Will drinking milk cause kidney stones?

Drinking milk is something that many people do in their daily lives. Many people are also afraid of drinking milk because milk is rich in calcium. If they drink milk frequently, many people are afraid that it will cause kidney stones. In fact, drinking milk does not necessarily cause kidney stones. As long as you drink milk in the correct way, drinking milk will only benefit the human body and will not cause any other harm!

1. Calcium intake does not mean stones

The occurrence of kidney stones is related to many factors such as abnormal metabolism in the body, urinary tract infection, and drug effects. It is somewhat one-sided to attribute the cause of stones entirely to eating habits.

In fact, the factors that cause calcium stones are very complex. Even if we consume excessive amounts of calcium, it does not mean that the same amount of calcium ions will be absorbed. When our body finds that excessive calcium ions are absorbed and cause increased blood calcium, it will reduce calcium absorption through negative feedback of intestinal 1-25-dihydroxyvitamin D3. Of course, transient hypercalciuria may occur at this time.

2. Oxalate ions are the cause of stone formation

Compared with calcium ions, oxalate ions are a more important factor in stone formation.

The vegetables and fruits we eat on a daily basis are rich in oxalic acid, including vitamin C, which is also a precursor of oxalic acid. When fruits and vegetables are eaten, there are more oxalate radicals in the intestines. Only soluble oxalate can be absorbed by the intestines and eventually excreted through the kidneys to form oxaluria.

When the concentration of oxalic acid in urine is too high, it is very easy to combine with calcium ions in urine to form calcium oxalate crystals, which is the early form of calcium oxalate stones.

Oxalic acid, as an anion, combines with cations such as sodium, potassium, and magnesium to form soluble oxalates, which can be absorbed. However, calcium ions in the intestine combine with oxalic acid to form insoluble calcium oxalate, which cannot be absorbed and is ultimately excreted from the body through the intestine.

3. Drinking milk can kill two birds with one stone

Doctors often encourage patients with stones to drink more milk because the calcium absorbed from milk is relatively stable, and the unabsorbed calcium can combine with oxalate ions in the intestines to form stable calcium oxalate that is not easily absorbed and decomposed, and is excreted through the intestines, effectively reducing the oxalic acid content in the urine.

Regarding drinking milk, there is no need for ordinary people, including most stone patients, to impose too many restrictions. Even for patients with uric acid stones, it is fine as long as they consume it appropriately. For some patients with calcium stones, they can even be encouraged to drink more milk. However, there is a special type of stone patients. Patients with cystine stones have problems with protein conversion in the body due to genetic reasons, and their milk intake needs to be strictly limited.