by Over the past decades, many studies have investigated the relationship between individual foods and nutrients and breast cancer risk.
The results strongly suggest that some dietary components (eg, vegetables, fiber) are protective while others (eg, red meat, alcohol) can increase the likelihood of developing breast cancer.
However, these studies do not consider the combined effects of an overall dietary pattern in which foods, nutrients and other dietary components interact with each other.
Although researchers have studied dietary patterns and breast cancer risk, the World Cancer Research Fund (WCRF) and American Institute for Cancer Research (AICR) a joint expert report in 2018 concluded that the evidence for a link between the two was inconclusive.
Meanwhile, research suggests that a combination of healthy habits offers even better protection against breast cancer than isolated healthy lifestyle behaviors.
Now, findings from an updated comprehensive research review add to the growing evidence that this is the case, particularly for postmenopausal women. Here’s what you know.
The latest research
The updated review was part of the Global Continuous Update Project (CUP), an ongoing program that analyzes research on how diet, nutrition and physical activity affect cancer risk.
Evidence from new research is constantly being added to CUP. It is then assessed and interpreted by an independent panel of experts to make judgments and conclusions about cancer prevention.
The new CUP review, published online last month in the American Journal of Clinical Nutrition, included 84 studies spanning 22 years, most conducted in North America and Europe.
The researchers assessed the relationship between breast cancer risk and dietary pattern adherence alone or in combination with lifestyle behaviors.
Evidence of breast cancer risk was determined for all females (ie studies that did not specify menopausal status) and also separately for premenopausal and postmenopausal women.
A healthy lifestyle pattern brings more benefits
Overall, higher adherence to healthy lifestyle patterns including a healthy diet and other lifestyle factors was consistently associated with lower breast cancer risk and the evidence was graded “probably strong”.
Only results from studies of dietary patterns were more consistent and the evidence was assessed limited, meaning that it was suggestive or not conclusive.
Common dietary and lifestyle patterns were based on advice to maintain a healthy weight, be physically active, follow a healthy diet and consume moderate to zero alcohol.
Lifestyle patterns specific to cancer prevention (eg, WCRF/AICR and American Cancer Society lifestyle scores) have included certain dietary ingredients that have been linked to lower cancer risk.
However, only higher adherence to WCRF/AICR and American Cancer Society lifestyle patterns was consistently associated with lower breast cancer risk in all and postmenopausal women; the evidence was graded “strongly probable”.
Fewer studies were available on lifestyle patterns and breast cancer risk in premenopausal women; graded evidence was limited, but suggestive.
how diet can help guard against breast cancer
Healthy dietary patterns are thought to reduce inflammation and oxidative stress in the body, factors thought to play a role in the initiation and progression of breast cancer.
Adhering to a healthy dietary pattern may also help control insulin and insulin-like growth factors, hormones associated with breast cancer risk.
What is (and isn’t) a cancer-preventive dietary pattern
An eating pattern linked to a lower overall cancer risk is centered around plant foods – vegetables, fruit, whole grains (at least half of your daily grains), beans (including soybeans) and lentils.
When it comes to vegetables and fruits, the American Cancer Society recommends eating 2.5 to 3 cups of vegetables and 1.5 to 2 cups of fruit every day. That’s similar to the Canadian Cancer Society’s recommendation to fill half your plate with vegetables and fruit at every meal.
Diversity is also important.
To eat a wide range of protective nutrients and phytochemicals, include dark green (eg, spinach, rapini, arugula), orange (eg, carrots, sweet potato, winter squash), cruciferous (eg, broccoli, cauliflower, Brussels sprouts) and allium. (eg, garlic, onions) vegetables. Vary the types of fruit in your daily diet.
A diet rich in plant foods is also high in fiber. The WCRF and AICR recommend consuming at least 30 g of fiber each day from whole foods.
Red meat is limited to three servings per week (12 to 18 ounces total). Processed meat should be eaten sparingly, if at all.
Ultra-processed foods (eg, fast foods, commercial baked goods, ready-to-eat foods or ready-to-heat foods) will be limited. Sugar-sweetened drinks should be avoided.
To prevent cancer, it is best not to drink alcohol. If you choose to drink, the Canadian Cancer Society recommends no more than two standard drinks per week (one standard drink is 5 ounces of wine, 1.5 ounces of 40 percent spirits or 12 ounces of 5 percent beer).
Leslie Beck, a private practice dietitian based in Toronto, is the director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD
