Associations of dietary, lifestyle, and sociodemographic factors with iron status in Chinese adults: a cross-sectional study in the China Health and Nutrition Survey

Higher serum ferritins are associated with higher blood pressure: A cross-sectional study

The aim of the study was to investigate the association between serum ferritin and hypertension among American adults from National Health and Nutrition Examination Survey (NHANES) 1999 to 2018. A total of 16,125 participants were included. Weighted logistic regression and subgroup analyses were performed to explore the association. We found that serum ferritin was closely correlated to hypertension. Individuals with high serum ferritin were more likely to have higher systolic or diastolic blood pressure (SBP, DBP) than those with lower serum ferritin. Restricted cubic spline showed a significant non-linear association between serum ferritin and SBP/DBP. Higher level of serum ferritin (Q3 74.1-147 μg/L and Q4 > 147 μg/L) was found to have positive association with high SBP [Q3 (OR: 1.246, 95% CI:1.020-1.523), Q4 (OR: 1.354, 95% CI:1.096-1.674)], and hypertension [Q3 (OR: 1.283, 95% CI:1.099-1.499), Q4 (OR: 1.424, 95% CI:1.197-1.63)] in the whole population. In people aged between 20 and 60, subjects with high serum ferritin were significantly associated with a higher risk of hypertension, but in those over 60, the relationship between serum ferritin level and hypertension is negative. A non-linear association between serum ferritin and SBP, as well as DBP, was discovered. There was age difference in association between serum ferritin and hypertension in American adults, and further researches were needed to understand the mechanisms behind the difference.

Risk prediction of iron deficiency for plasmapheresis donors in China: Development and validation of a prediction model

BACKGROUND AND OBJECTIVES

The present study aims to evaluate the iron stores in plasmapheresis donors and develop and validate an iron deficiency (ID) risk prediction model for plasmapheresis donors with potential or existing ID.

MATERIALS AND METHODS

We assessed plasmapheresis donors' serum ferritin (SF) and haemoglobin (Hb) levels. The candidate factors showing significant differences in the multivariate logistic regression analysis were used to establish a risk prediction scoring system. The participants were divided into a training cohort and an internal validation cohort in a 7:3 ratio. Additional plasmapheresis donors from a different station were recruited for external validation.

RESULTS

The SF levels in both male and female donors in the high-frequency group were significantly lower than those of new donors (male: p < 0.001; female: p = 0.008). The prevalence of ID in female regular donors with a high frequency was significantly higher than that in new donors (33.1% vs. 24.6%; odds ratio = 1.209 [95% CI: 1.035-1.412]). Donation frequency, age, Hb, body mass index and being pre-menopausal were identified as independent risk factors for ID (p < 0.05). The developed model exhibited good discrimination ability (area under the receiver operating characteristic curve >0.7) and calibration (p > 0.05) in development, internal validation cohorts and external validation cohorts.

CONCLUSION

A higher donation frequency has been associated with reduced SF levels and an increased risk of ID in women. The developed ID risk prediction model demonstrates moderate discriminative power and good model fitting, suggesting its potential clinical utility.

Real-world experience of intravenous iron sucrose supplementation and dynamics of soluble transferrin receptor and hepcidin in a Spanish cohort of absolute iron deficient patients

The study evaluated the safety and effectiveness of the generic intravenous (IV) iron treatment (Feriv®), in a Spanish cohort with absolute iron deficiency (ID) (serum ferritin <50 ng/ml, with or without anaemia) (n = 122; 91% women; median age of 44 years [IQR: 33.7-54]). Iron-related biomarkers were measured before treatment (baseline), 2 weeks after beginning the protocol (intermediate control, IC) and between 7 and 10 days after treatment completion (final time-point). Primary efficacy endpoints were ferritin levels ≥ 50 ng/ml, anaemia restoration or an increase in haemoglobin (Hb) of at least one point in patients without baseline anaemia. After treatment, iron-related biomarkers improved, including ferritin, Hb, sideremia, transferrin, transferrin saturation index, soluble transferrin receptor (sTfR), and hepcidin. Baseline ferritin concentration (13.5 ng/ml [IQR: 8-24.2]) increased at the IC and continued rising at the final time-point, reaching a median ferritin of 222 ng/ml and 97.3% of patients ≥ 50 ng/ml. At the final time-point, anaemia prevalence decreased from 26.2% to 5%, while the 34.1% without baseline anaemia showed an increase in Hb of at least one point. Headache was the only drug-adverse event recorded in 2.3% of patients. At a late time-point (27.5 median weeks after ending therapy [IQR: 22-40]), evaluated in a subgroup of 66 patients, 18% had ferritin levels < 50 ng/ml. Multivariate analysis showed that low baseline ferritin and high sTfR/hepcidin ratio tended to be independently associated with ID recurrence. Feriv® is a safe, effective first-line treatment for absolute ID, with improvement of serum ferritin and Hb. ID recurrence was associated with the baseline degree of iron stores depletion, indicated by serum ferritin, and sTfR/hepcidin ratio.

