Calcium: Benefits and Sources

Our guide to calcium breaks down what this vital mineral is, how it benefits you, the best sources, and how much you really need.

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Last updated: Sep 11th, 2023
Calcium Source: Milk

From childhood, most of us have probably heard that drinking milk and getting enough calcium in our diet helps keep our bones strong and healthy. But what exactly is calcium, and what foods should we eat to ensure we’re getting enough? Our guide to calcium examines this essential mineral and delves into whether or not dairy really is the best source of calcium for preventing bone loss.

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What is calcium?

Calcium is the most abundant mineral in our bodies, and it serves many important functions. About 99% of our body’s calcium is stored in our bones and teeth (as calcium hydroxyapatite), providing structure and keeping them strong. In addition to its crucial role in bone health, calcium plays a part in muscle and blood vessel contraction and dilation, blood clotting, nerve transmission, and hormone secretion.

So how do we get the calcium we need? One way is through eating calcium-rich foods in our diet and taking calcium supplements. Some foods are better sources of absorbable calcium than others, with dairy and leafy greens at the top of the list. Supplements can be helpful if you struggle to get enough calcium in your daily diet; this can be a struggle for those following a vegan diet or those with lactose intolerance that must avoid dairy products. (Also, it’s essential to have adequate vitamin D levels in order to improve calcium absorption in your gut). Another way our body gets its calcium is by pulling from existing stores in our bones. This can happen when our blood calcium levels get too low.

Why do we need calcium?

Remarkably, our bones are constantly remodeling (breaking down and rebuilding) throughout our lifetimes, with calcium moving in and out during the process. As we age, our bone destruction slowly starts to exceed our bone production. This emphasizes the need to consume enough calcium in your youth through a healthy diet — getting adequate amounts of this essential nutrient while your body is rapidly depositing it provides a solid foundation for the future.

For women, especially, the onset of menopause and related decreased estrogen levels triggers increased bone remodeling. This, in turn, requires a greater calcium intake. And while we can’t completely prevent bone loss from happening, consuming enough calcium helps reduce the amount our body has to borrow from our bones.


Even if we get the daily recommended calcium we need, we still lose bone mass as we age. In the United States alone, an estimated 10.2 million people over age 50 have osteoporosis. Osteoporosis (which means “porous bone”) occurs when your bones break down faster than they are built. This puts you at greater risk for bone fractures. And while this condition usually doesn’t cause symptoms or pain, it can creep up on you with a sudden, painful break.

Your sex and age are the greatest risk factors for osteoporosis. Women experience rapid bone loss for the first ten years after menopause; in fact, women account for 80% of all osteoporosis cases. Your family history, ethnicity (Caucasian and Asian women are the most prone), bone structure, and weight can also play a part in your likelihood of developing bone loss. Some medical conditions and medications, such as steroids, can damage your bones when taken long-term and may lead to osteoporosis. Physicians use a bone mineral density (BMD) test to examine your bone health and whether or not you may have osteoporosis or its precursor, osteopenia.

How to prevent bone loss


Getting an adequate amount of calcium in your diet is an ideal way to help prevent bone loss. However, this can sometimes be difficult to achieve if you have certain dietary restrictions (like lactose intolerance), and your physician may recommend taking a supplement. There is some debate surrounding the best amount to ingest when targeting bone loss prevention, but research shows that calcium is best absorbed when you take 500mg or less at a time. Most calcium supplements come in the form of either calcium carbonate or calcium citrate. A supplement that includes both calcium and vitamin D is the most promising for fracture prevention. However, it’s important to note that calcium supplements may increase the risk of cardiovascular disease and kidney stones.


Regular physical activity is an excellent strategy for preventing bone loss. Weight-bearing exercises like walking, jogging, hiking, weightlifting, racquet sports, and dancing all put some strain on our bones; this triggers a response in the body to make our bones more dense. Another important consideration of physical activity is not just the direct impact it has on your bones but also the gains in muscle strength. Resistance training, even using just your own body weight, helps increase muscle mass, thereby supporting your joints and preventing falls.

It’s recommended that adults get 150 minutes of moderate-intensity exercise a week. This can be broken up into smaller segments to make your goals more attainable. Ideally, a workout routine should include balance, aerobic, and strength training exercises.

