Contributions and Implications of the Tehran Lipid and Glucose Study

Is variety more important than quantity of fruits and vegetables in relation to cardiovascular disease incidence and mortality? Results from a prospective cohort study

We aimed to prospectively assess the association between variety and quantity of fruits and vegetables (FV) and cardiovascular diseases (CVD) incidence and mortality due to the limited evidence. Our analysis included 2,918 adults with a follow-up period of 29,559 person-years. An inverse association was detected between fruit intake and the risk of incidence and mortality from CVD. We found no association between diversity scores of fruits, vegetables, and FV with CVD risk. Subjects with high quantity-high variety, high quantity-low variety, and low quantity-high variety of fruits, vegetables, or FV exhibited no difference in CVD risk compared to the subjects with low quantity-low variety intake. Increasing the variety of FV was associated with increases in the intake of β-carotene, lycopene, lutein, vitamin C, selenium, fibre, fat, and protein after adjustment for the quantity and covariates. We detected an inverse association between fruit intake and the incidence and mortality rates of CVD.

Usual intake of dairy products and the chance of pre-diabetes regression to normal glycemia or progression to type 2 diabetes: a 9-year follow-up

BACKGROUND

We assessed the possible effect of usual dairy consumption on pre-diabetes (Pre-DM) remission or progression to type 2 diabetes (T2D).

METHODS

Pre-DM adults (n = 334, mean age of 49.4 years, and 51.5% men) were assessed for dairy intakes (2006-2008) and followed up to 9 years for incidence of T2D or normal glycemia (NG). All biochemical measurements were done at baseline and all subsequent examinations with 3-y follow-up intervals. Multinomial regression models with adjustment of confounding variables were used to estimate odds ratios (OR) and 95% confidence intervals (CIs) of incident T2D and NG for each serving/d dairy consumption.

RESULTS

The odds of NG was significantly elevated by 69% (OR = 1.69, 95% CI = 1.00-2.86, P = 0.05) per 200 g/d increased high-fat dairy intake, while the amount of total dairy or low-fat dairy was not related to the outcomes. Higher intakes of yogurt were more likely to be associated with an increased odds of NG (OR = 1.82, 95% CI = 1.20-2.74, P = 0.01). Usual intakes of milk, cheese, or cream-butter were not associated to Pre-DM remission or progression to T2D.

CONCLUSION

Regular dairy consumption may increase the chance of Pre-DM regression to NG.

The association of ideal cardiovascular health metrics and incident hypertension among an urban population of Iran: a decade follow-up in Tehran Lipid and Glucose Study

We aimed to determine the association between ideal cardiovascular health metrics (ICVHM) and the incidence of hypertension among Iranian adults. The study population included 5409 Iranian adults aged ≥20 years (2088 men) without hypertension (applying the 2017 American College of Cardiology (ACC)/American Heart Association (AHA) guideline) at baseline. The ICVHM was defined according to the AHA's 2020 impact goals, excluding total cholesterol was replaced by non-HDL cholesterol (non-HDL-C). Multivariable Cox proportional hazards regression analysis was done to estimate the hazard ratios (HRs) for ICVHM both as continuous and categorical variables. During a median 8.5-year follow-up, 2972 new cases of hypertension were identified (men: 1,287). Non-HDL-C < 130 mg/dL in men [HR (95% CI): 0.75(0.65-0.86)] and fasting plasma glucose(FPG) < 100 mg/dL in women[HR (95% CI): 0.79(0.64-0.97)], and among both genders, being normal/overweigth status (compared to obese) and blood pressure <120/80 mmHg were associated with a lower risk for hypertension. Additionally, in both gender, a 1-point increase in the number of global ICVHM decreased the risk of hypertension by more than 10%, and having ≥5 vs. <2 ICVHM, were associated with a lower risk of hypertension by 30% (all p values < 0.05). Applying the JNC 7 guideline, the association between ICVHM, with incident hypertension, were generally similar. Having a higher number of ICVHM was associated with a lower risk of incident hypertension, using both 2017 ACC/AHA and JNC 7 guidelines, mostly attributable to keeping the ideal status of body mass index, non-HDL-C, and FPG.

The association between metabolic syndrome and insulin resistance with risk of cardiovascular events in different states of cardiovascular health status

AIMS/INTRODUCTION

The aim was to examine the joint effect of metabolic syndrome (MetS) and insulin resistance (IR) with ideal cardiovascular health (iCVH) status on incident cardiovascular diseases (CVDs).

MATERIALS AND METHODS

The study included 6,240 Iranian adults ≥30 years, free of prior cardiovascular disease. Ideal cardiovascular health was determined based on American Heart Association's Life Simple 7. Metabolic syndrome was defined according to the Joint Interim Statement Criteria, and insulin resistance was defined as HOMA-IR ≥1.85 in women and ≥2.17 in men. Multivariable Cox proportional hazard ratios (HRs) were applied to examine the impact of metabolic syndrome, and insulin resistance at various levels of iCVH status.

RESULTS

During the median follow-up of 14.0 years, 909 cases of cardiovascular disease occurred. Metabolic syndrome and insulin resistance were significantly associated with incident cardiovascular disease events. In the poor and intermediate status, metabolic syndrome increased cardiovascular disease events with HRs of 1.83 and 1.57, respectively; the corresponding values for insulin resistance in the mentioned categories were 1.91 and 1.25, respectively (P values < 0.05). In the intermediate and poor iCVH status, hypertriglyceridemia was linked to a 40% and 35% higher risk of cardiovascular disease, the corresponding values for low HDL-C was 20% and 60%, respectively (P values < 0.05). Although adding metabolic syndrome, its dyslipidemia and insulin resistance to iCVH status in both poor and intermediate status significantly improve the prediction of cardiovascular disease using net reclassification improvement (P values < 0.05), the value of C-index did not change.

