Dietary intakes of total, nonheme, and heme iron and hypertension risk: a longitudinal study from the China Health and Nutrition Survey

A cross-sectional analysis of the PURE study on minerals intake among Malaysian adult population with hypertension

Hypertension (HPT) is the leading modifiable risk factor for cardiovascular diseases and premature death worldwide. Currently, attention is given to various dietary approaches with a special focus on the role of micronutrient intake in the regulation of blood pressure. This study aims to measure the dietary intake of selected minerals among Malaysian adults and its association with HPT. This cross-sectional study involved 10,031 participants from the Prospective Urban and Rural Epidemiological study conducted in Malaysia. Participants were grouped into HPT if they reported having been diagnosed with high blood pressure [average systolic blood pressure (SBP)/average diastolic blood pressure (DBP) ≥ 140/90 mm Hg]. A validated food frequency questionnaire (FFQ) was used to measure participants' habitual dietary intake. The dietary mineral intake of calcium, copper, iron, magnesium, manganese, phosphorus, potassium, sodium, and zinc was measured. The chi-square test was used to assess differences in socio-demographic factors between HPT and non-HPT groups, while the Mann-Whitney U test was used to assess differences in dietary mineral intake between the groups. The participants' average dietary intake of calcium, copper, iron, magnesium, manganese, phosphorus, potassium, selenium, sodium, and zinc was 591.0 mg/day, 3.8 mg/day, 27.1 mg/day, 32.4 mg/day, 0.4 mg/day, 1431.1 mg/day, 2.3 g/day, 27.1 µg/day, 4526.7 mg/day and 1.5 mg/day, respectively. The intake was significantly lower among those with HPT than those without HPT except for calcium and manganese. Continuous education and intervention should be focused on decreasing sodium intake and increasing potassium, magnesium, manganese, zinc, and calcium intake for the general Malaysian population, particularly for the HPT patients.

Chinese Healthy Eating Index (CHEI) and risk of diabetes in Chinese adults: a prospective cohort study

PURPOSE

The Chinese Healthy Eating Index (CHEI) is a valid instrument to assess the diet quality of the Chinese population, but evidence regarding the relationship between CHEI and the risk of diabetes remains limited. We aimed to investigate the prospective association of CHEI with diabetes among Chinese adults.

METHODS

1563 adults free of diabetes at baseline and with at least two survey data from 1997 to 2018 were included. Dietary information was collected by three consecutive 24-h recalls combined with household food inventory, and long-term diet quality was evaluated by the CHEI. Diabetes was defined as self-reported physician-diagnosed diabetes and/or fasting blood glucose ≥ 7.0 mmol/L, and/or HbA1c ≥ 6.5%. Cox proportional hazard models and restricted cubic spline analysis were used to estimate the associations between CHEI and diabetes.

RESULTS

During a median follow-up of 12.0 years, 192 (10.3%) participants developed new-onset diabetes. Generally, a five-point higher CHEI score was significantly associated with a 17% lower risk of diabetes (HR, 0.83; 95%CI 0.71-0.97). In stratified analysis, inverse associations between CHEI and diabetes were more vigorous in females (HR, 0.68; 95%CI 0.54-0.85) than in males (P for interaction = 0.01). In addition, there was an L-shaped association between CHEI and diabetes risk in the whole population (P for non-linearity = 0.026), while no significant non-linear association was observed in females or males, respectively.

CONCLUSION

Our results suggested that a long-term higher-quality diet evaluated by CHEI was significantly associated with lower risks of diabetes, and the favorable associations were more pronounced among females.

The Association of Iron Intake and Hypertension, Does Iron Intake Decrease Blood Pressure?

Previous studies reported that iron may have an indispensable role in the risk of hypertension (HTN). However, the result of the studies on the relationship between iron and risk of HTN is inconsistent. This study aimed to assess the association between the association of dietary iron intake and HTN in the Iranian population. This case-control study was conducted on 4184 people aged 35 to 70, including 1239 people with HTN and 2945 people with normal blood pressure (BP) in Sabzevar, Iran. Dietary intake was assessed using a food frequency questionnaire (FFQ). The Nutritionist IV software was used in terms of the assessment of dietary intake of iron. An inverse association was found between iron intake and HTN (OR = 0.97, CI 95%: 0.94-0.99, P = 0.04). The association remained significant after adjustment for age, gender, smoking, drinking alcohol, calorie intake, and BMI (OR = 0.94, CI 95%: 0.89-0.98, P = 0.01). As a conclusion, iron intake was inversely associated with HTN. Further longitudinal studies on the effect of iron intake on BP are required to confirm this finding.

Reliability and validity of a semi-quantitative food frequency questionnaire: dietary intake assessment among multi-ethnic populations in Northwest China

BACKGROUND

Few multi-ethnic dietary culture-sensitive food frequency questionnaires (FFQ) have been developed due to the complexity and diversity of cooking methods and styles. This study aimed to develop and validate a specific FFQ among multi-ethnic groups in Northwest China.

METHODS

In the reliability study, 139 participants aged 20-65 completed two identical FFQs separated by 3 months. The relative validation of the FFQ was assessed by three 24-h recalls (24HR) employed in the interval of two FFQs, as a reference. Stratified analyses were also conducted by the major ethnic groups (Han nationality or Ethnic minority).

RESULTS

For reproducibility, the median (range) of Spearman's correlation coefficients (SCC) was 0.71 (0.43-0.84) for nutrients. The intra-class correlation coefficients (ICC) covered a spectrum from 0.39 to 0.78 (median: 0.64). Meanwhile, the weighted kappa values ranged from 0.11 to 0.64. For validity, the median (range) of Pearson's correlation coefficients derived from the energy unadjusted and the adjusted values between FFQ and 24HR were 0.61 (0.12-0.79) and 0.56 (0.12-0.77), respectively. The results of correlation coefficients were similar between the two ethnic groups. Moreover, the Bland-Altman plots likewise demonstrated a satisfactory level of agreement between the two methods.

CONCLUSIONS

The FFQ showed acceptable reproducibility and moderate relative validity for evaluating dietary intake among multi-ethnic groups in northwest China. It could be a credible nutritional screening tool for forthcoming epidemiological surveys of these populations.