The effect of vegetarian diets on iron status in adults: A systematic review and meta-analysis

A cross-sectional survey exploring knowledge, beliefs and barriers to whole food plant-based diets amongst registered dietitians in the United Kingdom and Ireland

BACKGROUND

Plant-based diets (PBDs) have gained popularity in recent years due to their co-benefits for human and planetary health. Although clinical guidelines now recommend well-balanced PBDs, it remains unclear how dietitians in the United Kingdom (UK) and Republic of Ireland (ROI) view such diets and their implementation in practice. This study aimed to evaluate the perspectives of registered dietitians (RDs) on the role of a whole food plant-based diet (WFPBD) in clinical practice.

METHODS

A cross-sectional online survey was conducted amongst RDs in the UK and ROI between September and November 2023.

RESULTS

A total of 335 RDs participated in the survey. Most RDs (76%) agree that a well-planned WFPBD is suitable for all stages of life, with some (48%) expressing concerns over the risk of malnutrition and micronutrient deficiencies. Three-quarters of RDs (75%) incorrectly thought that plant protein is incomplete, necessitating protein combining. A WFPBD was on average ranked fourth out of 14 dietary strategies for managing some of the leading non-communicable diseases. Excluding dairy and eggs was the primary reason preventing RDs from personally adopting a WFPBD, whereas meal preparation and cost were the main barriers for their clients. The majority of RDs (79%) feel they did not receive sufficient education on WFPBDs, with 58% agreeing there are insufficient evidence-based resources available in their field. Only 33% feel supported when advocating for a WFPBD in their workplace.

CONCLUSIONS

Although many RDs view WFPBDs as viable and clinically relevant, significant barriers to their implementation exist, underscoring the need for enhanced education and support.

Developing and testing personalised nutrition feedback for more sustainable healthy diets: the MyPlanetDiet randomised controlled trial protocol

PURPOSE

Agriculture and food production contribute to climate change. There is mounting pressure to transition to diets with less environmental impact while maintaining nutritional adequacy. MyPlanetDiet aimed to reduce diet-related greenhouse gas emissions (GHGE) in a safe, nutritionally adequate, and acceptable manner. This paper describes the trial protocol, development, and testing of personalised nutrition feedback in the MyPlanetDiet randomised controlled trial (RCT).

METHODS

MyPlanetDiet was a 12-week RCT that provided standardised personalised nutrition feedback to participants based on new sustainable healthy eating guidelines (intervention) or existing healthy eating guidelines (control) using decision trees and corresponding feedback messages. To test the personalised nutrition feedback, we modelled a sample of 20 of the MyPlanetDiet participants baseline diets. Diets were modelled to adhere to control and intervention decision trees and feedback messages. Modelled nutrient intakes and environmental metrics were compared using repeated measure one-way analysis of covariance.

RESULTS

Intervention diets had significantly lower (p < 0.001) diet-related GHGE per 2500 kilocalories (kcal) (4.7 kg CO2-eq) relative to control (6.6 kg CO2-eq) and baseline (7.1 kg CO2-eq). Modelled control and intervention diets had higher mean daily intakes of macronutrients (carbohydrates, fibre, and protein) and micronutrients (calcium, iron, zinc, and iodine). Modelled control and intervention diets had lower percent energy from fat and saturated fat relative to baseline.

CONCLUSIONS

Adherence to the MyPlanetDiet personalised nutrition feedback would be expected to lead to better nutrient intakes and reduced diet-related GHGE. The MyPlanetDiet RCT will test the effectiveness and safety of personalised feedback for a more sustainable diet.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

Clinical trials registration number: NCT05253547, 23 February 2022.

Dietary patterns and association with Iron deficiency among children and adolescents aged 9-17 years in rural Guangzhou, China: a cross-sectional study

Background

Iron deficiency and iron deficiency anemia cause a huge disease burden worldwide. Diet is an important factor affecting the iron levels. This study aims to explore the dietary patterns of school-aged children in rural areas of Guangzhou and their association with iron deficiency.

Methods

Data on dietary surveys, lifestyle, demographic and laboratory tests were gathered from rural school-age children in Guangzhou. Factor analysis was applied to derive dietary patterns. Robust Poisson regression and subgroup analysis were used to analyze the association between dietary patterns and iron deficiency.

Results

A total of 2,530 children and adolescents aged 9-17 years were enrolled. The prevalence of iron deficiency was 13.36%. Four dietary patterns were identified including snack and fast-food pattern, fruit and vegetable pattern, cereal and tuber pattern and meat and offal pattern. Both children and adolescents in the Q4 group (the highest propensity) of snack and fast-food pattern and cereal and tuber pattern had a higher risk of iron deficiency than the Q1 group (the lowest propensity). Both children and adolescents in the Q4 group of meat and offal pattern and fruit and vegetable pattern had a lower risk of iron deficiency than the Q1 group. The results of stratified analysis showed the negative effect of snack and fast-food pattern and the protective benefits of meat and offal pattern are more obvious for boys, and the negative effect of cereal and tuber pattern were obvious for girls. The negative effect or protective benefits of the four dietary patterns were obvious for children aged 9-13.

Conclusion

Females, older children, and those with shorter sleep duration are at higher risk of iron deficiency. Snack and fast-food pattern and cereal and tuber pattern are risk factors for iron deficiency, and fruit and vegetable pattern and meat and offal pattern are protective factors for iron deficiency. The impact of diet on body iron levels is more obvious in boys and younger children. The findings of this study can provide evidence for formulating prevention and control measures on children and adolescents iron deficiency and iron deficiency anemia.

Health Benefits of Vegetarian Diets: An Insight into the Main Topics

Vegetarian diets are plant-based diets including all the edible foods from the Plant Kingdom, such as grains, legumes, vegetables, fruits, nuts, and seeds. Dairy and eggs can be added in small amounts in the lacto-ovo-vegetarian subtype, or not at all in the vegan subtype. The abundance of non-processed plant foods-typical of all well-planned diets, including vegetarian ones-can provide the body with numerous protective factors (fiber, phytocompounds), while limiting the intake of harmful nutrients like saturated fats, heme-iron, and cholesterol. The beneficial effects on health of this balance have been reported for many main chronic diseases, in both observational and intervention studies. The scientific literature indicates that vegetarians have a lower risk of certain types of cancer, overall cancer, overweight-obesity, type 2 diabetes, dyslipidemia, hypertension, and vascular diseases. Since the trend of following a vegetarian diet is increasing among citizens of developed countries, the knowledge in the field will benefit from further studies confirming the consistency of these findings and clarifying the effects of vegetarian diets on other controversial topics.

Nutrient Composition of Four Dietary Patterns in Italy: Results from an Online Survey (the INVITA Study)

Though Italy is a native land of Mediterranean diet, its adherence in the Italian population is low, witnessed by the high rates of overweight in its inhabitants. Vegetarian dietary patterns (i.e., lacto-ovo-vegetarian and vegan) are increasing in western countries, and also in Italy, where 9.5% of the population self-declared as vegetarian in 2023. Though the vegetarian diet has been associated with beneficial health effects, speculation on its alleged nutrient inadequacy exists. For this reason, we assessed the nutrient composition of the diet of 470 participants enrolled in an online survey (the INVITA study), who completed a weighted food questionnaire on three different days. Participants were divided into four dietary groups obtained according to their self-declared dietary intakes: 116 Meat Eaters (MEs), 49 Fish Eaters (FEs), 116 Lacto-Ovo-Vegetarians (LOVs), and 189 VegaNs (VNs). The mean intake of most of the main nutrients was similar among all groups and within the normal range expected for the Italian population, supporting the adequacy of diets within our Italian sample, especially the LOV and VN diet. Since the Mediterranean diet is a plant-based diet, some of its components still persist in the current Italian diet, representing a staple also for people adopting a vegetarian diet.

