Deborah L. O’Connor

Effect of a low glycaemic index diet on blood glucose in women with gestational hyperglycaemia

AIM The objectives of this pilot study were to determine the feasibility and effect on glycaemic control of a low-glycaemic-index (GI) diet in women with gestational diabetes or impaired glucose tolerance of pregnancy. METHODS participants, recruited from the Diabetes-in-Pregnancy Clinic of an inner-city teaching hospital serving a predominantly non-Caucasian population, were randomized to a low-GI (n=23) or control (n=24) diet and followed from 28 weeks gestation until delivery. Self-monitored-blood-glucose (SMBG), maternal and infant weight were collected from medical charts. Dietary intakes were assessed using diet records and questionnaires. RESULTS diet GI on control (58, 95% CI: 56,60) was significantly higher than on low-GI (49, 95% CI: 47,51; p=0.001). Glycaemic control improved on both diets, but more postprandial glucose values were within target on low-GI (58.4% of n=1891) than control (48.7% of n=1834; p<0.001). SMBG post-breakfast was directly related to pre-pregnancy BMI in the control, but not the low-GI group (BMI*diet interaction; p=0.021). Participants accepted the study foods and were willing to consume them post-intervention. CONCLUSIONS a low-GI diet was feasible and acceptable in this sample and facilitated control of postprandial glucose. A larger study is needed to determine the effect of a low-GI diet on maternal and infant outcomes.

A Comparison of Micronutrient Inadequacy and Risk of High Micronutrient Intakes among Vitamin and Mineral Supplement Users and Nonusers in Canada

Although supplement use is prevalent in North America, there is little information on how supplements affect the prevalence of nutrient adequacy or risk of intakes greater than the tolerable upper intake level (UL). The objectives of this study were to compare the prevalence of nutrient adequacy and percent of intakes greater than the UL from diet alone between supplement users and nonusers and determine the contribution of supplements to nutrient intakes. Dietary intakes (24-h recall) and supplement use (previous 30 d) from respondents ≥1 y in the Canadian Community Health Survey 2.2 (n = 34,381) were used to estimate the prevalence of nutrient adequacy and intakes greater than the UL. Software for Intake Distribution Evaluation was used to estimate usual intakes. The prevalence of nutrient adequacy from diet alone was not significantly higher among supplement users than nonusers for any nutrient. Based on diet alone, children 1-13 y had a low prevalence of nutrient adequacy (<30%) except for vitamin D and calcium. Among respondents ≥14 y, inadequacies of vitamins A and D, calcium, and magnesium were >30%. For other nutrients, there was a low prevalence of nutrient adequacy. There were no nutrient intakes greater than the UL from diet alone, except zinc in children. When supplements were included, ≥10% of users in some age/sex groups had intakes of vitamins A and C, niacin, folic acid, iron, zinc, and magnesium greater than the UL, reaching >80% for vitamin A and niacin in children. In conclusion, from diet alone, the prevalence of nutrient adequacy was low for most nutrients except for calcium, magnesium, and vitamins A and D. For most nutrients, supplement users were not at greater risk of inadequacy than nonusers; supplement use sometimes led to intakes greater than the UL.

High concentrations of folate and unmetabolized folic acid in a cohort of pregnant Canadian women and umbilical cord blood

