Polydextrose and Soluble Gluco Fiber as a dietetic aid to reduce the risk of type 2 diabetes mellitus.

The prevalence of obesity and insulin resistance appear to increase in the
European population, and they are two important components of the metabolic
syndrome. These metabolic abnormalities increase the risk of type 2 diabetes
mellitus (T2DM) and cardiovascular disease (CVD).
Both genetic and environmental factors (physical activity and diet) play an
important role in the etiology of these chronic metabolic diseases. Obesity
develops as a result of an imbalance between energy intake and energy
expenditure, resulting in a positive energy balance. Although many factors
promote a positive energy balance, there is sound evidence that a western diet
rich in a large amount of rapidly available carbohydrates (cooked starches) and
added refined sugars (sucrose, high fructose corn syrup) may be
counter-productive to body weight control and glycemic control.The latter
because they markedly increase postprandial glycemia and insulinemia, thereby
inhibiting adipose tissue lipolysis and/or muscle fat oxidation and, as such
may promote fat storage in both adipose and non-adipose tissue. Greater
postprandial fat storage in non-adipose tissue, such as skeletal muscle and
liver tissue, has been associated with the development of insulin resistance,
whilst postprandial hyperglycemia per se is a strong risk factor for the
development of T2DM and cardiovascular comorbidities. Finally, hyperinsulinemia
may actually have less favourable effects on blood lipid profile. Potential
negative side effects of high carbohydrate diets may be counteracted by the use
of low glycemic index (GI) foods. The ingestion of slowly digestible
carbohydrates (soluble fibers) may attenuate postprandial glycemia, reduce
insulinemia, and enhance fat oxidation, all of which may assist to prevent body
weight gain and insulin resistance. The use of low glycemic diets may be of
relevance in dietary strategies to modulate body weight, improve insulin
sensitivity and reduce cardiovascular risk.

Controlling the glycemic impact of food products may reduce glycemic and
insulinemic responses. This may result in a decreased inhibition of fat
oxidation rate and lower plasma TAG concentration. A higher postprandial fat
oxidation may result in less lipid accumulation in non-adipose tissues, thereby
improving insulin sensitivity and the metabolic profile in the longer term.
Therefore, the primary objective of the current study is to investigate the
effect of a reduction in glycemic load by the use of two different soluble
fibers (polydextrose and soluble gluco-fiber) on postprandial fat oxidation
rate. Secondary objectives are the differences in energy expenditure, substrate
oxidation of carbohydrates, plasma profile of free fatty acids (FFA) and TAG
and glucose and insulin responses.

In this project we will examine the effect of soluble fibers on postprandial
fat oxidation rate and plasma FFA and TAG concentration in a randomized
single-blind crossover design.
First, subjects will be invited for a screening visit and will be screened to
access eligibility.
Subjects with overweight (25<=BMI<=30kg/m2) and a fasting plasma glucose
concentration <7.0mmol/l will be included. Only if all the results from the
screening visit are in compliance with the inclusion criteria, subjects can
participate in the study.

20 subjects (men and women) will be studied four times with different dietary
interventions, in randomized order with at least one week in between. During
these periods, they will stay for 36 hours in the respiration chamber. After an
overnight stay in the respiration chamber, measurements will start for 24
hours. Glycemic profile (continuous blood glucose monitoring), energy
expenditure and substrate oxidation will be measured during the entire period.
Profile of insulin, FFA and TAG will be determined over a 14 h period during
day time by blood sampling before each meal (breakfast, lunch,diner) and 30,60,
120 and 240 min postprandial. The concentration hydrogen will be measured in
end-expiration (alveolar) breath samples every 2h from 8.00h until 22.00h and
again at 8.00h the next morning using a gastrolyzer* (Bedfont Scientific Ltd.,
The Netherlands).

On the four occasions, subjects will receive different dietary treatments,
which all consist of 48% of energy as carbohydrate, 37% of energy as fat and
15% of energy as protein.

A. a diet in which the test products contain polydextrose (PDX).
B. a control to diet A where similar test products are given without
polydextrose. The test products consist of full available carbohydrates and
there is no fiber added.
C. an isocaloric control to diet A where similar test products are given
without polydextrose. The test products are the same as for diet B, so with
full available carbohydrates and no fiber added.
D. a diet where part of the available carbohydrates in the test products are
replaced with Soluble Gluco Fiber (SGF)

Control diets B and C are necessary to investigate whether the effect of the
soluble fibers on fat oxidation rate is due to the lower caloric intake or the
ability of the fibers to increase the fat oxidation rate. In diet A and D, 30%
of the available carbohydrates at breakfast and lunch will be replaced by
respectively polydextrose or soluble gluco fiber.

Results of the study will provide insight if soluble fibers are capable of
improving postprandial fat oxidation. A higher postprandial fat oxidation may
result in less lipid accumulation in non-adipose tissues, thereby improving
insulin sensitivity and the metabolic profile in the longer term. Risks as the
result of participation in this experiment are minimal. Venapunctures can
occasionally cause a local haematoma or bruise to occur. Some participants
report some pain during venapuncture. Insertion of the CGMS could induce some
pain, however no discomfort is expected from carrying this device. Previous
studies have shown that wearing the CGMS does not hinder the subject in his
normal functioning. Also participants will be asked if they are claustrophobic,
because this could become a problem when they are staying in the respiration
chamber and will be excluded if no solution can be found. No harm from the
dietary intervention is to be expected. All diets used during this study are
provided by Tate and Lyle or purchased in the local supermarket and used
before indicated expiring dates. During the test days meals will be prepared in
the kitchen of the department of Human Biology which is solely dedicated for
preparing of food for human use.