Associations of dietary, sociodemographic, and anthropometric factors with anemia among the Zhuang ethnic adults: a cross-sectional study in Guangxi Zhuang Autonomous Region, China

BACKGROUND

After decades of rapid economic development, anemia remains a significant public health challenge globally. This study aimed to estimate the associations of sociodemographic, dietary, and body composition factors with anemia among the Zhuang in Guangxi Zhuang Autonomous Region, China.

METHODS

Our study population from the baseline survey of the Guangxi ethnic minority Cohort Study of Chronic Diseases consisted of 13,465 adults (6,779 women and 6,686 men) aged 24-82 years. A validated interviewer-administered laptop-based questionnaire system was used to collect information on participants' sociodemographic, lifestyle, and dietary factors. Each participant underwent a physical examination, and hematological indices were measured. Least absolute shrinkage and selection operator (LASSO) regression was used to select the variables, and logistic regression was applied to estimate the associations of independent risk factors with anemia.

RESULTS

The overall prevalences of anemia in men and women were 9.63% (95% CI: 8.94-10.36%) and 18.33% (95% CI: 17.42─19.28%), respectively. LASSO and logistic regression analyses showed that age was positively associated with anemia for both women and men. For diet in women, red meat consumption for 5-7 days/week (OR = 0.79, 95% CI: 0.65-0.98, p = 0.0290) and corn/sweet potato consumption for 5-7 days/week (OR = 0.73, 95% CI: 0.55-0.96, p = 0.0281) were negatively associated with anemia. For men, fruit consumption for 5-7 days/week (OR = 0.75, 95% CI: 0.60-0.94, p = 0.0130) and corn/sweet potato consumption for 5-7 days/week (OR = 0.66, 95% CI: 0.46-0.91, p = 0.0136) were negatively correlated with anemia. Compared with a normal body water percentage (55-65%), a body water percentage below normal (< 55%) was negatively related to anemia (OR = 0.68, 95% CI: 0.53-0.86, p = 0.0014). Conversely, a body water percentage above normal (> 65%) was positively correlated with anemia in men (OR = 1.73, 95% CI: 1.38-2.17, p < 0.0001).

CONCLUSIONS

Anemia remains a moderate public health problem for premenopausal women and the elderly population in the Guangxi Zhuang minority region. The prevention of anemia at the population level requires multifaceted intervention measures according to sex and age, with a focus on dietary factors and the control of body composition.

Diagnosis and treatment of female alopecia: Focusing on the iron deficiency-related alopecia

Objectives

Alopecia is a soft but meaningful complaint affecting women's physical and psychological health. Female alopecia (FA) has diverse etiologies. Nonetheless, FA is stereotyped as female pattern hair loss, also known as female androgenetic alopecia, and has not been thoroughly investigated. This study aimed to identify the etiologies of FA at a tertiary medical center in Eastern Taiwan.

Materials and Methods

This retrospective study enrolled female patients with hair loss who visited the dermatology department of (blinded information). A complete history taking was obtained, including the onset and duration of alopecia, menstruation, gynecologic diseases, psychological stress, underlying diseases, vaccination, and dietary habits, etc., Blood tests were performed, including hemoglobin (Hb), ferritin, Zn, autoimmune and thyroid profiles, etc., Iron deficiency (ID) was defined as serum ferritin level <60 ng/mL. The hair condition, ferritin, and Hb levels were monitored every 3 months after supplementation.

