The impact of raw fermented milk products on perceived health and mood among Dutch adults

Sex and age differences in self-reported immune fitness

Studies have reported sex and age differences in self-rated health. On average, women rate their health as being poorer compared to men, and older individuals report poorer health than younger individuals. The current study evaluated sex and age differences for self-reported immune fitness, i.e. the capacity of the body to respond to health challenges (such as infections) by activating an appropriate immune response in order to promote health and prevent and resolve disease. Data from different survey studies (N = 8586) were combined for the current analyses. N = 8064 participants (93.3%) completed the single-item scale to assess momentary immune fitness (mean (Standard deviation, SD) age of 32.4 (16.7) years old, range: 18 to 103, 68.0% women) and N = 4263 participants (49.7%) completed the Immune Status Questionnaire (ISQ) to assess past year's immune fitness (mean (SD) age of 40.9 (17.1) years old, range: 18 to 103, 61.1% women). The analyses revealed that women rated their momentary and past year's immune fitness significantly lower than men (p < 0.001). A small but significant decline in momentary immune fitness when aging was found (r = -0.073, p < 0.001). In contrast, past year's immune fitness steadily improved with progressing age (r = 0.295, p < 0.001), and for each age group the difference from the 18-24 years old group was statistically significant (p < 0.001). When using age as covariate, the sex differences in immune fitness remained significant for both momentary immune fitness (p < 0.001) and past year's immune fitness (p < 0.001). In conclusion, women report a poorer momentary and past year's immune fitness than men. The sex effects in immune fitness are robust and seen across all age groups except the elderly. A relative stable momentary immune fitness was found across the age groups. However, past year's immune fitness (assessments with the ISQ) improved with age. This observation may be related to the fact that the studies comprised convenience samples. Therefore, the observed age effects should be interpreted with caution and require further investigation in nationally representative samples.

Fermented foods: Harnessing their potential to modulate the microbiota-gut-brain axis for mental health

Over the past two decades, whole food supplementation strategies have been leveraged to target mental health. In addition, there has been increasing attention on the ability of gut microbes, so called psychobiotics, to positively impact behaviour though the microbiota-gut-brain axis. Fermented foods offer themselves as a combined whole food microbiota modulating intervention. Indeed, they contain potentially beneficial microbes, microbial metabolites and other bioactives, which are being harnessed to target the microbiota-gut-brain axis for positive benefits. This review highlights the diverse nature of fermented foods in terms of the raw materials used and type of fermentation employed, and summarises their potential to shape composition of the gut microbiota, the gut to brain communication pathways including the immune system and, ultimately, modulate the microbiota-gut-brain axis. Throughout, we identify knowledge gaps and challenges faced in designing human studies for investigating the mental health-promoting potential of individual fermented foods or components thereof. Importantly, we also suggest solutions that can advance understanding of the therapeutic merit of fermented foods to modulate the microbiota-gut-brain axis.

Test-retest reliability of single-item assessments of immune fitness, mood, and quality of life

The use of single-item assessments is increasingly important and popular, as these enable quick real-time assessments in clinical practice or research. In this study we investigated the test-retest reliability of single-item assessments of mood ("stress", "anxiety", "depression", "fatigue", "loneliness", "being active", "optimism", and "happiness"), quality of life, and immune fitness in N = 108 participants. The analysis revealed high test-retest correlations between the single-item assessments (r = 0.67 to 0.90), moderate to excellent intraclass correlations (r = 0.672 to 0.889), and the Bland-Altman analysis revealed agreement between all test-retest assessments, except for depression. Taken together, it can be concluded that the single-item assessments of mood, quality and immune fitness have a good test-retest reliability. This strengthens the rationale for using these single item assessments.

Raw milk kefir: microbiota, bioactive peptides, and immune modulation

This study aims to characterize the microbiota and peptidomic composition of raw milk kefir, and to address the potential anti-allergic effects of raw milk kefir using validated research models for food allergy. Raw milk kefir was produced after incubation with a defined freeze-dried starter culture. Kefir was sampled during fermentation at seven time intervals. For comparison, kefir was also prepared from heat-treated milk. Peptide compositions were determined for the raw and heated milk, and kefir end products made from these milks. In a murine food allergy model, the two kefir end products were investigated for their allergy modulating effects. In both kefirs, we identified amplicon sequence variants identical to those in the starter culture, matching the bacteria Lactococcus lactis, Streptococcus thermophilus, Leuconostoc and the yeast Debaryomyces. In raw milk kefir, additional sequence variants of Lactococcus lactis and the yeasts Pichia and Galactomyces could be identified, which were absent in heated milk kefir. Analysis of peptide compositions in both kefirs indicated that the number and intensity of peptides drastically increased after fermentation. Heating of the milk negatively affected the diversity of the peptide composition in kefir. Only raw milk kefir suppressed the acute allergic skin response to the food allergen ovalbumin in sensitised mice. These effects coincided with differences in the T-cell compartment, with lower percentages of activated Th1 cells and IFNg production after treatment with kefir made from heated milk. The results of this study indicate specific properties of raw milk kefir that may contribute to its additional health benefits.

