Associations of drinking rainwater with macro-mineral intake and cardiometabolic health: a pooled cohort analysis in Bangladesh, 2016\u20132019

Abu Mohd Naser,Matthew O Gribble,K M Venkat Narayan,Leanne Unicomb,Golam Kibria Khan,Shariful Islam,Sarker Masud Parvez,Mohammad Shamsudduha,Thomas F Clasen,Shuchi Anand,Stephen P Luby,Mahbubur Rahman,Kazi Matin Ahmed,Solaiman Doza

doi:10.1038/s41545-020-0067-5

Abstract

This study explores the associations of drinking rainwater with mineral intake and cardiometabolic health in the Bangladeshi population. We pooled 10030 person-visit data on drinking water sources, blood pressure (BP) and 24-h urine minerals. Fasting blood glucose (FBG) was measured in 3724 person-visits, and lipids in 1118 person-visits. We measured concentrations of sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) in 253 rainwater, 935 groundwater and 130 pond water samples. We used multilevel linear or gamma regression models with participant-, household- and community-level random intercepts to estimate the associations of rainwater consumption with urine minerals and cardiometabolic biomarkers. Rainwater samples had the lowest concentrations of Na, K, Ca and Mg. Rainwater drinkers had lower urine minerals than coastal groundwater drinkers: −13.42 (95% CI: −18.27, −8.57) mmol Na/24 h, −2.00 (95% CI: −3.16, −0.85) mmol K/24 h and −0.57 (95% CI: −1.02, −0.16) mmol Mg/24 h. The ratio of median 24-hour urinary Ca for rainwater versus coastal groundwater drinkers was 0.72 (95% CI: 0.64, 0.80). Rainwater drinkers had 2.15 (95% CI: 1.02, 3.27) mm Hg higher systolic BP, 1.82 (95% CI: 1.19, 2.54) mm Hg higher diastolic BP, 0.59 (95% CI: 0.17, 1.01) mmol/L higher FBG and −2.02 (95% CI: −5.85, 0.81) mg/dl change in high-density lipoprotein cholesterol compared with the coastal groundwater drinkers. Drinking rainwater was associated with worse cardiometabolic health measures, which may be due to the lower intake of salubrious Ca, Mg and K.

Highlights

Rainwater harvesting is currently practiced worldwide for potable and non-potable uses[1]
Compared with person-visits of pond water drinkers, those among rainwater drinkers had 0.91 [95% confidence interval (CI): −0.54, 2.36] mm Hg change in SBP, 0.53 [95% CI: −0.39, 1.44] mm Hg change in DBP, −0.04 mmol/L increase in Fasting blood glucose (FBG), −3.40 mg/dl change in HDL-C and −1.18 mg/dl change in total cholesterol in fully adjusted models (Table 5)
We found that drinking rainwater was associated with a higher SBP (P-value:

Summary

INTRODUCTION

Rainwater harvesting is currently practiced worldwide for potable and non-potable uses[1]. To address water salinity problems, rainwater-harvesting systems and pond sand filters near rainwater-fed ponds are currently being promoted in southwest coastal Bangladesh[15,16] These systems capture rainwater during the wet season when sufficient rainfall is available and conserve water for future use during the dry season. Calcium (Ca), magnesium (Mg) and potassium (K) are essential macrominerals for humans, inadequate intake of which is associated with cardiovascular events[19,20,21], and these minerals are present at low or negligible levels in rainwater This raises concern that rainwater may have detrimental effects on cardiometabolic health of the population, compared with alternative sources of water. We conducted an observational epidemiology study comparing rainwater drinkers versus other water (e.g., groundwater and surface water) drinkers for biomarkers of essential macrominerals, and for cardiometabolic parameters (urine protein, blood pressure, blood glucose and blood lipids) in Bangladesh

RESULTS

DISCUSSION

Findings

METHODS