Results

A total of 155 patients were recruited. The etiologies of FA were diverse; the top five etiologies were nutrient deficiencies (83.9%), autoimmune (14.8%) and thyroid (7.7%) diseases, psychological stress (12.3%), and coronavirus disease 2019 (COVID-19) vaccination (6.5%). ID accounted for 70.3% of cases. The disease duration was an important prognostic factor for the improvement of serum ferritin. Patients with subjective improvement of hair regrowth also had more increase of ferritin levels after iron supplementation. The corresponding ferritin level for female anemia (Hb: 12.0 g/dL) was 5.1 ng/mL, lower than the adequate level for hair growth (40-60 ng/mL), the corresponding Hb level of which was 13.1-13.8 g/dL.

Conclusion

The causes of FA varied, including nutrient deficiencies, autoimmune diseases, psychological stress, thyroid diseases, and COVID-19 vaccination, etc., Therefore, a complete survey before treatment is essential. Seventy percentage of FA cases were ID-FA. We suggest to redefine the serum ferritin level ≥60 ng/mL, with the corresponding Hb ≥13.0 g/dL as the normal range for early diagnosis. Initiation of iron supplementation within 6 months would result in a better prognosis.

The Effect of Smoking Habits on Blood Cadmium and Lead Levels in Residents Living Near a Mining and Smelting Area in Northwest China: a Cross-Sectional Study

Few studies have focused on environmental cadmium (Cd) and lead (Pb) exposure while exploring the effect of smoking on blood Cd (BCd) and blood Pb (BPb) levels. Moreover, essential trace elements affect the absorption, accumulation, and toxicity of Cd and Pb. To investigate the effect of smoking on BCd and BPb levels under high Cd and Pb exposure and the influence of essential trace elements on the effect, 301 residents living near a mining and smelting area in Northwest China were included in our study. After collecting health information and measuring BCd, BPb, serum iron, magnesium, and total calcium levels, we analyzed the association between smoking and BCd and BPb levels and the influence of the essential trace elements on the association. The results showed that BCd and BPb levels in smokers were significantly higher than those in non-smokers. There was a dose-response association between pack-years and the odds ratios (ORs) of high BCd and BPb levels in all participants compared with non-smokers. Serum iron, magnesium, and calcium had a negative effect on the elevations of the ORs of high BCd and BPb levels. In addition, smoking-related elevations of BCd and BPb levels vary by sex, age, BMI, and age of smoking initiation. Our findings present evidence for the effect of smoking on BCd and BPb levels under high Cd and Pb exposure and may provide guidance for the prevention and control of BCd and BPb elevations in residents living in Cd- and Pb-polluted areas.

Iron Status and Associated Factors among Canadian Women: Results from the Canadian Health Measures Survey

BACKGROUND

Iron deficiency and overload may negatively impact women's health. There has been limited assessment of iron status and its associated factors among Canadian women.

OBJECTIVES

This study investigated associations of various sociodemographic, lifestyle, medication, and dietary factors with body iron stores among pre- and postmenopausal women in Canada.

METHODS

Analyses were conducted using cross-sectional, nationally representative survey and biomarker data from women aged 20-79 y (n = 6362) in the Canadian Health Measures Survey (2009-2017). Body iron stores were assessed by measuring serum concentrations of ferritin (SF). Information on potential correlates was collected during an in-home interview. Multivariable linear regression analyses were performed to evaluate associations with SF concentration, and logistic regression was used to estimate associations with iron deficiency (SF <15 μg/L) or elevated iron stores (SF >150 μg/L).

RESULTS

Geometric mean SF concentrations were significantly higher in postmenopausal than in premenopausal women (73.2 versus 33.8 μg/L; P < 0.001). The prevalence of iron deficiency among pre- and postmenopausal women was 16.0% and 4.0%, respectively, whereas that of elevated iron stores was 2.7% and 21.0%, respectively. After simultaneous adjustment for multiple factors, including high-sensitivity CRP (inflammation marker), we found that age, East/Southeast Asian (versus White) race/ethnicity, alcohol, and red meat consumption were positively associated with SF concentration among pre- and postmenopausal women. In addition, aspirin use and dairy consumption were inversely associated with SF concentration among postmenopausal women only. Similar patterns were observed for associations with elevated iron stores among postmenopausal women, whereas higher grain consumption was associated with an increased prevalence of iron deficiency among premenopausal women.

CONCLUSIONS

Sociodemographic, lifestyle, medication, and dietary factors are correlated with iron status determined by SF concentration among Canadian women. The findings may have implications for intervention strategies aimed at optimizing body iron stores in pre- and postmenopausal women.