The Assessment of Immune Fitness

Immune fitness (i.e., adequate functioning of the immune system) is essential to maintain health, prevent and resolve disease, and improve quality of life. This article provides an overview of how to assess immune fitness. It discusses how a single-item rating scale can be used to assess immune fitness. The scale can be used in conjunction with a single "yes" or "no" question asking whether the individual is experiencing reduced immune fitness. Retrospective assessments can be complemented with the Immune Status Questionnaire (ISQ) to provide more insight into the type and frequency of experiencing specific immune-related complaints. Momentary assessments of immune fitness can be complemented with biomarker measurements in body fluids. As individuals may be unaware of systemic inflammation (e.g., biomarker concentrations outside the normal range), it remains critical to combine immune fitness assessments with biomarker measurements of immune functioning.

Pandemic Preparedness: Maintaining Adequate Immune Fitness by Attaining a Normal, Healthy Body Weight

In addition to developing effective medicines and vaccines, pandemic preparedness also comprises general health-related, behavioral, and psychological aspects related to being more resistant in the case of future pandemics. In the context of the 2019 coronavirus (COVID-19) pandemic, recent research revealed that reduced perceived immune fitness was the best predictor of reporting more frequent and more severe COVID-19 symptoms. Up until now (June 2022), during the COVID-19 pandemic, the majority of patients who have been hospitalized were characterized as being overweight. It is therefore essential to further evaluate the relationship between body mass index (BMI) and immune fitness. This was performed by analyzing pooled data from previously published studies, conducted among N = 8586 Dutch adults. It was hypothesized that attaining a normal, healthy body weight is associated with optimal perceived immune fitness. The analysis revealed that a deviation from normal weight (i.e., having a BMI outside the range of 18.5 to 24.9 kg/m²) was associated with significantly reduced perceived immune fitness, as assessed with the immune status questionnaire and a single item perceived immune fitness scale. The effects were significant for both underweight and overweight groups and most pronounced for the obese groups. The results suggest that attaining a normal, healthy body weight might significantly contribute to maintaining adequate perceived immune fitness. Therefore, attaining a normal body weight might be an essential component of pandemic preparedness and should be supported by creating awareness and promoting the importance of regular exercise and the consumption of healthy food.

Relationships between Dairy and Calcium Intake and Mental Health Measures of Higher Education Students in the United States: Outcomes from Moderation Analyses

Background: The prevalence of mental health concerns among university students in the United States (U.S.) continues to increase, while current treatments, including medication and counseling, present shortcomings. Higher dairy and calcium intakes are associated with protective effects on mental health; however, previous studies have focused on investigating singular relationships between dairy and calcium intakes and mental health measures. A more complex exploration of these relationships is warranted to better examine whether increasing dairy and calcium intakes could serve as an intervention to improve mental health. The present study sought to further characterize the relationships between dairy and calcium intake, perceived stress, and a variety of mental health measures using linear regression and moderation analyses. Methods: The present cross-sectional study involved students studying at three large U.S. universities, and data collection occurred from April to May 2020 when students were learning remotely due to the COVID-19 pandemic. An online survey comprising validated tools was distributed among students to assess dairy and calcium intake, perceived stress, anxiety, negative and positive moods, rumination, and resilience, sleep quality and duration, dietary risk, and physical activity. Results: A total of 1233 students completed the study. Higher dairy and calcium intake was coincident with lower perceived stress and higher positive mood scores, while higher calcium intake was also coincident with lower anxiety, rumination, and higher resilience scores. Additionally, as calcium intake increased, the relationship between perceived stress and anxiety and the relationship between perceived stress and negative mood weakened. Dairy intake did not have this effect. Conclusions: Based on the results, and considering that calcium is a shortfall nutrient, universities should consider initiating programs and public health campaigns to promote dairy and calcium intake among this population.

