Extra Fruits and Veggies May Not Protect Cancer Survivors
While
a healthy diet remains a mainstay of cancer prevention,
eating more than the recommended amounts of fruits,
vegetables, and fiber will not give you added protection
against breast cancer recurrence, says a study in the Journal
of the American Medical Association (JAMA).
This study of breast cancer survivors and cancer recurrence found no meaningful benefit for women who followed a diet that encouraged eating at least eight servings of vegetables and fruits, at least 30 grams of fiber, and no more than 15 percent to 20 percent of fat.
"These were healthy breast cancer survivors who were already eating at least five servings of fruits and vegetables,” says
study author John Pierce, Ph.D., at the University
of California, San Diego.
Dr.
Pierce and his team wanted to know “what happened when you really ramped that up. Some women ate 12 or more servings of fruits and vegetables a day," he
says.
"Clearly, there's a threshold for prevention,” explains Dr. Pierce. “You
don't have to go overboard. The national guidelines
are good enough."
October is National Breast Cancer Awareness Month. Breast cancer accounts for about one in three of all cancers diagnosed in women, according to the American Cancer Society.
More than 200,000 women are diagnosed with breast cancer in the US each year. More than 40,000 American women die from breast cancer annually.
Many previous studies have suggested that a diet full of fruits, vegetables, and fiber, but low in fat, can reduce the risk of certain cancers.
To assess whether or not improving the diet over and above what is already recommended could provide a more significant benefit, Dr. Pierce recruited more than 3,000 women who had already been diagnosed with and treated for early-stage breast cancer.
The women were between the ages of 18 and 70 and had no evidence of recurrent breast cancer at the start of the study.
The volunteers were randomly assigned to one of two groups.
The intervention group included 1,537 women who were given telephone counseling along with cooking classes and newsletters that recommended five servings of vegetables, one serving of vegetable juice, three servings of fruit, at least 30 grams of fiber, and no more than 15 percent to 20 percent of daily calories from fat.
A comparison group included 1,551 women who were given printed materials that recommended the current national guidelines of five servings of fruits and vegetables a day.
Throughout the study, the women were periodically asked to recall their diet in the past 24 hours. The researchers also checked for changes in certain substances in the blood that indicate fruit and vegetable intake. The average follow-up time was 7.3 years.
After four years, the researchers found that vegetable intake had increased in the intervention group by 65 percent, while fruit consumption was up by 25 percent.
Fiber intake was also increased, by as much as 30 percent, and fat intake was down 13 percent.
Even with this healthy diet during the study, there were no significant differences in the rates of breast cancer recurrence.
During the study period, 16.7 percent of women in the intervention group versus 16.9 percent of women in the comparison group received a diagnosis of invasive breast cancer.
There were also no statistically significant differences in mortality. In the intervention group, 10.1 percent of the women died compared to 10.3 percent in the comparison group.
Does that mean eating well will not help prevent cancer from returning?
"For women with breast cancer, the answer is out on whether or not there's a single constituent in the diet that will help,” says
Susan Gapstur, Ph.D., at Northwestern University, who
wrote an editorial in the journal.
“But, for overall health, maintaining a healthy weight and eating a healthy diet is always good," she
notes.
Dr. Gapstur points out that the women in the study were not able to meet the suggested reduction in fat intake.
Additionally, she says that there appeared to be some discrepancy in the number of calories consumed. By the end of the study, the average number of reported calories consumed in the intervention group was 180 less per day.
Dr. Gapstur says that such a change would have resulted in weight loss instead of the slight increase that the women experienced.
Rather than just one aspect of diet or lifestyle, Dr. Gapstur says she believes the next question researchers have to answer is all of these factors as a whole.
"We have to address the full spectrum - diet, physical activity, and obesity," she
says.
In
the meantime, she notes, "At the end of the day, it's
never wrong or bad to eat healthfully."
Dr. Pierce adds that exercise patterns are also important and suggested that women exercise moderately for about 30 minutes a day.
Always consult your physician for more information.
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Experts recommend improving eating habits and increasing physical activity to support an overall healthy lifestyle.
Eat five to nine servings of fruits and vegetables daily.
A vegetable serving is one cup of raw vegetables or one-half cup of cooked vegetables or vegetable juice.
A fruit serving is one piece of small to medium fresh fruit, one-half cup of canned or fresh fruit or fruit juice, or one-fourth cup of dried fruit.
Choose whole grain foods such as brown rice and whole wheat bread.
Avoid highly processed foods made with refined white sugar, flour, and saturated fat.
Weigh and measure food in order to be able to gain an understanding of portion sizes.
For example, a 3-ounce serving of meat is the size of a deck of cards. Avoid supersized menu items.
Balance
the food “checkbook.” Taking in more calories
than are expended for energy will result in weight
gain. Regularly monitor weight.
Avoid
foods that are high in “energy density,” or
that have a lot of calories in a small amount of food.
For example, a large cheeseburger with a large order of fries may have almost 1,000 calories and 30 or more grams of fat.
By ordering a grilled chicken sandwich or a plain hamburger and a small salad with low-fat dressing, you can avoid hundreds of calories and eliminate much of the fat intake.
For
dessert, have fruit or a piece of angel food cake rather
than the “death by chocolate” special or
three pieces of home-made pie.
Remember that much may be achieved with proper choices in serving sizes.
Accumulate at least 30 minutes or more of moderate-intensity activity on most, or preferably all, days of the week.
Examples of moderate intensity exercise are walking a 15-minute mile, or weeding and hoeing a garden.
Look for opportunities during the day to perform even ten or 15 minutes of some type of activity, such as walking around the block or up and down a few flights of stairs.
Always consult your physician for more information.
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