If you are a patient with calcium oxalate kidney stones, you have probably read or been told that you should reduce (or eliminate) calcium from your diet. Makes sense, right? And one of the first foods affected is milk, but also yogurt, cheese, shrimp, and prawns. Damn, prawns are so good!
But is this really true, or is it a myth? Keep reading to learn more about the impact of milk on kidney stones.
What is calcium? And how does it contribute to kidney stone formation?
Calcium is one of the most important minerals for our body and the most abundant. Almost all calcium is stored in our bones and teeth. And our body uses it to perform many vital functions such as muscle contraction, sending signals through the nervous system, improving blood circulation, or releasing hormones.
Despite its enormous benefits, calcium has a bad reputation among patients (and also among doctors) due to some erroneous assumptions about its role in the formation of calcium oxalate kidney stones.
Does this mean I should stop drinking milk?
No! In fact, as researchers from Harvard University demonstrated (Curhan, Willett, Rimm, & Stampfer, 1993), calcium intake reduces the risk of forming kidney stones.
This study has since been replicated by other authors who have confirmed the findings, and today, the Clinical Guidelines for Urolithiasis, which represent the consensus of all urologists treating kidney stones, recommend normal calcium consumption as a measure to prevent the formation of calcium oxalate stones.
But how can calcium help prevent stone formation?
Calcium oxalate stones are usually formed by an excess of oxalate in the urine. This oxalate is usually obtained from the intake of foods rich in oxalates such as spinach, tomato, tea, or chocolate.
When consuming milk (or other dairy products), calcium binds to oxalate in the intestine, forming a complex that cannot be absorbed by the body and is eliminated in the feces. In this way, calcium consumption reduces the amount of oxalate that is absorbed and then reaches the urine. Less oxalate in the urine means fewer calcium oxalate stones. Easy!
Therefore, when you eat products with a high oxalate content, a good recommendation is to accompany them with a calcium-rich food. For example, if you really like chocolate, try to accompany it with a glass of milk whenever you can. This way you will reduce the risk of forming stones.
So, what is the recommended amount of calcium? How much is that in liters of milk?
According to the National Institutes of Health of the United States, the recommended daily amount of calcium depends on your age and sex (see Table), but generally, it is recommended to consume 1,000 mg of calcium per day.
| Life Stage | Recommended Amount |
| Infants up to 6 months | 200 mg |
| Infants 7 to 12 months | 260 mg |
| Children 1 to 3 years | 700 mg |
| Children 4 to 8 years | 1000 mg |
| Children 9 to 13 years | 1300 mg |
| Adolescents 14 to 18 years | 1300 mg |
| Adults 19 to 50 years | 1000 mg |
| Adult men 51 to 70 years | 1000 mg |
| Adult women 51 to 70 years | 1200 mg |
| Adults over 71 years | 1200 mg |
| Pregnant and lactating adolescents | 1300 mg |
| Pregnant and lactating adults | 1000 mg |
And how much is that? Well, to give you an idea, every time you drink a glass of milk, you are consuming about 300 mg of calcium, which is 30% of the recommended daily amount. Not bad, right? Seen this way, consuming calcium doesn't seem so difficult.
I am vegan and don't like milk, what can I do to consume the calcium I need?
If you are vegan or simply don't like milk, you can also consume calcium from other plant sources such as seeds or nuts. For example, 100 g of sesame seeds or 400 g of almonds provide the 1,000 mg of calcium you need daily.
You can also take calcium supplements, but never do so without medical recommendation.
In any case, if you want to prevent calcium oxalate stones, it is best to follow a balanced diet with low oxalate intake, normal calcium intake, and supplement with products containing phytate; a clinically validated ingredient to inhibit the crystallization of this type of stone.
In conclusion
Calcium is a very important mineral for your body that also helps prevent stone formation. Consume 1,000 mg of calcium daily from milk or other calcium-rich foods. And if you want to be even more sure to prevent calcium oxalate stones, supplement your diet with Lit-Control® pH Balance.
References
Curhan, G., Willett, W., Rimm, E., & Stampfer, M. (1993). A Prospective Study of Dietary Calcium and Other Nutrients and the Risk of Symtomatic Kidney Stones. The New England Journal of Medicine.