Investigation of bias due to selective inclusion of study effect estimates in meta-analyses of nutrition research

We aimed to explore, in a sample of systematic reviews (SRs) with meta-analyses of the association between food/diet and health-related outcomes, whether systematic reviewers selectively included study effect estimates in meta-analyses when multiple effect estimates were available. We randomly selected SRs of food/diet and health-related outcomes published between January 2018 and June 2019. We selected the first presented meta-analysis in each review (index meta-analysis), and extracted from study reports all study effect estimates that were eligible for inclusion in the meta-analysis. We calculated the Potential Bias Index (PBI) to quantify and test for evidence of selective inclusion. The PBI ranges from 0 to 1; values above or below 0.5 suggest selective inclusion of effect estimates more or less favourable to the intervention, respectively. We also compared the index meta-analytic estimate to the median of a randomly constructed distribution of meta-analytic estimates (i.e., the estimate expected when there is no selective inclusion). Thirty-nine SRs with 312 studies were included. The estimated PBI was 0.49 (95% CI 0.42-0.55), suggesting that the selection of study effect estimates from those reported was consistent with a process of random selection. In addition, the index meta-analytic effect estimates were similar, on average, to what we would expect to see in meta-analyses generated when there was no selective inclusion. Despite this, we recommend that systematic reviewers report the methods used to select effect estimates to include in meta-analyses, which can help readers understand the risk of selective inclusion bias in the SRs.

Comparison of nutritional profile between plant-based meat analogues and real meat: A review focusing on ingredients, nutrient contents, bioavailability, and health impacts

In order to fully understand the nutritional heterogeneity of plant-based meat analogues and real meat, this review summarized their similarities and differences in terms of ingredients, nutrient contents, bioavailability and health impacts. Plant-based meat analogues have some similarities to real meat. However, plant-based meat analogues are lower in protein, cholesterol and VB12 but higher in dietary fiber, carbohydrates, sugar, salt and various food additives than real meat. Moreover, some nutrients in plant-based meat analogues, such as protein and iron, are less bioavailable. There is insufficient evidence that plant-based meat analogues are healthier, which may be related to the specific attributes of these products such as formulation and degree of processing. As things stand, it is necessary to provide comprehensive nutrition information on plant-based meat products so that consumers can make informed choices based on their nutritional needs.

The effects of major dietary patterns on patients with type 2 diabetes: Protocol for a systematic review and network meta-analysis

BACKGROUND

Type 2 diabetes mellitus (T2DM) represents a significant worldwide health issue, experiencing an increasing incidence rate. Effective dietary strategies are vital for T2DM management, but the optimal dietary patterns remain debated due to inconsistent research outcomes and single-outcome reporting. Network Meta-Analysis (NMA) provides a powerful approach for integrating data from randomized controlled trials (RCTs), enabling a detailed evaluation of the impact of different dietary patterns. This document presents our strategy for a systematic review and network meta-analysis, aimed at assessing the influence of key dietary patterns on glycemic control, lipid profiles, and weight management in individuals with Type 2 Diabetes Mellitus (T2DM).

MATERIALS AND METHODS

Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P) and network meta-analyses guidelines, we conducted a comprehensive search of PubMed, EMBASE, and the Cochrane Library, without language or date restrictions. Our objective is to assess the efficacy of various dietary interventions in managing Type 2 Diabetes Mellitus (T2DM). We used standardized mean differences for pairwise comparisons and a Bayesian framework for ranking interventions via Surface Under the Cumulative Ranking Curve (SUCRA). Key analyses include heterogeneity, transitivity, and sensitivity assessments, along with quality and risk evaluations using the Cochrane Collaboration's tool and the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system.

ETHICS AND DISSEMINATION

This systematic review and network meta-analysis involve aggregate data from previous trials, obviating the need for additional ethical approval. The search strategy will be executed starting October 2023, with all searches completed by December 2023, to encompass the most current studies available. Findings will be shared through academic conferences and peer-reviewed journals focused on diabetes care and nutrition.

TRIAL REGISTRATION

PROSPERO registration number CRD42023465791.

Iron homeostasis in older adults: balancing nutritional requirements and health risks

Iron plays a crucial role in many physiological processes, including oxygen transport, bioenergetics, and immune function. Iron is assimilated from food and also recycled from senescent red blood cells. Iron exists in two dietary forms: heme (animal based) and non-heme (mostly plant based). The body uses iron for metabolic purposes, and stores the excess mainly in splenic and hepatic macrophages. Physiologically, iron excretion in humans is inefficient and not highly regulated, so regulation of intestinal absorption maintains iron homeostasis. Iron losses occur at a steady rate via turnover of the intestinal epithelium, blood loss, and exfoliation of dead skin cells, but overall iron homeostasis is tightly controlled at cellular and systemic levels. Aging can have a profound impact on iron homeostasis and induce a dyshomeostasis where iron deficiency or overload (sometimes both simultaneously) can occur, potentially leading to several disorders and pathologies. To maintain physiologically balanced iron levels, reduce risk of disease, and promote healthy aging, it is advisable for older adults to follow recommended daily intake guidelines and periodically assess iron levels. Clinicians can evaluate body iron status using different techniques but selecting an assessment method primarily depends on the condition being examined. This review provides a comprehensive overview of the forms, sources, and metabolism of dietary iron, associated disorders of iron dyshomeostasis, assessment of iron levels in older adults, and nutritional guidelines and strategies to maintain iron balance in older adults.

Animal board invited review: The contribution of red meat to adult nutrition and health beyond protein

Red meat has been a critical part of human diets for millennia, providing a source of high-quality protein, micronutrients and essential fatty acids. However, as societies evolved and industrialisation reshaped our food systems, there has been a noticeable shift in meat-eating trends driven by concerns about the environmental impact of meat production and its potential risk to health. Yet, despite falling out of favour with some dietary experts and influencers, meat has an important role in a healthy diet and most adults still consume it. This article explores the nutritional value of red meat, authorised nutrition and health claims, how red meat fits into diet, providing the example of the United Kingdom (UK), and the health benefits and risks associated with both eating and avoiding red meat. Benefits of red meat include nutrient density and bioavailability while risks include colorectal cancer at high intakes of processed meats, based on observational studies. Benefits of meat-free diets include a lower risk of chronic diseases, based on observational studies, while risks include nutrient inadequacy, higher bone fracture risk and low protein quality. Hence, a wholesale shift to plant-based diets may not benefit adults who are vulnerable to sub-optimal nutrient intakes, such as women of child-bearing age and the elderly. More evidence from randomised controlled trials is recommended to fully understand the benefits and risks of both meat-containing and meat-free diets.

Iron - a background article for the Nordic Nutrition Recommendations 2023

Iron absorption from foods is generally lower than that of most other nutrients and is highly variable depending on individual iron status and iron bioavailability in the meal. Several large population groups in the Nordic and Baltic countries are at risk of iron deficiency, including infants, young children, menstruating females, pregnant women as well as vegetarians. Iron deficiency leads to anemia, fatigue, and limited capacity for physical activity. Of particular concern is that iron deficiency anemia in young children is associated with impaired neurodevelopment. A comprehensive literature search has been performed and summarized. New factorial calculations have been performed considering iron losses, iron absorption and iron requirements in various population groups. Recent data on iron intakes and the prevalence of iron deficiency in the Nordic countries are presented. Average requirements and tentative recommended intakes are presented for 12 different population groups. Pregnant women and those with high menstrual blood losses should consume iron-rich food and undergo screening for iron deficiency. Infants should consume iron-rich complementary foods and cow's milk should be avoided as a drink before 12 months of age and limited to < 500 mL/day in toddlers. Vegetarians should consume a diet including wholegrains, legumes, seeds, and green vegetables together with iron absorption enhancers. There is no evidence that iron intake per se increases the risk of cancer or diabetes. Iron absorption from foods is generally lower than that of most other nutrients and can vary between <2 and 50% depending on individual iron status and iron bioavailability in the meal.

Variation observed in consensus judgments between pairs of reviewers when assessing the risk of bias due to missing evidence in a sample of published meta-analyses of nutrition research

OBJECTIVES

To evaluate the risk of bias due to missing evidence in a sample of published meta-analyses of nutrition research using the Risk Of Bias due to Missing Evidence (ROB-ME) tool and determine inter-rater agreement in assessments.

STUDY DESIGN AND SETTING

We assembled a random sample of 42 meta-analyses of nutrition research. Eight assessors were randomly assigned to one of four pairs. Each pair assessed 21 randomly assigned meta-analyses, and each meta-analysis was assessed by two pairs. We calculated raw percentage agreement and chance corrected agreement using Gwet's Agreement Coefficient (AC) in consensus judgments between pairs.

RESULTS

Across the eight signaling questions in the ROB-ME tool, raw percentage agreement ranged from 52% to 100%, and Gwet's AC ranged from 0.39 to 0.76. For the risk-of-bias judgment, the raw percentage agreement was 76% (95% confidence interval 60% to 92%) and Gwet's AC was 0.47 (95% confidence interval 0.14 to 0.80). In seven (17%) meta-analyses, either one or both pairs judged the risk of bias due to missing evidence as "low risk".

