New Horizons: Dietary protein, ageing and the Okinawan ratio

Rapid benefits in older age from transition to whole food diet regardless of protein source or fat to carbohydrate ratio: Arandomised control trial

Plant-based diets reduces the risk of chronic conditions. The interaction between protein source and other macronutrients-fat (F) and carbohydrate (C)-has yet to be investigated. The aim was to assess the main and interactive effects of protein-source (plant vs. animal) and F:C (high or low) and the transition from an Australian diet to a whole food diet on various health markers in older individuals. This single-blinded, parallel, randomised experimental trial used a 2 × 2 factorial design to compare pro-vegetarian (70:30 plant to animal) versus omnivorous (50:50 plant to animal) diets at 14% protein and varying fat-to-carbohydrate ratios (high fat ~40% vs. low fat ~30%) over 4 weeks. Study foods were provided, alcohol consumption was discouraged, and dietary intake was determined through food records. Analysis included both RCT and observational data. Changes in appetite, palatability of diets, and dietary intake were assessed. Body composition, muscle strength, function, gut microbiome, and cardiometabolic health parameters were measured. Data from 113 (of the 128 randomised) individuals aged 65-75 years were analysed. Pro-vegetarian diets reduced diastolic blood pressure, total cholesterol and glucose levels. Moreover, the overall sample exhibited increased short-chain fatty acids and FGF21 levels, as well as improvements in body composition, function, and cardio-metabolic parameters irrespective of dietary treatment. Transitioning to a diet rich in fruit, vegetables, fibre, and moderate protein was associated with improved health markers in older age, with added benefits from pro-vegetarian diets. Further research on long-term effects is needed.

Peripheral vascular dysfunction and the aging brain

Aging is the greatest non-modifiable risk factor for most diseases, including cardiovascular diseases (CVD), which remain the leading cause of mortality worldwide. Robust evidence indicates that CVD are a strong determinant for reduced brain health and all-cause dementia with advancing age. CVD are also closely linked with peripheral and cerebral vascular dysfunction, common contributors to the development and progression of all types of dementia, that are largely driven by excessive levels of oxidative stress (e.g., reactive oxygen species [ROS]). Emerging evidence suggests that several fundamental aging mechanisms (e.g., "hallmarks" of aging), including chronic low-grade inflammation, mitochondrial dysfunction, cellular senescence and deregulated nutrient sensing contribute to excessive ROS production and are common to both peripheral and cerebral vascular dysfunction. Therefore, targeting these mechanisms to reduce ROS-related oxidative stress and improve peripheral and/or cerebral vascular function may be a promising strategy to reduce dementia risk with aging. Investigating how certain lifestyle strategies (e.g., aerobic exercise and diet modulation) and/or select pharmacological agents (natural and synthetic) intersect with aging "hallmarks" to promote peripheral and/or cerebral vascular health represent a viable option for reducing dementia risk with aging. Therefore, the primary purpose of this review is to explore mechanistic links among peripheral vascular dysfunction, cerebral vascular dysfunction, and reduced brain health with aging. Such insight and assessments of non-invasive measures of peripheral and cerebral vascular health with aging might provide a new approach for assessing dementia risk in older adults.

The Relationship between Dietary Macronutrient Composition and Telomere Length Among US Adults

The role of dietary macronutrients and energy intake in the aging process has been well-established. However, previous research has mainly focused on the association between leukocyte telomere length (LTL) and individual macronutrients, while the effects of macronutrient composition on LTL remain unclear. This cross-sectional analysis involved 4130 US adults (44.8 ± 17.0 years; 51% female) from the National Health and Nutrition Examination Survey during 1999-2002. A single 24-h dietary recall is used to collect dietary data. The relationship between dietary macronutrient composition and LTL is examined using three-dimensional generalized additive models. After adjustment for age, sex, ethnicity, education, physical activity, BMI, and dietary quality, a three-dimensional association of macronutrient composition with LTL (P = 0.02) is revealed. Diets lower in protein (5-10%), higher in carbohydrates (75%), and lower in fat (15-20%) are associated with the longest LTL corresponding to 7.7 years of slower biological aging. Diets lowest in protein (5%) and carbohydrate (40%), while highest in dietary fat (55%) are associated with the shortest LTL, corresponding to accelerated biological aging of 4.4 years. The associations appeared magnified with higher energy intake. These findings support a complex relationship between dietary macronutrients and biological aging independent of diet quality.

Diet composition, adherence to calorie restriction, and cardiometabolic disease risk modification

Calorie restriction (CR) is a promising approach for attenuating the risk of age-related disease. However, the role of diet composition on adherence to CR and the effects of CR on cardiometabolic markers of healthspan remains unknown. We used the Geometric Framework for Nutrition approach to examine the association between macronutrient composition and CR adherence during the 2-year CALERIE trial. Adult participants without obesity were randomized to a 25% CR intervention or an ad libitum intake control. Correlations of cardiometabolic risk factors with macronutrient composition and standard dietary pattern indices [Alternate Mediterranean Diet Index (aMED), Dietary Inflammatory Index (DII), and Healthy Eating Index (HEI)] were also evaluated by Spearman's correlation at each time point. The mean age was 38.1 ± 7.2 years at baseline and the mean BMI was 25.1 ± 1.7. The study population was 70% female. The CR group, but not the control, consumed a higher percentage reported energy intake from protein and carbohydrate and lower fat at 12 months compared to baseline; comparable results were observed at 24 months. Protein in the background of higher carbohydrate intake was associated with greater adherence at 24 months. There was no correlation between macronutrient composition and cardiometabolic risk factors in the CR group. However, statistically significant correlations were observed for the DII and HEI. These findings suggest that individual self-selected macronutrients have an interactive but not independent role in CR adherence. Additional research is required to examine the impact of varying macronutrient compositions on adherence to CR and resultant modification to cardiometabolic risk factors.

Inverse J-Shaped Relationship of Dietary Carbohydrate Intake with Serum Klotho in NHANES 2007-2016

BACKGROUND

The relationship between dietary carbohydrate intake and serum Klotho levels, an aging biomarker, remains uncertain.

OBJECTIVE

This study aimed to investigate the association between dietary carbohydrate intake and serum Klotho levels among American adults aged 40-79.

METHODS

We analyzed data from 10,669 adults aged 40-79 years who participated in the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2016. Trained interviewers assessed dietary carbohydrate intake using a 24 h dietary recall. Serum Klotho concentrations were measured using commercially available ELISA kits provided by IBL International, Japan, which served as the study outcome. Generalized linear models were used to assess the relationship between the carbohydrate energy percentage and serum Klotho concentration, and restricted cubic spline (RCS) analysis was employed to explore any nonlinear associations.

