This article is a part of a larger feature: Satiety:Feeling Full and Satisfied.
Intake of fiber has long been associated with feeling full and reduced food intake, based on its increasing digestive viscosity, but it is has also recently been proven an important regulator of ghrelin levels.1
There has been a longstanding theory that high-fiber foods are more satiating than foods with little or no fiber, but researchers have more recently sought to determine if certain types of dietary fiber enhance satiety more than others. In 2007, University of Toronto researchers reported 33 g of insoluble fiber reduced appetite, lowered food intake and reduced glycemic response to a meal consumed 75 minutes later, compared to a low-fiber placebo.2 The team continued their investigations, reporting in 2009 a high-fiber (22 g insoluble) cereal was more effective than a low-fiber (1 g) cereal at reducing energy intake at lunch, possibly due to a high-satiety value per kilocalorie in the high-fiber cereal.3
Insoluble fiber also benefits appetite control in hospital patients receiving enteral nutrition (tube feeding). London-based researchers reported consumption of a formula containing 10 g/L of pea fiber and 5 g/L of fructo-oligosaccharide (FOS) insoluble fiber resulted in higher mean fullness, minimum fullness and minimum satiety, compared to the standard enteral formula.4
The latest research on FOS and satiety demonstrated healthy adults taking 21 g/d of FOS for 12 weeks experienced greater reduction in body weight than the placebo group.5 Researchers further noted FOS had a positive effect on glucose levels, as well as both ghrelin and PYY, which coincided with a drop in calorie intake.
In 2009, scientists from Unilever reported results of their latest trial on insoluble FOS and oat beta-glucan, a soluble fiber.6 Healthy volunteers were given food bars containing either 0.3 g of oat glucans (control), 0.9 g of oat glucans, 8 g of FOS or both fiber amounts combined. Two days of consumption of FOS, oat glucans or the combination all failed to affect appetite, although researchers admitted the results could have been more positive if oat beta-glucan content were higher or a different glucan type were used.
One Hot Topic Joins Another
From the increasingly popular world of probiotics may come the next ingredient for hot category of satiety supplements. After researching numerous strain of Lactobacillus casei, Chr. Hansen has found one strain that demonstrated significant effects on satiety via a mechanism involving hunger hormones. The company expects its completed and ongoing research will be published sometime next year after the company secures the relevant patent protection. This L. casei product, branded ProSat, appears destined for functional foods and beverage, in addition to the usual satiety supplements.
However, a 2009 study report out of Finland noted a beverage containing 10.5 g of fiber from a combination of wheat gluten and oat beta-glucans beverage increased fullness and perceived satiety, while decreasing the desire to eat, compared to a beverage without fiber.7 Incidentally, the same study showed a beverage containing 7.8 g of guar gum (soluble fiber) had the greatest impact on satiety and desire to eat.
Soluble fiber, including oat beta-glucan, has held its own ground in the quest to promote satiety. In 2007, Louisiana State University researchers reported 14 weeks of supplementation with 4 g/d of oat and barley beta-glucan soluble fiber (as ViscoFiber®, from Natraceutical Canada) resulted in weight loss and increases to fasting PYY, fasting GLP-1 and satiety at one hour following a standard meal.8
Likewise, fellow soluble fiber glucomannan, derived from the root of the elephant yam or konjac plant, has also shown promising effects on satiety. A 2007 trial out of Barcelona, Spain found a fiber mixture containing 1 g of glucomannan and 3 g of Plantago ovata husk taken twice or three times daily more effectively promoted postprandial satiety among 200 obese or overweight patients, compared to placebo.9
Still other soluble-fiber types have surfaced in research on satiety. In healthy men and women taking one of four types of high-fiber (8.0 to 9.0 g fiber) muffins or a low-fiber (1.6 g fiber) muffin for breakfast, muffins containing resistant starch and corn bran had the most impact on satiety;10 muffins containing polydextrose fiber had a minimal impact on satiety similar to that of the low-fiber muffins.
Soluble galactomannan fiber from fenugreek is starting to generate beneficial results on satiety. In 2009, University of Minnesota, St. Paul, scientists published results of a trial in which obese subjects ate a breakfast containing either 0 g, 4 g or 8 g of isolated fenugreek fiber.11 Ratings for hunger, satiety, fullness and prospective food consumption were recorded every half hour for 3.5 hours. The highest dose of fenugreek fiber significantly increased mean ratings of satiety and fullness, and reduced ratings of hunger and prospective food consumption, although these results were not related to postprandial blood glucose.
Another fiber starting to make its way into satiety science is galacto-oligosaccaride (GOS), a derivative of the milk sugar lactose. This probiotic fiber works via not only a bulking mechanism in the gut, but also by fermenting in the colon to increase production of short-chain fatty acids and boost production of satiety hormones such as PYY and ghrelin. Preliminary results from a trial on GOS (as Vivianl GOS, from Friesland Domo) showed a higher concentration of PYY, an appetite regulating hormone, in rats fed GOS. There was also a decrease in the daily energy intake for over two weeks.
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