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A combined DHA-rich fish oil and cocoa flavanols intervention does not improve cognition or brain structure in older adults with memory complaints: results from the CANN randomized, controlled parallel-design study.
Vauzour, D, Scholey, A, White, DJ, Cohen, NJ, Cassidy, A, Gillings, R, Irvine, MA, Kay, CD, Kim, M, King, R, et al
The American journal of clinical nutrition. 2023;118(2):369-381
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At a population level, interventions that delay the onset of dementia by 2 years are predicted to reduce the number of dementia patients by 20%. Prospective cohort studies have consistently reported cognitive and neurophysiological benefits of the fish-derived omega-3 long-chain polyunsaturated fatty acids (PUFAs), EPA, and DHA and plant-derived flavanols (FLAVs). This study hypothesised that 12-month administration of a combination of 500 mg cocoa FLAVs with 1.5g omega-3 long-chain PUFAs would improve cognitive function in a mixed subjective cognitive impairment and mild cognitive impairment cohort. This study is based on the results of the CANN randomised controlled trial. A total of 258 participants were recruited and randomised to control or test intervention. Following baseline measurements, 125 participants were randomised into the active OM3FLAV intervention group and 121 into the control group. Results showed that the 1-year intervention with EPA and DHA and cocoa FLAVs did not improve cognition or protect the brain against atrophy in older adults with evidence of memory deficits. Authors concluded that given the complexity of neuropathological processes underpinning cognitive decline and dementia risk, multidomain, multinutrient, or whole diet approaches may be needed to positively impact the cognitive trajectory in the medium term (months to 3 years).
Abstract
BACKGROUND There is evidence that both omega-3 long-chain polyunsaturated fatty acids (PUFAs) (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) and cocoa flavanols can improve cognitive performance in both healthy individuals and in those with memory complaints. However, their combined effect is unknown. OBJECTIVES To investigate the combined effect of EPA/DHA and cocoa flavanols (OM3FLAV) on cognitive performance and brain structures in older adults with memory complaints. METHODS A randomized placebo-controlled trial of DHA-rich fish oil (providing 1.1 g/d DHA and 0.4 g/d EPA) and a flavanol-rich dark chocolate (providing 500 mg/d flavan-3-ols) was conducted in 259 older adults with either subjective cognitive impairment or mild cognitive impairment. Participants underwent assessment at baseline, 3 mo, and 12 mo. The primary outcome was the number of false-positives on a picture recognition task from the Cognitive Drug Research computerized assessment battery. Secondary outcomes included other cognition and mood outcomes, plasma lipids, brain-derived neurotrophic factor (BDNF), and glucose levels. A subset of 110 participants underwent structural neuroimaging at baseline and at 12 mo. RESULTS 197 participants completed the study. The combined intervention had no significant effect on any cognitive outcomes, with the exception of reaction time variability (P = 0.007), alertness (P < 0.001), and executive function (P < 0.001), with a decline in function observed in the OM3FLAV group (118.6 [SD 25.3] at baseline versus 113.3 [SD 25.4] at 12 mo for executive function) relative to the control, and an associated decrease in cortical volume (P = 0.039). Compared with the control group, OM3FLAV increased plasma HDL, total cholesterol ratio (P < 0.001), and glucose (P = 0.008) and reduced TG concentrations (P < 0.001) by 3 mo, which were sustained to 12 mo, with no effect on BDNF. Changes in plasma EPA and DHA and urinary flavonoid metabolite concentrations confirmed compliance to the intervention. CONCLUSIONS These results suggest that cosupplementation with ω-3 PUFAs and cocoa flavanols for 12 mo does not improve cognitive outcomes in those with cognitive impairment. This trial was registered at clinicaltrials.gov as NCT02525198.
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Impact of α-Linolenic Acid, the Vegetable ω-3 Fatty Acid, on Cardiovascular Disease and Cognition.
Sala-Vila, A, Fleming, J, Kris-Etherton, P, Ros, E
Advances in nutrition (Bethesda, Md.). 2022;13(5):1584-1602
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α-Linolenic acid (ALA) is an omega-3 fatty acid found in seeds and nuts such as flaxseeds, chia seeds, and walnuts and in oils such as canola oil, soybean oil, flaxseed oil and walnut oil. It has been shown to reduce the risk of coronary heart disease and cardiovascular disease. This meta-analysis examined the results of various studies, including epidemiologic studies, randomized controlled trials, and systematic reviews, to evaluate the beneficial effects of ALA in improving cognitive function and reducing the risk of cardiovascular disease and coronary heart disease. The included studies showed a correlation between ALA intake and a decreased risk of cardiovascular disease and coronary heart disease, possibly due to ALA's anti-inflammatory properties, as well as its ability to reduce total cholesterol, LDL cholesterol, triglycerides, and blood pressure. The analysis also found that ALA intake may reduce the risk of type 2 diabetes and cognitive impairment. Healthcare professionals can leverage the findings of this analysis to educate individuals about the benefits of dietary ALA in improving cardiovascular and cognitive outcomes. However, further studies are necessary to establish definitive conclusions and determine therapeutic dosage.