CONCLUSION

Our findings indicated substantial variation in assessments in consensus judgments between pairs for the signaling questions and overall risk-of-bias judgments. More tutorials and training are needed to help researchers apply the ROB-ME tool more consistently.

A microalgae docosahexaenoic acid supplement does not modify the influence of sex and diet on iron status in Spanish vegetarians or omnivores: A randomized placebo-controlled crossover study

OBJECTIVE

Plant-based diets are accepted as healthy, provided that are well-planned and include supplements. In this context, iron deficiency is a threat, and data from Spanish vegetarians are scarce. The aim of this study was to determine if a microalgae ω-3 supplement rich in docosahexaenoic acid (DHA) affected iron status in this population.

METHODS

Iron biomarkers and nutrient intake (72-h dietary records) were analyzed in 204 usual consumers of lacto-ovo vegetarian (LOV), vegan (VEG), or omnivorous (OMN) diets. A randomized double-blind, placebo-controlled crossover trial was performed in a subgroup (n = 98) to test if a microalgae DHA supplement (250 mg/d for 5 wk) changed iron status.

RESULTS

Iron intake was higher in vegetarians than omnivores (P= 0.002), fiber intake was highest in vegans followed by lacto-ovo vegetarians and omnivores, whereas calcium intake was lower in vegans than both lacto-ovo vegetarians and omnivores (all P < 0.001). Women, regardless of diet type, showed lower iron status than men. Erythrocytes, hemoglobin, hematocrit, and serum ferritin were lower in lacto-ovo vegetarians and vegans than omnivores. The prevalence of iron deficiency anemia was low (<10%), but iron depletion (ferritin <15 ng/mL) was higher in lacto-ovo vegetarians than omnivores (P = 0.003). Iron biomarkers were similar in lacto-ovo vegetarians and vegans. The DHA supplementation did not change iron status compared with placebo.

CONCLUSIONS

Spanish vegetarians had lower iron status than omnivores. Consumption of eggs and dairy products increased the risk for iron deficiency, but a microalgae DHA supplement had no effect. Dietary strategies to increase iron bioavailability in vegetarians, particularly in lacto-ovo vegetarians and women, are recommended.

The potential for the use of leghemoglobin and plant ferritin as sources of iron

Iron is an essential component for the body, but it is also a major cause for the development of many diseases such as cancer, cardiovascular diseases, and autoimmune diseases. It has been suggested that a diet rich in meat products, especially red meat and highly processed products, constitute a nutritional model that increases the risk of developing. In this context, it is indicated that people on an elimination diet (vegetarians and vegans) may be at risk of deficiencies in iron, because this micronutrient is found mainly in foods of animal origin and has lower bioavailability in plant foods. This article reviews the knowledge on the use of leghemoglobin and plant ferritin as sources of iron and discusses their potential for use in vegetarian and vegan diets.

Biology of Anemia: A Public Health Perspective

Our goal is to present recent progress in understanding the biological mechanisms underlying anemia from a public health perspective. We describe important advances in understanding common causes of anemia and their interactions, including iron deficiency (ID), lack of other micronutrients, infection, inflammation, and genetic conditions. ID develops if the iron circulating in the blood cannot provide the amounts required for red blood cell production and tissue needs. ID anemia develops as iron-limited red blood cell production fails to maintain the hemoglobin concentration above the threshold used to define anemia. Globally, absolute ID (absent or reduced body iron stores that do not meet the need for iron of an individual but may respond to iron supplementation) contributes to only a limited proportion of anemia. Functional ID (adequate or increased iron stores that cannot meet the need for iron because of the effects of infection or inflammation and does not respond to iron supplementation) is frequently responsible for anemia in low- and middle-income countries. Absolute and functional ID may coexist. We highlight continued improvement in understanding the roles of infections and inflammation in causing a large proportion of anemia. Deficiencies of nutrients other than iron are less common but important in some settings. The importance of genetic conditions as causes of anemia depends upon the specific inherited red blood cell abnormalities and their prevalence in the settings examined. From a public health perspective, each setting has a distinctive composition of components underlying the common causes of anemia. We emphasize the coincidence between regions with a high prevalence of anemia attributed to ID (both absolute and functional), those with endemic infections, and those with widespread genetic conditions affecting red blood cells, especially in sub-Saharan Africa and regions in Asia and Oceania.

Diet and odor hedonic ratings: comparative study between vegetarians, flexitarians, and omnivores

OBJECTIVES

Odor hedonic perception is well known to exhibit great variability and to depend on several parameters, i.e. stimulus, context, and subject characteristics. As hedonic perception (pleasant/unpleasant character) of food odors is considered one of the most prominent dimensions in eating behavior, the question of hedonic variability in this context arises. Thus, the aim of the present study was to compare odor hedonic ratings in three populations with regard to diet (i.e. omnivore, vegetarian, and flexitarian diets).

METHODS

Four categories of odors were compared: meat, vegetable, other food, and non-food odors.

RESULTS

The results showed that vegetarian and flexitarian individuals rated meat odors as more unpleasant than omnivores, while no significant difference was found for other categories of odors.

DISCUSSION

The question of whether the diet influences the hedonic perception or/and inversely is discussed, regarding several aspects of food consumption such as eating disorders, food education, … and could further serve to manage eating behaviors.

PRACTICAL APPLICATIONS

This study evidenced that vegetarians and flexitarians specifically rated meat odors as being more unpleasant than those of omnivores. Because of the growing number of vegetarians and flexitarians in the general population, it could be suggested to take into account the odor hedonic perception (especially regarding food odors) in studies related to diets. Besides, the present results could further serve research in several aspects of food consumption such as eating disorders (anorexia, bulimia … etc.) or food education as well as the management of eating behaviors, especially in an elderly population.

Moving towards more sustainable diets: Is there potential for a personalised approach in practice?

Discourse on the relationship between food production, healthy eating and sustainability has become increasingly prominent and controversial in recent years. Research groups often take one perspective when reporting on sustainable diets, and several often neglect considerations for the multiple aspects that make a diet truly sustainable, such as cultural acceptability, differences in nutritional requirements amongst the population and the efficiency of long-term dietary change. Plant-based diets are associated with lower greenhouse gas emissions (GHGEs) and have been linked with better health outcomes, including lower risk of diet-related chronic disease. However, foods associated with higher GHGE, such as lean red meat, fish and dairy, have beneficial nutritional profiles and contribute significantly to micronutrient intakes. Some research has shown that diets associated with lower GHGE can be less nutritionally adequate. Several countries now include sustainability recommendations in dietary guidelines but use vague language such as "increase" or "consume regularly" when referring to plant-based foods. General population-based nutrition advice has poor adherence and does not consider differences in nutritional needs. Although modelling studies show potential to significantly reduce environmental impact with dietary changes, personalising such dietary recommendations has not been studied. Adapting recommendations to the individual through reproducible methods of personalised nutrition has been shown to lead to more favourable and longer-lasting dietary changes compared to population-based nutrition advice. When considering sustainable healthy dietary guidelines, personalised feedback may increase the acceptability, effectiveness and nutritional adequacy of the diet. A personalised approach has the potential for delivering a new structure of more sustainable healthy food-based dietary guidelines. This review evaluates the potential to develop personalised sustainable healthy food-based dietary guidelines and discusses potential implications for policy and practice.

Vegan diet: nutritional components, implementation, and effects on adults' health

Vegan diet has emerged as a popular dietary choice for people worldwide in recent times, due to concerns such as health issues, animal rights and welfare, and the sustainability of the environment. The purpose of this literature review was to explain how a vegan diet may affect the health of adults and to point out beneficial components found in it as well as any difficulties associated with its implementation. Evidence supports that a vegan diet can reduce the risk of chronic diseases, such as type 2 diabetes, hypertension, and certain types of cancer. A well-planned vegan diet must include adequate calories and nutrients, as well as the necessary supplements, such as vitamin B12, vitamin D and EPA/DHA. Given the current growing interest in plant-based diets among the general population, it is crucial to understand both the barriers, risks, and benefits of the vegan diet among physicians, policy makers, and the general population.

