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

Brazil nuts: an effective way to improve selenium status.

Christine D. Thomson, Alexandra Chisholm, Sarah K. McLachlan, Jennifer M. Campbell

Background: Brazil nuts provide a rich natural source of selenium, yet no studies have investigated the bioavailability of selenium in humans.

Objective: We investigated the efficacy of Brazil nuts in increasing selenium status in comparison with selenomethionine.

Design: A randomized controlled trial was conducted with 59 New Zealand adults. Participants consumed 2 Brazil nuts thought to provide {approx}100 µg Se, 100 µg Se as selenomethionine, or placebo daily for 12 wk. Actual intake from nuts averaged 53 µg Se/d (possible range: 20–84 µg Se). Plasma selenium and plasma and whole blood glutathione peroxidase (GPx) activities were measured at baseline and at 2, 4, 8, and 12 wk, and effects of treatments were compared.

Results: Plasma selenium increased by 64.2%, 61.0%, and 7.6%; plasma GPx by 8.3%, 3.4%, and –1.2%; and whole blood GPx by 13.2%, 5.3%, and 1.9% in the Brazil nut, selenomethionine, and placebo groups, respectively. Change over time at 12 wk in plasma selenium (P < 0.0001 for both groups) and plasma GPx activity in the Brazil nut (P < 0.001) and selenomethionine (P = 0.014) groups differed significantly from the placebo group but not from each other. The change in whole blood GPx activity was greater in the Brazil nut group than in the placebo (P = 0.002) and selenomethionine (P = 0.032) groups.

Conclusion: Consumption of 2 Brazil nuts daily is as effective for increasing selenium status and enhancing GPx activity as 100 µg Se as selenomethionine. Inclusion of this high-selenium food in the diet could avoid the need for fortification or supplements to improve the selenium status of New Zealanders.

Source: Am J Clin Nutr, February 2008;87(2):379-84.

Favorable effects of berry consumption on platelet function, blood pressure, and HDL cholesterol.

Iris Erlund, Raika Koli, Georg Alfthan, et al.

Background: Berries are a particularly rich source of polyphenols. They also contain other bioactive substances, such as vitamin C. Previous studies indicated that the consumption of polyphenol-rich foods (e.g., cocoa, tea, and red wine) may induce beneficial changes in pathways related to cardiovascular health. Whether the consumption of berries has similar effects is unknown.

Objective: We aimed to investigate the effects of berry consumption on hemostatic function, serum lipids, and blood pressure (BP).

Design: Middle-aged unmedicated subjects (n = 72) with cardiovascular risk factors consumed moderate amounts of berry or control products for 8 wk in a single-blind, randomized, placebo-controlled intervention trial.

Results: Berry consumption inhibited platelet function as measured with a platelet function analyzer (using collagen and ADP as platelet activator) [changes: 11% and –1.4% in the berry and control groups, respectively; P = 0.018, analysis of covariance (ANCOVA)]. Plasma biomarkers of platelet activation, coagulation, and fibrinolysis did not change during the intervention. Serum HDL-cholesterol concentrations increased significantly more (P = 0.006, ANCOVA) in the berry than in the control group (5.2% and 0.6%, respectively), but total cholesterol and triacylglycerol remained unchanged. Systolic BP decreased significantly (P = 0.050, ANCOVA); the decrease mostly occurred in subjects with high baseline BP (7.3 mm Hg in highest tertile; P = 0.024, ANCOVA). Polyphenol and vitamin C concentrations in plasma increased, whereas other nutritional biomarkers (i.e., folate, tocopherols, sodium, and potassium) were unaffected.

Conclusion: The consumption of moderate amounts of berries resulted in favorable changes in platelet function, HDL cholesterol, and BP. The results indicate that regular consumption of berries may play a role in the prevention of cardiovascular disease.

Source: Am J Clin Nutr, February 2008;87(2):323-31.

Accuracy of perceptions of overweight and relation to self-care behaviors among adolescents with type 2 diabetes and their parents.

AC Skinner, M Weinberger, S Mulvaney, et al.

Objective: To examine how adolescents with type 2 diabetes and their parents/primary caregivers perceive the adolescents' weight and the relationship of those perceptions to diet and exercise behaviors and perceived barriers to healthy behaviors.