Immune Fitness and the Psychosocial and Health Consequences of the COVID-19 Pandemic Lockdown in The Netherlands: Methodology and Design of the CLOFIT Study

This article provides an overview of the design and methodology of the "Corona lockdown: how fit are you?" (CLOFIT) study, including the questionnaires and scales that were included in the online survey. The aim of the CLOFIT study was to investigate the psychosocial and health consequences of the coronavirus disease 2019 (COVID-19) pandemic in the Netherlands. The survey was conducted among the Dutch population to collect data on immune fitness and the psychological and health consequences of the 2019 coronavirus disease (COVID-19) pandemic lockdown in the Netherlands. The CLOFIT dataset contains measures from N = 1910 participants and is broadly representative of the Dutch general population. The dataset represents both sexes, a range of ages including the elderly, different education levels, and ethnic backgrounds. The cohort also includes people with a diverse health status and range of medication use.

Fermented milk containing Lactobacillus casei Zhang and Bifidobacterium animalis ssp. lactis V9 alleviated constipation symptoms through regulation of intestinal microbiota, inflammation, and metabolic pathways

Studies suggest that probiotics and fermented milk can improve defecation in constipated patients. However, the mechanism of fermented milk containing probiotics on constipation remains poorly understood. Volunteers with chronic constipation symptoms were recruited and given 200 g/d of fermented milk containing Lactobacillus casei Zhang and Bifidobacterium animalis ssp. lactis V9 (PFM) for 4 wk. Clinical symptoms, cytokines, metagenomics, and metabolomics were evaluated in constipated participants before and after PFM intervention. After PFM intervention, we observed significant improvement of constipation symptoms. In the serum samples, the anti-inflammatory cytokine IL-10 increased and the proinflammatory cytokine C-reactive protein and lipopolysaccharides decreased. Metagenomics results showed that the increase of B. animalis was correlated with an increase in defecation frequency. Fatty acid biosynthesis and bile acid biosynthesis in stool samples as well as carnitine shuttle, vitamin E metabolism, and ascorbate and aldarate metabolism were identified as significantly altered metabolic pathways. Acylcarnitine, located on the carnitine shuttle pathway, had a significantly positive correlation with defecation frequency. It was speculated that PFM may contribute to alleviating constipation symptoms through 3 potential mechanisms: fine-tuning gastrointestinal microbiota, fighting inflammation, and regulating metabolic pathways.

The Impact of Mood and Subjective Intoxication on Hangover Severity

The aim of this study was to investigate whether baseline mood and/or mood while drinking have an impact on alcohol hangover severity. A survey was held among N = 331 young adults (mean age = 23.6 years, range = 18-35 years). Demographics, alcohol consumption, subjective intoxication, and hangover severity were assessed for the past three days. In addition, mood (baseline, while drinking, and during hangover) was also assessed. N = 143 participants reported to be hungover on the day of assessment, N = 122 participants reported to have been hungover the previous day ('yesterday'), and N = 87 participants reported to have been hungover two days before the assessment ('2 days ago'). The analyses revealed that baseline mood and mood while drinking had no relevant effect on the amount of consumed alcohol and did not significantly contribute to hangover severity. However, hangover severity was associated with significantly increased negative affect, particularly with higher levels of subjective stress on the day of the hangover.

The food-gut axis: lactic acid bacteria and their link to food, the gut microbiome and human health

Lactic acid bacteria (LAB) are present in foods, the environment and the animal gut, although fermented foods (FFs) are recognized as the primary niche of LAB activity. Several LAB strains have been studied for their health-promoting properties and are employed as probiotics. FFs are recognized for their potential beneficial effects, which we review in this article. They are also an important source of LAB, which are ingested daily upon FF consumption. In this review, we describe the diversity of LAB and their occurrence in food as well as the gut microbiome. We discuss the opportunities to study LAB diversity and functional properties by considering the availability of both genomic and metagenomic data in public repositories, as well as the different latest computational tools for data analysis. In addition, we discuss the role of LAB as potential probiotics by reporting the prevalence of key genomic features in public genomes and by surveying the outcomes of LAB use in clinical trials involving human subjects. Finally, we highlight the need for further studies aimed at improving our knowledge of the link between LAB-fermented foods and the human gut from the perspective of health promotion.

