Gerst tegen hoog cholesterol*
Uit een analyse van verschillende studies over gerst en cholesterol blijkt dat gerst inderdaad goed is voor het verlagen van het totaal
cholesterol, het slechte cholesterol (LDL) en triglycerides. Resultaten werden al binnen 4 weken na dagelijkse inname van gerst en gerstproducten bereikt. Het zijn vooral de bioactieve vezels
bètaglucaan die hiervoor verantwoordelijk zijn. 3-5% van gerst bestaat uit deze vezels. Gemiddeld daalden in 4 weken tijd het totaal cholesterol met ruim 13 mg/dl, het LDL met ruim 10 mg/dl
en de triglyderiden met 12 mg/dl.
Dietary Soluble Fiber May Be Beneficial for Adults With and Without Hypercholesterolemia
The routine use of soluble fibers may be indicated in the diets of adult patients with and without hypercholesterolemia, according to the results of a meta-analysis reported in the Annals of Family Medicine.
"Although the antihyperlipidemic effects of oats have been extensively studied, there are fewer barley studies, and findings have shown more apparent inconsistency in cholesterol effects," write Ripple Talati, PharmD, from University of Connecticut School of Pharmacy in Storrs, and colleagues. "Even though several clinical trials have investigated the impact of barley β-glucan on total cholesterol, LDL [low-density lipoprotein] cholesterol, high density lipoprotein (HDL) cholesterol, and triglycerides, a meta-analysis assessing these effects has not been published. We therefore sought to perform a meta-analysis of randomized controlled trials of barley to better characterize its effect on various lipid parameters."
The reviewers performed a systematic search of the literature from the earliest possible date through January 2008. Inclusion criteria for the meta-analysis were randomized controlled trials of barley reporting efficacy data for 1 or more lipid outcome measures. Weighted mean difference and its 95% confidence interval (CI) were determined by a DerSimonian and Laird random-effects model, and statistical heterogeneity was evaluated with the I2 statistic. Publication bias was assessed with visual inspection of funnel plots, Egger's weighted regression statistics, and the trim-and-fill method.
Eight trials evaluating the lipid-reducing effects of barley met inclusion criteria; these were of 4 to 12 weeks' duration and enrolled a total of 391 patients. The use of barley was associated with significant reduction in levels of total cholesterol (weighted mean difference, –13.38 mg/dL; 95% CI, –18.46 to –8.31 mg/dL), LDL cholesterol (weighted mean difference, –10.02 mg/dL; 95% CI, –14.03 to –6.00 mg/dL), and triglycerides (weighted mean difference, –11.83 mg/dL; 95% CI, –20.12 to –3.55 mg/dL). However, there did not appear to be any significant effect on HDL cholesterol levels (P = .07).
"Barley-derived β-glucan appears to beneficially affect total cholesterol, LDL-cholesterol, and triglycerides, but not HDL-cholesterol," the study authors write. "Based upon available data, barley appears to be well tolerated, with flatulence and abdominal discomfort being reported as the most common adverse effects, but there is not adequate power to look for other less common adverse effects."
Limitations of this meta-analysis are inclusion of crossover and parallel studies, potential for publication bias, and inability to evaluate the potential for harms with barley.
"The results of our study support the routine use of soluble fibers in the diets of adult patients with and without hypercholesterolemia," the review authors conclude. "Barley adds another source of soluble fibers, in addition to oats, psyllium, pectin, and guar gum that patients can consume as part of a healthy diet....Health practitioners should feel comfortable recommending barley β-glucan to their patients to help reduce total cholesterol and LDL cholesterol concentrations as recommended by the NCEP guidelines."
The study authors have disclosed no relevant financial relationships.
Ann Fam Med. 2009;7:157-163.
Clinical Context
Dietary fiber plays an important role in lipid lowering. Barley and oats have similar concentrations of soluble fibers called β-glucan (3.5% - 5.9% of the dry matter), but few studies have examined the efficacy of barley fiber for cholesterol lowering, although the US Food and Drug Administration recommends a daily intake of 3 g or more of soluble fiber to reduce the risk for coronary artery disease.
This is a meta-analysis of randomized clinical trials to examine the effect of barley in the short term for improving lipid parameters.
Study Highlights
· The investigators conducted a systematic search of the literature on MEDLINE, EMBASE, CINAHL, Web of Science, the Cochrane Library, and the Natural Medicines Comprehensive Database through January 2008.
· Included in the study were randomized controlled trials of barley, reporting on at least one of the following outcomes: levels of total cholesterol, LDL cholesterol, HDL cholesterol, or triglycerides.
· Both parallel and crossover studies were included, but at least 4 weeks of washout were required for crossover trials, and without the washout, only the parallel data were considered.
· Primary outcomes were mean change in lipid parameter from baseline as a continuous variable by analysis with use of a random-effects model.
· The initial search yielded 22 studies, of which 8 met inclusion criteria.
· All 8 trials reported total cholesterol data, 7 reported LDL cholesterol data, 6 reported triglycerides, and 6 reported HDL cholesterol data.
· 5 studies used a parallel design, 2 used a crossover design with washout, and 1 used a crossover design without washout.
· The median sample size was 30 participants (range, 10 - 155 participants), and median duration was 4 weeks (range, 4 - 12 weeks).
· The dosage of β-glucan was 3 to 10 g/day (median dose, 7 g/day) administered in various forms including pearled barley, barley bran flour, oil extracts in capsules, and gelling agents.
· 2 studies administered barley with dietary modification.
· 3 studies were industry sponsored.
· Consuming barley was associated with significant reductions in levels of total cholesterol, LDL cholesterol, and triglycerides but not HDL cholesterol vs control.
· No statistical heterogeneity was observed among the studies.
· The funnel plots indicated a low likelihood of publication bias.
· When crossover or non–double-blind trials were excluded, the effect on triglyceride levels lost statistical significance.
· The results did not change when a fixed-effects model was used for analysis.
· The magnitude of change in lipids was –13 mg/dL for total cholesterol levels, –10 mg/dL for LDL cholesterol levels, and –12 mg/dL for triglyceride levels.
· There was no significant change in HDL cholesterol levels with barley consumption (P = .07).
· The effect of barley on lipids was more robust when combined with dietary changes.
· The authors concluded that the magnitude of effect on cholesterol levels with barley consumption was sufficient to reduce the risk for a coronary artery disease event by 1%, a clinically significant reduction.
Pearls for Practice
· Consumption of a median dose of 7 g/day of barley for 4 weeks is associated with a reduction in levels of total cholesterol, LDL cholesterol, and triglycerides.
· Consumption of barley for 4 weeks is not associated with a change in HDL cholesterol levels. (Mei
2009)
