Tag: Mediterranean Diet

Mediterranean diet linked to richer gut diversity, study finds
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In a recent study published in the journal Nutrients, researchers explored how following the Mediterranean diet (MD) influences the gut microbiome of healthy individuals through a well-defined cohort study.

Their results indicate that adhering to MD increases the species diversity of microbiota, offering insights into how it can lead to measurable health benefits.

Study: Impact of the Mediterranean Diet on the Gut Microbiome of a Well-Defined Cohort of Healthy Individuals. Image Credit: Marian Weyo / Shutterstock

Background

Traditionally followed by many Mediterranean coastal communities, MD is a nutrient-rich diet dominated by whole grains, healthy fats, fruits, and vegetables with antioxidant and anti-inflammatory properties.

It has been associated with improved cardiovascular health and reductions in the risk of metabolic syndrome, neurogenerative disorders, type 2 diabetes, and some cancers. This is in contrast with diets high in refined carbohydrates and fats, which have been implicated in increases in obesity and multiple metabolic disorders.

The effect of different diets may be mediated by how they influence the gut microbiome, which plays a crucial role in disease prevention and maintaining health. Certain dietary habits and food components associated with MD may strengthen beneficial gut microbiota, as dietary diversity, fat composition, and fiber intake all leave distinct marks on microbial communities.

About the study

In this study, researchers recruited healthy volunteers (donors and relatives) from a fecal transplant clinic in Spain. Participating individuals had a body mass index (BMI) between 17 and 30, no known diseases or disorders, did not drink more than 50g of alcohol per day, and had not taken vaccines and specified medications in the three months preceding the study.

Participants were stratified by age and provided demographic information, dietary intake through a food-frequency questionnaire, and medical history. Their adherence to the MD was assessed using a dietary quality index; those receiving a score of 1-4 were classified as having ‘good’ adherence, while those scoring 5-9 had ‘medium’ adherence.

The gut microbiome was assessed by analyzing stool samples, identifying microbe species, and measuring species richness, the number of species found in a sample, and species evenness (Pielou index), which measures uniformity or similarity in the abundance of different species.

The inverse Simpson index was used to indicate richness in communities with the same evenness, while the Shannon index examined how many species lived in a given habitat and their relative abundances.

The alpha diversity, which measures species diversity within a single individual, and beta diversity, which assesses diversity differences among individuals, were also calculated. Researchers also calculated correlations between microbial abundance and nutrient intake.

Findings

Of the 60 individuals enrolled in the study, slightly over 50% were female, and the median age was 31. On average, females showed more species richness and higher values for the Pielou, inverse Simpson, and Shannon indexes.

Firmicutes, Bacteroidetes, and Actinobacteria, were the dominant phyla in males and females. Abundant genera included Bifidobacterium, Bacteroides, Faecalibacterium, Prevotella, and Blautia. While Bacteroides were abundant across all age groups, Bifidobacterium became less dominant with age.

Across all diversity indices, children showed consistently lower values than other groups. Teenagers had the highest richness values, while older adults (49 years old and above) had higher Pielou, Shannon, and inverse Simpson values. Stratifying these results by sex showed that these differences remained for males but not females, except for species evenness, which persisted for both.

The median diet adherence score for the 39 individuals who completed the food-frequency questionnaires was 5. People with good adherence had a median age of 48, while those with medium adherence were younger, with a median age of 30.

Better MD adherence was associated with having higher Bacteroides and Paraprevotella abundance, but there were no sex-based differences in alpha and beta diversity indices. Stratifying by age, the researchers found that good adherence decreased the abundance of different genera for different groups.

Correlation analysis showed that fat intake was negatively associated with the Shannon index, while non-starch polysaccharides (NSPs) and total sugars were positively associated. The Pielou index showed a negative association with red meat intake while directly correlating with total sugars and NSPs.

People with better adherence also showed differences in pathways related to bladder cancer, polycyclic aromatic hydrocarbon degradation, and vasopressin-regulated water reabsorption. They showed more enzymes related to lipid metabolism and different biosynthesis processes.

Conclusions

This study assessed MD influence on gut microbiota through a well-defined cohort based on sex and age, finding significant differences in microbial composition as well as alpha and beta diversity associated with adherence. These findings were strengthened by the identification of functional pathways and specific bacterial taxa that differed based on adherence levels.

The small sample study size may limit the generalizability of these findings; further studies using longitudinal designs and larger cohorts are needed to better understand how MD can strengthen the microbiome and boost health outcomes.
Journal reference:

Impact of the Mediterranean diet on the gut microbiome of a well-defined cohort of healthy individuals. Vázquez-Cuesta, S., García, N.L., Rodríguez-Fernández, S., Fernández-Avila, A.I., Bermejo, J., Fernández-Avilés, F., Muñoz, P., Bouza, E., Reigadas, E. Nutrients (2024). DOI: 10.3390/nu16060793, https://www.mdpi.com/2072-6643/16/6/793
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March 13, 2024
Mediterranean diet’s aromatic herbs lower blood sugar
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In a recent study published in the journal Nutrients, researchers from Spain investigated the influence of aromatic herbs and spices in the Mediterranean diet (MedDiet) on the glycemic profiles of patients with type 2 diabetes mellitus (T2DM). They found that black cumin, cinnamon, ginger, curcumin, and saffron significantly lowered fasting blood glucose levels. Further, they found that black cumin and ginger significantly improved glycated hemoglobin (HbA1c) levels in T2DM patients, while cinnamon and ginger significantly lowered insulin concentration.