RESULTS

After adjusting for multiple variables, we observed a nonlinear inverse J-shaped relationship (p for non-linearity < 0.001) between the carbohydrate energy percentage and serum Klotho levels. Specifically, the highest serum Klotho levels were associated with a total carbohydrate energy percentage ranging from 48.92% to 56.20% (third quartile). When the carbohydrate energy percentage was evaluated in quartiles, serum Klotho levels decreased by 5.37% (95% CI: -7.43%, -3.26%), 2.70% (95% CI: -4.51%, -0.86%), and 2.76% (95% CI: -4.86%, -0.62%) in the first quartile (<41.46%), second quartile (41.46% to 48.92%), and fourth quartile (≥56.20%), respectively, compared to the third quartile. This relationship was more pronounced in male, non-obese and non-diabetic participants under 60 years of age.

CONCLUSION

A non-linear inverse J-shaped relationship exists among the general U.S. middle-aged and older population between the carbohydrate energy percentage and serum Klotho levels, with the highest levels observed at 48.92% to 56.20% carbohydrate intake.

Nutrition and Healthy Aging: A Review

PURPOSE OF REVIEW

The review attempts to highlight various dietary approaches for healthy aging; it examines the current evidence regarding the impact of various dietary components on physiological, cognitive, and functional outcomes in older adults. The aim is to promote nutritional awareness to add to what is currently reported in this field that helps for the needful revisions in the policy and in the current national nutrition strategy to incorporate effective public health communication on nutrition and aging.

RECENT FINDINGS

The relationship between diet and healthy aging is becoming increasingly clear with recent studies. Consuming a balanced diet that includes nutrient-rich foods, such as fruits, vegetables, whole grains, lean proteins, and healthy fats, has been linked to a lower risk of chronic diseases and better overall health in older adults. Specific dietary factors that have been found to be beneficial for healthy aging include adherence to a Mediterranean-style diet, Okinawa diet, Dietary Approaches to Stop Hypertension (DASH) diet, and caloric restriction as well as the healthy eating index. Therefore, making dietary changes that promote healthy aging can be an important strategy for maintaining physical and cognitive function and preventing age-related diseases. Adopting a healthy diet in older age can be an effective strategy for maintaining optimal health and function with adequate intake of protein, fiber, vitamin D, and omega-3 fatty acids for better physical function, bone health, muscle strength, cognitive function, and lower risk of chronic diseases and disability.

Intrinsic and environmental basis of aging: A narrative review

Longevity has been a topic of interest since the beginnings of humanity, yet its aetiology and precise mechanisms remain to be elucidated. Aging is currently viewed as a physiological phenomenon characterized by the gradual degeneration of organic physiology and morphology due to the passage of time where both external and internal stimuli intervene. The influence of intrinsic factors, such as progressive telomere shortening, genome instability due to mutation buildup, the direct or indirect actions of age-related genes, and marked changes in epigenetic, metabolic, and mitochondrial patterns constitute a big part of its underlying endogenous mechanisms. On the other hand, several psychosocial and demographic factors, such as diet, physical activity, smoking, and drinking habits, may have an even more significant impact on shaping the aging process. Consequentially, implementing dietary and exercise patterns has been proposed as the most viable alternative strategy for attenuating the most typical degenerative aging changes, thus increasing the likelihood of prolonging lifespan and achieving successful aging.

The effects of macronutrients metabolism on cellular and organismal aging

Evidence supports the notion that metabolic pathways are major regulators of organismal aging, and that metabolic perturbations can extend health- and lifespan. For this reason, dietary interventions and compounds perturbing metabolism are currently explored as anti-aging strategies. A common target for metabolic interventions delaying aging is cellular senescence, a state of stable growth arrest that is accompanied by various structural and functional changes including the activation of a pro-inflammatory secretome. Here, we summarize the current knowledge on the molecular and cellular events associated with carbohydrate, lipid and protein metabolism, and define how macronutrients can regulate induction or prevention of cellular senescence. We discuss how various dietary interventions can achieve prevention of disease and extension of healthy longevity by partially modulating senescence-associated phenotypes. We also emphasize the importance of developing personalized nutritional interventions that take into account the current health and age status of the individual.

Nutritional geometry framework of sleep

AIMS

Sleep is a fundamental physiological function and is essential for all animals. Sleep is affected by diet compositions including protein (P) and carbohydrates (C), but there has not been a systematic investigation on the effect of dietary macronutrient balance on sleep.

MAIN METHODS

We used the nutritional geometry framework (NGF) to explore the interactive effects on sleep of protein (P) and carbohydrates (C) in the model organism Drosophila. Both female and male flies were fed various diets containing seven ratios of protein-to-carbohydrates at different energetic levels for 5 days and sleep was monitored by the Drosophila Activity Monitor (DAM) system.

KEY FINDINGS

Our results showed that the combination of low protein and high carbohydrates (LPHC) prolonged sleep time and sleep quality, with fewer sleep episodes and longer sleep duration. We further found that the effects of macronutrients on sleep mirrored levels of hemolymph glucose and whole-body glycogen. Moreover, transcriptomic analyses revealed that a high-protein, low-carbohydrate (HPLC) diet significantly elevated the gene expression of metabolic pathways when compared to the LPHC diet, with the glycine, serine, and threonine metabolism pathway being most strongly elevated. Further studies confirmed that the contents of glycine, serine, and threonine affected sleep.

SIGNIFICANCE

Our results demonstrate that sleep is affected by the dietary balance of protein and carbohydrates possibly mediated by the change in glucose, glycogen, glycine, serine, and threonine.

Nutritional geometry framework of sucrose taste in Drosophila

Dietary protein (P) and carbohydrate (C) have a major impact on sweet taste sensation. However, it remains unclear whether the balance of P and C influences sweet taste sensitivity. Here, we use the nutritional geometry framework (NGF) to address the interaction of protein and carbohydrates and on sweet taste using Drosophila as a model. Our results reveal that high-protein, low-carbohydrate (HPLC) diets sensitize to sweet taste and low-protein, high-carbohydrate (LPHC) diets desensitize sweet taste in both male and female flies. We further investigate the underlying mechanisms of these two diets' effect on sweet taste using RNA sequencing. When compared to the LPHC diet, the mRNA expression of genes involved in the metabolism of glycine, serine, and threonine is significantly upregulated in the HPLC diet, suggesting these amino acids may mediate sweet taste perception. We further find that sweet sensitization occurs in flies fed with the LPHC diet supplemented with serine and threonine. Our study demonstrates that sucrose taste sensitivity is affected by the balance of dietary protein and carbohydrates possibly through changes in serine and threonine.

Essential Minerals and Metabolic Adaptation of Immune Cells

Modern lifestyles deviated considerably from the ancestral routines towards major shifts in diets and increased sedentarism. The trace elements status of the human body is no longer adequately supported by micronutrient-inferior farmed meats and crop commodities produced by the existing agricultural food systems. This is particular evident in the increased obesogenic adipogenesis and low-grade inflammation that fails to resolve with time. The metabolically restrictive environment of the inflamed tissues drives activation and proliferation of transient and resident populations of immune cells in favor of pro-inflammatory phenotypes, as well as a part of the enhanced autoimmune response. As different stages of the immune activation and resolution depend on the availability of specific minerals to maintain the structural integrity of skin and mucus membranes, activation and migration of immune cells, activation of the complement system, and the release of pro-inflammatory cytokines and chemokines, this review discusses recent advances in our understanding of the contribution of select minerals in optimizing the responses of innate and adaptive immune outcomes. An abbreviated view on the absorption, transport, and delivery of minerals to the body tissues as related to metabolic adaptation is considered.

