“The rapid increase of autoimmune and inflammatory disorders in industrialized countries in the last few decades indicates dietary choices are one environmental factor contributing to incidence,” said Dr. Lisa Osborne, senior researcher on the study and an assistant professor with UBC Microbiology and Immunology.
“Dietary fibres are potent modulators of immune responses and can control inflammation in multiple diseases, but they’re a very biochemically diverse family. Our study gives us a clearer window into the potential of several sources of fibre in maintaining immune health.”
Dr. Osborne and colleagues exposed groups of mice to a variety of diets—a control five percent cellulose fibre diet, a diet entirely lacking in dietary fibre, or diets enriched (30%) with fibre in either resistant starch, inulin, pectin, or guar gum. Quar gum was the only fibre type that significantly limited the MS-like symptoms.
“Guar beans aren’t that common in western diets, and the gum isn’t used at these high levels as an additive in the west,” says Naomi Fettig, first author on the study and a PhD student with the Department of Microbiology and Immunology at UBC.
“Experts have consistently been saying fibre is good for you—and a variety of fibre sources is important to immune health—but there hasn’t been very much critical work into identifying how the body responds to different fibre types. It’s fascinating that this particular source has such an impact.”
In the US and Canada, the average daily intake of fibre is 15 grams—current recommendations are double that at 30 grams. The recommended values don’t take into account any specific fibre type.
“Incorporating guar beans might be challenging to achieve at the doses we gave to mice,” says Dr. Osborne. “But a guar gum derivative, partially hydrolyzed guar gum, is commercially available as a prebiotic.”
After the gum is broken down by the microbiota of mice, the resulting molecules appeared to reduce the activity and proliferation of a type of CD4+ T cells, Th1 cells, that play a key part in activating the autoimmune response. It’s that response that leads to MS-like symptoms in mice.
The effects of fibre on Th1 cells remained largely unknown prior to this study, and these findings suggest that the biochemical differences in fibre structures can influence diverse immune pathways.
Dr. Osborne and her lab now want to explore the potential benefits in humans—including developing a more detailed understanding of the molecular picture, which might help design therapeutics that offer the benefits of such high guar gum diets in a more practical form.
The specific manifestations of dyslipidemia were related to an increase of TC, LDL-C and TG, and the decrease of HDL-C. In many countries, the degree of changes in blood lipid is graded as an indicator for screening individual blood lipid health status (Jacobson et al., 2015, Catapano et al., 2017, Teramoto et al., 2013).
Lipid levels are a diagnostic indicator for many chronic diseases such as diabetes and CVD (Ofori et al., 2018, Hazavehei et al., 2016). Age, gender, diet and lifestyle can all have an impact on blood lipid levels (Xi et al., 2020). Therefore, the complicated etiology and the development of subsequent diseases make dyslipidemia a concern.
Soluble fiber is believed to play a role in lowering blood lipid levels because of its solubility, high viscosity, and fermentability (Surampudi, Enkhmaa, Anuurad, & Berglund, 2016). However, there is still no clear conclusion on the effect of guar gum, which is recognized as soluble dietary fiber, on blood lipid levels.
Guar gum is a kind of natural galactomannan extracted from the endosperm of Guar seeds, which are mainly produced in India and Pakistan. The Agricultural and Processed Food Products Export Development Authority (APEDA) has announced that India exported 381,880 metric ton (MT, 1 MT = 1000 kg) of guar gum for the worth of 456.96 million US dollars between 2019 and 2020, accounting for 45.11% of the global exports. The average degree of polymerization for guar gum can be as high as 3295, and can improve the intestinal microflora environment through fermentation (Linetzky Waitzberg et al., 2012, Mudgil et al., 2012, Yasukawa et al., 2019). Guar gum is often used as a food additive to emulsify, thicken, and solidify processed foods, such as baked goods, breakfast cereals and dairy products, for its rich dietary fiber and outstanding viscosity (Mortensen et al., 2017). In recent years, studies have demonstrated the feasibility of guar gum as a fat substitute, providing a good option for dieters (Goswami et al., 2019, Rather et al., 2017).
However, due to the diversity of research methods and sample sizes, many studies on the effect of guar gum on blood lipids are different in terms of quality and results. A study of diabetics found that guar gum intervention in the diet for 48 weeks significantly reduced TC and LDL-C concentrations in patients (Groop, Aro, Stenman, & Groop, 1993). However, a 6-month RCT showed that, in addition to lowering LDL-C level in men, guar gum did not alter lipid profiles in diabetic patients compared to the controls (McIvor et al., 1986). The conclusions are also uncertain in studies with subjects with different health conditions, such as hypercholesterolemia or generally healthy people (Landin et al., 1992, Simons et al., 1982, Tuomilehto et al., 1980).
Preventing dyslipidemia and reducing the risk factors for chronic diseases are critical to the health of people today. In this study, we screened and evaluated the quality of the studies about guar gum, and conducted a meta-analysis to provide stronger evidence to support the true effect of guar gum on blood lipid.
reference link :https://www.sciencedirect.com/science/article/pii/S1756464621002541
reference link : Original Research: Open access.
“Inhibition of Th1 activation and differentiation by dietary guar gum ameliorates experimental autoimmune encephalomyelitis” by Lisa Osborne et al. Cell Reports
