Even though humans have the ability to make vitamin D when ultraviolet rays of the sun meet the skin, many Americans fail to get enough vitamin D.

Even though humans have the ability to make vitamin D when ultraviolet rays of the sun meet the skin, many Americans fail to get enough vitamin D. In fact, vitamin D deficiency in this country is being called a silent epidemic. The prudent use of sunscreen, sun-blocking pollution and long, cold winters indoors are partially to blame.

Milk is the leading source of vitamin D in the American diet. The recommended three 8-ounce glasses of low-fat or fat-free milk provides 75% of the Daily Value for vitamin D.

Vitamin D was originally added to milk in the 1930s to prevent infantile rickets, which is a softening of bones in children that can lead to fractures and deformity. This practice virtually eradicated the disease in the United States.

Indeed, bone building is vitamin D’s original claim to fame, but new and emerging research suggests vitamin D may be far more versatile, offering an array of health benefits. Some preliminary research suggests vitamin D may support a healthy immune system, heart health, normal blood pressure and healthy aging. And, ongoing research continues to explore the potential connection between vitamin D and certain diseases, including some cancers.

Despite the newfound fame for vitamin D, Americans of all ages still appear to be coming up short. For example, some researchers estimate that up to 55% of adolescents may be deficient, putting them at increased risk for osteoporosis and debilitating bone diseases, according to one recent analysis of children living in the northeastern United States. The researchers believe the trend of soft drinks replacing milk may be one important reason for this trend. The problem could be even worse as Americans get older. According to recent government data, only 4% of men and 1% of women over the age of 51 meet vitamin D recommendations from food. The researchers found that even some infants and small children seem to be failing to get enough vitamin D. Experts suggest the chronic low intakes of vitamin D have been behind the resurgence of rickets.

Federal Standards of Identity for milk and flavored milk state that vitamin D fortification of milk is optional. However, due to the importance of vitamin D’s role in conjunction with other nutrients in milk that help build strong bones, milk processors are strongly encouraged to fortify all fluid milks with vitamin D.

According to federal regulations, all fortified milk sold in the United States should contain 400 International Units (IU) of vitamin D per quart. But why stop with milk? The food additive provisions for direct addition of vitamin D permit its use in other milk-based products including cultured dairy foods, cheese and cheese products, as well as calcium-fortified fruit juice, soy beverages, infant formula, margarine, meal replacement bars, breakfast cereals, pasta and grain products. However, at this time vitamin D is not permitted to be added to ice cream, sherbet, water ice or frozen desserts.

Indeed, why stop with milk…especially since research shows that the calcium naturally present in cows milk and products made from cows milk, is better for bones than calcium derived from other sources and used to fortify some foods and be made into supplements.

Industry-funded research published in the August 2009 edition of theJournal of Bone and Mineral Researchsuggests that calcium from dairy products can help ensure stronger bones than calcium derived from fortified, non-milk based goods. Researchers from Purdue University said that, over 10 weeks, rats fed a diet of nonfat dry milk products had denser, stronger and longer bones than rats given supplements such as calcium carbonate. Researchers did not identify the cause for the recorded improvements of dairy calcium to any specific factor and suggested further research may be needed in identifying where potential benefits may be coming from. Professor Connie Weaver, head of Purdue University’s food and nutrition department, and one of the study’s authors, says that this study was the first of its kind to directly compare calcium properties derived from supplements and milk.

Dairy processors have the best base material out there for vitamin D fortification. Make a resolution to add the sunshine vitamin to more of your dairy foods in 2010.