愛污传媒

But according to a study published today in the Journal of the American Medical Association, more than "5-a-day" is not better. Our nutrition expert, Leslie Beck, tells us more about the study.

Q: Do we know what foods can help prevent breast cancer recurrence?

While literally hundreds of studies of food and nutrition have focused on cancer prevention, very few have examined the effect of lifestyle factors on cancer survival after diagnosis. When it comes to breast cancer recurrence, a handful of studies suggest that certain diet and lifestyle choices can improve survival. Studies have linked eating five daily servings of fruits and vegetables, regular exercise, increased fibre, and reduced fat with greater likelihood of recurrence-free survival.

Q: Tell us about this new study...increasing fruits and vegetables beyond five servings per day was not protective?

What the study found was that if you increase your intake of fruits and vegetables from five to 12 servings per day, there's no additional protection from breast cancer recurrence. In the study (The Women's Healthy Eating and Living Study), researchers from the University of California, San Diego, assessed whether a diet very high in vegetables, fruit, fibre and low in fat would reduce the risks of recurrent breast cancer and all-cause death among women previously treated for early stage breast cancer. The intervention group received a telephone nutrition counseling program and cooking classes that promoted daily targets of 12 fruit and vegetable servings (five vegetable servings, 16 ounces of vegetable juice, and three fruit servings), 30 grams of fibre, and 15 to 20 per cent of calories from fat.

Women in the comparison group received pamphlets recommending a daily diet with five servings of vegetables and fruit, more than 20 grams of fibre, and less than 30 per cent fat calories.

After 7.3 years of follow up, there was no difference between the two groups in either additional breast cancers or prolonged life. In both diet groups, 17 per cent of women were diagnosed with a breast cancer and 10 per cent died (more than 80 per cent of deaths were due to breast cancer).

Q: Does this mean that women should stop trying to increase their fruit and vegetable intake?

No. These findings should not be interpreted to mean that eating more fruits and vegetables doesn't help to reduce the risk of breast cancer recurrence. This study didn't test whether moving from a diet with little or no fruits and vegetables to a pattern of eating five or more daily servings improved survival. Rather, the results say if five servings a day is good for you, '12-a-day' doesn't offer extra protection. In other words, you don't have to have a super-normal fruit and vegetable intake to protect yourself from future cancer.

While this study found no overall benefit from increasing fruits and vegetables to 12 servings per day, there may be differences between subgroups of women. It's possible that age, ethnicity, and genetics determine the effectiveness of dietary factors on breast cancer risk.

There are other good reasons to eat more than five servings of fruits and vegetables per day. There's more than breast cancer that women need to be concerned about: Canadian women are more likely to die from heart disease than from any other disease. Exceeding the five-a-day advice can lower blood pressure and, presumably, reduce the risk of stroke. The Dietary Approaches to Stop Hypertension (DASH) randomized trials demonstrated a potent blood pressure lowering effect from eating eight to 10 fruit and vegetable servings per day. And based on the scientific evidence linking higher intakes of fruits and vegetables to protection from cancer and heart disease, the newly revised Canada's Food Guide (2007) now advises Canadian women to consume seven to eight servings per day.

Q: Any other nutrition tips for breast cancer survivors?

Studies suggest the following tips can reduce the risk of breast cancer recurrence.

Eat more vegetables and fruit. Strive for at least five servings per day. Studies suggest that cruciferous vegetables (broccoli, Brussels sprouts, cabbage, cauliflower) and leafy greens are especially protective from breast cancer.

Reduce fat intake. Based on findings from the Women's Intervention Nutrition Study, a randomized controlled trial that enrolled 2,437 postmenopausal women within one year of diagnosis of early stage breast cancer, it is prudent to eat less fat. The study found significant improvement in survival among women assigned to a low fat diet (15 per cent of total calories or 33 grams of fat per day).

Choose lean meats, poultry breast, legumes and non-fat dairy products. Use higher fat spreads and salad dressings sparingly.

Control your weight. Breast cancer survivors who are overweight or obese are more likely to have their cancer recur compared to thinner survivors. Women are advised to keep their body mass index (BMI) in the range of 18.5 - 25 and limit adult weight gain to 11 kilograms (5 pounds).

Be active. Moderate exercise, such as walking a few hours per week, has been shown to improve breast cancer survival. In a study published last month, walking 30 minutes six days per week - combined with eating five or more fruits and vegetables - reduced breast cancer death by 46 percent.

Drink green tea. There's preliminary evidence that drinking three to five cups of green tea per day may help prevent breast cancer recurrence in early stage cancers.