524 Chapter 20
feeding. Insoluble fi ber also tends to settle
during tube feeding, so soluble fi bers may be
better suited to these applications. Ultimately,
it is the careful blending and adjustment of
all of these factors which results in an accept-
able product.Sports/Performance Nutrition
For serious athletes, a high - protein diet (pref-
erably one that is also rich in branched - chain
amino acids, particularly leucine) is consid-
ered very desirable. Leucine is known to be
involved in priming skeletal muscle to
receive meal - derived nutrients, particularly
amino acids and sugars. A high - protein diet
can supply appropriate building blocks for
rapid muscular development and satisfy the
elevated maintenance requirements in high -
performance athletes.
In sports nutrition products, end user con-
cerns about overall rapidity of delivery of
nutrients, especially protein, and the muscle
impact of specifi c amino acids (branched -
chain amino acids) has led to a preference for
whey protein. Whey protein is rapidly
digested. It is highly soluble and does not
form a curd in the stomach, which allows
rapid stomach emptying. Furthermore, it is
somewhat higher in overall branched - chain
amino acid content than other typical nutri-
tionally acceptable proteins such as casein
and soy, though this content difference is not
profound.
The physiological situation is more
complex than is currently understood by the
typical consumer. It is theoretically possible
to overload the skeletal muscles ’ ability to
absorb amino acids, which results in their use
to produce energy or fat — both undesirable
outcomes for dietary protein. Sports nutri-
tional products also can be fortifi ed with
purifi ed free amino acids to achieve a variety
of end objectives, though this is somewhat
limited by objectionable fl avor and aroma
characteristics, at least in some cases such as
leucine and methionine. Based on digestionThe potential for product refl ux back to
the container is another packaging consider-
ation. This can substantially contaminate the
product with gut - associated microorganisms,
ultimately reducing the product use (or hang)
time; it may even potentially be dangerous to
the patient. Products intended for tube
feeding vary widely in caloric densities and
nutrient distribution, depending on the needs
of the patient. They must be stable in their
original container and also in the container
that is used during tube feeding (if that is
different).
Some products are thin bodied and need
enhanced viscosity to prevent phase separa-
tion. Viscosity can be increased by careful
selection of the protein system, use of multi-
valent cation minerals, and/or addition of
stabilizers. High concentrations of multiva-
lent cations or stabilizers can cause gelation
and unsightly phase separation. Appropriate
product viscosity is not just an issue of mouth
feel and pouring characteristics; it also can
seriously affect swallowing performance
(especially in patients with impairments
such as dysphagia, in which case thick prod-
ucts are desirable) as well as tube feeding
performance.
The necessity to deliver consistent nutri-
tion through a small diameter tube also places
restrictions on product viscosity, prevention
of phase separation during feeding, and the
absence of particulates (such as cream or
sediment chunks) in the fi nished product. A
number of actions can be taken to control
viscosity in tube feeding formulations, which
becomes more critical in high - caloric density
(and especially in high - protein content)
systems. Relatively low levels of hydrolysis
of the protein system or use of insoluble
mineral salts to deliver mineral requirements
instead of soluble salts can reduce viscosity
signifi cantly. Although insoluble salts (par-
ticularly of multivalent cations) help to
prevent increased viscosity, they also can
form sediment sheets during product storage
and may present diffi culties during tube