Although they don't provide as much bone-building calcium as dairy products or leafy greens, citrus fruits are rich in nutrients and decent sources of calcium. Calcium supplements made from citric acid can also help you add more calcium to your diet. Oranges contain the most calcium compared with other whole citrus fruits, and calcium-fortified orange juice can provide a significant amount of dietary calcium.
Significance
Calcium is an important mineral for maintaining overall health and bone health in particular. Getting enough dietary calcium can prevent age-related bone loss that leads to osteoporosis, a condition in which bones are so weak that they break easily. Many people don't get enough calcium in their diet, especially adolescent girls and post-menopausal women. Vegetarians who avoid dairy products, people with eating disorders and lactose-intolerant individuals are also at risk for having insufficient calcium status. According to the National Institutes of Health, or NIH, adults ages 19 to 51 need 1,000 mg of calcium daily, while women ages 51 and older need 1,200 mg, and children ages 9 to 18 need 1,300 mg of calcium per day.
Calcium in Common Citrus Fruits
Citrus fruits are not a significant source of dietary calcium but if eaten as part of a varied diet containing other calcium-rich foods, they can help you meet your daily calcium intake requirements. Oranges contain more calcium than other citrus fruits, offering up 52 mg per medium-sized fruit, according to the USDA's National Nutrient Database. The calcium contents for other common citrus fruits are as follows: tangerines, 33 mg per fruit; limes, 22 mg per fruit; lemons, 15 mg per fruit; and grapefruits, 15 mg per fruit. Some citrus products, namely juices, are also fortified with calcium. One cup of calcium-fortified orange juice contains 500 mg of calcium, per USDA figures.
Comparison
While oranges contain more calcium than other fruits, dairy foods and some fish and vegetables contain considerably higher amounts of calcium, compared with the calcium content in fruit. An 8-oz. serving of low-fat milk contains 300 mg of calcium, while a serving of low-fat yogurt has 400 mg of calcium, per USDA figures. An ounce of cheddar cheese contains 204 mg of calcium. Some types of fish are also high in calcium, including sardines, which have 242 mg per serving. Plant foods that are naturally rich in calcium include artichokes, providing 135 mg per medium-sized vegetable; boiled collards, which have 99 mg per 1/2-cup serving; and boiled turnip greens, providing 99 mg of calcium in every 1/2 cup. In addition to fruit juices, calcium is also added to certain foods, such as tofu and soy milk, which contain upwards of 130 mg and 150 mg per serving, respectively.
Calcium Citrate
You can also increase your calcium intake with nutritional supplements, including calcium citrate, made from citric acid. Calcium citrate is more expensive than another type of calcium supplement, calcium carbonate, and a 2001 study published in "Journal of the American College of Nutrition" concluded that both calcium citrate and calcium carbonate are equally effective in delivering absorbable calcium to the body. However, while calcium carbonate supplements may be more cost-efficient, calcium citrate is less likely to cause an upset stomach when taken without food.
Considerations
Although it would be hard to meet your daily calcium requirements from eating citrus fruits alone, citrus fruits are a good source of other important nutrients, including vitamins and antioxidants. Citrus fruits are also low in fat and contain fiber, which aids digestion. One medium-sized orange contains 69.7 mg of vitamin C -- almost a full day's worth -- as well as 237 mg of potassium, 39 mcg of folate, 3.1 g of fiber and 169 mcg of micronutrient antioxidants lutein and zeaxanthin. Grapefruit, both white and red varieties, is also a good citrus source of key vitamins and micronutrients, including vitamin A, beta carotene and antioxidant lycopene.
References
- National Institutes of Health Office of Dietary Supplements: Calcium
- USDA National Nutrient Database: Search
- Harvard University Health Services: Calcium Content of Common Foods in Common Portions
- "Journal of the American College of Nutrition"; Absorbability and Cost Effectiveness in Calcium Supplementation; Robert P. Heaney, MD; March 2001
- National Institutes of Health Office of Dietary Supplements: Vitamin C
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