Chester J. Zelasko, Ph.D. |
May 13, 2008
The Westernized diet
lacks fiber. We process foods such as wheat or corn until there’s nothing
left and then try to put it back together. When the refined foods are
combined with the lack of vegetables and fruit in our diet, it’s no wonder
that we’re constipated and have digestive issues. Adding fiber to our foods
has been tricky because of taste and texture issues, but there’s a new fiber
in town and it’s got an impressive reputation. The fiber is inulin and it’s
the topic of this Newsletter.
What Is Inulin?
There are two basic types of fiber--insoluble and soluble. Insoluble cannot
be broken down, will absorb water, and adds bulk to the stool. Soluble fiber
can absorb water but in addition, it can be broken down by bacteria in the
gut. Inulin is this type of fiber.
Inulin is a fructose-based fiber rather than a glucose-based fiber such as
cellulose, which makes up the cell walls of plants. Just like cellulose,
inulin resists digestion because of the chemical bonds that hold the
fructose units together. Inulin is found in just about every vegetable and
fruit including bananas, wheat, and allium-containing vegetables such as
onions and leeks. One of the primary sources of inulin in supplement form is
Inulin is considered a prebiotic; that means that as it’s broken down by
bacteria in the gut, the fructose feeds the bacteria. In this case that’s a
good thing, because research has shown that it helps the colony of
Bifidobacteria in the colon (1). Bifidobacteria are a class of
bacteria that are beneficial to digestive-system health as well as immune
One of the great properties of inulin is that it can be produced in chains
of various lengths. The shorter chains are sweeter and can add sweetness to
food. The longer chains add texture to foods and give the mouth the texture
that resembles fat. However, whether short or long chain, both add fiber to
the diet. Inulin is odorless and tasteless, so it can be added to any liquid
without altering the taste. It can also be used in cooking and baking
without changing the beneficial attributes of the fiber.
The research on inulin has increased in recent years. The following are
summaries of research on inulin:
In a review article, Guarner reviewed the research on the benefits of inulin
for inflammatory intestinal disorders such as Crohn’s disease and irritable
bowel disease (2). Studies demonstrated a reduction in inflammation in
intestinal cells and the stimulation of beneficial bacterial colonies such
as Lactobacilli and Bifidobacteria.
In another study, subjects with chronic constipation were given 20 grams of
inulin in semi-skim milk every day for 20 days. Constipation and associated
factors were significantly reduced in subjects taking inulin (3).
Clinical trials that have added inulin to infant formula have resulted in
significant improvement in the bacterial colony of the colon and a reduction
in the incidence of gastrointestinal and respiratory infections as well as
atopic dermatitis (4).
Inulin may be beneficial to serum lipids including reduced triglyceride
levels and total cholesterol (5).
You should eat your vegetables and fruit every day. But refined and
processed foods are not going away anytime soon, so it may be beneficial to
take a prebiotic soluble fiber that contains inulin. Depending on your diet,
5-15 grams per day should not cause any digestive issues such as loose stool
or cramping, but ramp up slowly. I’ve revised my fiber cocktail to include a
probiotic such as acidophilus, soluble fiber containing inulin, and
an insoluble fiber such as ground psyllium husks. Give it a try--your entire
body will love you for it.
- Gibson, GR. Dietary Modulation of the Human Gut Microflora Using the
Prebiotics Oligofructose and Inulin. J. Nutr. 129: 1438S–1441S, 1999.
- Guarner, F. Inulin and oligofructose: impact on intestinal diseases
and disorders. British Journal of Nutrition. 2005;93 Suppl1:S61–S65.
- López, R et al. The effect of a fibre enriched dietary milk product
in chronic primary idiopathic constipation. Nutr Hosp. 2008
- Veereman G. Pediatric applications of inulin and oligofructose. J
Nutr. 2007 Nov;137(11 Suppl):2585S-2589S.
- Jenkins, DA et al. Inulin, Oligofructose and Intestinal Function. J.
Nutr. 129: 1431S–1433S, 1999.