BACKGROUND Mandatory fortification, prevalent supplement use, and public health guidelines recommending periconceptional supplementation have increased folic acid intakes in North American pregnant women. However, the effects of increased folic acid intakes during pregnancy on maternal and cord blood folate concentrations have not been well established. OBJECTIVES In this prospective study, we determined maternal and cord blood concentrations of folate and unmetabolized folic acid (UMFA) in a cohort of pregnant Canadian women and their newborns and examined the effect of maternal intakes of folate and folic acid and fetal genetic variants in folate metabolism on folate status. DESIGN Folate and folic acid intakes of 368 Canadian pregnant women were assessed in early (0-16 wk) and late (23-37 wk) pregnancy. Blood concentrations of folate and UMFA were measured with the use of immunoassays and liquid chromatography-mass spectrometry, respectively, in maternal samples in early pregnancy (12-16 wk), at delivery (28-42 wk), and in cord blood. Four fetal genetic variants of the 5,10-methylenetetrahydrofolate reductase (MTHFR) and dihydrofolate reductase (DHFR) genes were assessed for their association with cord blood concentrations of folate and UMFA. RESULTS Geometric mean (95% CI) maternal red blood cell (RBC) folate concentrations were 2417 nmol/L (2362, 2472 nmol/L ) and 2793 nmol/L (2721, 2867 nmol/L ) in early pregnancy and at delivery, respectively. The mean (95% CI) cord RBC folate concentration was 2689 nmol/L (2614, 2765 nmol/L). UMFA was detectable in >90% of maternal and cord plasma samples. Although 3 fetal MTHFR and DHFR genetic variants had no effect, the fetal MTHFR 677TT genotype was associated with significantly lower cord serum (P = 0.03) and higher cord RBC (P = 0.02) folate concentrations than those of the wild type. CONCLUSIONS Notwithstanding differences in assays, maternal and cord RBC folate and plasma UMFA concentrations were higher than previously reported values. Functional ramifications of high folate and UMFA concentrations in maternal and fetal circulation warrant additional investigation because an excess folate status may affect long-term health outcomes of the offspring. This study was registered at www.clinicaltrials.gov as NCT02244684.

Options for basing Dietary Reference Intakes (DRIs) on chronic disease endpoints: report from a joint US-/Canadian-sponsored working group

Dietary Reference Intakes (DRIs) are used in Canada and the United States in planning and assessing diets of apparently healthy individuals and population groups. The approaches used to establish DRIs on the basis of classical nutrient deficiencies and/or toxicities have worked well. However, it has proved to be more challenging to base DRI values on chronic disease endpoints; deviations from the traditional framework were often required, and in some cases, DRI values were not established for intakes that affected chronic disease outcomes despite evidence that supported a relation. The increasing proportions of elderly citizens, the growing prevalence of chronic diseases, and the persistently high prevalence of overweight and obesity, which predispose to chronic disease, highlight the importance of understanding the impact of nutrition on chronic disease prevention and control. A multidisciplinary working group sponsored by the Canadian and US government DRI steering committees met from November 2014 to April 2016 to identify options for addressing key scientific challenges encountered in the use of chronic disease endpoints to establish reference values. The working group focused on 3 key questions: 1) What are the important evidentiary challenges for selecting and using chronic disease endpoints in future DRI reviews, 2) what intake-response models can future DRI committees consider when using chronic disease endpoints, and 3) what are the arguments for and against continuing to include chronic disease endpoints in future DRI reviews? This report outlines the range of options identified by the working group for answering these key questions, as well as the strengths and weaknesses of each option.

Folate is absorbed across the human colon: evidence by using enteric-coated caplets containing 13C-labeled [6S]-5-formyltetrahydrofolate

