A diet low in a B vitamin called folic acid or folate makes a woman more susceptible to cervical cancer caused by human papilloma virus, researchers from the University of Alabama Medical School reported last week in the Journal of the American Medical Assn. The human papilloma virus causes genital warts in both men and women.

The researchers found in a study of 464 women that those who had low levels of folate in their blood and were exposed to the virus were five times as likely to develop precancerous changes in their cervix as exposed women who had normal levels of folate. The precancerous changes are those normally detected by a Pap smear.

The researchers said the vitamin deficiency is most often caused by a diet lacking sufficient amounts of vegetables, fruit and, especially, orange juice. "The folate deficiency may explain why (cervical) cancer is so common among poor women," said nutritionist Charles E. Butterworth. Cervical cancer affects about 13,000 women per year, killing 5,000.