Association of Major Dietary Protein Sources With All-Cause and Cause-Specific Mortality: Prospective Cohort Study

Source of dietary protein alters the abundance of proteases, intestinal epithelial and immune proteins both directly and via interactions with the gut microbiota

Dietary protein has been shown to impact long-term health outcomes differentially depending on its amount and source. It has been suggested that interactions of the gut microbiota with dietary proteins mediate some of the effects of dietary protein on health outcomes. However, it remains unclear what specific host responses drive the health effects of dietary proteins from different plant and animal sources. Additionally, which specific host responses are mediated by interactions of dietary protein source with the gut microbiota and which host responses are caused by dietary proteins directly is not well understood. We used metaproteomics to quantify dietary, host, and microbial proteins in fecal samples of conventional and germ-free mice fed purified dietary protein from six different plant and animal sources, including casein, egg-white, soy, brown rice, pea, and yeast. We characterized differences in the host fecal proteome across the six dietary protein sources as well as between the conventional and germ-free mice for each source to determine how the host responds to the different dietary protein sources and the role of the gut microbiota in mediating these responses. We found that both the source of dietary protein and the presence or absence of the gut microbiota drive the host response to dietary protein source in the fecal host proteome. Host proteins pertaining to immune response, digestion, and barrier function were differentially abundant in different protein sources with and without the gut microbiota. These changes in the host response correlated with changes in microbial composition and differences in protein digestibility. Our results show how dietary protein sources, through their interactions with the gut microbiota, impact several aspects of host physiology.

Plant-Based Diets and Cardiovascular Disease in Older Adults: An Integrative Literature Review

Cardiovascular disease (CVD) is the leading cause of mortality globally, disproportionately impacting older adults. Plant-based diets (PBDs) have emerged as a dietary strategy to mitigate CVD risk, characterized by foods derived from plants and minimal to no animal-derived foods. This integrative review assesses the effectiveness of PBDs for improving CVD risk factors in older adults. A search was conducted in CINAHL, PubMed, and Medline databases for studies of PBDs and CVD risk factors in individuals aged 65 years and older. Quality assessment was performed using the Mixed Methods Appraisal Tool (MMAT). Seventeen publications were analyzed, 7 experimental and 10 non-experimental. All studies showed at least one positive association between PBDs and cardiovascular health in older adults. Findings highlighted significant associations between PBD adherence and reductions in key CVD risk factors, such as low-density lipoprotein cholesterol (LDL-C), blood pressure, and body mass index (BMI), alongside potential benefits in reducing coronary artery calcium and enhancing endothelial function and serum isoflavone concentrations. There is evidence for the potential of PBDs as an effective dietary strategy to prevent the onset and progression of CVD in older adults and reduce the risk of CVD mortality. This review indicates the need for further research. Larger randomized control trials focused on older adults may strengthen the evidence base and guide healthcare recommendations. PBDs should be considered as a part of holistic CVD prevention and management strategies for older adults, encouraging dietary patterns that are rich in fruits, vegetables, legumes, beans, nuts, seeds, and whole grains.

Association between substituting macronutrients and all-cause mortality: a network meta-analysis of prospective observational studies

Background

Suboptimal diet quality is a key risk factor for premature death. Assuming relatively stable energy intake among individuals, changes in nutrient intakes occur by exchanging different nutrients. Therefore we aimed to examine the association of isocaloric substitution of dietary (macro)nutrients with all-cause mortality using network meta-analysis (NMA).

Methods

For this systematic review and NMA of prospective observational studies MEDLINE, Embase, and Scopus were searched from inception to February 13th, 2024. Eligible studies reported substitution analyses for quantity and/or quality of macronutrients, including carbohydrates, proteins, and fatty acids on all-cause mortality. Random-effects NMA were used in order to evaluate the pooled hazard ratios (HR) and 95% confidence intervals (CI) of substituting each included nutrient with another. We assessed risk of bias with the ROBINS-E tool, and the certainty of evidence (CoE) using the Grading of Recommendations Assessment, Development and Evaluations (GRADE) approach. This study is registered with PROSPERO (CRD42023450706).

Findings

Thirty-nine studies with 1,737,644 participants, 395,491 deaths, 297 direct comparisons, and seven nutrient-specific networks were included. Moderate CoE was found for an association with lower mortality risk when replacing 5% of energy intake from carbohydrates with polyunsaturated fatty acids (PUFA; HR: 0.90; 95%CI: 0.84, 0.95), n-6 PUFA (0.85; 0.77, 0.94), n-3 PUFA (0.72; 0.59, 0.86), and plant monounsaturated fatty acids (MUFA; 0.90; 0.85, 0.95), and when replacing 5% of energy from saturated fatty acids (SFA) and trans-fatty acids (TFA), with PUFA, MUFA, and plant-MUFA (HRrange: 0.75 to 0.91). A lower mortality risk was additionally found when 5% of animal-MUFA was replaced with plant-MUFA, and when replacing animal protein, and SFA with plant protein (HRrange: 0.81 to 0.87, moderate CoE).

Interpretation

Our results provide practical knowledge for public health professionals and can inform upcoming dietary guidelines. The beneficial association of increasing PUFA (both n-3 and n-6) and (plant-) MUFA intake while reducing carbohydrates, SFA and TFA, along with replacing animal protein and animal-MUFA with plant-based sources of protein and fat (MUFA) on the all-cause mortality risk, underscores the importance of plant-based dietary recommendations.

Funding

None.

Dietary protein from different sources escapes host digestion and is differentially modified by the microbiota

Protein is an essential macronutrient and variations in its source and quantity have been shown to impact long-term health outcomes. Differential health impacts of dietary proteins from various sources are likely driven by differences in their digestibility by the host and subsequent availability to the intestinal microbiota. However, our current understanding regarding the fate of dietary proteins from different sources in the gut, specifically how component proteins within these sources interact with the host and the gut microbiota, is limited. To determine which dietary proteins are efficiently digested by the host and which proteins escape host digestion and are used by the gut microbiota, we used high-resolution mass spectrometry to quantify the proteins that make up different dietary protein sources before and after digestion in germ-free and conventionally raised mice. Contrary to expectation, we detected proteins from all sources in fecal samples of both germ-free and conventional mice suggesting that even protein sources with a high digestive efficiency make it in part to the colon where they can serve as a substrate for the microbiota. Additionally, we found clear patterns where specific component proteins of the dietary protein sources were used as a preferred substrate by the microbiota or were not as accessible to the microbiota. We found that specific proteins with functions that could impact host health and physiology were differentially enriched in germ-free or conventionally raised mice. These findings reveal large differences in the fate of dietary protein from various sources in the gut that could explain some of their differential health impacts.

Plant foods, healthy plant-based diets, and type 2 diabetes: a review of the evidence

Type 2 diabetes (T2D) is a metabolic chronic disease in which insulin resistance and insufficient insulin production lead to elevated blood glucose levels. The prevalence of T2D is growing worldwide, mainly due to obesity and the adoption of Western diets. Replacing animal foods with healthy plant foods is associated with a lower risk of T2D in prospective studies. In randomized controlled trials, the consumption of healthy plant foods in place of animal foods led to cardiometabolic improvements in patients with T2D or who were at high risk of the disease. Dietary patterns that limit or exclude animal foods and focus on healthy plant foods (eg, fruits, vegetables, whole grains, nuts, legumes), known as healthy, plant-based diets, are consistently associated with a lower risk of T2D in cohort studies. The aim of this review is to examine the differential effects of plant foods and animal foods on T2D risk and to describe the existing literature about the role of healthy, plant-based diets, particularly healthy vegan diets, in T2D prevention and management. The evidence from cohort studies and randomized controlled trials will be reported, in addition to the potential biological mechanisms that seem to be involved.