Exploring Benefits and Barriers of Plant-Based Diets: Health, Environmental Impact, Food Accessibility and Acceptability

Unhealthy dietary patterns are directly linked to the current Global Syndemic consisting of non-communicable diseases, undernutrition and climate change. The dietary shift towards healthier and more sustainable plant-based diets is essential. However, plant-based diets have wide intra differences; varying from vegan diets that totally exclude meat and animal products to traditional ones such as the Mediterranean diet and the new Nordic diet. It is acknowledged that plant-based diets may contribute simultaneously to improving population health as well as to decreasing the environmental impact of food systems. Evidence from cohort and randomized-controlled trials suggests that plant-based dietary patterns have beneficial effects on bodyweight control, cardiovascular health and diabetes prevention and treatment. On the other hand, micronutrient requirements may not be met, if some plant-based diets are not well-planned. Additionally, studies showed that lower consumption of meat and animal products results in lower environmental impacts. Consequently, plant-based diets could be a key factor to increase diet sustainability. This narrative review addresses the advantages of adherence to plant-based diets on human and planetary health considering strains and barriers to achieve this dietary transition, including cultural acceptability and affordability factors. Finally, potential intervention and policy recommendations are proposed, focusing on the update of current national food-based dietary guidelines.

Plant-based diets: a fad or the future of medical nutrition therapy for children with chronic kidney disease?

Plant-based diets are growing in popularity worldwide due to the importance of reducing the population's ecological footprint as well as an emerging role in the prevention and treatment of chronic human diseases. In adults, plant-based diets have been shown to be beneficial for preventing and controlling conditions that are common in patients with chronic kidney disease (CKD), such as obesity, hypertension, type 2 diabetes, dyslipidemia, and metabolic acidosis. Emerging evidence suggests that the higher fiber content of plant-based diets may help to modulate production of uremic toxins through beneficial shifts in the gut microbiome. The effects of the plant-based diet on progression of CKD remain controversial, and there are no data to support this in children. However, knowledge that the bioavailability of potassium and phosphorus from plant-based foods is reduced has led to recent changes in international kidney-friendly diet recommendations for children with CKD. The new guidelines advise that high potassium fruits and vegetables should no longer be automatically excluded from the kidney-friendly diet. In fact, a plant-based diet can be safely implemented in children with CKD through building the diet around whole, high fiber foods, avoiding processed foods and using recommended cooking methods to control potassium. The health benefits of the plant-based diet compared to omnivorous diets in children with CKD need investigation.

Vegetarian diets and diets which restrict animal-source foods during childhood in high-income countries

Increasing numbers of populations in the West are restricting their intake of meat and other animal products for reasons relating to health or ethics; in many countries, these restrictions are already common for cultural, religious, or socio-economic reasons. By following their parent's diet, children are exposed in parallel. This narrative review aims at assessing current data regarding vegetarian diets in children from birth to 18 years of age, which include, by increasing degree of restriction, flexitarian, lacto-ovo-vegetarian, lacto-vegetarian, pescatarian, vegan and macrobiotic diets. The 202 references include 45 studies in children. The more restrictive the diet and the younger the child, the greater the risk of nutritional deficiency. Of particular concern are vitamin B12, iron, zinc, calcium, n-3 long-chain polyunsaturated fatty acids, and protein and energy intake, especially in pregnant and nursing women, infants and young children. Providing an adequate lacto-ovo-vegetarian diet is relatively easy, whereas the maintenance of more restrictive diets may be challenging. The benefits and risks of vegetarian diets in adults are relatively well documented, but data for children are scarce. Vegan and macrobiotic diets should be discouraged in pregnant and lactating mothers as well as in young children, who, otherwise, should pay careful attention to ensuring nutritional adequacy, blood testing and appropriate supplementation. The health consequences of a chosen diet should be discussed with parents and adolescents to ensure the best possible adherence to advice and prescriptions. There is a need for well conducted studies in children but also for better knowledge of nutrition in healthcare professionals.Abbreviations: ALA: α-linolenic acid; ARA: arachidonic acid; ASF: animal source foods; BMC: bone mineral content; BMD: bone mineral density; DHA: docosahexaenoic acid; DRV: dietary reference value; EPA: eicosapentaenoic acid; FLD: flexitarian diet; LA: linoleic acid; LC-PUFA: long-chain polyunsaturated fatty acids; LOVD: lacto-ovo-vegetarian diet; LVD: lacto-vegetarian diet; MAD: macrobiotic diet; OMD: omnivorous diet; PSF: plant-source foods; SFA: saturated fatty acids; VGD: vegetarian diets; VND: vegan diet.

Health aspects of vegan diets among children and adolescents: a systematic review and meta-analyses

Health effects of vegan diets among children and adolescents are a controversial public health topic. Thus, the aim of the present systematic review is to evaluate a broad range of health outcomes among vegan children and adolescents aged 0 to 18 years. 18 studies met the inclusion criteria (17 cross-sectional, 1 RCT). Meta-analyses showed lower protein, calcium, vitamin B2, saturated fatty acid, and cholesterol intakes, and lower ferritin, HDL and LDL levels as well as height in vegan compared to omnivorous children/adolescents. Higher intakes of carbohydrates, polyunsaturated fatty acids, fiber, folate, vitamins C and E, magnesium, iron, and potassium were observed in vegans. Blood levels of vitamin B12 were higher among vegan children due to supplement use. Single study results suggested further differences between vegan and non-vegan children, such as lower bone mineral content or urinary iodine among vegan children. Risk of Bias was rated as high or very high in 7 out of 18 studies. The certainty of evidence for the meta-analyses was low (n = 2) or very low (n = 46). Overall, the available evidence points to both risks and benefits associated with a vegan diet among children, although more and better designed studies are needed.

Toddlers may be getting enough iron in long day-care services after all

BACKGROUND

Previous research has suggested that toddlers are not provided with adequate dietary iron in long-day care (LDC) services. However, the iron bioavailability provided is unknown. The present study aimed to investigate the amount and bioavailability of iron provided to toddlers aged 2-3 years at LDC services.

METHODS

A cross-sectional audit was conducted using a 2-day weighed food record of 30 LDC services. Iron provision (not child intake) in LDC services across Perth, Australia was compared with the estimated average requirements (EAR) and LDC services provision guidelines (50% of EAR = 2 mg/day based on a 14% bioavailability factor). Bioavailability was estimated per mealtime using haem and non-haem iron, ascorbic acid, animal protein, calcium, soy, eggs and phytates using two pre-existing algorithms (by A. P. Rickard and colleagues and H. Hallberg and H. Hulten).

RESULTS

Median iron supplied (2.52 mg/day, interquartile range [IQR] = 2.43-3.17) was above the 50% of EAR of 2.0 mg/day (p < 0.001). Median bioavailable iron was 0.6 mg/day (IQR = 0.54-0.8) using the method of Rickard et al. and 0.51 mg/day (IQR = 0.43, 0.76 using that of Hallberg and Hulthen). The top three foods contributing to iron provision were bread, breakfast cereals and beef.

CONCLUSIONS

Our results suggest that LDC services in Perth are meeting the minimum recommendation of provision of 50% of the iron EAR, and also that toddlers are provided with sufficient bioavailable iron. Future strategies should focus on promoting food combinations to maintain the iron bioavailability in meals currently served at LDC services.

Factors Influencing the Hepcidin Response to Exercise: An Individual Participant Data Meta-analysis

BACKGROUND

Hepcidin, the master iron regulatory hormone, has been shown to peak 3-6 h postexercise, and is likely a major contributor to the prevalence of iron deficiency in athletes. Although multiple studies have investigated the hepcidin response to exercise, small sample sizes preclude the generalizability of current research findings.

OBJECTIVE

The aim of this individual participant data meta-analysis was to identify key factors influencing the hepcidin-exercise response.

METHODS

Following a systematic review of the literature, a one-stage meta-analysis with mixed-effects linear regression, using a stepwise approach to select the best-fit model, was employed.

RESULTS

We show that exercise is associated with a 1.5-2.5-fold increase in hepcidin concentrations, with pre-exercise hepcidin concentration accounting for ~ 44% of the variance in 3 h postexercise hepcidin concentration. Although collectively accounting for only a further ~ 3% of the variance, absolute 3 h postexercise hepcidin concentrations appear higher in males with lower cardiorespiratory fitness and higher pre-exercise ferritin levels. On the other hand, a greater magnitude of change between the pre- and 3 h postexercise hepcidin concentration was largely attributable to exercise duration (~ 44% variance) with a much smaller contribution from VO2max, pre-exercise ferritin, sex, and postexercise interleukin-6 (~ 6% combined). Although females tended to have a lower absolute 3 h postexercise hepcidin concentration [1.4 nmol·L-1, (95% CI [- 2.6, - 0.3]), p = 0.02] and 30% less change (95% CI [-54.4, - 5.1]), p = 0.02) than males, with different explanatory variables being significant between sexes, sample size discrepancies and individual study design biases preclude definitive conclusions.

