New Danish research reveals that a change of diet, with fewer additives and plenty of vegetables, fruit and fibre, reduces the risk of developing cardiovascular diseases. This applies in particular to patients with chronic reduced kidney function but can also be relevant for others.
"Many Danes eat far too much meat and convenience food with additives, and this stresses the kidneys. And that's not good if you're a kidney patient," said Louise Salomo, MD, who completed her PhD project about Ny Nordisk Nyrevenlig Hverdagsmad (New Nordic Kidney-Friendly Everyday Food) at the Department of Nephrology in 2018.
Phosphate is dangerous
When the body's kidney function is impaired, increasing amounts of phosphate will accumulate in the blood. Phosphate is a major cause of the high prevalence of cardiovascular diseases among patients with chronic kidney disease.
"Phosphate can be harmful to health, particularly if the kidneys do not function properly. If you eat a lot of meat, cold cuts and convenience food, your diet will often contain high concentrations of phosphate which can accumulate in the blood and result in hardening of the arteries. Therefore, what you put in your mouth everyday matters," said Louise Salomo.
The development of high levels of phosphate in the blood can be controlled in two ways. One way is through medicine, and the other is by reducing intake of phosphate via your diet.
"Cutting down on medicine is a huge advantage for kidney patients. They already have a very high medicine burden. Moreover, the medicine contains phosphate binders, and these themselves can cause hardening of the arteries," said Louise Salomo.
New Nordic kidney-friendly food
The research group developed a special low-phosphorous diet for the trial. The diet prevents interruptions in the phosphate balance in patients with moderate chronic kidney disease. The diet was developed on the basis of Ny Nordisk Hverdagsmad (New Nordic Everyday Food), which primarily consists of local, organic produce and less convenience food as well as plenty of fruit, vegetables, fibre and fish. But this was not enough.
"We removed the most phosphorous foods and modified the diet to "New Kidney-Friendly Nordic Everyday Food" with a total phosphate content of 850 mg/day. And this made all the difference," said Louise Salomo, and continued:
"The short-term effect of the new diet was demonstrated in patients with moderate chronic kidney disease - stage 3-4. The patients ate as usual for seven days and then they went on the "New Kidney-Friendly Nordic Everyday Food" diet for another seven days. The effect was measured on the difference in the release of phosphate in the urine on day seven.
Kidney-friendly recipes on the way
"In 2019, we're planning to publish a cookbook with guidelines and recipes that follow the principles from our study on "New Kidney-Friendly Nordic Everyday Food". The cookbook will be developed in collaboration with a chef. This will help spread our dietary recommendations to the Danish population. Our trial could indicate that perhaps we should start considering kidney disease as a nutritional disease that can lead to lifestyle-related diseases in the long term. Therefore, slightly changing diet and avoiding phosphorous foods could very well be relevant for others than kidney patients," said Louise Salomo.
The results have just been published in the prestigious Nephrology Dialysis – Transplantation journal. The research project was conducted in collaboration between the Department of Nephrology at Rigshospitalet and the Department of Nutrition, Exercise and Sports at the University of Copenhagen.