Targeting the liver in dementia and cognitive impairment: Dietary macronutrients and diabetic therapeutics

Many people living with dementia and cognitive impairment have dysfunctional mitochondrial and insulin-glucose metabolism resembling type 2 diabetes mellitus and old age. Evidence from human trials shows that nutritional interventions and anti-diabetic medicines that target nutrient-sensing pathways overcome these deficits in glucose and energy metabolism and can improve cognition and/or reduce symptoms of dementia. The liver is the main organ that mediates the systemic effects of diets and many diabetic medicines; therefore, it is an intermediate target for such dementia interventions. A challenge is the efficacy of these treatments in older age. Solutions include the targeted hepatic delivery of diabetic medicines using nanotechnologies and titration of macronutrients to optimize hepatic energy metabolism.

Diet Composition, Anthropometrics, and Mortality Risk

While overeating is considered a cause of the obesity epidemic as quantified by body mass index (BMI), the association of diet with a body shape index (ABSI) and hip index (HI), which are transformations of waist and hip circumference that are independent of BMI and which predict mortality risk, is poorly known. We used data from the Atherosclerosis Risk in Communities (ARIC) study of about 15,000 middle-aged adults to investigate associations between macronutrient intake (energy, carbohydrate, protein, and fat, the latter two divided into plant and animal sources, all based on self-reported food frequency) with anthropometric indices (BMI, ABSI, and HI). We also analyzed the association of diet and anthropometrics with death rate during approximately 30 years of follow-up. High intake of energy and animal fat and protein was generally associated with higher ABSI and lower HI at baseline, as well as greater mortality hazard. BMI was also positively linked with animal fat and protein intake. In contrast, higher intake of carbohydrates and plant fat and protein was associated with lower ABSI and BMI, higher HI, and lower mortality hazard. For example, after adjustment for potential confounders, each standard deviation of additional plant fat intake (as a fraction of total energy) was associated with a 5% decrease in mortality rate, while animal fat intake was associated with a 5% mortality increase per standard deviation. The directions of the associations between diet and anthropometrics are consistent with those found between anthropometrics and mortality without reference to diet.

The road ahead of dietary restriction on anti-aging: focusing on personalized nutrition

Dietary restriction (DR), including caloric restriction (CR), intermittent fasting (IF), and restriction of specific food compositions, can delay aging, and the main mechanisms include regulation of nutrient-sensing pathways and gut microbiota. However, the effects of DR regimens on longevity remain controversial, as some studies have demonstrated that IF, rather than CR or diet composition, influences longevity, while other studies have shown that the restricted-carbohydrate or -protein diets, rather than CR, determine health and longevity. Many factors, including DR-related factors (carbohydrate or protein composition, degree and duration of DR), and individual differences (health status, sex, genotype, and age of starting DR), would be used to explain the controversial anti-aging effects of DR, thus highlighting the necessity of precise DR intervention for anti-aging. Personalized DR intervention in humans is challenging because of the lack of accurate aging molecular biomarkers and vast individual variability. Using machine learning to build a predictive model based on the data set of clinical features, gut microbiome and metabolome, may be a good method to achieve precise DR intervention. Therefore, this review analyzed the anti-aging effects of various DR regimens, summarized their mechanisms and influencing factors, and proposed a future research direction for achieving personalized DR regimens for slowing aging.

The Less We Eat, the Longer We Live: Can Caloric Restriction Help Us Become Centenarians?

Striving for longevity is neither a recent human desire nor a novel scientific field. The first article on this topic was published in 1838, when the average human life expectancy was approximately 40 years. Although nowadays people on average live almost as twice as long, we still (and perhaps more than ever) look for new ways to extend our lifespan. During this seemingly endless journey of discovering efficient methods to prolong life, humans were enthusiastic regarding several approaches, one of which is caloric restriction (CR). Where does CR, initially considered universally beneficial for extending both lifespan and health span, stand today? Does a lifelong decrease in food consumption represent one of the secrets of centenarians’ long and healthy life? Do we still believe that if we eat less, we will live longer? This review aims to summarize the current literature on CR as a potential life-prolonging intervention in humans and discusses metabolic pathways that underlie this effect.

The Development of the Davis Food Glycopedia-A Glycan Encyclopedia of Food

The molecular complexity of the carbohydrates consumed by humans has been deceptively oversimplified due to a lack of analytical methods that possess the throughput, sensitivity, and resolution required to provide quantitative structural information. However, such information is becoming an integral part of understanding how specific glycan structures impact health through their interaction with the gut microbiome and host physiology. This work presents a detailed catalogue of the glycans present in complementary foods commonly consumed by toddlers during weaning and foods commonly consumed by American adults. The monosaccharide compositions of over 800 foods from diverse food groups including Fruits, Vegetables, Grain Products, Beans, Peas, Other Legumes, Nuts, Seeds; Sugars, Sweets and Beverages; Animal Products, and more were obtained and used to construct the “Davis Food Glycopedia” (DFG), an open-access database that provides quantitative structural information on the carbohydrates in food. While many foods within the same group possessed similar compositions, hierarchical clustering analysis revealed similarities between different groups as well. Such a Glycopedia can be used to formulate diets rich in specific monosaccharide residues to provide a more targeted modulation of the gut microbiome, thereby opening the door for a new class of prophylactic or therapeutic diets.

Efficacy of Restricting Dietary Protein Intake Combined with Buyang Huanwu Decoction in Treating Diabetic Nephropathy and Its Effect on Patients' Inflammatory Factor Levels

Objective

To study the efficacy of restricting dietary protein intake combined with Buyang Huanwu decoction in treating diabetic nephropathy (DN) and its effect on patients' inflammatory factor levels.

Methods

The medical data of 150 DN patients treated in Wuhan No.1 Hospital (June 2018—May 2021) were retrospectively analyzed. All patients received regular therapy, those who received the intervention of restricting dietary protein intake were included in the control group (n = 75), and on this basis, those treated with Buyang Huanwu decoction were included in the experimental group (n = 75), so as to scientifically evaluate their efficacy and inflammatory factor levels after treatment.

