Tuesday, July 6, 2010

Trendy Bytes: Fiber Invasion

Used with permission by the American Dietetic Association.

The food manufacturing industry has unloaded an arsenal of products boasting a high fiber content.  I'm sure you've seen them.  Not only can we get "double fiber" bread, but now we can also consume foods that aren't typical sources of fiber, such as yogurt, cottage cheese, and even water!  When these products first started invading the marketplace, my dietitian radar of skepticism was immediately raised.  Is this because I'm not a fan of fiber?  No, I definitely believe that fiber-rich foods offer a wealth of potential health benefits, including improved bowel regularity, blood glucose control, and cholesterol management.  Also, Americans are definitely not consuming enough fiber -- only about half of the 20-35 g/day that's recommended.  However, I'm more of a fan of foods brimming with naturally-occurring fiber over those that have been infused with isolated fibers, like inulin (from chicory root) or polydextrose. These are also known as functional fibers.

Here are 5 reasons why I favor naturally-occurring sources of fiber (eg, whole grains, legumes, bran, vegetables, fruits, nuts, and seeds) over foods spiked with functional fibers.
  • Processing alters the plant's natural structure.  Some earlier research suggests that the more refined the plant food, the less effective it may be at promoting health.  For example, one study found that as wheat-based foods became more refined, the greater the insulin and blood sugar response.  So frequently consuming these more refined products may make managing a health condition like type 2 diabetes more challenging.  Another study found that subjects had more difficulty with bowel movements when consuming finely ground wheat bran in comparison to those consuming coarse wheat bran.  Essentially, the more refined the plant food (and these isolated fibers are refined components of foods), the less benefit we may actually get from the natural form of the food.  So focus more effort on consuming foods that are less refined.
  • When we extract one component of a food (eg, fiber), we are missing out on a host of other valuable nutrients and phytochemicals that the original plant-based foods offer.  For example, we can obtain naturally-occurring sources of inulin from onions, bananas, leeks, asparagus, shallots, peaches, and garlic.  All of these contain a variety of valuable nutrients and phytochemicals.  Think of the possibilities!
  • When we purchase a product based solely on the marketing claims on the label, our attention may be diverted from some of the less nourishing ingredients.  For example, I had a client who wanted me to evaluate the new granola bars she'd been consuming for an occasional snack.  The label on the box highlighted that they were only "90 calories" and contained "35% of the Daily Value for fiber" (mostly inulin from chicory root extract).  However, upon closer investigation of the ingredient list, we found that the product was riddled with several sources of added sugar, contained few high quality ingredients, and was not a significant source of many other key nutrients. So look beyond the clever marketing claims!
  • These fiber-laced foods may be substituting other nutritious foods.  For instance, the high-fiber granola bars may replace a serving of vegetable or fruit that could be eaten as a snack instead.  Also, some people may lax up on their consumption of foods naturally high in fiber since they're getting fiber from the fortified foods.  Remember to consider what nutrients or phytochemicals we might be missing out on by doing this.
  • Little research has been conducted on the health benefit of these functional fibers.  The evidence that is available seems to be very weak in terms of their impact on optimizing health.  I don't necessarily believe that these isolated fibers aren't capable of promoting health like their naturally-occurring counterparts; however, the evidence doesn't support their widespread infiltration into the food supply just yet.  In fact, one recent research study suggests that higher intakes of isolated inulin may lead to mild gastrointestinal discomfort in the form of bloating and gas.  So it may be wise to practice moderation with these foods, especially if you already have GI disturbances. 
What do you think of these fiber-spiked foods?

    2 comments:

    Anonymous said...[Reply to comment]

    I am unable to tolerate foods with the "fake fiber" (inulin) added. I have extreme gas, bloating, cramping and pain after consuming those foods. I read labels carefully, and if it has inulin as an ingredient, I don't buy it.

    Michelle Loy, MPH, MS, RD said...[Reply to comment]

    @Anonymous Thank you for sharing! It's great to see people making wise food choices by reading their labels carefully!!

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