do fructose, polydextrose, resistant
starches and dietary fiber. These ingre-
dients are used extensively to complete-
ly or partially replace sucrose, glucose
and high-GI polysaccharides such as
starch and maltodextrin in a wide range
of processed foods, including dairy
products, baked goods and confec-
tionery. The glycemic responses and
other properties of a range of carbohy-
drates are summarized in Table 1. It
should be noted that these carbohy-
drates may alter glycemic response but
not glycemic index, according to the
strict definition.
Carbohydrates differ physiologically
in that some are hydrolyzed and
absorbed from the small intestine and
are then metabolized in the body tissues
(e.g., glucose, fructose, sucrose, cooked
starch); some are incompletely
hydrolyzed and/or absorbed and metab-
olized (e.g., lactose, isomalt, sorbitol,
xylitol); some are absorbed, not metab-
olized and excreted via the urine (e.g.,
erythritol, mannitol); some pass through
the small intestine unchanged and are
fermented completely or partially by
gut bacteria (e.g., polydextrose, pectin,
fructo-oligosaccharides, inulin, resistant
maltodextrin, resistant starch); and
some pass through the digestive tract
unchanged and are barely fermented
(e.g., cellulose).
Definitive studies specifically
addressing the role of low-glycemic
carbohydrates in disease risk reduction
are few. A recent review of the health
potential of polyols as sugar replacers
places emphasis on low-glycemic prop-
erties. The same author also presented a
meta-analysis of relevant studies,
focusing on the impact of GI (or,
strictly speaking, glycemic response)
on glycated proteins, particularly
HbA1C, at the 2005 Leatherhead Food
International Forum, Surrey, England.
Based on data linking HbA1C to car-
diovascular disease incidence, he con-
cluded that a reduction in glycemic car-
bohydrate equivalent to 30 grams of
glucose per day could correlate with a
30% reduction in cardiovascular dis-
ease risk. This reduction should be
achievable by most consumers, and
specialty carbohydrates could assist.
Challenges and opportunities
In time, the scientific community
may conclude that overall insulin
demand is a key determinant of disease
risk. This, in turn, largely correlates
with the glycemic impact of the diet.
There are exceptions, but overall
glycemic impact remains a useful
marker of physiological challenge.
Traditionally, GI has been used to com-
pare only "available" carbohydrates
where "available" means "absorbed
into the bloodstream in the upper gas-
trointestinal tract and metabolized."
Glucose, white bread and rice have
typically been used as standards, with
current preference for glucose as it is
easier to define. Currently, GI is the
parameter that is increasingly being
recorded on food labels and promoted
to consumers. If the traditional defini-
tion of GI prevails, consumers would
not gain a full impression of how to
reduce the glycemic impact of their
diet. Some foods, such as carrots, have
a high GI but low glycemic load.
Certainly it is not realistic for con-
sumers to understand the many differ-
ent terms associated with the glycemic
properties of foods. Given that only
one term is likely to reach the public's
perception, it is important that this
term is defined in such a way that it
has the most relevance for consumer
health. One researcher who intro-
duced the term "Glycemic Glucose
Equivalents" recently discussed this
point and argued for the extension of
the GI concept to foods. This may be a
way forward that could benefit con-
sumers. Indeed, the concept has recent-
ly been adopted by Atkins Nutritionals
as the "Net Atkins Count," and other
recent reviews also exist.
Several popular books are raising
consumer awareness of GI as a strat-
egy for improved nutrition. Of these,
"The Glucose Revolution" by Brand-
Miller et al. is currently in its 3rd edi-
tion. Rick Gallup recently published
"The GI Diet," which makes a useful
attempt at communicating the GI
concept to consumers. However, GI
should not be seen as a diet, but
rather a strategy for improved nutri-
tion that becomes a lifestyle choice.
Consumers will only derive maxi-
mum benefit from GI if food labels
can be devised that accurately convey
the relevant information. In turn, leg-
islators and regulators will only mod-
ify labeling if scientific substantia-
tion has been achieved. All those
involved acknowledge the need for
additional studies to fully elucidate
the impact of glycemic reduction on
disease risk in healthy populations.
The next step should be to undertake
definitive studies to improve our
knowledge in this area.
While definitive proof of the role of
GI may be some way off, there is a case
that, in the meantime, consumers should
be given the necessary information and
food choices to enable them to reduce
the glycemic impact of their diet if they
choose to do so. There is little downside
to this approach.
With a reduction in the glycemic
impact of the diet, a reversal in the trend
toward lifestyle-related diseases may be
observed. It has been estimated that the
glycemic challenge of our diet today is
typically 10 times as high as it was pre-
industrial revolution, and it is easy to
imagine that our bodies have found it
difficult to adapt.
Beth Hubrich, R.D., is executive director
of the Calorie Control Council and serves
as director of health and nutrition commu-
nications for CaloriesCount.com, the
Council's online dieting toolkit. Lyn
O'Brien Nabors is president of the Calorie
Control Council and has been with the
Council for over 25 years. To view the
bibliography for this article, go to
www.foodproductdesign.com.
Reprinted with permission from Food Product Design, July 2006
©2006 Virgo Publishing. All Rights Reserved.