BACKGROUND Folate intakes that do not meet or greatly exceed requirements may be associated with negative health outcomes. A better understanding of contributors that influence the input side will help establish dietary guidance that ensures health benefits without associated risks. Colonic microbiota produce large quantities of folate, and [(13)C5]5-formyltetrahydrofolate infused during colonoscopy is absorbed. However, it is unclear if significant quantities of folate are absorbed in an intact microbiome. OBJECTIVE We determined whether and how much of a physiologic dose of [(13)C5]5-formyltetrahydrofolate delivered in a pH-sensitive enteric caplet to an intact colonic microbiome is absorbed. DESIGN Healthy adults ingested a specially designed pH-sensitive acrylic copolymer-coated barium sulfate caplet that contained 855 nmol (400 μg) [(13)C5]5-formyltetrahydrofolate. After a washout period ≥ 4 wk, subjects received an intravenous injection of the same compound (214 nmol). Serially collected blood samples before and after each test dose were analyzed by using a microbiological assay and liquid chromatography-tandem mass spectrometry. RESULTS Caplet disintegration in the colon was observed by fluoroscopic imaging for 6 subjects with a mean (± SD) complete disintegration time of 284 ± 155 min. The mean (± SEM) rate of appearance of [(13)C5]5-methyltetrahydrofolate in plasma was 0.33 ± 0.09 (caplet) and 5.8 ± 1.2 (intravenous) nmol/h. Likely because of the significant time in the colon, the mean apparent absorption across the colon was 46%. CONCLUSIONS Folate is absorbed across the colon in humans with an undisturbed microbiome. This finding and previous observations of the size of the colonic depot of folate and its potential for manipulation by diet (eg, dietary fiber, oligosaccharides, and probiotics) suggest that an individuals dietary folate requirement may differ depending on the consumption of dietary constituents that affect the size and composition of their gastrointestinal microbiota. In addition, a systematic investigation of the role of colonic folate on gastrointestinal development and the prevention of colorectal cancer is warranted. This trial was registered at clinicaltrials.gov as NCT00941174.

Fat-Modified Breast Milk Resolves Chylous Pleural Effusion in Infants With Postsurgical Chylothorax but Is Associated With Slow Growth

BACKGROUND Chylothorax occurs in ~3%-5% of infants undergoing cardiac surgery. Standard treatment requires discontinuation of breast milk feeding, due to the abundance of long-chain triglycerides and transition to a medium-chain triglyceride (MCT)-based formula. OBJECTIVE To determine the effectiveness of fat-modified breast milk (MBM) for the treatment of chylothorax compared with MCT formula. MATERIALS AND METHODS Infants diagnosed with chylothorax following surgery for congenital heart disease between January 2008 and December 2009 at The Hospital for Sick Children were eligible for this nonrandomized open-label study. Treatment infants (n = 8) received mothers own milk that had been modified by removing the fat layer via centrifugation and adding MCT, nutrients, and essential fatty acids to provide an estimated 74 kcal/100 mL and 1.4 g/100 mL protein (MBM group). Control infants (n = 8) received an MCT formula (MCT group). The feeding intervention was a minimum of 6 weeks after chest tube removal per The Hospital for Sick Children standard chylothorax treatment protocol. RESULTS Daily volume and duration of chest tube drainage were not different between the MBM and MCT groups. While there was no statistically significant difference in rates of weight gain (g/d) between feeding groups, infants in the MBM group, who tended to be younger, experienced a decline in mean weight (P = .04) and length (P = .01) for age z scores. CONCLUSION Fat-modified breast milk resolved chylothorax; however, strategies to address poor growth need to be developed and evaluated in larger trials prior to widespread clinical adoption of this novel treatment.

Visual Development of Human Milk–Fed Preterm Infants Provided With Extra Energy and Nutrients After Hospital Discharge

BACKGROUND Human milk (HM) is the optimal way to nourish preterm low birth weight (LBW) infants after hospital discharge. However, there are few data on which to assess whether HM alone is sufficient to address hospital-acquired nutrition deficits, and no adequately powered studies have examined this question using neurodevelopment as an outcome. The purpose of this work was to determine whether adding extra energy and nutrients to the feedings of predominantly HM-fed LBW infants early after discharge improves their visual development. Visual development was used in this study as a surrogate marker for neurodevelopment. METHODS At discharge, 39 predominantly HM-fed LBW infants (750-1800 g, 1288 ± 288 g) were randomized to receive human milk alone (control) or around half of the HM received daily mixed with a multinutrient fortifier (intervention) for 12 weeks. Grating acuity (ie, visual acuity) and contrast sensitivity were assessed using sweep visual-evoked potential tests at 4 and 6 months corrected age. RESULTS At 4 and 6 months corrected age, intervention infants demonstrated higher grating acuity compared to those in the control group (intervention: 7.8 ± 1.3 and 9.7 ± 1.2 [cycles/degree] vs control 6.9 ± 1.2 and 8.2 ± 1.3, P = .02). Differences in contrast sensitivity did not reach statistical significance (P = .11). CONCLUSION Adding a multinutrient fortifier to a portion of the expressed breast milk provided to predominantly HM-fed LBW infants early after discharge improves their early visual development. Whether these subtle differences in visual development apply to other aspects of development or longer term neurodevelopment are worthy of future investigation.

