Publications by authors named "Darel Wee Kiat Toh"

9 Publications

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Enhancing the cardiovascular protective effects of a healthy dietary pattern with wolfberry (Lycium barbarum): A randomized controlled trial.

Am J Clin Nutr 2021 May 8. Epub 2021 May 8.

Department of Food Science & Technology, Faculty of Science, National University of Singapore, Singapore, Singapore.

Background: The consumption of wolfberry (Lycium barbarum), a rich source of carotenoids and bioactive polysaccharides, may serve as a potential dietary strategy for cardiovascular disease (CVD) risk management although limited studies examined its effects as whole fruits.

Objectives: To investigate the impact of wolfberry consumption as part of a healthy dietary pattern on vascular health-related outcomes and classical CVD risk factors in middle-aged and older adults in Singapore.

Methods: This is a 16-week, parallel design, randomized controlled trial. All participants (n = 40) received dietary counselling to follow healthy dietary pattern recommendations with the wolfberry group given additional instructions to cook and consume 15 g/d whole, dried wolfberry with their main meals. Biomarkers of vascular function (flow-mediated dilation, plasma total nitrate/nitrite, endothelin-1, and intercellular adhesion molecule-1), vascular structure (carotid intima-media thickness) and vascular regeneration (endothelial progenitor cell count, plasma angiopoietin 1 and angiopoietin 2), were assessed at baseline and postintervention. Serum lipid-lipoproteins and blood pressure were evaluated every 4 weeks.

Results: All participants showed an improved compliance toward the healthy dietary pattern. This was coupled with marked rises in total nitrate/nitrite concentrations (mean change wolfberry: 3.92 ± 1.73 nmol/mL; control: 5.01 ± 2.55 nmol/L) and reductions in endothelin-1 concentrations (wolfberry: -0.19 ± 0.06 pg/mL; control: -0.15 ± 0.08 pg/mL). Compared with the control which depicted no changes from baseline, the wolfberry group had a significantly higher HDL cholesterol (0.08 ± 0.04 mmol/L), as well as lower Framingham predicted long-term CVD risk (-0.8 ± 0.5%) and vascular age (-1.9 ± 1.0 y) postintervention. No differences were observed in the other vascular health-related outcomes.

Conclusions: In middle-aged and older adults, adherence to a healthy dietary pattern improves vascular tone. Incorporating wolfberry to the diet further improves blood lipid-lipoprotein profile and may lower long-term CVD risk. This study was registered at clinicatrials.gov as NCT03535844.
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http://dx.doi.org/10.1093/ajcn/nqab062DOI Listing
May 2021

Wolfberry () Consumption with a Healthy Dietary Pattern Lowers Oxidative Stress in Middle-Aged and Older Adults: A Randomized Controlled Trial.

Antioxidants (Basel) 2021 Apr 7;10(4). Epub 2021 Apr 7.

Department of Food Science & Technology, Faculty of Science, National University of Singapore, 2 Science Drive 2, Singapore 117543, Singapore.

Incorporating zeaxanthin-rich wolfberry () into a healthy dietary pattern may augment its antioxidant potential. The present 16-week, parallel design randomized controlled trial aimed to investigate the impact of adhering to a healthy dietary pattern, either with or without whole dried wolfberry (15 g/d) on oxidative stress status (plasma malondialdehyde and 8-iso-prostaglandin F2α) in middle-aged and older adults. Changes to carotenoids status (plasma and skin carotenoids) and body composition were further evaluated to explore potential mechanisms which underlie the antioxidant properties of wolfberry. Plasma 8-iso-prostaglandin F2α, plasma zeaxanthin and skin carotenoids status were significantly raised in the wolfberry consuming group ( = 22; < 0.05) compared to the control group which showed no changes ( = 18). Likewise in the wolfberry group only, inverse association was observed between the change values of plasma zeaxanthin and plasma 8-iso-prostaglandin F2α (-0.21 (-0.43, 0.00) ng/µmol, regression coefficient (95% CI); = 0.05). Wolfberry consumption with a healthy dietary pattern may serve as a dietary strategy to attenuate lipid peroxidation among middle-aged and older adults who are at a heightened risk of oxidative stress induced age-related disorders. The antioxidant properties of wolfberry may be attributed to its rich zeaxanthin content.
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http://dx.doi.org/10.3390/antiox10040567DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8067708PMC
April 2021

Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Strength: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Nutrients 2021 Feb 18;13(2). Epub 2021 Feb 18.