Review: Changes in food preferences and ingestive behaviors after glucagon-like peptide-1 analog treatment: techniques and opportunities. Image Credit: aboikis / Shutterstock

Background

T2DM is a critical healthcare concern, affecting 460 million people globally. Its prevalence has surged in the past four decades, contributing to three or more comorbidities in 60% of patients ten years after diagnosis and causing 6.7 million annual deaths. Various risk factors, including genetics, metabolism, and the environment, influence the disease. While non-modifiable factors like ethnicity and family history play a role, addressing the modifiable risk factors such as lack of physical activity, obesity, and an unhealthy diet can potentially prevent T2DM. Dietary guidance is essential for improving patients’ lifespan and quality of life.

MedDiet emphasizes high consumption of extra-virgin olive oil, low-glycemic-index carbohydrates, and moderate fish, poultry, and dairy intake. Additionally, it limits the intake of red meat and alcohol. Evidence suggests that MedDiet can positively impact metabolic syndrome and T2DM, as demonstrated by lowered diabetes risk and improved glycemic profiles. The diet incorporates various aromatic herbs and spices, such as black cumin, clove, parsley, saffron, thyme, ginger, black pepper, rosemary, turmeric, basil, oregano, and cinnamon, known for potential health benefits, including antitumor, antioxidative, anti-inflammatory, and cholesterol-lowering properties. Therefore, researchers in the present study aimed to examine the effect of all these aromatic spices and herbs on the glycemic profiles of T2DM subjects.

About the study

For the present systematic review and meta-analysis, databases including Web of Science, PubMed, and Scopus to identify peer-reviewed articles and interventional studies. Case studies, commentaries, letters, conference papers, narrative reviews, and studies not conducted in humans or those involving children were excluded. The systematic review included 77 studies, while the meta-analysis included 45 studies (3050 participants).

The studies involved varying dosages of the spices and herbs and assessed their effect on glycemic profiles. The primary outcomes included fasting glucose, insulin, and HbA1c alterations, while secondary outcomes included variations in body weight and body mass index (BMI). Statistical analysis involved the determination of changes in means and standard deviation and the use of Cochrane Q and Higgins I² tests. The risk of publication bias was assessed using Egger plots. The quality of the included trials was assessed using the methodology described by Kmet et al.

Results and discussion

Cinnamon supplementation significantly reduced fasting glucose in six out of eleven studies. The meta-analysis indicated a reduction of 18.67 mg/dL compared to placebo, but the difference was not statistically significant in considering predictive value. Curcumin supplementation in seven studies showed a significant reduction in fasting glucose (p < 0.001) compared to placebo, with a significant difference including predictive value. Ginger supplementation in ten studies demonstrated a reduction in fasting glucose (17.12 mg/dL, p = 0.0004) compared to placebo, with no significant difference, including predictive value. Black cumin supplementation in eight studies resulted in a significant reduction in fasting glucose (p = 0.0001) compared to placebo, with no significant difference in considering predictive value. Using saffron supplementation resulted in substantially lowering glucose, an effect more pronounced when combined with physical activity. Overall, black cumin demonstrated the most substantial reduction in fasting glucose, followed by cinnamon and ginger.

Further, only ginger and black cumin exhibited a significant improvement in HbA1c, and cinnamon and ginger significantly decreased insulin levels. Among the analyzed aromatic herbs and spices in the MedDiet, ginger stood out as the sole contributor to significant decreases in all three examined outcomes: HbA1c, fasting glucose, and insulin level.

The quality of studies selected for the review (mean score 0.54) was lower than the quality of studies selected for the meta-analysis (mean score 0.68). Despite the large scale of the study, the findings are limited by the lack of consideration of body weight and lifestyle changes affecting fasting glucose levels, alongside challenges posed by varying study quality, inadequate statistical analyses, and the absence of standardized herb dosage information.

Conclusion

In conclusion, the present study could identify the potential therapeutic benefits of various aromatic herbs and spices in MedDiet for diabetes management. Further research is needed to determine optimal dosages and assess the impact of active components of the herbs and spices, facilitating their application in targeted interventions for glycemic control in T2DM patients.
Journal reference:

Effect of Aromatic Herbs and Spices Present in the Mediterranean Diet on the Glycemic Profile in Type 2 Diabetes Subjects: A Systematic Review and Meta-Analysis. Garza MC et al., Nutrients, 16(6):756 (2024), DOI: 10.3390/nu16060756, https://www.mdpi.com/2072-6643/16/6/756
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March 11, 2024
Mediterranean diet and exercise reshape gut microbiome, aiding weight loss
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In a recent study published in The American Journal of Clinical Nutrition, researchers investigate the health benefits of the Mediterranean diet (MedDiet) and physical activity interventions on overweight and obese participants by measuring changes in fecal metabolomic- and gut microbiota.