Substitution of Dairy Products and Risk of Death and Cardiometabolic Diseases: A Systematic Review and Meta-Analysis of Prospective Studies

Substitution models in epidemiologic studies specifying both substitute and substituted food in relation to disease risk may be useful to inform dietary guidelines. A systematic review of prospective observational studies was performed to quantify the risks of all-cause mortality, cardiovascular disease, and type 2 diabetes (T2D) associated with the substitution of dairy products with other foods and between different dairy products. We systematically searched MEDLINE, Embase, and Web of Science until 28th June, 2023. We calculated summary relative risks (SRRs) and 95% confidence intervals (95% CI) in random-effects meta-analyses. We assessed the risk of bias with the Risk Of Bias In Non-randomized Studies - of Exposure (ROBINS-E) tool and certainty of evidence (CoE) using the Grading of Recommendations Assessment, Development, and Evaluations (GRADE) approach. Fifteen studies (with 34 publications) were included. There was moderate CoE that the substitution of low-fat dairy with red meat was associated with a higher risk of mortality, coronary artery disease, and T2D [SRR (95% CI): 1.11 (1.06, 1.16), 1.13 (1.08, 1.18), and 1.20 (1.16, 1.25)]. A higher risk of mortality and T2D was also observed when substituting low-fat dairy with processed meat [SRR (95% CI): 1.19 (1.11, 1.28) and 1.41 (1.33, 1.49); moderate CoE]. A lower mortality risk was associated with the substitution of dairy and yogurt with whole grains [SRR (95% CI): 0.89 (0.84, 0.93) and 0.91 (0.85, 0.97)], and butter with olive oil [SRR (95% CI): 0.94 (0.92, 0.97); all moderate CoE]. Mainly no associations were observed when substituting dairy products against each other on disease and mortality risk. Our findings indicate associations between substituting dairy with red or processed meat and higher disease risk, whereas its substitution with whole grains was associated with a lower risk. However, there is little robust evidence that substituting whole-fat with low-fat dairy is associated with disease risk. (CRD42022303198).

The Role of Diet and Gut Microbiota in Alzheimer's Disease

Alzheimer's disease (AD), the most prevalent form of dementia, is characterized by the accumulation of amyloid-beta (Aβ) plaques and hyperphosphorylated tau tangles. Currently, Alzheimer's disease (AD) impacts 50 million individuals, with projections anticipating an increase to 152 million by the year 2050. Despite the increasing global prevalence of AD, its underlying pathology remains poorly understood, posing challenges for early diagnosis and treatment. Recent research suggests a link between gut dysbiosis and the aggregation of Aβ, the development of tau proteins, and the occurrence of neuroinflammation and oxidative stress are associated with AD. However, investigations into the gut-brain axis (GBA) in the context of AD progression and pathology have yielded inconsistent findings. This review aims to enhance our understanding of microbial diversity at the species level and the role of these species in AD pathology. Additionally, this review addresses the influence of confounding elements, including diet, probiotics, and prebiotics, on AD throughout different stages (preclinical, mild cognitive impairment (MCI), and AD) of its progression.

Dietary Macronutrient Intake and Cardiovascular Disease Risk and Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies

Many epidemiological studies have evaluated the intake of macronutrients and the risk of mortality and cardiovascular disease (CVD). However, current evidence is conflicting and warrants further investigation. Therefore, we carried out an umbrella review to examine and quantify the potential dose-response association of dietary macronutrient intake with CVD morbidity and mortality. Prospective cohort studies from PubMed, Embase, and CENTRAL were reviewed, which reported associations of macronutrients (protein, fat, and carbohydrate) with all-cause, CVD, cancer mortality, or CVD events. Multivariable relative risks (RR) were pooled, and heterogeneity was assessed. The results of 124 prospective cohort studies were included in the systematic review and 101 in the meta-analysis. During the follow-up period from 2.2 to 30 years, 506,086 deaths and 79,585 CVD events occurred among 5,107,821 participants. High total protein intake was associated with low CVD morbidity (RR 0.88, 95% confidence interval 0.82-0.94), while high total carbohydrate intake was associated with high CVD morbidity (1.08, 1.02-1.13). For fats, a high intake of total fat was associated with a decreased all-cause mortality risk (0.92, 0.85-0.99). Saturated fatty acid intake was only associated with cancer mortality (1.10, 1.06-1.14); Both monounsaturated fatty acid (MUFA) and polyunsaturated fatty acids (PUFA) intake was associated with all-cause mortality (MUFA: 0.92, 0.86-0.98; PUFA: 0.91, 0.86-0.96). This meta-analysis supports that protein intake is associated with a decreased risk of CVD morbidity, while carbohydrate intake is associated with an increased risk of CVD morbidity. High total fat intake is associated with a low risk of all-cause mortality, and this effect was different in an analysis stratified by the type of fat.

5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes-2024

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, an interprofessional expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Association between dietary knowledge and muscle mass in Chinese older adults: a cross-sectional and longitudinal study

OBJECTIVES

This study aims to explore the possible association between dietary knowledge and muscle mass in a Chinese population aged 60 years and above.

DESIGN

Cross-sectional and longitudinal studies.

SETTING

Data from the 2006 and 2011 China Health and Nutrition Survey (CHNS) were used for this study.

PARTICIPANTS

A total of 1487 Chinese participants (44.38% males) aged 60 and above in the 2006 survey were included in the cross-sectional study. From the same study population, a total of 1023 participants (46.82% males) with normal muscle mass on the interview date of 2006 were included in the longitudinal study.

OUTCOME MEASURES

Dietary knowledge was accessed by a validated CHNS questionnaire. Appendicular skeletal muscle mass was calculated using a validated anthropometric equation derived from a representative Chinese population. Based on the 2021 Chinese consensus on sarcopenia, the appendicular skeletal muscle mass was categorised as 'normal' or 'low' using sex-specific cut-off values.

RESULTS

The prevalence of low muscle mass in the study population was 31.20%, with a higher prevalence in females (34.22%). People with low muscle mass have a significantly lower dietary knowledge score (mean difference: -1.74, 95% CI -2.20 to -1.29). In the cross-sectional analysis, one score higher in dietary knowledge score was associated with a 4% lower odds of low muscle mass (OR=0.96, 95% CI 0.93 to 0.99). Compared with people in the lowest quartile of dietary knowledge, people in the highest quartile have a 44% lower odds of low muscle mass (OR=0.56, 95% CI 0.35 to 0.91). In the longitudinal analysis, no significant association was found between dietary knowledge and low muscle mass, yet the upper 95% CI was close to one (HR=0.97, 95% CI 0.93 to 1.01).

CONCLUSIONS

Sufficient dietary knowledge may play a protective role in maintaining normal muscle mass in Chinese adults aged 60 or above.