Department of Food Science & Technology, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.

Although animal protein is usually considered to be a more potent stimulator of muscle protein synthesis than plant protein, the effect of protein source on lean mass and muscle strength needs to be systematically reviewed. This study aimed to examine potential differences in the effect of animal vs. plant protein on lean mass and muscle strength, and the possible influence of resistance exercise training (RET) and age. The following databases were searched: PubMed, Embase, Scopus and CINAHL Plus with Full Text, and 3081 articles were screened. A total of 18 articles were selected for systematic review, of which, 16 were used for meta-analysis. Total protein intakes were generally above the recommended dietary allowance at the baseline and end of intervention. Results from the meta-analyses demonstrated that protein source did not affect changes in absolute lean mass or muscle strength. However, there was a favoring effect of animal protein on percent lean mass. RET had no influence on the results, while younger adults (<50 years) were found to gain absolute and percent lean mass with animal protein intake (weighted mean difference (WMD), 0.41 kg; 95% confidence interval (CI) 0.08 to 0.74; WMD 0.50%; 95% CI 0.00 to 1.01). Collectively, animal protein tends to be more beneficial for lean mass than plant protein, especially in younger adults.
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http://dx.doi.org/10.3390/nu13020661DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7926405PMC
February 2021

Skin carotenoid status and plasma carotenoids: biomarkers of dietary carotenoids, fruits and vegetables for middle-aged and older Singaporean adults.

Br J Nutr 2021 Jan 14:1-10. Epub 2021 Jan 14.

Department of Food Science & Technology, Faculty of Science, National University of Singapore, Science Drive 3, Singapore, Singapore.

Skin carotenoid status (SCS) measured by resonance Raman spectroscopy (RRS) may serve as an emerging alternative measurement for dietary carotenoid, fruit and vegetable (FV) intake although its application had not been assessed in a middle-aged and older population in Asia. This cross-sectional study aims to concurrently examine the use of SCS and plasma carotenoids to measure FV and carotenoid intake in a middle-aged and older population, taking into consideration potential socio-demographic and nutritional confounders. The study recruited 103 middle-aged and older adults (mean age: 58 years) in Singapore. Dietary carotenoids and FV, plasma carotenoid concentration and SCS were measured using 3-d food records, HPLC and a biophotonic scanner which utilised RRS, respectively. Adjusted for statistically defined socio-demographic covariates sex, age, BMI, prescription medication and cigarette smoking, plasma carotenoids and SCS showed positive associations with dietary total carotenoids (βplasma: 0·020 (95 % CI 0·000, 0·040) µmol/l/mg, P = 0·05; βskin: 265 (95 % CI 23, 506) arbitrary units/mg, P = 0·03) and FV (βplasma: 0·076 (95 % CI 0·021, 0·132) µmol/l per FV serving, P = 0·008; βskin: 1036 (95 % CI 363, 1708) arbitrary units/FV serving, P = 0·003). The associations of SCS with dietary carotenoid and FV intake were null with the inclusion of dietary PUFA, fibre and vitamin C as nutritional covariates (P > 0·05). This suggests a potential influence of these nutritional factors on carotenoid circulation and deposition in the skin. In conclusion, SCS, similar to plasma carotenoids, may serve as a biomarker for both dietary carotenoid and FV intake in a middle-aged and older Singaporean population.
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http://dx.doi.org/10.1017/S0007114521000143DOI Listing
January 2021

Skin carotenoids status as a potential surrogate marker for cardiovascular disease risk determination in middle-aged and older adults.

Nutr Metab Cardiovasc Dis 2021 02 26;31(2):592-601. Epub 2020 Oct 26.

