Just 25 to 29 grams of fiber a day can add years to your life, conclude the authors of a major new analyses.
Dietary fiber doesn’t have the most glamorous reputation. Unlike the pizzazz of so-called superfoods and the visual feast of eating the rainbow, humble fiber has mostly been relegated to the realms of “what to eat to stay regular.” Hello, prunes, hi there, bran.
But while you are not likely to see sexy shots of food on Instagram exuberantly hashtagged with #fiber, maybe fiber’s time is coming. I mean, if the once-maligned kale and Brussel’s sprouts can become rock stars, why not fiber? And especially now, given new research once again confirming fiber’s seriously impressive benefits.The research was commissioned by the World Health Organization and looked at carbohydrate quality and human health. Fiber is the all-important nondigestible component of plant food and is an important part of the carbohydrates we consume. And unfortunately, it is all too often removed in processed foods – think white bread versus whole-grain bread, or fruit juice versus whole fruit.
The researchers conducted a meta-analyses of 185 prospective studies and 58 clinical trials, which included a total of 4,635 adult participants. It’s a fascinating study (if you swing that way, writer raises hand), but for now I’ll just cut to the chase and reveal the findings.
When comparing those who ate the highest amount of dietary fiber with the lowest consumers, they found:
A 15 to 30 percent decrease in:
1) All-cause and cardiovascular related mortality
2) Incidence of coronary heart disease
3) Stroke incidence and mortality
4) Type-2 diabetes
5) Colorectal cancer
When comparing higher with lower intakes of dietary fiber, clinical trials showed:
6) Significantly lower bodyweight
7) Significantly lower systolic blood pressure
8) Significantly lower total cholesterol
The golden number for risk reduction was between 25 grams and 29 grams. But they also found that eating 30 grams or more “could confer even greater benefit to protect against cardiovascular diseases, type 2 diabetes, and colorectal and breast cancer.”
As nutritionist Leslie Beck explains in The Globe and Mail:
“Fibre-rich whole foods retain much of their structure in the gut, which helps promote satiety and weight control. Fibre in the gut also reduces the absorption of cholesterol into the bloodstream and slows the rise in blood sugar after eating.”
The researchers only considered naturally occurring fiber – not fiber that was added to food (which food makers do to boost nutritional labels) or fiber taken as a supplement.
The U.S. FDA says that most Americans do not get the recommended amount of dietary fiber, calling it a "nutrient of public health concern" because low intakes are associated with potential health risks.
Current U.S. guidelines for fiber are 25.2 for females ages 31 to 50 and 30.8 grams for males 31 to 50 (to see other ages, go to page 43). Meanwhile, the Daily Value listed on nutrition labels is for 25 grams per day, based on a 2,000 calorie diet.
There are two types of dietary fiber – most plant foods contain some of each, and both are important. The FDA defines them as such:
Soluble fiber dissolves in water to form a thick gel-like substance in the stomach. It is broken down by bacteria in the large intestine and provides some calories. It can be found in beans and peas, fruits, oats (like oat bran and oatmeal), nuts and seeds, vegetables, and more.
Insoluble fiber does not dissolve in water and passes through the gastrointestinal tract relatively intact and, therefore, is not a source of calories. It can be found in fruits, nuts and seeds, vegetables, wheat bran, and whole grain foods (such as brown rice and whole grain breads, cereals, and pasta).
Here is a random sample of fiber amounts (taken from the FDA's chart found on pages 46 and 47 here) to give you an idea of what you may be eating and where to get more.
High fiber bran ready-to-eat cereal: 1/2 cup serving – 9.1 to 14.3 grams
Cooked navy beans: 1/2 cup serving – 9.6 grams
Canned chick peas: 1/2 cup serving – 8.1 grams
Fresh pear: Medium size – 5.5 grams
Avocado: 1/2 cup serving 5.0 grams
Green peas: 1/2 cup serving 3.5 to 4.4 grams
Raspberries: 1/2 cup serving 4.0 grams
Baked potato with skin: One medium – 3.6 grams
Whole-wheat spaghetti, cooked: 1/2 cup serving – 3.2 grams
Orange or banana: One medium – 3.1 grams
Basically, think whole grains, beans and pulses, vegetables and fruits – every day. A diet which also happens to be much better for the planet than plates full of resource-intensive animal products.
And all of that said, there's one last thing to keep in mind: Add fiber to your diet slowly. Bumping up your dietary fiber too quickly can lead to gas, bloating, and cramps – and in our quest to make fiber the sexy new nutritional star, stomach discomfort is not part of the plan.
The research was published in The Lancet.