The gut-brain axis mediates sugar preference.

The taste of sugar is one of the most basic sensory percepts for humans and other animals. Animals can develop a strong preference for sugar even if they lack sweet taste receptors, indicating a mechanism independent of taste1-3. Here we examined the neural basis for sugar preference and demonstrate that a population of neurons in the vagal ganglia and brainstem are activated via the gut-brain axis to create preference for sugar. These neurons are stimulated in response to sugar but not artificial sweeteners, and are activated by direct delivery of sugar to the gut. Using functional imaging we monitored activity of the gut-brain axis, and identified the vagal neurons activated by intestinal delivery of glucose. Next, we engineered mice in which synaptic activity in this gut-to-brain circuit was genetically silenced, and prevented the development of behavioural preference for sugar. Moreover, we show that co-opting this circuit by chemogenetic activation can create preferences to otherwise less-preferred stimuli. Together, these findings reveal a gut-to-brain post-ingestive sugar-sensing pathway critical for the development of sugar preference. In addition, they explain the neural basis for differences in the behavioural effects of sweeteners versus sugar, and uncover an essential circuit underlying the highly appetitive effects of sugar.

Important Food Sources of Fructose-Containing Sugars and Incident Hypertension: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies.

Background Sugar-sweetened beverages are associated with hypertension. We assessed the relation of important food sources of fructose-containing sugars with incident hypertension using a systematic review and meta-analysis of prospective cohort studies. Methods and Results We searched MEDLINE, EMBASE, and Cochrane (through December week 2, 2018) for eligible studies. For each food source, natural log-transformed risk ratios (RRs) for incident hypertension were pooled using pair-wise meta-analysis and linear and nonlinear dose-response meta-analyses. Certainty in our evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation. We identified 26 reports, including 15 prospective cohorts (930 677 participants; 363 459 cases). Sugar-sweetened beverages showed harmful (RRper-355-mL, 1.10 [95% CI, 1.08, 1.12]) whereas fruit (RRper-240-g, 0.94 [95% CI, 0.96, 0.99]) and yogurt showed protective associations (RRper-125-g, 0.95 [95% CI, 0.94, 0.97]) with incident hypertension throughout the dose range. One hundred percent fruit juice showed a protective association only at moderate doses (RRat-100-mL, 0.97 [95% CI, 0.94, 0.99]). The pair-wise protective association of dairy desserts was not supported by linear dose-response analysis. Fruit drinks or sweet snacks were not associated with hypertension. Certainty of the evidence was "low" for sugar-sweetened beverages, 100% fruit juice, fruit, and yogurt and "very low" for fruit drinks, sweet snacks, and dairy desserts. Conclusions The harmful association between sugar-sweetened beverages and hypertension does not extend to other important food sources of fructose-containing sugars. Further research is needed to improve our estimates and better understand the dose-response relationship between food sources of fructose-containing sugars and hypertension. Registration URL: https://www.clinicaltrials.gov/. Unique identifier: NCT02702375.

A new sensory sweetness definition and sweetness conversion method of five natural sugars, based on the Weber-Fechner Law.

This study's aim is to establish a new sensory sweetness definition and conversion method for five sugars. A "closed-type" question based on triangle test and paired comparison was used for sensory evaluation. The absolute threshold and nine sensory difference threshold values were determined and used to generate a sweet sensory difference strength curve. Defining absolute threshold of sucrose sweetness as 1, the sucrose sweetness at any concentration could be calculated via the curve. After taking the logarithm of each curve, sweetness index was calculated as 1, 1.12, 0.94, 1.29, and 1.25 for sucrose, glucose, fructose, lactose and maltose, respectively. Based on this, each sugar concentration and sweetness could be converted and calculated. Single sugar and mixed-sugars sweetness comparison experiments verified the new sweetness index and sweetness values were more accurate (83.3-100%) than those reported in previous studies. Therefore, this new definition and conversion method established more reliable references for sweet taste sensory applications.

Comparative study of the physicochemical, nutritional, and antioxidant properties of some commercial refined and non-centrifugal sugars.

Three refined and four unrefined branded commercial sugars available in Korea were investigated in terms of pH, soluble solids, moisture, ash content, turbidity, color values, microbial profile, reducing power, 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities, cellular antioxidant activity, and total phytoconstituent (i.e. phenolic, flavonoid, mineral, sucrose, glucose, and fructose) contents using standard analytical protocols such as high-performance liquid chromatography, gas chromatography-flame ionization detector/mass spectrometry, and inductively coupled plasma atomic emission spectroscopy. All tested physicochemical parameters were within the recommended standard levels. Significantly high nutritional and antioxidant properties were observed for the unrefined sugars, especially AUNO® sugar, whereas a high sucrose content was detected for the refined sugars. Hence, this study revealed that the degree of purification affects the nutritional values and antioxidant potentials of sugars. The present findings also indicate that unrefined sugars can be used as sweeteners in sugar-based cuisine to obtain nutritional and antioxidant-rich foodstuff.

Comparison of international methods for the determination of total starch in raw sugars: Part II.

Industrial starch methods in the sugar industry are affected by sugarcane- and processing-derived colourants, and it was presumed that these methods are mathematically equatable. Using the USDA Starch Research method as a reference and factory raw sugars, the impact of colourants on the accuracy, precision, limits of detection/quantification, and mathematical equatability of the starch methods were investigated. Approximately 26-55% of raw sugar colour contributed to starch-I3- absorbance. The exclusion of a colour blank negatively affected method accuracy and the addition of a colour blank confirmed that these methods measured mostly colour instead of starch. Inefficient starch solubilization and the inability to standardize sugar colourants explained why starch results from these methods could not be mathematically equated to the USDA Starch Research method, or among different methods. An industrial starch method that efficiently solubilizes starch and includes a colour blank is urgently needed.