What Is Calcium?
Calcium is a mineral that’s well-known for its key role in bone health. Calcium also helps maintain heart rhythm, muscle function, and more. Because of its health benefits, calcium is one of the best-selling supplements in the U.S.
Your body is abundant in calcium. Around 99% of this mineral is stored in your bones and teeth, and 1% is in your blood and soft tissues.
Eating calcium-rich foods is important for growing and keeping bones strong. It’s also an important nutrient for healthy cell function. Your body needs calcium to support muscle and nerve function, regulate blood pressure and hormone levels, and help with communication between cells.
Calcium Health Benefits
Calcium has many uses. It's an ingredient in antacids, and doctors use it to control high levels of magnesium, phosphorus, and potassium in your blood.
It may also ease premenstrual syndrome (PMS) symptoms and help prevent certain cancers. Some research shows that calcium with vitamin D may help protect premenopausal women from breast cancer.
Further, calcium serves as an important nutrient for:
Cellular function. Your body maintains a certain level of calcium in your blood at all times so that your cells can work properly. A dip in calcium blood levels will signal your body to borrow calcium from your bones.
Bone health. Your bones continually break down and rebuild. You can get osteoporosis when there's an imbalance between bone building and bone breakdown. Before age 30, you build bone at a faster rate than you break it down. After age 30, the rates reverse. This is why older people have more brittle bones that are at a higher risk of breaking.
One way to prevent bone loss after age 30 is by getting enough calcium, which reduces the amount your body takes from your bones. Calcium supplements are standard for treating and preventing osteoporosis and the condition that often comes before it, osteopenia (loss of bone density).
Blood pressure control. Calcium helps blood vessels contract and relax, so you need it to maintain healthy blood pressure.
Decreased risk of kidney stones. Calcium also prevents kidney stones from forming by decreasing your body's absorption of oxalates, which are found in many foods such as spinach, beets, raspberries, and sweet potatoes. Oxalates are linked to a higher risk of kidney stones. Only calcium from food — not supplements — can help reduce this risk.
Calcium and Vitamin D
Calcium and vitamin D have a close relationship. Your body needs vitamin D to absorb calcium properly in your gut and keep enough calcium in your bloodstream. Some foods, such as salmon and cheddar cheese, have both vitamin D and calcium.
Calcium Dosage
The U.S. Food and Nutrition Board has set dietary reference intake (DRI) and recommended daily allowance (RDA) standards for calcium. Getting this amount from calcium-rich foods, with or without supplements, may be enough to keep your bones healthy. Doctors may suggest higher doses.
Category | Calcium (RDA) |
| 0-6 months | 200 milligrams/day |
| 7-12 months | 260 milligrams/day |
| 1-3 years | 700 milligrams/day |
| 4-8 years | 1,000 milligrams/day |
| 9-18 years | 1,300 milligrams/day |
| 19-50 years | 1,000 milligrams/day |
| 51-70 years | 1,200 milligrams/day for women; 1,000 for men |
| 70+ years | 1,200 milligrams/day |
A supplement's tolerable upper intake levels (ULs) are the highest amount that most people can take safely. For calcium, they are:
- Infants 0-6 months: 1,000 milligrams/day
- Infants 7-12 months: 1,500 milligrams/day
- Children 1-8 years: 2,500 milligrams/day
- Children/teens 9-18 years: 3,000 milligrams/day
- Adults 19-50 years: 2,500 milligrams/day
- Adults over 51 years: 2,000 milligrams/day
In general, it's best to take calcium supplements with food. Don't take more than 500 milligrams at one time for better absorption. Split up larger doses over the course of the day. You must also get enough vitamin D and magnesium for your body to use calcium properly.
Calcium-Rich Foods
While many supplements are available, scientists recommend that at least half of your calcium intake come from your diet. These five foods are some of the best sources of calcium:
Dairy products. Products such as milk, yogurt, and cheese are rich in calcium and tend to be the best-absorbed sources. Your body doesn't absorb calcium as well from plant-based foods.
Calcium-fortified foods. Cereals are often fortified with calcium. Some fortified cereals provide as much as 100 milligrams of calcium per serving.
Canned salmon. Aside from dairy products, canned salmon is one of the best dietary sources of calcium. Just 3 ounces of canned salmon provides 181 milligrams. Salmon also contains vitamin D, which helps your body absorb more calcium.
Flour tortillas. Good news for carb lovers: one 10-inch flour tortilla provides 90 milligrams of calcium.
Canned baked beans. A half cup of canned baked beans has almost 60 milligrams of calcium. Beans also contain a lot of fiber.
