Protein intakes and serum albumin levels in a Japanese general population: NIPPON DATA90

Associations of serum albumin and dietary protein intake with all-cause mortality in community-dwelling older adults at risk of sarcopenia

Objective

The Asian Working Group for Sarcopenia 2019 consensus emphasized nutritional assessment and intervention for community-dwelling older people with sarcopenia status. This study aimed to examine the association of serum albumin and dietary protein intake (DPI) with all-cause mortality among older adults at risk of sarcopenia.

Methods

We enrolled 1763 older adults at risk of sarcopenia in the Chinese Longitudinal Healthy Longevity Survey (2012-2018) using calf circumference and handgrip strength. Serum albumin concentrations were measured using bromocresol green methods, and DPI frequency was evaluated using a semi-quantitative questionnaire at baseline. Cox proportional hazards models were used to explore the association of serum albumin and DPI with all-cause mortality.

Results

During 5606.3 person-years of follow-up (median: 3.28 years), 802 older people died. After adjusting for socio-demographics, health behaviors, and clinical characteristics, we observed an inverse linear association between serum albumin and all-cause mortality (Pnon-linear = 0.429). Participants with low albumin levels (<40.0 g/L) had a 43 % higher risk of mortality than their counterparts (hazard ratio (HR) = 1.43, 95 % confidence interval (CI) = 1.22-1.66). There was no significant association between DPI and mortality (Ps > 0.05). Moreover, the association between low albumin and all-cause mortality remained significant in the lower DPI subgroup (HR = 1.47, 95 % CI = 1.18-1.85), but was not significant in the high DPI subgroup (HR = 1.15, 95 % CI = 0.92-1.39).

Conclusions

Serum albumin levels are inversely associated with all-cause mortality in community-based older adults at risk of sarcopenia. Sufficient dietary protein consumption may attenuate the effect of low serum albumin on increased mortality and potential mechanisms for the interaction warrant further exploration.

Dietary protein intake and all-cause mortality: results from The Kawasaki Aging and Wellbeing Project

BACKGROUND

Increased protein intake has been recommended to prevent sarcopenia/frailty, reports on the quantity and quality of protein intake needed and the associated prognosis, particularly in the aging population of Asia, are limited. In this study, we aimed to investigate the relationship between protein intake and mortality in Japanese individuals, aged 85 years and older.

METHODS

The data were obtained from The Kawasaki Aging and Wellbeing Project, which is a prospective cohort study of older adults aged between 85 and 89 years with no physical disability at baseline. Of the 1,026 adults in the cohort, 833 were included in the analysis, after excluding those who had not completed a brief, self-administered diet history questionnaire or those who scored less than 24 on the Mini-Mental State Examination. The participants were grouped into quartiles based on protein intake: Q1 (protein < 14.7, %Energy), Q2 (14.7 ≤ protein < 16.7, %Energy), Q3 (16.7 ≤ protein < 19.1, %Energy), and Q4 (≥ 19.1, %Energy). Multivariate Cox proportional hazards models were utilized to evaluate the association between protein intake and all-cause mortality. Kaplan-Meier survival curves were employed to investigate the relationship between protein intake and all-cause mortality.

RESULTS

The mean protein intake of our study population was 17.0% of total energy. Animal protein intake, particularly fish intake, increased significantly along with total protein intake. The study had an average observation period of 1,218 days and recorded 89 deaths. After adjusting for age, sex, skeletal muscle mass index, cardiovascular disease, cancer, education, and serum albumin levels, a lower risk of all-cause mortality was observed in the highest protein intake (Q4) group than in the lowest protein intake (Q1) group (hazard ratio: 0.44, 95% confidence interval: 0.22-0.90, p-value: 0.020).

CONCLUSION

Protein intake is associated with a reduced risk of all-cause mortality in older adults (aged ≥ 85 years) who engage in independent activities of daily living. This association may impact all-cause mortality independent of muscle mass.

The effect of urinary essential and non-essential elements on serum albumin: Evidence from a community-based study of the elderly in Beijing

Background & aims

Few epidemiological studies have investigated the relationships of urinary essential and non-essential elements with serum albumin, an indicator of nutritional status, especially for the elderly in China.

Methods

A community-based study among elderly participants (n = 275) was conducted in Beijing from November to December 2016. We measured 15 urinary elements concentrations and serum albumin levels. Three statistical methods including the generalized linear model (GLM), quantile g-computation model (qgcomp) and bayesian kernel machine regression (BKMR) were adapted.

Results

In GLM analysis, we observed decreased serum albumin levels associated with elevated urinary concentrations of aluminum, arsenic, barium, cobalt, chromium, copper, iron, manganese, selenium, strontium, and zinc. Compared with the lowest tertile, the highest tertile of cadmium and cesium was also negatively associated with serum albumin. Urinary selenium concentration had the most significant negative contribution (30.05%) in the qgcomp analysis. The negative correlations of element mixtures with serum albumin were also observed in BKMR analysis.

Conclusions

Our findings suggested the negative associations of essential and non-essential elements with serum albumin among the elderly. Large-scare cohort studies among the general population are required to validate our findings and elucidate the relevant underlying mechanisms.