Study: Effect of 1-year lifestyle intervention with energy-reduced Mediterranean diet and physical activity promotion on the gut metabolome and microbiota: A randomized clinical trial. Image Credit: Valentyn Volkov / Shutterstock.com

Health benefits of the MedDiet

Characterized by a high intake of healthy vegetables, legumes, fruits, whole cereals, and nuts, moderate intake of seafood, low intake of dairy products and processed meats, as well as olive oil comprising the primary fat source, the traditional MedDiet has been growing in global popularity.

Previous studies have investigated the health benefits of the MedDiet, which include significant cardiovascular disease (CVD), obesity, neurological, and all-cause mortality risk reductions as compared to suboptimal dietary patterns like the Western diet.

The high concentrations of dietary fiber and anti-inflammatory nutraceuticals in the MedDiet have also been associated with promoting and persisting beneficial gut microbiota. To date, the metabolomic consequences of these associations remain unknown.

Exploring the blood metabolome provides important insights into how gut microbiota-derived metabolites correlate with cardiometabolic diseases. Through the use of plasma metabolomics and 16S sequencing, researchers can elucidate how diet, circulating metabolites, and gut microbiota impact cardiovascular health.

Understanding the influence of dietary interventions on both gut microbial composition and metabolomic profiles can support clinical recommendations to follow the MedDiet and other healthy diets, particularly in high-risk patients. Furthermore, these data can provide foundational insights for future studies investigating the indirect effects of diet on other non-cardiovascular somatic systems.

About the study

In the present study, researchers used data from the PREvención con DIeta MEDiterránea (PREDIMED)-Plus randomized trial to investigate the effects of one year of intensive lifestyle intervention on fecal metabolites, gut microbiota, and cardiovascular risk factors, particularly in overweight and obese patients. The study comprised 400 individuals between the ages of 55 and 75 years from Alicante, Barcelona, Reus, and Valencia who were randomly divided between the intervention group (IG) and control group (CG).

Data collection included dietary and lifestyle information obtained through the er-MedDiet questionnaire, a 17-item derivation of the 14-item Mediterranean Diet Adherence Screener (MEDAS) questionnaire. Blood and stool samples were also collected during baseline assessments and routine follow-up. Anthropometric measurements and demographic data were further obtained from medical and government records.

The researchers encouraged all study participants to increase their usual physical activity levels to include at least 45 minutes daily of brisk walking or an equivalent activity. All study participants were also encouraged to perform specific exercises that increase their balance, strength, and flexibility to ultimately complete 150 minutes or more of moderate-to-vigorous physical activity each week.

Changes in physical activity levels were quantified using questionnaires that assigned the metabolic equivalent of tasks (MET) min/week metrics to physical activity status and MET h/day for sedentary behaviors. The study intervention included lifestyle recommendations for physical activity and diet and in-person behavioral support from a licensed dietitian for the IG group. In contrast, CG was treated ad libitum with a regular MedDiet, which was the only intervention.

Outcomes of interest were measured using liquid chromatography-tandem mass spectrometry (LC-MS) for metabolomics identification, characterization, and quantification and 16S amplicon sequencing for gut microbiome evaluations. Linear regression models and weighted gene co-expression network analysis (WGCNA) were used to identify between-group differences and metabolomic sub-networks, respectively.

Study findings

The present study highlights the combined health benefits of a dietitian-guided MedDiet alongside physical activity compared to an ad libitum MedDiet.

Overweight and obese participants in the IG cohort exhibited a mean weight reduction of 4.2 kg and 4.4 cm lower waist circumference than their CG counterparts. The body mass index (BMI) and total energy intake estimates of the IG group were 1.5 kg/m² and 113.9 kcal lower than controls, thus explaining the 0.1% observed reductions in glycated hemoglobin values as compared to controls.

Fecal metabolomic analysis revealed a total of 532 fecal metabolites, four of which were significantly different between IG and CG following one year. These four metabolites included 4,7,10,13,16-docosapentaenoic acid (DPA) and adrenic acid, both of which decreased following the intervention, as well as oleic acid and 3-methyl-adipic acid (3-MAA), both of which increased following intervention. While preliminary analyses suggested an additional 56 metabolites of interest, these were non-significant following false discovery rate (FDR) corrections.

Network analyses grouped the 532 identified metabolites into 16 subnetworks ranging in size from Grey60 to brown. The Black, Midnight Blue, Pink, and Salmon subnetworks significantly differed between IG and CG cohorts following one year of the study.

The Black subnetwork comprised ceramides and spingosines, whereas the Midnight blue subnetwork consists of purines. The Pink subnetwork metabolites included fatty acids and carnitines, whereas the Salmon network comprised bile acids.

Compared to the CG, the IG exhibited reduced levels of the Black, Midnight Blue, and Pink subnetworks. Comparatively, the IG exhibited increased levels of the Salmon subnetwork compared to the CG.

Gut microbial analysis determined that IG Shannon and Chao1 alpha diversity indices were significantly higher than CG indices by the end of the study, with the top two axes of the principal coordinate analysis (PCoA) explaining 36% of the observed differences.