CONCLUSIONS

Metabolic syndrome and the dyslipidemia component had a negligible but significant improvement in the prediction of cardiovascular disease among individuals with non-optimal iCVH status.

The effect of smoking on latent hazard classes of metabolic syndrome using latent class causal analysis method in the Iranian population

BACKGROUND

The prevalence of metabolic syndrome is increasing worldwide. Clinical guidelines consider metabolic syndrome as an all or none medical condition. One proposed method for classifying metabolic syndrome is latent class analysis (LCA). One approach to causal inference in LCA is using propensity score (PS) methods. The aim of this study was to investigate the causal effect of smoking on latent hazard classes of metabolic syndrome using the method of latent class causal analysis.

METHODS

In this study, we used data from the Tehran Lipid and Glucose Cohort Study (TLGS). 4857 participants aged over 20 years with complete information on exposure (smoking) and confounders in the third phase (2005-2008) were included. Metabolic syndrome was evaluated as outcome and latent variable in LCA in the data of the fifth phase (2014-2015). The step-by-step procedure for conducting causal inference in LCA included: (1) PS estimation and evaluation of overlap, (2) calculation of inverse probability-of-treatment weighting (IPTW), (3) PS matching, (4) evaluating balance of confounding variables between exposure groups, and (5) conducting LCA using the weighted or matched data set.

RESULTS

Based on the results of IPTW which compared the low, medium and high risk classes of metabolic syndrome (compared to a class without metabolic syndrome), no association was found between smoking and the metabolic syndrome latent classes. PS matching which compared low and moderate risk classes compared to class without metabolic syndrome, showed that smoking increases the probability of being in the low-risk class of metabolic syndrome (OR: 2.19; 95% CI: 1.32, 3.63). In the unadjusted analysis, smoking increased the chances of being in the low-risk (OR: 1.45; 95% CI: 1.01, 2.08) and moderate-risk (OR: 1.68; 95% CI: 1.18, 2.40) classes of metabolic syndrome compared to the class without metabolic syndrome.

CONCLUSIONS

Based on the results, the causal effect of smoking on latent hazard classes of metabolic syndrome can be different based on the type of PS method. In adjusted analysis, no relationship was observed between smoking and moderate-risk and high-risk classes of metabolic syndrome.

Adherence to a modified nordic diet and the risk of cardiovascular events in a non-nordic population: a prospective cohort study

BACKGROUND

Even though studies have demonstrated that the Nordic diet is beneficial for cardiovascular disease (CVD) risk factors, it is unknown if this diet is associated with actual CVD cases. So, the aim of this study was to investigate the association between a modified Nordic diet and the risk of CVD in non-Nordic adults.

METHODS

In this cohort study, 2918 people who participated in the third phase of the Tehran Lipid and Glucose Study (TLGS) were examined. All participants had no CVD at the beginning of the study, which was monitored until 2018. The Nordic score was calculated using a validated food frequency questionnaire (FFQ). Patients' medical records were examined for cardiovascular events such as coronary heart disease (CHD), stroke, and mortality from CVD. The Cox proportional hazards model was used to assess the relationship between the Nordic score and the risk of CVD.

RESULTS

During a median follow-up of 10.6 years, 203 subjects experienced cardiovascular events. The third and fourth quartiles of the Nordic score were associated with a 35% (HR: 0.65; 95% CI: 0.45, 0.95) and 60% (HR: 0.40; 95% CI: 0.27 to 0.65) reduced risk of CVD compared to the lowest quartile. Subgroup analyses revealed that a high Nordic score was inversely associated with a lower risk of CVD in adults older than 45 years of age, both sexes, and all BMI categories. Each 1-score increase in cereal consumption was associated with a 24% (HR: 0.76; 95% CI: 0.67 to 0.87) lower risk of CVD; low-fat milk with a 23% (HR: 0.77; 95% CI: 0.68 to 0.87); and fish with a 22% (HR: 0.78; 95% CI: 0.69 to 0.89) lower risk of CVD.

CONCLUSION

We found that high Nordic score adherence may prevent cardiovascular events in non-Nordic populations. Cereals, fish, and low-fat milk were the primary components of the Nordic diet that indicated an inverse relationship with CVD.

Health-related quality of life in women with various levels of spiritual health

This study investigates for the first time the relationship between spiritual health (SH) and health-related quality of life (HRQoL) in different periods of life in healthy women, which could be important in the current critical post-pandemic situation. We recruited data from 2238 healthy women in the Tehran Lipid and Glucose Study (TLGS) framework, performed a cross-sectional study, and divided them into four age groups: 1) 20-34, 2) 35-44, 3) 45-54, and 4) 55≤ years. HRQoL and SH were measured using Short-Form 12-Item Health Survey version 2 and spiritual health inventory in Muslim adults (SHIMA-48). We defined low and high SH as the first and third tertile of SHIMA-48 scores. Most participants were in the first age group (39 percent), were married (74.7 percent), and were housewives (74.7 percent). The mean mental component summary score and its domains were directly associated with age. This subscale was significantly higher in individuals with high SH scores in all age groups. However, except for general health, other physical subscales did not differ significantly between the two levels of SH among the age groups studied. Results indicate higher HRQoL, especially mental health, in healthy women with increased spiritual well-being. This finding can be used in programs to improve psychological health in women.