The clinical characteristics of anemia in native adults living at different altitudes of the Tibetan Plateau

To provide evidence-based medicine references for formulating prevention and control policies in plateau areas, we explore the characteristics of anemia patients in Tibet (the plateau areas of China), especially those located at an altitude above 4500 m. We collected clinical data from 379 Tibetan anemia patients over the age of 18 years. We found those female patients accounted for the majority of Tibetan anemia patients. Almost half of the anemia patients aged from 28 to 47 years. The percentage of severe anemia and extremely severe anemia was 45.4% and 2.4%, respectively. 88.7% of patients are engaged in agriculture and animal husbandry, and 81.5% of patients just graduated from primary school or below. The most common causes of anemia were nutritional anemia, especially iron-deficiency anemia. At high-altitude localities, folic acid-deficiency anemia needs more attention. Overall, this study showed that altitude influences the incidence, severity, and cause of anemia. Peasants and herdsmen, low education levels, young and middle-aged women, and nutrition status should be paid attention to in future anemia control.

Ferritin, transferrin, and transferrin receptor in relation to metabolic obesity phenotypes: Findings from the China Health and Nutrition Survey

Background

This study aimed to explore the relationship between iron markers and metabolic obesity phenotypes and the role of age.

Methods

Data were from the China Health and Nutrition Survey 2009. Metabolic obesity phenotypes included metabolically healthy with normal weight (MHNW), metabolically unhealthy with normal weight (MUNW), metabolically healthy with overweight/obesity (MHO), and metabolically unhealthy with overweight/obesity (MUO). Iron markers including ferritin, transferrin, and soluble transferrin receptor were calculated as Log and quartered. The linear regression and multinomial logistic regression were used to explore the association of iron markers with age and metabolic obesity phenotypes, respectively.

Results

Ferritin was linearly related with age, with β (95% confidence interval, CI) of 0.029 (0.027 to 0.032) and -0.005 (-0.007 to -0.002) for women and men. Transferrin was negatively associated with age in both men and women (β < -0.011). Furthermore, compared with participants in the quartile 1 ferritin group, those in the quartile 4 had increased odds of MUNW, MHO, and MUO, with odds ratio and 95% confidence interval (OR, 95% CI) of 3.06 (2.20 to 4.25), 1.66 (1.35 to 2.05), and 5.27 (4.17 to 6.66). Transferrin showed similar relationships with MUNW, MUO, and MHO; whereas transferrin receptor showed no significance. We also found joint associations of ferritin and transferrin with MUNW, MUO, and MHO. The interactive effect of ferritin and transferrin on MUO was significant (P = 0.015).

Conclusion

Increased ferritin and transferrin were associated with MUNW, MHO, and MUO. Age should be considered when investigating iron.

Factors associated with serum ferritin levels and iron excess: results from the EPIC-EurGast study

PURPOSE

Excess iron is involved in the development of non-communicable diseases such as cancer, type 2 diabetes and cardiovascular conditions. We aimed to describe the prevalence of excess iron and its determinants in healthy European adults.

METHODS

Sociodemographic, lifestyle, iron status, dietary information, and HFE genotyping were obtained from controls from the nested case-control study EPIC-EurGast study. High sensitivity C-reactive protein (hsCRP) was measured to address possible systemic inflammation. Descriptive and multivariate analyses were used to assess iron status and its determinants.

RESULTS

Out of the 828 participants (median age: 58.7 years), 43% were females. Median serum ferritin and prevalence of excess iron were 143.7 µg/L and 35.2% in males, respectively, and 77 µg/L and 20% in females, both increasing with latitude across Europe. Prevalence of HFE C282Y mutation was significantly higher in Northern and Central Europe (~ 11%) than in the South (5%). Overweight/obesity, age, and daily alcohol and heme iron intake were independent determinants for iron status, with sex differences even after excluding participants with hsCRP > 5 mg/L. Obese males showed a greater consumption of alcohol, total and red meat, and heme iron, compared with those normal weight.

CONCLUSION

Obesity, higher alcohol and heme iron consumption were the main risk factors for excess iron in males while only age was associated with iron overload in females. Weight control and promoting healthy lifestyle may help prevent iron overload, especially in obese people. Further research is needed to clarify determinants of excess iron in the healthy adult population, helping to reduce the associated comorbidities.

