Ask The Dietitian: Get Your Facts Right on Fiber and Whole Grains

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During our recent webinar, there were nuanced questions on whole grains and fibers, and we were unable to get to them all. I will try to address some of the important questions that came up and I think deserve a fuller response. Why do nutritional messages about lowering cancer risk talk separately about fibers and whole grains? Doesn’t taking care of one automatically take care of the other? Which is more important to lower cancer risk – fiber or whole grains? Whole grains are an important source of dietary fiber, and both are linked to a lower risk of colorectal cancer. So there is an overlap between the two. In other words, each offers distinctive benefits, and it is important to consider how you include each in your everyday eating habits.

Dietary Fiber
AICR recommends getting at least 30 grams of dietary fiber each day as part of a healthy eating pattern to lower cancer risk. The latest AICR report shows that each 10-grams increase in dietary fiber is linked with a 7 percent lower risk of colorectal cancer. It’s possible that fiber also plays a role in lower risk of other cancers, but that evidence is still very limited.

American adults, on average, need to increase fiber consumption by 12 to 15 grams a day to meet AICR’s 30-grams recommendation.

What does it look like to boost fiber by 15 grams ?
Breakfast: Switch from juice to ½ to ¾ cup of fruit on cereal, sliced on toast or eaten out of hand:
+ 2 more grams of fiber
Lunch: Swap 2 slices white bread for whole-wheat bread: + 2 grams of fiber
Instead of potato chips, choose 1 cup of raw pepper strips or other vegetables: + 1 gram of fiber
Afternoon snack: Instead of a candy bar, tide yourself over with an ounces of nuts: + 2-4 grams of fiber
Dinner: Replace part of the chicken or meat in your stir-fry, chili or casserole with ½ cup of black beans or lentils: + 8 grams of fiber
TOTAL: 15-17 grams of additional fiber

In this example to increase fiber, notice that the added fiber does not come from just one kind of food. It makes the healthy fiber target a more realistic goal when choosing from the big picture of food sources. Besides, foods differ in the mix of fiber types they contain, and this variety provides you with the wide range of fiber’s benefits. Viscous fiber, fermentable fiber and insoluble bulking fiber, for example, each support different aspects of health.

Whole Grains
AICR recommends including whole grains in most meals as one part of a healthy eating pattern to lower cancer risk. The latest AICR report says evidence is strong that 90 grams (about 3 ounces) of whole grains daily reduce risk of colorectal cancer by 17 percent, and eating more seems to reduce risk even further.

Grain foods come in many different forms – bread, rice, pasta, hot and ready-to-eat cereal, and more. To measure the amounts of grains or whole grains someone eats, we refer to portions as “ounce-equivalents”. A one-ounce slice of bread or serving of ready-to-eat breakfast cereal counts as one ounce-equivalent. So does ½ cup of cooked pasta, rice, barley, quinoa or other cooked grains; or a 6-inch tortilla.

Recommendations for overall health also emphasize the need to eat more whole grains, with advice to choose them for at least half of all the grain products we eat each day.

The average American adult eats a little less than one “ounce-equivalent” of a whole grain each day. Although that’s an increase compared to 10 years ago, on average, adults need to increase whole grains by at least 2 “ounce equivalents” a day to meet current recommendations for overall health. And this would go a long way toward meeting AICR’s recommendation to include whole grains in most meals.

What would it look like to boost whole grains by 2 ounces a day?

Make any two of the swaps below, and you’ve done it. It’s so easy, try one or two more once this is routine!
● Switch from cereal that’s a refined grain to a whole grain (like oatmeal, shredded wheat or whole wheat flakes).
● Instead of white bread for sandwiches or toast, choose whole-grain bread.
● Swap white rice for brown rice (quick-cooking options are fine if you want to save time).
● In a casserole or mixed dish, instead of white rice or refined grain pasta, try a cooked whole grain like bulgur, quinoa, millet, sorghum, or farro. Though perhaps unfamiliar to you, they are delicious, and a fun way to add variety beyond your usual choices.
● For burritos and wraps, choose a whole-grain tortilla or other flatbread.
● Switch your go-to pizza order to a whole-wheat crust. Or get whole-grain pizza dough and make your own at home, where you can load it with lots of delicious vegetables and herbs.
● Choose toasted wedges of whole-wheat pita bread or whole-grain crackers to dip in hummus or vegetable-yogurt dips.

Whole grains are better than refined grains not only for dietary fiber, but also for vitamin E, magnesium, and selenium. In addition, whole grains provide plant compounds called polyphenols, which may help support antioxidant defenses and promote health in a variety of ways.

We need to increase both whole grains and dietary fiber for eating habits that reduce cancer risk and promote health. Although some choices you make can help accomplish both goals, it’s important to increase a variety of fiber-rich foods to get the types of fiber and nutrients each uniquely provides.

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    Karen Collins

    Author: Karen Collins

    Karen Collins, MS, RDN, CDN, is AICR’s Nutrition Advisor. Karen is a speaker, writer and consultant who specializes in helping people make sense of nutrition news. You can follow her blog, Smart Bytes®, through her website and follow her on Twitter @KarenCollinsRD and Facebook @KarenCollinsNutrition.

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