In this blog post, I want to draw your attention to the third installment in this series, specifically focusing on the section within Kenneth G. Collins et al.’s work, “Looking Beyond the Terrestrial: The Potential of Seaweed Derived Bioactives to Treat Non-Communicable Diseases,” which details the crucial area of Polysaccharides and Prebiotics.
The cell walls of seaweed contain mostly polysaccharides that give the plants strength and flexibility while regulating the internal ionic balance and preventing water loss. Seaweed structural polysaccharides, such as agar (red algae) and alginate (brown algae), are complex and therefore resistant to degradation by human digestive enzymes and available for fermentation by the intestinal microflora in the large intestine. They can therefore be considered as a source of dietary fiber. The dietary fiber content of seaweed ranges from 33% to 75%, with the soluble fraction accounting for 50% to 80% of the total dietary fiber content.
In general, seaweed polysaccharides are hydrophilic, often water-soluble, form intra-chain hydrogen bond networks, are hard and stiff, and are ideal for use as thickening agents. Seaweed polysaccharides are also useful as gelling agents, as they facilitate interactions with external ions and inter-chain hydrogen bonds. The composition, chemical structure, physiochemical properties, and biological activity of dietary fiber from seaweed vary significantly from those of terrestrial sources. Considering this, the structural polysaccharides found in brown algae, specifically laminarin and fucoidan, could potentially offer a dietary method for influencing the gut microbiota and/or the body’s immune response.
The definition of prebiotics is constantly evolving as more information becomes available about the role that gut microbiota plays in maintaining and promoting health. The most recent definition of dietary prebiotics is “selectively fermented ingredients that induce specific changes in the composition and/or activity of the gut microbiota, benefiting the host’s health.” Several properties must be present for a substance to be considered prebiotic. A prebiotic should resist digestion in the upper gastrointestinal tract and selectively stimulate beneficial bacteria in the gut to induce changes in the microbiota profile, inducing luminal or systemic effects that are beneficial to the host’s health. Prebiotics are thought to help manage several chronic diseases by preventing colorectal cancer, improving osteoporosis, enhancing intestinal health, lowering lipids, and affecting cardiovascular health, obesity, and potentially type 2 diabetes (especially in cases of dyslipidemia and insulin resistance). Seaweed-derived polysaccharides (hydrocolloids) are a novel source of potentially important prebiotics.
Prebiotics are effective against chronic inflammatory bowel disease in transgenic rats by preventing the development of colitis. This protective effect was seen in association with an increase in the number of bifidobacteria and lactobacilli in the intestine. A study by Sweeney T. et al. investigated the effect of feeding growing pigs diets containing seaweed-derived laminarin and fucoidan. Weaning pigs are in a state where they are susceptible to carrying Salmonella typhi and other pathogenic bacteria. The supplemented diets led to higher levels of lactobacilli in the cecum and butyric acid in the cecum and colon. Increased excretion of S. typhimurium in the feces at certain time points during the experiment was also recorded.
Magnesium is also abundant in high-fiber foods such as seaweed. In animal studies, magnesium supplementation prevented the decline in insulin resistance and impaired glucose tolerance and delayed the onset of spontaneous diabetes. Studies indicate an inverse relationship between dietary fiber and the incidence of diabetes among humans. Results from human studies have shown that dietary fiber or foods high in fiber can improve postprandial glycemic response. This is probably due to a decrease in glucose absorption rate and an increase in glucose utilization in the intestine. The effect of magnesium and fiber intake on the development of diabetes was evaluated in 1604 healthy subjects aged 30 years or older. During the follow-up period, a total of 141 incident cases of diabetes were recorded, and an analysis of dietary intake information revealed a statistically significant association between lower magnesium concentrations, lower total dietary fiber intake, or a combination of both, and an increased risk of developing diabetes within the study population.
Source: Source: Mar Drugs. 2016 Mar; 14(3): 60. doi: 10.3390/md14030060