Association of Habitual Dietary Intake with Liver Iron-A Population-Based Imaging Study

Iron-related disorders of the liver can result in serious health conditions, such as liver cirrhosis. Evidence on the role of modifiable lifestyle factors like nutrition in liver iron storage is lacking. Thus, we aimed to assess the association of habitual diet with liver iron content (LIC). We investigated 303 participants from the population-based KORA-MRI study who underwent whole-body magnetic resonance imaging (MRI). Dietary habits were evaluated using repeated 24 h food lists and a food frequency questionnaire. Sex-stratified multiple linear regression models were applied to quantify the association between nutrition variables of interest and LIC, adjusting for liver fat content (LFC), energy intake, and age. Mean age of participants was 56.4 ± 9.0 years and 44.2% were female. Mean LIC was 1.23 ± 0.12 mg/g dry weight, with higher values in men than in women (1.26 ± 0.13 and 1.20 ± 0.10 mg/g, p < 0.001). Alcohol intake was positively associated with LIC (men: β = 1.94; women: β = 4.98, p-values < 0.03). Significant negative associations with LIC were found for fiber (β = −5.61, p < 0.001) and potassium (β = −0.058, p = 0.034) for female participants only. Furthermore, LIC was highly correlated with liver fat content in both sexes. Our findings suggests that there are sex-specific associations of habitual dietary intake and LIC. Alcohol, fiber, and potassium may play a considerable role in liver iron metabolism.

Trends and Urban-Rural Disparities of Energy Intake and Macronutrient Composition among Chinese Children: Findings from the China Health and Nutrition Survey (1991 to 2015)

The nutrition status of children is gaining more attention with a rapid nutrition transition. This study aimed to investigate trends and urban-rural differences in dietary energy and macronutrient composition among Chinese children. A total of 7565 participants aged 6 to 17 years were obtained from three rounds (1991, 2004 and 2015) of the Chinese Health and Nutrition Survey (CHNS). The individual diet was evaluated via three consecutive 24-hour dietary recalls and compared with the Chinese Dietary Reference Intakes (DRIs). From 1991 to 2015, there was a significant increase in children’s fat intake, the proportion of energy intake from fat, and the proportion of children with more than 30% of energy from fat and less than 50% of energy from carbohydrates (p < 0.001). Compared with the DRI, the proportion with higher fat and lower carbohydrate intakes were, respectively, 64.7% and 46.8% in 2015. The urban-rural disparities in fat and carbohydrate intake gradually narrowed, while the gap in protein intake increased notably over time (p < 0.001). Chinese children experienced a rapid transformation to a low-carbohydrate and high-fat diet. Urban-rural disparities persistently existed; further nutritional interventions and education were of great significance, so as to ensure a more balanced diet for Chinese children.

Prevalence and health correlates of anaemia among community-dwelling Chinese older adults: the China Health and Retirement Longitudinal Study

OBJECTIVES

To identify the prevalence of anaemia among older adults in China by sociodemographic and geographical regions, and cross-sectionally examine the associations between anaemia and several geriatric outcomes.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

Participants were 6656 older adults aged at least 60 years with haemoglobin data from the 2015 to 2016 wave of the China Health and Retirement Longitudinal Study.

METHODS

We examined the prevalence of anaemia by sociodemographics (age, sex, residence, education, marital status) and geographical regions, adjusting for age. We investigated the associations between anaemia and geriatric conditions.

RESULTS

The prevalence of anaemia was 20.6% among adults ≥60 years and was higher at advanced ages, among those who were females, living in rural areas, and those who were unmarried. The southern region of China had a higher burden of anaemia than the north. Anaemic adults had a higher age-adjusted prevalence of falls, activities of daily living (ADL) disability, instrumental ADL disability, lower extremely functional limitation, upper extremely functional limitation, low gait speed, low grip strength and low self-reported memory.

CONCLUSIONS

Anaemia affected approximately one in five older adults in China, particularly in those with disadvantaged sociodemographics, and anaemia was associated with a higher burden of geriatric conditions. Huge geographical disparities of anaemia prevalence between northern and southern regions reflected the dietary variations in different regions. Efforts on preventing anaemia and reducing regional disparities of anaemia were needed to improve older adults' health in China.

