October 23, 2007

(SACRAMENTO, Calif.) — Men and women who are 60 and older, nonsmokers and in good health are needed for a UC Davis  study on the effects of cranberry juice on senior citizens' responses to the influenza vaccine.

The study aims to determine if cranberries can counteract the normal deterioration of the immune system as the body ages. Known as immunosenescence, the aging process results in a diminished response to the flu vaccine in senior citizens. Although the vaccination is effective in reducing the severity of influenza in people 60 and older, the response is less than that of younger people.

Influenza is a major health problem among elderly people in industrialized countries. An estimated 90 percent of the 10,000-to-40,000 deaths attributed to the disease annually in the United States occurs in people 60 years and older, and death rates increase significantly in those 85 and older.

Immunosenescence begins approximately between the ages of 55 and 60, and its effect on the immune system is manifested in a relative inability of senior citizens to produce a protective response following vaccines. Stress from oxidation, a chemical reaction in molecules that damages cells, is a common mechanism that impairs immune function and also has been implicated in immunosenescence. Substances known as antioxidants protect cells from the unstable molecules produced by oxidation, known as free radicals. Antioxidants are found in fruits and vegetables.

Nutritional approaches have been proposed to counteract the damaging effects of aging on the immune system, and previous research involving vitamin E supplementation has produced promising results.

The UC Davis study, to be conducted by researchers from the Department of Internal Medicine and the Department of Food Science and Technology, will assess whether a specific nutritional component of cranberry juice will boost the effectiveness of the immune system in older individuals. Because cranberries have the highest content per serving of polyphenols, a group of chemicals in plants that act as antioxidants, the UC Davis researchers believe that it is the best candidate to counteract immunosenescence.

Subjects in the study will be randomly selected to receive either a daily amount of cranberry juice or a non-fruit-based drink of similar flavor. After four weeks, all subjects will receive the flu vaccine, free of charge. The researchers will evaluate the immunological response to the vaccination in each group. The study will last eight weeks. Compensation will be paid to all volunteers who complete the study.

The principal investigator of the study is Carlo Selmi, assistant professor of medicine in the Division of Rheumatology, Allergy and Clinical Immunology.

For more information and to enroll in the study, call (530) 752-2884 or cfselmi@ucdavis.edu.