Exploring dietary influences on cardiovascular and renal health

11 May 2016 – A sodium-reduced diet and a diet high in potassium: both of them reduce blood pressure. But what happens when the two are combined in one diet? This was TiFN PhD fellow Ineke Riphagen’s research question. She identified that consuming extra potassium when someone is following a low sodium diet has only minor additional blood pressure-lowering effects.

Riphagen’s research has greatly increased our understanding of the mechanisms involved in blood-pressure lowering effects of potassium during sodium restriction.

Riphagen explored the effects of diet on blood pressure and fluid balance in a group of 35 subjects with high blood pressure. She combined several existing biomarkers, including copeptin, natriuretic peptides, renin and aldosterone. “We wanted a complete picture of the mechanisms at work”, she explains.

Counter-regulatory mechanisms
Potassium supplementation was found to have a relatively small blood pressure-lowering effect during sodium restriction. “The effects seemed mitigated by activation of several counter-regulatory mechanisms involved in regulation of fluid balance and blood pressure, such as vasopressin, the renin-angiotensin-aldosterone system (RAAS) and heart rate”, says Riphagen.

In addition to high blood pressure, vascular calcification is an important risk factor for cardiovascular disease. The calcification process is counteracted by the vitamin K-dependent Matrix Gla protein (MGP), a protein that stays inactive in case of vitamin K deficiency. Riphagen used MGP to measure how often people in the general population suffer from vitamin K deficiency. “The condition appeared to be surprisingly common, especially among elderly and patients with chronic diseases”, she says. Furthermore, vitamin K deficiency was associated with an increased mortality risk.

Constructive collaboration

The PhD fellow appreciated her time at TiFN. “The research was interesting and challenging, and I enjoyed the constructive collaboration with my colleagues,” she says. “Coming from different fields of expertise, everyone looked at issues from another perspective, which was very instructive.”