Substitution of animal-based with plant-based foods on cardiometabolic health and all-cause mortality: a systematic review and meta-analysis of prospective studies

BACKGROUND

There is growing evidence that substituting animal-based with plant-based foods is associated with a lower risk of cardiovascular diseases (CVD), type 2 diabetes (T2D), and all-cause mortality. Our aim was to summarize and evaluate the evidence for the substitution of any animal-based foods with plant-based foods on cardiometabolic health and all-cause mortality in a systematic review and meta-analysis.

METHODS

We systematically searched MEDLINE, Embase, and Web of Science to March 2023 for prospective studies investigating the substitution of animal-based with plant-based foods on CVD, T2D, and all-cause mortality. We calculated summary hazard ratios (SHRs) and 95% confidence intervals (95% CI) using random-effects meta-analyses. We assessed the certainty of evidence (CoE) using the GRADE approach.

RESULTS

In total, 37 publications based on 24 cohorts were included. There was moderate CoE for a lower risk of CVD when substituting processed meat with nuts [SHR (95% CI): 0.73 (0.59, 0.91), n = 8 cohorts], legumes [0.77 (0.68, 0.87), n = 8], and whole grains [0.64 (0.54, 0.75), n = 7], as well as eggs with nuts [0.83 (0.78, 0.89), n = 8] and butter with olive oil [0.96 (0.95, 0.98), n = 3]. Furthermore, we found moderate CoE for an inverse association with T2D incidence when substituting red meat with whole grains/cereals [0.90 (0.84, 0.96), n = 6] and red meat or processed meat with nuts [0.92 (0.90, 0.94), n = 6 or 0.78 (0.69, 0.88), n = 6], as well as for replacing poultry with whole grains [0.87 (0.83, 0.90), n = 2] and eggs with nuts or whole grains [0.82 (0.79, 0.86), n = 2 or 0.79 (0.76, 0.83), n = 2]. Moreover, replacing red meat for nuts [0.93 (0.91, 0.95), n = 9] and whole grains [0.96 (0.95, 0.98), n = 3], processed meat with nuts [0.79 (0.71, 0.88), n = 9] and legumes [0.91 (0.85, 0.98), n = 9], dairy with nuts [0.94 (0.91, 0.97), n = 3], and eggs with nuts [0.85 (0.82, 0.89), n = 8] and legumes [0.90 (0.89, 0.91), n = 7] was associated with a reduced risk of all-cause mortality.

CONCLUSIONS

Our findings indicate that a shift from animal-based (e.g., red and processed meat, eggs, dairy, poultry, butter) to plant-based (e.g., nuts, legumes, whole grains, olive oil) foods is beneficially associated with cardiometabolic health and all-cause mortality.

Maintaining brain health across the lifespan

Across the lifespan, the human body and brain endure the impact of a plethora of exogenous and endogenous factors that determine the health outcome in old age. The overwhelming inter-individual variance spans between progressive frailty with loss of autonomy to largely preserved physical, cognitive, and social functions. Understanding the mechanisms underlying the diverse aging trajectories can inform future strategies to maintain a healthy body and brain. Here we provide a comprehensive overview of the current literature on lifetime factors governing brain health. We present the growing body of evidence that unhealthy alimentary regime, sedentary behaviour, sleep pathologies, cardio-vascular risk factors, and chronic inflammation exert their harmful effects in a cumulative and gradual manner, and that timely and efficient intervention could promote healthy and successful aging. We discuss the main effects and interactions between these risk factors and the resulting brain health outcomes to follow with a description of current strategies aiming to eliminate, treat, or counteract the risk factors. We conclude that the detailed insights about modifiable risk factors could inform personalized multi-domain strategies for brain health maintenance on the background of increased longevity.

Dairy Foods: Beneficial Effects of Fermented Products on Cardiometabolic Health

PURPOSE OF REVIEW

This review of recent observational studies and understanding of the complex nature of dairy foods is intended to reappraise the effects of different types of dairy foods on cardiovascular disease (CVD).

RECENT FINDINGS

Recent guidelines from major cardiovascular societies suggest that apart from the adverse effect of butter, consumption of more complex dairy products notably fermented varieties and yogurt in particular, appear to be inversely associated with outcomes of CVD and type 2 diabetes (T2D). Reduced fat in dairy food remains preferred for people at increased CVD risk. Changed evidence has led to new advice regarding consumption of some dairy foods. The apparent beneficial effects of fermented milk products, particularly yogurt, allow for increased consumption of nutritious staple foods. Recent national guidelines reflect this view.

How to Keep the Balance between Red and Processed Meat Intake and Physical Activity Regarding Mortality: A Dose-Response Meta-Analysis

BACKGROUND

Non-communicable diseases have become a major threat to public health, with cardiovascular diseases (CVDs) and cancer being the top two causes of death each year.

OBJECTIVE

Our objective is to evaluate the balanced association between the effect of red and processed meat intake on the risk of death and the effect of physical activity on the risk of mortality, where the risk of death includes all causes, CVDs, and cancers.

METHODS

We searched electronic databases, including PubMed, ISI Web of Science, Embase, and the Cochrane Library, for prospective studies reporting risk estimates for the association between the intake of red and processed meat, walking, and muscle-strengthening activity (MSA) and the risk of mortality from all causes, CVDs, and cancer. We extracted fully adjusted effect estimates from original studies and performed a summary analysis using the fixed and random-effect models.

RESULTS

A conventional meta-analysis showed that red meat and processed meat were positively associated with the risk of mortality, and daily steps and MSA were negatively associated with the risk of death. Further analysis of the dose-response relationship showed that a risk reduction (20%) from 39.5 min/week of MSA or 4100 steps/d was equivalent to an increased risk of all-cause mortality from a daily intake of 103.4 g/d of red meat or 50 g/d of processed meat. The risk was further decreased as the number of steps per day increased, but the risk reversed when the MSA exceeded the threshold (39.5 min/week).

CONCLUSIONS

Adherence to physical activity is an effective way to reduce the risk of mortality due to meat intake. However, the total intake of red meat and processed meat should be controlled, especially the latter. Walking is recommended as the main daily physical activity of choice, while MSAs are preferred when time is limited, but it should be noted that longer MSAs do not provide additional benefits.

Amino acid intake with protein food source and incident dyslipidemia in Korean adults from the Ansan and Ansung Study and the Health Examinee Study

Background

Dyslipidemia is a major risk factor for cardiovascular diseases and appropriate intake of amino acids may be helpful for the management of dyslipidemia. However, evidence of an association between amino acid intake and dyslipidemia in Korean adults is limited.

Objective

The purpose of this study was to investigate how the incidence of dyslipidemia in Korean adults is associated with the consumption of amino acids, essential and nonessential types, as well as the sources of these amino acids from food.

Methods

Data from 35,478 study participants without dyslipidemia at baseline from the Ansan and Ansung Study and the Health Examinee Study were used for the analysis. Dyslipidemia and its components such as hypertriglyceridemia, hypercholesterolemia, hyper-low-density lipoprotein (LDL) cholesterolemia and hypo-high-density lipoprotein (HDL) cholesterolemia were the main outcome in this study. The participants were categorized into quartiles, based on the intake of amino acids and plant-/animal-based proteins.