Nondairy sources of calcium
Figs. Dried figs are a healthy, sweet, and calcium-dense snack. Two figs contain about 27 milligrams of calcium. This fruit is a natural sweetener and a healthier alternative to refined sugars.
Dark green, leafy vegetables. Cooked kale, spinach, and collard greens are all good calcium sources. Surprisingly, cooked kale has more calcium per serving than milk, at 177 milligrams per cup. This versatile leafy green also fights against heart disease, cancer, and inflammation.
Cooked collard greens have the highest amount: a cup provides 268 milligrams of calcium.
Soybeans. Foods made from soybeans are excellent sources of calcium. Some soy products include:
- Edamame
- Tofu
- Miso
- Soy milk
- Tempeh
One cup of dry-roasted soybeans has 130 milligrams of calcium, making them an excellent source for those who follow a vegan diet.
Bok choy. Also called white cabbage, Chinese cabbage, or pak-choi, it has about 74 milligrams of calcium in every cup.
Bok choy is also packed with vitamin A and vitamin C. One cup of this cooked leafy green provides more than 40% of the RDA for vitamin A and almost two-thirds for vitamin C.
Broccoli. A cup of raw broccoli has about 35 milligrams of calcium. The same amount of cooked broccoli contains 76 milligrams.
Oranges. One whole orange has around 60 milligrams of calcium, making it one of the most calcium-rich fruits.
You can pick up calcium-fortified orange juice at the grocery store for an added mineral boost. Calcium citrate malate is a well-absorbed form found in some fortified juices.
Seeds. While many seeds are excellent sources of calcium, the winners are poppy, pumpkin, sesame, celery, and chia seeds.
Two tablespoons of chia seeds contain about 14% of your RDA of calcium.
Winged beans. Winged beans, or goa beans, grow in humid, tropical countries. A 44-gram serving provides more than 4% of the recommended daily value of calcium.
If you're lactose intolerant or vegan, you may not get enough calcium from your diet, as dairy products are one of the most common sources of calcium.
Almonds. Nuts, including almonds, are another good source of nondairy calcium. A 30-gram serving provides about 75 milligrams of calcium.
Whey protein. One hundred grams of whey protein has 485 milligrams of calcium.
Calcium Supplements
You may want to talk to your doctor about calcium supplements and the best way to take them if you:
- Follow a vegan diet
- Can’t digest lactose (you’re lactose intolerant)
- Eat or drink a lot of protein or sodium, which can cause your body to lose more calcium
- Have thin, weak bones (osteoporosis)
- Take long-term corticosteroid treatments
- Have bowel or digestive diseases and can’t absorb calcium well
Calcium Risks
Studies suggest that calcium supplements may have some unwanted effects:
Side effects. At normal doses, calcium supplements may cause bloating, gas, and constipation. Very high doses of calcium can lead to kidney stones. Some studies show that taking calcium supplements in addition to a diet high in calcium could raise your risk of heart attacks and strokes. But we need more research.
Interactions. If you take any prescription or over-the-counter medicines regularly, ask your doctor if it's safe to use calcium supplements. Calcium can interact with drugs for heart disease, diabetes, epilepsy, and other conditions. High doses of vitamin D can result in dangerously high levels of calcium. High doses of calcium can also prevent your body from absorbing minerals such as iron and zinc. In general, take calcium 1 to 2 hours apart from other supplements or medications. If you take them at the same time, calcium can bind to those products, and they’ll pass from your body without being absorbed.
Other forms of calcium. There’s no need to use products known as "coral calcium." Claims made that coral calcium is better than regular calcium are unproven. Also, coral calcium products may have dangerous amounts of lead.
Risks. If you have kidney disease, heart problems, sarcoidosis, or bone tumors, ask your doctor before you take calcium supplements.
Overdose. High levels of calcium in your blood can cause nausea, dry mouth, belly pain, an irregular heartbeat, confusion, and death.
Calcium and Pregnancy
During pregnancy, your baby gets calcium from you through the placenta. The amount of calcium transferred rises as your pregnancy progresses, reaching its peak at 35 weeks. That's why it's essential to continue getting calcium during pregnancy. The World Health Organization (WHO) suggests pregnant people get 1,200 milligrams of calcium a day.
Takeaways
Calcium is a mineral crucial for bone health, muscle function, and more. Most of it is stored in your bones and teeth, but a small portion is in your blood and tissues. Calcium supplements are popular, but recent studies suggest that some benefits are best gained from food sources such as dairy products and calcium-fortified foods rather than supplements. Suggestions for how much calcium you should get vary by age and life stage.