The Eubacterium hallii group exhibited a significant reduction in population size in the IG compared to the CG. A reduced abundance of Dorea was also observed but to a lesser extent than in the Eubacterium hallii group.

Conclusions

The present lifestyle intervention-based clinical trial highlights the benefits of stringent dietary supervision and physical activity engagement for at-risk overweight and obese individuals, even when compared to equal-risk subjects consuming a similarly healthy diet. The energy-reduced MedDiet and physical activity intervention in the IG, when compared with an ad libitum MedDiet for the CG, significantly reduced weight metrics, including waist circumference and BMI.

Even with similar healthy dietary patterns, the high intensity of the dietary intervention and weight-loss intervention components, such as caloric restriction and physical activity, could have significant benefits on CVD risk factors, potentially through modulation of the fecal microbiota and metabolome. Public health policies and interventions can be tailored to individual microbiome profiles, allowing for more precise and effective strategies for preventing and managing cardiometabolic diseases.”
Journal reference:

García-Gavilán, J. F., Atzeni, A., Babio, N., et al. (2024). Effect of 1-year lifestyle intervention with energy-reduced Mediterranean diet and physical activity promotion on the gut metabolome and microbiota: A randomized clinical trial. The American Journal of Clinical Nutrition. doi:10.1016/j.ajcnut.2024.02.021
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March 5, 2024
Better cognition and academic performance are associated with Mediterranean diet adherence

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In a recent study published in Nutrients, researchers investigated the relationship between various Mediterranean-style eating patterns and cognitive and academic performance among adolescent residents of Chile.

Study: Adolescents with a Favorable Mediterranean-Style-Based Pattern Show Higher Cognitive and Academic Achievement: A Cluster Analysis—The Cogni-Action Project. Image Credit: YuliiaHolovchenko/Shutterstock.com

Background

The Mediterranean diet (MedDiet) is a healthy eating pattern associated with higher cognitive and academic success among teenagers in developing nations.

It consists of high extra-virgin olive oil, vegetable, fruit, grain, nut, and legume consumption, moderate fish, meat, and dairy product consumption, and low egg and sweet consumption. The MedDiet promotes reducing the intake of processed and sugary foods, alcohol, and smoking.

The Western diet (WD), which includes ultra-processed foods, refined carbohydrates, and sugar, has been associated with cognitive decline in youngsters. In contrast, the MedDiet increases well-being and increased cognitive function.

However, the association between MedDiet and academic and cognitive abilities in teenagers has not been thoroughly explored in Latina communities.

About the study

In the present study, researchers explored the association between different Mediterranean-style eating patterns and cognitive and academic ability in Chilean adolescents.

The study was part of the Cogni-Action Project, which ran from March 2017 to October 2019 and involved 1,296 Chilean adolescents (males and females in a 1:1 ratio) aged 10 to 14 years from private, public, and subsidized (government-funded) schools in Chile.

The researchers performed a cluster analysis to uncover dietary trends and mixed modeling to examine the associations of diet clusters with cognition and academics.

The researchers used the MedDiet Quality Index to measure MedDiet adherence in children and adolescents and the NeuroCognitive Performance Test (NCPT) to assess cognitive performance.

They used principal component analysis (PCA) to uncover four cognitive domains: cognitive flexibility (CF), working memory (WM), fluid reasoning (FR), and inhibitory control (IC).

They assessed CF basis Trail-making tests A and B and Digit coding symbol tasks. WM tasks included memory forward and memory reverse, and the IC and FR assessments included the Go/No-Go and problem-solving tasks, respectively.

The researchers assessed academic success across five school disciplines (English, Language, Science, History, and Mathematics), including the Academic-Programme for International Student Assessment (PISA) score calculated as the mean of Mathematics, Science, and Language scores.

The study consisted of two sessions of participant evaluation spread over eight days. The first session evaluated body weight, height, waist circumference, eating habits, sociodemographic information, and a cognitive battery. The second session evaluated physical fitness using three factors (sex, maturity, and global fitness score).

Results

The team identified the following diet patterns: Western diet (WD, 4.3%), low fruits and vegetables, high-sugar diet (LFV-HSD, 28%), low fruits and vegetables, low-sugar diet (LFV-LSD, 42%), and MedDiet (25%).

There was a remarkable difference among the dietary clusters, primarily related to ultra-processed food, sugar, vegetable, and fruit intake.

Individuals in the Mediterranean diet group scored better in all cognitive domains compared to the Western diet, LFV-LSD, and LFV-HSD groups. The Western diet group underperformed academically in all assessments compared to other groups.

The Mediterranean diet was unique, attaining positive differences among all subjects compared to the LFV-HSD and Western diet groups.

The WD group exhibited lower performance across all cognitive domains than the MedDiet group except for inhibitory control. The MedDiet group showed positive differences in total cognitive performance, cognitive flexibility, inhibitory control, and working memory compared to the LFV-LSD cluster. However, fluid reasoning was not significantly different.

The Western diet group individuals underperformed in academic analyses than those in other groups. The Mediterranean diet cluster showed a significant difference in school students compared to the LFV-HSD and WD groups.