Results

On average, the follow-up period lasted for 5.7 years. The two major food groups that contributed to one-half of the intake for each type of amino acid were whole grain mixed rice and white rice. Compared to the lowest quartile group, the highest quartile groups of essential amino acid intake [men: hazard ratio (HR) = 0.78; 95% confidence interval (CI), 0.63-0.97; P for trend = 0.0088; women: HR = 0.86; 95% CI, 0.76-0.99; P for trend = 0.0201] and nonessential amino acid intake (men: HR = 0.75; 95% CI, 0.60-0.94; P for trend = 0.0069; women: HR = 0.81; 95% CI, 0.71-0.93; P for trend = 0.0024) had a decreased risk of dyslipidemia. Plant-based protein intake had a negative association and animal-based protein intake had a nonsignificant association with dyslipidemia after adjustment for energy-adjusted fat intake. Furthermore, the essential and nonessential amino acid intake showed stronger negative associations with dyslipidemia after further adjustment for energy-adjusted fat intake.

Conclusion

To conclude, the intake of amino acids may have a protective effect against dyslipidemia in Korean adults who are aged 40 years or older, regardless of their protein food sources.

Red meat consumption, cardiovascular diseases, and diabetes: a systematic review and meta-analysis

AIMS

Observational studies show inconsistent associations of red meat consumption with cardiovascular disease (CVD) and diabetes. Moreover, red meat consumption varies by sex and setting, however, whether the associations vary by sex and setting remains unclear.

METHODS AND RESULTS

This systematic review and meta-analysis was conducted to summarize the evidence concerning the associations of unprocessed and processed red meat consumption with CVD and its subtypes [coronary heart disease (CHD), stroke, and heart failure], type two diabetes mellitus (T2DM), and gestational diabetes mellitus (GDM) and to assess differences by sex and setting (western vs. eastern, categorized based on dietary pattern and geographic region). Two researchers independently screened studies from PubMed, Web of Science, Embase, and the Cochrane Library for observational studies and randomized controlled trials (RCTs) published by 30 June 2022. Forty-three observational studies (N = 4 462 810, 61.7% women) for CVD and 27 observational studies (N = 1 760 774, 64.4% women) for diabetes were included. Red meat consumption was positively associated with CVD [hazard ratio (HR) 1.11, 95% confidence interval (CI) 1.05 to 1.16 for unprocessed red meat (per 100 g/day increment); 1.26, 95% CI 1.18 to 1.35 for processed red meat (per 50 g/day increment)], CVD subtypes, T2DM, and GDM. The associations with stroke and T2DM were higher in western settings, with no difference by sex.

CONCLUSION

Unprocessed and processed red meat consumption are both associated with higher risk of CVD, CVD subtypes, and diabetes, with a stronger association in western settings but no sex difference. Better understanding of the mechanisms is needed to facilitate improving cardiometabolic and planetary health.

Gut Microbiota and its Metabolites: Bridge of Dietary Nutrients and Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive cognitive impairment and neuroinflammation. Recent research has revealed the crucial role of gut microbiota and microbial metabolites in modulating AD. However, the mechanisms by which the microbiome and microbial metabolites affect brain function remain poorly understood. Here, we review the literature on changes in the diversity and composition of the gut microbiome in patients with AD and in animal models of AD. We also discuss the latest progress in understanding the pathways by which the gut microbiota and microbial metabolites from the host or diet regulate AD. By understanding the effects of dietary components on brain function, microbiota composition, and microbial metabolites, we examine the potential for manipulation of the gut microbiota through dietary intervention to delay the progression of AD. Although it is challenging to translate our understanding of microbiome-based approaches to dietary guidelines or clinical therapies, these findings provide an attractive target for promoting brain function.

Novel plant-based meat alternatives: Implications and opportunities for consumer nutrition and health

Against the backdrop of the global protein transition needed to remain within planetary boundaries, there is an influx of plant-based meat alternatives that seek to approximate the texture, flavor and/or nutrient profiles of conventional animal meat. These novel plant-based meat alternatives, enabled by advances in food technology, can be fundamentally different from the whole-plant foods from which they are derived. One of the reasons is the necessity to use food additives on various occasions, since consumers' acceptance of plant-based meat products primarily depends on the organoleptic properties. Consequently, a high degree of heterogeneity in formulation and nutritional profiles exists both within and between product categories of plant-based meat alternatives with unknown effects on several aspects of human health. This is further complicated by the differences in digestibility and bioavailability between proteins from animal and plant sources, which have a profound impact on colonic fermentation, nutritional adequacy and potential health effects. On the other hand, emerging strategies provide opportunities to develop affordable, delicious and nutritious plant-based meat alternatives that align with consumer interests.

Isocaloric Substitution of Plant-Based Protein for Animal-Based Protein and Cardiometabolic Risk Factors in a Multiethnic Asian Population

BACKGROUND

Evidence is accumulating that intake of animal-based and plant-based proteins has different effects on cardiometabolic health, but less is known about the health effect of isocaloric substitution of animal-based and plant-based proteins. Data from Asian populations are limited.

OBJECTIVES

This study aimed to evaluate the effects of isocaloric substitution of total plant-based proteins for total and various animal-based protein food groups and to evaluate the effects of substituting protein from legumes and pulses for various animal-based protein food groups on cardiovascular disease (CVD) risk factors and predicted 10-y CVD risk.

METHODS

We conducted a cross-sectional analysis using data collected from 9211 Singapore residents (aged 21-75 y) from the Singapore Multi-Ethnic Cohort. Data on sociodemographic and lifestyle factors were collected using questionnaires. Dietary intakes were assessed using a validated FFQ. BMI, waist circumference, and blood pressure were measured during a physical examination, and blood samples were collected to measure lipid profiles. Associations were assessed by substitution models using a multiple linear regression analysis.

RESULTS

Isocaloric substitution of total plant-based proteins for total and all specific animal-based protein food groups were associated with lower BMI (β: -0.30; 95% CI: -0.38, -0.22), waist circumference (β: -0.85; 95% CI: -1.04, -0.66), and LDL cholesterol concentrations (β: -0.06; 95% CI: -0.08, -0.05) (P < 0.0056). Replacement of processed meat and processed seafood proteins with total plant-based proteins was associated with improvement in most CVD risk factors and predicted 10-y CVD risk. Replacement of oily fish with legume proteins was associated with lower HDL cholesterol and higher TG concentrations.

CONCLUSIONS

The substitution of plant-based proteins for animal-based proteins, especially from processed meat and processed seafood, was inversely associated with the established CVD risk factors such as BMI, waist circumference, and lipid concentrations and predicted 10-y CVD risk. These findings warrant further investigation in independent studies in other Asian populations.

Dried Fruits, Nuts, and Cancer Risk and Survival: A Review of the Evidence and Future Research Directions

Dried fruits and nuts contain high amounts of nutrients and phytochemicals-all of which may have anticarcinogenic, anti-inflammatory, and antioxidant properties. This narrative review summarizes the evidence for dried fruits and nuts and cancer incidence, mortality, and survival and their potential anticancer properties. The evidence for dried fruits in cancer outcomes is limited, but existing studies have suggested an inverse relationship between total dried fruit consumption and cancer risk. A higher consumption of nuts has been associated with a reduced risk of several site-specific cancers in prospective cohort studies, including cancers of the colon, lung, and pancreas, with relative risks per 5 g/day increment equal to 0.75 (95% CI 0.60, 0.94), 0.97 (95% CI 0.95, 0.98), and 0.94 (95% CI 0.89, 0.99), respectively. A daily intake of total nuts of 28 g/day has also been associated with a 21% reduction in the rate of cancer mortality. There is also some evidence that frequent nut consumption is associated with improved survival outcomes among patients with colorectal, breast, and prostate cancer; however, further studies are needed. Future research directions include the investigation of additional cancer types, including rare types of cancer. For cancer prognosis, additional studies with pre- and postdiagnosis dietary assessment are warranted.

