A mind cleared by walnut oil: The effects of polyunsaturated and saturated fat on extinction learning

The EAT-Lancet reference diet and cognitive function across the life course

The EAT-Lancet Commission devised a sustainable reference diet with the aim of reducing the incidence of non-communicable diseases and mortality globally while improving food system sustainability. The extent to which the reference diet supports cognitive function across the life course, however, has not yet been evaluated. This Review assesses the evidence for diet supporting cognitive function from childhood into old age. A comprehensive but non-exhaustive literature search was done, synthesising studies that investigated the effect of whole foods on cognition in healthy, community-dwelling human participants. We found that the current evidence base is weak with mixed conclusions and multiple methodological caveats, which precludes strong conclusions pertaining to the suitability of dietary recommendations for each food group per age group. Long-term intervention and prospective cohort studies are needed to reduce this knowledge deficit. Revising dietary recommendations with the aim of maintaining an adequate nutrient intake to sustain healthy cognitive function across the life course could be worthwhile. This Review outlines recommendations for future work to help improve the current knowledge deficit regarding dietary intake and cognitive function across the life course and its implications for dietary guidelines such as the EAT-Lancet Commission.

Walnut intake, cognitive outcomes and risk factors: a systematic review and meta-analysis

BACKGROUND

Walnuts contain nutrients that are associated with improved cognitive health. To our knowledge, no review has systematically examined the effects of walnuts on cognitive function and risk for cognitive decline.

OBJECTIVE

To conduct a systematic review and meta-analysis evaluating the effects of walnut intake on cognition-related outcomes and risk-factors for cognitive decline in adults.

METHODS

Medline®, Commonwealth Agricultural Bureau, and Cochrane Central Register of Controlled Trials were searched for randomized controlled trials (RCTs) and observational studies published until April 2020 on walnut intake, cognition (e.g. cognitive function, stroke, and mood), and selected risk factors for cognitive decline (e.g. glucose homeostasis and inflammation). Risk-of-bias and strength-of-evidence assessments were conducted using standard validated tools. Random-effects meta-analyses were conducted when ≥3 studies reported quantitative data for each outcome.

RESULTS

32 RCT and 7 observational study publications were included. Meta-analysis of cognition-related outcomes could not be conducted due to heterogeneity of tests. None of the 5 cognition RCTs found significant effects of walnuts on overall cognition, although 3 studies found improvements on subdomains and/or subgroups. All 7 observational studies found significant associations and a dose-response relationship between walnut intake and cognition-related outcomes. Meta-analyses of 27 RCTs reporting glucose homeostasis and inflammation outcomes, selected risk factors for cognitive decline, did not show significant effects of walnut intake.

CONCLUSIONS

Due to the non-uniformity of tests for cognition-related outcomes, definitive conclusions regarding the effect of walnut consumption on cognition could not be reached. Additionally, evidence does not show associations between walnut intake and glucose homeostasis or inflammation, cognitive decline risk-factors. High-quality studies with standardized measures are needed to clarify the role of walnuts in cognitive health.KEY MESSAGESThis is a systematic review and meta-analysis of 5 randomized clinical trials and 7 observational study articles of the impact of walnut intake on cognition decline and 27 randomized clinical trials of the effect of walnut intake on risk factors for cognitive decline including glucose homeostasis and inflammation.The non-uniformity of tests performed to measure cognitive function in the various studies did not allow for a meta-analysis of these studies. A definitive conclusion could therefore not be reached regarding the effect of walnut intake on cognitive decline.The evidence available does not show an association between walnut intake and glucose homeostasis or inflammation.

