Last week, we talked about oxalate swaps. This week, let’s talk about calcium—especially for people who cannot tolerate dairy, choose not to eat it, or follow a vegan diet.
Kidney stone patients often become afraid of calcium because calcium is in the name of the most common type of kidney stone. But calcium is not the enemy.
We need calcium to protect our bones. We also need calcium with meals because it binds with oxalate in the digestive tract. This helps prevent some of that oxalate from being absorbed and eventually reaching the urine.
The goal is not to avoid calcium. The goal is to find calcium-rich foods that work for you and include them throughout the day.
How Much Calcium Do You Need?
Most adult men and women who still get a menstrual period need approximately 1,000 mg of calcium per day.
Most women who no longer get a menstrual period need approximately 1,200 mg per day. Some older men may also need 1,200 mg.
Your doctor may recommend a different amount based on your age, bone health, medications, medical history, or individual needs. Consult with them if you are unsure.
Get Your Calcium From Food
Whenever possible, we want calcium to come from foods and beverages rather than pills. This is important for everyone—not only kidney stone patients.
Most of the calcium in the body is stored in our bones. When we consistently fall short, the body still has to maintain the calcium level it needs in the blood. Over time, inadequate calcium intake can contribute to weaker bones.
Kidney stone prevention is not only about protecting your kidneys. We must protect your bones, too.
Some people need calcium supplements for a specific medical reason, such as osteoporosis, malabsorption, bariatric surgery, bowel disease, or another condition that makes it difficult to get or absorb enough calcium from food. If your doctor prescribed a calcium supplement for a specific medical reason, do not stop taking it without speaking with them.
However, many kidney stone patients tell me they were instructed to take a calcium supplement without being given a specific medical reason. If this happens, tell your doctor that you are a kidney stone former and ask whether you can meet your calcium needs through food instead.
You might say:
“I am a kidney stone former, and I would prefer to get my calcium from food when possible. Is there a medical reason I need a calcium supplement?”
If you do not have a condition that prevents you from getting or absorbing enough calcium from food, food sources are generally the best place to start. They allow you to spread calcium throughout the day and include it with meals, where it can bind with oxalate in the digestive tract.
The point is not that calcium supplements are always wrong. The point is that they should not automatically replace calcium-rich foods when you can safely and realistically meet your calcium needs through food.
Fortified Plant Milk Is Not the Same as a Calcium Pill
Patients often ask why I recommend calcium-fortified plant milk when I generally prefer that they not take calcium pills unless medically necessary.
Although the calcium in plant milk has been added during manufacturing, it is still consumed as a food or beverage. When you drink it with a meal, that calcium is present in the digestive tract at the same time as the oxalate in your food. This gives the calcium and oxalate a chance to bind before the oxalate is absorbed.
A calcium pill delivers a concentrated dose. If it is taken between meals or at bedtime, the calcium may not be present when the oxalate from your food arrives.
You can read more about the difference here:
Choose Calcium Sources That Actually Make a Difference
Many foods contain a little calcium. That does not necessarily make them useful sources of calcium.
You should not have to combine 25 different foods or eat enormous portions to meet your daily goal. Instead, choose two or three dependable foods or beverages that provide a meaningful amount of calcium.
A strong calcium source will often provide approximately 250 to 400 mg per serving. Always check the Nutrition Facts label because calcium amounts can vary greatly from one brand to another.
Swap Unfortified Plant Milk for Calcium-Fortified Plant Milk
Unsweetened calcium-fortified plant milk can be one of the easiest ways to get a meaningful amount of calcium without dairy.
Good options include oat, pea, macadamia, and flax milk. Choose a product with zero grams of added sugar and approximately 300 mg or more of calcium per cup.
Do not assume every plant milk is calcium-rich. Some provide 300 to 450 mg per cup, while others provide very little.
Shake the container well before pouring because the added calcium can settle at the bottom.
Almond and cashew milk are not included in my recommendations because almonds are extremely high in oxalate.
Swap Sweetened Nondairy Yogurt for Unsweetened Fortified Yogurt
Calcium-fortified nondairy yogurt can be another useful vegan option.
Choose one with zero grams of added sugar and ideally at least 200 to 300 mg of calcium per serving. Make sure the listed serving size is an amount you will realistically eat.
