Intake of total protein, plant protein and animal protein in relation to blood pressure: a meta-analysis of observational and intervention studies

Impact of Quantity and Type of Dietary Protein on Cardiovascular Disease Risk Factors Using Standard and Network Meta-analyses of Randomized Controlled Trials

CONTEXT

Higher protein diets (HPDs) have shown favorable outcomes on weight maintenance and body-composition management; however, their protective effects against cardiovascular diseases (CVDs) remain uncertain and contentious. Furthermore, it is important to consider the influence of other macronutrients in the diet and type of dietary protein when studying HPDs, because this aspect has been overlooked in previous studies.

OBJECTIVE

We assessed the impacts of quantity and type of dietary protein on CVD risk factors.

DATA SOURCES

A database search was conducted in PubMed, Embase, CINAHL, Web of Science, and Cochrane Library and a total of 100 articles met the eligibility criteria.

DATA EXTRACTION

Extracted data from 100 articles were analyzed using standard meta-analysis, and 41 articles were also analyzed using network meta-analysis.

DATA ANALYSIS

In the standard meta-analysis, an HPD had significant favorable effects on systolic blood pressure (SBP) (mean difference [MD] = -1.51 mmHg; 95% CI: -2.77, -0.25), diastolic blood pressure (DBP) (MD = -1.08 mmHg; 95% CI: -1.81, -0.35), and flow-mediated dilation (MD = 0.78%; 95% CI: 0.09, 1.47) compared with lower protein diets. The further network meta-analysis supported that the high-protein, high-carbohydrate, low-fat diet was the most recommended diet to ensure a maximum decrease in SBP, DBP, total cholesterol (TC), and low-density-lipoprotein cholesterol (LDL-C). In comparison to animal-protein-rich diets, plant-protein-rich diets (PPRs) exhibited a significant favorable effects on improving TC (MD = -0.12 mmol/L; 95% CI: -0.19, -0.05), triglyceride (MD = -0.05 mmol/L; 95% CI: -0.09, -0.01), LDL-C (MD = -0.11 mmol/L; 95% CI: -0.18, -0.04), and high-density-lipoprotein cholesterol (MD = 0.03 mmol/L; 95% CI: 0.02, 0.04) levels.

CONCLUSION

Consumption of HPDs and PPRs supports improvements in vascular health and lipid-lipoprotein profiles, respectively. Furthermore, macronutrient composition should be carefully designed in the dietary approach to maximize the effectiveness of HPDs in improving CVD risk factors.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022369931.

Hemp seed protein and its hydrolysate compared with casein protein consumption in adults with hypertension: a double-blind crossover study

BACKGROUND

The effects of consuming hemp seed protein (HSP) as well as its hydrolysate-derived bioactive peptide (HSP+) on blood pressure (BP) has not, to our knowledge, been investigated in humans.

OBJECTIVES

We aimed to investigate how consumption of HSP and its hydrolysate modulates 24-h systolic (SBP) and diastolic BP (DBP) and plasma biomarkers of BP compared with casein.

METHODS

In a double-blind, randomized, crossover design trial, 35 adults who had mild hypertension with SBP between 130 and 160 mmHg and DBP ≤110 mmHg were recruited. Participants were randomly assigned to varying sequences of 3 6-wk treatments, 50 g casein/d, 50 g HSP/d, or 45 g HSP plus 5 g HSP-derived bioactive peptides/d (HSP+), separated by a 2-wk washout period. Treatment effects were assessed with a linear mixed model with repeated measures.

RESULTS

Compared with casein, after HSP+ consumption, 24-h SBP and 24-h DBP decreased from 135.1 and 80.0 mmHg to 128.1 ± 1.6 (P < 0.0001) and 76.0 ± 1.4 mmHg (P < 0.0001), respectively, whereas these values were 133.5 ± 1.6 and 78.9 ± 1.4 mmHg after HSP consumption (P < 0.0001). There were no differences between the HSP and HSP+ consumption in plasma angiotensin-converting enzyme (ACE) activity, renin, or nitric oxide (NO) concentrations. However, these 2 treatments were able to lower both ACE and renin activities and raise NO concentration in plasma compared with casein.

CONCLUSIONS

These results suggest that hemp protein consumption, as well as in combination with bioactive peptides, may have a role in the dietary management of hypertension. This trial was registered at clinicaltrials.gov as NCT03508895.

Dietary protein and blood pressure: an umbrella review of systematic reviews and evaluation of the evidence

INTRODUCTION

This umbrella review aimed to investigate the evidence of an effect of dietary intake of total protein, animal and plant protein on blood pressure (BP), and hypertension (PROSPERO: CRD42018082395).

METHODS

PubMed, Embase and Cochrane Database were systematically searched for systematic reviews (SRs) of prospective studies with or without meta-analysis published between 05/2007 and 10/2022. The methodological quality and outcome-specific certainty of evidence were assessed by the AMSTAR 2 and NutriGrade tools, followed by an assessment of the overall certainty of evidence. SRs investigating specific protein sources are described in this review, but not included in the assessment of the overall certainty of evidence.

RESULTS

Sixteen SRs were considered eligible for the umbrella review. Ten of the SRs investigated total protein intake, six animal protein, six plant protein and four animal vs. plant protein. The majority of the SRs reported no associations or effects of total, animal and plant protein on BP (all "possible" evidence), whereby the uncertainty regarding the effects on BP was particularly high for plant protein. Two SRs addressing milk-derived protein showed a reduction in BP; in contrast, SRs investigating soy protein found no effect on BP. The outcome-specific certainty of evidence of the SRs was mostly rated as low.

DISCUSSION/CONCLUSION

This umbrella review showed uncertainties whether there are any effects on BP from the intake of total protein, or animal or plant proteins, specifically. Based on data from two SRs with milk protein, it cannot be excluded that certain types of protein could favourably influence BP.

Vegetarian Nutrition in Chronic Kidney Disease

There is rising interest globally with respect to the health implications of vegetarian or plant-based diets. A growing body of evidence has demonstrated that higher consumption of plant-based foods and the nutrients found in vegetarian and plant-based diets are associated with numerous health benefits, including improved blood pressure, glycemic control, lipid levels, body mass index, and acid-base parameters. Furthermore, there has been increasing recognition that vegetarian and plant-based diets may have potential salutary benefits in preventing the development and progression of chronic kidney disease (CKD). While increasing evidence shows that vegetarian and plant-based diets have nephroprotective effects, there remains some degree of uncertainty about their nutritional adequacy and safety in CKD (with respect to protein-energy wasting, hyperkalemia, etc.). In this review, we focus on the potential roles of and existing data on the efficacy/effectiveness and safety of various vegetarian and plant-based diets in CKD, as well as their practical application in CKD management.

An Exploration of Dietary Strategies for Hypertension Management: A Narrative Review

This review aims to clarify the influence of various nutritional approaches in the management of hypertension. An extensive search of databases, namely, PubMed, Cochrane Library, Scopus, and Web of Science, was performed, covering the period from January 2012 to October 2023. We used keywords, such as "hypertension," "nutrition," "nutritional management," "nutrient intake," "dietary strategies," "DASH diet," "Mediterranean diet," and related terms. Hypertension, a grave global health concern, affects more than one billion people worldwide. Lifestyle modifications, including nutritional strategies, are important in non-pharmacological interventions. Dietary patterns, such as the DASH (Dietary Approaches to Stop Hypertension) and Mediterranean diets, which emphasize fruit and vegetable consumption, have demonstrated efficacy in reducing blood pressure. Certain nutrients, such as potassium, calcium, and magnesium, have significant effects on blood pressure. The mechanisms underlying these dietary strategies include vasodilation, improvement in endothelial function, regulation of sodium balance, and mitigation of oxidative stress. However, successful implementation of these strategies can be hindered by various factors, such as adherence challenges, socioeconomic disparities, and cultural preferences. In conclusion, robust evidence supports the effectiveness of nutritional strategies in the management of hypertension. DASH and Mediterranean diets, along with an increased intake of specific nutrients, contribute to blood pressure reduction. Hence, comprehensive lifestyle modifications, with a focus on nutritional changes, are recommended as primary or complementary treatments for hypertension. Addressing the identified barriers could enhance the efficacy and use of these dietary approaches in clinical practice.

