A new analysis published in the journal BMJ Open reveals that people from low socioeconomic groups in the UK eat more salt than their counterparts from higher socioeconomic groups, despite a national drop in salt intake over the last 10 years.
According to the study authors – led by Prof. Francesco Cappucio, director of the World Health Organization (WHO) Collaborating Centre for Nutrition at Warwick Medical School in the UK – high blood pressure is the most common and preventable cause of morbidity, disability and death worldwide. And it is responsible for over half of the deaths from coronary heart disease, stroke and cardiovascular disease (CVD).
They explain that CVD risk is fast becoming more prevalent in low- and middle-income countries, and that within countries, it is more prevalent in groups that are socially disadvantaged.
However, growing evidence has suggested that moderately reducing salt intake reduces blood pressure, in turn potentially reducing cardiovascular events and strokes.
As such, in 2003, the UK Food Standards Agency (FSA) implemented a salt reduction program that sought to reduce average salt intake to 6 g per day in the UK population.
In westernized countries – like the UK – around 75% of salt consumed comes from processed and restaurant foods, while 15% comes from consumers adding it at the table or while cooking.
Prof. Cappucio notes:
“The diet of disadvantaged socio-economic groups tends to be made up of low-quality, salt-dense, high-fat, high-calorie unhealthy cheap foods. We have seen a reduction in salt intake in Britain thanks to a policy […] However, clearly poorer households still have less healthy shopping baskets and the broad reformulation of foods high in salt has not reached them as much as we would have hoped.”
Social inequalities ‘explain more than 5% of salt consumption differences’
In their study, which is the first to monitor social inequalities in the wake of the national salt reduction program, the researchers assessed the geographical distribution of dietary salt intake in British people and its link with occupation and education – indicators of socioeconomic position and determinants of health.
In total, the team analyzed 1,027 men and women between the ages of 19 and 64 through the British National Diet and Nutrition Survey from 2008-2011.
The participants’ salt intake from food was determined through 4-day diaries, but salt added by consumers at the table and in cooking was not measured.
Results show that dietary sodium intake varied across socioeconomic groups, even when the researchers adjusted for geographical variations; in people with the lowest educational attainment and lower levels of occupation, the dietary sodium intake was higher.
The researchers say that despite the national salt reduction program, social inequalities in salt intake have not reduced, explaining more than 5% of salt consumption between more and less affluent groups.
“Whilst we are pleased to record an average national reduction in salt consumption coming from food of nearly a gram per day,” says Prof. Cappucio, “we are disappointed to find out that the benefits of such a program have not reached those most in need.”
He adds that their results are important since “people of low socioeconomic background are more likely to develop high blood pressure (hypertension) and to suffer disproportionately from strokes, heart attacks and renal failure.”
‘It is crucial to understand reasons for these social inequalities’
Though their study is the first to assess the impact of the national salt reduction program in the UK on social inequalities, the authors say there are a few limitations.
Firstly, they only assessed salt coming from food and did not include salt intake that participants may have added to their food at the table and during cooking.
Additionally, their results are based on white respondents of their survey, because “the representation of ethnic minority groups is still insufficient for independent analysis.” They also used a “relatively small number of spatial units and regional classifications.”
Still, they say understanding the socioeconomic pattern of salt intake is vital to reduce inequalities, and Prof. Cappuccio adds:
“In our continued effort to reduce population salt intake towards a 6 g per day target in Britain, it is crucial to understand the reasons for these social inequalities so as to correct this gap for an equitable and cost-effective delivery of cardiovascular prevention.”