Many nondairy yogurts sound healthy but provide very little calcium. Others contain a surprising amount of added sugar. Ignore the health halo on the front of the container and turn it around to read the Nutrition Facts label.
Swap Regular Orange Juice for Calcium-Fortified Orange Juice
Calcium-fortified orange juice may provide approximately 300 to 350 mg of calcium per cup.
Choose one with calcium added and zero grams of added sugar. Remember that orange juice naturally contains fruit sugar, even when the label shows no added sugar. Because juice can raise blood sugar quickly, this may not be the best choice for someone with diabetes, prediabetes, or difficulty managing blood sugar. When it is an appropriate option, have it with a meal rather than sipping it throughout the day.
Swap Regular Dairy for Lactose-Free Dairy
Some people who believe they cannot tolerate dairy are actually having difficulty digesting lactose.
Lactose-free dairy still provides the calcium and protein found in regular dairy. The lactose has been broken down to make it easier to digest.
Lactose-free milk, plain lactose-free yogurt, and plain lactose-free kefir can all be excellent options. Choose products with zero grams of added sugar.
Lactose-free does not mean sugar-free. The Nutrition Facts label may still show total sugar because milk naturally contains sugar. Look specifically at the separate added sugars line.
Swap Flavored Yogurt for Plain Yogurt
For those who tolerate dairy, plain yogurt remains an excellent source of calcium. And protein (look at label) for non-meat eaters.
Traditional plain yogurt, Greek yogurt, lactose-free yogurt, and calcium-fortified nondairy yogurt can all work. Traditional yogurt often contains more calcium than Greek yogurt because some calcium is lost during the straining process.
That does not make Greek yogurt a poor choice. It simply means you need to check the label rather than assume every yogurt provides the same amount.
Choose a product with zero grams of added sugar. You can add your own fruit, cinnamon, or preferred sweetener if desired.
Swap Sweetened Kefir for Plain Kefir
Plain kefir can provide several hundred milligrams of calcium per serving, along with protein and live cultures. I use this in my bowl of berries every night! It’s good for gut health too, because it is fermented.
Choose plain dairy kefir or plain lactose-free kefir with zero grams of added sugar. Flavored kefir can contain a surprising amount of added sugar, so plain is usually the better everyday choice. Use berries to add some natural sugar and fiber!
Swap Salty Cheese for a Lower-Sodium Cheese
Cheese can provide a meaningful amount of calcium, but it can also provide far too much sodium.
Swiss cheese is often one of the best lower-sodium choices. Look for a cheese that provides a good amount of calcium while containing approximately 125 mg of sodium or less per slice or serving.
Some fresh mozzarella, reduced-sodium cheeses, and farmer cheeses may also work, depending on the brand. Farmer cheese can be lower in sodium, but some varieties contain very little calcium.
Check both the calcium and sodium before buying. A food is not automatically a useful calcium source simply because it is cheese. This is a common misconception among the patients I work with every day.
Vegan Option: Calcium-Set Tofu
Calcium-set tofu can provide a substantial amount of calcium.
Look for calcium sulfate in the ingredient list, and then check the Nutrition Facts label. The calcium content varies widely by product.
Tofu can contain more oxalate than many of the other calcium sources listed here, so portion size and your individual 24-hour urine results still matter. It does not automatically need to be removed from every kidney stone diet, but it should not be treated as an unlimited food.
Fish With Edible Bones
For people who eat fish, sardines and canned salmon with the bones can provide a meaningful amount of calcium. The bones are soft and edible.
Sardines with bones may provide approximately 300 mg of calcium in a 3-ounce serving, while canned salmon with bones may provide approximately 180 mg in a 3-ounce serving.
Canned fish can also be high in sodium, so compare labels carefully and choose the lowest-sodium option you can find. It may not be the best choice for someone following a very low-sodium diet unless an appropriate product is available.
Lower-Oxalate Vegetables Can Contribute Calcium
Certain lower-oxalate vegetables can contribute calcium, especially for people who want more plant-based choices.
Kale and bok choy are among the better options, although the exact amount depends on the serving size and whether the vegetable is raw or cooked. Broccoli contributes much less. One-half cup of cooked broccoli provides only about 30 mg of calcium.