Dietary modification for prevention and control of high blood pressure

Hypertension (HT) remains the leading cause of cardiovascular and premature death around the world. Diet is one of the important factors that contributes to the development of HT. We review the current evidence of how different dietary factors may influence blood pressure (BP) and consequent development of HT. There is evidence that BP is positively associated with higher consumption of sodium, alcohol, animal-based protein such as red meat, low-quality carbohydrates such as sugar-sweetened beverages, and saturated fatty acids. On the contrary, other dietary constituents have BP-lowering effects. These include potassium, calcium, magnesium, yogurt, eggs, plant-based proteins such as soy and legumes, mono- and polyunsaturated fatty acids, and high-quality carbohydrates such as whole grain and fruits. Dietary fibre is unrelated to BP lowering, possibly due to the different mechanisms of various types of fibre. The effects of caffeine, hibiscus tea, pomegranate, and sesame on BP are also unclear as evidence is hard to assess due to the varying concentrations and different types of drinks used in studies. Implementing dietary changes such as the Dietary Approaches to Stop Hypertension (DASH diet) or adopting a Mediterranean diet has been shown to reduce and control BP. Although the effect of diet on BP control has been established, the optimal amount of each dietary component and consequent ability to devise a personalized diet for HT prevention and BP control for different populations still require further investigation.

Nutritional and genetic determinants of essential hypertension among adult respondents of the 2013 national nutrition survey, Philippines: a preliminary observational study

Preventive strategies for hypertension and its sequelae require an understanding of their predisposing conditions and recognition of at-risk individuals. Several factors, both genetic and nongenetic, are influential, and likely vary in their effects across ethnicities. This study aimed to identify dietary, lifestyle-related differences and genetic variants associated with hypertension in Filipinos. The study included 147 adult Filipino respondents of the 2013 Philippine National Nutrition Survey living in the National Capital Region. Data on the socio-demographic profile and selected lifestyle factors were obtained via face-to-face interviews. Blood pressure, anthropometric and biochemical indicators of health were determined using standard procedures. Hypertension incidence was determined following American College of Cardiology/American Heart Association guideline. Genotyping utilized the customized Illumina Golden Gate genotyping array, with subsequent allele and genotypic association analytics. Genetic variant effects were adjusted to clinical parameters via logistic regression. Between those with and without hypertension, there was relatively higher intake of dietary protein, fat but not carbohydrates in the latter (P<.05). Of note, other established risk factors for hypertension, such as high lipid levels and fasting blood sugar, were consistently frequently seen among hypertensive respondents. Of the gene markers, 3 SNPs (rs10492602 of APOC [3' UTR], rs12721054 of CYP2C19 [exon] and rs4244285 [intergenic between PCDH17-DIAPH3 locus]) remained significant after multivariable logistic regression. The study highlights that both nutrition and genetic information may contribute to hypertension among Filipinos. This could guide public health initiatives to identify Filipinos susceptible to hypertension and recommend control strategies in lowering its morbidity rate.

Impact of low-protein diet on cardiovascular risk factors and kidney function in diabetic nephropathy: A systematic review and meta-analysis of randomized-controlled trials

AIM

To assess the efficacy of low-protein diets (LPD) on cardiovascular risk factors and kidney function in diabetic nephropathy (DN) based on randomized controlled trials (RCTs).

METHODS

A comprehensive systematic search was undertaken in PubMed/MEDLINE, Web of Science, SCOPUS and Embase databases from inception until January 2022 without using time or language restrictions. RCTs which reported the effects of LPD on cardiovascular risk factors and kidney function in DN were considered.

RESULTS

The results of the present study showed that a LPD significantly reduces urinary urea (WMD: -244.49 g/day, 95 % CI: -418.83, -70.16, P = 0.006) and HbA1c (WMD: -0.20, 95 % CI: -0.39, -0.01, P = 0.036) levels. However, the results did not show neither significant nor beneficial effect on other renal function and cardiovascular risk factors. Furthermore, the results of subgroup analysis showed LPD caused a further decrease in HbA1c during the follow-up period of ≤ 24 weeks, protein intake less than 0.8 g/kg/d and in individuals younger than 50 years. Albuminuria also showed a greater reduction in people under the age of 50 with type 1 diabetes (DMT1) following a LPD.

CONCLUSION

The results of the present study showed that LPD significantly reduces urinary urea and HbA1c.

Sex Differences in Dietary Patterns of Adults and Their Associations with the Double Burden of Malnutrition: A Population-Based National Survey in the Philippines

A dietary pattern transition is a risk factor for the double burden of malnutrition (DBM), but related information is limited. This study aimed to identify sex differences in dietary patterns of adults in a low–middle income country and to examine their association with DBM. A total of 8957 adults (4465 men and 4492 non-pregnant and non-lactating women) who participated in the 2013 Philippine National Nutrition Survey were included in the analysis. Logistic regression models were formulated to investigate the relationship between dietary patterns and DBM. The factor analysis derived seven dietary patterns for males and six patterns for females. Results showed that approximately 30% of Filipino adults suffered from DBM. The rice pattern was associated with lower odds of DBM for males only. The meat and sugar pattern in males and the protein-rich foods, cereal, and sugar pattern in females decreased DBM likelihood. An inverse relationship was observed for the vegetables and corn patterns, wherein females had an increased risk for DBM. Our findings suggest that rice-based and meat-containing patterns could play protective roles in DBM development among adults in the Philippines. Understanding sex-specific dietary patterns can be utilized to guide public health nutrition interventions in the prevention of malnutrition in all its forms.

Association between Protein Intake and the Risk of Hypertension among Chinese Men and Women: A Longitudinal Study

This study aimed to examine the relationship between hypertension risk and protein intake in Chinese individuals. Our analysis included 7007 men and 7752 women from 9 China Health and Nutrition Survey waves (1991−2015). The main outcome was incident hypertension. Dietary intake was recorded using a combination of 3 consecutive 24-h recalls and a household food inventory survey. Energy-adjusted cumulative average intakes were analyzed, and Cox proportional hazards regression models were built. After 143,035 person-years of follow-up, 2586 and 2376 new male and female hypertension cases were identified, respectively. In multivariate-adjusted models with dietary protein intakes included as categorical variables, higher animal protein intake was associated with lower hypertension risk in women (p-trend = 0.01), whereas non-significant in men. Plant protein intake showed a significant positive correlation with hypertension risk, while non-significant for total protein. On a continuous scale, restricted cubic spline curves visually revealed L-, J-, and U-shaped associations between hypertension risk and animal-, plant-, and total-protein intakes, respectively, in both sexes (all p-nonlinearity < 0.0001). Our results suggest a beneficial association between intakes of animal, plant, and total proteins and hypertension risk at lower intake levels, and excessive intake of plant or total protein may increase the hypertension risk in the Chinese population.

The long-term association of different dietary protein sources with metabolic syndrome

Due to scarce epidemiologic data linking dietary protein intakes and metabolic syndrome (MetS), we aim to determine the longitudinal association of different types of dietary protein with the incidence of MetS among Iranians adults. The study was conducted in the framework of the Isfahan Cohort Study (ICS) on 6504 adults, aged ≥ 35 years, and free of MetS at baseline. A validated food frequency questionnaire was used for assessing usual dietary intakes. MetS was defined according to the Joint Scientific Statement. Mixed-effects logistic regression was applied to examine the associations between changes in weekly frequency consumption of protein and MetS status. After a median follow-up of 11.25 years, in multivariate-adjusted model, each additional frequency consumption of total protein intake (OR 0.83; 95% CI 0.81-0.85), animal protein (OR 0.80; 95% CI 0.77-0.83), plant protein (OR 0.70; 95% CI 0.64-0.76), red meat (OR 0.74; 95% CI 0.70-0.78), poultry (OR 0.73; 95% CI 0.68-0.78), egg (OR 0.79; 95% CI 0.72-0.88) and nuts and seeds (OR 0.77; 95% CI 0.71-0.84) was associated with reduced risk of MetS. No significant association was found for processed meat (OR 0.96; 95% CI 0.87-1.01) and legumes and soy (OR 0.96; 95% CI 0.86-1.07) with MetS. Our results suggest an independent inverse association between total protein, animal and plant protein and the risk of MetS. These associations did not differ by sex. Although our results can be considered to be a strategy to reduce MetS risk by dietary guidelines, randomized clinical trials are required to confirm our findings.

Is protein the forgotten ingredient: Effects of higher compared to lower protein diets on cardiometabolic risk factors. A systematic review and meta-analysis of randomised controlled trials

BACKGROUND AND AIMS

Higher protein (HP) diets may lead to lower cardiometabolic risk, compared to lower protein (LP) diets. This systematic review and meta-analysis aims to investigate the effects of HP versus LP diets on cardiometabolic risk factors in adults, using the totality of the current evidence from randomised controlled trials (RCTs).

METHODS

Systematic searches were conducted in electronic databases, up to November 2020. Random effects meta-analyses were conducted to pool the standardised mean differences (SMD) and 95% confidence intervals (CI). The main outcomes were weight loss, body mass index (BMI), waist circumference, fat mass, systolic and diastolic BP, total cholesterol, HDL-and LDL-cholesterol, triacylglycerol, fasting glucose and insulin, and glycated haemoglobin.