Results

The patients' general information was not statistically different between the two groups (P > 0.05); after treatment, the experimental group gained remarkably higher marked effective rate and total effective rate of treatment than the control group (P < 0.05); the inflammatory factor levels of all patients were obviously better than before (P < 0.05), and the levels of TNF-α, IL-2, IL-8, IL-4, and IL-10 were obviously lower in the experimental group than in the control group (P < 0.05); the levels of fasting blood glucose, 2 h postprandial blood glucose, and glycosylated hemoglobin of all patients were remarkably lower than before (P < 0.05), but with no significant between-group difference (P > 0.05); the renal function indexes of all patients were better than before, and between the two groups, the levels of 24 h microalbuminuria, 24 h urine protein excretion, and serum creatinine were obviously lower and the glomerular filtration rate was significantly higher in the experimental group (P all <0.05), and the patients' traditional Chinese medicine (TCM) symptom scores were remarkably lower in the experimental group (P < 0.05).

Conclusion

Jointly applying Buyang Huanwu decoction on the basis of restricting dietary protein intake can effectively promote the clinical efficacy of DN, which is conducive to adjusting the inflammatory factor levels, promoting the patients' renal function, and alleviating the clinical symptoms.

Total protein, not amino acid composition, differs in plant-based versus omnivorous dietary patterns and determines metabolic health effects in mice

Plant-based dietary patterns are associated with improved cardiometabolic health, but causal dietary components are unclear. Protein has been proposed to play a role, but the importance of protein quantity versus quality remains unknown. We investigated the contributions of total protein amount, amino acid (AA) composition, and plant versus animal source. Analysis of total protein and AA composition of food items and dietary patterns revealed differences between individual food items, but few differences between AA profiles of vegan versus omnivorous dietary patterns. Effects of protein quantity, but not quality, on cardiometabolic health markers were observed in mice using semi-purified diets with crystalline AAs in plant versus animal-based ratios and naturally sourced diets with whole-food ingredients. Our data show relatively little difference in protein quality between plant-based and omnivorous dietary patterns and that reduced total protein intake in plant-based dietary patterns may be a contributor to the benefits of plant-based diets.

Culturally-consistent diet among individuals of Mexican descent at the US-Mexico border is associated with sleep duration and snoring

BACKGROUND

Existing studies show that consuming food consistent with one's culture reduces cardiometabolic risk. However, few studies have assessed whether these dietary choices influence sleep health. Accordingly, this study assessed how Mexican food consumption by individuals of Mexican descent residing at the US-Mexico border, was associated with various measures of sleep, after accounting for acculturation.

METHODS

Data were provided by 100 adults between the ages of 18-60, in the city of Nogales, AZ. Questionnaires were provided in either Spanish or English. Acculturation was assessed with the Acculturation Scale for Mexican-Americans (ARSMA-II), with an additional question, asking how often "my family cooks Mexican foods." Frequency of cooking Mexican food was coded as either "yes" or "no." Sleep was assessed, using validated measures that include the Insomnia Severity Index (ISI), the Epworth Sleepiness Scale (ESS), the Pittsburgh Sleep Quality Index (PSQI), and sleep duration with the item "how many hours of actual sleep did you get at night?" Regression models estimated the associations between sleep health variables as outcomes and consumption of Mexican food as the independent variable. Covariates included age, sex, and acculturation scores. Parental education level was also included, as an indicator of childhood socioeconomic status and since food culture likely involves parents.

RESULT

We found that among individuals who identified as Mexican-Americans who consumed culturally-consistent foods, was associated with, on average, 1.41 more hours of sleep (95% CI 0.19, 2.62; p = 0.024) and were less likely to report snoring (OR: 0.25; 95% CI 0.07, 0.93; p = 0.039). Consuming Mexican food was not associated with sleep quality, insomnia severity or sleepiness.

CONCLUSION

Individuals of Mexican descent residing at the US-Mexico border who regularly consumed Mexican food, reported more sleep and less snoring. Mexican acculturation has been shown previously to improve sleep health. This is likely due to consumption of a culturally- consistent diet. Future studies should examine the role of acculturation in sleep health, dietary choices, and subsequent cardiometabolic risk.

Transcriptomic Effects of Healthspan-Promoting Dietary Interventions: Current Evidence and Future Directions

Aging is the greatest risk factor most diseases, including cardiovascular disorders, cancers, diabetes, and neurodegeneration, but select nutritional interventions may profoundly reduce the risk for these conditions. These interventions include calorie restriction, intermittent fasting, protein restriction, and reducing intake of certain amino acids. Certain ad libitum diets, including the Mediterranean, Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability, and Okinawan diets also promote healthy aging. Evidence indicates that these dietary strategies influence aging and healthspan by acting on the biological "hallmarks of aging" and especially upstream nutrient sensing pathways. Recent advances in "omics" technologies, including RNA-sequencing (transcriptomics), have increased our understanding of how such nutritional interventions may influence gene expression related to these biological mediators of aging, primarily in pre-clinical studies. However, whether these effects are also reflected in the human transcriptome, which may provide insight on other downstream/related cellular processes with aging, is an emerging topic. Broadly, the investigation of how these nutritional interventions influence the transcriptome may provide novel insight into pathways associated with aging, and potential targets to treat age-associated disease and increase healthspan. Therefore, the purpose of this mini review is to summarize what is known about the transcriptomic effects of key dietary/nutritional interventions in both pre-clinical models and humans, address gaps in the literature, and provide insight into future research directions.

Whole-Grain Intake in the Mediterranean Diet and a Low Protein to Carbohydrates Ratio Can Help to Reduce Mortality from Cardiovascular Disease, Slow Down the Progression of Aging, and to Improve Lifespan: A Review

Increase in the aging population is a phenomenon all over the world. Maintaining good functional ability, good mental health, and cognitive function in the absence of severe disease and physical disability define successful aging. A healthy lifestyle in middle age predisposes successful aging. Longevity is the result of a multifactorial phenomenon, which involves feeding. Diets that emphasize fruit and vegetables, whole grains rather than refined grains, low-fat dairy, lean meats, fish, legumes, and nuts are inversely associated with mortality or to a lower risk of becoming frail among elderly subjects. A regular physical activity and a regular intake of whole grain derivatives together with the optimization of the protein/carbohydrate ratio in the diet, where the ratio is significantly less than 1 such as in the Mediterranean diet and the Okinawan diet, reduces the risk of developing aging-related diseases and increases healthy life expectancy. The purpose of our review was to analyze cohort and case-control studies that investigated the effects of cereals in the diet, especially whole grains and derivatives as well as the effects of a diet with a low protein-carbohydrate ratio on the progression of aging, mortality, and lifespan.

