How Processing Methods Affect Olive Health Benefits and Nutrient Content

Jim Crocker
6th July, 2024

How Processing Methods Affect Olive Health Benefits and Nutrient Content

Olive (Olea europaea)

Photo adapted from: Rafael Medina / CC BY (Source)

Key Findings

  • The study from Kagawa University focused on the alpha-glucosidase inhibitory effects of various table olives to manage post-meal blood sugar levels
  • Natural green olives showed double to triple the enzyme inhibitory activity compared to Shinzuke olives, indicating higher effectiveness
  • Natural green olives retain more beneficial phytochemicals, making them a promising functional food for managing postprandial glycemia in type 2 diabetes
Type 2 diabetes mellitus is a widespread metabolic disorder characterized by high levels of glucose in the blood, known as hyperglycemia. A common strategy to manage this condition involves inhibiting alpha-glucosidases, enzymes in the digestive tract that break down carbohydrates into glucose. While synthetic drugs like acarbose are effective alpha-glucosidase inhibitors, they often come with gastrointestinal side effects. This has led researchers to explore natural alternatives, particularly from plant sources, which may offer fewer side effects[2]. A recent study conducted by Kagawa University evaluated the alpha-glucosidase inhibitory effects of various table olives, focusing on their potential as a functional food for managing postprandial glycemia (the rise in blood sugar following a meal)[1]. The study compared Shinzuke olives, a common trade preparation in Japan, with natural green olives and other commercially available table olives. Shinzuke olives are alkali-treated and non-fermented, whereas natural green olives are debittered by brining, a process that may help retain more phytochemicals. Phytochemicals are bioactive compounds found in plants that have various health benefits. Previous research has shown that certain flavonoids, a class of phytochemicals, can inhibit enzymes involved in carbohydrate digestion and suppress intestinal glucose absorption[3]. Additionally, unprocessed olives are known to be rich sources of phenolic antioxidants like hydroxytyrosol, tyrosol, and luteolin, which have important biological properties[4]. In this study, eight types of table olives were tested for their ability to inhibit human intestinal alpha-glucosidase. The results showed significant differences between the types of olives. Shinzuke Mission olives were the least effective, with an IC50 value of 0.710 ± 0.058 mg/mL, indicating a lower inhibitory capacity. In contrast, natural green olives exhibited double to triple the inhibitory activity of Shinzuke olives and operated via a non-competitive mechanism. This means that natural green olives inhibit the enzyme by binding to a site other than the active site, thereby altering the enzyme's function without directly competing with the substrate. The study's findings align with earlier research that identified various natural sources of alpha-glucosidase inhibitors. For instance, certain flavonols like quercetagetin and galangin have been shown to inhibit alpha-glucosidases effectively, although they are generally less potent than synthetic drugs like acarbose[3]. Similarly, compounds found in the fruiting body of Ganoderma lucidum have demonstrated strong alpha-glucosidase inhibitory activity[5]. By retaining more phytochemicals, natural table olives offer a promising alternative for the management of postprandial glycemia. The higher concentration of beneficial phytochemicals in natural olives compared to Shinzuke and other treated olives enhances their potential as functional foods. This study not only underscores the importance of the type of olive preparation but also highlights the broader potential of natural products in managing type 2 diabetes. In conclusion, the research from Kagawa University provides valuable insights into the alpha-glucosidase inhibitory effects of different types of table olives. Natural green olives, in particular, show significant promise as a functional food for managing postprandial glycemia, thanks to their higher retention of phytochemicals and effective inhibition of alpha-glucosidase. This aligns with previous findings on the benefits of natural alpha-glucosidase inhibitors and opens new avenues for dietary management of type 2 diabetes.

FruitsHealthBiochem

References

Main Study

1) Human α-glucosidase inhibition and phytochemical profile of natural and shinzuke treated olives: implications from the processing method

Published 5th July, 2024

https://doi.org/10.1186/s43014-024-00227-7

Related Studies

2) Alpha Glucosidase Inhibitory Activities of Plants with Focus on Common Vegetables.

https://doi.org/10.3390/plants9010002

3) Flavonoids as Human Intestinal α-Glucosidase Inhibitors.

https://doi.org/10.3390/foods10081939

4) Biophenols in table olives.

Journal: Journal of agricultural and food chemistry, Issue: Vol 50, Issue 13, Jun 2002

5) Ganoderol B: a potent α-glucosidase inhibitor isolated from the fruiting body of Ganoderma lucidum.

https://doi.org/10.1016/j.phymed.2011.03.011


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