Regular Consumption of Biovalorized Okara-Containing Biscuit Improves Circulating Short-Chain Fatty Acids and Fecal Bile Acids Concentrations by Modulating the Gut Microbiome: A Randomized Controlled Crossover Trial

SCOPE

Okara is a fiber-rich food by-product whereby biovalorization with Rhizopus oligosporus can improve its nutritional quality, generating fermentable substrates for improved gut health maintenance. This study evaluates the impact of okara- and biovalorized okara-containing biscuits consumption on gut health in Singapore adults.

METHODS AND RESULTS

Participants consumed control (C), 20% flour-substituted okara- (AOK) and biovalorized okara- (RO) biscuits for 3 weeks, with assessment of gut metabolites, microbiome, and dietary intake. Fecal valeric acid was significantly higher with RO compared to AOK (P = 0.005). RO and AOK had significantly higher total serum short-chain fatty acids (P = 0.002&0.018 respectively) and acetic acid (P = 0.007&0.030 respectively) compared to C. Higher serum propionic acid (P = 0.004) and lower fecal lithocholic acid (P = 0.009) were observed with RO. Although serum zonulin showed no significant difference, AOK reduced Clostridiales while RO increased Bifidobacterium.

CONCLUSION

Okara consumption improved serum SCFA regardless of fermentation while biovalorised okara further enhanced gut metabolites by modulating gut microbiome. This article is protected by copyright. All rights reserved.

Postprandial glycemic and circulating SCFA concentrations following okara- and biovalorized okara-containing biscuit consumption in middle-aged and older adults: a crossover randomized controlled trial

Okara is a high-fiber food by-product that can be biotransformed with Rhizopus oligosporus to improve its nutritional value and palatability. This research aims to assess postprandial changes in glycemic-related and lipid-related outcomes in middle-aged and older Singaporeans following okara- and biovalorized okara-containing biscuit consumption. Fifteen participants (58 ± 6 years old, mean ± SD) completed the randomized crossover study. Participants were provided control (C), okara (AOK)-, and biovalorized okara (RO)-containing biscuits in separate 4 h mixed meal tolerance tests. Serum glucose and insulin, insulin indices, serum short-chain fatty acids (SCFA) and lipid-lipoprotein panels, and sensory analysis were assessed. Glucose-stimulated insulin secretion was significantly lower for RO than for C (p: 0.035) while log insulin incremental area under the curve (AUC) was significantly lower for AOK compared to that for C (p: 0.023). The estimated insulin sensitivity index and estimated metabolic clearance rate were significantly higher for AOK compared to that for C (p: 0.025 and 0.016 respectively). Normalized AUC for total SCFA was significantly higher for RO compared to that for C (p: 0.038). Normalized AUC for LDL-cholesterol was significantly higher for AOK than for C (p: 0.010). No significant difference was noted for glucose, total cholesterol, HDL-cholesterol, and triglyceride concentrations. RO had greater flavor and overall liking than AOK (p: 0.007 and 0.017 respectively). Biscuits incorporated with okara or biovalorized okara can attenuate postprandial insulin responses. RO offered a greater SCFA response than C, indicating improved SCFA concentrations upon consumption of okara improved with fermentation. The trial was registered under https://www.clinicaltrials.gov (NCT03978104, 25 May 2019).

Impact of 5-Hydroxytryptophan Supplementation on Gut Microbiota Composition of Older Adults With Different Sleep Status in Singapore: A Randomized Controlled Trial

Objectives

The gut and brain communicate bidirectionally through the gut brain axis. Lower microbial diversity has been observed in populations with sleep disturbances. 5-Hydroxytryptophan (5-HTP) is known as a potential modulator of sleep quality, while its impact on the gut remains unclear. The aim of this study was to assess the impact of 5-HTP on gut microbiota in older Singaporeans with different sleep status.

Methods

This study is a single-blinded, 12-week parallel randomized controlled trial. Thirty older adults (66 ± 3 years, mean ± SD) were randomly assigned to either consume or not consume 100 mg 5-HTP daily. Their baseline sleep status was evaluated using global sleep score (GSS): GSS ≤ 5 (good sleepers, n:17); GSS > 5 (poor sleepers: n:13). Characterization of the bacterial population from the stool samples collected at week 0 and 12 was analyzed through 16S metagenomic sequencing. Microbiota composition between GSS ≤ 5 and GSS > 5 was compared via MetaStat analysis. The main effect and interaction of 5-HTP on gut microbiota composition was evaluated by mixed analysis of variance (ANOVA).

