The Selenium Balancing Act

Selenium, a relative newcomer in the world of functional-food ingredients, is a trace mineral found naturally in soil. While it holds a firm position in the supplement arena, it is gaining recognition in the food industry as research in support of its health benefits mounts.

Dietary sources of selenium include organ meats, seafood, and unrefined grains and nuts, particularly Brazil nuts. In the United States, average adult daily intake of selenium ranges from 80 to 110 mcg per day. The recommended daily dietary allowance for selenium is 55 mcg for adults.

Health matters

“Emerging scientific evidence suggests a strong relationship between selenium intake and the prevention of certain types of cancer,” says Lakshmi Prakash, Ph.D., vice president of innovation and business development, Sabinsa Corporation, Piscataway, NJ. “Large-scale studies are still underway, and will provide detailed insight when completed in 2012. These studies target determining the efficacy of vitamin E and selenium in preventing prostate cancer and dementia/Alzhiemer’s disease, respectively. Meanwhile, smaller clinical studies continue to validate the health benefits of selenium in cancer prevention.”

Other preliminary studies suggest the beneficial role of selenium in delaying the progression of arthritis; inhibiting oxidation of low-density lipoprotein cholesterol; mimicking the action of insulin; reducing the severity of epileptic seizures in children; improving mental fatigue and anxiety in adults; improving skeletal muscle strength in the elderly; and strengthening the immune system.

Interestingly, “selenium supplementation in individuals who are not overtly selenium deficient appears to stimulate the immune response,” according to the Linus Pauling Institute, Oregon State University, Corvallis.

But there’s a catch. Too much selenium in the diet can lead to selenosis, a condition marked by gastrointestinal upsets, hair loss, white blotchy nails, garlic breath, fatigue, irritability and mild nerve damage. To prevent the risk of this condition, The Institute of Medicine of the National Academy of Sciences, Washington, D.C., has set a tolerable upper intake level for selenium at 400 mcg per day for adults.

Form equals function

In functional-food formulation, not all selenium is created equal. “Inorganic forms, such as sodium selenite, are not compatible with food formulations,” Prakash says. “L-selenomethionine, the natural form of selenium present in cereals, other plant foods and high-selenium yeast, is a bioavailable form compatible with foods. Additionally, it can be dissolved in hot water, or dry blended with food formulations.”

Rocky road

From a regulatory standpoint, this new kid on the functional food block is currently suffering some growing pains. In 2003, FDA allowed a qualified health claim for selenium and cancers. This year, citing a 2006 report from Agency for Healthcare Research and Quality, Rockville, MD, FDA is questioning if new science supports the claim, and if the language “should be modified to reflect a stronger or weaker relationship.”