B Vitamins May Reduce Cervical Cancer Risk


Healthnotes Newswire (February 26, 2004)—Women with low dietary intakes of vitamins B1 (thiamine), B2 (riboflavin), B12 (cobalamin), and folic acid may be more at risk of developing premalignant changes in the cervix (called cervical dysplasia), according to a new study in Cancer Causes and Control (2003;14:859–70). The findings suggest that increasing the intake of these vitamins may help prevent the development of cervical cancer.

Although cervical cancer only comprises 1.5% of all cancers in women and the incidence has steadily declined by approximately 2% per year since 1955, it can be fatal if it is not detected in time. The decrease in cervical cancer has primarily been attributed to the the Pap smear now used to detect early abnormal changes in the cells of the cervix. Risk factors for cervical cancer include smoking, oral contraceptive use, a diet low in fruits and vegetables, and a family history of cervical cancer. Infection with human papilloma virus (HPV; a sexually transmitted virus that causes genital warts and is associated with causing cervical dysplasia), or other sexually transmitted diseases such as chlamydia, also increases a woman’s risk of developing cervical cancer. Increasing the intake of B vitamins may help prevent women from having to undergo surgery to treat either cervical dysplasia or cancer.

In the new study, 214 women aged 18 years and older with low- or high-grade cervical dysplasia and 270 healthy women completed questionnaires regarding their typical daily diet. (The grade of dysplasia represents the degree to which the cells of the cervix have abnormally changed. High-grade dysplasia suggests the cells are closer to becoming cervical cancer, while low-grade dysplasia indicates that the cervical cells have undergone abnormal changes, but not to the same extent as seen with high-grade dysplasia.) The frequency and quantity of all foods, alcohol, and nutritional supplements consumed were recorded. Specific nutrient levels were calculated based on intake from food alone, supplements alone, and food and supplements combined. Each woman was also tested for HPV infection.

More than 70% of the women diagnosed with cervical dysplasia were infected with HPV, compared with 10% without cervical dysplasia. HPV infection was more associated with high-grade cervical dysplasia than low-grade cervical dysplasia. Higher intake of vitamins B1 and B2 from food sources, vitamin B12 from supplements, and total folic acid (from food and supplements) was associated with a decreased risk of developing high-grade cervical dysplasia. Low-grade cervical dysplasia risk decreased as intake of vitamin B2 from food and total folic acid increased. The risk dropped by 50 to 90% for the highest intake of these nutrients, compared with the lowest intake. A significant increase in high-grade cervical dysplasia was observed in smokers or alcohol drinkers (even in small quantities) with low levels of B vitamins, compared with nonsmokers and nondrinkers with high intakes of these nutrients.

The authors of the current study suggest that HPV infection may be associated with low nutrient intake of B vitamins and that women who are relatively depleted of these vitamins may be more susceptible to cervical dysplasia. Studies have shown that oral contraceptive pills deplete the body of B vitamins and their use is known to increase the risk of cervical dysplasia, adding support to this theory. However, studies have yet to clearly show that this is true. Nonetheless, B vitamins are relatively safe and inexpensive and may add to the arsenal of nutrients to prevent cancer.