Research Digest

Lab notes: High salt intake raises blood pressure, no matter how healthy one’s diet is

A study shows that eating more fruits and vegetables lowers but does not fully counteract the effects of dietary sodium.

A diet rich in fruit and vegetables may be good for a person’s health overall but does little to overcome the effects of salt in causing hypertension. A new study shows the importance of monitoring salt intake to maintain blood pressure.

Researchers from a number of institutions including Imperial College London and Northwestern University analysed the diets of more than 4,000 people and found that people eating higher amounts of salt had higher blood pressure, irrespective of the other aspects of their diets.

About 30% of the Indian population – that is one in three people in India – have hypertension with the disease becoming one of the most common lifestyle ailments in both urban and rural areas. High blood pressure is common in older adults but is increasingly being diagnosed in children as it is also brought on by excess weight and salt intake.

The researchers conducting the latest study analysed data from the years 1997 to 1999 that tracked the diets of 4,680 people, aged 40-59, from the United States, United Kingdom, Japan and China. Volunteers were tracked over four days, and two urine samples were taken during this time. Measurements of height, weight and blood pressure were also taken along with their dietary data for over 80 nutrients that may be linked to low blood pressure, including vitamin C, fibre, and omega-3 fatty acids.

The team assessed concentrations of sodium and potassium in the urine samples. Sodium is the main component of salt, while potassium, which is found in green leafy vegetables, has been linked to lower blood pressure. The researchers found a correlation between high blood pressure and higher salt intake, even in people who were eating a high amount of potassium and other nutrients.

Till now nutritionists and researchers have hypothesised that eating fruits and vegetables can counteract the effects of salt in diets. The results of the new study published in the journal Hypertension shows that while these foods do tend to lower blood pressure, they do not reverse the adverse effects of salt.

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