naturopathydigest.com -- Critical Research

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Critical Research

Critical Research is a regular feature in Naturopathy Digest. Each month, we provide abstracts from studies published in the top peer-reviewed journals; each abstract includes the complete citation and an online link to the journal. Whenever possible, this link directs you to a page where you can order the full text of the study, if desired.

This Month's Featured Abstract

Salt intake is related to soft drink consumption in children and adolescents: a link to obesity?

FJ He, NM Marrero, GA MacGregor

Dietary salt is a major determinant of fluid intake in adults; however, little is known about this relationship in children. Sugar-sweetened soft drink consumption is related to childhood obesity, but it is unclear whether there is a link between salt and sugar-sweetened soft drink consumption. We analyzed the data of a cross-sectional study, the National Diet and Nutrition Survey for young people in Great Britain. Salt intake and fluid intake were assessed in 1688 participants aged 4 to 18 years, using a 7-day dietary record. There was a significant association between salt intake and total fluid, as well as sugar-sweetened soft drink consumption (P<0.001), after adjusting for potential confounding factors. A difference of 1 g/d in salt intake was associated with a difference of 100 and 27 g/d in total fluid and sugar-sweetened soft drink consumption, respectively. These results, in conjunction with other evidence, particularly that from experimental studies where only salt intake was changed, demonstrate that salt is a major determinant of fluid and sugar-sweetened soft drink consumption during childhood. If salt intake in children in the United Kingdom was reduced by half (mean decrease: 3 g/d), there would be an average reduction of approximately 2.3 sugar-sweetened soft drinks per week per child. A reduction in salt intake could, therefore, play a role in helping to reduce childhood obesity through its effect on sugar-sweetened soft drink consumption. This would have a beneficial effect on preventing cardiovascular disease independent of and additive to the effect of salt reduction on blood pressure.

Source: Hypertension. 2008 March;51(3):629-34.

Acute blood pressure lowering, vasoprotective, and antiplatelet properties of dietary nitrate via bioconversion to nitrite.

AJ Webb, N Patel, S Loukogeorgakis, et al.

Diets rich in fruits and vegetables reduce blood pressure (BP) and the risk of adverse cardiovascular events. However, the mechanisms of this effect have not been elucidated. Certain vegetables possess a high nitrate content, and we hypothesized that this might represent a source of vasoprotective nitric oxide via bio-activation. In healthy volunteers, approximately 3 hours after ingestion of a dietary nitrate load (beetroot juice 500 mL), BP was substantially reduced (Delta(max) -10.4/8 mm Hg); an effect that correlated with peak increases in plasma nitrite concentration. The dietary nitrate load also prevented endothelial dysfunction induced by an acute ischemic insult in the human forearm and significantly attenuated ex vivo platelet aggregation in response to collagen and ADP. Interruption of the enterosalivary conversion of nitrate to nitrite (facilitated by bacterial anaerobes situated on the surface of the tongue) prevented the rise in plasma nitrite, blocked the decrease in BP, and abolished the inhibitory effects on platelet aggregation, confirming that these vasoprotective effects were attributable to the activity of nitrite converted from the ingested nitrate. These findings suggest that dietary nitrate underlies the beneficial effects of a vegetable-rich diet and highlights the potential of a "natural" low cost approach for the treatment of cardiovascular disease.

Source: Hypertension. March 2008;51(3):617-9.

Breakfast eating and weight change in a 5-year prospective analysis of adolescents: Project EAT (Eating Among Teens).

MT Timlin, MA Pereira, M Story, et al.

Objective: Breakfast-eating frequency declines through adolescence and has been inversely associated with body weight in cross-sectional studies, with few prospective studies on this topic. This study was conducted to examine the association between breakfast frequency and 5-year body weight change in 2216 adolescents.

Patients and Methods: Project EAT (Eating Among Teens) was a 5-year longitudinal study of eating patterns and weight concerns among adolescents. Surveys were completed in 1998-1999 (time 1) and 2003-2004 (time 2). Multivariable linear regression was used to examine the association between breakfast frequency and change in BMI, with adjustment for age, socioeconomic status, race, physical activity, time 1 BMI and breakfast category, and time 1 dietary and weight-related variables.

Results: At time 1, frequency of breakfast was directly associated with intake of carbohydrate and fiber, socioeconomic status, white race, and physical activity and inversely associated with smoking and alcohol consumption and dieting and weight-control behaviors. In cross-sectional analyses at times 1 and 2, inverse associations between breakfast frequency and BMI remained largely independent of all of the confounding and dietary factors. Weight-related factors (concerns, behaviors, and pressures) explained little of the breakfast-BMI association. In prospective analyses, frequency of breakfast was inversely associated with BMI in a dose-response manner. Further adjustment for confounding and dietary factors did not seem to explain the association, but adjustment for weight-related variables seemed to partly explain this finding.