Abstract
Given the evidence of the health benefits of plant-based diets and long-chain n-3 (ω-3) fatty acids, there is keen interest in better understanding the role of α-linolenic acid (ALA), a plant-derived n-3 fatty acid, on cardiometabolic diseases and cognition. There is increasing evidence for ALA largely based on its major food sources (i.e., walnuts and flaxseed); however, this lags behind our understanding of long-chain n-3 fatty acids. Meta-analyses of observational studies have shown that increasing dietary ALA is associated with a 10% lower risk of total cardiovascular disease and a 20% reduced risk of fatal coronary heart disease. Three randomized controlled trials (RCTs) [AlphaOmega trial, Prevención con Dieta Mediterránea (PREDIMED) trial, and Lyon Diet Heart Study] all showed benefits of diets high in ALA on cardiovascular-related outcomes, but the AlphaOmega trial, designed to specifically evaluate ALA effects, only showed a trend for benefit. RCTs have shown that dietary ALA reduced total cholesterol, LDL cholesterol, triglycerides, and blood pressure, and epidemiologic studies and some trials also have shown an anti-inflammatory effect of ALA, which collectively account for, in part, the cardiovascular benefits of ALA. A meta-analysis reported a trend toward diabetes risk reduction with both dietary and biomarker ALA. For metabolic syndrome and obesity, the evidence for ALA benefits is inconclusive. The role of ALA in cognition is in the early stages but shows promising evidence of counteracting cognitive impairment. Much has been learned about the health benefits of ALA and with additional research we will be better positioned to make strong evidence-based dietary recommendations for the reduction of many chronic diseases.
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Nutrition to Prevent or Treat Cognitive Impairment in Older Adults: A GRADE Recommendation.
Buckinx, F, Aubertin-Leheudre, M
The journal of prevention of Alzheimer's disease. 2021;8(1):110-116
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Cognitive impairment is a public health problem due to its increasing prevalence in the aging population. Despite pharmacological advances, there are not yet effective treatments to delay or reverse cognitive impairment. Moreover, there is limited knowledge of Alzheimer disease modifiable risk factors namely nutrition. The aim of this review was to grade, classify and provide recommendations for the preferred diet to prevent or to treat cognitive impairment. This review shows that: - some nutritional factors appear to either increase the risk of cognitive decline or protect against it. - risk could be conferred by diets high in milk and dairy products whereas some protection can be offered by adhering to a Mediterranean diet to decrease the risk of cognitive decline. - it is important to follow a diet rich in mono- and poly- unsaturated fatty acids, fruit and vegetable, vitamin D and low in saturated fatty acids. Authors conclude that diet is an important modifiable factor to prevent or protect against cognitive decline.
Abstract
Aging is associated with cognitive declines leading to mild cognitive impairments or Alzheimer disease. Nutrition appear to protect from aging. Some dietary factors could either increase or protect against cognitive declines. This article aimed to provide GRADE recommendations related to nutrition aspects able to prevent or to treat cognitive impairments. A comprehensive literature review was performed using Medline database. The GRADE approach was used to classify quality of the existing evidence (systematic review or meta-analysis).The GRADE process led us to formulate seven key nutritional recommendations to manage cognitive declines, but did not allow us to do it for protein, vitamin B or antioxidants. Thus, 1) adherence to a Mediterranean diet (GRADE 1B); 2) high-level of consumption of mono- or poly- unsaturated fatty acids combined to a low consumption of saturated fatty acids (GRADE 1B); 3) high consumption of fruits and vegetables (GRADE 1B); 4) higher vitamin D intake (GRADE 1C) than the recommended daily allowance. In addition, a ketogenic diet, a low consumption of whole-fat dairy products or a caloric restriction are promising nutritional habits although the evidence does not yet support widespread uptake (GRADE 2C). In conclusion, nutrition is an important modifiable factor to prevent or protect against cognitive decline. Nevertheless, more studies are required to determine specific guidelines such as duration and amounts of nutrients to help older adult to maintain a healthy cognitive life.