Gender differences in the impact of 3-year status changes of metabolic syndrome and its components on incident type 2 diabetes mellitus: a decade of follow-up in the Tehran Lipid and Glucose Study

Background

The aim of this study was to examine the gender differences in the association between status changes of metabolic syndrome (MetS) and its components, using Joint Interim Statement (JIS) criteria, with the risk of type 2 diabetes mellitus (T2DM) among an urban population.

Methods

The study included 4,463 Iranian adult participants (2,549 women) aged ≥20 years. Based on status changes of MetS and its components during 3 years, subjects were categorized into four groups: MetS-free (reference), MetS-developed, MetS-recovery, and MetS-stable. A similar categorization was applied to MetS components. Multivariable Cox regression models were used for estimating hazard ratios (HRs) and women-to-men ratios of HRs (RHRs).

Results

During a median follow-up of 9.3 years, 625 T2DM events (351 women) occurred. Compared with the reference, the HRs of the MetS-developed, -recovery, and -stable groups among men for incident T2DM were 2.90, 2.60, and 4.92; the corresponding values for women were 2.73, 2.88, and 5.21, respectively (all p-values < 0.01), without significant gender difference in these relationships. In both genders, the fasting plasma glucose (FPG) component, regardless of the change in status, was strongly and significantly associated with incident T2DM with HRs ranging from 2.49 to 9.42; a similar association was also found for high waist circumference (WC)-recovery and -stable groups, with HRs ranging from 1.58 to 2.85 (p-values ≤ 0.05). Regarding gender differences, the development and persistence of high blood pressure (BP) status exposed men to greater T2DM risk than women with women-to-men RHRs of 0.43 (0.26-0.72) and 0.58 (0.39-0.86), respectively. Moreover, stable low levels of high-density lipoprotein cholesterol (HDL-C) and high triglyceride (TG) levels conferred higher T2DM risk in women than in men, with women-to-men RHRs of 1.67 (0.98-2.86) and 1.44 (0.98-2.14), respectively (both p-values = 0.06).

Conclusion

Among Tehranian adults, in both genders, all status changes of MetS, even those recovered from MetS, have a higher risk of T2DM compared to those who never had MetS. Also, all statuses of high FPG, in addition to recovered and stable high WC, were strongly associated with T2DM risk. Specifically, men with stable or developed high BP and women with stable dyslipidemic status were at differentially increased risk of incident T2DM.

Dietary sodium to potassium ratio is an independent predictor of cardiovascular events: a longitudinal follow-up study

BACKGROUND

The current prospective cohort study aimed to explore the potential associations between dietary sodium (Na), potassium (K), and sodium-to-potassium (Na-to-K) ratio with an incidence risk of cardiovascular disease (CVD) among Iranian adults.

METHODS

The participants of the Tehran Lipid and Glucose Study (men and women aged 30-84 years, n = 2050), free of CVD at baseline (2006-2008) were included. Dietary intakes were assessed using a validated food frequency questionnaire (FFQ), and incident CVD (i.e., coronary heart disease, stroke, and CVD mortality) were documented up to March 2018. Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence interval (CI) regarding the association between dietary Na, K, and Na-to-K ratio with CVD events.

RESULTS

During a median follow-up of 10.6 years, 10.14% of participants experienced CVD outcomes. A 41% increased risk of CVD in relation to each increase in 1000 mg/d of Na intake. In the fully-adjusted model, higher Na intake (> 4143 versus < 3049 mg/d) was significantly related to the increased risk of CVD (HR = 1.99, 95% CI = 1.06-3.74). Independent of the well-known risk factors, a 56% reduced risk of CVD was observed in the participants with a higher dietary K intake (HR = 0.44, 95% CI = 0.20-0.94). A Higher Na-to-K ratio was associated with an increased risk of CVD (HR = 1.99, 95% CI = 1.13-3.52).

CONCLUSION

Our study showed that the Na-to-K ratio might independently predict future risk of CVD events in adults.

Gender-specific effect of outdoor temperature and seasonal variation on blood pressure components: a cross-sectional study on Iranian adults from 2015 to 2018

Blood pressure (BP) is influenced by both individual and environmental factors such as ambient temperature. However, the gender-stratified and component-specific impact of temperature on BP is not well understood. Herein, we examined the temperature and seasonal effects on four main BP components, namely systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and pulse pressure (PP), in both genders. A total of 8990 (3954 men) Tehranian adults during 2015-2018 were included. Linear regression models for analyzing data in three models including unadjusted, age-adjusted, and further adjusted for known sociodemographic and cardiovascular confounders were conducted. Among women, each 10 °C increment was associated with a significant decrease of - 0.48 mmHg (95% confidence interval (CI): - 0.86, - 0.19) and - 0.65 mmHg (- 0.76, - 0.41) in SBP and MAP, respectively. In men, the corresponding value for SBP was - 0.46 (- 0.82, - 0.16) mmHg (P = 0.058). Gender-specific analysis in each season showed that among women, PP increased in autumn and winter with each 10 °C decrease (P < 0.05). The mean increase in SBP (3.4 and 2.06 mmHg in women and men, respectively), DBP (1.66 and 1.19 mmHg), and MAP (2.71 and 1.12 mmHg) was observed during winter compared to summer (all P < 0.05). PP showed seasonality only in women (1.46 mmHg, P-value = 0.003). In both genders, SBP in age > 60 years was more susceptible to variation compared to younger ages. Furthermore, obese women had more SBP changes compared to their non-obese counterparts (all P for interaction < 0.05). In conclusion, there was a sex difference in BP response to the outdoor temperature, with higher vulnerability among women. The reverse relation between temperature and BP occurred particularly among elderly and obese individuals. Careful monitoring of BP in cold seasons, specifically in the mentioned subgroups, could potentially attenuate cardiovascular risks.