Raw milk producers with high levels of hygiene and safety

There is world-wide increasing interest in the consumption of unprocessed, natural food commodities including fresh (unpasteurised) milk and milk products. Consumers are actively seeking out raw milk, partly due to health reasons, but also for taste, freshness, closeness to the producer and to support local agriculture. The need for high levels of hygiene and safety in farms producing raw milk for direct consumption has long been recognised and has led to federal and industry-initiated systems for safe raw milk production. Raw milk producers in North America and Europe have demonstrated that raw milk, intended for direct consumption, can be produced safe and hygienic. The aim of this paper is to describe practices that have been developed for safe raw milk production. The German Vorzugsmilch is a federally regulated programme for legal raw milk production that was established already in the 1930s to provide raw milk with high hygienic standards controlled for zoonotic diseases to consumers. The Raw Milk Institute is a non-profit organisation established in California that has developed a voluntary safe raw milk programme in North America. RAWMI has developed a risk analysis and management system for raw milk dairy farmers to assist farmers in making individually tailored solutions for various production systems. In British Colombia, Canada, small herd share farms have employed good manufacturing practices, a risk management approach and performed monthly samples for pathogens and indicator bacteria to demonstrate safety and consistency. The major components of the raw milk systems applied, and the results of regular milk microbial indicator bacteria are presented. For the German system, the results from standard monthly pathogen tests are compared to zoonotic pathogen tests from other milk sources. The overall results indicate that raw milk can be produced with a high level of hygiene and safety in various systems.

Development and Validation of the Immune Status Questionnaire (ISQ)

The self-assessment of perceived immune status is important, as this subjective observation leads individuals to decide whether or not to seek medical help or adapt their lifestyle. In addition, it can be used in clinical settings and research. The aim of this series of studies was to develop and validate a short questionnaire to assess perceived immune functioning. Five surveys were conducted among Dutch and International young healthy adults (18-30 years old), and two others among older age groups with various health complaints. For the first study, an existing immune functioning scale was modified and elaborated resulting in 23 immune-health-related items, of which the occurrence was rated on a 5-point Likert scale. A student sample was surveyed, and the results were used to shorten the 23-item listing into a 7-item scale with a predictive validity of 85%. Items include "sudden high fever", "diarrhea", "headache", "skin problems (e.g., acne and eczema)", "muscle and joint pain", "common cold" and "coughing". The scale is named Immune Status Questionnaire (ISQ), and it aims to assess perceived immune status over the preceding year. The second study revealed that the ISQ score correlated significantly with a 1-item perceived immune functioning (r = 0.383, p < 0.0001). In the third study, the final Likert scale descriptors were determined ("never", "sometimes", "regularly", "often" and "(almost) always)". The fourth study showed that the test-retest reliability of the ISQ is acceptable (r = 0.80). The fifth study demonstrated the association of ISQ scores with various neuropsychological and health correlates in an international sample, including perceived health and immune fitness, as well as levels of stress, fatigue, depression and anxiety. Study 6 demonstrated significant associations between ISQ scores and experiencing irritable bowel syndrome (IBS) symptoms in a sample of insomnia patients. Study 7 compared the effect of a dietary intervention in participants reporting "poor health" versus "normal health". It is shown that ISQ scores can differentiate between those with poor and normal health, and that an effective intervention is associated with a significant improvement in ISQ scores. Data from Study 7 were further used to determine an ISQ cut-off value for reduced immune functioning, and a direct comparison with 1-item perceived immune functioning scores enabled constructing the final scoring format of the ISQ. In conclusion, the ISQ has appropriate face, content, and construct validity and is a reliable, stable and valid method to assess the past 12 month's perceived immune status.

Effect of raw milk consumption on perceived health, mood and immune functioning among US adults with a poor and normal health: A retrospective questionnaire based study

INTRODUCTION

Raw milk consumption is controversially discussed, and people are looking for raw milk due to expected positive health impacts. The purpose of this consumer survey was to evaluate health conditions prior to and after consuming of raw milk (RM).

METHODS

An on-line survey was distributed in Spring 2018 among existing consumers of raw milk. One-Item health score, 1-item immunity score, immune status (ISQ), mood, bowel and skin conditions were rated retrospectively based on validated questionnaires. Data from 327 participants (age 54 years) were included, of which 156 (48%) were allocated to the poor health group after they reported being immune depressed or suffering from a chronic disease. Others were allocated to the normal health group. Milk consumption pattern before and after changing of the milk diet were recorded. All health outcomes were evaluated according a linear mixed model in SPSS.

RESULTS

Health, perceived immunity, bowel and mood scores increased post RM consumption with around 35% in the poor health group (P < 0.001), and around 9% in the normal health group (P < 0.001). Bowel and mood scores were overall lower in women than in men. Outcomes were independent of the origin of raw farm milk.

CONCLUSIONS

This consumer survey suggests that positive health and mood changes are associated with the consumption of raw milk. Effects were strongest in people with a self-reported poor health status as well as in women.