Department of Food Science & Technology, Faculty of Science, National University of Singapore, Singapore. Electronic address:

Background And Aims: Upon consumption, carotenoids, which may attenuate cardiovascular disease (CVD) risk, diffuse from the blood and accumulate in the skin. This study aimed to assess the associations between dietary, plasma, and skin carotenoids with CVD risk indicators and to examine the mediational role of plasma carotenoids in the relationship between skin carotenoids status (SCS) and CVD risk.

Methods And Results: Dietary, plasma, and skin carotenoids were assessed in a cross-sectional study from a community in Singapore (n = 103) aged 50 to 75 y. Multiple linear regression and binary logistics regression models were used to examine the associations between the carotenoids status with classical CVD risk factors and composite CVD risk indicators. After controlling for covariates, SCS and plasma carotenoids were inversely associated with systolic blood pressure (skin: P < 0.001; plasma: P < 0.05) and diastolic blood pressure (skin: P < 0.001; plasma: P < 0.005). Additionally, each increment of 1000 in SCS was associated with an odds ratio of 0.924 (P < 0.01) for metabolic syndrome diagnosis and 0.945 (P < 0.05) for moderate to high CVD risk classification. Associations between SCS and composite CVD risk indicators were null when adjusted for the corresponding plasma carotenoids, indicating complete mediation. Dietary carotenoids, however, showed no relationship with the CVD risk indicators.

Conclusion: Carotenoids bioavailability may be important for cardiovascular protection. SCS, driven by the corresponding plasma carotenoids, could be a potential noninvasive surrogate marker for CVD risk determination in middle-aged and older adults.

Clinical Trial Registration: NCT03554954, https://clinicaltrials.gov/.

Trial Registration Date: 13 June 2018.
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http://dx.doi.org/10.1016/j.numecd.2020.10.016DOI Listing
February 2021

Effects of fatty acids composition in a breakfast meal on the postprandial lipid responses: a systematic review and meta-analysis of randomised controlled trials.

Int J Food Sci Nutr 2020 Nov 29;71(7):793-803. Epub 2020 Mar 29.

Department of Food Science and Technology, Faculty of Science, National University of Singapore, Singapore.

Replacement of food rich in saturated fatty acids (SFAs) with unsaturated fatty acids (UFAs) is a well-known dietary strategy to reduce the risk of cardiovascular disease while its impact on postprandial blood lipids is less examined. This study assessed the effects of fatty acids composition on the postprandial triglycerides and cholesterol responses. Seventeen randomised controlled trials were identified and pooled analysis results revealed that consumption of a UFAs-rich or an SFAs-rich breakfast meal did not acutely affect postprandial triglycerides and cholesterol responses. However, subgroup analysis observed that triglycerides incremental area under the curve was lower with an SFAs-rich meal (SMD: -0.36; 95% CI: -0.57, -0.15) over a less than 8 h duration, while was higher (SMD: 0.59; 95% CI: 0.05, 1.23) over a longer postprandial duration. It suggests that the postprandial duration is of importance when evaluating the effects of fatty acids composition on blood lipid responses.
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http://dx.doi.org/10.1080/09637486.2020.1744534DOI Listing
November 2020

Incorporating healthy dietary changes in addition to an increase in fruit and vegetable intake further improves the status of cardiovascular disease risk factors: A systematic review, meta-regression, and meta-analysis of randomized controlled trials.

Nutr Rev 2020 07;78(7):532-545

Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Singapore.

Context: Fruit and vegetable (FV) intake has been associated with a reduced risk of cardiovascular disease (CVD). Beyond increasing FV intake, the incorporation of other healthy dietary changes may help to further attenuate CVD risk.

Objective: A systematic review and meta-analysis was conducted to determine the effect of increasing FV intake to > 3 servings daily as well as incorporating other healthy dietary changes on classical CVD risk factors through a systematic review, meta-regression, and meta-analysis of randomized controlled trials.

Data Sources: The following databases were searched: PubMed, CINAHL Plus with Full Text, Medline (ProQuest), and Cochrane Library.

