If you live in North America, chances are good you don't get enough vitamin D. And when food companies want to focus on products that enhance bone health, incorporating vitamin D is a good way to do it. About 42 percent of Americans are deficient in vitamin D, according to the journal Nutrition Research. That's a big percentage, and also why vitamin D is being added to the updated Nutrition Facts Panel listing requirements.
A vitamin D deficiency can harm health in ways we may not expect. Symptoms of vitamin D deficiency include bone pain, muscle weakness, higher blood pressure and depression.
Innova Market Insights (www.innovadatabase.com) says the market for bone and joint health food products still remains very niche, as product launches it tracked with either a bone or joint health claim represent under 1 percent of all global food and beverage launches in 2014 and again in 2015.
With few natural food sources of vitamin D, processors can fortify foods with vitamin D to help consumers meet recommended daily intakes. Vitamin D supports calcium metabolism, and both of these nutrients are critical for bone health throughout life. Calcium is essential to bone remodeling (over time, bones can develop cracks), explains Robert Gagel, director of the Bone Disease program at the University of Texas and immediate past president of the National Osteoporosis Foundation (NOF).
In addition to its role in bone health, vitamin D helps with cognitive impairment, asthma, cancer and the risk of cardiovascular disease. As a hormone, vitamin D helps raise calcium in the bloodstream by increasing the body's ability to absorb calcium from foods and by reducing the amount of calcium lost in urine. As a last resort, it will boost calcium in the bloodstream by pulling calcium from the bone to support blood levels. And that's not always a good thing.
Greatest sources are fortified
While fish is a good source for vitamin D, fish consumption remains low in the U.S., making eggs and dairy foods favorable dietary alternatives to help increase vitamin D consumption, according to the American Egg Board (www.aeb.org). With that nutrient concentrated in the yolk, one large egg (50g) contributes 41 IU of vitamin D.
Certain mushroom species, including shiitakes, contain as much as 5 percent vitamin D, says the American Society of Nutrition in its Advances in Nutrition journal. "Mushrooms stand out in the produce aisle as a source of vitamin D and one of the few non-fortified food sources," notes the Mushroom Council (www.mushroominfo.com), Redwood Shores, Calif. In fact, the Institute of Medicine recognizes mushroom as the exception to the rule that plant foods don’t naturally contain vitamin D.
Yet the greatest food sources of vitamin D aren't whole, natural foods, but processed foods that are fortified, and food companies receive requests for fortification across a broad spectrum of products. Dairy-based, calcium-rich beverages such as milk are popular for strengthening bones, and like most foods, milk doesn't naturally contain vitamin D. Still, the majority of consumers consider vitamin and mineral content milk's most important attributes, Mintel (www.mintel.com) says. Bone health and taste are leading reasons why people drink dairy milk, the market research firm points out. However, Mintel also says dairy milk sales are still declining in favor of non-dairy milks, flavored, organic and lactose-free versions, which are seeing significant growth.
Providing milk-equivalent quantities of bioavailable calcium, Switzerland's Omya International AG (www.omya.com) offers Calcipur natural calcium carbonates (about 40 percent) for the fortification of vegan based on soy, rice, oat, coconut or almond drinks as well as products like snacks, breakfast cereals and baked goods. The concentrated powdered calcium works with various viscosities, says Tanja Budde, head of Omya's innovation and technical marketing. Budde says different particle sizes are available to ensure stability and a low sedimentation rate.
"The growing desire for vegan options is a current driver [for bioavailable calcium]," explains Stefan Lander, vice president consumer goods at Omya. "Many consumers now eschew cow milk products because of ethical or intolerance reasons, but don’t want to miss out on their nutritional benefits. We help develop non-dairy drinks that combine indulgence with a highly valuable nutritional profile."
Building bone density
Vitamin D supplementation is available in two types: vitamin D2, also called ergocalciferol, and vitamin D3, also known as cholecalciferol — both of which are good for bone health, the NOF says. Beverages like juice drinks are supplemented with calcium and vitamin D3, and soy-based beverages and soy products with vitamin D2.