Total and cause-specific mortality associated with meat intake in a large cohort study in Korea

Background

Asia has experienced a large increase in meat intake in the past decade, yet the health impact of meat intake is not well studied.

Objective

We examined the association of meat intake with all-cause, cancer and cardiovascular disease (CVD) mortality in an Asian country.

Methods

Participants were 113,568 adults with dietary data at recruitment (2004–2013) of the Health Examinees-Gem (HEXA-G) study, a prospective cohort study conducted in 8 regions of Korea. Participants were followed until 31 December 2020. Total, red, white, and organ meat intake were computed based on a 106-item questionnaire. Multivariable Cox proportional hazard models were implemented using the lowest quintile of meat intake as the reference category.

Findings

For 1,205,236 person-years, 3,454 deaths were recorded. High intake of processed red meat was positively associated with all-cause mortality [men: hazard ratio (HR) 1.21, 95% confidence interval (95% CI) 1.07–1.37; women: HR 1.32, 95% CI 1.12–1.56]. Increased risk of all-cause mortality (HR 1.21, 95% CI 1.05–1.39) and cancer mortality (HR 1.24, 95% CI 1.03–1.50) was observed in women with high intake of organ meat. Moderate intake of pork belly was associated with reduced risk of all-cause mortality in men (HR 0.76, 95% CI 0.62–0.93) and women (HR 0.83, 95% 0.69–0.98) but high intake was associated with increased risk of CVD mortality in women (HR 1.84, 95% CI 1.20–2.82). Low beef intake decreased the risk of CVD mortality in men (HR 0.58, 95% CI 0.40–0.84), but roasted pork increased cancer mortality in women (HR 1.26, 95% CI 1.05–1.52).

Conclusion

There was increased risk of all-cause mortality associated with intake of processed red meat in men and women, increased risk of all-cause and cancer mortality with intake of organ meat in women, and increased risk of cancer mortality with intake of roasted pork intake in women. High intake of pork belly increased the risk of CVD mortality in women, but moderate intake was inversely associated with mortality from all-causes in both men and women.

Differences in all-cause mortality risk associated with animal and plant dietary protein sources consumption

The relationship between protein intake and mortality is still controversial. We prospectively examined the associations of dietary protein sources with all-cause mortality risk in the Isfahan cohort study (ICS). A total of 5431 participants, aged ≥ 35 years, were enrolled in the ICS, in 2001 and followed through 2013. The frequency of protein intakes from different sources was estimated through a validated food frequency questionnaire at baseline. Any new case of death was recorded over the follow-up duration. Hazard ratio (HR)s and 95% confidence interval (CI)s were estimated through Cox proportional hazards regression models. During a median follow-up of 11.3 years, 483 deaths were documented. Higher intakes of plant proteins (HR = 0.64, 95% CI 0.46, 0.91) and animal proteins (HR = 1.52, 95% CI 1.13, 2.05) were associated with a decreased and increased risk of mortality, respectively. Additional adjustment for some mediators did not considerably affect the associations for animal protein (HR = 1.55, 95% CI 1.15, 2.09), whereas led to a tendency towards lower risk for plant protein in the top quintile compared with the bottom one (HR = 0.67, 95% CI 0.48, 0.95; P trend = 0.06). Among specific major sources, higher intakes of nuts and fish were associated with a 27% (95% CI 0.58, 0.93) and 21% (95% CI 0.62, 1.01) lower risk of mortality, respectively. The inverse association between plant protein and mortality risk might be mediated by some metabolic disorders. However, our results suggest an independent positive association for animal protein and all-cause mortality.

Nuts and seeds consumption and risk of cardiovascular disease, type 2 diabetes and their risk factors: a systematic review and meta-analysis

Objectives

We aimed to systematically review studies and evaluate the strength of the evidence on nuts/seeds consumption and cardiometabolic diseases and their risk factors among adults.

Methods

A protocol was pre-registered in PROSPERO (CRD42021270554). We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials and Scopus up to September 20, 2021 for prospective cohort studies and ≥12-week randomized controlled trials (RCTs). Main outcomes were cardiovascular disease (CVD), coronary heart disease (CHD), stroke and type 2 diabetes (T2D), secondary total-/low density lipoprotein (LDL)-cholesterol, blood pressure and glycaemic markers. Data extraction and risk of bias (RoB) assessments (using RoB 2.0 and RoB-NObS) were performed in duplicate. Effect sizes were pooled using random-effects meta-analyses and expressed as relative risk (RR) or weighted mean differences with 95% confidence intervals (CI); heterogeneity quantified as I ². One-stage dose-response analyses assessed the linear and non-linear associations with CVD, CHD, stroke and T2D. The strength of evidence was classified per the World Cancer Research Fund criteria.

Results

After screening 23,244 references, we included 42 papers from cohort studies (28 unique cohorts, 1,890,573 participants) and 18 RCTs (2,266 participants). In the cohorts, mainly populations with low consumption, high versus low total nuts/seeds consumption was inversely associated with total CVD (RR 0.81; 95% CI 0.75, 0.86; I ² = 67%), CVD mortality (0.77; 0.72, 0.82; I ² = 59.3%), CHD (0.82; 0.76, 0.89; I ² = 64%), CHD mortality (0.75; 0.65, 0.87; I ² = 66.9%) and non-fatal CHD (0.85; 0.75, 0.96; I ² = 62.2%). According to the non-linear dose-response analyses, consumption of 30 g/day of total nuts/seeds was associated with RRs of similar magnitude. For stroke and T2D the summary RR for high versus low intake was 0.91 (95% CI 0.85, 0.97; I ² = 24.8%) and 0.95 (0.75, 1.21; I ² = 82.2%). Intake of nuts (median ~50 g/day) lowered total (-0.15 mmol/L; -0.22, -0.08; I ² = 31.2%) and LDL-cholesterol (-0.13 mmol/L; -0.21, -0.05; I ² = 68.6%), but not blood pressure. Findings on fasting glucose, HbA1c and insulin resistance were conflicting. The results were robust to sensitivity and subgroup analyses. We rated the associations between nuts/seeds and both CVD and CHD as probable. There was limited but suggestive evidence for no association with stroke. No conclusion could be made for T2D.

Conclusion

There is a probable relationship between consumption of nuts/seeds and lower risk of CVD, mostly driven by CHD, possibly in part through effects on blood lipids. More research on stroke and T2D may affect the conclusions. The evidence of specific nuts should be further investigated.