Results

At baseline, poor sleepers have a significantly lower relative abundance of Firmicutes than good sleepers (GSS > 5: 3.78 × 10⁻¹ ± 5.43 × 10⁻²; GSS ≤ 5: 4.33 × 10⁻¹ ± 9.32 × 10⁻²; p-value: 0.048). After a 12-week consumption of 5-HTP, subjects with GSS > 5 showed an increase in α-diversity (Simpson_5-HTP vs. Simpson_Control: 0.037 ± 0.032 vs. −0.007 ± 0.022; p_interaction: 0.013). 5-HTP supplementation also showed interaction effects on the relative abundance of Bacteroidota (Bacteroidota_5-HTP vs. Bacteroidota_Control: −1.03 × 10⁻¹ ± 4.99 × 10⁻² vs. −3.06 × 10⁻² ± 4.39 × 10⁻²; p_interaction: 0.019) and Firmicutes (Firmicutes_5-HTP vs. Firmicutes_Control: 1.10 × 10⁻¹ ± 2.40 × 10⁻² vs. 2.02 × 10⁻² ± 7.82 × 10⁻²; p_interaction: 0.031). No significant changes were observed for GSS ≤ 5 group.

Conclusions

In older adults, 5-HTP consumption modulated gut microbiota composition in poor sleepers (GSS > 5). However, no influence to the gut microbiota was observed in good sleepers (GSS ≤ 5).

Funding Sources

NUS iHealthtech Microbiome in Health, Disease and Ageing.

Biovalorized Okara Consumption Improves Gut Metabolites by Modulating Gut Microbiome: A Randomized Controlled Crossover Trial

Objectives

Okara is a major food by-product of soymilk or tofu production, particularly rich in dietary fiber. Biovalorization with Rhizopus oligosporus can improve its nutritional quality with greater soluble fiber, bioavailable isoflavones, and antioxidants. These nutrients are fermented by the gut microbiota to generate gut metabolites involved in gut health maintenance. This study evaluates the impact of okara and biovalorized okara- containing biscuits consumption on gut health in middle-aged and older Singaporeans.

Methods

Healthy participants (n = 15) of the crossover trial were randomly allocated to 3-week interventions of 100 g of control (C), 20% flour substituted autoclaved okara- (AOK), and 20% four substituted R. oligosporus biovalorized okara- (RO) containing biscuits, with 3-week washout periods. Pre- and post- intervention serum short-chain fatty acids (SCFA), fecal SCFA, fecal bile acids, serum zonulin, gastrointestinal symptoms, and dietary intakes were assessed. Pre- and post- intervention fecal 16S ribosomal RNA V3-V4 sequencing was also investigated for gut microbiome analysis. Results are presented as change value mean (95% confidence interval).

Results

Amongst fecal SCFA, only valeric acid (µmol/g) observed a significant difference, higher with RO compared to AOK (0.16 (0.01, 0.30) vs −0.20 (−0.34, −0.05), P = 0.005). RO and AOK had significantly higher total serum SCFA (P = 0.002 & 0.018 respectively) and serum acetic acid (P = 0.007 & 0.030 respectively) compared to C. RO had significant improvements with higher serum propionic acid (µmol/L) (RO: 3.04 (0.80, 5.27) vs C: −2.65 (−4.97, −0.33), P = 0.004) and lower fecal lithocholic acid (mg/g) (a secondary bile acid) (RO: −0.11 (−0.20, −0.02) vs C: 0.10 (0.01, 0.19), P = 0.009) contrasted to C. Although serum zonulin showed no significant difference, AOK induced a reduction in Clostridiales while RO increased Bifidobacterium. Okara consumption increased dietary fiber intake, with greater soluble fiber intake from RO compared to AOK and C (P = 0.018 & 0.019 respectively), aligning with the greater flatulence felt by participants on RO.

Conclusions

Okara consumption improved serum SCFA rather than fecal SCFA, regardless of fermentation. Biovalorized okara consumption further improved SCFA and bile acid profiles by modulating gut microbiome.

Funding Sources

Singapore Ministry of Education.

The Impact of 5-Hydroxytryptophan Supplementation on Sleep Quality of Older Adults in Singapore: A Randomized Controlled Trial

Objectives

Sleep quality has been associated with a number of health conditions such as cognitive impairment and cardiovascular disease. 5-Hydroxytryptophan (5-HTP) is known as a precursor of the sleep regulating serotonin and melatonin. However, 5-HTP's efficacy for improving sleep in older adults is unclear. The aim of this study is to assess the impact of 5-HTP on sleep quality in older Singaporean adults.

