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Dietary fiber and growth, iron status and bowel function in children 0-5 years old: a systematic review.
Dierkes, J, Nwaru, BI, Ramel, A, Arnesen, EK, Thorisdottir, B, Lamberg-Allardt, C, Spielau, U, Söderlund, F, Bärebring, L, Åkesson, A
Food & nutrition research. 2023;67
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Emerging evidence shows that high fibre intake has beneficial effects on bowel function, cardiometabolic risk factors and cardiometabolic risk in adults, while the benefits are less clear in children. The aim of this study was to identify, critically appraise and synthesize evidence from studies on the role of high fibre intake on growth and development, iron status and bowel function in small children living in affluent countries. This study was a systematic review of fours studies of which two were randomised controlled trials and the other two were observational studies. Results show that there are no robust associations between high intake of fibre and growth in healthy infants and preschool children. Increased dietary fibre increased stool production in the randomised controlled trials, but higher fibre intake was not associated with constipation in the observational study. Authors conclude that there is a lack of studies on high fibre intake and iron status in well-nourished infants and children. Thus, further studies are needed both to determine desirable levels of fibre intake in small children and to clarify the role of dietary fibre in infancy and childhood for normal bowel function, growth and nutritional status.
Abstract
BACKGROUND While dietary fiber intake is low in many children, the current trend to plant-based diets is associated with higher fiber intake in children raised on these diets. As older reports indicate that diets providing high fiber intake in children 0-5 years may affect growth, iron status and bowel function, we summarized the available evidence in this systematic review. OBJECTIVE To identify, critically appraise, and synthesize evidence on the effect of high fiber intake on growth, iron and bowel function in children 0-5 years, with relevance to the Nordic and Baltic countries. METHODS Following a pre-registered protocol, we searched MEDLINE, EMBASE, Cochrane Central of Controlled Trials, and Scopus for clinical trials and prospective cohort studies published until November 2021. Two reviewers independently screened retrieved literature, extracted relevant data, and performed risk of bias assessment. Outcomes were growth, iron metabolism and bowel function in children 0-5 years. We narratively described findings from studies that met inclusion criteria. RESULTS From 5,644 identified records, five articles met the inclusion criteria. Two RCTs had an overall moderate risk of bias, while the three observational studies had serious risk. Overall, we found no robust association between high intake of dietary fiber and growth. In the RCTs, higher intake of fiber had a positive effect on bowel movements and constipation. No studies on fiber intake and iron status were identified.The certainty of the overall evidence was inconclusive for growth and bowel function, while no assessment was made for iron status. CONCLUSION We found no clear association between high intake of dietary fiber and growth or bowel function in young children living in affluent countries, albeit with only a limited number of studies. There is a lack of studies investigating health effects of high fiber intake in small children.
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Adverse Effects of Excessive Zinc Intake in Infants and Children Aged 0-3 Years: A Systematic Review and Meta-Analysis.
Ceballos-Rasgado, M, Lowe, NM, Mallard, S, Clegg, A, Moran, VH, Harris, C, Montez, J, Xipsiti, M
Advances in nutrition (Bethesda, Md.). 2022;13(6):2488-2518
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The upper limit of a nutrient’s intake has been defined as the maximum intake from food, water, and supplements that is unlikely to pose risk of adverse health effects to most individuals in the general population. The aim of this study was to determine the levels of zinc intake at which adverse effects are observed in children aged 0–3 years. This study is a systematic review and meta-analysis of fifty-eight articles from fifty-five studies. Almost all studies were randomised controlled studies (n=52) and the rest were quasi-experimental studies. Results show: - that zinc supplementation had a significant adverse effect on serum ferritin, plasma/serum copper concentration, serum transferrin receptor, haemoglobin, haematocrit, and the odds of anaemia in ≥1 of the subgroups of pooled data. - a significant reduction of the lactulose:mannitol ratio. - that there weren’t significant effects of zinc supplementation on c-reactive protein, erythrocyte superoxide dismutase [antioxidant enzyme], zinc protoporphyrin [chemical compound], blood cholesterol, or iron deficiency anaemia Authors conclude that the recommended maximum zinc doses might need to be adjusted for children at risk or recovering from iron or copper deficiency. Additionally, the study’s findings may be used to undertake dose–response modelling to estimate tolerable upper intake levels of zinc in children aged 0–3 years.
