Associations between diet-related diseases and impaired physiological mechanisms: a holistic approach based on meta-analyses to identify targets for preventive nutrition

The Intersection Between COVID-19, Cardiovascular Disease, and Diet: a Review

PURPOSE OF REVIEW

Cardiovascular disease (CVD) is one of the top comorbidities associated with COVID-19-both pre- and post-infection. This review examines the relationships between COVID-19 infection and cardiovascular health, with a specific focus on diet as an important modifiable risk factor.

RECENT FINDINGS

Pandemic era studies of individuals battling and recovering from COVID-19 infection suggest a strong link between metabolic diseases, such as CVD, and SARS-CoV-2 infection susceptibility and severity. Other studies also demonstrate how COVID-19 lockdown policies and quarantine recommendations led to drastic lifestyle changes associated with increased CVD risk, such as reduced physical activity and lower diet quality. At the same time, new research is emerging that plant-based diets, which have previously been associated with lower CVD risk, may lower COVID-19 infection rates and severity of symptoms. Diet, COVID-19, and CVD intersect through complex biological mechanisms and related behavioral factors evidenced by clinical trials and epidemiological studies. Diet may be a critical tool for modifying risk of communicable and non-communicable conditions in the post-pandemic world.

Diet self-management: A qualitative study of college students' experiences and perspectives

Background

Overweight and obesity among college students have become an emergent public health concern, which may be effectively prevented by diet self-management (DSM). The purpose of this explorative study was to explore college students' experiences and perspectives on diet self-management (DSM), as well as its influencing factors.

Method

Thirty-three college students were recruited from different universities in China. A qualitative method was used to conduct semi-structured interviews with audio recording to explore their DSM experience and factors that influence DSM. Data were analyzed using thematic analysis to develop themes related to DSM.

Result

In the perception of what "good DSM" means, three themes and ten subthemes were identified: characteristics of good DSM (including 5 subthemes: regularity, balanced diet, no picky eating, good eating habits, and scientificity), method of good DSM (including three subthemes: self-control, adjusting, and making plans), and content of good DSM (including two subthemes: nutrition management and safety management). The influencing factors of DSM can be categorized into four levels of themes and 34 subthemes: individual, family, school, and social levels.

Conclusion

The results of this qualitative research highlighted the complexity and multi-dimension of DSM and its influencing factors. Our findings may help to inform diverse and needs-based intervention approaches to improve DSM and promote healthy diet among college students so as to prevent overweight and obesity.

A Sustainable and Global Health Perspective of the Dietary Pattern of French Population during the 1998–2015 Period from INCA Surveys

In France, the evolution of dietary pattern relative to sustainability and global health remains insufficiently studied. The objective of this study was to assess dietary changes during 1998–2015 through three generic metrics potentially related to sustainability. Food consumption data were collected from three French National Individual Study of Food Consumption surveys (INCA) for children (0–17 years) and adults (18–79 years) representative of the French population. The consumed foods were converted into plant (metric 1) and non-ultra-processed (UPF, metric 2) calories, and analyzed in meeting dietary recommended intakes (metric 3). French children and adults consumed high levels of animal and UPF calories, and nutrient deficiencies were observed in adults from the 2015 survey, e.g., fiber, EPA, DHA, magnesium, retinol, and vitamin C. In children, UPF daily calories increased from 42.8 to 45.5% and decreased in adults from 39.2 to 35.0%. In children and adults, diet revegetation was observed. While the level of physical activity decreased, overweight, obesity and type 2 diabetes prevalence increased in French adults. The French dietary pattern is not sustainable for global health unless public health policy is reinforced, with at least a twofold decrease in animal and UPF calories and improved food diversity.