Vitamin D

Vitamin D gets a lot of attention for being an immune-boosting antioxidant, but perhaps its most critical benefit is its role in bone health. This vitamin is just as important for preventing bone loss as calcium. It works to help the body absorb and sustain calcium and phosphate levels, thereby supporting bone growth and strength. Since vitamin D is not naturally present in most foods, we typically consume vitamin D through fortified foods (like milk), supplements, and sunshine. Look for a supplement that contains at least the Recommended Dietary Allowance of 15mcg per day. Some populations may need to take more (like those with darker skin, limited sunlight exposure, or those that spend winters in the northern U.S.) to maintain adequate blood levels of vitamin D. You should always have your levels tested before supplementing, however, as there’s risk for toxicity.

Vitamin K

Vitamin K also plays a role in bone formation and is found in leafy, green vegetables. While most of the research on vitamin K has focused on K2 (found in meat, dairy, and fermented foods), having an overall vitamin K deficiency has been associated with low bone density and a higher risk of bone fractures. Most people in the United States get enough vitamin K in their diet. One or more servings a day of vitamin K-rich food, such as broccoli, kale, spinach, collard greens, dark green lettuce, or brussel sprouts, should be sufficient to meet your recommended daily allowance. Men need 120mcg of vitamin K per day, while women need 90mcg.

Vitamin A

Vitamin A is involved in the process of borrowing and redepositing calcium in bones. There are two forms of vitamin A, preformed (such as retinol) and precursor (like beta-carotene), with retinol being the active form. While vitamin A is safe when consumed within the RDA, it’s important to avoid over-supplementing retinol, as it can negatively impact your bone fracture risk if you get too much. Overall, it’s recommended that you not take more vitamin A than the RDA — 700mcg for adult women and 900mcg for adult men.

How much calcium do you need?

The amount of calcium your body needs daily depends on your age and sex. The Food and Nutrition Board of the Institute of Medicine has determined the following Recommended Daily Allowances of calcium. Entries marked with an asterisk are “Adequate Intakes” which are used when there currently isn’t enough evidence to calculate a Recommended Daily Allowance.

0-6 months200mg*200mg*
7-12 months260mg*260mg*
1-3 years700mg700mg
4-8 years1,000mg1,000mg
9-13 years1,300mg1,300mg
14-18 years1,300mg1,300mg1,300mg
19-50 years1,000mg1,000mg1,000mg
51-70 years1,000mg1,200mg
>70 years1,200mg1,200mg

What are good sources of calcium?

The best way to consume calcium is through your diet. When shopping for calcium-rich foods, take note of nutrition labels. A food with 10% or more of your daily value for calcium is a great source. Since you can only absorb so much calcium at a time, it’s a good idea to space out your calcium-rich foods, if possible. Also, while dairy gets the most attention, there are other food groups that boast strong calcium content. Those on a dairy-free diet can also benefit from fortified foods on the market. We’ve listed below some easy, healthy sources of calcium to get you started.

FoodPortion SizeCalcium
Yogurt, plain, non-fat8 ounces488mg
Yogurt, plain, low-fat8 ounces448mg
Yogurt, soy, plain8 ounces300mg
Yogurt, Greek, plain, low-fat8 ounces261mg
Milk, low-fat, 1%1 cup305mg
Milk, fat-free, skim1 cup298mg
Soy milk, unsweetened1 cup301mg
Almond milk, unsweetened1 cup442mg
Rice milk, unsweetened1 cup283mg
Collard greens, cooked1 cup268mg
Spinach, cooked1 cup245mg
Kale, cooked1 cup177mg
Tofu, raw, calcium set½ cup434mg
Salmon, canned3 ounces181mg
Sardines, canned3 ounces325mg
Orange juice, 100%, fortified1 cup349mg

The USDA also has an extensive list of foods and their calcium content available to assist you in your meal planning.

What if you’re lactose intolerant?

While dairy is a fantastic source of calcium, it’s not for everyone. The products that contain the most calcium (such as milk) also tend to contain a lot of lactose — a naturally occurring sugar found in milk and milk products. Lactose intolerance is a common problem that can lead to uncomfortable symptoms like bloating, gas, and diarrhea.

Luckily, some options are available for those that would like to consume dairy products but have an issue with lactose. You can purchase a lactase enzyme supplement (such as Lactaid) and take it with your food to help break down the lactose you consume or choose dairy products that already contain lactase in them. These products are readily available at most grocery stores.



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