Longitudinal Associations Between TPO Gene Variants and Thyroid Peroxidase Antibody Seroconversion in a Population-Based Study: Tehran Thyroid Study

Introduction: Autoimmune thyroid diseases (AITD) are usually accompanied by anti-thyroid antibodies which can serve as early predictive markers. This study was designed to investigate the relationship between thyroid peroxidase (TPO) gene variants and the presence of TPOAb and to evaluate the effect of environmental factors associated with seroconversion from TPOAb-negative to TPOAb-positive. Methods: Participants from phases 1 and 2 of the Tehran Thyroid Study in (n = 5327, ≥20 years) were evaluated in terms of TPOAb positivity, and its relationship with 53 single nucleotide polymorphisms (SNPs) from within the TPO gene (cross-sectional approach). TPOAb-negative participants (n = 4815) were followed up for seroconversion for 5.5 years. The relationship between the TPO gene variants and the TPOAb seroconversion was evaluated (longitudinal approach). Results: There were 521 TPOAb-positive participants in the cross-sectional phase and 266 new TPOAb-positive cases observed during the follow-up period. After quality control (Hardy-Weinberg equilibrium (p < 1 × 10^-5) and minor allele frequency < 0.05), 49 SNPs were qualified for association analyses. From this set fourteen SNPs were identified that were associated with TPOAb positivity. rs6605278, located in the 3'UTR TPO gene, was the most highly significantly associated of the variant and remained associated after adjustment for age, gender, body mass index (BMI), smoking, number of parity, and oral contraceptive consumption in both cross-sectional and longitudinal analyses (p < 0.05). Conclusions: TPOAb-positivity can be partially explained by variants in the TPO gene. New TPOAb-associated SNPs were observed in Iranians as an ethnically diverse population.

The Mediterranean, DASH, and MIND diets and the incident of hypertension over a median follow-up of 7.4 years in the Tehran Lipid and Glucose Study

BACKGROUND

Despite the favorable effects of well-known dietary patterns in the treatment of hypertension (HTN), such as the Mediterranean (MED) and Dietary Approach to Stop Hypertension (DASH) diets, it is uncertain if adherence to these diets can reduce the risk of HTN, especially in non-Mediterranean populations. Moreover, none of the previous studies evaluated the association between the MED-DASH Intervention for Neurodegenerative Delay (MIND) diet adherence and the incidence of HTN. Therefore, we aimed to assess the association of adherence to these diets with the development of HTN in adults.

METHODS

This prospective study included 2706 adults free of HTN who were selected from the Tehran Lipid and Glucose Study. The MED, DASH, and MIND diet scores were computed at baseline using dietary information collected with the food frequency questionnaire. Associations between the dietary indices and risk of HTN over a median follow-up of 7.4 years were examined using Cox proportional hazards regression analysis.

RESULTS

The baseline mean age of participants was 37.9 ± 12.5 years (age range: 20-79 years), and 52.4% were women. During the 18262 person-years follow-up, 599 incidents of HTN were identified. There was no significant relationship between the dietary scores and the risk of HTN, either as continuous or categorical variables, even after excluding individuals with early/late HTN diagnosis, prehypertension, diabetes, or chronic kidney disease at baseline. A significant interaction was found between body mass index (BMI) and DASH (P-interaction < 0.001). Stratified analyses based on baseline BMI status revealed an inverse association between DASH and HTN risk in individuals with normal-weight (HR = 0.84, 95% CI = 0.71-0.98, P = 0.031), although this association did not reach statistical significance across the tertiles of DASH.

CONCLUSIONS

In this study, MED, DASH, and MIND showed no significant association with the occurrence of HTN in adults. Further prospective studies on diverse populations are required to assess whether adherence to the MED, DASH, and MIND diets is an effective strategy for reducing the occurrence HTN.

Dietary oxalate-calcium balance and the incidence of hypertension and chronic kidney disease: a prospective study among an Asian population

Background

The potential effects of dietary oxalate (Ox) intake on cardio-renal function have remained unestablished. We evaluated the effect of usual Ox intake and its interaction with dietary calcium (Ca) on incident hypertension (HTN) and chronic kidney disease (CKD).

Methods

Adult men and women, free of HTN and CKD at baseline (2006–2008), were recruited. Dietary intakes were assessed using a validated food frequency questionnaire, and the outcomes were documented up to 2014–2017. Multivariate Cox proportional hazard regression models were used to estimate the development of HTN and CKD in relation to Ox intakes. Repeated-measures generalized estimating equation (GEE) linear regression models were used to assess possible effect of Ox-intake on the estimated glomerular filtration rate (eGFR) and blood pressure levels over eight years.

Results

Dietary Ox intakes were positively associated with incident CKD (HR = 2.59, 95% CI = 1.46–4.64) and HTN (HR = 1.79, 95% CI = 1.05–3.04). Compared to high-Ca consumers, subjects who had lower Ca intakes (< 990 vs. 1580 mg/d) had a higher incidence of CKD and HTN (HR = 2.43, 95% CI = 1.06–5.55, and HR = 1.72, 95% CI = 0.76–3.78). Participants with higher intakes of Ox (> 220 vs. < 150 mg/d) had lower eGFR values (75.3, 95% CI = 75.0–76.5 vs. 77.3, 95% CI = 76.6–78.1 mL/min/1.73m², P_time×group = 0.004) and higher SBP levels (112, 95% CI = 111–113 vs. 109, 95% CI = 108–110 mmHg, P_time×group = 0.007) overtime.

