Karen Collins
What’s “new” in cancer prevention recommendations? No, it’s not a new study that turns what we previously thought upside down. It’s a new report from a panel of experts on how diet, weight and physical activity influence cancer. The report adds yet another set of voices with a consistent message: paying attention to a few basic choices in relation to what you eat and drink and in how much you move can add up to make a real difference in your risk of getting cancer.
Different panels of experts have studied the best available evidence and have come to strikingly similar recommendations about eating habits, physical activity and weight (body composition) that can influence someone’s cancer risk. For health professionals like me, the alignment of this new cancer prevention guideline from the American Cancer Society (ACS) with the previously published recommendations of the American Institute for Cancer Research (AICR) provides even greater confidence that the advice we give is pointing in the right direction.
Strongest Steps for Cancer Prevention
What’s the most important message about cancer prevention we should take away from this new ACS guideline? My registered dietitian nutritionist colleague, Colleen Spees, PhD, RDN, Associate Professor of Medical Dietetics at The Ohio State University College of Medicine, served as a member of the panel developing the new guideline and a co-author of the new paper. She says, “This updated guideline reinforces the key recommendations from other reputable organizations…promoting energy balance for weight control, consumption of a plant-focused dietary pattern, engaging in regular physical activity and limiting sedentary time. This updated guideline also encourages avoidance of alcohol when possible.”
Weight that reflects overweight and obesity is strongly linked to greater risk of many relatively common cancers. Don’t let this merge with society’s messages urging everyone to aim to be “beach body” thin in order to be healthy or attractive. Recommendations to avoid adult weight gain and maintain a healthy weight and waist size refer to avoiding the harmful effects of excess body fat on hormones like insulin and estrogen, inflammation and oxidative stress. The new report emphasizes, “…only cigarette smoking accounts for a higher percentage of cancer cases” than overweight and obesity.
But what if you’re already carrying excess body fat? We need more research to understand how intentionally losing some pounds can affect cancer risk, but studies are clear that losing and maintaining a modest reduction in body fat can improve markers of metabolic health. So considering the clear benefits of modest weight loss for reducing risk of heart disease and type 2 diabetes, the new ACS report concludes that people with overweight and obesity should be encouraged and supported to reduce their weight.
Physical activity is a powerful way to promote health, including lowering risk of cancer. Both ACS and AICR explain that physical activity can thwart cancer development through effects on insulin and glucose metabolism, immune function, inflammation, sex hormones and more. Both organizations say that 150 minutes of moderate physical activity (equivalent to brisk walking) should be a minimum target. More than that is likely even better for cancer prevention.
What if you’re one of the many Americans who don’t get nearly that much movement on a regular basis? Again, the message is consistent: the greatest reduction in cancer risk occurs when people change from no moderate physical activity to any amount. Whatever your starting point may be, move more and sit less.
Diet, in reports like these, does not refer to some strict set of rules you follow temporarily. Diet refers to your whole pattern of eating – what you eat and drink, how it’s fixed,and how big your portions are.
You may notice that the ACS and AICR reports organize the recommendations about diet a little differently. But if you look closely, the actual choices that are encouraged and discouraged are completely consistent. Center your eating to emphasize a variety of vegetables, fiber-rich pulses (dried beans and peas), fruits and whole grains. Limit or avoid red and processed meats, sugar-sweetened drinks and highly-processed foods. To clarify, processed foods like chopped, canned and frozen vegetables are fine, and can make it easier to achieve recommended food choices. The “red flag” foods are highly-processed in ways that remove valuable nutrients, phytocompounds and fiber; add large amounts of unhealthy fats, sugars and sodium; or both.
Questions and Misconceptions about Reducing Cancer Risk
Why is there so much talk about dietary patterns instead of specific vitamins and other nutrients?
“The focus on dietary patterns, in contrast to individual nutrients and bioactive compounds, is more consistent with a food-first philosophy and what and how people actually eat,” says Spees. She emphasizes that people eat foods. Individual nutrients may each have effects that contribute to higher or lower cancer risk, but these effects are small. As part of overall eating habits, nutrients and natural compounds in food can add up or even interact synergistically to influence cancer risk.
“It’s best not to drink alcohol.” What does that mean?
This is a consistent recommendation from the new ACS report, as well as from AICR. Both leave room for personal choice, noting that if you do choose to drink alcohol, it’s important to limit amounts to meet official definitions of moderation. These set a cap at no more than one standard drink per day for women and no more than two standard drinks per day for men. But based on strong research evidence, if the only factor in your decision was reducing cancer risk, the answer would clearly be to skip the booze.
If you didn’t know this, surveys show you’re not alone. Yet, as alcohol is metabolized, carcinogenic (cancer-causing) compounds form. And the more alcohol a person drinks, the more his or her risk rises for several different cancers, with breast cancer risk rising at even modest consumption.
Additional Guidance for Cancer Prevention
The new ACS report includes two additional sections beyond the discussion of the four key recommendations for individuals.
A guide to common questions about topics like coffee, genetically modified (GMO) crops, non-nutritive sweeteners, organic foods and vegetarian or vegan diets – what did this panel of experts conclude? Spees says, “There just is not enough evidence specific to cancer prevention currently available” to include these topics in the main guideline. Since people often ask about them, this separate section is included “to provide the state of the available evidence to help guide their individual decisions.” Of note, the AICR expert panel likewise found evidence too limited in amount and or quality to address any of these in its recommendations. As a dietitian providing guidance to people, I feel more confident doing so noting that the ACS and AICR panels came to similar conclusions on each of these. For example, here’s where you can find AICR messages on coffee, organic foods and vegetarian and vegan diets.
The tough question: what will it take for more of us to create a healthy lifestyle?
Spees points out that the ACS guideline includes a call for community action to guide the translation of these recommendations to the individual, local, state and national levels. Included are ideas for how communities can increase access and affordability of healthy foods at home and away from home. It also calls on communities to look at how the built environment – roads, walking and bicycle routes and land use – can make a difference in making it easier to be physically active as recreation and daily transportation. Taking a fresh look can reveal new ideas for how facilities in a community can support community health. AICR has also long advocated for creating communities that support healthy lifestyles.
So with this new report, the foundation has grown stronger and more consistent identifying opportunities that we can take, as individuals and as communities supporting one another, to reduce the burden of cancer.