Nutritional geometry of female chimpanzees (Pan troglodytes)

Primate foraging is influenced by the spatial and temporal distribution of foods, which may facilitate or constrain optimal nutrient intakes. Chimpanzees are frugivorous primates that mainly subsist on ripe fruit that is typically low in available protein (AP) and high in easily digestible carbohydrates. Because chimpanzees prefer ripe fruit and often eat it in large quantities compared with other foods, we hypothesized that protein intake would be tightly regulated while non-protein energy (NPE) would vary with fruit intake. To test this hypothesis, we conducted all-day follows on female chimpanzees, recorded all types of food consumed (i.e., drupes, figs, and non-fruit foods), estimated the nutritional contributions of these foods to daily NPE and AP intake and investigated how the ratio of NPE to AP varied due to changes in the types of foods consumed. Although the proportions of drupes, figs, and non-fruit foods varied in their diets, female chimpanzees maintained a relatively stable intake of AP while intake of NPE varied depending on the daily diet, demonstrating that like other frugivorous primates studied to date, chimpanzees prioritize protein. The mean daily ratio of NPE to AP was 7:1, which is similar to that of other frugivorous primates studied. Our results support the hypothesis that frugivorous animals may generally prioritize AP, while maximizing NPE intake within that constraint, and could shed light on aspects of human dietary evolution.

Macronutrient Determinants of Obesity, Insulin Resistance and Metabolic Health

Obesity caused by the overconsumption of calories has increased to epidemic proportions. Insulin resistance is often associated with an increased adiposity and is a precipitating factor in the development of cardiovascular disease, type 2 diabetes, and altered metabolic health. Of the various factors contributing to metabolic impairments, nutrition is the major modifiable factor that can be targeted to counter the rising prevalence of obesity and metabolic diseases. However, the macronutrient composition of a nutritionally balanced "healthy diet" are unclear, and so far, no tested dietary intervention has been successful in achieving long-term compliance and reductions in body weight and associated beneficial health outcomes. In the current review, we briefly describe the role of the three major macronutrients, carbohydrates, fats, and proteins, and their role in metabolic health, and provide mechanistic insights. We also discuss how an integrated multi-dimensional approach to nutritional science could help in reconciling apparently conflicting findings.

Impact of Polyphenolic-Food on Longevity: An Elixir of Life. An Overview

Aging and, particularly, the onset of age-related diseases are associated with tissue dysfunction and macromolecular damage, some of which can be attributed to accumulation of oxidative damage. Recently, growing interest has emerged on the beneficial effects of plant-based diets for the prevention of chronic diseases including obesity, diabetes, and cardiovascular disease. Several studies collectively suggests that the intake of polyphenols and their major food sources may exert beneficial effects on improving insulin resistance and related diabetes risk factors, such as inflammation and oxidative stress. They are the most abundant antioxidants in the diet, and their intake has been associated with a reduced aging in humans. Polyphenolic intake has been shown to be effective at ameliorating several age-related phenotypes, including oxidative stress, inflammation, impaired proteostasis, and cellular senescence, both in vitro and in vivo. In this paper, effects of these phytochemicals (either pure forms or polyphenolic-food) are reviewed and summarized according to affected cellular signaling pathways. Finally, the effectiveness of the anti-aging preventive action of nutritional interventions based on diets rich in polyphenolic food, such as the diets of the Blue zones, are discussed.

Nutrition as a Key Modifiable Factor for Periodontitis and Main Chronic Diseases

Nutrition is recognized as an essential component in the prevention of a number of chronic diseases, including periodontal disease. Based on these considerations, a better understanding is required regarding how the diet, and more particularly the intake of macronutrients and micronutrients, could impact the potential relationship between nutrition and periodontal diseases, periodontal diseases and chronic diseases, nutrition and chronic diseases. To overcome this complexity, an up-to-date literature review on the nutriments related to periodontal and chronic diseases was performed. High-sugar, high-saturated fat, low-polyols, low-fiber and low-polyunsaturated-fat intake causes an increased risk of periodontal diseases. This pattern of nutrients is classically found in the Western diet, which is considered as an ‘unhealthy’ diet that causes cardiovascular diseases, diabetes and cancers. Conversely, low-sugar, high-fiber and high-omega-6-to-omega-3 fatty acid ratio intake reduces the risk of periodontal diseases. The Mediterranean, DASH, vegetarian and Okinawa diets that correspond to these nutritional intakes are considered as ‘healthy’ diets, reducing this risk of cardiovascular diseases, diabetes and cancers. The role of micronutrients, such as vitamin D, E, K and magnesium, remains unclear, while others, such as vitamin A, B, C, calcium, zinc and polyphenols have been shown to prevent PDs. Some evidence suggests that probiotics and prebiotics could promote periodontal health. Periodontal and chronic diseases share, with a time delay, nutrition as a risk factor. Thus, any change in periodontal health should be considered as a warning signal to control the dietary quality of patients and thus reduce the risk of developing chronic diseases later on.

Global associations between macronutrient supply and age-specific mortality

Animal experiments have demonstrated that energy intake and the balance of macronutrients determine life span and patterns of age-specific mortality (ASM). Similar effects have also been detected in epidemiological studies in humans. Using global supply data and 1,879 life tables from 103 countries, we test for these effects at a macrolevel: between the nutrient supplies of nations and their patterns of ASM. We find that macronutrient supplies are strong predictors of ASM even after correction for time and economic factors. Globally, signatures of undernutrition are evident in the effects of low supply on life expectancy at birth and high mortality across ages, even as recently as 2016. However, in wealthy countries, the effects of overnutrition are prominent, where high supplies particularly from fats and carbohydrates are predicted to lead to high levels of mortality. Energy supplied at around 3,500 kcal/cap/d minimized mortality across ages. However, we show that the macronutrient composition of energy supply that minimizes mortality varies with age. In early life, 40 to 45% energy from each of fat and carbohydrate and 16% from protein minimizes mortality. In later life, replacing fat with carbohydrates to around 65% of total energy and reducing protein to 11% is associated with the lowest level of mortality. These results, particularly those regarding fats, accord both with experimental data from animals and within-country epidemiological studies on the association between macronutrient intake and risk of age-related chronic diseases.

Towards understanding the evolutionary dynamics of mtDNA

Historically, mtDNA was considered a selectively neutral marker that was useful for estimating the population genetic history of the maternal lineage. Over time there has been an increasing appreciation of mtDNA and mitochondria in maintaining cellular and organismal health. Beyond energy production, mtDNA and mitochondria have critical cellular roles in signalling. Here we briefly review the structure of mtDNA and the role of the mitochondrion in energy production. We then discuss the predictions that can be obtained from quaternary structure modelling and focus on mitochondrial complex I. Complex I is the primary entry point for electrons into the electron transport system is the largest respiratory complex of the chain and produces about 40% of the proton flux used to synthesize ATP. A focus of the review is Drosophila's utility as a model organism to study the selective advantage of specific mutations. However, we note that the incorporation of insights from a multitude of systems is necessary to fully understand the range of roles that mtDNA has in organismal fitness. We speculate that dietary changes can illicit stress responses that influence the selective advantage of specific mtDNA mutations and cause spatial and temporal fluctuations in the frequencies of mutations. We conclude that developing our understanding of the roles mtDNA has in determining organismal fitness will enable increased evolutionary insight and propose we can no longer assume it is evolving as a strictly neutral marker without testing this hypothesis.

Dietary Mitophagy Enhancer: A Strategy for Healthy Brain Aging?

