Do polyphenols affect body fat and/or glucose metabolism?

Background

Obesity is reaching epidemic proportions with 51% of the population expected to be obese by 2030. Recently, polyphenols have been highlighted as an effective approach to managing obesity and associated risks. Polyphenols are a large class of bioactive plant compounds classified into two major categories: flavonoids which are distinguished by the fundamental C6-C3-C6 skeleton and non-flavonoids.

Objective

This systematic review evaluated the effect of different polyphenol sources in overweight and obese people with and without type 2 diabetes. The primary outcome was lipid profile and the secondary outcomes were blood glucose, HbA1c (%), HOMA-IR, weight, and body mass index.

Method

A search was undertaken in PubMed, Web of Science, Medline, and Wiley for randomized control trials that assessed different sources of polyphenols in overweight and obese people with or without type 2 diabetes. The quality of the included studies was assessed using the National Heart, Lung, and Blood Institute Quality Assessment Tool.

Result

The search yielded 935 studies, of which six randomized control trials met the inclusion criteria. Five studies found no significant difference in lipid profile between the control and intervention groups in triglycerides, total cholesterol, LDL cholesterol, and HDL cholesterol. However, one study showed significant differences in triglycerides (p = 0.04) and HDL cholesterol (p = 0.05) between the two groups with no significant difference in total cholesterol and LDL cholesterol. There were no significant changes in blood glucose observed in the included studies, with only two studies reporting a significant difference in A1c between the groups. Four studies found no difference in HOMA-IR, while one study showed a significant decrease in HOMA-IR in the intervention group compared to the control group. Three studies reported no difference in BMI or weight between the two groups.

Conclusion

The data associated with the specific health benefits of polyphenols and their sources in people with overweight, obese, and type 2 diabetes are still limited, so further research is required to support their use and prove their benefits.

Could VGF and/or its derived peptide act as biomarkers for the diagnosis of neurodegenerative diseases: A systematic review

BACKGROUND

The increasing ageing population has led to an increase in the prevalence of neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). However, as yet, there are no simple biomarkers to predict the onset of such diseases. Recently, VGF and its peptides have been highlighted in neurodegenerative diseases. VGF (non-acronymic) is a polypeptide induced in PC12 cells by neurotrophic factors.

OBJECTIVE

This systematic review aimed to determine whether VGF and/or its derived peptides can be used as biomarkers for the diagnosis of ALS, PD, and AD with specific attention to (1) the levels of VGF and/or its derived peptides, (2) amyloid-beta, (3) dopamine, and (4) cognitive score.

METHODOLOGY

A search was undertaken in the Ovid EMBASE, Cochrane Library, PubMed, Scopus, and Web of Science for observational studies. Publications that assessed the level of VGF and/or its derived peptides among people with neurodegenerative diseases and compared them with healthy people were included. The quality of the included studies was assessed using the National Heart, Lung, and Blood Institute Quality Assessment Tool.

RESULT

A search of the databases yielded 834 studies, of which, eight observational studies met the inclusion criteria with a total of 673 participants (51.7% males) aged >18 years. Seven studies showed significant decreases in VGF and its derived peptides in adults with AD, PD, and ALS compared to healthy controls (p<0.05). However, one study showed that there was no significant difference in VGF in AD compared to healthy control(p>0.05). Furthermore, only one study reported that VGF levels were positively correlated with those of tissue dopamine but not with Aβ1-42, and low levels of VGF were associated to cognitive deficits.

CONCLUSION

The use of VGF and its derivatives for the diagnosis of PD, ALS, AD remains unclear, so further investigation of the role of VGF in neurodegenerative diseases and pathophysiology is needed to provide new insights.