Supplying most of the vitamin D in the diet, dairy products like yogurt and low-fat cheese are rich in bone-building calcium and are often fortified with vitamin D. It turns out that the vitamin isn't found in all yogurt. Even within a particular brand of yogurt, some products may have vitamin D while others don't.
Scientists previously looked at the connection between vitamin C and bone development, but were unsure whether or not it would help increase bone density. Now, researchers say the vitamin C in orange juice actually can boost bone density and produces collagen, a substance that forms the body's connective tissues. Fortified orange juice, such as Coca-Cola's Minute Maid Pure Squeeze orange juice with calcium and vitamin D, can have as much calcium as a glass of milk.
The Journal of Agriculture Food Chemistry reports that apples are a good source of polyphenols, which have been shown to increase the production of osteoblasts, the cells that secrete the matrix for bone formation and promote bone health. Polyphenols can also be found in flavone-rich orange juice. A 2005 study conducted in France showed that phloridzin, a polyphenol exclusively found in apples and especially concentrated in apple peels, can prevent bone loss.
Prunes are emerging as a surprising fruit that can have a positive impact on bone health. They contain a variety of nutrients that play a role in bone building, structure, maintenance and breakdown, says Stephanie Harralson, senior product manager at Sunsweet Growers (www.sunsweet.com), Yuba City, Calif. "Eating prunes supports bone health, especially in postmenopausal women. Prunes contain important vitamins and minerals like potassium, copper, boron, magnesium and vitamin K, which has shown to have bone protective effects." Additionally, she says prunes are filled with polyphenols.
"The connection between prunes and improved bone health I’ve seen in my research is fascinating, and continues to drive research interest in ongoing studies as we attempt to learn all we can about strengthening bones through nutrition," explains Shirin Hooshmand, assistant professor of nutrition at San Diego State University. "Adding a serving of prunes to your daily diet is an easy lifestyle change that may help to improve your bone health."
Combined with the appropriate treatment and physical activity, nutrition plays a more important role in optimizing bone health and reducing the risk of osteoporosis than first thought. Sunsweet's research also indicates that osteopenic, postmenopausal women who ate 50g of prunes a day (about 4-5 prunes) for six months experienced improved bone mineral density at the end of the clinical trial. This finding supports previous research with similar results from participants who ate 100g of prunes (10-12) a day.
Other skeleton-saving nutrients
Potassium and magnesium are nutrients not widely known to keep bones healthy, but they do. Potassium neutralizes acid in the body, and the acid can leach calcium out of bones. A baked, medium-size sweet potato with no salt has 31g of magnesium and 542mg of potassium. Five medium fresh figs also have about 90mg of calcium and potassium and magnesium. A half cup of dried figs has 120mg of calcium.
Dark leafy greens such as bok choy, kale, broccoli and spinach contain vitamin K, which is mostly known for helping out with blood clotting, but also helps the body make proteins for healthy bones. Other major sources of vitamin K are from eat, poultry, fish and grains.
Formulators might also consider adding almonds to a product recipe where appropriate. Richard Waycott, CEO of the Almond Board of California (www.almonds.com), Modesto, Calif., says almonds contribute a good amount of vitamin E, magnesium and manganese, and are a good source of fiber, copper, phosphorous and riboflavin. One cup of raw almonds has more calcium than a cup of milk – 378mg versus 300mg.
Raw almonds and almond products have certain benefits over cooked because many of the nutrient components, including enzymes, can be destroyed by heat, says Vivian Goldschmidt, founder of the Save Institute (saveourbones.com), a Boca Raton, Fla., organization dedicated to reversing and preventing diseases.
In December, a significant development was announced regarding the reversal of osteoporosis. Scientists at the Children's Medical Center Research Institute at the University of Texas Southwestern Medical Center, Dallas, uncovered a new bone-forming growth factor that may reverse bone loss associated with osteoporosis. They say the discovery of Osteolectin, or Clec11a, which is known to be made by certain bone marrow and bone cells, has implications for regenerative medicine. The UT researchers showed Osteolectin promotes the formation of new bone from skeletal stem cells in the bone marrow.