December 5, 2005

8 Min Read
The News About Calcium


The News About Calcium

By Kimberlee J. Burrington
Contributing Editor

One of the most-studied minerals and the most commonly added to foods is calcium — the only mineral that has a health claim, too. Thanks to the National Dairy Council, Rosemont, IL, the U.S. population is well aware of the link between calcium consumption from dairy products and osteoporosis. Osteoporosis is a health benefits linked to calcium in the diet. Another benefit associated with calcium is good colon health. For those who aren’t good dairy consumers, ingredient companies have stepped up to provide a whole list of calcium ingredients.

Counting on carbonates

One of the most-common, economical forms of calcium is calcium carbonate. Forms include: naturally mined, or ground calcium carbonates (GCC), and naturally mined oyster shell calcium carbonates, or precipitated calcium carbonates (PCC). Naturally mined, or GCC, are natural, produced from the earth and acceptable for all-natural claims. Mined calcium is suitable for organic foods, but not all is created equal.

“The food and nutritional formulator needs to be aware of the differences in purity, consistency and versatility of the many products positioned for this market space,” says Tim Butler, senior manager marketing communications, Huber Engineered Materials, Atlanta. The considerable age of ancient oyster shells in the sea assures the purity and minimal contamination from live organisms of oyster-shell calcium carbonates. Precipitated calcium carbonate is synthesized by the conversion of calcium oxide to calcium hydroxide, then reacted with carbon dioxide to produce calcium carbonate. “All calcium-carbonate products contain approximately 40% elemental calcium by weight, making them a logical choice for food and nutritional formulators,” he says.

Solubility is important for calcium ingredients. Calcium carbonate is highly soluble at low pH, but has limited solubility at neutral pH. This is most apparent in beverage applications. A clear beverage at neutral pH, like fortified water, would be cloudy with the addition of calcium carbonate. In neutral beverages, like meal-replacement drinks, where clarity is not important, adding hydrocolloids to help suspend the calcium carbonate can offset the high density, and subsequent lack of solubility.

Most suppliers offer a variety of particle sizes to provide desired solubility and mouthfeel. “For most solid functional foods and nutritional supplements, the calcium-carbonate solubility is not a major issue, for once in the stomach — due to the low pH — it readily dissociates into a cationic form of calcium that readies it for absorption by the body,” says Butler. Beverages might be a challenging application for calcium carbonate, but it is used in significant volumes for breakfast cereal. Cereal producers often target the recommended daily allowance (RDA) in a single serving. Other products target lesser quantities.

Calcium carbonates’ absorption and bioavailability are similar, and have been compared to the bioavailability of milk calcium.

Enhanced calcium

Some nutritional studies have focused on enhancing calcium absorption through synergistic effects with other ingredients, like inulin. Dairy products, like yogurt with added inulin, have taken advantage of this work.

Some calcium ingredients come with more than just calcium. GTC Nutrition, Golden, CO, offers a prebiotic mineral blend that provides a variety of functional benefits: an ability to enhance flavors, mask off-notes, extend product shelf life and smooth textures. It offers prebiotic benefits in addition to calcium, magnesium and trace minerals, and meets optimal levels of calcium, as well as increases mineral absorption.

“This efficient combination of sea minerals and prebiotic fiber delivers an appropriate ratio of these functional ingredients to optimize and support healthy bone maintenance at a low cost,” says Juliana Zeiher, ingredient technologies manager, GTC Nutrition. The prebiotic portion is made up of shortchain fructooligosaccharides (scFOS™). A variety of studies show the scFOS in this mineral blend improves calcium absorption in animals and humans and promotes bone health. “Modulating the pH of the large intestine, which improves the solubility of calcium,” she continues, “extends the window of opportunity for calcium absorption.” ScFOS in this mineral blend “also increases the levels of calcium binding protein in the system, an active calcium carrier, assuring the highest mineral bioavailability,” she adds. A variety of studies show benefits of scFOS for bone and immune health and the company is currently conducting studies in the areas of joint health and reduction of arthritic pain.

This prebiotic mineral blend comes in two forms for different applications. One, suitable for RTD and powdered beverages “is composed of the carbonate form of minerals, and its enhanced bioactivity results from the combination of magnesium and trace minerals, which in addition to calcium, are crucial to healthy bone maintenance,” says Zeiher. It is also designed for neutral-pH beverages and has improved suspension when used with a hydrocolloid such as carageenan. The other form “contains calcium citrate and calcium malate for improved solubility in low-pH conditions, while delivering the benefits of 70 trace minerals,” she adds.