Perilla Oil and Bifidobacterium for Alleviating Fear of Cancer Recurrence in Breast Cancer Survivors: Study Protocol for a Three-Arm Phase II Randomized Controlled Study (POB Study)

The fear of cancer recurrence (FCR) is the most common and most severe unmet need among cancer survivors. Safe treatments for the FCR that are easily disseminated are greatly needed. Our primary aim is a preliminary evaluation of the efficacy and effect size of perilla oil, which is rich in omega-3 fatty acids, and Bifidobacterium, a probiotic, on FCR in breast cancer survivors after the completion of chemotherapy. This study has been planned as an exploratory clinical study (phase II) and will be conducted as a three-arm, 12-week parallel group, masked-rater randomized controlled trial. Fifteen participants will be randomized with 1:1:1 allocation to receive Bifidobacterium plus perilla oil, Bifidobacterium alone, or no intervention (control). Interventions will end within 12 weeks after the random allocation of each participant. The participants will be outpatients with invasive breast cancer aged 20 years or older whose chemotherapy was completed at least 6 months before registration; hormone therapy may be ongoing. The primary outcome will be severity of FCR at 12 weeks assessed by masked raters using the 4-item Concerns about Recurrence Scale concerning overall fear of recurrence. The study protocol for the current study is registered in the Japan Registry of Clinical Trials (jRCTs031200029).

Health Benefits of Nut Consumption in Middle-Aged and Elderly Population

Aging is considered the major risk factor for most chronic disorders. Oxidative stress and chronic inflammation are two major contributors for cellular senescence, downregulation of stress response pathways with a decrease of protective cellular activity and accumulation of cellular damage, leading in time to age-related diseases. This review investigated the most recent clinical trials and cohort studies published in the last ten years, which presented the influence of tree nut and peanut antioxidant diets in preventing or delaying age-related diseases in middle-aged and elderly subjects (≥55 years old). Tree nut and peanut ingestion has the possibility to influence blood lipid count, biochemical and anthropometric parameters, endothelial function and inflammatory biomarkers, thereby positively affecting cardiometabolic morbidity and mortality, cancers, and cognitive disorders, mainly through the nuts' healthy lipid profile and antioxidant and anti-inflammatory mechanisms of actions. Clinical evidence and scientific findings demonstrate the importance of diets characterized by a high intake of nuts and emphasize their potential in preventing age-related diseases, validating the addition of tree nuts and peanuts in the diet of older adults. Therefore, increased consumption of bioactive antioxidant compounds from nuts clearly impacts many risk factors related to aging and can extend health span and lifespan.

Fear of cancer recurrence among breast cancer survivors could be controlled by prudent dietary modification with polyunsaturated fatty acids

BACKGROUND

The pathophysiology of fear of cancer recurrence (FCR), the leading unmet psychological need of cancer survivors, may involve the dysfunctional processing of fear memory. n-3 polyunsaturated fatty acids (PUFAs) have beneficial effects on psychiatric disorders, including depressive disorder and anxiety disorders, and are involved in fear memory processing. We hypothesized that n-3 PUFA composition is associated with FCR in cancer survivors.

METHODS

We conducted a cross-sectional study to examine the relationship between n-3 PUFAs and FCR among breast cancer survivors. Adults who had been diagnosed with invasive breast cancer and were not undergoing chemotherapy were asked to participate. Blood PUFA composition was evaluated by using capillary blood. We directly administered the Concerns About Recurrence Scale (CARS) to assess the grade of FCR.

RESULTS

Among 126 participants used for the analysis, the mean age (SD) was 58 (11) years and 47% had stage I cancer. Multiple regression analysis controlling for possible confounders, depressive symptoms, and post-traumatic stress disorder (PTSD) symptoms revealed that the alpha-linolenic acid (ALA) level was significantly inversely associated with the average score on the CARS overall fear index (beta = -0.165, p = 0.04). No significant associations were found for other PUFAs.

LIMITATIONS

Our findings were obtained from a cross-sectional study in a single institute.

CONCLUSION

These findings provide the first evidence of a beneficial effect of ALA on FCR and indicate the need for prospective study of this association. FCR among breast cancer survivors might be controllable by prudent selection of ALA-containing cooking oil.