Can seaweeds' impact on skeletal muscle inflammation help prevent diabetes?

By Cheryl Tay contact

- Last updated on GMT

Laminaria japonica (LJ) is one of the brown seaweed species said to have anti-diabetic effects. ©Getty Images
Laminaria japonica (LJ) is one of the brown seaweed species said to have anti-diabetic effects. ©Getty Images
Two species of brown seaweed may help prevent type 2 diabetes through their effects on skeletal muscle inflammation, say researchers in South Korea.

Obesity induces chronic low-grade systemic inflammation, and together, obesity and inflammation often lead to insulin resistance in certain insulin-sensitive tissues, such as skeletal muscles, the liver, and adipose tissues, resulting in type 2 diabetes.

Skeletal muscle is vital in maintaining a balanced glucose level, which requires insulin-signalling by the enzyme phosphatidylinositol 3-kinase, and protein kinase B (Akt). At the same time, enzyme AMPK promotes intracellular glucose uptake independently from insulin.

Previous studies have shown that two types of brown seaweed, Laminaria japonica ​(LJ) and Hizikia fusiforme ​(HF), had anti-diabetic effects.

Does seaweed provide skeletal support?

Based on this, researchers at Cheju Halla General Hospital, Jeju National University and Sungshin Women's University conducted a study to explore these effects and their possible mechanisms using both in vitro ​and in vivo​ models.

For the in vitro ​study, they treated murine skeletal muscle cells with either LJ or HF extracts, and compared the results with that of an insulin-treated control group.

They observed that LJ and HF significantly decreased tumour necrosis factor-α (TNF-α), and increased the production of anti-inflammatory myokines interleukin-6 (IL-6) and interleukin-10 (IL-10) in the mice’s skeletal muscle cells.

They added: "Compared to the control group, the percentage of glucose uptake by LJ and HF was 126.76% and 119.24% respectively, which was comparable to the insulin-treated group as a positive control."

For the in vivo ​study, they used muscle tissue from mice that had received a 16-week high-fat diet supplemented with 5% LJ or HF, comparing the results with that of a group fed only a high-fat diet.

They subsequently noted that the mice's muscle tissues markedly enhanced phosphorylation of Akt and AMPK, compared to the group given only a high-fat diet.

Additionally, the treatment group showed improved insulin sensitivity and lowered fasting glucose levels.

The researchers also reported that while both extracts "significantly inhibited α-glucosidase activity in a dose-dependent manner"​, the HF extract was superior in this regard.

Furthermore, both extracts significantly increased glucose uptake, and induced phosphorylation of Akt and AMPK in both the in vitro ​and in vivo​ skeletal muscle models.

The researchers wrote: "Brown seaweeds contain plenty of carbohydrates, essential amino acids, vitamins, and minerals. In particular, their carbohydrates, such as laminarian and alginic acid, are a form of dietary fibre that delays gastric emptying to reduce the glucose and triglycerides in circulation.

"Furthermore, brown seaweeds have been reported to contain various phenolic compounds that have anti-oxidant, anti-inflammatory, and anti-carcinogenic effects.

"Taken together, these findings imply that the brown seaweeds LJ and HF could be useful therapeutic agents to attenuate muscle insulin resistance due to diet-induced obesity and its associated inflammation."

Further examination of extracts

The researchers said the study was limited by several factors. For instance, the physiological condition of the obese, insulin-resistant mice on a high-fat diet could not be completely mimicked in the myotubes' muscle cells.

Additionally, seaweed extract components differ depending on the solvents used — they used water extracts of both seaweeds in the in vitro​ model, and pulverised freeze-dried seaweeds in the in vivo ​model.

They concluded: "LJ and HF have strong potential to positively affect glucose homeostasis by inhibiting α-glucosidase activity, increasing muscle glucose uptake, and activating insulin signalling-related proteins. Furthermore, LJ and HF extracts influence inflammatory cytokine production in skeletal muscle cells.

"Further studies are warranted to narrow down a potential insulin-signalling cascade influenced by LJ and HF extracts."

 

Source: Nutrients

https://doi.org/10.3390/nu10040491

"Anti-Diabetic Effects and Anti-Inflammatory Effects of Laminaria japonica and Hizikia fusiforme in Skeletal Muscle: In Vitro and In Vivo Model"

Authors: Sae-ym Kang, et al.

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