Conclusions: Although experimental studies are needed to verify whether the association between breakfast and body weight is of a causal nature, our findings support the importance of promoting regular breakfast consumption among adolescents. Future studies should further examine the role of breakfast habits among youth who are particularly concerned about their weight.

Source: Pediatrics. March 2008;121(3):e638-45.

Curcumin prevents and reverses murine cardiac hypertrophy.

HL Li, C Liu, G de Couto, et al.

Chromatin remodeling, particularly histone acetylation, plays a critical role in the progression of pathological cardiac hypertrophy and heart failure. We hypothesized that curcumin, a natural polyphenolic compound abundant in the spice turmeric and a known suppressor of histone acetylation, would suppress cardiac hypertrophy through the disruption of p300 histone acetyltransferase-dependent (p300-HAT-dependent) transcriptional activation. We tested this hypothesis using primary cultured rat cardiac myocytes and fibroblasts as well as two well-established mouse models of cardiac hypertrophy. Curcumin blocked phenylephrin-induced (PE-induced) cardiac hypertrophy in vitro in a dose-dependent manner. Furthermore, curcumin both prevented and reversed mouse cardiac hypertrophy induced by aortic banding (AB) and PE infusion, as assessed by heart weight/BW and lung weight/BW ratios, echocardiographic parameters, and gene expression of hypertrophic markers. Further investigation demonstrated that curcumin abrogated histone acetylation, GATA4 acetylation, and DNA-binding activity through blocking p300-HAT activity. Curcumin also blocked AB-induced inflammation and fibrosis through disrupting p300-HAT-dependent signaling pathways. Our results indicate that curcumin has the potential to protect against cardiac hypertrophy, inflammation, and fibrosis through suppression of p300-HAT activity and downstream GATA4, NF-kappaB, and TGF-beta-Smad signaling pathways.

Source: J Clin Invest. March 3, 2008;118(3):879-93.

A randomized trial of the effects of reducing television viewing and computer use on body mass index in young children.

LH Epstein, JN Roemmich, JL Robinson, et al.

Objective: To assess the effects of reducing television viewing and computer use on children's body mass index (BMI) as a risk factor for the development of overweight in young children.

Design: Randomized controlled clinical trial.

Setting: University children's hospital.

Participants: Seventy children aged 4 to 7 years whose BMI was at or above the 75th BMI percentile for age and sex.

Interventions: Children were randomized to an intervention to reduce their television viewing and computer use by 50% vs. a monitoring control group that did not reduce television viewing or computer use.

Main Outcome Measures: Age- and sex-standardized BMI (zBMI), television viewing, energy intake, and physical activity were monitored every 6 months during 2 years. RESULTS: Children randomized to the intervention group showed greater reductions in targeted sedentary behavior (P < .001), zBMI (P < .05), and energy intake (P < .05) compared with the monitoring control group. Socioeconomic status moderated zBMI change (P = .01), with the experimental intervention working better among families of low socioeconomic status. Changes in targeted sedentary behavior mediated changes in zBMI (P < .05). The change in television viewing was related to the change in energy intake (P < .001) but not to the change in physical activity (P =.37).

Conclusions: Reducing television viewing and computer use may have an important role in preventing obesity and in lowering BMI in young children, and these changes may be related more to changes in energy intake than to changes in physical activity.

Source: Arch Pediatr Adolesc Med. March 2008;162(3):239-45.

Team sports for overweight children: the Stanford Sports to Prevent Obesity Randomized Trial (SPORT).

DL Weintraub, EC Tirumalai, KF Haydel, et al.

Objective: To evaluate the feasibility, acceptability, and efficacy of an after-school team sports program for reducing weight gain in low-income overweight children. DESIGN: Six-month, 2-arm, parallel-group, pilot randomized controlled trial.

Setting: Low-income, racial/ethnic minority community.

Participants: Twenty-one children in grades 4 and 5 with a body mass index at or above the 85th percentile.

Interventions: The treatment intervention consisted of an after-school soccer program. The "active placebo" control intervention consisted of an after-school health education program.

Main Outcome Measures: Implementation, acceptability, body mass index, physical activity measured using accelerometers, reported television and other screen time, self-esteem, depressive symptoms, and weight concerns.

Results: All 21 children completed the study. Compared with children receiving health education, children in the soccer group had significant decreases in body mass index z scores at 3 and 6 months and significant increases in total daily, moderate, and vigorous physical activity at 3 months.

Conclusion: An after-school team soccer program for overweight children can be a feasible, acceptable, and efficacious intervention for weight control.

Source: Arch Pediatr Adolesc Med. March 2008;162(3):232-7.