Typical use levels depend on the amount of minerals and absorption claims needed in the end product. Already utilized by the dairy and bakery category, this mineral blend is being more readily used in confections. “Consumers are constantly seeking ways of indulging without guilt, so better-for-you confections enhanced with calcium and other functional ingredients are convenient ways to reach consumers,” says Zeiher.

Lactates and gluconates

High solubility and dissolution rates make calcium lactate, calcium gluconate and calcium lactate gluconate some of the most-functional calcium ingredients. “A food-product developer would select one of our calcium sources if they were looking for a highly soluble calcium source with neutral taste, high bioavailability and quick-dissolution rate, which was easy to process,” says Sharon Rokosh, senior market development specialist, Purac America, Inc., Lincolnshire, IL.

Calcium contents range from 10% to 18% and solubilities range from 4 grams per 100 ml for calcium gluconate to 20 grams per 100 ml for calcium lactate gluconate. Dissolution time is an importantfactor in processing time; typical rates range from 25 to 45 seconds for 10% of calcium’s recommended daily intake in apple juice at 25°C, versus calcium citrate’s 600 seconds. Like other calcium ingredients, solubility increases as pH decreases. “We have calcium lactate and calcium lactate gluconates that have been optimized for solubility and for stability,” she adds. Designed for concentrates, premixes, carbonated soft drinks, syrups, low-temperature processing, mildflavored applications and in-line blending, these are optimized for stability and suited to applications that are more sensitive to calcium fortification, such as grape-juice-based beverages and iced tea.

Growing awareness of calcium’s health benefits and interest in bioavailability has led more people to actively look for calcium-fortified foods, even products that traditionally don’t use highly soluble calcium, like dairy and soy beverages, or mineral supplements, and cereals. These products also promote bonemineral density. In 2004 to 2005, the company commissioned a study by the Natural Marketing Institute (NMI), Harleysville, PA “to evaluate consumers’ attitudes, behavior and usage patterns of mineral-fortified beverages,” says Rokosh. “Feedback from this research indicated that 59% of consumers are interested in learning more about how calcium is absorbed in the body, and 53% indicated they would try a beverage with a more-bioavailable calcium source.” Adding calcium to low-pH beverages can also strengthen teeth and prevent dental erosion from acids. “In the NMI research, 68% of consumers were aware of the link between calcium and dental health,” she adds.

Milking mineral content

In addition to calcium, milk minerals supply other minerals required for good bone health. Comparing bone composition and milk-mineral composition shows identical calcium and phosphorus contents, 25% and 38%, respectively. Bone also contains magnesium, potassium, zinc, copper and protein, also found in milk minerals, but at somewhatlower levels than in bone.

“Bioavailability and absorption are not the same,” says Eric Bastian, director of R&D, Glanbia Nutritionals Inc., Twin Falls, ID. “Just because the calcium is absorbed doesn’t mean that it provides a physiological function, such as stronger bones. The bioavailability of a calcium ingredient should be based on its ability to generate denser, stronger bones.”

Bastian notes that calcium ingredients or milk have no differences in absorption, “but there are differences in bioavailability. You will absorb about 30% of the calcium, from milk or from most calcium ingredients. In diets fortified with 30% calcium from either a naturally derived dairy ingredient or calcium carbonate, rats fed the dairy ingredient showed more increases in bone density, bone strength and bonecalcium levels than a basal or calcium-carbonate diet.”

Glanbia’s natural mineral ingredient derived from milk that suspendable at neutral pH and soluble at acid pH. It is available in two different particle sizes, with the finer particle size enhancing suspension in neutral-pH beverages or used for better mouthfeel in frozen desserts. “We have some stabilizer systems that work well with products like a UHT milk or a yogurt smoothie to help suspend and stabilize the milk minerals,” says Bastian. With dairy products as a potential target of calcium fortification, there are some tricks to giving them even more calcium. For example, when making a yogurt with added fruit, milk minerals “can be added to the fruit prep to avoid concerns about the milk minerals settling- out of the yogurt during fermentation,” he adds. Look to add milk minerals in a variety of products, from dairy, juice and sports drinks to frozen desserts, confections, cereal and snacks.

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