Mineral salts in diet could cut blood pressure, finds Finnish study

Finnish researchers, writing in the Nutrition Journal, found that replacement of regular salt (NaCl) with a novel mineral salt resulted in a significant reduction in systolic blood pressure (SBP) over 8 weeks while the SBP increased slightly in the regular salt group.

And the scientists argue that salt substitution in processed foods and table salt may have a large impact on cardiovascular health at population level.

“Recently published analysis demonstrated that reducing salt by 3 g per day is projected to reduce the annual number of new cases of CHD by 60,000 to 120,000 in the US alone,”​ reports the scientists.

The Finnish team also note that the observed decline in the prevalence of hypertension has levelled off and, therefore, there “is an evident need for public health measures aiming at more effective lifestyle modifications connected to high blood pressure, including the sodium intake levels.” ​

Objective ​

The goal of this study was to test the feasibility and effect of a new mineral salt (Smart Salt), which is low in sodium and high in potassium and magnesium, on blood pressure.

The Finnish team said their hypothesis was that the replacement of this mineral salt for regular salt covering at least 50 per cent of dietary sodium sources in a diet would lead to a 3 to 5 g reduction in sodium intake and consequently a lower blood pressure in subjects.

The supplementation of potassium and magnesium to a low-sodium diet may enhance the antihypertensive effect of a low-sodium diet, and thus be useful in treating hypertension, said the Finnish scientists.

They note that potassium has a natriuretic effect, promoting the excretion of sodium salts in the urine. Intake of magnesium may also support a reduction in blood pressure by reducing vascular resistance.

The study ​

A randomized, double-blind, placebo-controlled study was conducted with an intervention period of 8-weeks in subjects with systolic and/or diastolic blood pressure.

The authors said that subjects were recruited via announcements in the local newspapers and other sources. The participants were deemed eligible if they were between 25-75 years old, with their SBP in the range of 130-159 mmHg and/or DBP in the range of 85-99 mmHg, BMI between 23 and 40 kg/m2 and a stable body weight.

The test product was Smart Salt SMS50, which contains 50% sodium chloride (NaCl), 25% potassium chloride (KCl) and 25% magnesal; magnesium ammonium potassium chloride, hydrate. The control was a regular salt (sodium chloride, NaCl).

During the treatment period, the main food sources of salt were either salted as normal or with Smart Salt, depending on the study group, notes the article.

Test foods ​

Test foods, report the team, were industrially processed main dishes (casseroles, soups, pastas, pizza and minced meat dishes), bread (70 % rye bread and 30% multigrain), frankfurters sausage/cold cuts and Edam cheese.

Salt used for cooking and baking as well as table salt was either regular salt or Smart Salt, dependent on group.

The daily amount of the test foods in the study diet was based on national dietary data in Finland, namely the FinDiet 2007 study.

In the test group, the NaCl reduction was designed to be 3.1 to 5.6 grams (1.2 to 2.2 grams Na+) depending on the energy intake and habitual diet of the study subject.

The daily sodium intake in the regular salt group was designed to stay at the same level as typical for that individual. The amounts of Smart Salt and regular salt in recipes of test foods were the same. The analysed concentration of sodium (expressed as NaCl) in the test foods varied between 0.38-1.41% in Smart Salt foods and 0.64-2.03% in regular salt foods depending on the food matrix.

The primary endpoint was the change in SBP. Secondary endpoints were changes in DBP, daily urine excretion of sodium (24-h dU-Na), potassium (dU-K) and magnesium (dU-Mg), they added.

The authors note that 24-h dU-Na decreased significantly in the Smart Salt group and remained unchanged in the control group. Furthermore, they concluded that replacement of NaCl with Smart Salt resulted in a significant reduction in SBP over 8 weeks, while SBP increased (+3.8 mmH) slightly in the regular salt group.

Source: Nutrition Journal ​
Published online ahead of print: doi:10.1186/1475-2891-10-88
Title: Feasibility and antihypertensive effect of replacing regular salt with mineral salt rich in magnesium and potassium- in subjects with mildly elevated blood pressure​
Authors: Niskanen et al