CONCLUSION

Our analysis reveals the complex interplay of characteristics of both athlete and exercise session in the hepcidin response to exercise and highlights the need for further investigation into unaccounted-for mediating factors.

Major and trace mineral composition of milk from lactating women following vegan, vegetarian and omnivore diets

Approximately one-in-ten reproductive age adults in the USA follow a plant-based diet, yet there is limited information on the influence of vegan and vegetarian diets on the mineral composition of breast milk. This study explored the major and trace mineral composition in breast milk and associations with maternal diet patterns. We used a cross-sectional design to collect a single sample of breast milk from individuals following vegan (n 23), vegetarian (n 19) and omnivore (n 21) diet patterns. Plant-based diet (n 42) was defined as following either vegan or vegetarian diets. Sixteen minerals were assessed using inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectrometry. Data were evaluated using traditional statistical techniques and five different machine learning approaches. The distribution of Se (median; quartile 1 and 3) was significantly different between groups (vegetarians 21, 18-26 µg/l; vegans 19, 18-25 µg/l and omnivores 17, 14-20 µg/l; P = 0·007) using a Kruskal-Wallis test. Machine learning techniques also identified Se as a potential biomarker for differentiating breast milk by maternal diet pattern. Individuals following a plant-based diet generally had a lower BMI, higher breast milk Se and lower breast milk I and Fe concentrations compared with those following omnivore diets. This suggests that maternal dietary pattern (plant-based v. omnivore) may be helpful clinical information to consider when caring for the breast-feeding dyad, with the strongest evidence related to differences in Se concentration.

Health benefits of legume seeds

Pulses have been part of human nutrition for centuries. They are also used in folk medicine as products with multidirectional medicinal effects. They are annual plants representing the Fabaceae family. Their edible part is the fruit, i.e. the so-called pods. Whole pods or their parts can be eaten, depending on the species and fruit ripeness. Beans, peas, peanuts, chickpeas, lentils, broad beans and soybeans are edible legume species. Legume seeds are characterized by high nutritional value. Compared to seeds from other plants, they have high protein content ranging, on average, from 20% to 35%, depending on the type, growing conditions and maturity of the fruit. This review focuses on various health-promoting properties of legumes and presents their nutritional value and compounds exerting health-promoting effects. Many pulses have a low glycemic index, which is important for prevention and treatment of diabetes. In addition to their low glycemic index and high fiber content, pulses have α-amylase and α-glucosidase inhibitors, which reduce the absorption of glucose from the gastrointestinal tract. These compounds have antidiabetic and anti-inflammatory effects. Pulses have been shown to contain bioactive peptides with angiotensin-converting enzyme inhibitory properties; hence, they are useful in the treatment of cardiovascular diseases. Pulses used in the nutrition of obese individuals provide compounds with pancreatic lipase inhibitory properties, thus promoting weight reduction and control. © 2023 Society of Chemical Industry.

Game changers for meat and masculinity? Male athletes' perspectives on mixed and plant-based diets

The dietary choices of male athletes are increasingly a topic of moral and nutritional debate. Though it has long been a consensus that athletes require animal products to advance their athletic goals, this understanding is now challenged in academic and popular sources based on nutritional evidence and concern about the environmental impacts of animal products. In order to better understand how (semi-)professional male athletes perceive plant-based diets and diets containing animal products, thirteen semi-structured interviews were conducted with male athletes competing nationally and internationally, including mixed and plant-based eaters. Interviews were analysed through reflexive thematic analysis, in line with a critical, qualitative research methodology. Justifications for meat, situated knowledge and masculinity were used as theoretical lenses. Our analysis shows how athletes reproduce nutritional claims about the necessity of protein for athletes, but disagree on the suitability of plant-based sources. This nutritional discourse derives from a broad range of sources, including professional nutritionists, friends, online influencers, and media. Second, when explaining their own food practices, food being 'nice' and 'normal' - common justifications for meat as evidenced in the 4N theory - often supersede necessity. Embedding these views in their everyday lives as athletes shows that food environments and shared eating practices fortify a mixed diet as normal, and plant-based diets as anomalous. It further shows how the view of meat being normal is subject to shifting masculinity norms. Interviewees reject meat eating as normal and masculine for men, while male athletes who show dedication, constraint, and knowledge in a plant-based diet are viewed positively. As role models for diet and masculinity, this has implications for a potential role of athletes in a societal transition towards lower consumption of animal products.

Prevention and Treatment of Retinal Vein Occlusion: The Role of Diet-A Review

Retinal vein occlusion (RVO) is the second most common retinal disorder. In comparison to diabetic retinopathy or age-related macular degeneration, RVO is usually an unexpected event that carries a greater psychological impact. There is strong evidence to suggest that cardiovascular diseases are the most common risk factors in this pathology and it has long been known that a higher consumption of fish, nuts, fruits, and vegetables has a protective effect against these types of conditions. In the last several years, interest in plant-based diets has grown in both the general population and in the scientific community, to the point to which it has become one of the main dietary patterns adopted in Western countries. The aim of this review is to investigate the potential impact of macro- and micronutrients on retinal vein occlusion.

Efficacy and utility of a tool for both measurement of vitamin B6, B12, D, folate and iron status and assessment of diet quality in athletes

NutriProfiel® is a tool to measure micronutrient status and to assess diet quality. It consists of measurement of micronutrient status in blood and a short food frequency questionnaire (FFQ) ('Eetscore-FFQ'). Based on the results, individuals receive a dietary advice. In this study, we evaluated the application of NutriProfiel in athletes ('NutriProfiel-Sport') by assessing the coverage of nutrient intake of the Eetscore-FFQ (part 1) and by evaluating athlete's dietary behaviour after using NutriProfiel-Sport and their satisfaction with this tool (part 2). For part 1, data of 419 athletes were used. We evaluated the coverage of nutrient intake of the Eetscore-FFQ using first and second MOMents (MOM1 and MOM2) sum scores of food items in the questionnaire. Forty-eight athletes were involved in part 2. They gave blood samples for micronutrient status measurement and were asked to complete the Eetscore-FFQ at baseline and after 3 months, as well as a questionnaire on their satisfaction with NutriProfiel-Sport. Results showed that for most nutrients, MOM1 and MOM2 scores were above 80 %, meaning that nutrient intake was sufficiently covered by the Eetscore-FFQ. No difference in diet quality was observed between baseline and after 3 months. Nevertheless, a majority of athletes reported the NutriProfiel-Sport results and advice as useful. On a scale from 0 to 10, NutriProfiel-Sport was graded with a mean (±sd) score of 7⋅6 (±0⋅8). In conclusion, NutriProfiel-Sport is a potential valuable and appreciated tool for athletes and the Eetscore-FFQ as part of this tool sufficiently covers nutrient intake in athletes.

Faba Bean Processing: Thermal and Non-Thermal Processing on Chemical, Antinutritional Factors, and Pharmacological Properties

The food industry, academia, food technologists, and consumers have become more interested in using faba bean seeds in the formulation of new products because of their nutritional content, accessibility, low costs, environmental advantages, and beneficial impacts on health. In this review, a systematic and up-to-date report on faba bean seeds' antinutrients and bioactive and processing techniques is comprehensively presented. The chemical composition, including the oil composition and carbohydrate constituents, is discussed. Factors influencing the reduction of antinutrients and improvement of bioactive compounds, including processing techniques, are discussed. Thermal treatments (cooking, autoclaving, extrusion, microwaving, high-pressure processing, irradiation) and non-thermal treatments (soaking, germination, extraction, fermentation, and enzymatic treatment) are identified as methods to reduce the levels of antinutrients in faba bean seeds. Appropriate processing methods can reduce the antinutritional factors and enrich the bioactive components, which is useful for the seeds' efficient utilization in developing functional foods. As a result, this evaluation focuses on the technologies that are employed to reduce the amounts of toxins in faba bean seeds. Additionally, a comparison of these methods is performed in terms of their advantages, disadvantages, viability, pharmacological activity, and potential for improvement using emerging technologies. Future research is expected in this area to fill the knowledge gap in exploiting the nutritional and health benefits of faba bean seeds and increase the utilization of faba bean seeds for different applications.

Effect of Dietary Approaches on Glycemic Control in Patients with Type 2 Diabetes: A Systematic Review with Network Meta-Analysis of Randomized Trials

BACKGROUND

Dietary patterns play a critical role in diabetes management, while the best dietary pattern for Type 2 diabetes (T2DM) patients is still unclear. The aim of this network meta-analysis was to compare the impacts of various dietary approaches on the glycemic control of T2DM patients.

