Can the dietary fat type facilitate memory impairments in adulthood? A comparative study between Mediterranean and Western-based diet in rats

The association between dietary intake of fats and transient global amnesia (TGA)

BACKGROUND

Different types of dietary fat may influence memory and cognitive functions. This study aimed to investigate the association between dietary fat intake and transient global amnesia (TGA).

METHODS

This case-control study was conducted using Persian Sabzevar cohort data on 258 individuals with TGA and 520 individuals without amnesia in Sabzevar Iran. The food frequency questionnaire (FFQ) was used to assess the intake of dietary fats of the participants. All study participants were screened for TGA by a neurologist and their status was determined based on the diagnostic symptoms defined by the Kaplan and Hodges criteria.

RESULTS

There was an inverse association between the risk of TGA and dietary intake of alpha-linolenic acid (ALA) (OR = 0.94, CI95%:0.88-0.99, P = 0.01). Also, a positive association was observed between TGA and dietary intake of n-6 fatty acids (OR = 1.18, CI 95%: 1.04-1.33, P = 0.01). The results remained significant after adjustment for age, sex, education, job, marital status, physical activity, BMI, and calorie intake.

CONCLUSION

Omega-3 fatty acids may have beneficial effects; however, omega-6 fatty acids may have adverse effects on the risk of amnesia. Further longitudinal studies are warranted.

Early exposure to trans fat causes cognitive impairment by modulating the expression of proteins associated with oxidative stress and synaptic plasticity in Drosophila melanogaster

Evidence has shown that consuming trans fatty acids (TFA) during development leads to their incorporation into the nervous tissue, resulting in neurological changes in flies. In this study, Drosophila melanogaster was exposed to different concentrations of hydrogenated vegetable fat (HVF) during development: substitute hydrogenated vegetable fat (SHVF), HVF 10 %, and HVF 20 %. The objective was to evaluate the effects of early trans fat exposure on cognition and associated pathways in flies. The results showed that early TFA exposure provoked a cerebral redox imbalance, as confirmed by increased reactive species (HVF 10 and 20 %) and lipid peroxidation (SHVF, HVF 10, and 20 %), reduced nuclear factor erythroid 2-related factor 2 immunoreactivity (HVF 10 and 20 %), and increased heat shock protein 70 (HVF 20 %), which was possibly responsible for decreasing superoxide dismutase (SHVF, HVF 10, and 20 %) and catalase (HVF 20 %) activities. Furthermore, the presence of TFA in nervous tissue impaired learning (HVF 10 and 20 %) and memory at 6 and 24 h (SHVF, HVF 10, and 20 %). These cognitive impairments may be linked to reduced Shank levels (HVF 20 %) and increased acetylcholinesterase activity (SHVF, HVF 10 and 20 %) observed. Our findings demonstrate that early exposure to trans fat leads to cerebral redox imbalance, altering proteins associated with stress, synaptic plasticity, and the cholinergic system, consequently leading to cognitive impairment in flies.

Advances in free fatty acid profiles in gestational diabetes mellitus

The morbidity of gestational diabetes mellitus (GDM) is increasing and is associated with adverse perinatal outcomes and long-term maternal and infant health. The exact mechanism underlying changes in plasma free fatty acid (FFA) profiles in patients with GDM is unknown. However, it is believed that changes in diet and lipid metabolism may play a role. Fatty acids contain many specific FFAs, and the type of FFA has different impacts on physiological processes; hence, determining changes in FFAs in individual plasma is essential. Alterations in FFA concentration or profile may facilitate insulin resistance. Additionally, some FFAs show potential to predict GDM in early pregnancy and are strongly associated with the growth and development of the fetus and occurrence of macrosomia. Here, we aimed to review changes in FFAs in women with GDM and discuss the relationship of FFAs with GDM incidence and adverse outcomes.

Gut-brain communication mediates the impact of dietary lipids on cognitive capacity