Recently, nutritional interventions have received attention as promising approaches to promote human health during a lifespan. The Mediterranean and Okinawan diets have been associated with longevity and decreasing risk for age-related diseases in contrast to the Western diet. The effect might be due to several antioxidative bioactive compounds highly consumed in both diets, namely, resveratrol, hydroxytyrosol, oleuropein, curcumin, and spermidine. This review aims to address the underlying mechanisms of these compounds to enhance mental fitness throughout life with a focus on brain mitophagy. Mitophagy is the autophagic clearance of dysfunctional, redundant, and aged mitochondria. In aging and neurodegenerative disorders, mitophagy is crucial to preserve the autophagy mechanism of the whole cell, especially during oxidative stress. Growing evidence indicates that curcumin, astaxanthin, resveratrol, hydroxytyrosol, oleuropein, and spermidine might exert protective functions via antioxidative properties and as well the enhanced induction of mitophagy mediators. The compounds seem to upregulate mitophagy and thereby alleviate the clearance of dysfunctional and aged mitochondria as well as mitogenesis. Thus, the Mediterranean or Okinawan diet could represent a feasible nutritional approach to reduce the risk of developing age-related cognitive impairment and corresponding disorders via the stimulation of mitophagy and thereby ensure a balanced redox state of brain cells.

Next Generation Strategies for Geroprotection via mTORC1 Inhibition

Inhibition of mTORC1 (mechanistic Target Of Rapamycin Complex 1) with the pharmaceutical rapamycin prolongs the lifespan and healthspan of model organisms including rodents, with evidence now emerging that rapamycin and its analogs may also have rejuvenative effects in dogs and humans. However, the side effects associated with long-term rapamycin treatment, many of which are due to inhibition of a second mTOR complex, mTORC2, have seemed to preclude the routine use of rapamycin as a therapy for age-related diseases. Here, we discuss recent findings suggesting that strong, chronic inhibition of both mTOR complexes may not be necessary to realize the geroprotective effects of rapamycin. Instead, modestly but specifically inhibiting mTORC1 via a variety of emerging techniques, including intermittent or transient treatment with rapamycin derivatives, or specific dietary regimens, may be sufficient to promote health and longevity with reduced side effects. We will also discuss prospects for the development of new molecules that, by harnessing the detailed molecular understanding of mTORC1 signaling developed over the last decade, will provide new routes to the selective inhibition of mTORC1. We conclude that therapies based on the selective inhibition of mTORC1 may soon permit the safer treatment of diseases of aging.

New insights into the association of mid-childhood macronutrient intake to pubertal development in adolescence using nutritional geometry

Nutritional geometry (NG) is a novel dietary analysis approach that considers nutrient balance, rather than single nutrient effects, on health and behaviour. Through NG, recent animal experiments have found that lifespan and reproduction are differentially altered by dietary macronutrient distribution. Epidemiological research using NG reports similar findings for human ageing. Yet, the relation of macronutrient balance to human reproduction, especially reproductive maturation, remains undefined. We studied the impact of childhood macronutrient intake on pubertal maturation, by applying NG to an Australian longitudinal adolescent dataset. Food records, collected at age 8 years from 142 pre-pubertal children (females, 92; males, 50), were analysed for absolute energy, percentage energy and energy-adjusted residuals from protein, carbohydrate and fat. Pubertal stage change (assessed at 8, 13 and 15 years) was modelled to obtain individual mathematical estimates of pubertal timing and tempo. Timing of menarche was recorded. The association of macronutrients to pubertal timing/tempo was assessed via NG, involving generalised additive models and heat maps to aid interpretation. Results showed lower dietary protein (relative to carbohydrate and fat) in girls consistently predicted earlier pubertal timing and menarche, and was related to faster pubertal tempo (all P < 0·05). No significant associations were identified in boys for both timing and tempo. Results suggest a role of non-protein macronutrients in facilitating female maturation; corroborating feeding and reproductive behaviour patterns observed in earlier NG studies of primates. Application of NG to other adolescent datasets is required to confirm the present findings. Such work would advance understanding of how nutrient balance shapes human development and health.

Cardio-metabolic consequences of dietary carbohydrates: reconciling contradictions using nutritional geometry

Carbohydrates are the major source of dietary energy, but their role in health and disease remains controversial. Recent epidemiological evidence suggests that the increased consumption of carbohydrates is associated with obesity and increased risk of mortality and dietary trials show that carbohydrate restriction leads to weight loss and improved glycaemic status in obese and diabetic subjects. In contrast, the diets of populations with long and healthy lifespans (e.g. traditional Okinawans from Japan) are high in carbohydrate and low in protein, and several clinical and preclinical studies have linked low-carbohydrate-high-protein diets with increased mortality risk. In this paper we attempt to reconcile these contradictory findings by moving beyond traditional single-nutrient analyses to consider the interactions between nutrients on health outcomes. We do so using the Geometric Framework (GF), a nutritional modelling platform that explicitly considers the main and interactive effects of multiple nutrients on phenotypic characteristics. Analysis of human data by GF shows that weight loss and improved cardio-metabolic outcomes under carbohydrate restriction derive at least in part from reduced caloric intake due to the concomitantly increased proportion of protein in the diet. This is because, as in many animals, a specific appetite for protein is a major driver of food intake in humans. Conversely, dilution of protein in the diet leverages excess food intake through compensatory feeding for protein ('protein leverage'). When protein is diluted in the diet by readily digestible carbohydrates and fats, as is the case in modern ultra-processed foods, protein leverage results in excess calorie intake, leading to rising levels of obesity and metabolic disease. However, when protein is diluted in the diet by increased quantities of less readily digestible forms of carbohydrate and fibre, energy balance is maintained and health benefits accrue, especially during middle age and early late-life. We argue that other controversies in carbohydrate research can be resolved using the GF methodology in dietary studies.

Proportions of macronutrients, including specific dietary fats, in prospective anti-Alzheimer's diet

Here we present a novel life-long whole-population study, which enabled us to predict a diet that, in terms of macronutrient proportions, may be prophylactic against Alzheimer's Disease (AD). The method is based on the existence of oscillations in the correlation between historical per capita personal income (PCPI) and age-adjusted death rates (AADR) for AD for each state of the USA in 2005. These oscillations can be explained by changing proportions of macronutrients in the average American diet between 1929 and 2005. We assumed that reducing future correlation of PCPI with AADR will reduce the population's susceptibility to AD. Based on the results of fitting macronutrient availabilities to the variability of Roriginal, using Generalized Additive Models (GAM) analysis, we constructed four "Calculator" equations. The Calculator allowed for prediction of an optimal diet characterized by low correlation of PCPI with AADR (Rpredicted) and minimum energy difference from the historical average macronutrient consumption for each corresponding period of life. We predict that protein consumption should be reduced by half in early middle age and late middle age, whereas in late age it should increase. Our predictions are in line with results on humans and simpler organisms in the context of prolonging life.

