Preventing kidney stones is important, because such urinary stones do not always remain small and end up in the toilet bowl with the urine. Larger stones (from about 4mm) like to get stuck in the renal pelvis, in the ureter or at the entrance to the bladder, which triggers dreaded, painful renal colic.
What are kidney stones?
There are different kidney stones in terms of composition, the most common (about 75% of stones) are calcium oxalate stones. The cause of these common kidney stones may be the excessive intake of the salt oxalate through food. It is present in many foods of plant origin. The oxalic acid (oxalate) binds with calcium in the blood and the non-water-soluble calcium oxalate is formed, which can then promote the calcium oxalate stones mentioned above. Excitingly, this type of stone is very rare in developing countries and is more of a lifestyle disease of our latitudes and is due to our dietary and drinking habits.
Calcium oxalate stones and our diet
Anyone who is dealing with calcium oxalate stones and/or wants to prevent them should therefore avoid oxalate-containing foods and beverages such as peanuts, beets, rhubarb, spinach, chocolate, coffee, black tea or cocoa as much as possible. The increasingly popular traditional drink from Japan, matcha green tea made from ground green tea leaves, should also be mentioned at this point. Matcha green tea is considered, among other things, as a pick-me-up, health promoter and slimming agent. That this is actually so, prove various studies. But the drink also contains a lot of oxalic acid, so from the point of view of kidney stone formation, the consumption of matcha green tea should be moderate.
With an oxalate excretion of >0.8 mmol/day in the urine, a nutritional cause must be considered, but certain diseases can also promote the formation of calcium oxalate stones. Such as hypercalcemia or hyperparathyroidism, but also short bowel syndrome or chronic bowel disease should be excluded. Constant acidic pH values of <5.8 indicate acidosis, which promotes co-crystallization of uric acid and calcium oxalate crystals. Last but not least, it could also be a genetic over-excretion (hyperoxaluria), which, however, is usually already noticeable in children.
Now we come to the vitamin K2, which is responsible among other things for the fact that the calcium does not remain in the blood, but is stored in the bones. In this way, arteriosclerosis (deposits in the arteries) and osteoporosis (insufficient bone density, brittle bones) can be counteracted at the same time. Vitamin K1 is found mainly in the leaves of various green plants, so vitamin K1 can be absorbed through food and converted by the organism, it is believed, to the more active vitamin K2. Vitamin K2 is produced by microorganisms, including the bacteria of the intestinal flora, and can be absorbed directly through the intestinal cells. Raw sauerkraut, butter, egg yolks, liver, some cheeses, and the fermented soy product nattokinase are also sources of vitamin K2.
If we assume that vitamin K2 has a similar effect on kidney stones as it does on arteries and bones, namely that the calcium it absorbs is properly removed and utilized, we might assume that this could be a suitable nutritional approach in the fight against calcium oxalate stones. So let’s address question 2 with this assumption.
Unfortunately, current science does not currently provide anything solid on this very concrete possible connection; there are no studies on calcium oxalate stones and vitamin K2.
Therefore, for the moment, the above assumption remains. But a preventive diet with K2-containing foods in connection with the avoidance of calcium oxalate stones does not really make sense from my point of view. Many other chronic diseases would be expected in the long run.
Kidney stones and diet
However, thinking about nutrition, especially in connection with kidney stones, does of course make sense. Incidentally, the leading scientist in the field of nutrition in connection with kidney stones is Professor W. G. Robertson (Medical Research Council Leeds, UK). One of the main conclusions from his many studies is that animal proteins are one of the main risk factors for kidney stones, especially calcium oxalate stones, and free radicals are also published as a cause.
Therefore, it can be concluded that a diet as vegetarian as possible and rich in antioxidants is important. As the most important antioxidants we know vitamins C and E, vit. B complexes, provitamin A, the mineral selenium as well as secondary plant substances (polyphenols, bioflavonoids). This means that you should eat a lot of fresh, ripe, raw fruits, berries and vegetables from organic farming! Unfortunately, in this day and age such natural products are no longer widely available, which is why it is best to supplement your diet with the appropriate vital substances.