Pasta and the glycemic index: the secret is in the matrix

A recent study published in Foods (Dodi et al., 2023) clarifies how this structure promotes a high concentration of slowly digestible starch (SDS), positioning pasta as a preferred food for controlling postprandial glycemic response. Such evidence lays the foundation for the use of a specific ‘health claim’ authorized in the European Union, so as to communicate these benefits to consumers on labels and advertising.

Methodology

The researchers (Dodi et al., 2023) employed the Englyst classification system to categorize starch into three distinct fractions:

• resistant starch (resistant starch, RS);

• rapidly digestible starch (rapidly digestible starch, RDS); and

• slowly digestible starch (slowly digestible starch, SDS).

This methodology involves simulated gastrointestinal digestion with measurements taken at 20 minutes and 120 minutes to quantify starch fractions (Englyst et al., 1999). The study examined four pasta formats made from durum wheat – penne, fusilli, spaghetti and cavatelli – along with couscous and bread, all made from identical semolina to eliminate variability of the raw material.

Each pasta sample was cooked according to the instructions on the package in unsalted boiling water, while the bread was prepared using a standardized home baking protocol. The couscous was hydrated with boiling water according to conventional preparation methods. After preparation, the samples were ground to simulate chewing before being subjected to enzymatic digestion with pepsin, pancreatin, and amyloglucosidase under controlled temperature and pH conditions. The researchers then analyzed the glucose release at specific time intervals (Dodi et al., 2023).

Key results on starch digestibility

The results showed marked differences in the distribution of starch fractions among the products. The samples of Pasta contained a content of slowly digestible starch (SDS) significantly higher compared to bread and couscous, where SDS accounted for 45.93–55.80% of the available starch in pasta versus just 11.78% in bread and 2.64% in couscous. Bread, conversely, showed the highest content of rapidly digestible starch (RDS), 33.20 g/100g, followed by couscous with 30.40 g/100g, while pasta samples ranged from 11.54 to 15.50 g/100g.

Among pasta shapes, fusilli and cavatelli showed the highest ratios of slowly digestible starch to available starch (55.80% and 53.91%, respectively), followed by spaghetti (49.39%) and penne (45.93%). These differences likely reflect variations in surface area and structural compactness that affect enzymatic accessibility during digestion. The more compact shapes – fusilli and cavatelli – had reduced surface area for α-amylase action, thus slowing starch hydrolysis (Granfeldt et al., 1991).

Theresistant starch (RS) represented only a minor fraction in all products, ranging from 0.40 to 1.06 g/100g, with bread showing the highest content. This finding aligns with expectations, as cooking processes typically reduce RS content while increasing starch gelatinization and digestibility (Wang & Guo, 2020).

Discussion

The substantial differences in slowly digestible starch (SDS) content between pasta and other wheat-based products can be attributed to distinct manufacturing processes. The pasta production process involves extrusion under pressure, creating a protein-starch matrix compact where gluten forms a continuous network that encapsulates starch granules. This structure persists during cooking, creating a physical barrier that limits α-amylase access and slows starch hydrolysis (Petitot et al., 2009).

The production of Bread is instead based on fermentation and baking, which create a porous structure that facilitates rapid enzymatic degradation. The couscous, although made from durum wheat semolina, is steamed rather than subjected to the kneading and extrusion processes characteristic of pasta production. This results in extensive starch gelatinization without the protective gluten network, making the starch highly accessible to digestive enzymes (Bellocq et al., 2018).

The study results have significant implications for  glycemic control and metabolic health. The European Food Safety Authority (EFSA) has indeed recognized the scientific basis of the health claim related to reduced postprandial glycemic response following the consumption of cereal-based products containing at least 55% carbohydrates in the form of starch, of which at least 40% is slowly digestible starch (SDS). All pasta samples analyzed in the Dodi et al. (2023) study exceeded this threshold and could therefore use, on labels and advertising, the ‘health claim’ authorized following the aforementioned EFSA opinion.

‘Health claim’ authorized in European Union

Regulation (EU) No 432/2012, listing the ‘health claims’ authorized in the European Union, permits the use of the health claim:

• ‘Consumption of products high in slowly digestible starch (SDS) results in a lower post-meal blood glucose concentration rise compared to products low in slowly digestible starch’.

This indication can be used ‘only on foods in which digestible carbohydrates provide at least 60% of the total energy and in which at least 55% of such carbohydrates consist of digestible starch, which in turn consists of at least 40% slowly digestible starch’ (Reg. EU No. 432/2012).

Health implications

The consumption of  foods rich in slowly digestible starch (SDS) induces moderate postprandial glycemic and insulinemic responses, which can reduce stress on glucose homeostatic mechanisms. This controlled glucose release supports sustained energy supply while minimizing metabolic disruptions associated with rapid glycemic excursions. Lower postprandial glycemic peaks correlate with improved insulin sensitivity, enhanced β-cell function, and favorable lipid profiles (Livesey et al., 2019).

The gradual glucose absorption characteristic of SDS consumption stimulates the secretion of incretin hormones, which moderate gastric emptying and promote satiety. These effects may contribute to  weight management and the reduction of energy intake. Recent meta-analyses confirm associations between SDS intake and attenuated glycemic responses, supporting its inclusion in dietary strategies for  diabetes prevention (Wang et al., 2023).

Conclusions and perspectives

The study under review conclusively demonstrates that the pasta production process leads to a substantial increase in  slowly digestible starch content (SDS). All pasta samples analyzed by Dodi and colleagues (2023) contained SDS levels above the 40% threshold associated with reduced glycemic responses, strengthening the position of Pasta as a valuable component of  glycemic management strategies.

The findings challenge preconceptions regarding carbohydrate-rich foods and weight gain, providing scientific evidence supporting pasta consumption within balanced dietary patterns. The structural properties conferred by extrusion and gluten-starch matrix formation are critical determinants of starch digestibility, regardless of raw material composition (Dodi et al., 2023).

Future research should investigate individual variability in  chewing patterns and their impact on starch digestibility, as these factors may contribute to inter-individual variations in glycemic response. Furthermore, examining how pasta consumption patterns integrate with overall dietary quality and their long-term effects on  metabolic health outcomes would provide valuable evidence for public health recommendations.

Dario Dongo

Photo by Klaus Nielsen

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• Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children’s development and health. Consolidated text: 20/08/2025 http://data.europa.eu/eli/reg/2012/432/2025-08-20

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