[Fasting: the Switch of Life-report on the 18th International Congress of the Medical Association for Fasting and Nutrition (ÄGHE)]

The international congress of the German Medical Association for Fasting and Nutrition (ÄGHE e. V.) was held in cooperation with the Maria Buchinger Foundation for the 18th time in June 2019 in Überlingen at Lake Constance. The congress offers a platform for physicians, fasting therapists, and all interested parties to exchange the latest scientific findings in fasting research. "Fasting: the Switch of Life" was the title of the congress, where well-known national and international fasting researchers spoke about health effects of fasting therapies, the indications and contraindications of fasting, and the latest biological, genetic, and neuroscientific findings related to it, such as protein diets and integrative fasting therapies. The religious and spiritual dimension of fasting were also considered in addition to the health-related aspects. Apart from the lectures and case reports, the aim of the congress was to discuss the current developments and challenges in fasting therapy with the participants.

Protein Leverage: Theoretical Foundations and Ten Points of Clarification

Much attention has been focused on fats and carbohydrates as the nutritional causes of energy overconsumption and obesity. In 2003, a model of intake regulation was proposed in which the third macronutrient, protein, is not only involved but is a primary driver of calorie intake via its interactions with carbohydrates and fats. This model, called protein leverage, posits that the strong regulation of protein intake causes the overconsumption of fats and carbohydrates (hence total energy) on diets with a low proportion of energy from protein and their underconsumption on diets with a high proportion of protein. Protein leverage has since been demonstrated in a range of animal studies and in several studies of human macronutrient regulation, and its potential role in contributing to the obesity epidemic is increasingly attracting discussion. Over recent years, however, several misconceptions about protein leverage have arisen. Our aim in this paper is to briefly outline some key aspects of the underlying theory and clarify 10 points of misunderstanding that have the potential to divert attention from the substantive issues.

Influence of Diets with Varying Essential/Nonessential Amino Acid Ratios on Mouse Lifespan

An adequate intake of essential (EAA) and non-essential amino acids (NEAA) is crucial to preserve cell integrity and whole-body metabolism. EAA introduced with diet may be insufficient to meet the organismal needs, especially under increased physiological requirements or in pathological conditions, and may condition lifespan. We therefore examined the effects of iso-caloric and providing the same nitrogenous content diets, any diet containing different stoichiometric blends of EAA/NEAA, on mouse lifespan. Three groups of just-weaned male Balb/C mice were fed exclusively with special diets with varying EAA/NEAA ratios, ranging from 100%/0% to 0%/100%. Three additional groups of mice were fed with different diets, two based on casein as alimentary proteins, one providing the said protein, one reproducing the amino acidic composition of casein, and the third one, the control group, was fed by a standard laboratory diet. Mouse lifespan was inversely correlated with the percentage of NEAA introduced with each diet. Either limiting EAA, or exceeding NEAA, induced rapid and permanent structural modifications on muscle and adipose tissue, independently of caloric intake. These changes significantly affected food and water intake, body weight, and lifespan. Dietary intake of varying EAA/NEAA ratios induced changes in several organs and profoundly influenced murine lifespan. The balanced content of EAA provided by dietary proteins should be considered as the preferable means for “optimal” nutrition and the elevated or unbalanced intake of NEAA provided by food proteins may negatively affect the health and lifespan of mice.

Biomedical and genetic characteristics of the Ryukyuans: demographic history, diseases and physical and physiological traits

Context: The Ryukyu Islands stretch across a southwestern area of the Japanese Archipelago. Because of their unique geographical and historical backgrounds, Ryukyuans have their own genetic and phenotypic characteristics, which have been disclosed in previous anthropological and biomedical studies. Objective: The history, peopling and biomedical and genetic characteristics of Ryukyuans are reviewed and future research directions are discussed. Conclusion: Morphological and genetic studies have suggested the complex demographic history of Ryukyuans and their relationships with other Asian populations. Knowledge of population formation processes is important to understand the distribution of pathogens. In viral infectious diseases, some strains that may be associated with disease symptoms are specific to Ryukyuans. Dramatic changes in diet have played an important role among Ryukyuans in terms of increases in lifestyle-related diseases and mortality risks. To achieve a better understanding of pathogenic disease factors, further integration of findings regarding the genetic and biomedical characteristics of the Ryukyuans is needed.

The impact of dietary protein intake on longevity and metabolic health

Lifespan and metabolic health are influenced by dietary nutrients. Recent studies show that a reduced protein intake or low-protein/high-carbohydrate diet plays a critical role in longevity/metabolic health. Additionally, specific amino acids (AAs), including methionine or branched-chain AAs (BCAAs), are associated with the regulation of lifespan/ageing and metabolism through multiple mechanisms. Therefore, methionine or BCAAs restriction may lead to the benefits on longevity/metabolic health. Moreover, epidemiological studies show that a high intake of animal protein, particularly red meat, which contains high levels of methionine and BCAAs, may be related to the promotion of age-related diseases. Therefore, a low animal protein diet, particularly a diet low in red meat, may provide health benefits. However, malnutrition, including sarcopenia/frailty due to inadequate protein intake, is harmful to longevity/metabolic health. Therefore, further study is necessary to elucidate the specific restriction levels of individual AAs that are most effective for longevity/metabolic health in humans.

Utilizing Dietary Nutrient Ratios in Nutritional Research: Expanding the Concept of Nutrient Ratios to Macronutrients

We recently showed that using micronutrient ratios in nutritional research might provide more insights into how diet affects metabolism and health outcomes, based on the notion that nutrients, unlike drugs, are not consumed one at a time and do not target a single metabolic pathway. In this paper, we present a concept of macronutrient ratios, including intra- and inter-macronutrient ratios. Macronutrient intakes from food only, from the What We Eat in America website (summarized National Health and Nutrition Examination Survey data) were transposed into Microsoft Excel to generate ratios. Overall, the dietary ratios of macronutrients may be more revealing and useful in epidemiology and in basic nutritional research than focusing on individual protein, fat, and carbohydrate intakes. While macronutrient ratios may be applied to all types of nutritional research, nutritional epidemiology, and, ultimately, dietary guidelines, the methodology required has not been established yet. In the meantime, intra- and inter-macronutrient ratios may serve as a measure of individual and total macronutrient quality.

Adherence of Malaysian Adults' Energy and Macronutrient Intakes to National Recommendations: A Review and Meta-Analysis

The present study examined the best available evidence regarding energy and macronutrient intake during adulthood (age 19 to 59 years) in Malaysia and assessed whether intakes adhere to national recommendations, in order to develop recommendations for dietary improvement based on population consumption patterns. A literature review and meta-analysis evaluated intake based on the following characteristics, using information from food balance sheets, national surveys, and individual studies: (1) levels of intake, (2) proportion of the population whose diets adhere to/exceed/fail to meet Malaysian Recommended Nutrient Intake (RNI) levels, and (3) sources of macronutrients observed in these studies. Food balance data suggested high levels of available energy, animal source protein, vegetable fat, and refined carbohydrates. Twenty studies (five nationwide, 15 individual) indicated that Malaysian adults generally met or exceeded recommendations for fat and protein, but were inconsistent with respect to energy and carbohydrates. Information on dietary sources was limited. Due to methodological limitations, insufficient evidence exists regarding energy and macronutrient intakes of Malaysian adults. Improved dietary assessment methods (including use of biomarkers), better data analysis, and updated food composition data, will provide more reliable information on which to base policy decisions and recommendations for improvement.

