Comparative effects of slowly digestible and resistant starch from rice in high-fat diet-induced obese mice

Prebiotics pectin and resistant starch-type 4 stimulate peptide YY and cholecystokinin to promote satiety, and improve gut microbiota composition

Dietary prebiotics pectin and resistant starch type-4 (RS-4) promote satiety and alter gut microbiota; however, the underlying neurohormonal mechanisms of satiety remain poorly understood. We determined the effects of pectin, RS-4, and their combination on energy balance and gut microbiota composition, and assessed whether the gut hormones peptide YY (PYY) and cholecystokinin (CCK) play a role in fiber-induced satiety. High-fat diet -induced obese male rats (n = 7-8/group) were fed either control, pectin, RS-4, or a combination of pectin and RS-4 diet. We found that pectin, RS-4, and their combination decreased food intake. Pectin alone, or combined with RS-4, shifted substrate utilization towards fat and reduced gains in weight and adiposity. Pectin alone or combined with RS-4 enhanced the expression and plasma concentrations of PYY and CCK. Importantly, systemic blockade of PYY-Y2 and CCK-1 receptors attenuated the hypophagic effects of pectin, and CCK-1 receptor blockade partly attenuated the hypophagia from RS-4. The prebiotics significantly altered fecal β-diversity metrics, suggestive of improvements in gut microbiota composition. Pectin and RS-4 alone, or in combination, were associated with increased relative abundance of phylum Bacteroidota, decreased Firmicutes, and increased concentrations of amino acids and biogenic amines in feces. Collectively, these findings suggest that dietary pectin and RS-4 improved energy balance and gut microbiota composition, and importantly, demonstrated that the satiety effects of these diets were mediated, in part, via enhanced endogenous PYY and CCK signaling.

Enhancing health benefits of milled rice: current status and future perspectives

Milled rice is an essential part of the regular diet for approximately half of the world's population. Its remarkable commercial value and consumer acceptance are mostly due to its promising cooking qualities, appealing sensory properties, and longer shelf life. However, the significant loss of the nutrient-rich bran layer during milling makes it less nutritious than the whole grain. Thus, enhancing the nutritive value of milled rice is vital in improving the health and wellbeing of rice consumers, particularly for those residing in the low-economic zones where rice is the primary source of calories and nutrition. This article provides a critical review on multiple frontiers of recent interventions, such as (1) infusing the genetic diversity to enrich amylose and resistant starch to reduce glycaemic index, (2) enhancing the minerals and vitamins through complementary fortification and biofortification as short and long-term interventions, and (3) developing transgenic solutions to improve the nutrient levels of milled rice. Additionally, the review highlights the benefits of functional ingredients of milled rice to human health and the potential of enhancing them in rice to address the triple burden of malnutrition. The potential merit of milled rice concerning food safety is also reviewed in this article.

Effects of Rice with Different Amounts of Resistant Starch on Mice Fed a High-Fat Diet: Attenuation of Adipose Weight Gain

Increasing the amount of resistant starch (RS) in the diet may confer protective effects against chronic diseases. Rice, a good dietary source of carbohydrates, also contains RS. However, it remains unclear if RS at the amount consumed in cooked rice has a health benefit. To address the question, we examined the effects of cooked rice containing different levels of RS in a diet-induced obesity rodent model. Rice containing RS as low as 1.07% attenuated adipose weight and adipocyte size gain, induced by a moderately high-fat (HF) diet, which correlated with lower leptin levels in plasma and adipose tissue. Rice with 8.61% RS increased fecal short-chain fatty acid levels, modulated HF-diet-induced adipose triacylglycerol metabolism and inflammation-related gene expression, and increased fecal triglyceride excretion. Hence, including rice with RS level at ≥1.07% may attenuate risks associated with the consumption of a moderately HF diet.