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Link suggested between maternal diet and childhood leukemia risk

| 26 August 2004

A growing number of scientists believe that genetic changes linked to cancer later in life begin in the womb. Prior studies on children diagnosed with leukemia — the most common childhood cancer in the United States — have found that blood samples taken at birth tested positive for the same genetic markers that were later found in the cancer.

Now, a new study led by Berkeley researchers suggests that women who eat diets rich in vegetables, fruit, and foods containing protein before pregnancy may have a lower risk of giving birth to a child who develops leukemia. The study, published in the August 2004 issue of Cancer Causes and Control, marks the first time researchers have conducted a systematic survey of a woman’s diet and linked it to childhood leukemia risk.

“It goes back to the old saying to expectant mothers, ‘You’re eating for two,’” says study co-author Patricia Buffler, professor of epidemiology and head of the Northern California Childhood Leukemia Study, a federally funded study on the link between environmental exposures and leukemia. “We’re starting to see the importance of the prenatal environment, since the events that may lead to leukemia are possibly initiated in utero. Leukemia is a very complex disease with multiple risk factors. What these findings show is that the nutritional environment in utero could be one of those factors.”

The researchers compared 138 women, each of whom had a child diagnosed with acute lymphoblastic leukemia (ALL), with a control group of 138 women whose children did not have cancer. After comparing the women’s diets in the 12 months prior to pregnancy, the researchers found that the higher the intake of vegetables, fruit, and foods in the protein group, the lower the risk of having a child with leukemia.

“Fetal exposure to nutritional factors has a lot to do with what mom eats,” said Christopher Jensen, a nutritional epidemiologist and lead author of the paper. “These findings show how vital it is that women hoping to get pregnant, as well as expectant moms, understand that critical nutrients in vegetables, fruit, and foods containing protein — such as meat, fish, beans, and nuts — may protect the health of their unborn children.”

The few studies that have been conducted on maternal diet and childhood cancer risk looked only at specific foods or supplements, and results have been mixed. This study is the first attempt to capture a woman’s overall dietary pattern — using a 76-food-item questionnaire — and its relationship to the development of leukemia in a child.

No new liver lovers

Although the researchers surveyed only the foods eaten in the year before conception, they point to studies showing that dietary patterns remain stable throughout pregnancy.

“The general habits of what you like and don’t like to eat are not likely to change during pregnancy,” said the study’s principal investigator and co-author, Gladys Block, professor of epidemiology and public health nutrition. “If you hated liver before you got pregnant, you’ll probably hate liver while you’re pregnant.”

Within the fruit and vegetable food groups, certain foods — including carrots, string beans, and cantaloupe — stood out as having stronger links to lower childhood leukemia risk. The researchers point to the benefits of certain nutrients in those foods (e.g., carotenoids) as potential protective factors.

“This finding is consistent with research about the benefits of a diet high in fruits and vegetables in preventing adult cancers,” said Block. “The positive message here is that mothers may be able to transfer some of those benefits to their children.”

One of the more surprising results of the study is the emergence of protein sources, such as beef and beans, as a beneficial food group in lowering childhood leukemia risk. The researchers looked further and found that glutathione was the nutrient in the protein group with a strong link to lower cancer risk. An antioxidant found in both meat and legumes, glutathione plays a role in the synthesis and repair of DNA as well as in the detoxification of certain harmful compounds.