The MedDiet group scored better across all academic subjects than their LFV-LSD group counterparts; however, the differences did not attain statistical significance.

Conclusions

The study findings showed that Mediterranean-style eating patterns and higher-quality food preferences are related to superior adolescent academic and cognitive outcomes.

The study highlighted four dietary patterns: Western diet, LFV-LSD, LFV-HSD, and MedDiet, determined by adolescent adherence to or lack of particular MedDiet components. These clusters had significant disparities in the intakes of fruits, vegetables, junk food items, sugar, and fish.

The study implies that implementing total and intermediate adherence to MedDiet patterns in non-Mediterranean teenagers might be a viable first step in nutrition and public health, with superior outcomes in brain health and academic attainment.

A complete Mediterranean-style diet was associated with better academics and cognitive status than the Western diet.

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February 27, 2024
Mediterranean diet linked to lower depression risk in older women

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The Mediterranean diet (MD) is a popular and medically accepted diet for weight management and health promotion; however, the potential mental health benefits associated with this diet remain unclear. A new study in the British Journal of Nutrition discusses the association between MD and depressive symptoms in a cohort of older men and women.

Study: Adherence to Mediterranean diet is inversely associated with depressive symptoms in older women: findings from the NutBrain Study. Image Credit: PeopleImages.com – Yuri A / Shutterstock.com

Depression and aging

Current estimates indicate that about 5% of the global population suffers from depression, with depression among the leading causes of disability throughout the world. Importantly, the prevalence of depression increases with age, with one-third of older people affected.

Women are at greater risk for depressive symptoms from adulthood onwards, with this risk further increasing after the age of 60 years. In Italy, 10% of people over 65 years of age report depressive symptoms, with up to 14% of women 85 years and older experiencing depression.

Biological, psychological, social, and environmental factors contribute to the development of depression; therefore, diet can be considered a modifiable risk factor for this condition. Previous research has shown that following the MD is related to a lower risk of depressive symptoms overall.

The current study examined the association between MD, due to its ideal nutritional and antioxidant profile, and depressive symptoms. More specifically, the researchers were interested in clarifying the existence of this association, and especially sex-related differences, in older people, with the added contribution of separating these associations by dietary components.

Data were obtained from a food frequency questionnaire intended to semi-quantitatively assess adherence to the MD in the form of the Mediterranean diet score (MDS) and a depression measurement scale. Study participants were part of the population-based community-dwelling Nutrition, Gut Microbiota, and Brain Aging (NutBrain) cohort, and the study was conducted from October 2019 to January 2023.

What did the study show?

A total of 325 men and 473 women were included in the study, 60% of whom were between 65 and 74 years of age. The mean age was 73 years, with about 66% of study participants married and living with others, whereas 50% were considered underprivileged.

About 20% of the study cohort suffered from depressive symptoms, with 8% of men and 28% of women reporting depressive symptoms. Men with and without depression differed only in the significantly greater number of medications used in those with depression.

Among women, unmarried women, those living alone, those prescribed more drugs, and those who considered themselves to be sicker were more likely to experience symptoms of depression, as were those who ate less fish, vegetables, and healthy fats relative to saturated fat. About 33% of men reported adherence to the MD compared to 25% of women.

Study participants with the top third of MDS scores were 55% less likely to report depressive symptoms. When stratified by sex, women with the top third of MDS scores were at a 60% reduced risk of depression.

High fish consumption was associated with a 44% reduced risk of depressive symptoms in men and women. When stratified by sex, women with high fish consumption were 56% less likely to experience depressive symptoms. With each additional gram of fish consumption, the likelihood of depression declined by 2% overall and in women but not men.

The type of fish associated with a reduced risk of depression when three or more servings were consumed each week included shellfish, sole, trout, sea bream, cod, hake, and sea bass. This reduction was 62% overall for fish and 4% for shellfish.

When stratified by sex, women were associated with a reduced risk of depression by 43% with two to three servings of these fish each week; however, this risk further declined by 70% with three or more servings each week as compared to those consuming two or fewer servings of fish. This association was not observed in men.

Women with a high ratio of monounsaturated fatty acids to saturated fatty acids (MUFA/SFA) in their diet were 42% less likely to report depressive symptoms. For both men and women, nut and fruit consumption was associated with a reduced risk of depressive symptoms by 82% and 42%, respectively.

With each one-point increase in MDS, the risk of depressive symptoms decreased by 16% overall and by 18% in women. When only men were considered, this reduction was not significant.

What are the implications?

Adherence to the highest tertile of the MD is inversely associated with depressive symptoms and, in particular, this is only evident in women.”

The negative association of the MD, particularly fresh fish and higher MUFA/SFA, with depression corroborates earlier research.

The association of fresh fish with a reduced risk of depressive symptoms could be due to reduced inflammation, regulation of hypothalamic and pituitary hormones, which regulates other endocrine functions, reduced oxidative stress, gut microbiota profile, as well as other metabolic and intracellular pathways related to mental health.

The differential effects in women may be due to a higher prevalence of vitamin D deficiency in women, which is associated with poor mental health, including depression and psychosis, as well as changes in brain cell membranes caused by the supply of omega-3 fatty acids abundant in the MD. However, further research is needed to confirm these hypotheses.