Validity and reliability of a simplified food frequency questionnaire: a cross sectional study among physical health examination adults in southwest region of China

Background

In China, many people are regarded suitable for participating in regular physical examination for diagnosis and prevention of diseases. Some simplified food frequency questionnaires have been designed and used; however, the accuracy of the questionnaire is absent. This study aimed to examine the reliability and validity of simplified food frequency questionnaire (SFFQ) used among adults undergoing physical examination in southwest region of China.

Methods

This was a cross-sectional study conducted among physical health examination adults in the Southwest region of China. A total of 239 participants aged 20–65 were included from February 2019 to June 2019. The performance of SFFQ was evaluated by means of a three-day 24-h dietary record (3R24). The relative validity and agreement was assessed by Pearson’s correlation and intra-class correlation coefficients (ICC), respectively.

Results

The median energy-adjusted ICC of food groups between SFFQ2 and SFFQ1 was 0.59 (range: 0.49–0.73) and the ICC of nutrients was 0.47(range: 0.39–0.76). The Pearson correlation showed a valid comparisons between SFFQ1 and 3R24, ranging from -0.086 to 0.93 for food and 0.21 to 0.71 for nutrition, respectively. The energy-adjustment slightly increased the correlation coefficients.

Conclusions

The reliability and validity of SFFQ was acceptable, and it could be an appropriate dietary assessment tool for the future epidemiological studies conducted among physical health examination adults of southwest China.

Trial registration

CHiCTR, ChiCTR1900020934, Registered 22 January 2019, https://www.chictr.org.cn/edit.aspx?pid=35414&htm=4.

Gender differences in the relationship between dietary energy and macronutrients intake and body weight outcomes in Chinese adults

BACKGROUND

To explore the gender differences in the relationship between dietary energy and macronutrients intake and body weight outcomes in Chinese adults.

METHODS

Data from the China Health and Nutrition Survey (CHNS, 2015) for10,898 participants aged 18-64 years. Three consecutive 24-h dietary recalls was used to assess the dietary intake. Quantile regression models for body mass index (BMI) and waist circumference (WC) were performed separately for each sex.

RESULTS

Adult males showed greater absolute intakes of energy and macronutrients as compared to females as per the body weight outcomes. A 10% increase in BMI resulted in an additional intake of 0.002-0.004 kcal/d of dietary energy, 0.032-0.057 g/d of fats, 0.039-0.084 g/d of proteins, and 0.018-0.028 g/d of carbohydrates across all quantiles in males (p <  0.05). A 10% increase in WC lead to an additional intake of 0.004-0.008 kcal/d of dietary energy, 0.051-0.052 g/d of carbohydrates across the entire quantile in males (p <  0.05), and an increased intake of 0.060-0.150 kcal/d of fat in females (p <  0.05).

CONCLUSIONS

Dietary fat intake could be the risk factor of abdominal obesity in women. The importance of gender-specific evidence should be considered before promoting macronutrient allocation for the prevention and treatment of obesity.

Association between Hemoglobin Levels and Colorectal Polyps in Asymptomatic Chinese Adults

Methods

A cross-sectional analysis was performed among 1633 asymptomatic adults who underwent colonoscopy examinations during routine health check-ups at the First Affiliated Hospital, College of Medicine, Zhejiang University, between 2015 and 2018.

Results

A total of 449 (27.50%) participants were diagnosed with colorectal polyps, and those with colorectal polyps had significantly higher hemoglobin levels than did those without colorectal polyps. Hemoglobin levels were positively associated with the prevalence of colorectal polyps, with rates of 16.43%, 26.20%, 32.17%, and 35.87% among participants with hemoglobin levels in the first, second, third, and fourth quartiles, respectively (P for trend < 0.001). Stepwise multiple regression analysis showed that elevated hemoglobin levels independently increased the risk of colorectal polyps (odd ratio = 1.017; 95% confidence interval: 1.008–1.026).

Conclusion

Elevated hemoglobin levels were significantly and independently associated with the prevalence and risk of colorectal polyps in asymptomatic adults.

Meat and fish intake and type 2 diabetes: Dose-response meta-analysis of prospective cohort studies

AIMS

This meta-analysis aimed to quantitatively examine the possible associations between total meat, red meat, processed meat, poultry and fish intakes and type 2 diabetes (T2D).

METHODS

Relevant articles were identified in PubMed, Embase and Web of Science databases using a search time up to January 2019. Generalized least-squares trend estimations and restricted cubic spline regression models were used for analysis.