Research and Design Methods: Interviews were conducted with adolescents and their parents about perceptions of the adolescents' weight, diet, and exercise behaviors, as well as barriers to engaging in healthy diet and exercise behaviors. Interviews were linked with clinic records to provide BMI.

Results: A total of 104 parent-adolescent dyads participated. Parents and adolescents typically perceived the adolescents' weight as less severe than it actually was. For parents and adolescents, underestimating the adolescents ' weight was associated with poorer diet behaviors and more perceived barriers to following healthy diet or exercise behaviors.

Conclusions: Addressing misperceptions of weight by adolescents and their parents may be an important first step to improving weight in these patients.

Source: Diabetes Care. February 2008;31(2):227-9.

Lupus erythematosus and herbal medicine.

Eric Yarnell, Kathy Abascal

Numerous herbal medicines show promise for helping people with systemic lupus erythematosus as well as discoid lupus. Herbs that can both suppress and enhance various aspects of the immune system, known as immunomodulators, are particularly interesting in these settings. Trametes versicolor (cloud mushroom, yun zhi), Cordyceps sinensis (cordyceps, duong chong xiao cao), Ganoderma lucidum (reishi, ling zhi), Centella asiatica (gotu kola), and Urtica dioica (nettles) have all been investigated as immunomodulators in relation to lupus. Tripterygium wilfordii (lei gong teng, thundergod vine) is the best-studied of the herbs that suppress the immune system and thereby relieve symptoms of lupus. Artemisia annua and Artemisia apiacea (sweet Annie, qing hao) are also being studied in this regard, as is Nelumbo nucifera (lotus). Additionally, phytoestrogens such as coumestrol may be valuable in treating lupus, though D-canavanine-containing seeds or sprouts of Medicago sativa (alfalfa) should be avoided. Linum usitatissimum (flax) seeds, as well as immunomodulators and thundergod vine, have all shown promise in patients with lupus nephritis.

Source: Alternative and Complementary Therapies. Feb. 1, 2008;14(1):9-12.

A pilot study of Rhodiola rosea for generalized anxiety disorder (GAD).

Alexander Bystritsky, Lauren Kerwin, Jamie D. Feusner

Background: Rhodiola rosea is an herbal supplement that many in the general population in Russia and elsewhere in the world have used for decades to alleviate everyday anxiety, depression, and insomnia. Whether R. rosea is effective in reducing similar symptoms in clinical samples is unknown. The goal of this pilot study was to evaluate whether R. rosea is effective in reducing symptoms of generalized anxiety disorder (GAD).

Method: Ten (10) participants with a DSM-IV diagnosis of GAD, recruited from the UCLA Anxiety Disorders Program and between the ages of 34 and 55, were enrolled in this study from November 2005 to May 2006. Participants received a total daily dose of 340 mg of R. rosea extract for 10 weeks. Assessments included the Hamilton Anxiety Rating Scale (HARS), the Four-Dimensional Anxiety and Depression Scale, and the Clinical Global Impressions of Severity/Improvement Scale.

Results: Individuals treated with R. rosea showed significant decreases in mean HARS scores at endpoint (t = 3.27, p = 0.01). Adverse events were generally mild or moderate in severity, the most common being dizziness and dry mouth.

Conclusions: Significant improvement in GAD symptoms was found with R. rosea, with a reduction in HARS scores similar to that found in clinical trials. These preliminary findings warrant further exploration of treatment with R. rosea in clinical samples.

Source: Journal of Alternative and Complementary Medicine. March 1, 2008,14(2):175-80.

Stress management versus lifestyle modification on systolic hypertension and medication elimination: a randomized trial.

Jeffery A. Dusek, Patricia L. Hibberd, Beverly Buczynski, et al.