Blood pressure response to transcendental meditation: a meta-analysis.

JW Anderson, C Liu, RJ Kryscio

Background: Prior clinical trials suggest that the Transcendental Meditation technique may decrease blood pressure of normotensive and hypertensive individuals but study-quality issues have been raised. This study was designed to assess effects of Transcendental Meditation on blood pressure using objective quality assessments and meta-analyses.

Methods: PubMed and Cochrane databases through December 2006 and collected publications on Transcendental Meditation were searched. Randomized, controlled trials comparing blood pressure responses to the Transcendental Meditation technique with a control group were evaluated. Primary outcome measures were changes in systolic and diastolic blood pressure after practicing Transcendental Meditation or following control procedures. A specific rating system (0-20 points) was used to evaluate studies and random-effects models were used for meta-analyses.

Results: Nine randomized, controlled trials met eligibility criteria. Study-quality scores ranged from low (score, 7) to high (16) with three studies of high quality (15 or 16) and three of acceptable quality (11 or 12). The random-effects meta-analysis model for systolic and diastolic blood pressure, respectively, indicated that Transcendental Meditation, compared to control, was associated with the following changes: -4.7 mm Hg (95% confidence interval (CI), -7.4 to -1.9 mm Hg) and -3.2 mm Hg (95% CI, -5.4 to -1.3 mm Hg). Subgroup analyses of hypertensive groups and high-quality studies showed similar reductions.

Conclusions: The regular practice of Transcendental Meditation may have the potential to reduce systolic and diastolic blood pressure by approximately 4.7 and 3.2 mm Hg, respectively. These are clinically meaningful changes.
Source: Am J Hypertens. 2008 Mar;21(3):310-6.

Vitamin D supplementation in early childhood and risk of type 1 diabetes: a systematic review and meta-analysis.

CS Zipitis, AK Akobeng

Objectives: To assess whether vitamin D supplementation in infancy reduces risk of type 1 diabetes in later life. DESIGN: Systematic review and meta-analysis.

Data Sources: Medline, Embase, Cinahl, Cochrane Central Register of Controlled Trials and reference lists of retrieved articles.

Main Outcome Measure: Development of type 1 diabetes. Inclusion criteria: Controlled trials and observational studies which had assessed the effect of vitamin D supplementation on risk of developing type 1 diabetes.

Results: Five observational studies met the inclusion criteria; no randomized controlled trials were found. 4 of the 5 included studies were case control studies and the fifth study was a cohort study. Meta-analysis of data from the case control studies showed that the risk of type 1 diabetes was significantly reduced in infants who were supplemented with vitamin D compared to those who were not supplemented (pooled odds ratio 0.71, 95% CI 0.60 to 0.84). The result of the cohort study was in agreement with that of the meta-analysis. There was also some evidence of a dose-response effect, with those using higher amounts of vitamin D being at lower risk of developing type 1 diabetes. Finally, there was a suggestion that the timing of supplementation might also be important for the subsequent development of type 1 diabetes.

Conclusion: Vitamin D supplementation in early childhood may offer protection against the development of type 1 diabetes. The evidence for this is based on observational studies. Adequately powered, randomized controlled trials with long periods of follow-up are needed to establish causality and the best formulation, dose, duration and period of supplementation.

Source: Arch Dis Child. 2008 Mar 13 [Epub ahead of print].

Beneficial effects of a polyunsaturated fatty acid on infant development: evidence from the Inuit of Arctic Quebec.

Jacobson JL, Jacobson SW, Muckle G, et al.

Objectives: To examine the relation of cord plasma docosahexaenoic acid (DHA) concentration to gestation length, birth size, growth, and infant visual acuity, cognitive, and motor development and the effects on growth and development associated with DHA intake from breast-feeding.

Study Design: DHA, other polyunsaturated fatty acids, and 3 environmental contaminants (polychlorinated biphenyls, mercury, and lead) were assessed in cord plasma and maternal plasma and milk in 109 Inuit infants in Arctic Quebec. Multiple regression was used to examine the relation of cord DHA and DHA from breast-feeding on growth and development at 6 and 11 months, after controlling for contaminant exposure and other potential confounders.

Results: Higher cord DHA concentration was associated with longer gestation, better visual acuity and novelty preference on the Fagan Test at 6 months, and better Bayley Scale mental and psychomotor performance at 11 months. By contrast, DHA from breast-feeding was not related to any indicator of cognitive or motor development in this full-term sample.

Conclusions: The association of higher cord DHA concentration with more optimal visual, cognitive, and motor development is consistent with the need for substantial increases in this critically important fatty acid during the third trimester spurt of synaptogenesis in brain and photoreceptor development.

Source: J Pediatr. 2008 Mar;152(3):356-64.