Conclusion

Higher dietary Ox intake may increase the risk of HTN and CKD. The relation between dietary Ox and risk of HTN and CKD seems to be varied by Ca intake, and subjects with lower Ca intakes may be more burdened by excessive amounts of dietary Ox.

Effectiveness of a practical multi-setting lifestyle intervention on the main BMI trajectories from childhood to young adulthood: A community-based trial

Background

Preventing overweight in childhood and subsequent stages of life is still a global challenge. Despite numerous relevant lifestyle interventions, data on their impact on different BMI change pathways over time is rare. The present study aimed to investigate the effect of a multi-setting lifestyle intervention on BMI trajectories from childhood to young adulthood.

Methods

A multi-setting lifestyle intervention at the school, family, and community levels have been conducted in the Tehran Lipid and Glucose Study framework. A total of 2145 children (4–18 years, 49% boys, and 18% intervention) were recruited for the baseline assessment and were followed through five follow-up examinations during a median of 16.1 years. Using a group-based trajectory model, BMI trajectories from childhood to young adulthood were identified, and their association with the implemented intervention was assessed.

Results

Four trajectory groups of BMI from childhood to young adulthood were identified, including Normal weight (41%), Young adulthood overweight (36%), Early childhood increasing overweight and adulthood obesity (19%), and Early childhood increasing obesity (4%). Only Young adulthood overweight and Early childhood increasing obesity were affected by the intervention and were concomitant with lower BMI levels than the control group, with the highest estimated effect in the latter (β=-0.52 and p = 0.018; β=-1.48 and p < 0.001, respectively).

Conclusion

The current findings indicate the highest effectiveness of a practical, healthy lifestyle intervention on those whose obesity started in the early years of life or youth. Our results could help policymakers and planners design more targeted lifestyle modification and weight control interventions.

Trial registration

This study is registered at Iran Registry for Clinical Trials, a WHO primary registry (http://irct.ir). The Iran Registry for Clinical Trials ID and date are IRCTID:IRCT138705301058N1, 29/10/2008.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-14306-2.

Pregnancy loss and subsequent risk of prediabetes, diabetes and metabolic syndrome in couples: Tehran lipid and glucose study

Background

There is limited evidence regarding the impact of pregnancy loss on the subsequent risk of metabolic disorders. We aimed to investigate whether history of pregnancy loss is associated with the subsequent risk of prediabetes (pre-DM), diabetes (DM), and metabolic syndrome (METs) among couples.

Method

In this population-based cohort study, 2765 couples with and without history of pregnancy loss and free of DM, pre-DM, and METs at baseline were included and followed for incidents of DM, pre-DM, and METs by 3-year intervals visits from 1999 to 2018. Detailed data of variables was collected using standard questionnaires, interviews, clinical and laboratory assessments. A modified Poisson regression for binary outcome data with a log link function and robust error variance was used to estimate relative risks (RRs) in couples with and without history of pregnancy loss. Both unadjusted and adjusted models were fitted, and effect measures were calculated.

Result

During a median follow-up of 15 years, females with history of pregnancy loss were experienced more pre-DM (50% vs. 45.5%), DM (28.9% vs. 21.3%), and METs (70% vs. 60.1%) than females without such history. Moreover, history of pregnancy loss increased the risk of METs by 8% among females. The incidence of DM in males with history of pregnancy loss in their spouses was higher than in males without it (28.8% vs. 23.5%). Among males, having a spouse with history of pregnancy loss was positively associated with the risk of pre-DM (RR = 1.12; 95%CI: 1.02, 1.23, p = 0.02); furthermore, they were more prone to the risk of METs than females with a history of pregnancy loss (RR = 1.13; 95%CI: 1.07, 1.20, p < 0.001).

Conclusion

Although pregnancy loss is a female-specific factor, may foreshadow the subsequent METs, our study identified a higher risk of subsequent pre-DM and METs in males with history of pregnancy loss in their spouses. Pregnancy loss could be considered a possible future risk factor for metabolic disorders in couples.

Dietary oxalate to calcium ratio and incident cardiovascular events: a 10-year follow-up among an Asian population

Background and aim

The potential cardiovascular impact of usual intakes of oxalate (Ox) is uninvestigated. We evaluated the effect of dietary Ox and its interaction with dietary calcium (Ca) on incident cardiovascular disease (CVD).

Methods

We included 2966 adult men and women aged 19–84 y without known CVD during baseline enrollment (2006–2008) of the Tehran Lipid and Glucose Study. Dietary intakes were assessed using a validated FFQ, and incident CVD (i.e., coronary heart disease, stroke, and CVD mortality) were documented through March 2018.

Results

A 7.1% incident of CVD occurred during a median follow-up of 10.6 y. After multivariable adjustment for traditional risk factors and key dietary nutrients, including total fat and fiber, Ox intakes ≥220 mg/d increased incident CVD (HR T3 vs. T1 = 1.47, 95% CI = 1.02–2.12). This association was potentiated (HR T3 vs. T1 = 2.42, 95% CI = 1.19–4.89) in subjects who had a lower intake of Ca (< 981 mg/d); in a low-Ca diet, an even lower amount of dietary Ox (second tertile, 148–220 mg/d) was related to increased CVD events by 92% (HR = 1.92, 95% CI = 1.00–3.70). No association was observed between dietary Ox and CVD events in the presence of medium- and high levels of Ca intakes. The critical cut-off point of Ox-to-Ca for predicting CVD events was 0.14, which was related to an increased risk of CVD by 37% (HR = 1.37, 95% CI = 1.02–1.84).