METHODS

Relevant studies were retrieved from PubMed, Embase, Web of Knowledge, Cochrane Central Register of Controlled Trials (CENTRAL), and other additional records (1949 to 31 July 2022). Eligible RCTs were those comparing different dietary approaches against each other or a control diet in individuals with T2DM for at least 6 months. We assessed the risk of bias of included studies with the Cochrane risk of bias tool and confidence of estimates with the Grading of Recommendations Assessment, Development, and Evaluation approach for network meta-analyses. In order to determine the pooled effect of each dietary approach relative to each other, we performed a network meta-analysis (NMA) for interventions for both HbA1c and fasting glucose, which enabled us to estimate the relative intervention effects by combing both direct and indirect trial evidence.

RESULTS

Forty-two RCTs comprising 4809 patients with T2DM were included in the NMA, comparing 10 dietary approaches (low-carbohydrate, moderate-carbohydrate, ketogenic, low-fat, high-protein, Mediterranean, Vegetarian/Vegan, low glycemic index, recommended, and control diets). In total, 83.3% of the studies were at a lower risk of bias or had some concerns. Findings of the NMA revealed that the ketogenic, low-carbohydrate, and low-fat diets were significantly effective in reducing HbA1c (viz., -0.73 (-1.19, -0.28), -0.69 (-1.32, -0.06), and -1.82 (-2.93, -0.71)), while moderate-carbohydrate, low glycemic index, Mediterranean, high-protein, and low-fat diets were significantly effective in reducing fasting glucose (viz., -1.30 (-1.92, -0.67), -1.26 (-2.26, -0.27), -0.95 (-1.51, -0.38), -0.89 (-1.60, -0.18) and -0.75 (-1.24, -0.27)) compared to a control diet. The clustered ranking plot for combined outcomes indicated the ketogenic, Mediterranean, moderate-carbohydrate, and low glycemic index diets had promising effects for controlling HbA1c and fasting glucose. The univariate meta-regressions showed that the mean reductions of HbA1c and fasting glucose were only significantly related to the mean weight change of the subjects.

CONCLUSIONS

For glycemic control in T2DM patients, the ketogenic diet, Mediterranean diet, moderate-carbohydrate diet, and low glycemic index diet were effective options. Although this study found the ketogenic diet superior, further high-quality and long-term studies are needed to strengthen its credibility.

Dietary Recommendations for Ethiopians on the Basis of Priority Diet-Related Diseases and Causes of Death in Ethiopia: An Umbrella Review

Food-based dietary guidelines (FBDG) need to be evidence-based. As part of the development of Ethiopian FBDG, we conducted an umbrella review to develop dietary recommendations. Protein-energy malnutrition (PEM), deficiencies of vitamin A, zinc, calcium, or folate, cardiovascular diseases (CVD), and type 2 diabetes mellitus (T2DM) were selected as a priority. Systematic reviews were eligible if they investigated the impact of foods, food groups, diet, or dietary patterns on priority diseases. After a search, 1513 articles were identified in PubMed, Scopus, and Google Scholar published from January 2014 to December 2021. The results showed that 19 out of 164 systematic reviews reported the impact of diet on PEM or micronutrient deficiencies. Daily 30-90 g whole-grain consumption reduces risk of CVD and T2DM. Pulses improve protein status, and consuming 50-150 g/d is associated with a reduced incidence of CVD and T2DM. Nuts are a good source of minerals, and consuming 15-35 g/d improves antioxidant status and is inversely associated with CVD risk. A daily intake of 200-300 mL of milk and dairy foods is a good source of calcium and contributes to bone mineral density. Limiting processed meat intake to <50 g/d reduces CVD risk. Fruits and vegetables are good sources of vitamins A and C. CVD and T2DM risks are reduced by consuming 200-300 g of vegetables plus fruits daily. Daily sugar consumption should be below 10% of total energy to lower risk of obesity, CVD, and T2DM. Plant-based fat has favorable nutrient profiles and modest saturated fat content. The association of saturated fatty acids with CVD and T2DM is inconclusive, but intake should be limited because of the low-density lipoprotein cholesterol-raising effect. Plant-based diets lower risk of CVD and T2DM but reduce micronutrient bioavailability. The review concludes with 9 key dietary recommendations proposed to be implemented in the Ethiopian FBDG. This review was registered at PROSPERO (CRD42019125490).

Nutritional Status of Vegetarian Patients Before and After Bariatric Surgery: a Monocentric Retrospective Observational Case-Control Study

The obesity pandemic is associated with an increasing number of bariatric surgeries which allow improvement in obesity-related comorbidities and life expectancy but potentially induce nutritional deficiencies. Vegetarianism becomes more and more popular and exposes as well to vitamin and micronutrient deficiencies. Only one study has explored the impact of vegetarianism on the preoperative nutritional status of eligible patients for bariatric surgery, but none in postoperative care.

MATERIALS AND METHODS

We conducted a retrospective case-control study in our cohort of bariatric patients, matching 5 omnivores for each vegetarian. We compared their biological profile regarding vitamin and micronutrient blood levels before and 3, 6, 12, and 30 months after surgery.

RESULTS

We included 7 vegetarians including 4 lacto-ovo-vegetarians (57%), 2 lacto-vegetarians (29%), and one lacto-ovo-pesco-vegetarian (14%). Three years after surgery with equivalent daily standard vitamin supplementation, the two groups showed a similar biological profile including blood levels of ferritin (p = 0.6), vitamin B1 (p = 0.1), and B12 (p = 0.7), while the total median weight loss at 3 years was comparable (39.1% [27.0-46.6] in vegetarians vs 35.7% [10.5-46.5] in omnivores, p = 0.8). We observed no significant difference between vegetarians and omnivores before surgery regarding comorbidities and nutritional status.

CONCLUSION

It seems that, after bariatric surgery, vegetarian patients taking a standard vitamin supplementation do not show an increased risk of nutritional deficiencies compared to omnivores. However, a larger study with a longer follow-up is needed to confirm these data, including an evaluation of different types of vegetarianism such as veganism.

Nutritional Profile of Commercialized Plant-Based Meat: An Integrative Review with a Systematic Approach

Given the high cost of production of animal-based meats and the increase in the number of adepts of meatless diets, the need for plant-based meat substitutes is growing. In this prosperously growing market, there is a lack of knowledge about the nutritional value of these meat substitutes and their ingredients. This study aims to review the nutritional composition and ingredients of meat substitutes commercialized worldwide. An integrative review was performed with a systematic literature search in PubMed, EMBASE, Scopus, Science Direct, Web of Science, and 11 studies were selected to compose the sample of this review. Data on meat substitutes' nutritional composition and ingredients from different categories were collected and analyzed. The results showed that meat substitutes commonly present lower energy values and higher amounts of carbohydrates and dietary fiber. Protein values varied according to the meat substitute category, with some showing a higher concentration than others, more specifically in substitutes for bovine meat. Higher values were found in the Pieces category and lower in Seafood substitutes. Unlike animal meat, vegan meat has a proportion of carbohydrates higher than protein in most samples, except for chicken substitutes. Meat substitutes presented similar total and saturated fat content compared to their animal-based counterparts. Higher amounts of fat were found in the "Various" category and lower in "Pieces". Ingredients such as soy, pea, and wheat were the primary protein sources in meat substitutes, and vegetable oils were their primary fat source. Methylcellulose, various gums, and flavorings were the most used food additives. In general, meat substitutes presented high concentrations of sodium, possibly collaborating with an excessive sodium intake, highlighting the need for developing sodium-reduced or sodium-free alternatives. Most of the included samples did not describe the concentration of iron, zinc, and vitamin B12. Further studies are needed to develop meat substitutes with better nutritional composition, fulfilling the need for equivalent substitutes for animal-based meat.

Effects of experimentally induced self-affirmation on the openness to meat reduction and alternative protein sources

Introduction

Consumption of animals entails disregarding the pain of sentient beings, and acknowledging this can threaten an individual's image of oneself as a moral person. Also, abstaining from meat in a meat-eating culture can threaten an individual's valued group identity. Previous research on inter-group relations suggests that self-affirmation, affirmation of personally or collectively important values, can help individuals alleviate self-threats since it enhances one's global self-image and decreases threat perceptions.