Is milk and dairy intake a preventive factor for elderly cognition (dementia and Alzheimer's)? A quality review of cohort surveys

Milk and dairy (M&D) is a longstanding human food with widespread use. Many studies showed the preventive capacity of M&D in several human health disorders, but its utility in others is under discussion. Aging has been associated to elderly cognitive decline including dementia-Alzheimer syndrome (Dem-AD). The absence of a therapy to impede or postpone Dem-AD determines the need for its prevention, including nutritional factors. To evaluate the preventive capacity of M&D consumption in elderly Dem-AD we performed a systematic review in the main biomedical databases and information resources, but we present this study as a narrative review to discuss better the complexity of this subject. The elderly Dem-AD has a long pre-symptomatic period and the M&D intake has a widespread use. These determinants and the quality flaws of published studies impeach us to answer whether M&D consumption is preventive for Dem-AD. Moreover, two long Japanese cohorts suggest that M&D intake could prevent Dem-AD. Prospective cohorts beginning in midlife (or early life) could answer this question in the future.

How to protect both health and food system sustainability? A holistic 'global health'-based approach via the 3V rule proposal

OBJECTIVE

To define a generic diet to protect human health and food system sustainability based on three dimensions: animal:plant ratio, degree of food processing and food diversity.

DESIGN/SETTING

The percentages of maximum animal and ultra-processed energy content were evaluated from scientific papers (Web of Science database) and reports from international scientific institutions. Then, a weekly French standard diet, including these percentages and food diversity (≥42 different foods), was designed to calculate adequacy to nutritional needs.

RESULTS

Based on traditional and scientifically based healthy diets, and on foresight scenarios for sustainable diets at horizon 2050, a median daily animal energy content intake of 15 % was found to be protective towards both human health and environment. Based on epidemiological studies associating ultra-processed energy consumption with increased overweight/obesity risk, a precautionary threshold of approximately 15 % ultra-processed energy content was observed. The French diet allows addressing all nutritional needs and other nutritional indicators such as maximum salt and simple sugar consumption, α-linolenic acid:linoleic acid ratio and essential amino acids. This diet was named the '3V rule' for Végétal (plant), Vrai (real) and Varié (varied, if possible organic, local and seasonal). This generic diet can be adapted according to regional traditions and environmental characteristics. Excluding only one dimension of it would threaten both health and food system sustainability.

CONCLUSIONS

Tending towards a 3V-based diet, while respecting local constraints, should allow preserving human health, environment (greenhouse gas emissions, pollution, deforestation, etc.), small farmers, animal welfare and biodiversity, culinary traditions and socioeconomics (including an alleviation of public health cost).

The holistico-reductionist Siga classification according to the degree of food processing: an evaluation of ultra-processed foods in French supermarkets

The Siga classification of foods according to degree of processing showed that two-thirds of 24 932 packaged foods collected in French supermarkets are ultra-processed at various degrees.

Challenges of the heterogeneous nutrition response: interpreting the group mean

Extensive research demonstrates unequivocally that nutrition plays a fundamental role in maintaining health and preventing disease. In parallel nutrition research provides evidence that the risks and benefits of diet and lifestyle choices do not affect people equally, as people are inherently variable in their responses to nutrition and associated interventions to maintain health and prevent disease. To simplify the inherent complexity of human subjects and their nutrition, with the aim of managing expectations for dietary guidance required to ensure healthy populations and individuals, nutrition researchers often seek to group individuals based on commonly used criteria. This strategy relies on demonstrating meaningful conclusions based on comparison of group mean responses of assigned groups. Such studies are often confounded by the heterogeneous nutrition response. Commonly used criteria applied in grouping study populations and individuals to identify mechanisms and determinants of responses to nutrition often contribute to the problem of interpreting the results of group comparisons. Challenges of interpreting the group mean using diverse populations will be discussed with respect to studies in human subjects, in vivo and in vitro model systems. Future advances in nutrition research to tackle inter-individual variation require a coordinated approach from funders, learned societies, nutrition scientists, publishers and reviewers of the scientific literature. This will be essential to develop and implement improved study design, data recording, analysis and reporting to facilitate more insightful interpretation of the group mean with respect to population diversity and the heterogeneous nutrition response.

