all humans.

Lactation decreases pancreatic lipase mRNA level in the rat

Lactation alters maternal metabolism and increases food intake in rats to support milk production. Pancreatic lipase (PL) is primarily responsible for fat digestion in adults and is regulated by dietary fat. The present research determined the regulation of PL by lactation and dietary fat. In Expt 1, eighteen Sprague–Dawley dams and twelve age-matched virgins (controls) were fed a low-fat diet (LF; 11 % energy as safflower oil) for 7–63 d. At postpartum (day 0), peak lactation (day 15) and post-lactation (day 56) and after 7 d in virgins, the pancreas was removed for mRNA and enzyme analyses. In Expt 2, thirty-six Sprague–Dawley dams were fed LF until day 9 postpartum when dams were divided into three groups of twelve; one continued to be fed LF, one was fed a moderate-fat diet (MF; 40 % energy as safflower oil); and one was fed a high-fat diet (HF; 67 % energy as safflower oil) diet. At peak lactation (day 15) and post-lactation (day 56), the pancreas was removed for mRNA and enzyme analyses. Expt 1 revealed that lactation and post-lactation significantly (P<0·001) decreased PL mRNA (67 % and 76 %, respectively), but only post-lactation decreased PL activity. Increased dietary fat in Expt 2 significantly increased PL mRNA (LF<MF<HF,P<0·001) and PL activity (LF<MF=HF,P<0·02) in both lactation and post-lactation. In summary, lactation and post-lactation decreased PL mRNA significantly even though dietary fat still regulated PL activity and mRNA in lactation and post-lactation.

Pancreatic lipase and its related protein 2 are regulated by dietary polyunsaturated fat during the postnatal development of rats

The developmental gene expression of pancreatic lipase (PL) and its related proteins (PLRP1 and PLRP2) is anticoordinate. It is unknown whether dietary fat regulates the expression of these proteins in the preweanling stage. For determining the regulation of development and diet on PL, PLRP1, and PLRP2 as early as the suckling period, pregnant (Sprague-Dawley) rats consumed from day 15 (d15) of pregnancy through d9 of lactation a purified low (11% of energy) safflower oil diet [low-fat (LF)]. From d9 of lactation, dams and their respective pups were fed LF, medium-fat (MF; 40% of energy), or high-fat (HF; 67% of energy) safflower oil diets to d56. Milk fatty acid content had 15- to 100-fold less C:10 and 2.6- to 3.3-fold more C18:2 in MF and HF groups. Diet (LF < MF = HF; P < 0.002), postnatal development (d15 < d21 < d28 = d56; P < 0.001), and interaction of diet x development significantly affected PL activity starting as early as d15. PL mRNA levels showed a parallel effect of diet (LF < HF = MF; P < 0.013) and development (P < 0.001). Both PLRP1 and PLRP2 mRNA levels were significantly affected by development (P < 0.001) and had an anticoordinate pattern compared with PL expression (d15 > d21 > d28). Reported for the first time is the significant down-regulation of PLRP2 mRNA levels by high polyunsaturated fat in suckling (d15) rats. In conclusion, PL and PLRP2 gene expression is regulated anticoordinately by the amount of dietary polyunsaturated fat starting as early as the preweanling phase of development.

Regulation of pancreatic lipase by dietary medium chain triglycerides in the weanling rat

Pancreatic lipase (PL) and its related protein 1 (PLRP1) are regulated by the amount of dietary fat through an apparent transcriptional mechanism. Regulation of PL and PLRP1 by type of fat (chain length and degree of saturation) is less well understood. The aim of this study was to determine whether medium-chain triglycerides regulate PL and PLRP1. For 7 d, weanling (21-d-old) Sprague Dawley male rats were fed diets low (11% of energy), moderate (40% of energy), or high (67% of energy) in trioctanoate/tridecanoate (MCT) or safflower (low fat only) oils. Food consumption decreased as dietary MCT increased, and the consumption of MCT diets was lower than that of the low-safflower (control) diet. Final body weight was similar among rats fed the low- or moderate-MCT or control diets, but was significantly reduced (17%) in those fed the high-MCT diets. PL activity was significantly elevated 53-60% (p < 0.002) in rats fed low and moderate MCT diets, respectively, compared with that of rats fed high-MCT or control diets. PL and PLRP1 mRNA levels were not significantly different among diets, suggesting that chain length regulates PL and PLRP1 translationally or posttranslationally. The beta-hydroxybutyrate plasma concentration was significantly (p < 0.02) higher (85%) in rats consuming low-MCT diet compared with those of rats fed the control diet. MCT at low levels, but not high levels, increase PL activity without changing its mRNA levels.