Methods

This study is a single-blinded, 12-week parallel randomized controlled trial, where 20 older adults (67 ± 4 years, mean ± SD; 8 M, 12 F) were randomly assigned to either consume or not consume 100 mg 5-HTP daily. Sleep quality data were collected every 4 weeks via both subjective and objective measures such as Pittsburg Sleep Quality Index (PSQI) questionnaire and actigraphy watch. A global sleep score (GSS) was obtained from the PSQI, where a GSS > 5 has been validated to be associated with poor sleep quality. In addition, other sleep quality components that were also extracted include total sleep time (TST), sleep latency (SL) and sleep efficiency (SE). The main effect and interaction of 5-HTP on sleep were evaluated by repeated-measure analysis of variance (ANOVA).

Results

At baseline, subjects had an overall GSS of 5.9 ± 3.1 a.u. (5-HTP group: 6.3 ± 3.8 a.u.; Control group: 5.5 ± 2.3 a.u.) and this indicated poor sleep quality. Consumption of 5-HTP after 4 and 8 weeks showed a favorable decrease in their objective SL (SLObj) from their baseline (week 4: −18.2 ± 21.1 min; week 8: −17.8 ± 19.2 min). On the other hand, the control group did not display desirable change in SLObj (week 4: 2.4 ± 21.6 min; week 8: 1.5 ± 21.4 min). Repeated-measures ANOVA revealed a significant treatment-by-time effect between 5-HTP consumption and SLObj at week 4 (P = 0.045) and week 8 (P = 0.033), but not at week 12 (P = 0.135). A significant treatment-by-time decrease in subjective TST (−0.1 ± 0.4 hrs, P = 0.027) observed at week 12. No changes in GSS and other subjective and objective measures of sleep quality were detected.

Conclusions

Older adults had poor sleep quality and 5-HTP supplementation helped reduce sleep latency for up to 8 weeks. Prolonged effects were not observed, and this may be due to acclimation of the body to longer-term 5-HTP supplementation.

Funding Sources

NUS iHealthtech Microbiome in Health, Disease and Ageing.

Postprandial Glycemic, Insulinemic, and Short-Chain Fatty Acids Responses Following the Consumption of Okara and Biovalorized Okara Incorporated Biscuits

Objectives

Okara is a fiber-rich food processing by-product. However, it is underutilized as food due to its rapid putrefaction and poor sensorial properties. Valorization via fermentation (biovalorization) can alleviate its undesirable qualities while augmenting its soluble fiber content. The increase in soluble fiber may improve postprandial glycemic and insulinemic responses, potentially via generation of short-chain fatty acids (SCFAs) from colonic bacteria fermentation. This study aimed to assess the effect of consuming okara and biovalorized okara-containing biscuits on postprandial glucose, insulin and SCFAs responses in older Singaporeans.

Methods

Fifteen healthy middle-aged and older Singaporeans participated in a randomized controlled crossover trial. Subjects underwent a 4-hour mixed meal tolerance test with 100 g ingestion of 3 types of biscuits – control (C, no okara), biovalorised okara (RO) and autoclaved okara (AOK). RO and AOK biscuits were produced by 20%

substitution of wheat flour with okara powder that was fermented with Rhizopus oligosporus (7% w/w) or autoclaved. The 4-hour incremental area under the curve (iAUC) of glucose, insulin and SCFAs (acetate, propionate and butyrate) were assessed. β-cell function was evaluated based on glucose stimulated insulin secretion, using a ratio of 4-hour AUC of insulin to glucose. Estimated insulin sensitivity (ISI) and metabolic clearance rate (MCR) were assessed with Stumvoll Index.

Results

Although no difference in glucose response was noted, RO showed significantly lower insulin iAUC (RO: 8931 ± 1058 mU/L × min, mean ± SE; C: 10271 ± 866 mU/L × min, p = 0.021) and improved β-cell function (p = 0.028) compared to C. AOK yielded significantly greater ISI and MCR compared to C (pISI = 0.016, pMCR = 0.009) while RO showed no difference against AOK or C. Significantly higher acetate and total SCFAs iAUC were evident for both RO and AOK relative to C (C vs RO: pacetate = 0.012, ptotal SCFA = 0.001; C vs AOK: pacetate = 0.015, ptotal SCFA = 0.001). AOK also had significantly greater propionate and butyrate iAUC compared to C (C vs AOK: pacetate = 0.002, pbutyrate = 0.001).

Conclusions

Consumption of okara and biovalorized okara-containing biscuits offers the benefit of attenuating postprandial insulinemic response possibly via SCFAs modulation.

Funding Sources

Singapore Ministry of Education