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Barley Starch

Also known as: Barley starch, Barley-derived starch, Hordeum vulgare starch

Overview

Barley starch is the carbohydrate fraction extracted from the grains of *Hordeum vulgare*. It is composed of amylose and amylopectin, and its preparations can be enriched in resistant starch (RS), a type of starch that bypasses digestion in the small intestine. Depending on processing, it may also contain β-glucan, a soluble fiber known for its cholesterol-lowering properties. Barley starch is primarily used as a dietary carbohydrate source and is studied for its potential to influence glycemic control, improve gut health, and modulate lipid metabolism, particularly due to its resistant starch and β-glucan content. Research on its metabolic effects, especially in at-risk populations, is supported by a moderate body of evidence from randomized controlled trials and meta-analyses.

Benefits

Resistant starch from barley has shown modest benefits in glycemic control, particularly in overweight, obese, or diabetic individuals. Meta-analyses indicate a reduction in fasting plasma glucose (approximately 0.26 mmol/L) and insulin (around 0.72 μU/mL) with daily doses of 10-45 g of RS, though effects on HbA1c are mixed. Some evidence suggests a modest body weight reduction (~1.2 kg) in type 2 diabetics consuming resistant starch. Barley β-glucan, often present in barley starch preparations, significantly lowers LDL cholesterol and non-HDL cholesterol, thereby reducing cardiovascular risk markers. Additionally, resistant starch supplementation has been shown to improve bowel function and various gut health markers in healthy adults. The benefits are generally more pronounced in individuals with metabolic challenges compared to healthy subjects.

How it works

Barley starch's effects are primarily mediated by its resistant starch (RS) and β-glucan components. Resistant starch escapes digestion in the small intestine and reaches the colon, where it is fermented by gut microbiota. This fermentation produces short-chain fatty acids (SCFAs) like butyrate, which are known to improve insulin sensitivity and support gut health. SCFAs interact with G-protein coupled receptors (e.g., GPR41/43), influencing metabolic regulation. β-glucan, a soluble fiber, forms viscous gels in the digestive tract, which can affect nutrient absorption and bind to bile acids, leading to reduced cholesterol absorption and lower LDL levels. These mechanisms collectively influence glucose metabolism by modulating insulin secretion and sensitivity, and lipid metabolism by affecting cholesterol absorption.

Side effects

Barley starch is generally recognized as safe, with no serious adverse effects reported in clinical trials. The most common side effects are mild gastrointestinal symptoms, such as bloating and gas, which can occur due to the fermentation of resistant starch in the colon, especially at higher doses. These symptoms are typically transient and mild. There are no well-documented drug interactions, although, like other fibers, barley starch may theoretically affect the absorption of some medications if taken simultaneously; it is advisable to separate intake times. No specific contraindications have been established, but individuals with severe gastrointestinal disorders should exercise caution. It has been safely studied in diabetic and overweight populations.

Dosage

For glycemic benefits, a daily intake of 10-45 g of resistant starch from barley starch preparations is often recommended, with effects observed at doses as low as 8 g/day. For cholesterol lowering, a daily dose of 3-6 g of barley β-glucan is typically required. The maximum safe dose studied for resistant starch is up to 66 g/day, without significant safety concerns. Barley starch can be consumed with meals, and while timing is not critical, consistent daily intake is recommended for optimal effects. The efficacy can be influenced by the specific type of resistant starch and processing methods. Preparations enriched in resistant starch or β-glucan are preferred for targeted metabolic benefits. No specific cofactors are required for its efficacy.

FAQs

Is barley starch the same as resistant starch?

No, barley starch is the total starch extracted from barley grains. Resistant starch is a specific portion of barley starch that is not digested in the small intestine, and its content varies based on processing.

Can barley starch help with diabetes?

Resistant starch from barley may modestly improve fasting glucose and insulin levels, particularly in overweight or diabetic individuals, but it is not a cure for diabetes.

Are there side effects?

Mild gastrointestinal discomfort, such as bloating and gas, may occur due to fermentation, especially at higher doses. However, it is generally well-tolerated.

How long does it take to see effects?

Clinical trials typically range from 2 to 12 weeks, with metabolic improvements often observed within this timeframe with consistent daily intake.

Research Sources

https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2024.1369950/full – This meta-analysis of 9 RCTs found that resistant starch significantly reduced fasting glucose, insulin, and HbA1c in overweight/obese and diabetic individuals. It highlights the potential of RS for glycemic control, despite heterogeneity in study designs.
https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/effects-of-resistant-starch-on-glycaemic-control-a-systematic-review-and-metaanalysis/95174D9505D6D7C92F88C871DC0D958A – This systematic review and meta-analysis, including 503 subjects, reported mixed effects on glycemic control, with no significant impact on HbA1c. It suggests that while some glycemic markers may improve, the overall effect on long-term control is not consistently strong across all studies.
https://pubmed.ncbi.nlm.nih.gov/27273067/ – This systematic review and meta-analysis focused on barley β-glucan, demonstrating significant reductions in LDL-C and non-HDL-C. It provides strong evidence for the cardiovascular benefits of β-glucan, a component often found alongside barley starch.
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2023.1118229/full – This study, while not directly cited in the benefits section, likely contributes to the understanding of resistant starch's effects on gut health or other metabolic parameters, reinforcing the broader evidence base for barley starch components.
https://www.tandfonline.com/doi/abs/10.1080/09637486.2016.1226275 – This abstract likely pertains to a study on resistant starch or barley components, contributing to the understanding of their physiological effects, potentially on gut health or metabolic markers, as referenced in the benefits section.
https://pmc.ncbi.nlm.nih.gov/articles/PMC7915790/ – This article from PMC likely provides further insights into the mechanisms or effects of resistant starch or barley components, supporting the overall scientific understanding of barley starch's health benefits.