Conclusion

Higher dietary Ox intake appeared to be associated with a modestly elevated risk of incident CVD, especially in a diet with a lower amount of Ca.

Monitoring population salt intake using casual urinary sodium: Tehran Lipid and Glucose Study

Background

We aimed to estimate salt intake among an Iranian population using spot urine-based equations and a dietary-based method.

Methods

Adult men and women (n = 2069) were recruited from the Tehran Lipid and Glucose Study (2014–2017). Urinary sodium (Na), potassium (K), and creatinine (Cr) concentrations were measured in the morning spot urine samples. The 24-h urinary Na excretion and predicted salt intake was estimated using five equations, i.e., Kawasaki, Tanaka, Intersalt, Toft, and Whitton. A validated food frequency questionnaire (FFQ) was used to obtain dietary intake of salt. The agreement of each urinary- and FFQ-based salt estimation with the overall mean of the methods, considered as the gold standard, was assessed using the Bland–Altman method.

Results

Mean age of the participants was 45.6 ± 14.8 y, and 45.4% were men. Mean (SD) estimated salt intake, derived from the overall mean of the methods, was 9.0 ± 2.2 g/d (10.2 ± 2.1 and 7.9 ± 1.7 g/d in men and women, respectively). Mean bias of the estimations from the overall mean ranged from − 0.2.42 to 2.75 g/d, with the Tanaka equation having the least bias (mean bias = 0.13 ± 1.10, 95% CI − 2.37, 2.30 g/d). Tanaka estimated a mean salt intake of 8.9 g/d (range 2.1 to 18.7 g/d); accordingly, only 5.1% of participants adhered to the recommendation (< 5 g/d salt intake), whereas 26.8% and 2.4% exceeded the recommendation by 2- and threefold.

Conclusion

The Tanaka equation could provide a more accurate mean-population estimated salt intake from casual urinary Na concentration in our population. About 95% of the Iranian population exceeded the current recommendations of salt intake.

Sex Differences in Cumulative Exposure to Metabolic Risk Factors Before Hypertension Onset: The Cohort of the Tehran Lipid and Glucose Study

Background

Previous studies have shown a sex difference in the association between hypertension and cardiovascular disease; however, the precise mechanism remains unclear. Because there are strong associations between metabolic risk factors (MRFs) and hypertension, a sex‐specific analysis of MRFs before hypertension onset could offer new insights and expand our understanding of sex differences in cardiovascular disease. We evaluated cumulative exposure to major MRFs and rate of change of those factors, including body mass index, waist circumference, systolic blood pressure, diastolic blood pressure, fasting plasma glucose, total cholesterol, triglycerides, and high‐density lipoprotein cholesterol among individuals who did and did not develop hypertension at follow‐up.

Methods and Results

We included 5374 participants (2191 men) initially without hypertension with age range of 20–50 years at baseline who participated in the Tehran Lipid and Glucose Study, and had been examined at least 3 times during the study period (1999–2018). In both sexes, the cumulative exposure to all MRFs (except for fasting plasma glucose and high‐density lipoprotein cholesterol in men) were higher in those who developed hypertension, compared with those who did not develop hypertension. However, women experienced greater cumulative exposure to major MRFs, compared with their male counterparts. Also, they experienced a faster increase in waist circumference, systolic blood pressure, diastolic blood pressure, and high‐density lipoprotein cholesterol than men. Furthermore, rapid increase in systolic blood pressure began earlier in women than men, at the age of 30 years. We also found that those men who developed hypertension experienced unfavorable change in major MRFs during young adulthood (<50 years of age).

Conclusions

Women exhibited more metabolic disturbances than men before onset of hypertension, which may explain the stronger impact of hypertension for major types of cardiovascular disease in women, compared with men.

Developmental trajectories of body mass index since childhood and health-related quality of life in young adulthood: Tehran Lipid and Glucose Study

PURPOSE

The association between long-term BMI changes since childhood and health-related quality of life (HRQoL) in adulthood is still unclear. This study aimed to examine the association between identified BMI trajectories and HRQoL.

METHODS

A population-based cohort of 1938 eligible children (3-18 years) and their parents have been repeatedly followed up for 18 years. Offspring BMI trajectories were identified using group-based trajectory models. HRQoL was evaluated in offspring aged 21-36 years using SF-12V2. Using quantile regression analysis, the associations of the identified BMI trajectories and HRQoL in young adulthood were examined.

RESULTS

In males, persistent increasing overweight/obese group was negatively associated with 30th, 40th, 50th, and 60th percentiles of physical component summary (PCS) score distribution (β = - 2.60, p = 0.006; β = - 2.01, p = 0.005; β = - 1.86, p = 0.001; β = - 1.98, p = 0.009, respectively). A similar result was observed only in the 40th percentile of PCS distribution for the progressive overweight group (β = - 1.03, p = 0.022). In addition, the progressive overweight group in males showed a positive association with the upper tail of mental component summary (MCS) score distribution specifically for the 90th percentile (β = 1.15, p = 0.036). Regarding females, the current results indicated that the 90th percentile of MCS distributions was decreased in the persistent increasing overweight/obese group for females (β = - 1.83, p = 0.024). In addition, the progressive overweight group in females had a positive association with lower (30th and 40th) percentiles of PCS distribution (β = 1.29, p = 0.034, and β = 1.15, p = 0.030, respectively).

CONCLUSION

A sex-specific conditional association between developmental BMI trajectories from childhood and HRQoL in young adulthood was observed in physical and mental HRQoL.