Data Extraction: 82, 24, and 10 articles were selected for the systematic review, meta-regression, and meta-analysis, respectively.

Data Analysis: Meta-regression analysis showed a dose-dependent response between the number of FV servings consumed in each intervention group and the blood triglyceride change value. Pooled weighted mean differences from the meta-analysis suggested that increasing FV intake to > 3 servings daily contributes to significant decreases in triglyceride (-0.10 mmol/L; 95%CI, -0.18 to -0.01) and diastolic blood pressure (-1.99 mmHg; 95%CI, -2.28 to -1.70) as well as marginal decreases in total cholesterol and low-density lipoprotein cholesterol. While improvements were observed in the triglyceride and high-density lipoprotein cholesterol response following the incorporation of other healthy dietary changes, no additional cardiovascular benefits were observed when FV intake was increased from > 3 to > 5 servings daily.

Conclusion: Increasing FV intake to > 3 servings daily improves CVD risk factors, most distinctly triglyceride, especially when complemented with other healthy dietary changes.
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http://dx.doi.org/10.1093/nutrit/nuz104DOI Listing
July 2020

Lowering breakfast glycemic index and glycemic load attenuates postprandial glycemic response: A systematically searched meta-analysis of randomized controlled trials.

Nutrition 2020 03 1;71:110634. Epub 2019 Nov 1.

Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Singapore. Electronic address:

Low glycemic index (GI) diets are recommended to reduce the risk for chronic diseases by managing postprandial elevations in blood glucose and insulin. However, to our knowledge, a systematic review of randomized controlled trials (RCTs) to investigate this relationship and interpret its clinical relevance has yet to be performed. This review aims to assess the effect of low versus high GI breakfast meals on postprandial glycemic and insulinemic responses in adults. Two researchers independently screened 1100 articles from PubMed, CINAHL, Medline, and Cochrane databases and extracted data from 11 qualified RCTs. Meta-analyses were performed to calculate overall effect sizes of postintervention blood glucose concentration change values at different time points (60, 90, and 120 min) using a random-effects model, reporting their weighted mean differences (WMDs) and 95% confidence intervals (CIs). Low GI breakfasts significantly reduced postprandial blood glucose concentrations at all time points: 60 min (WMD: -1.32 mmol/L; 95% CIs, -1.64 to -0.99), 90 min (WMD: -0.74 mmol/L; 95% CI, -0.92 to -0.56), and 120 min (WMD: -0.44 mmol/L; 95% CI, -0.63 to -0.26). Further analyses not only indicated similar trends following the stratification of studies according to the glycemic load, but also showed a more pronounced decline in glycemic response among individuals with metabolic impairments. These results highlight the benefits of lowering breakfast meal GI to provide clinically relevant reductions in acute glucose response.
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http://dx.doi.org/10.1016/j.nut.2019.110634DOI Listing
March 2020

Daily consumption of essence of chicken improves cognitive function: a systematically searched meta-analysis of randomized controlled trials.

Nutr Neurosci 2021 Mar 25;24(3):236-247. Epub 2019 May 25.

Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Singapore, Singapore.

Essence of chicken (EC) is a dietary supplement with potential benefits on one's cognitive performance. The purpose of this meta-analysis is to evaluate the effects of consuming EC on cognitive function, applying extensively represented domains. Six databases were systematically searched to yield 1760 articles. These articles were independently screened to obtain 8 eligible articles with a pooled population of 794 subjects which is more than twice the population size considered in the previous meta-analyses. Largely, favorable effects on cognitive function were observed following daily EC intake, specifically in the working memory domain (standardized mean difference: 0.31, 95% CI: 0.16, 0.46), one of the core components in executive function which showed statistically significant results. Furthermore, the observed results were also robust to sensitivity analyses and subgroup analyses. This suggests that when consumed daily, EC may improve the mental processing aspect of cognitive function amongst the healthy population.
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http://dx.doi.org/10.1080/1028415X.2019.1619984DOI Listing
March 2021