RESULTS

Fifty-seven articles reporting on 54 RCTs were included, involving 4344 participants (65% female, mean age: 46 (SD 10) years, mean BMI: 33 (SD 3) kg/m²), with a mean study duration of 18 weeks (range: 4 to 156 weeks). Compared to LP diets (range protein (E%):10-23%), HP diets (range protein (E%): 20-45%) led to more weight loss (SMD -0.13, 95% CI: -0.23, -0.03), greater reductions in fat mass (SMD -0.14, 95% CI: -0.24, -0.04), systolic BP (SMD -0.12, 95% CI: -0.21, -0.02), total cholesterol (SMD -0.11, 95% CI: -0.19, -0.02), triacylglycerol (SMD -0.22, 95% CI: -0.30, -0.14) and insulin (SMD -0.12, 95% CI: -0.22, -0.03). No significant differences were observed for the other outcomes.

CONCLUSIONS

Higher protein diets showed small, but favourable effects on weight loss, fat mass loss, systolic blood pressure, some lipid outcomes and insulin, compared to lower protein diets.

Renal and dietary factors associated with hypertension in a setting of disadvantage in rural India

Using a case-control design, we determined risk factors associated with hypertension in a disadvantaged rural population in southern India. Three hundred adults with hypertension and 300 age- and sex-matched controls were extensively phenotyped. Underweight (29%, body mass index < 18.0 kg m^-2), chronic kidney disease (25%, estimated glomerular filtration rate <60 ml min^-1 1.73 m^-2) and anemia (82%) were highly prevalent. The ratio of sodium to potassium excretion was high (8.2). In multivariable conditional logistic regression of continuous variables dichotomized by their median value, hypertension was independently associated with greater abdominal adiposity as assessed by waist-hip ratio [odds ratio (95% confidence interval), 1.89 (1.21-2.97)], lesser protein intake as assessed by 24 h urea excretion [0.39 (0.24-0.65)], and lesser plasma renin activity [0.54 (0.35-0.84)]. Hypertension tended to be independently associated with lesser serum potassium concentration [0.66 (0.44-1.01), P = 0.06]. Furthermore, those with hypertension reported less frequent intake of vegetables and urinary sodium-potassium ratio correlated positively with serum sodium-potassium ratio (r = 0.18). Hypertension was also independently associated with lesser blood hemoglobin concentration [0.48 (0.26-0.88)]. Blood hemoglobin concentration was positively associated with serum iron (r = 0.41) and ferritin (r = 0.25) concentration and negatively associated with total iron binding capacity (r = -0.17), reflecting iron-deficiency anemia. Our findings indicate potential roles for deficient intake of potassium and protein, and iron-deficiency anemia, in the pathophysiology of hypertension in a setting of disadvantage in rural India. Imbalanced intake of potassium and sodium may be driven partly by deficient intake of vegetables or fruit.

Efficacy of different dietary patterns on lowering of blood pressure level: an umbrella review

BACKGROUND

Many systematic reviews and meta-analyses have assessed the efficacy of dietary patterns on blood pressure (BP) lowering but their findings are largely conflicting.

OBJECTIVE

This umbrella review aims to provide an update on the available evidence for the efficacy of different dietary patterns on BP lowering.

METHODS

PubMed and Scopus databases were searched to identify relevant studies through to June 2020. Systematic reviews with meta-analyses of randomized controlled trials (RCTs) were eligible if they measured the effect of dietary patterns on systolic (SBP) and/or diastolic blood pressure (DBP) levels. The methodological quality of included systematic reviews was assessed by A Measurement Tool to Assess Systematic Review version 2. The efficacy of each dietary pattern was summarized qualitatively. The confidence of the effect estimates for each dietary pattern was graded using the NutriGrade scoring system.

RESULTS

Fifty systematic reviews and meta-analyses of RCTs were eligible for review. Twelve dietary patterns namely the Dietary Approaches to Stop Hypertension (DASH), Mediterranean, Nordic, vegetarian, low-salt, low-carbohydrate, low-fat, high-protein, low glycemic index, portfolio, pulse, and Paleolithic diets were included in this umbrella review. Among these dietary patterns, the DASH diet was associated with the greatest overall reduction in BP with unstandardized mean differences ranging from -3.20 to -7.62 mmHg for SBP and from -2.50 to -4.22 mmHg for DBP. Adherence to Nordic, portfolio, and low-salt diets also significantly decreased SBP and DBP levels. In contrast, evidence for the efficacy of BP lowering using the Mediterranean, vegetarian, Paleolithic, low-carbohydrate, low glycemic index, high-protein, and low-fat diets was inconsistent.

CONCLUSION

Adherence to the DASH, Nordic, and portfolio diets effectively reduced BP. Low-salt diets significantly decreased BP levels in normotensive Afro-Caribbean people and in hypertensive patients of all ethnic origins. This review was registered at PROSPERO as CRD42018104733.

A high-protein meal does not improve blood pressure or vasoactive biomarker responses to acute exercise in humans

Blood pressure (BP) responses to exercise yield prognostic information beyond resting BP. While habitual higher dietary protein intake is associated with reduced resting BP, few studies have assessed the impact of high-protein meals on acute BP and vasoactive biomarker responses to exercise. To test the hypothesis that consuming a higher-protein, lower fat meal (HP; 30 g protein, 17 g fat, 52 g carbohydrate) would attenuate the BP response to exercise and result in a more robust post-exercise hypotensive response compared to a lower-protein, higher-fat meal (LP; 13 g protein, 25 g fat, 54 g carbohydrate), we recruited 31 pre-hypertensive subjects to complete this randomized, double-blind, cross-over acute feeding study. One hundred sixty-five minutes after consuming the test HP or LP meal, subjects exercised on a cycle ergometer at 70% VO₂ max for 30 minutes. Blood pressure was measured prior to the meal and periodically before, during, and after exercise for a 315-minute period. Blood samples were periodically collected to quantify plasma arginine, arginine metabolites (asymmetric dimethylarginine, symmetric dimethylarginine; ADMA, SDMA), endothelin-1, nitrates, and nitrites in a subset of subjects (n = 15) as shown in Supplemental Table S1. Consuming the HP meal did not influence the BP responses to exercise, including the post-exercise return to baseline BP or systolic BP area under the curve. While the HP meal resulted in greater postprandial plasma arginine concentrations, ADMA, SDMA, endothelin-1, nitrates, and nitrites were unaltered. These results suggest that consuming a higher-protein, lower-fat meal does not influence BP or vasoactive biomarker responses to exercise compared to a lower-protein, higher-fat meal.

Association Between Plant and Animal Protein Intake and Overall and Cause-Specific Mortality

IMPORTANCE

Although emphasis has recently been placed on the importance of high-protein diets to overall health, a comprehensive analysis of long-term cause-specific mortality in association with the intake of plant protein and animal protein has not been reported.

OBJECTIVE

To examine the associations between overall mortality and cause-specific mortality and plant protein intake.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study analyzed data from 416 104 men and women in the US National Institutes of Health-AARP Diet and Health Study from 1995 to 2011. Data were analyzed from October 2018 through April 2020.

EXPOSURES

Validated baseline food frequency questionnaire dietary information, including intake of plant protein and animal protein.

MAIN OUTCOMES AND MEASURES

Hazard ratios and 16-year absolute risk differences for overall mortality and cause-specific mortality.

RESULTS

The final analytic cohort included 237 036 men (57%) and 179 068 women. Their overall median (SD) ages were 62.2 (5.4) years for men and 62.0 (5.4) years for women. Based on 6 009 748 person-years of observation, 77 614 deaths (18.7%; 49 297 men and 28 317 women) were analyzed. Adjusting for several important clinical and other risk factors, greater dietary plant protein intake was associated with reduced overall mortality in both sexes (hazard ratio per 1 SD was 0.95 [95% CI, 0.94-0.97] for men and 0.95 [95% CI, 0.93-0.96] for women; adjusted absolute risk difference per 1 SD was -0.36% [95% CI, -0.48% to -0.25%] for men and -0.33% [95% CI, -0.48% to -0.21%] for women; hazard ratio per 10 g/1000 kcal was 0.88 [95% CI, 0.84-0.91] for men and 0.86 [95% CI, 0.82-0.90] for women; adjusted absolute risk difference per 10 g/1000 kcal was -0.95% [95% CI, -1.3% to -0.68%] for men and -0.86% [95% CI, -1.3% to -0.55%] for women; all P < .001). The association between plant protein intake and overall mortality was similar across the subgroups of smoking status, diabetes, fruit consumption, vitamin supplement use, and self-reported health status. Replacement of 3% energy from animal protein with plant protein was inversely associated with overall mortality (risk decreased 10% in both men and women) and cardiovascular disease mortality (11% lower risk in men and 12% lower risk in women). In particular, the lower overall mortality was attributable primarily to substitution of plant protein for egg protein (24% lower risk in men and 21% lower risk in women) and red meat protein (13% lower risk in men and 15% lower risk in women).