RESULTS

Twenty-eight articles were included in the analysis. When comparing the highest with the lowest category of meat intake, the summary relative risk of T2D was 1.33 (95% CI: 1.16-1.52) for total meat, 1.22 (95% CI: 1.16-1.28) for red meat, 1.25 (95% CI: 1.13-1.37) for processed meat, 1.00 (95% CI: 0.93-1.07) for poultry and 1.01 (95% CI: 0.93-1.10) for fish. In the dose-response analysis, each additional 100g/day of total and red meat, and 50g/day of processed meat, were found to be associated with a 36% (95% CI: 1.23-1.49), 31% (95% CI: 1.19-1.45) and 46% (95% CI: 1.26-1.69) increased risk of T2D, respectively. In addition, there was evidence of a non-linear dose-response association between processed meat and T2D (P=0.004), with the risk increasing by 30% with increasing intakes up to 30g/day.

CONCLUSION

Our meta-analysis has shown a linear dose-response relationship between total meat, red meat and processed meat intakes and T2D risk. In addition, a non-linear relationship of intake of processed meat with risk of T2D was detected.

Association Between Iron Status and Risk of Chronic Kidney Disease in Chinese Adults

Background: Even though it is well-known that iron deficiency is the result of chronic kidney disease (CKD), whether iron will affect kidney function and disease in the general population is not clear. We thus conducted a nationwide cross-sectional study using data from the China Health and Nutrition Survey (CHNS) to assess the relationship of iron status with estimated glomerular filtration rate (eGFR) and CKD among general adults. Methods: A total of 8,339 adults from the China Health and Nutrition Survey in the wave of 2009 were included to assess the association between iron status and eGFR/CKD. Serum ferritin (SF), transferrin, soluble transferrin receptor (sTfR), and hemoglobin (Hb) were measured. The relationship of iron status and eGFR was evaluated by using multi-variable linear regression model. The effect of iron status on the odds of CKD was calculated by logistic regression model. Results: For the association between iron status and eGFR, every 100 μg/L increase in SF was correlated with 0.26 ml/min per 1.73 m2 (95% CI: 0.08-0.44) decrease in eGFR, and every 5 mg/L increase in sTfR was associated with a decrease of 6.00 ml/min per 1.73 m2 (95% CI: 3.79-8.21) in eGFR. There were no significant associations between Hb or transferrin with eGFR. For the association between iron status and CKD, every 5 g/L increase in sTfR was associated with an odds ratio of 3.72 (95% CI: 2.16-6.13) for CKD. The concentrations of Hb were associated with the odds of CKD in a U-shaped manner, with the lowest risk in the Hb range of 136-141 g/L. There was a positive correlation between SF concentration and CKD prevalence but not in a dose-response manner. The odds of CKD for participants in the highest tertile increased by 28% (98% CI: 1-63%) compared with those in the lowest tertile. Conclusion: The concentration of SF and sTfR was positively correlated with the odds of CKD, and Hb was associated with the odds of CKD in a U-shaped manner. Further large prospective researches are warranted to confirm these findings.

Markers of iron status, blood pressure and incident hypertension among Chinese adults

BACKGROUND AND AIMS

The evidence on the relationship between markers of iron, blood pressure and hypertension are limited and inconsistent. This prospective cohort study aimed to investigate the relationship of serum ferritin (SF), transferrin, soluble transferrin receptor (sTFR) and haemoglobin on blood pressure and incident hypertension in the China Health and Nutrition Survey (CHNS) study.

METHODS AND RESULTS

We studied 8337 adults aged 18 years old or above from CHNS in 2009 to investigate the association of markers of iron and blood pressure (BP). Among them, 4509 non-hypertensive participants who completed follow up were included to investigate the association of markers of iron and hypertension development. Linear regression model was used to assess the association between markers of iron and BP. Cox regression model was used to examine the association of markers of iron and hypertension development. SF and serum sTFR concentration had a non-significant effect on incident hypertension. Transferrin and haemoglobin concentrations were positively associated with incident hypertension. Compared to the participants with the lowest tertile of transferrin, those with the highest tertile had a higher risk of developing hypertension [HR: 1.26, 95% CI (1.04, 1.53), P = 0.017]. Similarly, participants with the highest tertile of haemoglobin had a significantly higher risk of incident hypertension [HR: 1.27, 95% CI (1.01, 1.59), P = 0.038].

