Did you know that there are differences in the type of phosphate? In this article, you'll learn why you need to be careful with phosphate in some foods, while you can turn a blind eye to others.
Phosphate & dialysis basics
Phosphorus is a chemical element found in almost all foods as phosphate. When you eat something, the phosphate is absorbed by the body in your intestines. In people with functioning kidneys, the kidneys regulate the level of phosphate in the body. This means that they filter any excess out of the blood and excrete it. With kidney disease, this no longer works so well, which is why there is a risk of excess phosphate.
Your doctor therefore regularly tells you as a dialysis patient that you should eat little phosphate and not forget your phosphate binders. They have their reasons to push you so much because too much phosphate in your body leads to dangerous calcium deposits in your blood vessels (=arteriosclerosis).
Different phosphate groups
It is interesting that there are different groups of phosphate. Simply put, the body can use phosphate from animal products better than from plant products. Very specifically, phosphate can be divided into three groups:
1. Plant-based phosphate (30-50% bioavailability)
This is found in nuts, grains and legumes (e.g. lentils, beans, chickpeas) for example. Plant-based phosphate cannot be absorbed so well by the human intestine. Therefore, we speak of low bioavailability. This is actually good for you as a dialysis patient, because it means that more than half of the phosphate you take in does not get into your blood, but remains in your intestine and is directly excreted again. An exception to this rule is sourdough, which releases phosphate from its compound as it germinates, allowing more to enter the bloodstream. That's why you should rather eat yeast dough products.
Animal-based phosphate (40-60% bioavailability):
Where there is a lot of protein, there is a lot of phosphate. You can basically remember this for foods such as milk, cheese, eggs, fish, meat and sausages. This type of phosphate is also called organic phosphate. It is absorbed slowly, but better than plant-based phosphate - about 40-60%. Therefore, you should be careful that the total amount of animal phosphate you eat is not too high in the long run.
3. Phosphate in food additives (up to 100% bioavailability)
Your biggest enemy in the fight against too much phosphate are additives. Many industrially processed foods contain them to extend their shelf life or enhance flavor. In the EU, these have to be labelled with so-called E-numbers on packaging (e.g. E338, E1413, etc.). Why are these E-numbers so dangerous? On the one hand, the dose of the additives is not indicated on the packaging. There tends to be a lot of it in processed products. On the other hand, almost 100% of this phosphate can be absorbed by your body. Even though not all E-numbers contain phosphate (or potassium), you should always stay away from products with E-numbers. You can find more information about additives in other articles in the Mizu app.
What and how much phosphate can I eat now?
You might be asking yourself what all this means for your diet. Simply summarized, you can say that vegetable phosphate is half as bad, you should be a little careful with animal phosphate and keep your hands off additives if possible.
Basically, your daily guideline depends on how high your blood phosphate level is. This should be measured in your dialysis center at least four times per year. There are also international guidelines that have researched and calculated recommendations for the optimal amount of phosphate for dialysis from long-term studies. It is important to discuss your daily guideline amount of phosphate with your nephrologist and a nutritionist, who is familiar with dialysis. They know your health situation and nutritional requirements best and are as interested as you are in keeping your phosphate levels in the target range.