Circulating leptin levels in newborn rats: a significant post- natal developmental effect, independent of dietary polyunsaturated fat levels

Leptin expression exhibits developmental and dietary regulation, but it is unknown whether there is an interaction of the regulation by dietary fat and postnatal development. The purpose of this study was to test the effect of different levels of dietary polyunsaturated fat on circulating leptin levels at different post-natal developmental stages. Pregnant (Sprague-Dawley) rats consumed from day 15 of pregnancy through day 9 of lactation a low fat, (11% of energy; LF) polyunsaturated safflower oil diet. From day 9 of lactation, dams and their respective pups were fed low, moderate (40% of energy; MF) or high (67% of energy; HF) polyunsaturated safflower oil diets to full maturation (56 days). Diets were iso-energetic and iso-nitrogenous. Milk fatty acid content reflected the mothers and pups diet, with 15 to 100 fold less C10:0 and 2.6 to 3.3 fold more C18:2 in MF and HF groups compared to LF diet. In newborn rats through post-natal day 56, levels of polyunsaturated fat in mothers' milk and mothers/pups diet had no effect on the levels of circulating leptin. The post-natal development period significantly affected circulating leptin levels (p < 0.001, 15 days = 56 days > 21 days > 28 days). In summary, the developmental postnatal stage regulates leptin levels, independently of the polyunsaturated fat levels in the diet.

Regulation of pancreatic amylase and lipase gene expression by diet and insulin in diabetic rats

Although insulin has been proposed to mediate the dietary regulation of pancreatic amylase, its interaction with diet in the regulation of amylase and lipase is not well understood and was examined in diabetic rats fed diets high in carbohydrate (HC), protein (HP), or fat (HF) and treated with insulin. Diabetes, independent of diet, decreased amylase content (97%; P < 0.0001) and mRNA (90%; P < 0.0001), but insulin only restored amylase content and mRNA to respective dietary control values. Diabetes, independent of diet, also increased lipase mRNA 1.6-fold (P < 0.004) but interacted (P < 0.0003) with diet on lipase content, resulting in opposite effects in HC- (increased 202%) and HF-diabetic rats (decreased 40%). Insulin partially restored lipase content and mRNA to respective dietary control values. Diet, independent of diabetes, regulated amylase content (P < 0.0001) and mRNA (P < 0.0003), which were three- to fourfold greater in HC- than in HF-fed rats, and lipase content (P < 0.001) and mRNA [rat pancreatic lipase 1 (rPL-1), P < 0.04; rPL-3, P < 0.0001], which were 1.8-fold greater in HF- than in HC- or HP-fed rats. Insulin failed to stimulate maximal amylase gene expression in HP- or HF-fed diabetic rats, suggesting that it is necessary, but not sufficient, for this dietary regulation. Differential regulation of lipase activity and mRNA by diet and insulin raises the possibility that lipase gene expression is regulated by a complex interaction of diet and insulin.

Amount and type of dietary fat regulate pancreatic lipase gene expression in rats

Both amount and type of dietary triglycerides regulate pancreatic lipase, but the mechanism is not fully understood. This study investigated the effects of type (safflower oil and lard) and amount [low (50 g/kg diet) or moderate (174 g/kg diet)] of fat on rat pancreatic lipase (rPL) activity and mRNA levels. Polyunsaturated safflower oil resulted in 80% greater lipase activity compared with the saturated lard at moderate levels, whereas safflower oil resulted in 50% lower lipase activity compared with lard at low levels. The rPL-3 mRNA levels were greater in rats fed the moderate safflower oil diet (163%) or the moderate lard diet (212%) than in those fed the respective low fat diets and were 45% greater in those fed safflower oil than in those fed lard. The rPL-1 mRNA levels were greater in rats fed moderate safflower oil (50%) or lard (135%) than in those fed the respective low fat diet, but these levels were not affected by type of fat, in contrast to rPL-3 mRNA levels. The amount of fat independent of its type regulates pancreatic lipase pre-translationally, because increasing dietary saturated or polyunsaturated fat resulted in parallel changes in rPL-3 and rPL-1 mRNA levels. However, type of fat may regulate pancreatic lipase at other levels such as translational or post-translational, because the 212% increase in rPL-3 mRNA in rats fed the moderate lard diet compared with the low lard diet did not result in greater pancreatic lipase activity.