Cognitive impairment, as a prevalent symptom of nervous system disorders, poses one of the most challenging aspects in the management of brain diseases. Lipids present in the cell membranes of all neurons within the brain and dietary lipids can regulate the cognition and memory function. In recent years, the advancements in gut microbiome research have enabled the exploration of dietary lipids targeting the gut-brain axis as a strategy for regulating cognition. This present review provides an in-depth overview of how lipids modulate cognition via the gut-brain axis depending on metabolic, immune, neural and endocrine pathways. It also comprehensively analyzes the effects of diverse lipids on the gut microbiota and intestinal barrier function, thereby affecting the central nervous system and cognitive capacity. Moreover, comparative analysis of the positive and negative effects is presented between beneficial and detrimental lipids. The former encompass monounsaturated fatty acids, short-chain fatty acids, omega-3 polyunsaturated fatty acids, phospholipids, phytosterols, fungal sterols and bioactive lipid-soluble vitamins, as well as lipid-derived gut metabolites, whereas the latter (detrimental lipids) include medium- or long-chain fatty acids, excessive proportions of n-6 polyunsaturated fatty acids, industrial trans fatty acids, and zoosterols. To sum up, the focus of this review is on how gut-brain communication mediates the impact of dietary lipids on cognitive capacity, providing a novel theoretical foundation for promoting brain cognitive health and scientific lipid consumption patterns.

Diet quality indices and changes in cognition during chemotherapy

PURPOSE

No evidence-based prevention strategies currently exist for cancer-related cognitive decline (CRCD). Although patients are often advised to engage in healthy lifestyle activities (e.g., nutritious diet), little is known about the impact of diet on preventing CRCD. This secondary analysis evaluated the association of pre-treatment diet quality indices on change in self-reported cognition during chemotherapy.

METHODS

Study participants (n = 96) completed the Block Brief Food Frequency Questionnaire (FFQ) before receiving their first infusion and the PROMIS cognitive function and cognitive abilities questionnaires before infusion and again 5 days later (i.e., when symptoms were expected to be their worst). Diet quality indices included the Dietary Approaches to Stop Hypertension (DASH), Alternate Mediterranean Diet (aMED), and a low carbohydrate diet index and their components. Descriptive statistics were generated for demographic and clinical variables and diet indices. Residualized change models were computed to examine whether diet was associated with change in cognitive function and cognitive abilities, controlling for age, sex, cancer type, treatment type, depression, and fatigue.

RESULTS

Study participants had a mean age of 59 ± 10.8 years and 69% were female. Although total diet index scores did not predict change in cognitive function or cognitive abilities, higher pre-treatment ratio of aMED monounsaturated/saturated fat was associated with less decline in cognitive function and cognitive abilities at 5-day post-infusion (P ≤ .001).

CONCLUSIONS

Higher pre-treatment ratio of monounsaturated/saturated fat intake was associated with less CRCD early in chemotherapy. Results suggest greater monounsaturated fat and less saturated fat intake could be protective against CRCD during chemotherapy.

INTERESTERIFIED FAT MATERNAL CONSUMPTION BEFORE CONCEPTION PROGRAMMS MEMORY AND LEARNING OF ADULTHOOD OFFSPRING: how big is this deleterious repercussion?

In recent years, interesterified fat (IF) has largely replaced trans fat in industrialized food. Studies of our research group showed that IF consumption may not be safe for central nervous system (CNS) functions. Our current aim was to evaluate IF maternal consumption before conception on cognitive performance of adult rat offspring. Female Wistar rats were fed with standard chow plus 20% soybean and fish oil mix (control group) or plus 20% IF from weaning until adulthood (before mating), when the diets were replaced by standard chow only. Following the gestation and pups' development, locomotion and memory performance followed by neurotrophin immunocontent and fatty acids (FA) profile in the hippocampus of the adulthood male offspring were quantified. Maternal IF consumption before conception decreased hippocampal palmitoleic acid incorporation, proBDNF and BDNF levels, decreasing both exploratory activity and memory performance in adult offspring. Considering that, the adult male offspring did not consume IF directly, further studies are needed to understand the molecular mechanisms and if the IF maternal preconception consumption could induce the epigenetic changes observed here. Our outcomes reinforce an immediate necessity to monitor and / or question the replacement of trans fat by IF with further studies involving CNS functions.

Dietary fatty acids affect learning and memory ability via regulating inflammatory factors in obese mice

OBJECTIVE

High-fat diets are linked to obesity, contributing to the alterations in inflammatory signaling pathways, which is associated with cognitive function. We aim to investigate the mechanisms by which various different types of dietary fatty acids affecting cognitive function in obese mice through the gut/brain axis-inflammatory signaling pathway.