CONCLUSIONS AND RELEVANCE

In this large prospective cohort, higher plant protein intake was associated with small reductions in risk of overall and cardiovascular disease mortality. Our findings provide evidence that dietary modification in choice of protein sources may influence health and longevity.

Associations of dietary protein intake with all-cause, cardiovascular disease, and cancer mortality: A systematic review and meta-analysis of cohort studies

BACKGROUND AND AIMS

The relationships between dietary protein intake and risk of all-cause, cardiovascular disease (CVD), and cancer mortality are still unclear. We conducted a systematic review with meta-analysis of cohort studies to summarize the evidence.

METHODS AND RESULTS

We searched PubMed and Web of Science for relevant studies through February 2020. The associations of total, animal, and plant proteins with all-cause, CVD, and cancer mortality were evaluated. Study-specific relative risks (RR) were pooled using the fixed effect model when no significant heterogeneity was detected; otherwise the random effect model was employed. Twelve cohort studies were eligible for the study. Increased total protein showed no clear association with risk of all-cause, CVD, and cancer mortality. In the stratified analysis by protein sources, higher plant protein intake was associated with a reduced risk of all-cause mortality (highest vs lowest intake: RR = 0.92; 95% CI: 0.88, 0.96; each 3% increment of intake: RR = 0.97; 95% CI: 0.94, 0.99), and may be associated with a reduced risk of CVD mortality (highest vs lowest intake: RR = 0.90; 95% CI: 0.80, 1.01; each 3% increment of intake: RR = 0.95; 95% CI: 0.91, 0.99). Moreover, higher intake of animal protein may be associated with an increased risk of CVD mortality (highest vs lowest intake: RR = 1.11; 95% CI: 1.01, 1.22; each 3% increment of intake: RR = 1.02; 95% CI: 0.98, 1.06).

CONCLUSION

This study demonstrates that higher plant protein intake is associated with a reduced risk of all-cause and CVD-related mortality. Persons should be encouraged to increase their plant protein intake to potentially decrease their risk of death.

Identification of High-Risk Pregnancies in a Remote Setting Using Ambulatory Blood Pressure: The MINDI Cohort

Background: Ambulatory blood pressure is a potential tool for early detection of complications during pregnancy, but its utility in impoverished settings has not been assessed. This cross-sectional study aimed to determine whether maternal infections, nutrient deficiencies and inflammation (MINDI) were associated with four measures of maternal blood pressure (BP) and to determine their association with symphysis-fundal-height (SFH). Methods: Environmental and dietary factors, intake of iron and a multiple-nutrient supplement (MNS), markers of inflammation, protein, anemia, folate, vitamins B₁₂, A and D status, and urogenital, skin, oral and intestinal nematode infections were measured in indigenous pregnant Panamanian women. Stepwise multiple linear and logistic regression models explored determinants of systolic and diastolic blood pressure (SBP, DBP), hypotension (SBP < 100 and DBP < 60), mean arterial pressure (MAP), elevated MAP (eMAP), and pulse pressure (PP). Associations of BP with intestinal nematodes and with SFH Z scores (≥16 wk) were also explored. Results: Despite absence of high SBP or DBP, 11.2% of women had eMAP. Furthermore, 24.1% had hypotension. Linear regression showed that hookworm infection was associated with higher SBP (P = 0.049), DBP (P = 0.046), and MAP (P = 0.016), whereas Ascaris was associated with lower DBP (P = 0.018) and MAP (P = 0.028). Trichomonas was also associated with lower SBP (P < 0.0001) and MAP (P = 0.009). The presence of Trichuris (OR: 6.7, 95% CI 1.0-44.5) and folic acid deficiency (OR: 6.9, 95% CI 1.4-33.8) were associated with increased odds of eMAP. The odds of low BP was higher in the presence of Ascaris (OR: 3.63 ± 2.28, P = 0.040), but odds were lowered by MNS (OR: 0.35 ± 0.11, P = 0.001), more intake of animal-source foods/wk (OR: 0.7, 95% CI 0.5-0.9) and by higher concentrations of IL-17 (OR: 0.87 ± 0.05, P = 0.016). Conclusion: MINDI were bi-directionally associated with blood pressure indicators. In this MINDI cohort, infections, nutrients and cytokines both raised, and lowered BP indices. The presence of eMAP identified pregnant women at risk of hypertension whereas low PP was associated with lower SFH. Therefore, MAP and PP may help in detecting women at risk of adverse pregnancy outcomes in settings with limited access to technology.

Legume consumption and risk of hypertension in a prospective cohort of Chinese men and women

Prior data on long-term association between legume consumption and hypertension risk are sparse. We aimed to evaluate whether total legume and subtype intakes prospectively associate with hypertension incidence among 8758 participants (≥30 years) from the China Health and Nutrition Survey 2004-2011. Diet was assessed by interviews combining 3-d 24-h food recalls and household food inventory weighing at each survey round. Incident hypertension was identified by self-reports or blood pressure measurements. We applied multivariable Cox regressions to estimate hazard ratios (HR) with corresponding 95 % CI for hypertension across increasing categories of cumulatively averaged legume intakes. For 35 990 person-years (median 6·0 years apiece), we documented 944 hypertension cases. After covariate adjustment, higher total legume intakes were significantly associated with lower hypertension risks, with HR comparing extreme categories being 0·56 (95 % CI 0·43, 0·71; Ptrend < 0·001). Then we found that intakes of dried legumes (HR 0·53 (95 % CI 0·43, 0·65); Ptrend < 0·001) and fresh legumes (HR 0·67 (95 % CI 0·55, 0·81); Ptrend < 0·001) were both related to decreased hypertension hazards. However, further dried legume classification revealed that negative association with hypertension substantially held for soyabean (HR 0·51 (95 % CI 0·41, 0·62); Ptrend < 0·001) but not non-soyabean intakes. In stratified analyses, the association of interest remained similar within strata by sex, BMI, physical activity, smoking and drinking status; rather, significant heterogeneity showed across age strata (Pinteraction = 0·02). Total legume consumption among the over-65s was related to a more markedly reduced hypertension risk (HR 0·47 (95 % CI 0·30, 0·73); Ptrend < 0·001). Our findings suggest an inverse association of all kinds of legume (except non-soyabean) intakes with hypertension risks.

Formulation of protein–polyphenol particles for applications in food systems

Consumers are demanding healthy nutritious foods rich in protein (both plant and animal) and biologically-active phytochemicals from plants, which can help the body to sustain a stronger immune system and fight against oxidative stress.

Dietary Restrictions and Nutrition in the Prevention and Treatment of Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of death in many developed countries and remains one of the major diseases strongly affected by the diet. Nutrition can affect CVD directly by contributing to the accumulation of vascular plaques and also indirectly by regulating the rate of aging. This review summarizes research on nutrition and CVD incidence based on a multipillar system that includes basic research focused on aging, epidemiological studies, clinical studies, and studies of centenarians. The relevant research linking nutrition and CVD with focus on macronutrients and aging will be highlighted. We will review some of the most relevant studies on nutrition and CVD treatment, also focusing on interventions known to delay aging. We will discuss both everyday dietary compositions, as well as intermittent and periodic fasting interventions with the potential to prevent and treat CVD.

Animal and Plant Protein Sources and Cardiometabolic Health

The sources or types of protein in the diet have long been overlooked regarding their link to cardiometabolic health. The picture is complicated by the fact that animal and plant proteins are consumed along with other nutrients and substances which make up the "protein package" so plant and animal protein come with clear nutrient clusters. This review aimed at deciphering the relation between plant and animal protein and cardiometabolic health by examining different nutritional levels (such as amino acids, protein type, protein foods, protein patterns, and associated overall dietary and nutrient patterns) and varying levels of scientific evidence [basic science, randomized controlled trials (RCTs), observational data]. Plant protein in Western countries is a robust marker of nutrient adequacy of the diet, whereas the contribution of animal protein is highly heterogeneous. Yet recent data from large cohorts have confirmed that total and animal proteins are associated with the risk of cardiovascular disease and diabetes, even when fully adjusting for lifestyle and dietary or nutritional factors. Here again, there is marked variability depending on the type of animal protein. Protein from processed red meat and total red meat on the one hand, and from legumes, nuts, and seeds on the other, are often reported at the extremes of the risk range. RCTs using purified proteins have contributed little to the topic to date, inasmuch as the findings cannot readily be extrapolated to current or near-future diets, but RCTs studying whole protein foods have shown a beneficial effect of pulses. Despite the fact that many of the benefits of plant protein reported in observational or interventional studies may stem from the protein package that they convey and the nutrients that they displace, there are also important indications that protein per se may affect cardiometabolic health via the many amino acids that are present in typically contrasting levels in plant compared with animal proteins.

