Vitamin D is as important as calcium for the maintenance of a healthy body and a solid skeleton to hang it on. Vitamin D aids the absorption of calcium, and regulates how much of the mineral we need. There is no recommended dietary allowance for vitamin D. However, government health experts set adequate intake levels of 10-12 mcg per day (based on an assumption of no vitamin D through sunlight, a major precipitator of the nutrient).
Calcium - and its careful equilibrium - plays a crucial role in many functions. For example, calcium is necessary for blood vessel constriction and relaxation, blood clotting, nerve function, and hormone secretion (for example, insulin). These functions are so vital, the body will demineralize bone to maintain its optimum, yet narrow, range of concentration.
When blood calcium decreases, vitamin D is converted to its active form, vitamin D3 (calcitriol). Calcitriol increases calcium absorption and decreases its excretion. It can also stimulate bone breakdown to release calcium. When blood calcium rises, the system reverses. This tight control of blood calcium is not only at the expense of the skeleton, but under the guidance of vitamin D.
Few foods - fish oil and egg yolks - are naturally rich in vitamin D, but the most common source is nondietary: Sunlight naturally converts a derivative of cholesterol to vitamin D.
D is for Deficit
Today, continued underexposure to the sun could be driving a vitamin D deficiency in many people. In fact, some health experts have described D deficiency as a resurging epidemic, with the elderly, pregnant women, and teenage girls most at risk. This could have far-reaching consequences because vitamin D, like calcium, is tied into many vital functions.
Receptors for vitamin D are present in many different organs in the body, including the small intestine, colon, bones, immune cells, the pancreas (responsible for making insulin), brain, heart, skin, gonads, prostate and breast. In other words, vitamin D's "got connections," and a deficiency can wreak physical havoc.
A recent analysis of studies on vitamin D and cardiovascular disease in patients with chronic kidney disease concluded vitamin D may reduce the inflammation of atherosclerosis, help reduce heart muscle enlargement (which leads to congestive heart disease), and lower hypertension.
Strategies of Supplementation
"The biggest category for [calcium and vitamin D] fortification is in beverages," says Melanie Snyder, marketing manager for consumer products at Specialty Minerals Inc. (www.mineralstech.com), Bethlehem, Pa. "These beverages include water, soy milk and energy drinks. Soy beverages are the biggest growth area right now."
|Imagine Foods' Rice Dream Heartwise non-dairy beverage is enriched with vitamins A, D and B12 and has the same calcium as dairy milk.
Cereals, nutrition bars, soy milk and similar products are often fortified with highly bioavailable calcium carbonate. "We find that our GCC [ground calcium carbonate] products are well suited to baked goods, such as nutritional bars and baking mixes," says Snyder.
Specialty Minerals also provides a line of precipitated calcium carbonate products in different particle shapes and sizes to suit specific applications. "We offer a 0.7-micron product called Vicality Albafil PCC which works extremely well in fortified beverages, such as soy milk," explains Snyder. "The product displays very good suspension properties and because of the small particle size, it provides no 'off' taste, chalkiness or negative mouthfeel as a ground calcium carbonate would."
Vitamin D is fat-soluble and its use in fortification presents a different set of challenges than calcium. DSM Nutritional Products, Parsippany, N.J., makes vitamin D3 available in crystalline form, as well as in an oil-based solution to suit a variety of applications. Since vitamin D is also sensitive to oxidization, another method for increasing stabilization in formulations is through microencapsulation, as with Fairfield, N.J.-based LycoRed's CapsuDar vitamin D.
When Dairy Isn't an Option
Pacific Natural Foods Inc., Tualatin, Ore., supplies a wide variety of dairy replacement beverages made from soy, as well as from oats, rice, hazelnuts and almonds. All are organic, low-calorie and fortified with calcium, vitamin D and other vitamins found in dairy milk.
Imagine Foods Inc., Boulder, Colo., provides an extensive line of enriched soy and rice beverages with calcium and vitamin D levels similar to dairy products. "The trend to fortify foods and beverages with calcium will continue," says Tim Butler, senior marketing communications manager for Huber Engineered Materials (www.hubermaterials.com), Atlanta, providers of calcium carbonate. Other forms of calcium used in fortification include calcium citrate, calcium gluconate and calcium lactate.
"One of the key determinants of what will be fortified is the mouth-feel and solubility of the calcium in the formulation of the product. Formulators also seek to optimize the dissolution of the calcium in the mouth and gastrointestinal tract. Purity is paramount in ingredient formulation," continues Butler. "The higher the purity, the less likely the impurities will interact with other ingredients."
Meeting one's calcium needs may be as simple as drinking water. Naturally occurring calcium in mineral water is as readily absorbed as that from dairy products, and since calcium-rich mineral water has no calories it's an easy way to increase the calcium density of the entire diet.
Nestlé Waters, Stanwood, Mich., offers Contrex, a bottled water from a source rich in natural calcium and magnesium. Whitestone, N.Y.-based Glacéau's (www.glaceau.com) multi-v flavored water is a lightly sweetened vitamin-enriched water with calcium lactate and calcium carbonate. "Glacéau provides responsible hydration options that are natural and free of sodium, artificial sweeteners, chemical preservatives and other ingredients that are hard to pronounce," says Jessica Wolff, communications manager for Glacéau.
Another strategy for obtaining calcium is to increase its absorption. Inulin, a fructose polymer used as a fiber supplement and prebiotic, may enhance dietary calcium absorption and potentially improve bone density. "Consumer awareness of the importance of bone health has led to the growing popularity of calcium-fortified products," said Steve Snyder, vice president of Cargill Health & Food Technologies (www.cargillhft.com), Minneapolis. "Science supports the incorporation of inulin into calcium-enriched foods with mass-market appeal because (the oligofiber) may boost calcium absorption in critical times, such as during post-menopausal and pre-teen years."
Another inulin product, from Orafti Active Food Ingredients (www.orafti.com), Malvern, Pa., has been clinically proven to improve bone health. "Our enriched blend of inulin, Raftilose Synergy 1, when consumed along with calcium helps to boost the body's absorption of calcium by as much as 20 percent," says Hilary Hursh, Orafti food and nutrition scientist.
Nearly 10 million Americans suffering from osteoporosis. Twice that number have decreased bone mass. The total national health cost for these conditions is almost $15 billion a year. With figures like that, the importance of calcium and vitamin D fortification cannot be overestimated.
Calcium and Obesity
Some studies suggest calcium lowers body fat. It must be noted with regard to most of these studies that dairy calcium may be more effective than supplemental calcium. Possibly there are other substances in dairy products, such as whey protein, or conjugated linoleic acid that contribute to fat loss. Much more research is needed before the relationship between dietary calcium and body fat is clear.