Effects of secretin and caerulein on pancreatic digestive enzymes in cultured rat acinar cells

Caerulein is proposed to regulate the synthesis of pancreatic proteases and amylase. Similarly, secretin is implicated in the regulation of pancreatic lipase synthesis. Evidence of these regulations is predominantly from in vivo studies. We therefore examined the effects of caerulein and secretin directly on acinar cells to eliminate possible interactions with other regulatory factors. Cellular and media enzyme activities and relative synthesis were measured after 24 h of hormonal treatment. Cells were incubated with [14C]-amino acids and then subjected to two-dimensional gel electrophoresis to separate individual acinar proteins for subsequent determination of incorporated radioactivity and relative synthesis. In general, all enzyme activities decreased (33%; p < 0.02) over time in culture and medium enzyme activities increased (370%; p < 0.00001) in all treatment groups. Caerulein further decreased cellular content of all enzymes (p < 0.002) and increased media amylase and lipase activities (p < 0.02). Caerulein, however, significantly increased the relative synthesis of trypsin (28%) and tended to increase that of chymotrypsin (25%; p < 0.06), which supports its proposed role in protease regulation. Secretin, on the other hand, did not significantly affect the cellular or medium activities or the relative synthesis of any pancreatic enzyme evaluated. Therefore, this study does not support the proposed role of secretin in lipase regulation.

Ontogenic differences in the inhibition of gastric acid secretion by epidermal growth factor

Gastric secretions were studied in rats by pyloric ligation in vivo. The effects of epidermal growth factor (EGF) administered s.c. on gastric secretion were evaluated at different stages of development (8, 14, 20 and 30 postnatal days). The rates of fluid, protein and acid outputs were very low in developing rats but increased in maturing rats. The rate of acid output in 8- day-old rats (3.83 +/- 1.16) was not different from that in 14-day-old rats (4.84 +/- 0.99), whereas the rate of acid output in 20-day-old rats was 11-fold greater than that in 14-day-old rats, and it was 21-fold greater in 30-day-old rats. Subcutaneous administration of 30 micrograms/kg b.wt. of EGF significantly suppressed the gastric secretion of fluid, protein and acid in 20- and 30-day-old rats. In 30-day-old rats, acid output was 85% lower at 1 hr after EGF administration and in 20-day-old rats it was 85% lower at 2 hr and 50% lower at 3 hr. Interestingly, EGF had no effect on basal gastric secretions in 8- and 14-day-old rats; EGF also had no effect on the gastric acid output that was stimulated by pentagastrin administration in 14-day-old rats. In 20-day-old rats, inhibitory effects of EGF lasted for 3 hr before gastric secretions rebounded to normal levels, but inhibition lasted for only 1 hr in 30-day-old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of secretin and caerulein on enzymes of cultured pancreatic acinar cells

We examined the effects of secretin (0 to 200 nM) and caerulein (0 to 100 nM) on rat pancreatic acinar cells cultured 0 to 48 h in serum-free medium. The effects of 100 nM secretin with 1 nM caerulein were also studied because secretin may potentiate the effects of caerulein. Cellular and media (secreted) lipase and amylase were analyzed as were cellular DNA and protein content. Cellular lipase and amylase activities significantly decreased (P less than 0.0001) over time in all treatment groups, whereas media amylase and lipase significantly increased (P less than 0.0001). Neither secretin nor caerulein affected cellular lipase or media amylase. However, secretin significantly increased (P less than 0.04) and caerulein tended to increase (P less than 0.08) media lipase in a dose-dependent manner. At 12 h, 10 nM secretin maximally increased media lipase (58%) suggesting that cultured acinar cells remain responsive to secretin in vitro. Caerulein, at all concentrations, significantly decreased (P less than 0.001) cellular amylase but exhibited a dose-dependent effect only at 24 h when 100 nM caerulein maximally decreased cellular amylase (34%). Secretin (100 nM) did not alter these effects of caerulein. These results support the proposed role of caerulein in the regulation of amylase but not a direct role of secretin in the regulation of lipase.

Effects of diet and ketones on rat pancreatic lipase in cultured acinar cells

The activity, synthesis rate and mRNA level of pancreatic lipase increase with dietary fat intake. Ketones, intermediates of lipid metabolism, have been proposed to mediate this change. Therefore, we investigated their direct effect on cultured pancreatic acinar cells and examined their possible interactive effects with glucose and dietary fat. beta-Hydroxybutyrate (0.01 to 2 mmol/L) did not affect lipase activity in cells isolated from rats fed a commercial nonpurified (NP) diet and cultured in high glucose (HG, 27.8 mmol/L) or low glucose (LG, 6.9 mmol/L) medium. The effects of ketones were also examined in acinar cells isolated from rats fed purified high fat (HF, 67% of energy from fat) or low fat (LF, 11% of energy from fat) diet. Cellular lipase was significantly higher in cells from HF-fed rats at both 24 and 48 h (264% and 145% of LF values, respectively; P less than 0.0001). beta-Hydroxybutyrate significantly increased (P less than 0.04) lipase activity in LF cells at 48 h but did not affect lipase activity in HF cells. These studies suggest that ketones may be involved in the regulation of pancreatic lipase in rats fed a LF diet, but their role is complex and interactive with dietary carbohydrate and fat.