How Close Are We to Achieving Energy and Nutrient Goals for Very Low Birth Weight Infants in the First Week

Background: Emerging evidence suggests intakes of protein and energy as early as the first week of life in preterm very low birth weight (VLBW) infants are associated with improved neurodevelopment. In response, many neonatal intensive care units (NICUs) have launched new, more aggressive early feeding guidelines. The aim of this study was to evaluate enteral and parenteral energy and macronutrient intakes during the first postnatal week in VLBW infants admitted to NICUs that have introduced more aggressive early feeding guidelines. Materials and Methods: Estimated energy and macronutrient intakes were prospectively collected from VLBW infants fed exclusively mother’s own milk and/or parenteral nutrition and compared with expert recommendations. Days to reach full enteral feeds (150 mL/kg/d) and discharge anthropometrics were examined. Results: By days 6 and 7, median protein and lipid intakes, respectively, reached recommended values (3.5 and 3.0 g/kg/d). However, by day 8, many infants remained below recommended intakes for protein (34%), lipid (34%), carbohydrate (68%), and energy (71%). Late-onset sepsis was associated with a decreased likelihood of reaching full enteral feeds on any given day (hazard ratio, 0.2; 95% confidence interval, 0.1–0.5; P ⩽ .0009). There was no significant relationship between week 1 nutrient intakes and anthropometrics at discharge. Conclusion: Despite the introduction of more aggressive early feeding guidelines and improved energy and nutrient intakes compared with literature values, many VLBW infants remain below recommended nutrition goals in the first week.

Human donor milk for the vulnerable infant: a Canadian perspective

Breast milk is the normal way to feed infants and is accepted worldwide as the optimal first source of nutrition. Though the majority intend to breastfeed, many mothers of sick, hospitalized newborns, particularly those of very low birth weight, are unable to provide a full volume of milk due to numerous physical and emotional barriers to breastfeeding. This vulnerable population of infants may benefit most from receiving breast milk nutrition and thus pasteurized donor milk should be the first consideration for supplementation when there is an inadequate supply of mother’s own milk. This commentary will briefly review the history of milk banking in Canada, as well as the best available evidence for donor milk use in the very low birth weight population, including available economic analyses, with a view to advocate for its use in these vulnerable infants.

Nutrition Issues During Lactation

Breastfeeding is the gold standard and strongly recommended method of feeding infants. The World Health Organization recommends human milk as the exclusive nutrient source for the first 6 months of life, with introduction of solids at this time, and continued breastfeeding until at least 12 months postpartum. It will come as a surprise to many readers that the energy and nutrient needs of lactating women adhering to these optimal infant feeding guidelines will exceed those of pregnancy. During the first 4–6 months of life, an infant will double its birth weight accumulated during the entire 9 months of pregnancy. The nutrient output via breast milk to support this growth is tremendous. Early postpartum, weight is an issue for many women, as they are anxious to return to their prepregnancy body size. For many, weight management will be difficult given personal circumstances and multiple demands on their time. Given the elevated nutrient requirements of lactation, women will need to plan meals with care to maximum nutrient intake while limiting energy dense foods. The purpose of this chapter is to provide an overview of the energy demands of lactation as well as a select list of nutrients known to be sometimes provided in short supply for reproductive age women in developed countries. The specific nutrients to be examined include calcium, vitamin D, folate, vitamin B12, and iron. As energy balance is a current area of concern for many lactating women, and their health care providers, we will also review the literature in relation to dieting and exercise during lactation. Finally, we will close by talking about long-chain polyunsaturated fatty acids (LC-PUFAs), variability in breast milk content, and the implications of maternal LC-PUFAs supplementation on infant outcomes.