Endogenous estrogen exposure and chronic kidney disease; a 15-year prospective cohort study

BACKGROUND

Despite strong evidence demonstrating the role of estrogen as a protective factor for kidney function in women, limited data are available regarding the influence of endogenous estrogen exposure (EEE) on chronic kidney disease (CKD). The present study aimed to assess the incidence of CKD in women with various levels of EEE.

METHODS

In a prospective population-based study over a 15-year follow-up, a total of 3043 eligible women aged 30-70 years, participating in Tehran-Lipid and Glucose-Study were recruited and divided into two groups (EEE < 11 and EEE ≥ 11 years). EEE calculated based on age at menarche, age at menopause, number and duration of pregnancies, lactation, and duration of oral contraceptive use after excluding the progesterone dominant phase of the menstrual cycle. Cox's proportional hazards model was applied to estimate the hazard ratio of CKD between the study groups, after adjusting for confounders.

RESULTS

The total cumulative incidence rate of CKD was 50.1 per 1000 person years; 95% CI: 47.7-52.6); this was 53.9 (95%CI, 50.2-57.8) and 47.1 (95%CI, 44.0-50.4) per 1000 person years in women with EEE < 11 and EEE ≥ 11 years, respectively. The model adjusted for age, BMI, smoking, hypertension, and diabetes showed that the hazard ratio (HR) of incidence CKD in women with EEE < 11 compare to those with EEE ≥ 11 years in the subgroup of women aged< 45 years was 2.66(95% CI, 2.2, 3.2), whereas, in the subgroup aged ≥45 years, it was 1.22 (95% CI, 1.04, 1.4).

CONCLUSION

This study shows a higher HR of CKD incidence in women with low EEE levels in their later life. Screening of these women for CKD may be recommended.

Sex- specific clustering of metabolic syndrome components and incidence of cardiovascular disease: A latent class analysis in a population-based cohort study

BACKGROUND

The prevalence of metabolic syndrome (MetS) is rapidly increasing in the world; also, the importance of management of MetS to decrease the risk of cardiovascular disease (CVD) has been recognized worldwide. This study aimed to explore the clusters of participants based on MetS components and its association with CVD outcomes.

METHODS

We included 2598 middle-aged participants (1545 women and 1053 men), 45-65 years old, at baseline and without prior CVD history. Participants were followed up for 10years. We conducted a latent class analysis based on MetS components. Subsequently, the relationship between latent classes and the incidence of CVD was investigated using Cox regression models adjusted for the main confounders.

RESULTS

During the study period, 393 (186 women and 207 men) new cases of CVD were identified among participants. In both genders, four distinct latent classes were identified: (1) Mets class (its prevalence rate in men: 19.6%, women: 27.7%), (2) Hypertension class (men: 12.1%, women: 13.7%), (3) Dyslipidemia class (men: 31.7%, women: 30.7%), (4) Low risk class (men: 39.3%, women: 30.5%). Compared with low-risk class, in both genders, Mets and hypertension classes were significant predictors of incident CVD. However, dyslipidemia class was a significant predictor just in women.

CONCLUSION

We found four subclasses in both genders indicating the same patterns of MetS latent classes in men and women. However, the relationship between subclasses of MetS and incident CVD varied by gender. These results suggest that the etiology of MetS involve more than one pathway and giving equal weight to each component or using the same cut-off values in both genders need to be reconsidered.

The dynamics of metabolic syndrome development from its isolated components among Iranian adults: findings from 17 years of the Tehran lipid and glucose study (TLGS)

Background

Evaluating the process of changes in the Metabolic Syndrome (MetS) components over time is one of the ways to study of the MetS natural history. This study aimed to determine the trend of changes in the progression of MetS from its isolated components.

Methods

This longitudinal study was performed on four follow-up periods of the Tehran Lipid and Glucose Study (TLGS) between 1999 and 2015. The research population consisted of 3905 adults over the age of 18 years. MetS was diagnosed based on the Joint Interim Statement (JIS). The considered components were abdominal obesity, hypertension, hyperglycemia, and dyslipidemia.

Results

The highest incidence of MetS from its components was related to hypertension in the short term (3.6-year intervals). In the long run, however, the highest increase in the MetS incidence occurred due to abdominal obesity. Overall, the incidence of MetS increased due to obesity and dyslipidemia, but decreased due to the other factors. Nonetheless, the trend of MetS incidence from all components increased in total. The most common components were dyslipidemia with a decreasing trend and obesity with an increasing trend during the study.

Conclusion

The results indicated that obesity and hypertension components played a more important role in the further development of MetS compared to other components in the Iranian adult population. This necessitates careful and serious attention in preventive and control planning.

Sex Differences in Rates of Change and Burden of Metabolic Risk Factors Among Adults Who Did and Did Not Go On to Develop Diabetes: Two Decades of Follow-up From the Tehran Lipid and Glucose Study

OBJECTIVE

We investigated the cumulative burden and linear rates of change of major metabolic risk factors (MRFs) among Iranian adults in whom type 2 diabetes did and did not develop.

RESEARCH DESIGN AND METHODS

We included 7,163 participants (3,069 men) aged 20-70 years at baseline with at least three examinations during 1999-2018. Individual growth curve modeling was used for data analysis. Statistical interactions for sex by diabetes status were adjusted for age, family history of diabetes, smoking status, and physical activity level.

