Lydia Begola Van Zandt, 79, a former lecturer and writer on international affairs and a Washington resident for 43 years, died April 6 at Cottage Hospital in Santa Barbara, Calif., of inflammation of the pancreas.

A world traveler, Mrs. Van Zandt had visited 50 countries, interviewing government leaders and world figures. She was well known here and in New York City as a lecturer and book reviewer and her articles, monographs and reviews appeared in leading newspapers in this country.

Born in Denver, she attended the University of Chicago, where she studied theater arts and public speaking, and the Chicago School of Dramatic art. In the 1920s, she appeared in summer stock in the Chicago area and came to Washington as the understudy of Helen Hayes in a play at the National Theater. She had two seasons on the stage in New York City and appeared with leading actors such as Spencer Tracy.

After her marriage to Arthur E. Van Hagen in New York City, she left the theater to study politiccal science and journalism at Columbia University.

In 1933, they moved to Washington, and she began reviewing books for newspapers as a hobby. When her husband died in 1935, her hobby grew into a profession.

During a fact-finding world tour in 1936, she met and married Dr. J. Parker Van Zandt, in Manila. Dr. Van Zandt, a World War I pilot and aviation authority, is a former director of aviaton research for the Brookings Institution here and a former executive of Pan American Airways.

Mrs. Van Zandt was a charter member of the speakers research committee for the United Nations and attended the first United Nations Assembly in London in 1946 as an observer for the national board of the Young Women's Christian Association.

During World War II, she was a speaker for the American Red Cross and served as chairman of the D.C. Red Cross Radio Committee. She was a former chairman of the D.C. World Fellowship Committee of the YMCA and a member of the executive council and a former president of the society of Woman Geographers.

She lectured weekly on current events to wives of congressmen and cabinet officers for several years.

Mrs. Van Zandt's other memberships included the American Newskpaper Women's Club of Washington, the Chevy Chase Club, the Army and Navy Club in Washington andd the National Press Club.

She and her husband, who survives, retired to Montecito, Calif., in 1976.