CONCLUSION

The current study found that haemoglobin and transferrin levels were positively associated with blood pressure and incident hypertension. Further research in different ethnic groups is required to confirm the association of the full range of markers of iron with BP and incident hypertension.

Iron insufficiency among young Australian women: a population-based survey

BACKGROUND

Although serum ferritin is considered a reliable indicator of iron stores, there are few data documenting the prevalence of low ferritin in representative samples of young women.

AIMS

To estimate the prevalence of low ferritin and to identify factors associated with low ferritin in young Australian women.

METHODS

Women, aged 18-39 years, living in the eastern states of Australia were recruited by email to a cross-sectional, online questionnaire-based study between November 2016 and July 2017. Participants not pregnant, breast feeding, taking hormonal contraception, using assisted reproduction or postmenopausal were invited to provide a blood sample.

RESULTS

Of the 3689 invited participants, 761 (23.1%) provided a sample and 736 women, mean (SD) age 31.7 (±5.6) years, were included in the analyses. The overall prevalence of serum ferritin <30 μg/L was 34.8% (95% confidence interval (CI) 31.4-38.3%), with 41.4% (35.1-48.0%) in NSW, 31.5% (26.4-37.1%) in Victoria and 32.6% (26.8-39.0%) in Queensland. Serum ferritin <30 μg/L was positively associated with the reporting of >2 days of heavy menstrual bleeding (adjusted odds ratio (AOR) 1.73, 95% CI 1.15-2.59), living in New South Wales (AOR 1.57, 95% CI 1.07-2.30), not working outside home (AOR 1.58, 95% CI 1.01-2.49), and inversely associated with never experiencing heavy menses (AOR 0.46, 95% CI 0.23-0.93) and obesity (AOR 0.32, 95% CI 0.21-0.50).

CONCLUSIONS

This study demonstrates that serum ferritin below 30 μg/L is common amongst young Australian women. Healthcare professionals should note the association between low ferritin and heavy bleeding.

Markers of Iron Status Are Associated with Risk of Hyperuricemia among Chinese Adults: Nationwide Population-Based Study

Background: Elevated serum uric acid (SUA) involved in iron metabolism, has been increasingly recognized as a risk factor for gout and cardiovascular diseases. The objective of this study was to examine the associations between markers of iron status with risk of hyperuricemia (HU) in Chinese adult population. Methods: Data were extracted from the 2009 wave of the China Health and Nutrition Survey, consisting of 7946 apparently healthy adults. Serum ferritin (SF), transferrin, soluble transferrin receptors (sTfR), hemoglobin (Hb), high-sensitivity C-reactive protein (hs-CRP), and SUA were measured. Diet was assessed with three consecutive 24 h recalls. Demographic characteristics, smoking status, alcohol consumption, and physical activities were investigated using a structured questionnaire. Multilevel mixed-effects models were constructed to estimate the associations of SF, transferrin, sTfR, and Hb with SUA and the risk of HU. Results: The crude prevalence of HU was 16.1%. SF, transferrin, and Hb levels were positively associated with SUA and the risk of HU after adjustment for cluster effects and potential confounders (all p-trend < 0.05). Compared with participants in the lowest quartile of SF, those in the highest quartile had significantly higher SUA concentrations (β = 0.899 mg/dL, 95% confidence interval (CI): 0.788, 1.010; p < 0.001) and higher risk of HU (odds ratio (OR) = 3.086, 95% CI: 2.450, 3.888; p < 0.001). Participants with the highest quartile of transferrin had significantly higher SUA concentrations (β = 0.488 mg/dL, 95% CI: 0.389, 0.587; p < 0.001) and higher risk of HU (OR: 1.900; 95% CI: 1.579, 2.286; p < 0.001) when compared with those with the lowest quartile. In male participants, those in the highest quartile of Hb had significantly higher risk of HU when compared to the reference group (OR: 1.401, 95% CI: 1.104, 1.777; p < 0.01); however, this association was not found in female participants (OR: 1.093; 95% CI: 0.821, 1.455; p = 0.544). Conclusion: SF, transferrin, and Hb levels were positively associated with the risk of HU, and additional studies are needed to confirm the findings, as well as to elucidate their underlying mechanisms.