The Mediating Role of Overweight and Obesity in the Prospective Association between Overall Dietary Quality and Healthy Aging

BACKGROUND

Our objective was to quantify to what extent the association between adherence to the French nutritional recommendations at midlife, measured by the Programme National Nutrition Santé-Guideline Score (PNNS-GS), and healthy aging (HA) is mediated by body mass index (BMI) status.

METHODS

We analyzed data from 2249 participants of the French 'Supplementation with Vitamins and Mineral Antioxidants' (SU.VI.MAX-'SUpplémentation en VItamines et Minéraux AntioXydants') cohort. At baseline (1994⁻1995), data on BMI status (<25 vs. ≥25 and <30 vs. ≥30) and diet were collected. At follow-up (2007⁻2009), HA status (yes/no) was evaluated via a multidimensional concept focusing on chronic disease incidence, physical and cognitive functioning, mental and social health, pain, and perceived health. Relative risks (RR) were estimated by extensively adjusted robust-error-variance Poisson regression, and counterfactual-based mediation analysis was performed.

RESULTS

Our HA criteria were met by 39% of participants. We identified a positive direct relation of a greater adherence to the French nutritional recommendations, with the probability of HA (RR_Quartile ₄ _vsquartile ₁ = 1.31 (95% confidence interval (CI) = 1.13, 1.53)), and an indirect relation mediated by BMI status (1.01 (95% CI: 1.01, 1.02)), accounting for 5% of the total relation.

CONCLUSION

These results indicate that high dietary quality may contribute to the preservation of overall health during aging, partly via obesity prevention and partly via other mechanisms.

Evidence-based practice within nutrition: what are the barriers for improving the evidence and how can they be dealt with?

BACKGROUND

Evidence-based clinical research poses special barriers in the field of nutrition. The present review summarises the main barriers to research in the field of nutrition that are not common to all randomised clinical trials or trials on rare diseases and highlights opportunities for improvements.

METHODS

Systematic academic literature searches and internal European Clinical Research Infrastructure Network (ECRIN) communications during face-to-face meetings and telephone conferences from 2013 to 2017 within the context of the ECRIN Integrating Activity (ECRIN-IA) project.

RESULTS

Many nutrients occur in multiple forms that differ in biological activity, and several factors can alter their bioavailability which raises barriers to their assessment. These include specific difficulties with blinding procedures, with assessments of dietary intake, and with selecting appropriate outcomes as patient-centred outcomes may occur decennia into the future. The methodologies and regulations for drug trials are, however, applicable to nutrition trials.

CONCLUSIONS

Research on clinical nutrition should start by collecting clinical data systematically in databases and registries. Measurable patient-centred outcomes and appropriate study designs are needed. International cooperation and multistakeholder engagement are key for success.

The Healthy Core Metabolism: A New Paradigm for Primary Preventive Nutrition

Research in preventive nutrition aims at elucidating mechanism by which our diet helps us to remain in good health through optimal physiological functions. However, despite decades of accumulated data in human nutrition and regular subsequent nutritional recommendations, obesity and type 2 diabetes epidemics continue to progress worldwide each year leading to a regular decrease of the Healthy Life Years, notably in Western countries. Such a paradox may be explained by the Nutrition Transition, the extreme application of the reductionist paradigm in nutrition research, the lack of nutritional education and a too strong focus on curative nutrition in at risk/ill subjects. In this position paper, we hypothesized that researchers should focus more on healthy subjects, from birth until maturity. Rather than exploring what differentiates healthy and at risk/ill subjects, we propose to thoroughly study what characterizes a healthy state and its underlying metabolism. We define it as the Healthy Core Metabolism which remains stable whatever energy inputs (diets) and outputs (exercise), genetic background and external/internal stress, e.g., temporary illnesses. As a basis for Healthy Core Metabolism investigation, we observed that main physiological and ubiquitous functions of human organism, i.e., the neuro-vasculo-sarco-osteoporotic system, tend to follow a concave curve with common phases of growth, optimum, and decline. Finally, we hypothesized that true primary preventive nutrition should focus on the growth phase to reach the maximum capital of a given physiological function so that - whatever the further decline -, Healthy Life Years may approach or coincide with theoretical Life Expectancy.