While these findings cannot be experimentally confirmed, and the inclusion of study subjects may show multiple biases, the study cohort was representative of the older community in each locality. Despite these limitations, the study findings emphasize the key role of a healthy diet in promoting mental health in older people. Thus, public health efforts towards this goal will likely be productive, even as further studies are conducted to understand the biological processes responsible for these benefits.

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February 25, 2024
Mediterranean diet linked to better semen quality, study finds

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In a recent systematic review published in the journal Frontiers in Nutrition, researchers from Spain investigated the effect of the Mediterranean diet on the quality of semen in men of reproductive age. They found that adherence to the Mediterranean diet could improve male reproductive health by positively influencing semen quality.

Study: Influence of the Mediterranean diet on seminal quality—a systematic review. Image Credit: leonori / Shutterstock

Background

Fertility research has surged as about 15% of the global population, comprising 70 million reproductive-age couples, suffer from infertility across geographies and income groups. The World Health Organization investigated infertility across 25 nations and found that male factors contributed to about half of the couples, challenging the older notion that infertility is solely a female concern. The major causes of male infertility are impaired spermatogenesis, idiopathic causes, endocrine disorders, and altered sperm motility. Clinically investigating the cause of male infertility warrants thorough history, physical examination, and semen analysis. Additionally, non-modifiable factors such as genetics and age, alongside modifiable factors such as diet and lifestyle, are also known to influence male fertility.

Popular for its potential health benefits, the Mediterranean diet demonstrates positive associations with male reproductive health, including improved semen quality attributed to its anti-inflammatory and antioxidant properties. Evidence suggests that optimal adherence to this diet may lower the risk of various chronic diseases and potentially enhance male fertility by addressing metabolic factors affecting sperm function. Therefore, researchers in the present study conducted a systematic review to understand the effect of the Mediterranean diet on the quality of semen in men of reproductive age.

About the study

Data for this review were gathered through electronic searches in PubMed, the Cochrane Library, Scopus, and Web of Science, as well as reference lists. Full-text articles were screened based on criteria evaluated independently by two authors. The quality of studies was assessed using appropriate tools such as the Crombie criteria, the Newcastle-Ottawa Scale, and the PEDro scale. Interrater reliability was evaluated using Cohen’s kappa statistic.

Inclusion criteria were open-access articles published in English or Spanish between 2012 and 2022, focusing on men aged 18 to 55. The exclusion criteria excluded unrelated articles, systematic reviews, meta-analyses, conference proceedings, and studies of specific medical conditions. A total of 10 studies met the inclusion criteria, including a total of 2,032 participants across various countries, primarily Spain. Study designs included cross-sectional, cohort, case-control, and randomized controlled trials. Data extraction focused on variables such as nutrition status, diet, and semen quality assessment techniques. After extraction, data were grouped based on assessment techniques and associations between semen quality and the Mediterranean diet.

The quality of included studies was evaluated using the Cochrane Collaboration Risk of Bias tool, evaluating domains such as randomization, intervention deviations, missing outcome data, outcome measurement, selection of reported results, and other biases, classifying each item as having a low, high, or unclear risk of bias.

Nutrition status was evaluated using weight, height, body mass index (BMI), and waist circumference, while adherence to the Mediterranean diet was assessed using validated food frequency questionnaires or specific scores. Semen quality was primarily assessed through sperm concentration, motility, morphology, volume, total antioxidant capacity, and hormone levels. Some studies also explored chromosome stability, DNA (short for deoxyribonucleic acid) fragmentation, global sperm DNA methylation, microRNA (short for micro ribonucleic acid) expression, and reactive oxygen species.

Results and discussion

Six out of 10 studies demonstrated a positive association between semen quality and following the Mediterranean diet, particularly in parameters like sperm concentration, motility, and total sperm count. In three of them, men with higher adherence levels showed significantly higher semen quality. However, two studies found no significant association between Mediterranean diet adherence and semen quality.

The present study is the first to comprehensively investigate the positive link between the Mediterranean diet and semen quality. However, the study is limited by its small sample size, observational design, and low generalizability, with evidence quality rated as very low to moderate using the GRADE (short for Grading of Recommendations, Assessment, Development, and Evaluation) system. Risk of bias assessment for randomized controlled trials indicated one trial with low risk and another with bias concerns related to intervention deviations and result evaluation. Further research with larger sample sizes and randomized controlled trials is warranted to confirm these findings.

Conclusion

In conclusion, healthy dietary habits, particularly adherence to the Mediterranean diet, are found to be associated with improved semen quality in men of reproductive age. This diet, rich in polyunsaturated fatty acids, antioxidants, and anti-inflammatory substances, may reduce oxidative stress and protect against its adverse effects on sperm. These findings highlight the importance of dietary counseling for couples planning a pregnancy or undergoing assisted reproductive technology. However, further research is necessary to explore the relationship between diet and semen quality, informing strategies for improved fertility and health outcomes.

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February 20, 2024
Prenatal Mediterranean diet reduces offspring obesity

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In a recent study published in Nutrients, researchers determined the relationship between maternal Mediterranean diet (MedDiet) adherence during gestation and overweight or obese offspring risk at four years.

