Elemental Calcium Facts

 This silvery-white alkaline-earth element forms more than 3% of the earth’s crust. It has an atomic mass of 40.078 and a density of 1.55 g/cm3. Chemists might recognize this description of calcium, but it doesn’t give much insight into its importance in nutrition or explain the options for incorporating it into foods.

The good stuffCalcium makes up about 1.5% to 2.0% of the human body, with about 98% in the bones, 1% in the teeth, and the rest in tissues and the circulatory system. It has become a popular fortification nutrient in foods and beverages — in everything from cereal and orange juice to soup and bread — because of its role in preventing osteoporosis, a disease that results in bone-mass loss that makes bones susceptible to fractures. We require it throughout life: first to build bones, then to maximize bone density, to maintain adult bone mass and, later in life, to minimize bone loss and prevent osteoporosis’s debilitating effects.

Calcium also plays an important part in the blood, nerves and muscles, particularly by regulating heart and muscle contraction, and nerve conduction. One study (“Calcium Supplements for the Prevention of Colorectal Adenomas,” J.A. Baron and others, The Calcium Polyp Prevention Study Group, New England Journal of Medicine, 1999) linked calcium supplementation “with a significant — though moderate — reduction in the risk of recurrent colorectal adenomas.” Other researchers propose deficient calcium affects premenstrual syndrome (“Micronutrients and the Premenstrual Syndrome: The Case for Calcium,” Susan Thys-Jacobs, Journal of the American College of Nutrition, 2000). And the Journal of the American College of Nutrition in 2002 (“Calcium and Weight: Clinical Studies” (Dr. Robert P. Heaney and others) reviewed several studies that linked lower calcium intake with weight gain, saying that the “data suggest that increasing calcium intake by the equivalent of two dairy servings per day could reduce the risk of overweight substantially, perhaps by as much as 70%.”

How much?The National Academy of Sciences, Washington, D.C., recommends that children ages 4 to 8 should consume 800 mg calcium/day, preteens and teens ages 9 to 18 need 1,300 mg, adults 19 to 50 need 1,000 mg, and those 51 and older require 1,200 mg. Calcium can be obtained from dairy products and other naturally calcium-rich foods in sufficient quantities to meet these daily requirements, but that just isn’t happening, hence the rising importance of calcium-fortified products.

According to the National Osteoporosis Foundation (NOF), Washington, D.C., in 2002, more than 10 million people suffered from osteoporosis; this figure might climb to 12 million by 2010 if the trend continues. It’s estimated that about 75% of the U.S. population currently has calcium-deficient diets.

Opportunity knocksAs the awareness and incidence of osteoporosis continues to grow, so does the need for calcium-fortified products. Ideally, most nutritionists recommend foods, especially lowfat dairy products, as the best source of calcium. Milk, yogurt and cheese provide about 25% to 30% of the RDA per serving (approximately 250 to 350 mg calcium/8 oz. of milk). However, the National Dairy Council, Rosemont, IL, notes: “Low intake of dairy foods ... is largely responsible for Americans’ low calcium intake. Americans are consuming an average of only 1.5 servings of dairy foods a day, or half the number of servings recommended in the Food Guide Pyramid.” So unless eating patterns drastically change, calcium fortification is here to stay.

To pique consumer interest, manufacturers can flag fortified products. FDA allows label claims for foods containing significant calcium levels: 10% or more of the Daily Value (DV) can use terms such as “calcium-fortified,” 10% to 19% DV may include “good source of calcium” and 20% DV may carry claims such as “high in calcium” or “excellent source of calcium.”

Additional directionsCalcium ingredients range from a variety of GRAS salts with various calcium contents — such as carbonate (40% Ca), chloride (27%), citrate (21%), gluconate (14%), lactate (14%) and phosphates (mono-, di- and tribasic with 17% to 38%); to dairy calcium (including high-calcium milk protein, and milk minerals), with calcium contents from 2% to approximately 25%; to new forms, such as a calcium amino acid, malic acid chelate complex, and calcium fumarate (19%).

Choosing the best calcium form for food fortification depends on a number of technical considerations, such as bioavailability, solubility, taste, palatability, stability and effects on the final product, as well as cost and consumer preference.

Nutrition experts estimate that we absorb only 25% to 35% of calcium consumed. Though there’s some disagreement, conventional wisdom — and most studies — say that dairy calcium, calcium citrate and calcium citrate malate are absorbed best in food products. Generally, organic salts (citrate, gluconate and lactate) have better bioavailability than inorganic calcium salts (phosphate and carbonate). But many factors influence the actual calcium absorbed by an individual, including other items in the diet and the calcium level consumed, intestinal conditions, calcium status, and age. Vitamin D and magnesium enhance absorption.

Inorganic salts tend to be less expensive. At high levels, they have a higher likelihood of imparting a chalky mouthfeel. Gluconate, lactate, fumarate and tricalcium phosphate are tasteless, although tricalcium phosphate can be gritty. Calcium citrate can come across as acidic and bitter, while calcium carbonate produces a soapy or lemony taste.Beverages typically need a relatively soluble ingredient. Calcium lactate has high solubility, 9.3 grams/liter, versus calcium fumarate’s solubility of 1.22 grams/liter and calcium citrate’s solubility of 0.2 grams/liter. A lower pH generally enhances solubility, as does a higher temperature.

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