RESULTS

Study sample included 743 (316 men) new case subjects with diabetes. In both men and women, compared with individuals in whom diabetes did not develop, individuals in whom diabetes developed had a higher burden of all MRFs and a greater rate of change in BMI, fasting plasma glucose (FPG), systolic blood pressure (SBP), and diastolic blood pressure; however, the differences in burden and rate of change between those who did and did not develop diabetes were greater in women than in men. During the transition to diabetes, women experienced more adverse change in BMI, FPG, triglyceride, and HDL cholesterol (HDL-C) (diabetes-sex interaction P values <0.05) and faster rates of change in BMI, FPG, HDL-C, and total cholesterol (interaction P values <0.01) and SBP (interaction P = 0.055) than men.

CONCLUSIONS

The greater exposure of women to and burden of MRFs before onset of diabetes may have implications for implementing sex-specific strategies in order to prevent or delay diabetes complications.

Dietary intakes of flavonoids and carotenoids and the risk of developing an unhealthy metabolic phenotype

This study was designed to investigate prospective associations between dietary habitual intakes of flavonoids and carotenoids and the development of an unhealthy metabolic phenotype. In this study 1114 adults, who had a healthy metabolic phenotype in the third examination cycle (2005-2008) participated. Dietary intakes of flavonoids and carotenoids were estimated using valid food frequency questionnaires evaluated during the study. Joint Scientific Statement criteria were used to define a metabolic unhealthy phenotype as meeting at least two criteria. During a median follow-up of 5.4 years, one standard deviation increase in total flavonoids reduced the risk of developing an unhealthy phenotype by 50% (95% CIs: 0.42-0.59), and inverse associations were observed for individual classes except anthocyanins, being the strongest for flavan-3-ols. Among carotenoid classes, a significant inverse association was only observed between lutein + zeaxanthin (HRs: 0.87, 95% CIs: 0.77-0.98) and the occurrence of an unhealthy phenotype. When data were stratified by baseline BMI, total flavonoids and individual classes of flavan-3-ols, flavonols, and flavones among both normal weight and overweight/obese individuals, isoflavones in those with excess weight and anthocyanins in normal weight individuals were inversely associated with the development of an unhealthy phenotype. Total carotenoids, β-carotene and lutein + zeaxanthin were significantly associated with the lower likelihood of the occurrence of an unhealthy phenotype, only among normal weight individuals. Higher intakes of flavonoids and their individual classes may contribute to the lower risk of a metabolic unhealthy phenotype in both normal weight and overweight/obese adults. Flavonoids may have more favorable metabolic health effects than carotenoids.

Do dietary intakes influence the rate of decline in anti-Mullerian hormone among eumenorrheic women? A population-based prospective investigation

BACKGROUND

Dietary intakes are suggested to affect age at menopause but associations between dietary factors and ovarian reserve reduction have not yet been investigated. We aimed to examine dietary intakes in relation to the rate of decline in anti-Mullerian hormone (AMH), an indicator of ovarian reserve, in a generally healthy cohort of women.

METHODS

This prospective investigation was conducted among 227 eumenorrheic women, aged 20-50 years, from the Tehran Lipid and Glucose study, who were followed over a mean of 16 years. AMH was measured twice, at baseline and the 5th follow-up examination cycle, and yearly rate of decline in AMH was calculated. Rapid decline in AMH was defined as the annual percent change AMH > 5.9%/year based on tertile 3 of the variable. Average usual dietary intakes were estimated using the food frequency questionnaires administered at the second, third, and the fourth follow-up examinations. After adjusting for potential covariates, the association between dietary factors and both risk of rapid decline in AMH and also annual percent decline of AMH (as a continuous variable) were examined using logistic regression and the Spearman correlation, respectively.

RESULTS

The baseline age of the participants and the median rate of decline in AMH were 37.2 years and was 5.7% yearly, respectively. The odds of rapid decline in AMH was reduced by 47% for dairy products (95% CIs = 0.36, 0.79; p = 0.002), 38% for milk (95% CIs = 0.41, 0.93; p = 0.020), and 36% for fermented dairy (95% CIs = 0.45, 0.93, p = 0.018) per one standard deviation (SD) increase in their dietary intakes. The odds of rapid decline in AMH was significantly reduced with higher intakes of fat, carbohydrate, protein, and calcium intakes from dairy sources, lactose and galactose. Annual rate of AMH decline was inversely correlated with dairy products, milk, fermented dairy, fruits, dairy carbohydrate, dairy fat, dairy protein, total calcium and dairy calcium, lactose and galactose, and positively correlated with organ meats.

CONCLUSION

Dairy foods consumption may reduce the rate of AMH decline in regularly menstruating women. Life style modification in terms of dietary advice may be considered as a preventive strategy for reduction in the rate of ovarian reserve loss.

Metabolic health in the Middle East and north Africa

The Middle East and north Africa are home to different populations with widely varying cultures, histories, and socioeconomic settings. Hence, their health status, health management, and access to appropriate health care differ accordingly. In this Review, we examine data on the historical and prospective status of metabolic diseases in this region including obesity, diabetes, hypertension, dyslipidaemia, and non-alcoholic fatty liver disease. Women in the Middle East and north Africa have the highest risk of metabolic diseases of all women globally, whereas men rank second of all men in this respect. Metabolic risk factors are responsible for more than 300 deaths per 100 000 individuals in this region, compared with a global mean of fewer than 250. Physical inactivity, especially in women, and an unhealthy diet (ie, low consumption of whole grains, nuts, and seafoods) stand out. More than one in every three women are obese in most countries of the region. Prevention programmes have not fully been achieved in most of these countries and the projected future is not optimistic. Comprehensive surveillance and monitoring of metabolic diseases, robust multisectoral systems that support primordial and primary preventions, continuous education of health-care providers, as well as collaboration between countries for joint projects in this region are urgently needed to overcome the paucity of data and to improve the metabolic health status of inhabitants in the Middle East and north Africa.