The effect of pre-treatment of bran on the bioavailability of ferulic acid and other bioactive compounds from wholegrain breads enriched in bran

Whole grain consumption has been associated with a lower risk of developing
metabolic syndrome, cardiovascular disease, type 2 diabetes and some type of
cancers. Whole grain is a good source of antioxidant compounds such as ferulic
acid, which has been considered its major antioxidant. Ferulic acid is also the
major phenolic compound in wheat grain, it is mainly located in the bran, more
precisely in the cell walls of the aleurone layer and overall bran layers. Most
of the ferulic acid is covalently bound to the indigestible cell wall
polysaccharides, which limits the bioavailability of ferulic acid from cereal
products to the merely form of free ferulic acid.
Processing possibilities in the development of cereal products might be used to
optimize the bioavailability of ferulic acid in humans and the possible health
effect of the wholegrain product.
An innovative processing in bread making has been developed. The processing
consisted of pretreatments of the bran with an enzymatic mixture and yeast
fermentation before its incorporation into the dough. The impact on the in
vitro assessed bioavailability of ferulic acid was a 5-fold increase over the
normal bran enriched wholegrain bread in a gastrointestinal model. Therefore in
our study we will compare the kinetics and total bioavailability of ferulic
acid from wholegrain breads enriched in native or pretreated bran. Furthermore,
the colonic metabolism of ferulic acid and overall major colonic metabolites
such as short chain fatty acids (SCFA) will be studied. Finally, total
antioxidant capacity and ex vivo inflammatory responses will be investigated in
order to determine the effect of the pretreatment of on the immunomodulatory
properties of bran.

The aim of the present study is to investigate the effect of pretreatment of
bran on improving the bioavailability of ferulic acid. As secondary endpoints
we will investigate the changes in plasmatic antioxidant capacity,
anti-inflammatory effects, colonic metabolites from ferulic acid and short
chain fatty acids (SCFA).

Blind, cross-over, randomised design. Wash-out period of one week. Three days
of low antioxidant diet. Standardised meal low in phenolic and antioxidant
compounds will be consumed the evening before the trial.

Intervention: Consumption of 300 g of wholegrain enriched with native or
pretreated bran.

Each volunteer will participate in the study on two separate occasions (each
test will take approximately 24 hours). Blood will be drawn at different time
points via a catheter (in total 156 ml per test-day) and a 24-hour urine sample
will be collected. Participants are asked to consume a standardised meal the
evening before each of the two test-days and the evening of the intervention
day. Volunteers are instructed not to consume any wholegrain or bran containing
products, nuts and seeds, antioxidant supplements or beverages high in phenolic
compounds or any phenolic rich food for 3 days before each of the three trials.
Subjects are asked to record their food intake for 3 days before each of the
trials. All the ingredients used in the bread baking are safe for human
consumption. The bread is consumed once at the beginning of the test. The
volunteers will not benefit from the study. The major risk of the study is the
amount of blood take from the volunteer and this risk is limited.