Aim for a variety of nutrient-rich whole plant foods

Answering Your Questions on Diet for Cancer Prevention & Survivorship

When you have over 470 people gathered, it’s hard to answer everyone’s questions.  That’s how many people tuned in this week for the American Institute for Cancer Research (AICR) webinar, Diet & Physical Activity in Cancer Prevention & Survivorship: The Science and Practice. 

We shouldn’t be surprised that program time ran out before we could get to anywhere near all the questions from such a large group on an exciting and ever-evolving topic like this. We’ll be looking at how we can address these questions in a variety of formats in the future.  Meanwhile, today I’ll get a start and answer a few of the many excellent questions posed….

In the webinar, Cheryl Rock, PhD, RD, a renowned researcher leading major studies on promoting the health and wellbeing of breast cancer survivors, provided insights to help participants (mainly health professionals) interpret previous studies on diet, physical activity and cancer.  Dr. Rock shared some of the details of the studies that are key to understanding their results. As I often say, you can’t go by a study’s title, the media blast about it or even its abstract (brief summary) and think you’re getting the whole story.

I presented the second half of the webinar, reviewing research behind current recommendations to reduce cancer risk and their practical implications.

So, now to a few of your questions….

What foods support the colon bacteria that seem to be cancer-protective?

In the webinar, I talked a bit about the booming field of research involving how the trillions of bacteria in our gut may help reduce cancer risk.  A strong colony of healthy bacteria seems to promote immunity and prevent growth of bacteria that produce cell-damaging substances associated with inflammation. These health-promoting bacteria produce substances that protect colon cells, and in many cases are absorbed out of the colon and circulate through the body providing apparent cancer-protective benefits.

 Certain types of carbohydrate are used to produce a fatty acid called butyrate, which seems cancer-protective in the colon. Bacteria use and are nourished by inulin (which we get from onions, garlic, asparagus, Jerusalem artichokes, bananas, chicory and artichokes) and the fermentable dietary fiber and resistant starch you get from dried beans and peas and certain whole grains.

 Compounds called lignans from beans, whole grains, nuts and seeds are converted to a form that can be absorbed. As they circulate through the body, they seem to have protective effects on estrogen hormones and anti-cancer effects on cell metabolic pathways.

Phytochemicals, such as the glucosinolates from cruciferous vegetables, and ellagic acid from fruits and walnuts, are converted, respectively, to active and absorbable isothiocyanates and urolithins. Laboratory studies suggest they may reduce cancer as antioxidants and through direct effects.

Diets high in red meat seem to inhibit growth of health-promoting bacteria and  stimulate growth of bacteria that promote production of sulfate compounds that damage colon cells.

For people who have lost healthy bacteria due to certain health conditions, surgery or particular medications, probiotics — food and supplements that provide healthy types of bacteria — seem to help. These include fermented dairy products (yogurt, cheese, and kefir), sauerkraut, kimchi (a spicy Korean condiment made from fermented cabbage) and the fermented soy products miso and tempeh.  However, studies show that probiotics alone don’t change gut bacteria long-term nearly as much as when other dietary choices support growth of healthy bacteria, and their impact on cancer is not clear at this time.

What role does a gluten-free or lactose-free diet play in reducing cancer risk?

For those who have celiac disease or other gluten sensitivities, strict adherence to a gluten-free diet seems to be vital to protect the colon from damage that could increase risk of cancer.  However, for others, research shows no advantage to avoiding gluten, and whole-grain foods containing gluten can be good sources of a variety of antioxidant phytochemicals that may be cancer-protective.  Research also shows no reduction in cancer risk by avoiding foods with lactose (dairy products) by those who are not lactose intolerant.  In fact, quite a few studies link consumption of dairy products with lower risk of colon cancer.

Is grass-fed beef included in the recommendation to limit red meat?

Yes. Grass feeding increases meat’s content of omega-3 fat two- to four-fold compared to grain feeding. However, compared to the amount of these fats we get from eating eight to twelve ounces of fish per week, the 0.02 to 0.03 milligrams (mg) in a three-ounce portion of grass-fed meat is extremely small, so the importance of this difference is not yet clear. Some analysis reports grass-finished beef contains as higher in CLA (conjugated linoleic acid) as grain-finished beef, but results on this are inconsistent, as is the cancer protection beyond that seen in preliminary lab studies.