Study: Close Adherence to a Mediterranean Diet during Pregnancy Decreases Childhood Overweight/Obesity: A Prospective Study. Image Credit: Marian Weyo/Shutterstock.com

Background

The childhood obesity epidemic is a global health concern affecting millions of children under five, causing psychological comorbidities, low self-esteem, behavioral and emotional disorders, and long-term cardiovascular morbidity and cancer.

In addition, the World Health Organization’s (WHO) report emphasizes the importance of antenatal nutritional balance in preventing childhood obesity.

Close maternal adherence to a Mediterranean-style diet during gestation could be a promising strategy for determining potential obesity risks in childhood. Greater adherence to the diet has multiple health benefits for both mother and child.

However, studies examining the impact of prenatal diet on offspring obesity are scarce and yield varied results, warranting further research.

About the study

In the present study, researchers investigated whether maternal MedDiet adherence was associated with offspring obesity at four years and evaluated the impact of maternal factors on the association.

The team included 272 mother-child dyads from the Ensayo CLInico Para Suplementar con Hierro a EmbarazadaS (ECLIPSES) study for analysis.

The primary study outcome was offspring overweight or obese based on sex- and age-specific body mass index (BMI) z-scores above the 85th percentile using the WHO child growth standards.

The researchers obtained baseline maternal data from questionnaires during face-to-face interviews at recruitment, including medical history, age, educational level, socioeconomic status, physical activity, smoking status, and alcohol intake.

In addition to the gestational age at birth and delivery type, they obtained data on child-related variables, including sex, length, and weight at birth.

The team assessed prenatal diet using standardized 45-component food-frequency questionnaires (FFQs) at gestational weeks 12, 24, and 36 and calculated relative MedDiet (rMedDiet) scores. They measured offspring height and weight at four years.

They estimated the total daily calorie intake using the REGAL food table and determined household socioeconomic status using the Catalan classification of occupations (CCO-2011).

The researchers assessed physical exercise using the International Physical Activity Questionnaire (IPAQ) and categorized gestational weight gain (GWG) using the 2009 Institute of Medicine (IOM) recommendations.

They performed multivariate logistic regression modeling to determine the odds ratios (OR) for the association between prenatal diet and childhood obesity.

The ECLIPSES randomized clinical trial was conducted in Tarragona, Spain, from 2013 to 2017 to evaluate the efficacy of maternal iron supplementation in different dosages, adjusting for the initial hemoglobin levels during early gestation, on maternal iron status at the end of gestation.

Primary care midwives recruited 791 expecting women aged ≥18 years for the study during the initial prenatal visit (before week 12 of gestation).

Results

The mean maternal age was 32; 70% were aged ≥30, and 42% were obese or overweight, with body mass index values ≥25 kg m^-2.

Most (86%) mothers were from Spain, 44% received university-level education, 22% had high socioeconomic status, and 17% practiced smoking during pregnancy. Among the mothers, 29% showed low MedDiet adherence, whereas 23% were highly adherent.

The mean prenatal rMedDiet score was 9.80, and 26% of offspring were overweight or obese at four years, with a higher obesity prevalence among males (63%) than females (37%).

The team found significant anthropometric differences (height, weight, and body mass index) by sex. The mean body mass index and body weight of offspring at four years were 16 kg m^-2 and 18 kg, respectively.

Males had higher weight (19 versus 17 kg), BMI (16 versus 15.6), weight-for-age z scores (0.5 versus 0.1), and body mass index z-scores (0.7 versus 0.2) than females.

Overweight/obesity was less prevalent among offspring of mothers with university-level education, higher socioeconomic status, and higher gestational rMedDiet scores.

After adjusting for potential confounding variables, the team found higher prenatal MedDiet adherence related to a reduced risk of offspring being overweight or obese (OR for the highest versus lowest quartile, 0.3).

They obtained similar findings, stratifying by maternal age, early gestational BMI, educational attainment, smoking status, socioeconomic status, and GWG.

After confounder adjustment, the team found that each point increase in the prenatal MedDiet was associated with a 19% lower risk of children being overweight or obese at four years (OR, 0.8).

Smoking (OR, 2.5), pre-pregnancy overweight (OR, 2.5) or obesity (OR, 2.6), and excessive GWG (OR, 2.9) were considerably associated with offspring overweight or obese at four years.

The protective effects of MedDiet on offspring weight were higher among expecting women aged below 30 years with overweight or obese during initial gestation, those who did not smoke, and those with low socioeconomic status.

Conclusion

Overall, the study findings showed higher prenatal MedDiet adherence associated with lower reduced offspring overweight/obesity at four years, especially among university-educated mothers aged below 30 years from low socioeconomic backgrounds who did not smoke. Future studies could investigate whether the association persists across life stages.

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February 16, 2024
Mediterranean and vegetarian diets boost heart health by improving novel CVD markers

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In a recent study published in the journal Nutrition & Metabolism, researchers evaluated the impact of the lacto-ovo vegetarian diet (VD) and Mediterranean diet (MD) on apolipoprotein levels and cardiovascular disease (CVD) risk factors among low-moderate-risk individuals.