Effect of Iso-Caloric Substitution of Animal Protein for Other Macro Nutrients on Risk of Overall, Cardiovascular and Cancer Mortality: Prospective Evaluation in EPIC-Heidelberg Cohort and Systematic Review

Ecological studies showed correlations between a shift toward animal-protein-rich diets and longer life-expectancy; however, only a few studies examined individual-level association of protein source and mortality risks using appropriate iso-caloric substitution models adjusted for total energy intake. We used EPIC-Heidelberg (European Prospective Investigation into Cancer and nutrition) to create iso-caloric substitution models and determined relative all-cause, cardiovascular and cancer mortality hazards associated with dietary intake of animal protein and other macronutrients, employing Cox proportional hazard models. For comparison with other studies, we also synthesized evidence from a systematic review relating animal protein intake to mortality risk from seven prospective cohort studies in the USA, Europe and Japan. Substitution of 3% of total energy from animal protein for fat (saturated, mono-unsaturated) and carbohydrate (simple, complex) was associated with all-cause mortality (Hazard Ratios [HR] from 1.05 to 1.11), mostly driven by cardiovascular mortality (HR from 1.13 to 1.15). Independently of animal protein, substituting poly-unsaturated fat for saturated fat increased cancer-related mortality risk by 12 percent. The systematic review largely corroborated our findings. Overall, higher proportions of dietary energy from animal protein, combined with low energy intake from either carbohydrate sub-types or dietary fats, increases all-cause and cardiovascular mortality risks, but not cancer-related mortality.

Legume Consumption and Risk of All-Cause and Cause-Specific Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies

There is an equivocal and inconsistent association between legume consumption and health outcomes and longevity. The purpose of this study was to examine and quantify the potential dose-response relationship between legume consumption and all-cause and cause-specific mortality in the general population. We conducted a systematic literature search on PubMed/Medline, Scopus, ISI Web of Science, and Embase from inception to September 2022, as well as reference lists of relevant original papers and key journals. A random-effects model was used to calculate summary HRs and their 95% CIs for the highest and lowest categories, as well as for a 50 g/d increment. We also modeled curvilinear associations using a 1-stage linear mixed-effects meta-analysis. Thirty-two cohorts (31 publications) involving 1,141,793 participants and 93,373 deaths from all causes were included. Higher intakes of legumes, compared with lower intakes, were associated with a reduced risk of mortality from all causes (HR: 0.94; 95% CI: 0.91, 0.98; n = 27) and stroke (HR: 0.91; 95% CI: 0.84, 0.99; n = 5). There was no significant association for CVD mortality (HR: 0.99; 95% CI: 0.91, 1.09; n =11), CHD mortality (HR: 0.93; 95% CI: 0.78, 1.09; n = 5), or cancer mortality (HR: 0.85; 95% CI: 0.72, 1.01; n = 5). In the linear dose-response analysis, a 50 g/d increase in legume intake was associated with a 6% reduction in the risk of all-cause mortality (HR: 0.94; 95% CI: 0.89, 0.99; n = 19), but no significant association was observed for the remaining outcomes. The certainty of evidence was judged from low to moderate. A higher legume intake was associated with lower mortality from all causes and stroke, but no association was observed for CVD, CHD, and cancer mortality. These results support dietary recommendations to increase the consumption of legumes.

Protein-to-carbohydrate ratio is informative of diet quality and associates with all-cause mortality: Findings from the National Health and Nutrition Examination Survey (2007-2014)

Background

Dietary protein and carbohydrate intake and health outcomes have received extensive attention in recent years. However, the nutritional context in which these associations occur is less studied.

Objectives

We aimed to examine the dietary context associating protein-to-carbohydrate ratio and all-cause mortality in US adults.

Methods

Data from 17,814 adults enrolled in the 2007-2014 NHANES was analyzed. Information on mortality was obtained from the US mortality registry updated in December 2015. Diet quality was assessed using the Healthy Eating Index (HEI) and Total Nutrients Index (TNI). ANCOVA was used to test the mean differences in HEI and TNI scores across %E P:C quintiles. Linear regression examined the association of HEI and TNI with %E P:C. Cox proportional hazards regression evaluated the association between %E P:C and all-cause mortality. A restricted cubic spline examined the non-linear relationship between %E P:C and death.

Results

Low %E P:C was associated with lower HEI and TNI scores while higher %E P:C was associated with healthier HEI and TNI scores. HEI and TNI were positively associated with %E P:C (β = 0.22, 95% CI: 0.19-0.25, and β = 0.16, 95% CI: 0.14-0.18), respectively. Low %E P:C was associated with an increased risk of death from all-cause. The higher HRs (95% CIs) of all-cause mortality were 1.97(1.46-2.65), and 7.35 (2.57-21.03) in the second quintile for the age-sex-ethnicity model, and the fully adjusted model, respectively. There was a significant reverse U-shape relationship between %E P:C and all-cause mortality with P, non-linearity < 0.001.

Conclusion

This study indicates that a low %E P:C that gives emphasis to unhealthy foods increases the risk of death. Hence, it would be useful to consider the complete diet associated with protein intake when making dietary recommendations for populations.

Frequency of Egg Intake Associated with Mortality in Chinese Adults: An 8-Year Nationwide Cohort Study

Whether egg consumption plays a beneficial/detrimental role in affecting human health and longevity has been debated for decades. Large-scale cohort evidence from low- and middle-income populations are scarce. In this study, we aimed to assess the association of egg consumption with mortality in Chinese adults. A nationwide cohort of 30,835 participants ages 16-110 years were enrolled from 25 provincial regions in China's mainland. Dietary intake (e.g., egg, meat, vegetable) was assessed by a food-frequency questionnaire. Cox proportional hazards models were used to examine associations between egg consumption and mortality, adjusting for demographic characteristics, dietary factors and health status. Dose-response relationships were investigated using the smoothing function of restricted cubic splines. Several subgroup analyses were performed. A total of 1651 all-cause deaths occurred during a median follow-up of 8.1 years. Egg consumption was associated with lower risks of mortality, with the lowest risk occurring in the group of moderate egg intake (3-6 times/week). Compared with non-consumers, the hazard ratios (95% confidence intervals) for mortality were 0.84 (0.72-0.97) for 3-6 times/week and 0.82 (0.69-0.98) for ≥7 times/week, whereas no significant associations were observed among the lower egg intake group (1-2/week). An approximately inverted J-shaped association was observed in three models, while restricting our analysis in the multivariable model (model 3) did not identify a significant violation for the linear relationship (p for nonlinear = 0.122). There were no statistically significant effect modifications in the subgroup analyses. Egg consumption may be associated with lower risks of mortality in Chinese adults. Our findings found moderate-to-high egg consumption might be beneficial for improving long-term health and longevity.

Retail Purchases of Red and Processed Meat by State in the United States

The specific aim was to characterize retail purchases of red and processed meat and other major protein-rich foods in the U.S. and by state. Supermarket scanner data from grocery stores, supermarkets, and big box stores collected from 2017-2019 (NielsenIQ, New York, NY) was used to characterize retail purchases of red meat, processed meat, and other protein-rich foods in thirty-one states representative of US retail food sales. Red meat, processed meat, poultry, seafood, eggs, other meats, and non-meat foods (beans, nuts, seeds, meat alternatives) by weight accounted for 25.9%, 20.4%, 25.8%, 5.9%, 12.6%, 1.3%, and 10.1%, respectively of total sales in 2017-2019. Mean per capita purchases of red meat by weight was 30.1 g/d, ranging from 45.4 g/d in Mississippi to 21.9 g/d in New York. Mean per capita purchases of processed meat by weight was 23.8 g/d, ranging from 36.6 g/d in Mississippi to 15.2 g/d in California. We observed statistically significant correlations between red and processed meat purchases with cardiovascular mortality and colorectal cancer by state. Per capita retail purchases of red and processed meat appear to reflect a dietary pattern that is not consistent with current national and international dietary recommendations.

