Trends in intake and sources of dietary protein in Korean adults, 1998-2018

Relationship between dietary protein and amino acid intake and handgrip strength in Korean adults: data from the 2014-2019 Korea National Health and Nutrition Examination Survey

BACKGROUND

Sarcopenia contributes to an increased risk of falls and fractures, and reduced mobility, and mortality. Supplementation with dietary protein and amino acids has been suggested as a potential strategy to slow or prevent the associated loss of muscle mass and strength. However, most previous studies have focused on dietary protein or limited populations, such as older adults. Therefore, this study aimed to investigate the relationship between dietary protein and amino acid intake and handgrip strength (HG) in Korean adults.

METHODS

This study used data from the 2014-2019 Korea National Health and Nutrition Examination Survey. A total of 18,565 adults who participated in a 1-day 24-hour recall method were included. Protein intake was calculated as a percentage of total energy intake from food sources (animal and plant). Amino acid intake (g/day), including essential amino acids (EAAs), branched-chain amino acids (BCAAs), and non essential amino acids (NEAAs), was assessed using a database expanded based on amino acid composition databases constructed by national institutions. Low HG was diagnosed based on the 2019 guidelines of the Asian Working Group on Sarcopenia.

RESULTS

In the fully adjusted model, total and plant protein intakes were positively associated with HG levels (kg) (β = 0.04 and 0.07 per 1% increase, respectively; p < 0.05 for both). Participants aged ≥ 65 years in the highest NEAA intake group had a 42% lower risk of low HG compared to those in the lowest intake group (odds ratio 0.58; 95% confidence interval 0.35-0.97; p for trend = 0.1026). A lower risk of HG was observed in older participants whose plant protein intake ranged from 8 to 10% of energy, compared to those consuming less than 7%. However, no association was found when intake exceeded 10% of energy.

CONCLUSIONS

These findings suggest that a high intake of NEAAs and a moderately high intake of plant protein may be associated with a lower risk of low HG among Korean older adults. Further prospective studies are needed to explore the effects of protein and amino acid intake on muscle mass and strength.

Dietary modulation for the hypertension risk group in Koreans: a cross-sectional study

BACKGROUND

Hypertension (HTN) is a critical global health issue, contributing to high morbidity and mortality rates. Representative risk factors for HTN include aging, genetics, obesity, alcohol drinking, smoking, and diet. Dietary interventions like the Dietary Approaches to Stop HTN (DASH) diet plan effectively prevent and manage HTN. We intend to evaluate the influence of eating patterns on HTN, applying multiple risk factors.

METHODS

For cross-sectional design, study subjects were grouped into four groups: optimal (n = 7,712), normal (n = 1,220), high normal (n = 3,655), and HTN (n = 4,355) according to the 2022 HTN treatment guidelines of Korea. Factor analysis was performed to identify major dietary patterns based on nutritional data obtained from a brief dietary questionnaire, including 17 food items. Finally, we conducted a moderation analysis to evaluate the impact of dietary patterns on the HTN risk score, which is determined by genetic variables, body mass index, alcohol consumption, and smoking status.

RESULTS

We identified three principal dietary patterns (Korean, Western, and New diet) in the study population. Adherence to the New diet was linked to lower HTN risk in all models (p < 0.001), while the Western and Korean diets were associated with a higher risk of HTN in some models. In high HTN-risk individuals, adherence to the Western diet increased the HTN risk trend (p < 0.001), whereas the New diet showed a potential protective trend (p = 0.059).

CONCLUSIONS

The nutritional moderation effect was evident in the HTN high-risk group, where the Western diet increased risk, while the New diet showed a borderline protective effect. If the findings are validated by longitudinal investigation, our findings could serve as the basis for developing dietary guidelines for HTN.

Association between carbohydrate to protein or fat ratio and mortality: A prospective cohort study

BACKGROUND & AIMS

The effect of dietary macronutrient balance on longevity and metabolic health remains a subject of considerable interest. We aimed to investigate the association of carbohydrate-to-protein and carbohydrate-to-fat ratios with all-cause and cardiovascular mortalities.