Isolated systolic hypertension is common in the elderly, but decreasing systolic blood pressure (SBP) without lowering diastolic blood pressure (DBP) remains a therapeutic challenge. Although stress management training, in particular eliciting the relaxation response, reduces essential hypertension its efficacy in treating isolated systolic hypertension has not been evaluated. We conducted a double-blind, randomized trial comparing 8 weeks of stress management, specifically relaxation response training (61 patients), versus lifestyle modification (control, 61 patients). Inclusion criteria were ≥55 years, SBP 140–159 mm Hg, DBP <90 mm Hg, and at least two antihypertensive medications. The primary outcome measure was change in SBP after 8 weeks. Patients who achieved SBP <140 mm Hg and ≥5 mm Hg reduction in SBP were eligible for 8 additional weeks of training with supervised medication elimination. SBP decreased 9.4 (standard deviation [SD] 11.4) and 8.8 (SD 13.0) mm Hg in relaxation response and control groups, respectively (both ps < 0.0001) without group difference (p = 0.75). DBP decreased 1.5 (SD 6.2) and 2.4 (SD 6.9) mm Hg (p = 0.05 and 0.01, respectively) without group difference (p = 0.48). Forty-four (44) in the relaxation response group and 36 in the control group were eligible for supervised antihypertensive medication elimination. After controlling for differences in characteristics at the start of medication elimination, patients in the relaxation response group were more likely to successfully eliminate an antihypertensive medication (odds ratio 4.3, 95% confidence interval 1.2–15.9, p = 0.03). Although both groups had similar reductions in SBP, significantly more participants in the relaxation response group eliminated an antihypertensive medication while maintaining adequate blood pressure control.

Source: Journal of Alternative and Complementary Medicine. March 1, 2008,14(2):129-38.

Asymmetric weight gain and loss from increasing and decreasing exercise.

PT Williams

Purpose: Although increases and decreases in physical activity are known to cause weight loss and weight gain, respectively, it is not known whether the magnitudes of these changes in weight are equal. Unequal (asymmetric) weight changes could contribute to overall weight gain or loss among individuals with seasonal or irregular activity.

Methods: Changes in adiposity were compared with the running distances at baseline and follow-up in men and women whose reported exercise increased (N = 4632 and 1953, respectively) or decreased (17,280 and 5970, respectively) during 7.7 yr of follow-up.

Results: Per km.wk(-1) decreases in running distance caused more than four times greater weight gain between 0 and 8 km/wk(-1) (slope +/- SE, males: -0.068 +/- 0.005 kg/m(-2); females: -0.080 +/- 0.01 kg/m(-2)) than between 32 and 48 km/wk(-1) (-0.017 +/- 0.002 and -0.010 +/- 0.005 kg/m(-2), respectively). In contrast, increases in running distance produced the smallest weight losses between 0 and 8 km/wk(-1) and statistically significant weight loss only above 16 km/wk(-1). Above 32 km/wk(-1) (30 kcal/kg(-1)) in men and 16 km/wk(-1) (15 kcal/kg(-1)) in women, weight loss from increasing exercise was equal to or greater than weight gained from decreasing exercise; otherwise, weight gain exceeded weight loss.

Conclusion: Weight gained because of reductions in weekly exercise below 30 kcal/kg(-1) in men and 15 kcal/kg(-1) in women may not be reversed by resuming prior activity. Current IOM guidelines (i.e., maintain total energy expenditure at 160% of basal) agree with the men's exercise threshold for symmetric weight change with changing exercise levels. Asymmetric weight changes below this threshold may contribute to weight gain among less-active subjects.

Source: Med Sci Sports Exerc. February 2008;40(2):296-302.

Nested case-control study of occupational physical activity and prostate cancer among workers using a job exposure matrix.

A Krishnadasan, N Kennedy, Y Zhao, et al.

Objective: We conducted a nested case-control study of 362 cases diagnosed between 1 January 1988 and 31 December 1999, and 1,805 matched controls to examine the association between occupational physical activity and prostate-cancer incidence among workers at a nuclear and rocket engine-testing facility in Southern California.

Methods: We obtained cancer incidence data from the California Cancer Registry and seven other state cancer registries. Data from company records were used to construct a job exposure matrix (JEM) for occupational physical activity during employment. Conditional logistic regression was used to estimate associations.

Results: With adjustment for occupational confounders, including socioeconomic status and trichloroethylene (TCE) exposure, high activity levels at work were inversely associated with prostate-cancer incidence among aerospace workers (odds ratio [OR] = 0.55; 95% CI = 0.32-0.95), but not among radiation workers (OR = 0.95; 95% CI = 0.43-2.1).

Conclusions: Our results suggest that adult men who are more continually active at work may have a decreased risk of prostate cancer.

Source: Cancer Causes Control. February 2008;19(1):107-14.