Could an app lower your blood pressure?

A smartphone app called SaltSwitch, being trialled at the University of Auckland, does just that: scan a barcode and it will guide you to healthier, low-salt alternatives. The researchers hope to show that the app, combined with a low sodium, high potassium salt, will lower blood pressure in adults with high blood pressure – a pressing need in a country where one in five adults has high blood pressure, which leads to heart disease. The burden is also unequal: Māori are 30 percent more likely than non-Māori to have heart high blood pressure.

Heart Awareness Month is a good time to reflect on our salt-heavy ways: New Zealand adults on average consume about 40 percent more salt than the less-than-one teaspoon a day recommended by the World Health Organisation.

“It’s the sodium in salt that raises blood pressure, so by reducing sodium intake we can reduce the risk of heart disease,” says Dr Helen Eyles, a Senior Research Fellow at the National Institute of Health Innovation, based at the University, and lead investigator on the SALTS study. “These days, we hear a lot about the need to cut back on the sugar we eat, but salt is very important too.”

There is good evidence that mobile apps can help people make positive changes to their diets, and results from a small pilot study testing the SaltSwitch app with people with heart disease were promising.

Now, the app is being trialled in the Salt Alternatives Study (SALTS), run by a team from the University’s Faculty of Medical and Health Sciences. Researchers are seeking adults with high blood pressure who own a smart phone and live in the Auckland region.

Dr Eyles: “So far, people seem really excited to be involved in a study where they might be able to lower their blood pressure through dietary changes. Regardless of whether you’re on blood pressure pills or not, you can join the study. If you are already on medication, reducing salt can lower your blood pressure further.”

Each participant will be randomly allocated (like a coin toss) to receive either the SaltSwitch app along with the low sodium, high potassium salt, or general information about heart-healthy eating. All participants get a WiFi or SIM-enabled blood pressure monitor to provide home-based measures, and if they complete will be able to keep the monitor at the end of the study.

Results are expected in 2021. If you want to find out more, check out the study page or contact salts@auckland.ac.nz.

SALTS is funded by a Health Research Council programme grant, ‘Dietary Interventions: evidence & Translation (DIET)’; and has ethics approval from the Health and Disability Ethics Committees. Dr Eyles is supported by a Heart Foundation of New Zealand Senior Fellowship.