CVD is the leading cause of global mortality, necessitating the development of novel biomarkers for prevention, early diagnosis, and treatment. Apoproteins, which regulate lipoprotein metabolism, are considered a risk marker for CVD. The European Society of Cardiology (ESC) recommends ApoB as a CVD risk marker. ApoA-I, mainly found in high-density lipoprotein (HDL) lipids, play protective roles in reverse cholesterol transport. However, data on diet’s influence on apolipoproteins is limited.

Study: Effects of a dietary intervention with lacto-ovo-vegetarian and Mediterranean diets on apolipoproteins and inflammatory cytokines: results from the CARDIVEG study. Image Credit: Brian A Jackson / Shutterstock

About the study

In the present study, researchers assessed the influences of MD and VD diets on circulating apolipoproteins and their association with cardiovascular disease risk estimators, such as inflammatory cytokine levels and lipid profiles.

The study included 52 participants (39 women; mean age of 49 years) in the Cardiovascular Prevention with Vegetarian (CARDIVEG) diet randomized, crossover clinical trial. All individuals were at low-moderate CVD risk (<5.0% at ten years, using the ESC guidelines) and selected from the Clinical Nutrition Department of Careggi Hospital, Italy.

Eligibility individuals were overweight or obese with body mass index (BMI) ≥25 kg/m2 and ≥1.0 cardiovascular disease risk factors: low-density lipoprotein (LDL) beyond 115 mg dL^-1; triglyceride levels above 150 mg dL^-1; total cholesterol above 190 g/dL; and fasting blood glucose ranging from 110 to 125.0 mg dL^-1. The researchers excluded individuals with unstable medical conditions, medication prescriptions, expecting or breastfeeding women, and those who consumed poultry, fish, meat, or meat products or participated in weight loss programs in the previous six months.

The participants followed the MD (27 individuals) and VD (25 individuals) diets for three months. Both diets comprised 50% to 55% carbohydrates, 15% to 20% proteins, and 25% to 30% total fats (≤7.0% of saturated fat, less than 300 milligrams of cholesterol). The team provided the participants with one-week menu plans, different recipes, and precise data on foods to consume and avoid.

The primary outcomes were changes in body weight, fat mass, and BMI, and the secondary outcomes included changes in circulating CVD risk markers and apolipoprotein levels. The team obtained medical history, demographics, comorbidities, risk factors, lifestyle, and dietary data at study initiation. They collected blood samples with body composition and BMI data before and after the interventions.

The team used the Medi-Lite and National Health and Nutrition Examination Survey (NHANES) questionnaires to assess adherence to MD and VD diets, respectively. They conducted a primary analysis using general linear modeling, evaluating differences in apolipoprotein levels by sex, age, and CVD risk factors. They used linear regressions to examine the association between these changes and lipid profiles, inflammatory profiles, and dietary components.

Results

MD and VD improved lipid profiles and anthropometric variables, reducing total energy, fats, and cholesterol and increasing total carbohydrates. VD lowered protein and increased dietary fiber, while MD decreased body weight, fat mass, and BMI. VD also reduces fat-free body mass. VD reduced LDL by 5.0%, while MD reduced serum triglycerides by 9.0%. Both diets lowered inflammatory parameters, with MD significantly decreasing interleukin-10 by 37% and interleukin-17 by 49%.

Both diets reduced inflammatory parameters, with significantly higher (24%) ApoC-I levels after VD. Both diets increased ApoA-I (2.7% by VD and 6.1% by MD), ApoC-I (24% by VD and 11% by MD), and ApoD (6.5% by VD and 6.2% by MD) levels. However, ApoB/ApoA-I ratios reduced by 1.9% and 7.4% after VD and MD, respectively. Conversely, the team observed opposite trends for ApoB (+0.7% by VD and −1.6% by MD), ApoC-III (−5.6% by VD and +1.8% by MD), and ApoE (+14% by VD and −1.6% by MD).

The team found negative correlations between apolipoprotein C-III and carbohydrates after MD and between ApoD levels and saturated fats after VD. In contrast, they found positive correlations between HDL and ApoD after VD and between serum triglycerides, ApoCI, and ApoD after MD. IL-17 positively correlated with ApoB and ApoC-III after VD. However, they found significant negative correlations between ApoC-III and carbohydrate percentage after MD and between ApoD and saturated fat percentage after VD. Serum triglycerides showed positive correlations with ApoC-I and ApoD levels after MD.

HDL changes positively correlated with ApoD levels after VD. Linear regressions confirmed the results, adjusted for potential confounders such as weight change and the treatment order. The subgroup analyses showed that both diets positively influenced circulating apolipoproteins, especially in women aged ≥50 years with less than three cardiovascular disease risk factors.

The study findings showed that VD and MD improve cardiovascular disease risk in low-moderate CVD-risk individuals by regulating lipid and inflammatory profiles. MD more positively affects apolipoprotein levels, especially in women, individuals aged >50 years, and those with one or two CVD risk factors. The study also found differences in associations between apolipoprotein levels and specific nutrients, with an unexpected inverse association between carbohydrate intake and ApoC-III after MD.

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February 14, 2024