Serum Albumin and Risks of Stroke and Its Subtypes - The Circulatory Risk in Communities Study (CIRCS)

BACKGROUND

Few studies have investigated the association between serum albumin levels and the risk of stroke subtypes among the general Japanese population.Methods and Results:In this study, 5,071 men and 7,969 women aged 40-74 years, initially free from stroke, coronary artery disease, and kidney and hepatic failure, and residing in 4 Japanese communities completed a baseline risk factor survey between 1985 and 1994. During the 24-year follow-up, 528 men and 553 women experienced stroke. In the entire study cohort, multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) of total stroke, ischemic stroke, and intracerebral hemorrhage for the lowest vs. highest quartiles of serum albumin were 1.45 (1.18-1.77), 1.52 (1.17-1.97), and 1.57 (1.04-2.37), respectively. In men, multivariable HRs (95% CIs) for total stroke, ischemic stroke, and intracerebral hemorrhage in the lowest vs. highest serum albumin quartile were 1.44 (1.07-1.92), 1.48 (1.03-2.11) and 1.71 (0.92-3.18), respectively, whereas in women they were 1.50 (1.13-1.99), 1.63 (1.11-2.39), and 1.56 (0.89-2.74), respectively. Similar inverse associations were observed for each of the ischemic stroke subtypes, but not for subarachnoid hemorrhage.

CONCLUSIONS

Low serum albumin levels were associated with an increased risk of total stroke, ischemic stroke, ischemic stroke subtypes, and intracerebral hemorrhage.

Pesticide Exposure and Stunting among Children in Agricultural Areas

BACKGROUND

The prevalence of growth disorders among school-aged children in Indonesia is high (30.7%). Pesticides have been massively used in Indonesian agricultural areas.

OBJECTIVE

To determine if exposure to pesticides is associated with stunting among children in agricultural areas.

METHODS

This case-control study included 160 children (48 cases and 112 controls) aged 8-12 years. Exposure to pesticides was measured based on the history of the exposure since perinatal period, infancy, and childhood of the participants. Stunting was determined as a height for age z-score (HAZ) < ‑2 SD. Other variables measured were levels of thyroid stimulating hormone (TSH), insulin-like growth factor-1 (IGF-1), hemoglobin, zinc, albumin, nutrient adequacy level (energy and protein), and history of infection, low-birth weight (LBW), and mother's height.

RESULTS

There were no significant difference between the cases and controls in terms of in the baseline characteristics, except for the median IGF-1 level; it was significantly (p<0.001) lower in the cases (66.73 ng/mL) than the controls (112.57 ng/mL). High level of pesticide exposure (p=0.029) and low IGF-1 levels (p<0.001) were significantly associated with stunting. After adjusting for confounding variables, these variables were found to be independent risk factors for stunting in children (aOR 3.90, 95% CI 1.15 to 13.26; and aOR 8.35, 95% CI 3.65 to 19.14, respectively).

CONCLUSION

Pesticide exposure could be a risk factor for the occurrence of growth disorders in children living in agricultural areas. Necessary actions should be taken to protect children living in agricultural areas from exposure to pesticides.

Age-related reduction and independent predictors of toe flexor strength in middle-aged men

Background

Toe flexor muscles play an important role in posture and locomotion, and poor toe flexor strength is a risk factor for falls. In this cross-sectional study, we estimated the age-related change in toe flexor strength and compared it with that of handgrip strength. Independent factors predicting toe flexor and handgrip strength were also determined.

Methods

A total of 1401 male (aged 35–59 years) study participants were divided into five groups according to their chronological age; 35–39, 40–44, 45–49, 50–54, and 55–59 years. Toe flexor and handgrip strength, anthropometry, and resting blood pressure were measured. Fasting blood samples were collected to measure blood glucose, triglycerides, high- and low-density lipoprotein-cholesterols, and albumin. A self-administered lifestyle questionnaire was conducted.

Results

Decline in absolute toe flexor and handgrip strength began in the age groups 50–55 and 55–59 years, respectively. In comparison to the mean values of the youngest group, relative toe flexor strength (87.0 ± 26.6%) was significantly lower than handgrip strength (94.4 ± 13.1%) for the oldest group. Multiple regression analyses showed that independent factors predicting both toe flexor and handgrip strength were lean body mass, age, serum albumin, drinking habit, and fat mass. Additionally, fasting blood glucose, diastolic blood pressure, sleeping time and exercise habit were predicting factors of toe flexor strength but not of handgrip strength.

Conclusions

Age-related reduction in toe flexor strength was earlier and greater than handgrip strength, and toe flexor strength reflects body composition and metabolic status.

Serum Albumin Levels and Economic Status in Japanese Older Adults

BACKGROUND

Low serum albumin levels are associated with aging and medical conditions such as cancer, liver dysfunction, inflammation, and malnutrition and might be an independent predictor of long-term mortality in healthy older populations. We tested the hypothesis that economic status is associated with serum albumin levels and explained by nutritional and health status in Japanese older adults.