Protein Quantity and Source, Fasting-Mimicking Diets, and Longevity

Dietary modifications, including caloric restriction, dietary restriction, various intervals of fasting, and even limiting the time when food is consumed can have a pronounced impact on longevity. In addition, dietary modifications are powerful interventions to delay, prevent, or treat many aging-related diseases such as cancer and diabetes. Restricting amino acid and protein intake generally decreases aging-related comorbidities and thereby increases health and longevity. However, chronic dietary interventions are likely not feasible for most people due to low adherence to dietary protocols or resistance to drastic changes to lifestyle, and might even cause detrimental effects, possibly by negatively affecting the immune system and wound healing. The periodic use of low-protein, low-calorie fasting-mimicking diets (FMDs) has the potential to promote health benefits, while minimizing the burden of chronic restriction. Protein restriction and FMDs together have the potential to play an important complementary role in medicine by promoting disease prevention and treatment, and by delaying the aging process at least in part by stimulating stem cell-based regeneration in periods of normal food intake after periodic FMD cycles. The aim of this narrative review is to summarize research on the impact of protein restriction on health and longevity in model organisms and to discuss the implementation of an FMD in mice and in human clinical trials and its effects on biomarkers of healthy aging. Taking into account the importance of sex on aging and diet, we include this information in all discussed studies. Whereas for some model organisms of aging, such as rodents, many studies are available, results are more limited for primates and/or humans.

Plant- and animal-protein diets in relation to sociodemographic drivers, quality, and cost: findings from the Seattle Obesity Study

BACKGROUND

Promoting plant-based proteins is at the forefront of many initiatives in public health nutrition.

OBJECTIVES

The aim of this study was to characterize the sociodemographic drivers of plant-based protein diet consumption, and to study these in relation to diet quality and cost.

METHODS

The Seattle Obesity Study series (SOS I and II) yielded the study sample (n = 1636). Sociodemographic data were obtained by survey self-report. Diet quality and cost came from the Fred Hutchinson Cancer Research Center Food-Frequency Questionnaire linked to retail food prices. The Healthy Eating Index 2010 (HEI-2010) and mean adequacy ratio (MAR) served as measures of diet quality. Linear regressions with robust standard errors examined associations.

RESULTS

Total proteins contributed 16.8% of daily dietary energy. The breakdown by animal and plant proteins was 10.9% and 5.9%, respectively. The sociodemographic factors associated with plant-protein consumption were a positive attitude towards healthy eating and higher education but not income. Plant-protein diets were characterized by severalfold increases in nuts and seeds, soy and legumes, but much less meat, poultry, dairy, solid fats, and added sugars. Higher quartiles of plant-based diets were associated with significantly higher HEI-2010 (β: 13.0 from quartile 1 to quartile 4; 95% CI: 11.8, 14.3) and higher MAR (β: 6.0; 95% CI: 3.5, 8.5) with minimal impact on diet costs (β: 0.35; 95% CI: 0.04, 0.67). In contrast, higher quartiles of animal-protein diets were associated with higher diet costs (β: 1.07; 95% CI: 0.77, 1.36) but lower HEI-2010 (β: -3.2; 95% CI: -4.5, -1.9). Each additional 3% of energy from plant proteins was associated with an 8.4-unit increase in HEI-2010 (95% CI: 7.6, 9.1) and with a 4.1-unit increase in MAR (95% CI: 2.7, 5.5) with a minimal increase in diet cost (β: 0.28; 95% CI: 0.06, 0.50).

CONCLUSION

Plant-based protein diets may be a cost-effective way to improve diet quality at all levels of income. Future research needs to evaluate the quality of plant-based protein in relation to amino acids and health.

Effect of high compared with low dairy intake on blood pressure in overweight middle-aged adults: results of a randomized crossover intervention study

BACKGROUND

Observational studies suggest that high dairy intake is associated with a lower blood pressure (BP).

OBJECTIVE

We aimed to investigate the effect of a high-dairy diet (HDD) as compared with a low-dairy diet (LDD) on BP in overweight middle-aged adults.

METHODS

Fifty-two overweight men and women were included in a randomized crossover intervention study. Each subject consumed 2 isocaloric diets for 6 wk, an LDD (≤1 dairy portion per day) and an HDD (6 or 5 reduced-fat dairy portions for men and women, respectively), with a 4-wk washout period in between the diets during which the subjects consumed their habitual diet. BP was measured at the start and at the end of the intervention diets. The effect of the intervention study was evaluated by 2-sample t tests. Mixed-model analyses were used for adjustment for the potential influence of changes in dietary protein and mineral intake and risk factors for hypertension including body weight and plasma cholesterol.

RESULTS

Consumption of an HDD as compared with an LDD resulted in a reduction of both systolic BP (mean ± SD: 4.6 ± 11.2 mm Hg, P < 0.01) and diastolic BP (3.0 ± 6.7 mm Hg, P < 0.01). In further analyses, these reductions appeared dependent on the concomitant increase in calcium intake.

CONCLUSIONS

This intervention study shows that an HDD results in a reduction of both systolic and diastolic BP in overweight middle-aged men and women. If the results of our study are reproduced by other studies, advice for high dairy intake may be added to treatment and prevention of high BP. This trial was registered at trialregister.nl as NTR4899.

Intake of Different Dietary Proteins and Risk of Heart Failure in Men: The Kuopio Ischaemic Heart Disease Risk Factor Study

Supplemental Digital Content is available in the text.

Background:

Animal and plant protein intakes have indicated opposite associations with cardiovascular mortality risk. Whether dietary proteins are associated with risk of heart failure (HF) is unclear. Thus, we examined the associations of proteins from different food sources with risk of HF.

Methods and Results:

The study included 2441 men aged 42 to 60 years at the baseline examinations in 1984 to 1989 in the Kuopio Ischaemic Heart Disease Risk Factor Study. Protein intakes at baseline were assessed with 4-day dietary records. Data on incident HF cases were obtained from national registers. HF risk according to protein intake was estimated by Cox proportional hazard ratios. During the mean follow-up of 22.2 years, 334 incident HF cases occurred. Higher intake of total protein indicated a trend toward increased risk of HF (multivariable-adjusted hazard ratio in the highest versus lowest quartile=1.33; 95% confidence interval: 0.95–1.85; P-trend=0.05). The associations between specific types and sources of protein with incident HF were consistent with this overall finding although not all associations reached statistical significance. For example, the hazard ratio in the highest versus lowest quartile was 1.43 (95% confidence interval: 1.00–2.03; P-trend=0.07) for total animal protein and 1.17 (95% confidence interval: 0.72–1.91; P-trend=0.35) for total plant protein.

Conclusions:

In middle-aged men, higher protein intake was marginally associated with increased risk of HF.

CLINICAL TRIAL REGISTRATION:

URL: https://www.clinicaltrials.gov. Unique identifier: NCT03221127

Modified ketogenic diets in adults with refractory epilepsy: Efficacious improvements in seizure frequency, seizure severity, and quality of life

OBJECTIVE

This study evaluates the efficacy of a modified ketogenic diet (MKD) on seizure frequency, severity, and quality of life (QOL), as well as potential complications of MKD therapy among adults with drug-resistant epilepsy (DRE).

METHODS

Changes in seizure frequency, severity, QOL, and side effects were retrospectively examined among adults, ≥17 years of age, with DRE (≥2 antiepileptic drugs [AEDs]), after 3 months of MKD therapy. Attention was paid to medication or vagus nerve stimulator (VNS) changes as well to evaluate potential confounders.

RESULTS

A total of 60% (n = 33) of the 55 individuals reported ≥50% seizure frequency improvement, 42 (76%) reported improvement in seizure severity, and 48 (87%) reported improvement in QOL. More patients following a modified ketogenic diet - 15 g net carbohydrate daily (MKD-15) (95%) compared with a MKD-50 (69%) reported improvement in QOL (p = 0.02). Weight among the entire sample declined from 77.5 (20) kg to 73.9 (19.0) kg (p < 0.0001), and total cholesterol (TC), low density lipoprotein (LDL), and total cholesterol:high density lipoprotein (TC:HDL) increased significantly (p = 0.03, p = 0.04, and p = 0.02, respectively). Free carnitine values were available for a select number of patients, 26 (47%) at baseline, and 7 (13%) at follow-up, of which 8 (31%) at baseline, and 2 (29%) at follow-up had carnitine deficiency (<25 nmol/mL). Constipation was noted in 5 patients (9%), and no kidney stones were reported during the study period. There were no statistical differences in number or dose changes for AED or VNS during the study period.

SIGNIFICANCE

Modified ketogenic diet therapies reduce seizure frequency and severity and improve QOL among adults with DRE with few side effects outside of weight loss, a desired outcome among many adults with DRE. More restrictive MKDs may offer improved seizure severity and QOL. Modified ketogenic diet therapy increases LDL cholesterol, which may be cardioprotective if related to an increase in LDL particle size with high saturated fat intake; however, more research is needed examining LDL particle size changes among those receiving MKD therapy.