METHODS

In this population-based study, data from the Korean Genome and Epidemiology Study were integrated with those from national data sources, including mortality records from the Korea National Statistical Office. The primary outcomes were all-cause and cardiovascular mortalities. Carbohydrate-to-protein and carbohydrate-to-fat ratios were evaluated based on dietary habits assessed through a food frequency questionnaire. Harrell's C-index was employed to determine optimal cut-off points for carbohydrate-to-protein and carbohydrate-to-fat ratios. Cox proportional hazards regression models were used to assess associations.

RESULTS

A total of 143,050 participants aged ≥40 years were included in the analyses. Compared with individuals with non-elevated carbohydrate-to-protein ratios (<5.2), those with elevated carbohydrate-to-protein ratios (>9.9) exhibited a higher all-cause mortality (hazard ratio 1.09, 95% confidence interval 1.01-1.17); however, no correlation between carbohydrate-to-protein ratio and cardiovascular mortality (hazard ratio 1.13, 95% confidence interval 0.96-1.32) was observed. Compared with those with non-elevated carbohydrate-to-fat ratios (<5.1), those with higher carbohydrate-to-fat ratios (>7.1) exhibited increased all-cause (hazard ratio 1.08, 95% confidence interval 1.00-1.16) and cardiovascular (hazard ratio 1.27, 95% confidence interval 1.06-1.52) mortalities.

CONCLUSIONS

Our findings regarding macronutrient ratios and their association with mortality suggest that reducing excessive carbohydrate intake and increasing the consumption of protein and fats may have beneficial effects on longevity and cardiovascular health. Further studies are needed to understand the underlying mechanisms of these effects.

Association between dietary protein intake and risk of chronic kidney disease: a systematic review and meta-analysis

Objective

There is suggestive data indicating a correlation among dietary protein intake and the progression of chronic kidney disease (CKD). Nonetheless, the exact associations between dietary protein intake and the incidence of CKD have remained uncertain. We performed the first meta-analysis to explore the correlation among total protein, plant protein, animal protein intake and CKD risk.

Methods

The study conformed the PRISMA statement guidelines. We comprehensively searched PubMed, Web of Science, and Embase until to December 2023. The retrieved studies underwent rigorous evaluation for eligibility, and relevant data were meticulously extracted. The Newcastle-Ottawa Scale (NOS) tool was applied to evaluate the risk of bias. Subsequently, relevant data were extracted and pooled to evaluate the relations among dietary protein intake and CKD incidence.

Results

Totally, 6,191 articles were identified, six studies were eligible. A total of 148,051 participants with 8,746 CKD cases were included. All studies had a low overall risk of bias. Higher total, plant and animal protein intake were all correlated with decreased CKD incidence, pooled risk ratios (RRs) and 95% confidence intervals (CIs) were as follows: (RR = 0.82, 95% CI = 0.71-0.94, p = 0.005; I2 = 38%, p = 0.17); (RR = 0.77, 95% CI = 0.61-0.97, p = 0.03; I2 = 77%, p = 0.001); (RR = 0.86, 95% CI = 0.76-0.97, p = 0.02; I2 = 0%, p = 0.59), respectively. For fish and seafood within animal protein: RR = 0.84, 95% CI = 0.74-0.94. Subgroup analysis showed that geographical region, sample size, follow-up time, not assessing protein by food frequency questionnaire, using %energy as the measurement index, not adjusting for several covariates may be the sources of heterogeneity for plant protein. A significant non-linear relation among plant protein and incident CKD was observed by dose-response analysis.

Conclusion

The data showed a lower CKD risk significantly associated higher-level dietary total, plant or animal protein (especially for fish and seafood) intake. Further prospective studies demonstrating the correlations of precise sources, intake and duration of dietary protein and incident CKD are warranted.

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

Background

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

Objective

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

Methods

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

Results

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

Conclusion

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

Individual components of post-hepatectomy care pathways have differential impacts on length of stay

BACKGROUND

The value of individual variable contributions to post-hepatectomy length of stay (LOS) are difficult to quantify within bundled care pathways.

METHODS

Poisson regression and marginal effects models for prolonged post-hepatectomy LOS (>25% median) included Kawaguchi-Gayet (KG) complexity, perioperative variables, and pathways (minimally-invasive = MIS; low-intermediate-risk = KGI/II; high-risk = KGIII; combination).