METHODS AND RESULTS

Eight-week-old male C57BL/6 mice were fed with basal diet (control group), lard high-fat diet (containing long-chain saturated fatty acid (LCSFA group)), coconut oil high-fat diet (containing medium-chain saturated fatty acid (MCSFA group)), linseed oil high-fat diet (containing n-3 polyunsaturated fatty acid (n-3 PUFA group)), soybean oil high-fat diet (containing n-6 polyunsaturated fatty acid (n-6 PUFA group)), olive oil high-fat diet (containing monounsaturated fatty acid (MUFA group)) and 8% hydrogenated soybean oil high-fat diet (containing trans fatty acid (TFA group)) respectively for 16 weeks. Our results revealed that the mean escape latency was significantly prolonged in LCSFA group, and the latency to cross the platform location of n-6 PUFA and TFA groups were increased significantly. The differences of inflammatory markers and toll-like receptor-myeloid differentiation factor-88-nuclear factor kappa-B (TLR-MyD88-NF-κB) inflammatory signaling pathway expressions among all groups reached statistical significances.

CONCLUSION

Compared to basal diet, high-fat diets enriched in LCSFA, MCSFA, n-6 PUFA, MUFA, and TFA might exert detrimental effects on cognitive function in obese mice via regulating the inflammatory markers and inflammatory signaling pathway in brain and intestine. High-fat diet enriched in n-3 PUFA might exhibit different effect on modulating inflammatory responses in different tissues and might benefit to cognitive function.

Interesterified fat consumption since gestation decreases striatal dopaminergic targets levels and gdnf impairing locomotion of adult offspring

Interesterified fat (IF) currently substitutes the hydrogenated vegetable fat (HVF) in processed foods. However, the IF consumption impact on the central nervous system (CNS) has been poorly studied. The current study investigated connections between IF chronic consumption and locomotor impairments in early life period and adulthood of rats and access brain molecular targets related to behavior changes in adulthood offspring. During pregnancy and lactation, female rats received soybean oil (SO) or IF and their male pups received the same maternal supplementation from weaning until adulthood. Pups' motor ability and locomotor activity in adulthood were evaluated. In the adult offspring striatum, dopaminergic targets, glial cell line-derived neurotrophic factor (GDFN) and lipid profile were quantified. Pups from IF supplementation group presented impaired learning concerning complex motor skill and sensorimotor behavior. The same animals showed decreased locomotion in adulthood. Moreover, IF group showed decreased immunoreactivity of all dopaminergic targets evaluated and GDNF, along with important changes in FA composition in striatum. This study shows that the brain modifications induce by IF consumption resulted in impaired motor control in pups and decreased locomotion in adult animals. Other studies about health damages induced by IF consumption may have a contribution from our current outcomes.

Addition of Saturated and Trans-fatty Acids to the Diet Induces Depressive and Anxiety-like Behaviors in Drosophila melanogaster

This study aimed to evaluate the effects of the addition of saturated fat and hydrogenated vegetable fat (HVF) to the diet on depressive and anxiety-like behaviors in Drosophila melanogaster. Flies were exposed to experimental diets: regular diet (RD), or HVF in the concentrations of the substitute (SHVF), HVF 10% and HVF 20%, or Lard (L) in the concentrations of the substitute (SL), L 10% and L 20%, during seven days. Our results showed that flies fed with the HVF diet presented similar behaviors to depression, anxiety, and a higher number of aggressive events. Flies exposed to L showed only depressive-like behavior. Regarding serotonin levels (5HT), there was a significant reduction in the flies exposed to SHVF, HVF 10%, HVF 20%, and L 20%. Regarding the levels of octopamine (OA), there was a significant reduction in the flies exposed to both HVF and L rich diets when compared with the RD group. Also, there was a significant negative correlation between 5HT or OA levels and behaviors of aggressiveness, negative geotaxis, immobility time, light/dark, and grooming in the flies. This study shows that D. melanogaster can serve as a valuable model for understanding psychiatric disorders and that the type of fatty acid (FA) offered in the diet can influence these disorders. This demonstrates the importance of the composition of the FAs in the neural pathways, being able to influence the signaling of neurotransmitters, such as 5HT and OA, and thus, cause behavioral changes.

Determining sample size adequacy for animal model studies in nutrition research: limits and ethical challenges of ordinary power calculation procedures

Animal models are widely used in the field of nutrition research. Scientifically and ethically sound experiments need an adequate number of experimental units. The use of 5-10 units is common, but such sample sizes can be justified for large effect sizes only. We reviewed animal model studies recently published in selected journals in the field of nutrition sciences. We performed a simulation study aimed at determining the adequate sample size for normality assessment. We then performed power calculations for a number of statistical tests commonly found in rodent model studies in nutrition research. Among the selected papers, sample sizes ranged from 6-18 units per group. None of them justified the sample size. However, such sample sizes do not allow for normality testing, thus, graphical approaches should be used. Parametric approaches result in higher statistical power when compared to their non-parametric counterparts. Repeated measures analysis should always be preferred, when possible.