Current research suggests a key reason for the link between risk of colon cancer and excessive amounts of red meat consumption is the high content of a particular form of iron in red meat, called heme iron.  This iron is very easy for the body to absorb, which is an advantage for people not getting enough iron in their diet.  However, this heme iron can also promote formation of certain carcinogens within the gut, cause direct damage to colon cells and generate highly reactive free radicals that can damage cell DNA and begin cancer development. Since grass-fed beef and lamb are just as high in heme iron as grain-fed forms, they are also included in the recommended limit of no more than 18 ounces (cooked) red meat per week.

By the way, the correct term in discussing this is “grass finished”.  All beef comes from cattle that graze on pasture most of their lives. Conventionally produced beef (“grain finished”) comes from cattle that spend the last four to six months of life in a feedlot eating a mixture of grains and soybeans, whereas “grass-finished” beef comes from cattle that spend their entire lives feeding on pasture. People choose grass-finished beef for a variety of reasons, but we really don’t know yet how much health impact the difference in fat content provides.

With all the steps identified to lower cancer risk through eating and lifestyle choices, how do we set priorities?

This may be the most important question of all.  Through the webinar we tried to provide participants with state-of-the-science information regarding many ways our food and physical activity choices can increase or decrease cancer risk.  Science is clear that we don’t need to live “perfect” lifestyles to make a major difference in our risk.

We do need to stay focused, and make sure that regardless of where the world’s hype focuses at any given moment, we keep focused on the choices that matter most.  The AICR Guidelines form an excellent basis for that focus:

Choose mostly plant foods, limit red meat and avoid processed meat.  Make vegetables, fruits, whole grains and beans the largest part of your plate each time you eat.  Focus on variety in your vegetables, and choices that are not processed in ways that remove nutritional value or add excess calories and sodium.  And learn to prepare these so deliciously and easily that they are not just part of your eating when you’re “on a diet”, but become the highlight of your meals.

Be physically active every day in any way for 30 minutes or more.  Forget about how many calories you burn and what that entitles you to eat.  Regular physical activity is key to supporting long-term weight control, but you won’t see that after one walk, or even one week of walks.  Whether or not you walk (or get other activity) today impacts levels of insulin and other hormones and growth factors that affect cancer risk today. Every day’s movement matters.

Aim to be a healthy weight throughout life.  Cancers that are among our most common, like colorectal and breast cancer, and most deadly, like pancreatic cancer, are related to excess body fat.  If you’re far beyond recommended weights, you may think it’s too late to matter, but losing even 15 or 20 pounds (and keeping it off) makes a difference in the hormones and inflammation that promote cancer development. If you think that your weight is still “ok” despite gaining 15 pounds and watching an expanding waistline, research suggests you, too are at risk and should take action now.

Add up changes that total about 500 calories per day cut from current habits by decreasing portions and avoiding sugar-laden drinks, and substitute bigger portions of vegetables so you won’t go hungry.  Find some small changes and make them today. Don’t wait for perfection.

Thanks to all of you who joined us for the webinar.   A big thank you goes out to the California Walnut Commission for sponsoring the webinar.  AICR is planning to post the webinar on its website. Stay tuned here and at the AICR website for further updates and plans to address your many important questions on this vital topic.  Please comment below with questions you’d like me to address here in the future.  I love to give presentations to groups of health professionals, cancer survivors and “regular folks” who want to know about what today’s research shows about how we can lower our cancer risk.  You can reach me through the Contact section of my website regarding my availability for speaking engagements.

 

2 Comments

  1. Dr Frank Yap on May 23, 2012 at 11:48 am

    Thanks for the tips on cancer prevention.

    Famous People | Celebrities | Cancer Deaths | Prevention

    • Karen on May 24, 2012 at 12:14 am

      Thank you for the positive feedback. The challenge is how to get out the message that we can change cancer risk and that the lifestyle that does it is not the burden that many people expect. We can make choices that add up to a lifestyle that promotes good health!

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Meet the author/educator

Karen Collins
MS, RDN, CDN, FAND

I Take Nutrition Science From Daunting to Doable.™

As a registered dietitian nutritionist, one of the most frequent complaints I hear from people — including health professionals — is that they are overwhelmed by the volume of sometimes-conflicting nutrition information.

I believe that when you turn nutrition from daunting to doable, you can transform people's lives.

Accurately translating nutrition science takes training, time and practice. Dietitians have the essential training and knowledge, but there’s only so much time in a day. I delight in helping them conquer “nutrition overwhelm” so they can feel capable and confident as they help others thrive.

I'm a speaker, writer, and nutrition consultant ... and I welcome you to share or comment on posts as part of this community!

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