Involvement of dietary saturated fats, from all sources or of dairy origin only, in insulin resistance and type 2 diabetes

Reducing the consumption of saturated fatty acids to a level as low as possible is a European public health recommendation to reduce the risk of cardiovascular disease. The association between dietary intake of saturated fatty acids and development and management of type 2 diabetes mellitus (T2DM), however, is a matter of debate. A literature search was performed to identify prospective studies and clinical trials in humans that explored the association between dietary intake of saturated fatty acids and risk of insulin resistance and T2DM. Furthermore, to assess whether specific foods, and not just the saturated fatty acid content of the food matrix, can have differential effects on human health, the relationship between consumption of full-fat dairy products, a main source of dietary saturated fatty acids, and risk of insulin resistance and T2DM was studied. There is no evidence that dietary saturated fatty acids from varied food sources affect the risk of insulin resistance or T2DM, nor is intake of full-fat dairy products associated with this risk. These findings strongly suggest that future studies on the effects of dietary saturated fatty acids should take into account the complexity of the food matrix. Furthermore, communication on saturated fats and their health effects should be prudent and well informed.

Associations between food and beverage groups and major diet-related chronic diseases: an exhaustive review of pooled/meta-analyses and systematic reviews

Associations between food and beverage groups and the risk of diet-related chronic disease (DRCD) have been the subject of intensive research in preventive nutrition. Pooled/meta-analyses and systematic reviews (PMASRs) aim to better characterize these associations. To date, however, there has been no attempt to synthesize all PMASRs that have assessed the relationship between food and beverage groups and DRCDs. The objectives of this review were to aggregate PMASRs to obtain an overview of the associations between food and beverage groups (n = 17) and DRCDs (n = 10) and to establish new directions for future research needs. The present review of 304 PMASRs published between 1950 and 2013 confirmed that plant food groups are more protective than animal food groups against DRCDs. Within plant food groups, grain products are more protective than fruits and vegetables. Among animal food groups, dairy/milk products have a neutral effect on the risk of DRCDs, while red/processed meats tend to increase the risk. Among beverages, tea was the most protective and soft drinks the least protective against DRCDs. For two of the DRCDs examined, sarcopenia and kidney disease, no PMASR was found. Overweight/obesity, type 2 diabetes, and various types of cardiovascular disease and cancer accounted for 289 of the PMASRs. There is a crucial need to further study the associations between food and beverage groups and mental health, skeletal health, digestive diseases, liver diseases, kidney diseases, obesity, and type 2 diabetes.

Toward a new philosophy of preventive nutrition: from a reductionist to a holistic paradigm to improve nutritional recommendations

The reductionist approach has been predominant to date in human nutrition research and has unraveled some of the fundamental mechanisms at the basis of food nutrients (e.g., those that involve deficiency diseases). In Western countries, along with progress in medicine and pharmacology, the reductionist approach helped to increase life expectancy. However, despite 40 y of research in nutrition, epidemics of obesity and diabetes are growing each year worldwide, both in developed and developing countries, leading to a decrease in healthy life years. Yet, interactions between nutrition-health relations cannot be modeled on the basis of a linear cause-effect relation between 1 food compound and 1 physiologic effect but rather from multicausal nonlinear relations. In other words, explaining the whole from the specific by a bottom-up reductionist approach has its limits. A top-down approach becomes necessary to investigate complex issues through a holistic view before addressing any specific question to explain the whole. However, it appears that both approaches are necessary and mutually reinforcing. In this review, Eastern and Western research perspectives are first presented, laying out bases for what could be the consequences of applying a reductionist versus holistic approach to research in nutrition vis-à-vis public health, environmental sustainability, breeding, biodiversity, food science and processing, and physiology for improving nutritional recommendations. Therefore, research that replaces reductionism with a more holistic approach will reveal global and efficient solutions to the problems encountered from the field to the plate. Preventive human nutrition can no longer be considered as "pharmacology" or foods as "drugs."