James Lind Alliance research priorities: what role do carbohydrates, fats and proteins have in the management of Type 2 diabetes, and are there risks and benefits associated with particular approaches?

AIMS

To assess the role played by carbohydrates, fat and proteins in the management of Type 2 diabetes.

BACKGROUND

Diabetes research tends to reflect the interests of academics or the pharmaceutical industry, rather than those of people living with Type 2 diabetes. The James Lind Alliance and Diabetes UK addressed this issue by defining the research priorities of people living with Type 2 diabetes. Three of the top 10 research priority questions focused on lifestyle.

METHODS

A narrative review was undertaken with a structured search strategy using three databases. Search terms included the three macronutrients and Type 2 diabetes. No restrictions were placed on macronutrient quantity or length of study follow-up. Outcomes included changes in HbA_1c , body weight, insulin sensitivity and cardiovascular risk.

RESULTS

There is no strong evidence that there is an optimal ratio of macronutrients for improving glycaemic control or reducing cardiovascular risk. Challenges included defining the independent effect of macronutrient manipulation and identifying the effects of macronutrients, independent of foods and dietary patterns. Extreme intakes of macronutrients may be associated with health risks.

CONCLUSIONS

It is challenging to formulate food-based guidelines from studies based on macronutrient manipulation. Structured education should be offered to support individuals in discovering their optimal, individual dietary approach. Recommendations for dietary guidelines should be expressed in terms of foods and not macronutrients.

Vegetable Protein Intake was Inversely Associated with Cardiovascular Mortality in a 15-Year Follow-Up Study of the General Japanese Population

AIM

To examine the relationship between the intake of dietary vegetable protein and CVD mortality in a 15-year follow-up study of a representative sample of the Japanese population.

METHODS

A total of 7,744 participants aged 30 years or older (3,224 males and 4,520 females) who were free of CVD at baseline were included in this analysis. Vegetable protein intake (% energy) was assessed using a three-day semi-weighed dietary record at baseline. Multivariable-adjusted hazard ratios (HRs) were calculated using Cox's proportional hazards model after adjusting for confounding factors.

RESULTS

The total person-years studied were 107,988 with a mean follow-up period of 13.9 years. There were 1,213 deaths during the follow-up period, among which 354 (29.2%) were due to CVD. Vegetable protein intake was associated inversely with CVD and cerebral hemorrhage mortality, with the HRs for a 1% energy increment in vegetable protein intake being 0.86 (95% CI, 0.75-0.99) and 0.58 (95% CI, 0.35-0.95), respectively. In the subgroup analysis of participants with or without hypertension, the inverse association between vegetable protein intake and CVD mortality was more evident in the nonhypertensive group, with the HRs for CVD and stroke being 0.68 (95% CI, 0.50-0.94) and 0.50 (95% CI, 0.30-0.84), respectively.

CONCLUSIONS

Vegetable protein intake may prevent future CVD, particularly in nonhypertensive subjects in the Japanese population. However, further studies are necessary to examine the biological mechanisms of this effect.

Impact of a high-protein diet during lactation on milk composition and offspring in a pig model

PURPOSE

Early postnatal nutrition not only holds relevance to infant growth, but also determines the risk of developing obesity and chronic diseases such as diabetes type 2 and cardiovascular diseases in adulthood. It is suggested that a high-protein (HP) diet in early childhood can predispose children to obesity. However, data concerning possible alterations in milk composition and the development of the offspring in response to a maternal HP diet are currently not available. To address this question, we conducted a study using pigs as a model organism.

METHODS

At parturition, sows were assigned to two experimental groups. During lactation, the control group received a diet with a protein content of 16%, whereas the diet of the HP group contained 30% protein. After 28 days of lactation, samples were taken from sows and piglets for the quantification of free amino acids and other metabolites and for histology.

RESULTS

Serum and milk urea showed the most marked differences between the two groups of sows, whereas serum urea concentration in piglets did not differ. Here, we found that the intake of an HP diet changed a series of metabolites in sows, but had only small effects on milk composition and virtually no effects on growth in the offspring. Interestingly, maternal protein intake during lactation shapes the microbiome of the offspring.

CONCLUSION

From our current study, we conclude that even a very high maternal protein intake throughout lactation has no impact on growth and health parameters of the offspring.

A Comparison of a Pulse-Based Diet and the Therapeutic Lifestyle Changes Diet in Combination with Exercise and Health Counselling on the Cardio-Metabolic Risk Profile in Women with Polycystic Ovary Syndrome: A Randomized Controlled Trial

We compared the effects of a low-glycemic index pulse-based diet, containing lentils, beans, split peas, and chickpeas, to the Therapeutic Lifestyle Changes (TLC) diet on cardio-metabolic measures in women with polycystic ovary syndrome (PCOS). Ninety-five women (18⁻35 years) enrolled in a 16-week intervention; 30 women in the pulse-based and 31 in the TLC groups completed the study. Women participated in aerobic exercise training (minimum 5 days/week for 45 min/day) and were counselled (monthly) about PCOS and lifestyle modification. Women underwent longitudinal follow-up post-intervention. The pulse-based group had a greater reduction in total area under the curve for insulin response to a 75-g oral glucose tolerance test (mean change ± SD: -121.0 ± 229.9 vs. -27.4 ± 110.2 µIU/mL × min; p = 0.05); diastolic blood pressure (-3.6 ± 6.7 vs. -0.2 ± 6.7 mmHg, p = 0.05); triglyceride (-0.2 ± 0.6 vs. 0.0 ± 0.5 mmol/L, p = 0.04); low-density lipoprotein cholesterol (-0.2 ± 0.4 vs. -0.1 ± 0.4 mmol/L, p = 0.05); total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C; -0.4 ± 0.4 vs. 0.1 ± 0.4, p < 0.001); and a greater increase in HDL-C (0.1 ± 0.2 vs. -0.1 ± 0.2 mmol/L, p < 0.01) than the TLC group. Decreased TC/HDL-C (p = 0.02) at six-month and increased HDL-C and decreased TC/HDL-C (p ≤ 0.02) at 12-month post-intervention were maintained in the pulse-based group. A pulse-based diet may be more effective than the TLC diet at improving cardio-metabolic disease risk factors in women with PCOS.

TRIAL REGISTRATION

CinicalTrials.gov identifier, NCT01288638.

Relative Protein Intake and Physical Function in Older Adults: A Systematic Review and Meta-Analysis of Observational Studies

(1) Background: The present work aims to conduct a systematic review and meta-analysis of observational studies, in order to investigate the association of relative protein intake and physical function in older adults; (2) Methods: Observational studies, that investigated the association between protein intake and physical function in older adults, were retrieved from MEDLINE, SCOPUS, CINAHL, AgeLine, EMBASE, and Cochrane-CENTRAL. Two independent researchers conducted study selection and data extraction; (3) Results: Very high protein intake (≥1.2 g/kg/day) and high protein intake (≥1.0 g/kg/day) groups showed better lower limb physical functioning and walking speed (WS) performance, respectively, in comparison to individuals who present relative low protein (<0.80 g/kg/day) intake. On the other hand, relative high protein intake does not seem to propitiate a better performance on isometric handgrip (IHG) and chair rise in comparison to relative low protein intake. In addition, there were no significant differences in the physical functioning of high and middle protein intake groups; (4) Conclusions: In conclusion, findings of the present study indicate that a very high (≥1.2 g/kg/day) and high protein intake (≥1.0 g/kg/day) are associated with better lower-limb physical performance, when compared to low protein (<0.80 g/kg/day) intake, in community-dwelling older adults. These findings act as additional evidence regarding the potential need to increase protein guidelines to above the current recommendations. However, large randomized clinical trials are needed to confirm the addictive effects of high-protein diets (≥1.0 g/kg/day) in comparison to the current recommendations on physical functioning. All data are available in the Open ScienceFramework.

Dietary protein and changes in markers of cardiometabolic health across 20 years of follow-up in middle-aged Americans

OBJECTIVE

Dietary protein plays a role in counteracting age-related muscle loss. However, limited long-term data exist on protein intake and markers of cardiometabolic health, which tend to deteriorate with age.

DESIGN

Prospective cohort study. FFQ-derived protein intake (g/d) and cardiometabolic markers were assessed up to five times across 20 years. Markers included systolic (SBP) and diastolic (DBP) blood pressures, circulating lipids (total, HDL and LDL cholesterol; TAG), estimated glomerular filtration rate (eGFR), fasting glucose (FG), weight and waist circumference (WC). Mixed models accounting for repeated measures were used to estimate adjusted mean annualized changes in outcomes per quartile category of protein.

SETTING

Framingham Heart Study Offspring cohort, USA.

SUBJECTS

Participants (n 3066) with 12 333 unique observations, baseline (mean (sd)) age=54·0 (9·7) years, BMI=27·4 (4·9) kg/m2, 53·5 % female.