Plant-Based and Ketogenic Diets As Diverging Paths to Address Cancer: A Review

Importance

As the incidence of cancer and metabolic disorders, such as obesity, concurrently rise, there has been increasing awareness of the pervasive effect of nutrition. The whole foods plant-based diet (WFPBD) and ketogenic diet (KD) have gained popularity in oncology, and this topic is increasingly permeating clinical dialogue.

Observations

Dietary intake is associated with multiple pathways involved in carcinogenesis and tumor progression. Consumption of a plant-enriched diet is associated with reduced cancer incidence and is recommended by dietary guidelines for cancer prevention. Despite a starkly different nutrient composition, a WFPBD and KD can be associated with weight loss, decreased inflammation, and decreased insulin levels. In addition, a WFPBD is associated with increased fiber, phytochemicals, and butyrate levels and decreased insulin-like growth factor 1 levels, whereas a KD exerts potential anticancer effects by increasing β hydroxybutyrate levels. A KD may be of interest in select, less common settings, such as tumors treated with phosphatidylinositol 3-kinase inhibitors, which induce hyperinsulinemia and hyperglycemia. Completed interventional trials have focused on increasing fruit and vegetable intake or reducing fat intake but have not specifically tested WFPBD or KD for cancer prevention or treatment. Currently available data support plant-based diets as opposed to KD as part of a lifestyle associated with reduced cancer risk. In the postdiagnosis setting, there are currently no rigorously tested approaches that support the recommendation of any diet to treat cancer.

Conclusions and Relevance

The results of this review suggest that the collective evidence supports plant-enriched diets vs KD for the reduction of cancer risk and the improvement of metabolic disorders in survivors. Additional prospective randomized clinical trials are needed to encourage use of dietary modification across the cancer continuum. Rigorous trial designs that adapt classical oncologic end points may identify populations that are likely to benefit from starkly contrasting diets. Current data support prioritization of plant-based diets, and future data could further personalize dietary recommendations in cancer populations.

Dietary protein intake during pregnancy and birth weight among Chinese pregnant women with low intake of protein

Background

Previous studies have yielded inconsistent results on the association between maternal dietary protein intake and birth weight. Moreover, little is known about the effects of dietary protein intake from different sources on fetal growth. This study aimed to investigate the associations of different dietary protein sources (total protein, animal protein, plant protein, and major dietary protein sources) during pregnancy with birth weight and the related adverse birth outcomes.

Methods

7310 women were recruited using a stratified multistage random sampling method at 0–12 months (median: 3; 10–90th percentile: 0–7) after delivery in Shaanxi, China. Maternal diets were gathered by a validated FFQ and other characteristics were collected by a standard questionnaire. Multilevel linear or logistic regression models were used to estimate birth weight changes or ORs (95% CIs) for adverse birth outcomes associated with different dietary protein sources during pregnancy.

Results

The mean percentage of energy from total protein was 11.4% (SD 2.2), with only 27.4% of total protein derived from animal protein. Per 3% increase in energy from total protein, animal protein, and dairy protein was associated with birth weight increases of 19.4 g (95% CI 6.0–32.9), 20.6 g (4.8–36.5), and 18.2 g (4.7–31.7), respectively. Per 3% increase in energy from total protein, animal protein, and dairy protein was also associated with lower risks of low birth weight (LBW) (total protein: OR = 0.78, 95% CI 0.64–0.94; animal protein: 0.79, 0.65–0.96; dairy protein: 0.71, 0.56–0.91), small for gestational age (SGA) (total protein: 0.88, 0.79–0.98; animal protein: 0.87, 0.78–0.97; dairy protein: 0.81, 0.68–0.96), and intrauterine growth retardation (IUGR) (total protein: 0.84, 0.72–0.98; animal protein: 0.86, 0.75–0.98; dairy protein: 0.78, 0.66–0.92). We observed no associations of plant protein and other major dietary protein sources with birth weight and the above birth outcomes. The results did not change when maternal protein was substituted for fat or carbohydrate.

Conclusions

Among Chinese pregnant women with low intake of protein, higher intake of dietary protein, in particular animal protein and dairy protein, is associated with higher birth weight and lower risks of LBW, SGA, and IUGR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-022-00678-0.

Egg and Dietary Cholesterol Intake and Risk of All-Cause, Cardiovascular, and Cancer Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies

Objective

This systematic review and meta-analysis of prospective cohort studies examined the associations between egg and dietary cholesterol intake and the risk of mortality from all causes, including cardiovascular disease (CVD) and cancer.

Methods

We searched PubMed, Scopus, ISI Web of Knowledge, and Google Scholar until April 2021, as well as references to the relevant articles retrieved. Random-effects models were used to calculate summary relative risk (RR) and 95% confidence intervals (CIs) for the highest vs. lowest categories of egg and dietary cholesterol intake. Also, linear and non-linear dose–response analyses were conducted to examine the dose-response relationships.

Results

We included 55 studies, comprising data from 2,772,486 individuals with 228,425, 71,745, and 67,211 cases of all-cause, CVD, and cancer mortality, respectively. Intake of each additional egg per day was associated with a 7% higher risk of all-cause (1.07, 95% CI: 1.02–1.12, I² = 84.8%) and a 13% higher risk of cancer mortality (1.13, 95% CI: 1.06–1.20, I² = 54.2%), but was not associated with CVD mortality (1.00, 95% CI: 0.92–1.09, I² = 81.5%). Non-linear analyses showed increased risks for egg consumption of more than 1.5 and 0.5 eggs/day, respectively. Each 100 mg/day increment in dietary cholesterol intake was associated with a 6% higher risk of all-cause mortality (1.06, 95% CI: 1.03–1.08, I² = 34.5%) and a 6% higher risk of cancer mortality (1.06, 95% CI: 1.05–1.07, I² = 0%), but was not associated with CVD mortality (1.04, 95% CI: 0.99–1.10, I² = 85.9%). Non-linear analyses demonstrated elevated risks of CVD and cancer mortality for intakes more than 450 and 250 mg/day, respectively.

Conclusions and Relevance

High-dietary intake of eggs and cholesterol was associated with all-cause and cancer mortality. Little evidence for elevated risks was seen for intakes below 0.5 egg/day or 250 mg/day of dietary cholesterol. Our findings should be considered with caution because of small risk estimates and moderate between-study heterogeneity.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=252564, PROSPERO, identifier: CRD42021252564.

Associations of dairy, meat, and fish intakes with risk of incident dementia and with cognitive performance: the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD)

Purpose

To investigate if dairy, meat, and fish intakes associate with dementia and cognitive performance.

Methods

We included 2497 dementia-free men from Eastern Finland, aged 42–60 years in 1984–1989 at the baseline examinations. Data on cognitive tests [Mini Mental State Exam (MMSE), trail making test (TMT), verbal fluency test (VFL), selective reminding test (SRT), and Russell’s adaptation of the visual reproduction test (VRT)] at the 4-year re-examinations were available for 482 men and on the ApoE phenotype for 1259 men. Data on dementia events were obtained by linkage to national health registers. Diet was assessed with baseline 4-day food records. Cox regression and analysis of covariance were used for analyses.