Methods

We tested for potential effects of self-affirmation on openness toward reducing meat consumption in an experimental study. Participants (N = 277) were randomized into an individual affirmation, group affirmation, or a control condition. Individual affirmation participants ranked a list of values and then wrote a short paragraph about their first-ranked value. Group affirmation participants did a similar task, focusing on the values of their ethnic group, while participants in the control condition had an unrelated task of ranking their color preferences. Participants then read a persuasive message presenting health risks related to meat consumption and the health benefits of reducing meat. Finally, they indicated their openness toward reducing meat consumption and acceptability of plant-based alternatives and lab-grown meat.

Results and Discussion

Results show that affirmed participants expressed more readiness to reconsider their meat consumption habits, reduced perceptions of vegetarianism as a threat to the local culture, and more positive perceptions of the idea of lab-grown meat. However, self-esteem and frequency of meat consumption pose important limitations to the experimental effects. We discuss the findings from the perspective of self-and collective identity threats and the potential of self-affirmations to create a more open debate about animal product consumption.

Do urban tourists prefer vegetarianism? An urban-rural comparison of vegetarian consumption in China

The adoption of a vegetarian diet might have public health and environmental benefits. However, little is known about urban and rural Generation Z tourists' attitudes toward vegetarianism or vegetarian consumption within the Chinese urban and rural settings. Hence, to address this gap, the present study adopted a sequential and mixed research approach based on a survey (n = 212) and laddering interviews (n = 20) to validate post-millennial tourists' motives for adopting a vegetarian diet. The results identified the top four motives as environmental protection and resource conservation, ethical consideration, personal taste and choice, and personal healthcare issues. The top four barriers to vegetarianism were unavailability and limited choice, peer pressure, traditional prejudice/habit, and the inability to change. The results also demonstrated that both rural and urban tourists adopt vegetarianism mainly for environmental protection and ethical consideration, a subtle difference between them is that urban vegetarians emphasized ethical considerations more but rural ones emphasized food and variety. Urban consumers considered unavailability and limited choice as the topmost barriers to being vegetarian, while rural vegetarians found traditional prejudice to be restricting. Due to traditional dietary habits and peer influence, rural tourists face many more challenges when adopting a vegetarian diet. Understanding the perceived benefits and barriers to being vegetarian in different regions will not only enrich the theory of food nutrition but also expand Generation Z tourists' consumption behavior and practices.

Environmental impacts and diet quality of popular diet models compared to Turkey's national nutrition guidelines

AIMS

This study aimed to compare the environmental impacts and diet qualities of popular diet models with the recommendations of the Turkish national dietary guidelines.

METHODS

Seven-day isocaloric (8368 kJ) diet models were created taking into account the Mediterranean, Atkins (20/40/100), Ornish, Zone diets, and Turkey Dietary Guidelines-2015 recommendations with different food and nutrient contents. Water footprints were evaluated using the global water footprint standards. Greenhouse gas emissions were evaluated using carbon footprint factors compiled as a result of meta-analyses of life cycle analysis studies in the literature. In addition, the quality of diets was evaluated with the Diet Quality Index-International.

RESULTS

Atkins20 diet model had the most harmful environmental impact (greenhouse gas emissions 8.74 kg CO₂ -eq/per/day and total water footprint 7731 L/per/day), whereas Ornish and Mediterranean diet models (greenhouse gas emissions 2.2/3.07 kg CO₂ -eq/per/day and total water footprints 3184/3675 L/per/day, respectively) had less harmful environmental impact. The highest Diet Quality Index-International score was in the Ornish diet model while the lowest Diet Quality Index-International was in the Atkins20 diet model.

CONCLUSION

Ornish and Mediterranean diet models had less harmful environmental impacts, which contributed to sustainable nutrition. The importance of diet quality and environmental impacts should be kept in mind when evaluating diet models to ensure sustainable nutrition.

Lower Non-Heme Iron Absorption in Healthy Females from Single Meals with Texturized Fava Bean Protein Compared to Beef and Cod Protein Meals: Two Single-Blinded Randomized Trials

Meat analogs based on plant protein extracts are rising in popularity as meat consumption declines. A dietary shift away from meat, which has a high iron bioavailability, may have a negative effect on the amount of iron absorbed from the diet. Iron absorption from legumes cultivated in regions not suitable for soy production, such as fava bean, has not yet been explored. The aim of this study was to evaluate non-heme iron absorption from a meal with texturized fava bean protein compared to beef and cod protein meals. The study included two single-blinded iron isotope trials in healthy Swedish women of the ages 18–45 years, each of whom served as their own control. The participants were served matched test meals containing beef and fava bean protein (Study 1) or cod and fava bean protein (Study 2) with radiolabeled non-heme iron 55Fe and 59Fe. The absorption of non-heme iron from test meals was measured by whole-body counting and erythrocyte incorporation. The absorption of non-heme iron, measured as erythrocyte incorporation ratio, from beef protein meal was 4.2 times higher compared to texturized fava bean meal, and absorption from cod protein meal was 2.7 times higher compared to the fava bean meal. The adjusted non-heme iron absorption, normalized to a 40% reference dose uptake, was 9.2% for cod protein meal, 21.7% for beef protein meal, and 4.2% for texturized fava bean meal. A fava bean protein meal has markedly lower iron bioavailability in healthy females compared with a meal of beef or cod protein. Therefore, a dietary shift from meat and fish protein to fava bean protein may increase the risk of iron deficiency.

Dietary Change and Global Sustainable Development Goals

Food production for human consumption is a leading cause of environmental damage in the world and yet over two billion people suffer from malnutrition. Several studies have presented evidence that changes in dietary patterns across the world can lead to win-win outcomes for environmental and social sustainability and can complement ongoing technological and policy efforts to improve the efficiency of agricultural production. However, the existing evidence have been compiled in “silos” by a large range of researchers across several disciplines using different indicators. The aim of this quantitative review is to bring together the existing knowledge on heterogeneity of current dietary patterns across the world and how a transition toward healthy diets in different countries can aid in progress toward multiple global Sustainable Development Goals (SDGs). We first summarize the nutritional quality, economic cost, and environmental footprint of current diets of over 150 countries using multiple indicators. Next, we review which shifts in dietary patterns across different world regions can help toward achievement of SDG2 (Zero hunger), SDG3 (Good health and wellbeing), SDG 6 (Clean water and sanitation), SDG13 (Climate action), SDG14 (Life below water), and SDG15 (Life on land). Finally, we briefly discuss how to enable the shift toward sustainable dietary patterns and identify the research and data gaps that need to be filled through future efforts. Our analysis reveals that dietary change is necessary in all countries as each one has unique priorities and action items. For regions such as Sub-Saharan Africa and South Asia, increased intake of nutrient dense foods is needed to address deficiency of essential nutrients like folate, potassium, and vitamin A. For North America and Europe, shifting toward more plant-based diets would be healthier and simultaneously reduce the per capita environmental footprints. The results can be useful for policymakers in designing country-specific strategies for adoption of sustainable dietary behaviors and for food industry to ensure the supply of sustainable food items customized with regions' need.

The Association Between Plant-Based Diet Indices and Obesity and Metabolic Diseases in Chinese Adults: Longitudinal Analyses From the China Health and Nutrition Survey

Background

A wide range of health benefits are associated with consuming a diet high in plant-based foods. Diet quality can be accurately assessed using plant-based diet indices, however there is inadequate evidence that plant-based diet indices are linked to obesity, hypertension, and type 2 diabetes (T2D), especially in Chinese cultures who have traditionally consumed plant-rich foods.

Methods

The data came from the China Nutrition and Health Survey. Overall, 11,580 adult participants were enrolled between 2004 and 2006 and followed up until 2009 or 2015 (follow-up rate: 73.4%). Dietary intake was assessed across three 24-h recalls, and two plant-based dietary indices [overall plant-based diet indice (PDI) and healthy plant-based diet indice (hPDI)] were calculated using China Food Composition Code and categorized into quintiles. The study's endpoints were overweight/obesity, hypertension, and T2D. The Hazard ratio (HR) and dose-response relationship were assessed using the Cox proportional risk model and restricted cubic splines. The areas under the curve of the receiver operating characteristic curve analyses were used to evaluate the predictive performance of the PDI and hPDI.

