No doubt about it, eating enough calcium is a critical part of a healthy diet for people who have calcium kidney stones. But, what is the best way to eat enough calcium?
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Why Is Calcium So Important?
Block Oxalate Absorption
It may seem counterintuitive to eat MORE calcium when you have calcium kidney stones. But, hear me out.
The first reason eating enough calcium is so important is to reduce how much oxalate is absorbed. (1)
Calcium loves to bind with oxalate – this is why it is the most common type of kidney stone. We can use that love to our advantage by pairing high calcium foods with meals. When calcium is eaten with healthy meals that have oxalate in them, calcium will bind with oxalate in the intestine. Bound oxalate cannot get absorbed into the body. In turn, this will reduce the amount of oxalate in our urine and reduce the risk of kidney stones.
Protect Your Bones
The second reason calcium is so important for people with calcium kidney stones is bone health. People who have calcium kidney stones are at greater risk of bone fractures and weak bones. (2)
Eating enough calcium and vitamin D can help keep bones healthy and strong.
How Much Calcium Do I Need?
People with calcium kidney stones need the same amount of calcium as the general population. It is just even more important that people with calcium kidney stones meet their calcium goals!
One serving of dairy has 200-300mg of calcium. Ideally, eat one serving of dairy with 3 meals per day. These 3 servings of dairy, combined with small amounts of calcium from other foods, is a good way to be pretty sure you are eating enough calcium.
One serving of dairy is:
- 1 cup of milk or kefir
- 3/4 cup of yogurt or low-sodium cottage cheese
- 1 ounce of cheese – look for lower sodium cheeses like goat, mozzarella or Swiss
I’ve written a cookbook that includes dairy in all the recipes. I know that drinking milk with every meal can get boring!
Cow’s Milk Dairy First
When at all possible, I recommend cow’s milk dairy for people who have calcium kidney stones. Cow’s milk and dairy are, by far, the most calcium dense foods. And, dairy has lowered kidney stone risk in studies.(5)
If you have kidney disease in addition to kidney stones, the best milk for you might be different.
Skim vs. Whole Milk
The amount of fat in milk has little effect on the calcium amount. Skim, 1%, 2% and whole milk have basically the same amount of calcium.
The one exception is dairy with a very high fat content. Foods like cream, cream cheese and sour cream are much lower in calcium.
Of course, the higher the fat content, the higher the calories and fat. For most people, I recommend fat-free or low-fat dairy.
Tips for Lactose Intolerance
The most common reason for milk intolerance is difficulty digesting lactose. Lactose is a sugar found in dairy. We need an enzyme called lactase to digest lactose. Without enough lactase, dairy can cause gas, diarrhea, cramping and other uncomfortable symptoms.
The good news is that you can train your body make lactase again! Rather than dive in with 3 servings of dairy per day, start with just one (or even a half!) serving each day. Assess your symptoms for a few weeks and go up from there.
Start with Cheese or Yogurt
Cheese and yogurt tend to have less lactose in them. People who cannot tolerate milk often can tolerate cheese or yogurt.
Try Low Lactose Milk
Lactaid* and other lactose free dairy is a great option for people who have kidney stones.
You can also try Lactaid* in pill form when you eat dairy.
Good Non-Dairy Calcium Sources for Kidney Stones
Of course, milk is not for everyone. Many people avoid dairy due to cultural, religious, ethical or environmental reasons.
Most plant-based and non-dairy milk substitutes are supplemented with calcium. Because we know that calcium supplements tend to increase urine calcium more than natural sources, this is somewhat of a concern. However, no research has investigated the difference in urine calcium after consumption of natural and calcium supplemented foods.
Some calcium is certainly better than no calcium. Calcium from both dairy and non-dairy sources has been shown to reduce the risk of kidney stones.(9)
For people with a history of calcium kidney stones, dairy substitutes made from these milks are good choices.
- Rice Milk
- Oat Milk
- Coconut Milk
- Hemp Milk
- Pea Milk
Double check that the brand you buy is supplemented with calcium.
Dairy Substitutes NOT Recommended for Kidney Stones
These dairy substitutes are made from foods high in oxalate. Because oxalate is water soluble, it is a fair assumption that any liquid made from these foods will contain oxalate.
Although not everyone with kidney stones needs to avoid oxalate, I would recommend steering clear of these options. Adding these milk substitutes 3 times per day could add a very large oxalate load.
I do not recommend these milk substitutes for people with calcium kidney stones:
- Almond Milk
- Cashew Milk
- Soy Milk
Calcium From Plant Sources
Some plant foods are surprisingly high in calcium! These foods all have at least 60mg of calcium per serving (1 cup unless otherwise specified):
- Collard greens
- Broccoli rabe
- Chia seeds (2 tablespoons)
- Sunflower seeds (1/4 cup)
Italicized foods are higher in oxalate and not recommended for people with high urine oxalate levels.
However, the amount of calcium in most of these foods is still far less than dairy.
Importantly, calcium from these plant foods is not absorbed as well compared to dairy. Many of these foods are high in oxalate. Calcium is already bound to oxalate (and other compounds called “phytates“), which reduces absorption. In addition, because calcium is already found to oxalate, it will not do as good a job of binding other oxalate in that meal.
However, eating lots of fruits and vegetables is critical for kidney stone prevention.(1) Including some high calcium veggies can absolutely help get your to our daily goal of 1,000 – 1,200mg of calcium.
Many patients ask “why can’t I just take a calcium supplement?”. Although this may seem like an easy fix, calcium supplements are not always the best choice for people with kidney stones.
The concern with calcium supplements is that supplemental calcium is much more likely to raise urine calcium than calcium that naturally occurs in food. This is very problematic for kidney stone formers because high urine calcium is the most common cause of calcium kidney stones.(1)
However, calcium supplements may be warranted in some people with kidney stones. Especially if urine calcium is normal. Work with your doctor to figure out what is best for you.