Posts Tagged ‘bioavailability’

Antioxidants: The Potency Debate

Tuesday, June 14th, 2011

 by Toni Tarver

Every day, consumers are inundated with messages extolling the benefits of antioxidants and their potential remarkable ability to clear harmful free radicals from the body. In fact, it is impossible to walk down the aisles of any supermarket without seeing a myriad of food products with labels announcing the level of antioxidants they contain. But many of those messages may be misleading as much of the information about the health benefits of antioxidants is exaggerated and, some say, downright deceptive.

In Session 253, “Antioxidants, Science, and Health: New Perspectives,” presenter John Finley of Louisiana State University discussed how the information about the properties and benefits of antioxidants has largely been exaggerated and misconstrued. He pointed out that processing profoundly affects the potency and bioavailability of antioxidants in various foods. Moreover, some antioxidants that show promise in laboratory studies have limited or no effectiveness within the human body, Finley said. Once antioxidants are ingested, many either lose their potency or are inadequately absorbed by cells. To illustrate his point, Finley referred to a recent study showing that anthocyanins from blueberries were helpful in protecting cells from inflammation but useless at treating cells that were already inflamed.

Presenter Navindra Seeram of the University of Rhode Island had a slightly different view of the efficacy of antioxidants within the body. Seeram and his colleagues believe that the body indeed absorbs antioxidants but that the mechanisms scientists use for detection and absorption are ineffective. He presented data indicating that after antioxidants are ingested, the body metabolizes them into other compounds that are either poorly studied or not documented at all in science. Presenter Darryl Sullivan of Covance Laboratories endorsed this perspective. Sullivan pointed out that more than 5,000 phytochemical compounds exist; most of them have not been identified. Research on antioxidants is in its infancy, he said, and scientists have a lot more to learn. In addition, he stressed that some of the current methods for studying and detecting antioxidants are good, but many more methods are needed.

Discussions on the processing of antioxidant-rich foods and the degree of antioxidant absorption in the body could soon be irrelevant. Presenter Li Li Ji of the University of Wisconsin presented compelling data on how exercise facilitates the body’s inherent ability to scavenge and get rid of free radicals. His research indicates that moderate exercise appears to have a deleterious effect on free radicals within the human body (rigorous exercise apparently has the opposite effect).

The debate on the healthfulness of antioxidants is sure to continue, but in the meantime, consumers should continue to eat fruits and vegetables (both rich in antioxidants) and engage in moderate physical activity just in case.

Effective Delivery of Bioactives in Functional Foods

Monday, June 13th, 2011

The first wave of nanotechnology applications in foods is focused on enhanced uptake and bioavailability of bioactives. The efficacy and absorption of bioactives delivered orally may be hampered by environmental degradation, enzyme attack, insolubility in transport fluids, and low residence time in the GI tract. Delivery vehicles in the form of emulsions, liposomes, solid lipid nanoparticles, and polymeric nanoparticles have been developed to increase bioavailability of various bioactives. Critical developments made in the area of nanodelivery applications for drug delivery can be translated and applied in food applications.

On Tuesday morning from 8:30–10:00 am in Room 283, Session 227 Designing Nanoscale Vehicles for Effective Delivery of Drugs and Bioactives in Functional Foods will cover topics ranging from information transfer between the drug and food industries, design of nano-delivery systems for food use, and improved efficacy and bioavailability of bioactive compounds via nano-sized delivery systems.

Presenter Edgar Acosta, Ph.D., Univ. of Toronto, will share his recent work on in-vitro uptake of self-emulsifying systems and the use of ternary phase diagrams to guide the formulation of self-emulsifying (nanoemulsions) for oral delivery of food bioactives.

Researcher Cristina M. Sabliov, Ph.D., La. State Univ., will focus on delivery of a model lipophilic vitamin, vitamin E, with anionic poly (lactic-co-glycolic) acid nanoparticles and with muco-adhesive cationic poly (lactic-co-glycolic) acid/chitosan nanoparticles. The data show that the developed nanodelivery systems resulted in an effective and controlled delivery of the vitamin to the small intestine, while increasing the passive intestinal uptake of vitamins, which ultimately results in improved vitamin bioavailability.