Acquired Resilience: An Evolved System of Tissue Protection in Mammals

This review brings together observations on the stress-induced regulation of resilience mechanisms in body tissues. It is argued that the stresses that induce tissue resilience in mammals arise from everyday sources: sunlight, food, lack of food, hypoxia and physical stresses. At low levels, these stresses induce an organised protective response in probably all tissues; and, at some higher level, cause tissue destruction. This pattern of response to stress is well known to toxicologists, who have termed it hormesis. The phenotypes of resilience are diverse and reports of stress-induced resilience are to be found in journals of neuroscience, sports medicine, cancer, healthy ageing, dementia, parkinsonism, ophthalmology and more. This diversity makes the proposing of a general concept of induced resilience a significant task, which this review attempts. We suggest that a system of stress-induced tissue resilience has evolved to enhance the survival of animals. By analogy with acquired immunity, we term this system 'acquired resilience'. Evidence is reviewed that acquired resilience, like acquired immunity, fades with age. This fading is, we suggest, a major component of ageing. Understanding of acquired resilience may, we argue, open pathways for the maintenance of good health in the later decades of human life.

The nutritional geometry of liver disease including non-alcoholic fatty liver disease

Nutrition has a profound effect on chronic liver disease, especially non-alcoholic fatty liver disease (NAFLD). Most observational studies and clinical trials have focussed on the effects of total energy intake, or the intake of individual macronutrients and certain micronutrients, such as vitamin D, on liver disease. Although these studies have shown the importance of nutrition on hepatic outcomes, there is not yet any unifying framework for understanding the relationship between diet and liver disease. The Geometric Framework for Nutrition (GFN) is an innovative model for designing nutritional experiments or interpreting nutritional data that can determine the effects of nutrients and their interactions on animal behaviour and phenotypes. Recently the GFN has provided insights into the relationship between dietary energy and macronutrients on obesity and ageing in mammals including humans. Mouse studies using the GFN have disentangled the effects of macronutrients on fatty liver and the gut microbiome. The GFN is likely to play a significant role in disentangling the effects of nutrients on liver disease, especially NAFLD, in humans.

The Geometric Framework for Nutrition as a tool in precision medicine

Fundamental questions in nutrition include, “What constitutes a nutritionally balanced diet?”, “What are the consequences of failing to achieve diet balance?”, and “How does diet balance change across the lifecourse and with individual circumstances?”. Answering these questions requires coming to grips with the multidimensionality and dynamic nature of nutritional requirements, foods and diets, and the complex relationships between nutrition and health, while at the same time avoiding becoming overwhelmed by complexity. Here we illustrate the use of an integrating framework for taming the complexity of nutrition, the Geometric Framework for Nutrition (GFN), and show how this might be used to untap the full potential for nutrition to provide targeted primary interventions and treatments for the chronic diseases of aging. We first briefly introduce the concepts behind GFN, then provide an example of how GFN has been used to relate nutrition to various behavioural, physiological and health outcomes in a large mouse experiment, and end by suggesting a translational pathway to human health.

Does eating less make you live longer and better? An update on calorie restriction

The complexity of aging is hard to be captured. However, apart from its tissue-specific features, a structural and functional progressive decline of the whole organism that leads to death, often preceded by a phase of chronic morbidity, characterizes the common process of aging. Therefore, the research goal of scientists in the field moved from the search for strategies able to extend longevity to those ensuring healthy aging associated with a longer lifespan referred to as “healthspan”. The aging process is plastic and can be tuned by multiple mechanisms including dietary and genetic interventions. To date, the most robust approach, efficient in warding off the cellular markers of aging, is calorie restriction (CR). Here, after a preliminary presentation of the major debate originated by CR, we concisely overviewed the recent results of CR treatment on humans. We also provided an update on the molecular mechanisms involved by CR and the effects on some of the age-associated cellular markers. We finally reviewed a number of tested CR mimetics and concluded with an evaluation of future applications of such dietary approach.

Calorie restriction in rodents: Caveats to consider

The calorie restriction paradigm has provided one of the most widely used and most useful tools for investigating mechanisms of aging and longevity. By far, rodent models have been employed most often in these endeavors. Over decades of investigation, claims have been made that the paradigm produces the most robust demonstration that aging is malleable. In the current review of the rodent literature, we present arguments that question the robustness of the paradigm to increase lifespan and healthspan. Specifically, there are several questions to consider as follows: (1) At what age does CR no longer produce benefits? (2) Does CR attenuate cognitive decline? (3) Are there negative effects of CR, including effects on bone health, wound healing, and response to infection? (4) How important is schedule of feeding? (5) How long does CR need to be imposed to be effective? (6) How do genotype and gender influence CR? (7) What role does dietary composition play? Consideration of these questions produce many caveats that should guide future investigations to move the field forward.

Dietary protein, aging and nutritional geometry

Nearly a century of research has shown that nutritional interventions can delay aging and age- related diseases in many animal models and possibly humans. The most robust and widely studied intervention is caloric restriction, while protein restriction and restriction of various amino acids (methionine, tryptophan) have also been shown to delay aging. However, there is still debate over whether the major impact on aging is secondary to caloric intake, protein intake or specific amino acids. Nutritional geometry provides new perspectives on the relationship between nutrition and aging by focusing on calories, macronutrients and their interactions across a landscape of diets, and taking into account compensatory feeding in ad libitum-fed experiments. Nutritional geometry is a state-space modelling approach that explores how animals respond to and balance changes in nutrient availability. Such studies in insects and mice have shown that low protein, high carbohydrate diets are associated with longest lifespan in ad libitum fed animals suggesting that the interaction between macronutrients may be as important as their total intake.

Cognitive and behavioral evaluation of nutritional interventions in rodent models of brain aging and dementia

Evaluation of behavior and cognition in rodent models underpins mechanistic and interventional studies of brain aging and neurodegenerative diseases, especially dementia. Commonly used tests include Morris water maze, Barnes maze, object recognition, fear conditioning, radial arm water maze, and Y maze. Each of these tests reflects some aspects of human memory including episodic memory, recognition memory, semantic memory, spatial memory, and emotional memory. Although most interventional studies in rodent models of dementia have focused on pharmacological agents, there are an increasing number of studies that have evaluated nutritional interventions including caloric restriction, intermittent fasting, and manipulation of macronutrients. Dietary interventions have been shown to influence various cognitive and behavioral tests in rodents indicating that nutrition can influence brain aging and possibly neurodegeneration.