May 9, 2010

Fortified Orange Juice Helps Body Gain Vitamin D

A new study suggests that fortified varieties of orange juice can help the body's vitamin D levels go up - just as effectively as the supplement itself.

This discovery could bring an addition to a very short list of sources for vitamin D, which is considered to be helpful in fending off an array of health problems like brittle bones, diabetes, and cancer.

"A lot of people don't drink milk," which has been fortified with vitamin D since the 1930s, "but they do drink OJ in the morning," the study's study author, Dr. Michael Holick, of the Boston University School of Medicine, told Reuters Health.

Just adding a vitamin to a food does not guarantee its absorption in the body.  There was a concern that only fatty foods like milk could be used because vitamin D dissolves in fat but not water. 

However, preliminary research a few years ago by Holick and his team suggests that orange juice might be an effective way to deliver the vitamin.  This prompted Minute Maid and Tropicana to begin adding it, as well as calcium, to some of their products.

The question still remains whether the body could make use of as much vitamin D from orange juice as it could from a supplement.  The team studied about 100 adults by having them drink a glass of orange juice every morning and to swallow a capsule each night for 11 weeks.

Some of the juices were fortified with 1,000 international units (IU) of vitamin D, while others were vitamin-free placebos that looked and tasted the same.  The capsules also came with or without vitamin D.  Participants were randomly assigned one of each.

The researchers reported in the American Journal of Clinical Nutrition that about 85 percent of the participants began the study with blood levels of vitamin D below the recommended healthy minimums.  Over the 11 week period, levels among those receiving vitamin D rose significantly.  The rise seems to be the same regardless of whether the vitamin was consumed in juice or in the form of a capsule.

Participants that received both the placebos showed no improvement in their vitamin D levels.

"The consumer now has one more option for obtaining vitamin D in the diet," Dennis Wagner, a PhD candidate at the University of Toronto, told Reuters Health by email. His research group recently added to the list themselves: cheese.

He said that unfortunately, government regulations currently only allow 100 IU of vitamin D to be added to a serving of food or drink.

Holick said he is concerned that even if the U.S. government revises its guidelines this summer, it will still be too low to ensure healthy levels of vitamin D through diet alone.  He recommends about 2,000 IU every day for adults and 1,000 IU every day for children.

Natural food sources are rare, and Holick believes it would be unrealistic to expect everyone to start taking supplements.

His solution is to have short spurts of unprotected time in the sun, the major natural source of vitamin D.  However, he does advice always protecting the face.

"Mother Nature designed the system very early to guarantee that we got enough vitamin D," Holick told Reuters. "Everyone was outside all the time, making it for free.'"

Wagner agrees, saying that humans could get a healthy dose of vitamin D in a relatively short period of time before the skin starts to turn red and the risk of skin cancers sets in.

"However, the reliance on sunlight exposure as the primary source of vitamin D is often impractical, especially in northern latitudes during the winter," added Wagner. "An increase in the number and variety of foods fortified with vitamin D will increase the availability of this important vitamin ... and prevent the detrimental health consequences associated with vitamin D deficiency."


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