Results

During a mean 22-year follow-up, 337 men had a dementia diagnosis. Among the foods, only cheese intake associated with dementia risk (hazard ratio in the highest vs. the lowest quartile = 0.72, 95% confidence interval = 0.52–0.99, P-trend = 0.05). In the cognitive tests, higher non-fermented dairy and milk intakes associated with worse verbal fluency (VFT). Higher processed red meat intake associated with worse verbal (SRT) and visual memory (VRT), whereas higher unprocessed red meat intake associated with better general cognitive functioning (MMSE) and processing speed and executive functioning (TMT). Higher fish intake associated with better verbal memory (SRT). Among APOE-ε4 carriers, especially non-fermented dairy intake associated with higher risk of dementia outcomes, and higher fish intake indicated better cognitive performance.

Conclusion

Although higher intake of some food groups associated with cognitive performance, we found little evidence for associations with dementia risk.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-022-02834-x.

The Isocaloric Substitution of Plant-Based and Animal-Based Protein in Relation to Aging-Related Health Outcomes: A Systematic Review

Plant-based and animal-based protein intake have differential effects on various aging-related health outcomes, but less is known about the health effect of isocaloric substitution of plant-based and animal-based protein. This systematic review summarized current evidence of the isocaloric substitutional effect of plant-based and animal-based protein on aging-related health outcomes. PubMed and Embase databases were searched for epidemiologic observational studies published in English up to 15 March 2021. Studies that included adults ≥18 years old; use of a nutritional substitution model to define isocaloric substitution of plant protein and animal protein; health outcomes covering mortality, aging-related diseases or indices; and reported association estimates with corresponding 95% confidence intervals were included. Nine cohort studies and 3 cross-sectional studies were identified, with a total of 1,450,178 subjects included in this review. Consistent and significant inverse association of substituting plant protein for various animal proteins on all-cause mortality was observed among 4 out of 5 studies with relative risks (RRs) from 0.54 to 0.95 and on cardiovascular disease (CVD) mortality among all 4 studies with RRs from 0.58 to 0.91. Among specific animal proteins, the strongest inverse association on all-cause and CVD mortality was identified when substituting plant protein for red and/or processed meat protein, with the effect mainly limited to bread, cereal, and pasta protein when replacing red meat protein. Isocaloric substitution of plant-based protein for animal-based protein might prevent all-cause and CVD-specific mortality. More studies are needed on this topic, particularly for cancer incidence and other specific aging-related diseases.

Dairy Consumption and Total Cancer and Cancer-Specific Mortality: A Meta-Analysis of Prospective Cohort Studies

The association between dairy consumption and cancer mortality varies among studies and remains unclear. Thus, we conducted a comprehensive meta-analysis of prospective cohort studies to examine the association between dairy consumption and total cancer and cancer-specific mortality. We sought eligible studies in PubMed and Web of Science databases for all publications through March 2021, and pooled RRs and 95% CIs were calculated. We identified 34 prospective cohort studies including 3,171,186 participants and 88,545 deaths. Compared with low milk consumption, high milk consumption was associated with higher cancer mortality in females (RR: 1.10; 95% CI: 1.01, 1.21) and people consuming high/whole-fat milk (fat content ≥3.5%) (RR: 1.17; 95% CI: 1.07, 1.28). Increased risks of cancer-specific mortality were detected for liver (RR: 1.13; 95% CI: 1.02, 1.26), ovarian (RR: 1.32; 95% CI: 1.13, 1.55), and prostate (RR: 1.23; 95% CI: 1.02, 1.48) cancers. Also, females with high consumption of fermented milk had a lower cancer mortality risk (RR: 0.85; 95% CI: 0.77, 0.94). High cheese consumption was not associated with total cancer mortality but rather with higher colorectal cancer mortality (RR: 1.22; 95% CI: 1.02, 1.46). There was no association between butter (RR: 1.06; 95% CI: 0.70, 1.59) or total dairy product consumption (RR: 0.99; 95% CI: 0.95, 1.03) and cancer mortality. Our results imply that high milk consumption, especially high/whole-fat milk, was associated with higher cancer mortality, whereas fermented milk consumption was associated with lower cancer mortality, and this was particularly evident in females. Consequently, further studies are warranted.

Dietary Regulation of Gut-Brain Axis in Alzheimer's Disease: Importance of Microbiota Metabolites

Alzheimer's disease (AD) is a neurodegenerative disease that impacts 45 million people worldwide and is ranked as the 6th top cause of death among all adults by the Centers for Disease Control and Prevention. While genetics is an important risk factor for the development of AD, environment and lifestyle are also contributing risk factors. One such environmental factor is diet, which has emerged as a key influencer of AD development/progression as well as cognition. Diets containing large quantities of saturated/trans-fats, refined carbohydrates, limited intake of fiber, and alcohol are associated with cognitive dysfunction while conversely diets low in saturated/trans-fats (i.e., bad fats), high mono/polyunsaturated fats (i.e., good fats), high in fiber and polyphenols are associated with better cognitive function and memory in both humans and animal models. Mechanistically, this could be the direct consequence of dietary components (lipids, vitamins, polyphenols) on the brain, but other mechanisms are also likely to be important. Diet is considered to be the single greatest factor influencing the intestinal microbiome. Diet robustly influences the types and function of micro-organisms (called microbiota) that reside in the gastrointestinal tract. Availability of different types of nutrients (from the diet) will favor or disfavor the abundance and function of certain groups of microbiota. Microbiota are highly metabolically active and produce many metabolites and other factors that can affect the brain including cognition and the development and clinical progression of AD. This review summarizes data to support a model in which microbiota metabolites influence brain function and AD.

Association of Major Dietary Protein Sources With All-Cause and Cause-Specific Mortality: Prospective Cohort Study

Background

Dietary recommendations regarding protein intake have been focused on the amount of protein. However, such recommendations without considering specific protein sources may be simplistic and insufficient.

Methods and Results

We included 102 521 postmenopausal women enrolled in the Women’s Health Initiative between 1993 and 1998, and followed them through February 2017. During 1 876 205 person‐years of follow‐up, 25 976 deaths occurred. Comparing the highest with the lowest quintile, plant protein intake was inversely associated with all‐cause mortality (hazard ratio [HR], 0.91 [0.86, 0.96]), cardiovascular disease mortality (HR, 0.88 [0.79, 0.97]), and dementia mortality (HR, 0.79 [0.67, 0.94]). Among major protein sources, comparing the highest with the lowest quintile of consumption, processed red meat (HR, 1.06 [1.01, 1.10]) or eggs (HR, 1.14 [1.10, 1.19]) was associated with higher risk of all‐cause mortality. Unprocessed red meat (HR, 1.12 [1.02, 1.23]), eggs (HR, 1.24 [1.14, 1.34]), or dairy products (HR, 1.11 [1.02, 1.22]) was associated with higher risk of cardiovascular disease mortality. Egg consumption was associated with higher risk of cancer mortality (HR, 1.10 [1.02, 1.19]). Processed red meat consumption was associated with higher risk of dementia mortality (HR, 1.20 [1.05, 1.32]), while consumption of poultry (HR, 0.85 [0.75, 0.97]) or eggs (HR, 0.86 [0.75, 0.98]) was associated with lower risk of dementia mortality. In substitution analysis, substituting of animal protein with plant protein was associated with a lower risk of all‐cause mortality, cardiovascular disease mortality, and dementia mortality, and substitution of total red meat, eggs, or dairy products with nuts was associated with a lower risk of all‐cause mortality.

Conclusions

Different dietary protein sources have varying associations with all‐cause mortality, cardiovascular disease mortality, and dementia mortality. Our findings support the need for consideration of protein sources in future dietary guidelines.