Effect of Virgin Coconut Oil Supplementation on Cognition of Individuals with Mild-to-Moderate Alzheimer's Disease in Sri Lanka (VCO-AD Study): A Randomized Placebo-Controlled Trial

Improving cognitive impairment through chronic consumption of natural compounds/extracts: a systematic review and meta-analysis of randomized controlled trials

Introduction

This systematic review and meta-analysis aimed to compare the efficacy of extended supplementation (≥6 weeks) with natural compounds or extracts in improving cognitive function in patients with mild cognitive impairment (MCI) or Alzheimer's disease (AD).

Methods

A comprehensive literature search was conducted across Cochrane, PubMed, PsycARTICLES, Scopus, and Web of Science databases from inception to April 10, 2024. Eligible studies were randomized controlled trials evaluating cognitive outcomes in patients with MCI or AD using the Mini-Mental State Examination (MMSE) and the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog).

Results

From an initial pool of 6,687 articles, 45 were deemed relevant for qualitative analysis. Of these, 37 studies demonstrated improvements or positive trends in cognitive outcomes with natural compound or extract supplementation. A total of 35 studies met the criteria for meta-analysis. The meta-analysis, involving 4,974 participants, revealed significant improvements in ADAS-Cog scores (pooled standardized mean difference = -2.88, 95% confidence interval [CI]: -4.26 to -1.50; t24 = -4.31, p < 0.01) following supplementation. Additionally, a suggestive trend toward improvement in MMSE scores was observed in a subgroup analysis of 1,717 participants (pooled standardized mean difference = 0.76, 95% CI: 0.06 to 1.46, t18 = 2.27, p = 0.04).

Conclusion

These findings support the potential cognitive benefits of extended (≥6 weeks) supplementation with natural compounds or extracts in individuals with MCI or AD. Further research is warranted to confirm these results and elucidate the underlying mechanisms.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/.

Analysis of 26 Studies of the Impact of Coconut Oil on Lipid Parameters: Beyond Total and LDL Cholesterol

Coconut oil (CNO) is often characterized as an "artery-clogging fat" because it is a predominantly saturated fat that ostensibly raises total cholesterol (TChol) and LDL cholesterol (LDL-C). Whereas previous analyses assessed CNO based on the relative effects on lipid parameters against other fats and oils, this analysis focuses on the effects of CNO itself. Here, we review the literature on CNO and analyze 984 lipid profile data sets from 26 CNO studies conducted over the past 40 years. This analysis shows considerable heterogeneity among CNO studies regarding participant selection, the amount consumed, and the study duration. The analysis reveals that, overall, CNO consumption gives variable TChol and LDL-C values, but that the HDL-cholesterol (HDL-C) values increase and triglycerides (TG) decrease. This holistic lipid assessment, together with the consideration of lipid ratios, shows that CNO does not pose a health risk for heart disease. Because the predominantly medium-chain fatty acid profile of CNO is significantly different from that of lard and palm oil, studies using these as reference materials do not apply to CNO. This paper concludes that the recommendation to avoid consuming coconut oil due to the risk of heart disease is not justified.

Impact of Coconut Oil and Its Bioactive Metabolites in Alzheimer's Disease and Dementia: A Systematic Review and Meta-Analysis

Background/Objectives: Alzheimer's disease (AD) is the most common form of dementia and affects approximately 50 million individuals worldwide. Interest in coconut oil (CO) as a potential dietary intervention has surged owing to its substantial medium-chain triglyceride (MCT) content. Therefore, sustaining cognitive function and potentially slowing the progression of AD are crucial. This systematic review and meta-analysis evaluated the effects of CO and its bioactive metabolites on AD and dementia. Methods: The review protocol is registered in PROSPERO (CRD42023450435). Relevant research articles published between January 2015 and June 2023 were systematically searched. Seven studies met the predetermined eligibility criteria. Thematic analysis was utilized to synthesis the data about the qualitative features, while meta-analysis was employed for the quantitative findings. A meta-analysis was conducted to assess the standardized mean difference (SMD) and the corresponding 95% confidence interval (CI). Forest plots were generated using Review Manager 5.3 (RevMan 5.3). Results: The analysis revealed that all studies showed consistent results regarding the effects of CO on cognitive scores, with little variability in the true effects of CO on cognitive scores across the studies included in the meta-analysis. Conclusions: CO improved cognitive scores in patients with AD compared with those in the control group (p < 0.05). The results of this study add to the increasing amount of evidence indicating that MCTs found in CO might be a way to improve abilities and potentially slow the advancement of AD. The findings of this study may encourage the development of targeted dietary strategies and interventions for individuals at risk of or diagnosed with AD.

The Lipid-Heart Hypothesis and the Keys Equation Defined the Dietary Guidelines but Ignored the Impact of Trans-Fat and High Linoleic Acid Consumption

In response to a perceived epidemic of coronary heart disease, Ancel Keys introduced the lipid-heart hypothesis in 1953 which asserted that high intakes of total fat, saturated fat, and cholesterol lead to atherosclerosis and that consuming less fat and cholesterol, and replacing saturated fat with polyunsaturated fat, would reduce serum cholesterol and consequently the risk of heart disease. Keys proposed an equation that would predict the concentration of serum cholesterol (ΔChol.) from the consumption of saturated fat (ΔS), polyunsaturated fat (ΔP), and cholesterol (ΔZ): ΔChol. = 1.2(2ΔS - ΔP) + 1.5ΔZ. However, the Keys equation conflated natural saturated fat and industrial trans-fat into a single parameter and considered only linoleic acid as the polyunsaturated fat. This ignored the widespread consumption of trans-fat and its effects on serum cholesterol and promoted an imbalance of omega-6 to omega-3 fatty acids in the diet. Numerous observational, epidemiological, interventional, and autopsy studies have failed to validate the Keys equation and the lipid-heart hypothesis. Nevertheless, these have been the cornerstone of national and international dietary guidelines which have focused disproportionately on heart disease and much less so on cancer and metabolic disorders, which have steadily increased since the adoption of this hypothesis.

Ketogenic Approaches for the Treatment of Alzheimer's Disease

Dementia represents one of the largest and most urgent public health problems across the globe. Modeling projections have estimated that delaying the onset of Alzheimer's disease (AD) by 6 months would reduce the prevalence by 5%, while a delay of 12 months would reduce the prevalence by 10%. One approach to achieving a delay in the onset of AD is to investigate lifestyle interventions that could be widely implemented with a favorable risk-benefit relationship and socioeconomic profile. Amongst such interventions, there is increasing evidence to support the use of ketogenic interventions in AD. Indeed, it is well known that cerebral glucose metabolism is impaired in AD, even at a preclinical stage, and a growing body of literature suggests that these findings may represent a primary pathogenic mechanism leading to neurodegeneration. Ketones are readily taken up by the brain and can serve as an alternative energy source for neurons and glia, hypothetically bypassing the glucose uptake deficit in AD. In this invited review we discuss the preclinical as well as clinical work aiming to increase ketones as a primary intervention in AD, including variations of the ketogenic diet, medium chain triglyceride supplementation, and newer, more experimental approaches.