These vegetables are nutritious and can add to your daily calcium intake, but they should generally be supporting players rather than your primary calcium sources.
I do not want you eating enormous bowls of vegetables several times a day trying to reach 1,000 or 1,200 mg of calcium. Use vegetables to contribute calcium, but rely on more concentrated sources—such as fortified plant milk, fortified nondairy yogurt, dairy or lactose-free dairy, kefir, or lower-sodium cheese—to provide most of what you need.
Spinach is not a useful calcium source for kidney stone patients. Although it contains calcium on paper, it is extremely high in oxalate, and much of that calcium is not available for the body to absorb.
A Simple Dairy-Free Calcium Day
You do not need to combine 25 different foods to reach your calcium goal.
At breakfast, you might have one cup of unsweetened calcium-fortified pea, oat, macadamia, or flax milk. Depending on the brand, that may provide approximately 300 to 450 mg of calcium.
At lunch, you could include one serving of unsweetened, calcium-fortified nondairy yogurt, which provides approximately 200 to 300 mg.
At dinner, include a lower-oxalate vegetable to contribute some additional calcium.
An additional cup of calcium-fortified plant milk with another meal may provide another 300 to 450 mg.
Depending on the products selected, this simple plan could provide approximately 800 to 1,200 mg of calcium, with vegetables and other foods contributing the rest.
The exact amounts matter, so always check your labels.
What to Check on the Label
Before buying a calcium-rich product, check four things: the serving size, calcium, added sugar, and sodium.
For plant milk, nondairy yogurt, dairy yogurt, and kefir, choose products with zero grams of added sugar. For cheese and canned fish, pay close attention to sodium.
Do not rely on words such as “fortified”, “healthy”, or “plant-based” on the front of the package. Those words do not tell you whether the product contains enough calcium.
Oh, By the Way! Understanding the Calcium Percentage
Most Nutrition Facts labels show the actual milligrams of calcium beside the percentage. Use the milligram number whenever it is available. It is the easiest way to know exactly how much calcium you are getting.
If the label shows only a percentage, multiply that number by 13:
- 10% calcium = 130 mg
- 20% calcium = 260 mg
- 25% calcium = 325 mg
- 30% calcium = 390 mg
Always check the serving size first because the calcium amount applies to one serving.
Here is the part that confuses many people: the calcium percentage on a Nutrition Facts label is based on the FDA’s standard Daily Value of 1,300 mg. That does not mean everyone needs to consume 1,300 mg of calcium every day.
The FDA uses one standard number to keep food labels consistent and make products easier to compare. Your personal calcium goal may still be 1,000 or 1,200 mg per day.
The label number is a labeling tool—not a new recommendation for your body. Do not worry if reaching your personal calcium goal does not add up to 100% on the Nutrition Facts label.
Have Calcium With Your Meals
Try to spread your calcium throughout the day and include a calcium-rich food or beverage with your meals.
This places calcium in the digestive tract at the same time as the oxalate in your food, where the two can bind.
A simple approach is to include one meaningful calcium source at breakfast, lunch, and dinner. You do not need to reach your entire calcium goal in one sitting. In fact, I would like you to space out your calcium intake throughout the day and no more than 500 mg at any one time. The body only absorbs so much at once, and the rest will wind up in your urine.
The Bottom Line
You do not need dairy to get enough calcium, but you do need a plan.
Choose two or three dependable calcium-rich foods or beverages that fit your needs. Make sure they provide a meaningful amount of calcium—not just a little.
Calcium-fortified oat, pea, macadamia, or flax milk; fortified nondairy yogurt; calcium-fortified orange juice for those without blood sugar concerns; lactose-free dairy; plain yogurt; plain kefir; lower-sodium cheese; calcium-set tofu; fish with edible bones; and selected lower-oxalate vegetables can all play a role.
Choose products with the lowest grams of added sugar.
Whenever possible, get your calcium from foods and beverages rather than pills. Calcium helps protect your bones, and calcium eaten with meals helps reduce the amount of oxalate that reaches your urine.
The best calcium source is one that provides enough calcium, fits your health needs, and is something you will use consistently.
Your friend,
Nurse Jill
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