Abstract
Zinc supplementation reduces morbidity, but evidence suggests that excessive intakes can have negative health consequences. Current guidelines of upper limits (ULs) of zinc intake for young children are extrapolated from adult data. This systematic review (PROSPERO; registration no. CRD42020215187) aimed to determine the levels of zinc intake at which adverse effects are observed in young children. Studies reporting potential adverse effects of zinc intake in children aged 0-3 y were identified (from inception to August 2020) in MEDLINE, Embase, and the Cochrane Library, with no limits on study design. Adverse clinical and physical effects of zinc intake were synthesized narratively, and meta-analyses of biochemical outcomes were conducted. Random effects models were used to generate forest plots to examine the evidence by age category, dose, dose duration, chemical formula of zinc, and zinc compared with placebo. The Joanna Briggs Institute Critical Appraisal Checklist, Cochrane Risk of Bias 2, and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) guideline were employed to assess risk of bias and to appraise the certainty of evidence. Fifty-eight studies assessed possible adverse effects of zinc doses ranging from 3 to 70 mg/d. Data from 39 studies contributed to meta-analyses. Zinc supplementation had an adverse effect on serum ferritin, plasma/serum copper concentration, serum transferrin receptor, hemoglobin, hematocrit, and the odds of anemia in ≥1 of the subgroups investigated. Lactulose:mannitol ratio was improved with zinc supplementation, and no significant effect was observed on C-reactive protein, erythrocyte superoxide dismutase, zinc protoporphyrin, blood cholesterol, and iron deficiency anemia. The certainty of the evidence, as assessed using GRADE, was very low to moderate. Although possible adverse effects of zinc supplementation were observed in some subgroups, it is unclear whether these findings are clinically important. The synthesized data can be used to undertake a dose-response analysis to update current guidelines of ULs of zinc intake for young children.
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Nucleotide supplementation: a randomised double-blind placebo controlled trial of IntestAidIB in people with Irritable Bowel Syndrome [ISRCTN67764449].
Dancey, CP, Attree, EA, Brown, KF
Nutrition journal. 2006;5:16
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Nucleotides are the building blocks of DNA and RNA. Dietary sources of nucleotides are found to varying degrees in many foods – lamb, liver, mushrooms (but not fruit and other vegetables) all are rich in nucleotides. Giving nucleotide supplements to infants has been shown to reduce the incidence and duration of diarrhoea, and animal studies show structural improvements in the intestines when nucleotide supplementation is given. The aim of this study was to test the hypothesis that nucleotide supplements would improve symptoms in people with Irritable Bowel Syndrome (IBS). Thirty-seven people with an IBS diagnosis took part in the study. Participants were asked to rate the severity of their IBS symptoms before and throughout the study period, and psychological measures (anxiety, depression, illness intrusiveness and general health) were also assessed. Participants were assigned to either placebo (56 days) followed by supplement (56 days) or the reverse. The supplement given was IntestAidIB which contained: nucleotides & RNA (concentrated extracts of Saccharomyces cerevisae), hydroxypropyl methylcellulose, FOS (fructo-oligosaccharides), Methionine, Glutamine, Inositol, Lysine, Pantothenic acid (Vitamin B5 as Calcium d-pantothenate), Sodium citrate, Riboflavin (Vitamin B2), Vanillin, Folic acid, and Biotin. The supplement improved the severity of all IBS symptoms, apart from diarrhoea, more than the placebo. Symptom improvement ranged from 4 - 6%. A feeling of incomplete evacuation and abdominal pain showed the most improvement and were statistically significant. The differences between groups for diarrhoea, bloating and flatulence were not significant. Although the improvements in symptoms were consistent, the effects were not strong, and the psychological measures showed no improvement. The authors concluded that dietary nucleotide supplementation improves some of the symptoms of IBS. Further studies need to replicate and extend these results, and clarify the mechanism by which improvements occur.
Abstract
BACKGROUND Dietary nucleotide supplementation has been shown to have important effects on the growth and development of cells which have a rapid turnover such as those in the immune system and the gastrointestinal tract. Work with infants has shown that the incidence and duration of diarrhoea is lower when nucleotide supplementation is given, and animal work shows that villi height and crypt depth in the intestine is increased as a result of dietary nucleotides. Dietary nucleotides may be semi-essential under conditions of ill-health, poor diet or stress. Since people with Irritable Bowel Syndrome tend to fulfil these conditions, we tested the hypothesis that symptoms would be improved with dietary nucleotide supplementation. METHODS Thirty-seven people with a diagnosis of Irritable Bowel gave daily symptom severity ratings for abdominal pain, diarrhoea, urgency to have a bowel movement, incomplete feeling of evacuation after a bowel movement, bloating, flatulence and constipation for 28 days (baseline). They were then assigned to either placebo (56 days) followed by experimental (56 days) or the reverse. There was a four week washout period before crossover. During the placebo and experimental conditions participants took one 500 mg capsule three times a day; in the experimental condition the capsule contained the nutroceutical substances. Symptom severity ratings and psychological measures (anxiety, depression, illness intrusiveness and general health) were obtained and analysed by repeated measures ANOVAs. RESULTS Symptom severity for all symptoms (except constipation) were in the expected direction of baseline>placebo>experimental condition. Symptom improvement was in the range 4 - 6%. A feeling of incomplete evacuation and abdominal pain showed the most improvement. The differences between conditions for diarrhoea, bloating and flatulence were not significant at the p < .05 level. There were no significant differences between the conditions for any of the psychological measures. CONCLUSION Dietary nucleotide supplementation improves some of the symptoms of irritable bowel above baseline and placebo level. As expected, placebo effects were high. Apart from abdominal pain and urgency to have a bowel movement, the improvements, while consistent, are modest, and were not accompanied by improvements in any of the psychological measures. We suggest that the percentage improvement over and above the placebo effect is a physiological effect of the nucleotide supplement on the gut. The mechanisms by which these effects might improve symptoms are discussed.