RESULTS

In fully adjusted models, there were favourable associations (mean (se)) of total protein with annualized changes in SBP (lowest v. highest intake: 0·34 (0·06) v. 0·04 (0·06) mmHg, P trend=0·001) and eGFR (-1·03 (0·06) v. -0·87 (0·05) ml/min per 1·73 m2, P trend=0·046), unfavourable associations with changes in FG (0·013 (0·004) v. 0·028 (0·004) mmol/l, P trend=0·004) and no associations with weight, WC, DBP or lipids. Animal protein was favourably associated with SBP and unfavourably with FG and WC; plant protein was favourably associated with FG and WC.

CONCLUSIONS

The present study provides evidence that protein intake may influence changes in cardiometabolic health independent of change in weight in healthy adults and that protein's role in cardiometabolic health may depend on the protein source.

A Systematic Review of Renal Health in Healthy Individuals Associated with Protein Intake above the US Recommended Daily Allowance in Randomized Controlled Trials and Observational Studies

A systematic review was used to identify randomized controlled trials (RCTs) and observational epidemiologic studies (OBSs) that examined protein intake consistent with either the US RDA (0.8 g/kg or 10-15% of energy) or a higher protein intake (≥20% but <35% of energy or ≥10% higher than a comparison intake) and reported measures of kidney function. Studies (n = 26) of healthy, free-living adults (>18 y old) with or without metabolic disease risk factors were included. Studies of subjects with overt disease, such as chronic kidney, end-stage renal disease, cancer, or organ transplant, were excluded. The most commonly reported variable was glomerular filtration rate (GFR), with 13 RCTs comparing GFRs obtained with normal and higher protein intakes. Most (n = 8), but not all (n = 5), RCTs reported significantly higher GFRs in response to increased protein intake, and all rates were consistent with normal kidney function in healthy adults. The evidence from the current review is limited and inconsistent with regard to the role of protein intake and the risk of kidney stones. Increased protein intake had little or no effect on blood markers of kidney function. Evidence reported here suggests that protein intake above the US RDA has no adverse effect on blood pressure. All included studies were of moderate to high risk of bias and, with the exception of 2 included cohorts, were limited in duration (i.e. <6 mo). Data in the current review are insufficient to determine if increased protein intake from a particular source, i.e., plant or animal, influences kidney health outcomes. These data further indicate that, at least in the short term, higher protein intake within the range of recommended intakes for protein is consistent with normal kidney function in healthy individuals.

Animal Proteins as Important Contributors to a Healthy Human Diet

Adequate protein intake is critical for health and development. Generally, protein of animal origin is of higher quality for humans owing to its amino acid pattern and good digestibility. When administered in mixtures it can enhance the quality of plant proteins, but its availability is often low in low-income communities, especially in young children, the elderly, and pregnant and lactating women, who have increased requirements and in whom high-quality protein also stimulates (bone) growth and maintenance. Although high protein intake was associated with increased type 2 diabetes mellitus risk, milk and seafood are good sources of branched chain amino acids and taurine, which act beneficially on glucose metabolism and blood pressure. However, high consumption of protein-rich animal food is also associated with adverse health effects and higher risk for noncommunicable diseases, partly related to other components of these foods, like saturated fatty acids and potential carcinogens in processed meat but also the atherogenic methionine metabolite homocysteine. In moderation, however, animal proteins are especially important for health maintenance in vulnerable persons.

Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality

IMPORTANCE

Defining what represents a macronutritionally balanced diet remains an open question and a high priority in nutrition research. Although the amount of protein may have specific effects, from a broader dietary perspective, the choice of protein sources will inevitably influence other components of diet and may be a critical determinant for the health outcome.

OBJECTIVE

To examine the associations of animal and plant protein intake with the risk for mortality.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study of US health care professionals included 131 342 participants from the Nurses' Health Study (1980 to end of follow-up on June 1, 2012) and Health Professionals Follow-up Study (1986 to end of follow-up on January 31, 2012). Animal and plant protein intake was assessed by regularly updated validated food frequency questionnaires. Data were analyzed from June 20, 2014, to January 18, 2016.

MAIN OUTCOMES AND MEASURES

Hazard ratios (HRs) for all-cause and cause-specific mortality.

RESULTS

Of the 131 342 participants, 85 013 were women (64.7%) and 46 329 were men (35.3%) (mean [SD] age, 49 [9] years). The median protein intake, as assessed by percentage of energy, was 14% for animal protein (5th-95th percentile, 9%-22%) and 4% for plant protein (5th-95th percentile, 2%-6%). After adjusting for major lifestyle and dietary risk factors, animal protein intake was not associated with all-cause mortality (HR, 1.02 per 10% energy increment; 95% CI, 0.98-1.05; P for trend = .33) but was associated with higher cardiovascular mortality (HR, 1.08 per 10% energy increment; 95% CI, 1.01-1.16; P for trend = .04). Plant protein was associated with lower all-cause mortality (HR, 0.90 per 3% energy increment; 95% CI, 0.86-0.95; P for trend < .001) and cardiovascular mortality (HR, 0.88 per 3% energy increment; 95% CI, 0.80-0.97; P for trend = .007). These associations were confined to participants with at least 1 unhealthy lifestyle factor based on smoking, heavy alcohol intake, overweight or obesity, and physical inactivity, but not evident among those without any of these risk factors. Replacing animal protein of various origins with plant protein was associated with lower mortality. In particular, the HRs for all-cause mortality were 0.66 (95% CI, 0.59-0.75) when 3% of energy from plant protein was substituted for an equivalent amount of protein from processed red meat, 0.88 (95% CI, 0.84-0.92) from unprocessed red meat, and 0.81 (95% CI, 0.75-0.88) from egg.

CONCLUSIONS AND RELEVANCE

High animal protein intake was positively associated with cardiovascular mortality and high plant protein intake was inversely associated with all-cause and cardiovascular mortality, especially among individuals with at least 1 lifestyle risk factor. Substitution of plant protein for animal protein, especially that from processed red meat, was associated with lower mortality, suggesting the importance of protein source.

Fruit and vegetables consumption and incident hypertension: dose-response meta-analysis of prospective cohort studies

The role of dietary factors on chronic diseases seems essential in the potentially adverse or preventive effects. However, no evidence of dose-response meta-analysis of prospective cohort studies has verified the association between the intake of fruit and/or vegetables and the risk of developing hypertension. The PubMed and Embase were searched for prospective cohort studies. A generic inverse-variance method with random effects model was used to calculate the pooled relative risks (RRs) and 95% confidence intervals (CIs). Generalized least squares trend estimation model was used to calculate the study-specific slopes for the dose-response analyses. Seven articles comprised nine cohorts involving 185 676 participants were assessed. The highest intake of fruit or vegetables separately, and total fruit and vegetables were inversely associated with the incident risk of hypertension compared with the lowest level, and the pooled RRs and 95% CIs were 0.87 (0.79, 0.95), 0.88 (0.79, 0.99) and 0.90 (0.84, 0.98), respectively. We also found an inverse dose-response relation between the risk of developing hypertension and fruit intake, and total fruit and vegetables consumption. The incident risk of hypertension was decreased by 1.9% for each serving per day of fruit consumption, and decreased by 1.2% for each serving per day of total fruit and vegetables consumption. Our results support the recommendation to increase the consumption of fruit and vegetables with respect to preventing the risk of developing hypertension. However, further large prospective studies and long-term high-quality randomized controlled trials are still needed to confirm the observed association.

Dietary Oily Fish Intake and Blood Pressure Levels: A Population-Based Study

The effect of fish consumption on blood pressure is controversial. The authors measured blood pressure and calculated oily fish servings per week in 677 community-dwellers aged 40 years and older living in rural coastal Ecuador. Using regression models with linear splines, the authors evaluated whether dietary fish intake was related to blood pressure levels, after adjusting for relevant confounders. Mean oily fish consumption was 9.1±5.6 servings per week. There was a nonlinear relationship between systolic pressure and fish servings. In the group of individuals consuming up to five servings per week, each serving significantly reduced systolic pressure by 2.3 mm Hg (P=.020). Any extra serving provided no further effects. The study shows an inverse relationship between oily fish consumption and systolic pressure. Currently recommended amounts of dietary oily fish intake per week (1-2 servings) might be insufficient to exert beneficial effects of fish in the control of blood pressure.