RESULTS

Median LOS was 2, 4, 5, and 5 days for MIS, KGI/II, KGIII and combination pathways (N = 978). Poisson regression identified age, intraoperative fluids, delayed diet tolerance, and combination cases as associated with increased LOS (p < 0.01). Marginal effects analysis demonstrated the following added probability of longer LOS: each year of age 0.03x, 250 mL intraoperative fluids 0.06x, each operative hour 0.2x, additional day before diet tolerance 0.4x, combination cases 0.7x. MIS was associated with 1.2x increased probability of shorter LOS.

CONCLUSIONS

Optimizing intraoperative fluids, operative time, and postoperative diet, while favoring MIS approach when feasible, may maximize effects of post-hepatectomy care pathways to reduce LOS.

Low-protein diet is inversely related to the incidence of chronic kidney disease in middle-aged and older adults: results from a community-based prospective cohort study

PURPOSE

Dietary protein intake can modulate renal health. However, the effect of dietary protein restriction on kidney function in the general population remains unclear. This study aimed to examine the association between total protein intake and new-onset chronic kidney disease (CKD) in Korean adults.

METHODS

We included 7339 participants from the Korean Genome and Epidemiology Study. Participants were divided into low-protein diet (LPD, < 0.8 g/kg/day), normal-protein diet (NPD, 0.8-1.3 g/kg/day), and high-protein diet (HPD, > 1.3 g/kg/day) groups. New-onset CKD was defined as two consecutive events of estimated glomerular filtration rate < 60 mL/min/1.73 m². Multivariable Cox hazard regression analysis was conducted to examine the association of total protein intake with new-onset CKD. Subgroup analyses according to diabetes mellitus (DM) status were performed. We performed the same analyses by dividing participants into total protein, plant protein, and animal protein intake tertiles.

RESULTS

During a median follow-up of 13.7 years, 633 (8.7%) participants newly developed CKD. The fully adjusted hazard ratios (HR) with 95% confidence interval (CI) for incident CKD of the LPD and HPD groups compared with the NPD group were 1.49 (1.18-1.87) and 0.63 (0.45-0.87), respectively. The HR (95% CI) of the highest tertile group of plant protein intake for incident CKD was 0.72 (0.54-0.93), compared with that of the lowest tertile group. Similar trends were observed only in the non-DM subgroup, not in the DM subgroup.

CONCLUSION

Protein intake, especially plant proteins, was negatively associated with the incidence of new-onset CKD in middle-aged and older Korean adults.

The Association Between Total Protein Intake and All-Cause Mortality in Middle Aged and Older Korean Adults With Chronic Kidney Disease

Background and Aims

Over the past decades, the optimum protein intake for patients with chronic kidney disease (CKD) has been an important, controversial issue. Dietary protein restriction has been commonly recommended for patients with CKD for preserving kidney function. However, evidence of the associations between long-term protein intake and mortality is not consistent in patients with CKD. Therefore, we aimed to examine the associations between total protein intake and all-cause mortality in Korean adults with CKD.

Methods

From three sub-cohorts of the Korean Genome and Epidemiology Study (KoGES) starting from 2001, total 3,892 participants with eGFR < 60 mL/min/1.73 m² (CKD stage 3–5) were included in this study. Dietary data were collected using food-frequency questionnaires at baseline. Deaths were followed from 2001 to 2019. Cox proportional hazards regression model was used to evaluate the association between protein intake and all-cause mortality.

Results

During a median follow-up (min-max) of 11.1 years (0.3–15.1), 602 deaths due to all causes of mortality were documented. After adjustment for covariates, higher total protein intake was not associated with all-cause mortality [highest vs. lowest quintile of total protein intake (g/kg/day) and proportion (%) (Q5 vs. Q1), HR = 1.14 (0.75–1.72), and HR = 0.87 (0.67–1.13)] in CKD stage 3–5 patients.

Conclusion

Dietary protein intake was not associated with mortality from all causes in patients with CKD. Further research is needed to establish optimal protein intake levels and examine the impact of the dietary source of protein on various health outcomes and mortality in CKD.