Results

During the median follow-up period of more than 10 years, 1,270 (33.4%), 1,509 (31.6%), and 720 (11.5%) participants developed overweight / obesity, hypertension, and T2D, respectively. The higher PDI score was linked with a reduced risk of overweight/obesity [HR: 0.71 (95% CI: 0.55–0.93), P-trend <0.001], hypertension [HR: 0.63 (95% CI: 0.51–0.79), P-trend <0.001], and T2D [HR: 0.79 (95% CI: 0.72–0.87), P-trend <0.001]. The hPDI score was inversely associated with overweight/obesity [HR: 0.79 (95% CI: 0.62–0.98), P-trend = 0.02] and T2D [HR: 0.84 (95% CI: 0.75–0.93), P-trend = 0.001]. In the aged <55-year-old group, subgroup analysis indicated a significant negative association between PDI/hPDI and overweight/obesity, hypertension, and T2D. There was no significant difference in the areas under the curve of the fully adjusted obesity, hypertension, and diabetes prediction models between PDI and hPDI.

Conclusion

The PDI and hPDI scores were very similar in application in Chinese populations, and our findings highlight that adherence to overall plant-based diet index helps to reduce the risk of T2D, obesity, and hypertension in Chinese adults who habitually consume plant-based foods, especially for those aged <55 year. Further understanding of how plant-based diet quality is associated with chronic disease will be needed in the future, which will help develop dietary strategies to prevent diabetes, hypertension, and related chronic diseases.

Combined Low Plant and High Animal Dietary Pattern Is Associated with a Lower Risk of Anemia among Dyslipidemic Adult Women in Taiwan: A Retrospective Study from 2001 to 2015

Anemia and dyslipidemia often occurs in premenopausal women. This study investigated the association between dietary patterns and anemia among dyslipidemic women in Taiwan. This study recruited 22,631 dyslipidemic women aged 20-45 years between 2001 and 2015. The dietary assessment was collected by a validated food frequency questionnaire. The biochemical data including blood lipids, red blood cells, hemoglobin, hematocrit, and C-reactive protein (CRP) were retrieved from the database. Women with a combined high plant diet (HP) and low animal diet (LA) were associated with a lower prevalence of obesity (11.7%), central obesity (16.0%), high total cholesterol (16.4%), and high low-density lipoprotein cholesterol (11.9%), and had lower hemoglobin (12.9 ± 1.4 g/dL), hematocrit (38.8 ± 3.6%), and CRP levels (20.6 ± 31.4 nmol/L). The low plant diet (LP) + high animal diet (HA) pattern was negatively associated with moderate to severe anemia (OR: 0.76, 95% CI: 0.64-0.92, p = 0.004) compared to the low plant diet (LP) + low animal diet (LA) pattern. However, the HP + LA pattern was positively correlated with moderate to severe anemia (OR: 1.22, 95% CI: 1.04-1.43, p = 0.015). In conclusion, a low plant and high animal diet plays a role in preventing anemia development among dyslipidemic women.

Dietary Iron and the Elite Dancer

Dancers are an athlete population at high risk of developing iron deficiency (ID). The aesthetic nature of the discipline means dancers potentially utilise dietary restriction to meet physique goals. In combination with high training demands, this means dancers are susceptible to problems related to low energy availability (LEA), which impacts nutrient intake. In the presence of LEA, ID is common because of a reduced mineral content within the low energy diet. Left untreated, ID becomes an issue that results in fatigue, reduced aerobic work capacity, and ultimately, iron deficient anaemia (IDA). Such progression can be detrimental to a dancer’s capacity given the physically demanding nature of training, rehearsal, and performances. Previous literature has focused on the manifestation and treatment of ID primarily in the context of endurance athletes; however, a dance-specific context addressing the interplay between dance training and performance, LEA and ID is essential for practitioners working in this space. By consolidating findings from identified studies of dancers and other relevant athlete groups, this review explores causal factors of ID and potential treatment strategies for dancers to optimise absorption from an oral iron supplementation regime to adequately support health and performance.

Nutrition Benefits and Considerations for Whole Foods Plant-Based Eating Patterns

Whole foods plant-based approaches to eating place an emphasis on the intake of fruits, vegetables, whole grains, and legumes and have many health benefits. While there are key nutrients and phytochemicals that can contribute to the purported health benefits, practitioners and patients should also be advised of key nutrients for which intake may be compromised when following this dietary pattern. With careful planning and utility of dietary supplements, individuals can achieve optimal intake of calcium, iron, vitamin D, omega 3 fatty acid-docosahexaenoic acid (DHA), and vitamin B12 and experience the health benefits of a dietary fiber and a host of phytochemicals. This article presents the health benefits of these food substances and approaches for overcoming nutrients of concern when following whole food plant-based eating patterns.

Dietary Habits and Self-Reported Health Measures Among Norwegian Adults Adhering to Plant-Based Diets

Background

As plant-based diets is increasing, we aimed to investigate dietary habits, dietary motivation and self-reported health of Norwegian adults who adhere to different types of plant-based diets.

Methods

In 2020, 808 subjects (530 women and 278 men) participated in an online survey, including vegans (8%), lacto-ovo vegetarians (16%), pescatarians (23%), and flexitarians (53%).

Results

Half of the participants reported to consume fruits daily, three quarters consumed vegetables daily, and one quarter consumed whole grain products daily. Half of the participants reported weekly consumption of sweets and salted snacks, and 10% reported daily consumption of sugary drinks. Daily consumption of milk and dairy substitutes were reported by vegans (49%), lacto-ovo vegetarians (33%), pescatarians (32%), and flexitarians (25%). Daily consumption of meat replacement products was reported by vegans (3%), lacto-ovo vegetarians (5%), pescatarians (2%). Reported supplement use was highest among vegans (62%) and lowest among flexitarians (28%). Dietary motivations were driven by environmental (71%), health (64%), and animal welfare (49%) concerns, across all dietary groups. 75% reported their self-perceived health to be good or very good.

Conclusion

We found that Norwegian adults adhering to plant-based diets consumed less fruit, vegetables, and whole grain products, together with more sugar than recommended in the Norwegian dietary guidelines. The participants reported their self-perceived health to be good or very good.

Dietary Patterns and Gut Microbiota: The Crucial Actors in Inflammatory Bowel Disease

It is widely believed that diet and the gut microbiota are strongly related to the occurrence and progression of inflammatory bowel disease (IBD), but the effects of the interaction between dietary patterns and the gut microbiota on IBD have not been well elucidated. In this article, we aim to explore the complex relation between dietary patterns, gut microbiota, and IBD. We first comprehensively summarized the dietary patterns associated with IBD and found that dietary patterns can modulate the occurrence and progression of IBD through various signaling pathways, including mammalian target of rapamycin (mTOR), mitogen-activated protein kinases (MAPKs), signal transducer and activator of transcription 3 (STAT3), and NF-κB. Besides, the gut microbiota performs a vital role in the progression of IBD, which can affect the expression of IBD susceptibility genes, such as dual oxidase 2 (DUOX2) and APOA-1 , the intestinal barrier (in particular, the expression of tight junction proteins), immune function (especially the homeostasis between effector and regulatory T cells) and the physiological metabolism, in particular, SCFAs, bile acids (BAs), and tryptophan metabolism. Finally, we reviewed the current knowledge on the interaction between dietary patterns and the gut microbiota in IBD and found that dietary patterns modulate the onset and progression of IBD, which is partly attributed to the regulation of the gut microbiota (especially SCFAs-producing bacteria and Escherichia coli). Faecalibacteria as "microbiomarkers" of IBD could be used as a target for dietary interventions to alleviate IBD. A comprehensive understanding of the interplay between dietary intake, gut microbiota, and IBD will facilitate the development of personalized dietary strategies based on the regulation of the gut microbiota in IBD and expedite the era of precision nutritional interventions for IBD.

Effects of Excess Iron on the Retina: Insights From Clinical Cases and Animal Models of Iron Disorders

Iron plays an important role in a wide range of metabolic pathways that are important for neuronal health. Excessive levels of iron, however, can promote toxicity and cell death. An example of an iron overload disorder is hemochromatosis (HH) which is a genetic disorder of iron metabolism in which the body’s ability to regulate iron absorption is altered, resulting in iron build-up and injury in several organs. The retina was traditionally assumed to be protected from high levels of systemic iron overload by the blood-retina barrier. However, recent data shows that expression of genes that are associated with HH can disrupt retinal iron metabolism. Thus, the effects of iron overload on the retina have become an area of research interest, as excessively high levels of iron are implicated in several retinal disorders, most notably age–related macular degeneration. This review is an effort to highlight risk factors for excessive levels of systemic iron build-up in the retina and its potential impact on the eye health. Information is integrated across clinical and preclinical animal studies to provide insights into the effects of systemic iron loading on the retina.