An Update on Nutrients and Blood Pressure

Adverse blood pressure (BP) is a major independent risk factor for epidemic cardiovascular diseases affecting almost one-quarter of the adult population worldwide. Dietary intake is a major determinant in the development and progression of high BP. Lifestyle modifications, including recommended dietary guidelines, are advocated by the American Society of Hypertension, the International Society of Hypertension, the Japanese Society of Hypertension, and many other organisations for treating all hypertensive people, prior to initiating drug therapy and as an adjunct to medication in persons already on drug therapy. Lifestyle modification can also reduce high BP and prevent development of hypertension. This review synthesizes results from the International Study of Macro/Micronutrients and Blood Pressure (INTERMAP), a cross-sectional epidemiological study of 4,680 men and women aged 40-59 years from Japan, the People's Republic of China, the United Kingdom, and the United States, published over the past few years on cross cultural BP differences. INTERMAP has previously reported that intakes of vegetable protein, glutamic acid, total and insoluble fibre, total polyunsaturated fatty acid and linoleic acid, total n-3 fatty acid and linolenic acid, phosphorus, calcium, magnesium, and non-heme iron were inversely related to BP. Direct associations of sugars (fructose, glucose, and sucrose) and sugar-sweetened beverages (especially combined with high sodium intake), cholesterol, glycine, alanine, and oleic acid from animal sources with BP were also reported by the INTERMAP Study.

Dietary proteins improve endothelial function under fasting conditions but not in the postprandial state, with no effects on markers of low-grade inflammation

Endothelial dysfunction (ED) and low-grade inflammation (LGI) have a role in the development of CVD. The two studies reported here explored the effects of dietary proteins and carbohydrates on markers of ED and LGI in overweight/obese individuals with untreated elevated blood pressure. In the first study, fifty-two participants consumed a protein mix or maltodextrin (3×20 g/d) for 4 weeks. Fasting levels and 12 h postprandial responses of markers of ED (soluble intercellular adhesion molecule 1 (sICAM), soluble vascular cell adhesion molecule 1 (sVCAM), soluble endothelial selectin and von Willebrand factor) and markers of LGI (serum amyloid A, C-reactive protein and sICAM) were evaluated before and after intervention. Biomarkers were also combined into mean Z-scores of ED and LGI. The second study compared 4 h postprandial responses of ED and LGI markers in forty-eight participants after ingestion of 0·6 g/kg pea protein, milk protein and egg-white protein. In addition, postprandial responses after maltodextrin intake were compared with a protein mix and sucrose. The first study showed significantly lower fasting ED Z-scores and sICAM after 4 weeks on the high-protein diet (P≤0·02). The postprandial studies found no clear differences of ED and LGI between test meals. However, postprandial sVCAM decreased more after the protein mix compared with maltodextrin in both studies (P≤0·04). In conclusion, dietary protein is beneficial for fasting ED, but not for fasting LGI, after 4 weeks of supplementation. On the basis of Z-scores, postprandial ED and LGI were not differentially affected by protein sources or carbohydrates.

Increased protein intake is associated with uncontrolled blood pressure by 24-hour ambulatory blood pressure monitoring in patients with type 2 diabetes

OBJECTIVE

To analyze possible associations of dietary components, especially protein intake, with blood pressure (BP) during ambulatory BP monitoring (ABPM) in patients with type 2 diabetes.

METHODS

In this cross-sectional study, BP of outpatients with type 2 diabetes was evaluated by 24-hour ABPM (Spacelabs 90207) and usual diet by 3-day weighed diet records. Patients were divided into 2 groups according to their daytime ABPM: uncontrolled BP (systolic BP ≥ 135 mmHg or diastolic BP ≥ 85 mmHg) and controlled BP (systolic BP < 135 mmHg and diastolic BP < 85 mmHg). Logistic regression models unadjusted and adjusted for possible confounders (covariates) were used to analyze the association of protein and uncontrolled BP.

RESULTS

A total of 121 patients with type 2 diabetes aged 62.3 years, 54.5% of whom were women, were studied. The uncontrolled BP group had higher glycated hemoglobin (HbA1C) values (8.4 ± 2.0 vs 7.6 ± 1.3%; p = 0.04) and consumed more protein (20.0 ± 3.8 vs 18.2 ± 3.6% of energy; p = 0.01) and meat, (2.6 [1.45, 2.95] vs 2.0 [1.49, 2.90] g/kg weight; p = 0.04) than the controlled BP group. In a multivariate analysis, protein intake (% of energy) increased the chance for uncontrolled BP (odds ratio [OR] = 1.16; 95% confidence interval [CI], 1.02, 1.30; p = 0.02), adjusted for body mass index (BMI), HbA1C, low-density lipoprotein (LDL) cholesterol, number of antihypertensive medications, and ethnicity. Meat consumption higher than 3.08 g/kg weight/day more than doubled the chance for uncontrolled BP (OR = 2.53; 95% CI, 1.01, 7.60; p = 0.03).

CONCLUSION

High protein intake and meat consumption were associated with high daytime ABPM values in patients with type 2 diabetes. Reducing meat intake might represent an additional dietary intervention in hypertensive patients with type 2 diabetes.

Diets higher in protein predict lower high blood pressure risk in Framingham Offspring Study adults

BACKGROUND

Short-term clinical trials suggest that dietary protein lowers blood pressure (BP); however, long-term effects of total, animal, and plant proteins are less clear. Our goal was to evaluate effects of these dietary proteins on mean systolic BP (SBP) and diastolic BP (DBP) and incident high BP (HBP) risk among middle-aged adults in the Framingham Offspring Study.

METHODS

Men and women (aged 30-54 years) without prevalent HBP, cardiovascular disease, or diabetes with 3-day dietary records from exams 3 or 5 (n = 1,361) were included and followed for a mean of 11.3 years for development of HBP. Protein intakes adjusted for body size were derived using the residual method. Analysis of covariance and Cox proportional hazard's models were used to adjust for age, sex, education, height, activity, smoking, fat calories, diet quality, and body mass index.

RESULTS

Higher protein intakes were associated with lower mean SBP and DBP. Both animal and plant proteins lowered BP and led to statistically significant reductions in HBP risk (hazard ratios of 0.68 and 0.51, respectively). Participants in the highest tertile of total protein intake had 40% less risk (95% confidence interval [CI], 0.45-0.78) of developing HBP. Beneficial effects of protein were apparent for men and women and for normal-weight and overweight individuals. Higher protein diets also characterized by higher fiber intakes led to a 59% reduction (95% CI, 0.37-0.66) in HBP risk.

CONCLUSIONS

Adults consuming more dietary protein from either plant or animal sources had lower long-term risks of HBP.

Effects of protein intake on blood pressure, insulin sensitivity and blood lipids in children: a systematic review

High protein intake in early childhood is associated with obesity, suggesting possible adverse effects on other cardiometabolic outcomes. However, studies in adults have suggested beneficial effects of protein intake on blood pressure (BP) and lipid profile. Whether dietary protein intake is associated with cardiovascular and metabolic health in children is unclear. Therefore, we aimed to systematically review the evidence on the associations of protein intake with BP, insulin sensitivity and blood lipids in children. We searched the databases Medline, Embase, Cochrane Central and PubMed for interventional and observational studies in healthy children up to the age of 18 years, in which associations of total, animal and/or vegetable protein intake with one or more of the following outcomes were reported: BP; measures of insulin sensitivity; cholesterol levels; or TAG levels. In the search, we identified 6636 abstracts, of which fifty-six studies met all selection criteria. In general, the quality of the included studies was low. Most studies were cross-sectional, and many did not control for potential confounders. No overall associations were observed between protein intake and insulin sensitivity or blood lipids. A few studies suggested an inverse association between dietary protein intake and BP, but evidence was inconclusive. Only four studies examined the effects of vegetable or animal protein intake, but with inconsistent results. In conclusion, the literature, to date provides insufficient evidence for effects of protein intake on BP, insulin sensitivity or blood lipids in children. Future studies could be improved by adequately adjusting for key confounders such as energy intake and obesity.

Dietary Habits and Cardiometabolic Health in Obese Children

BACKGROUND

Prevalence rates of cardiometabolic risk factors vary largely among overweight children. This study investigated the relationships between dietary habits and cardiometabolic health among obese children living in a city of Northern Italy.

METHODS

Dietary habits were collected in 448 obese subjects aged 6-18 years, attending an obesity outpatient center in Milan. Anthropometry, blood pressure (BP), lipids, fasting and post-load glucose, and insulin were measured. Physical activity was assessed in adolescents using a questionnaire.

RESULTS

Frequency of glucose intolerance, hypertension and dyslipidemia was 0.7%, 13% and 27.2%, respectively. Plausible reporters consumed more animal protein and sodium and less legumes than recommended in nutritional recommendations and adequate amounts of fiber mainly derived from whole grains. Subjects skipping breakfast had unhealthy diets and greater body fatness. After adjustment for confounders, waist/height and fasting glucose were associated with sodium intake (r =0.149 and r = 0.142, respectively; p < 0.05), 2-hour glucose with fiber (r = -0.172; p < 0.01), and BP with vegetable protein intake (systolic r = -0.120 (p < 0.05); diastolic r = -0.267 (p < 0.01)). Hypertensive children consumed less vegetable protein than normotensive children.

CONCLUSIONS

The cardiometabolic health of obese children improves with vegetable protein and whole grain intake, whereas dysglycemia and adiposity increase with sodium intake.