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[ISLAMABAD] Manganese and selenium as micronutrients can counter the hypertensive effect of lead in blood, say the results of a new study conducted in Bangladesh.
Globally, hypertension affects a billion people and accounts for 7.5 million deaths annually, according to the WHO. Considered a lifestyle disease, environmental factors such as air pollution due to the use of leaded fuels, are also known to be responsible for the rise in blood pressure.
“The two vital micronutrients are highly protective and they decrease blood pressure… We also found they offset the harmful effects of sodium, mostly taken as table salt, on blood pressure”
Maria Argos, University of Illinois
Published this month (May) in Environmental Pollution, the joint study by researchers from Bangladesh and the US considered changes in blood pressure associated with lead, and looked at manganese and selenium as beneficial dietary micronutrients for those who are regularly exposed to high levels of lead contamination.
"The two vital micronutrients are highly protective and they decrease blood pressure," Maria Argos, study author and assistant professor at the School of Public Health, University of Illinois, Chicago, tells SciDev.Net. "We also found they offset the harmful effects of sodium, mostly taken as table salt, on blood pressure."
Heavy metal contamination is endemic in Bangladesh where elevated exposure to certain toxic metals can result in hypertension. Lead is highly endemic in Bangladesh because of a number of factors, according to a study by the National Center for Biotechnology Information. These include lack of a proper waste management system and monitoring of lead content in pesticides, and, due to physical labour, regular exposure to more than 200 hazardous conditions which likely bring about lead exposure. An estimated 20 per cent of the adult population of Bangaldesh suffers from hypertension, with the rate increasing to more than half in the elderly population, according to a survey published in 2012.
The researchers, who were studying arsenic-related skin cancer, weighed up levels of lead, manganese and selenium in the blood and measured blood pressure at baseline and at three biennial follow-up examinations.
According to Argos, the study findings indicated a direct, linear association of lead exposure with systolic blood pressure that measures the force of blood pumped through the body when heart contracts. But the combination of mid-range manganese and high selenium concentrations completely offset lead-associated blood and pulse pressure.
Afzalur Rahman, director of the National Institute of Cardiovascular Diseases, Dhaka, says the study results show the potential of using manganese and selenium as anti-hypertensive agents to treat Bangaldesh’s lead-exposed population.
"The findings are vital for the country’s health sector policymakers and practitioners to contain hypertension that has become a major public health and socio-economic concern in Bangladesh," Rahman tells SciDev.Net.
Manganese is found in nuts, legumes, seeds, tea, whole grains and leafy green vegetables while selenium can be found in fish like tuna, cod, red snapper and herring and also in beef, poultry, grains and nuts.Former WHO country coordinator for non-communicable disease control, Muhammad Mostafa Zaman, says the study findings are particularly welcome in Bangladesh where medicines against hypertension are unaffordable for most people.
But another expert cautioned on making quick conclusions and suggested the need for more investigations on the role of the two identified micronutrients.
"The results are interesting but not enough to draw conclusions about the merits of manganese and selenium supplements in lead-exposed people," says a WHO scientist who declined to be named.
This piece was produced by SciDev.Net’s Asia & Pacific desk.