DESIGN

We performed a cross-sectional analysis using data from the Japan Gerontological Evaluation study (JAGES). The study participants were 6528 functionally independent residents (3189 men and 3339 women) aged ≥65 years living in four municipalities in Aichi prefecture. We used household income as an indicator of economic status. Multiple linear regression was used to compare serum albumin levels in relation to household income, which was classified as low, middle, and high. Additionally, mediation by nutritional and health-related factors was analyzed in multivariable models.

RESULTS

With the middle-income group as reference, participants with low incomes had a significantly lower serum albumin level, even after adjustment for sex, age, residential area, education, marital status, and household structure. The estimated mean difference was -0.17 g/L (95% confidence interval, -0.33 to -0.01 g/L). The relation between serum albumin level and low income became statistically insignificant when "body mass index", "consumption of meat or fish", "self-rated health", "presence of medical conditions", "hyperlipidemia", or "respiratory disease "was included in the model.

CONCLUSION

Serum albumin levels were lower in Japanese older adults with low economic status. The decrease in albumin levels appears to be mediated by nutrition and health-related factors with low household incomes. Future studies are needed to reveal the existence of other pathways.

Medium-chain triacylglycerol suppresses the decrease of plasma albumin level through the insulin-Akt-mTOR pathway in the livers of malnourished rats

Recent studies have shown that medium-chain triacylglycerol (MCT) improved serum albumin concentration in elderly people with protein-energy malnutrition (PEM) and in malnourished rats. However, the mechanism for this effect has not been clarified. Dietary MCT promotes insulin secretion from the pancreas, and insulin activates mammalian target of rapamycin (mTOR) complex 1 (mTORC1) via the activation of phosphoinositide 3-kinase (PI3K) and its downstream effecter, Akt. mTORC1 promotes mRNA translation through S6K and 4E-BP1. Therefore, we hypothesized that dietary MCT elevates albumin synthesis through promotion of insulin-Akt-mTOR transduction in the liver. To test this hypothesis, we measured phosphorylated Akt, mTOR and albumin in the livers of malnourished rats. In the present study we examined rats fed low-protein diets containing either MCT or long-chain triacylglycerol (LCT) with energy restriction. The plasma and liver albumin levels were significantly higher in the MCT-fed group than in the LCT-fed group. In addition, plasma insulin concentration, liver phosphorylated Akt/Akt and phosphorylated mTOR/mTOR levels were significantly higher in the MCT-fed group than in the LCT-fed group. These results suggest that one of the mechanisms for the albumin improvement effect of dietary MCT is the promotion of albumin synthesis through the insulin-Akt-mTOR signaling pathway of the liver.

Serum anion gap is predictive of mortality in an elderly population

An elevated serum anion gap is known to be associated with hypertension, low cardiorespiratory fitness, and decreased renal function. We evaluated whether serum AG might be predictive of elderly mortality in a community-based cohort in Korea. We analyzed the available data from 862 elderly people in the Korean Longitudinal Study on Health and Aging. Over a 5-year observational period, 151/862 (17.5%) participants died, and a high albumin-adjusted anion gap (SAAG) was associated with an increased risk of all-cause mortality in unadjusted analyses (hazard ratio [HR], 1.96; 95% confidence interval [CI], 1.41-2.71) and fully adjusted analyses (HR, 1.77; 95% CI, 1.24-2.52), compared with a low SAAG group. The population attributable fraction of death due to high SAAG was 38.2% (95% CI 20.7-58.2%). In particular, the participants with high SAAG had higher cardiovascular and infection-related mortality rates than those with low SAAG (HR, 2.11; 95% CI, 1.06-4.19, and HR, 9.69; 95% CI, 1.12-83.4, respectively). High SAAG may be an independent predictor of mortality and is associated with higher cardiovascular and infection related mortality in the elderly.

Effects of Ginkgo biloba extract on the pharmacokinetics and pharmacodynamics of tolbutamide in protein-restricted rats

Objectives

Effects of repeated administration of Ginkgo biloba extract on pharmacokinetics and pharmacodynamics of tolbutamide were examined in rats fed a low-protein diet.

Methods

Rats were given a low (7% casein) or control (20% casein) protein diet for 21 days and administered Ginkgo biloba extract (100 mg/kg per day) for the last 5 days. Tolbutamide was co-administered on the last day. Blood glucose and plasma tolbutamide concentrations were determined over the subsequent 12 h and the activity of hepatic cytochrome P450s were determined at 12 h after dosing.

Key findings

There were significant decreases in body weight, the ratio of liver to body weight, and plasma albumin concentrations in rats on the low-protein diet compared with controls. The hypoglycaemic effect of tolbutamide was significantly greater and the concentration of the drug in plasma was higher in the former group. The repeated administration of Ginkgo biloba extract had little influence on the hypoglycaemic effect of tolbutamide, but tended to decrease the drug concentration in plasma of control rats, while it reduced significantly the hypoglycaemic action and plasma concentration of tolbutamide in the protein-restricted rats.

Conclusions

The effects of Ginkgo biloba extract on the pharmacokinetics and pharmacodynamics of tolbutamide were significantly enhanced in rats on the low-protein diet.