Nutricion en el deporte

Intermediary
Peter
ABSTRACT

metabolism

of fructose3

A Mayes
Most of the metabolic effects of fructose arc terious, phos- sylation

eg,

hyperlipidemia, lactacidemia, concentrates concerning Other

hyperuricemia, and on aspects

nonenzymic disturbances the general referred
augmented

fructomeof lipid subjects
secretion

due

to its rapid

utilization regulatory toinclude production,

by the step

liver in

and

it by-passing leading lipid and

the

phofructokinase reaching These ruvate genase, nonesterified low-density-lipoprotein long-term tions that triglyceridemia,
nemia. tion ished of Acute inorganic ATP synthesis.

glycolysis,

to

far tabolism. fructose,

of proteins, The paper particularly

in copper metabolism to are
insulinconsequences consequences and lactate and a shift fatty

carbohydrate immediate activation from These

metabolism.

its impact

on carbohydrate, the

hepatic increases of pyruvate secretion are

in balance acids, resulting (VLDL).

oxidation in increased effects

in pyand punine metabolism. dehydro- of other reviews in this to esterification of Of further consideration of very- isresponsible for some augmented

volume.
is whether

of the

metabolic
feeding whereas

effects
does sucrose

of fructose
not directly feeding

intake.
cause does (2).

by Compared with glucose, fructose absorption of fructose, which causes enzyme adapta- an increase in plasma insulin (1) increase lipogenesis and VLDL secretion, leading to Thus whenever intake of fructosedecreased glucose tolerance, and hyperinsuliadded effect of insulin secretion
loading of phosphate Consequently, the liver in with fructose causes and by Al? sequestradiminof the only is this the case with sucrose fructose-l-phosphate the inhibition

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is accompanied must be taken
itself but
-

by glucose, into account.
HFSs are

the Notequiv-

some

alent and

to hydrolyzed (3). contain

sucrose Similar both

because considerations fructose and

they

are50%

glucose
to supplements

and
for

enzymes
acid

of are

adenine
accelerates

nucleotide
with

degradation
consequent

is removed
hyperuricemia. These

50% fructose uricathletes that

apply glucose.

formation

effects

ofparticular

significance
individuals.

to

potentially

hypertrigly-

ceridemic

or

hyperuricemic

Am

J

Clin

Nutr

General
Utilization

metabolism
of blood
consequence

1993;58(suppl):754S-765S.

fructose
of the

and
digestion

uptake
of

into
sucrose

tissues
and other fructose-

KEY
olism,

WORDS

Fructose,

intermediary

metabolism,sucrose,

The

immediate
lipid

effects,
metabolism,

long-term

effects,
enzyme

liver,
adaptation,

carbohydrate
lipogenesis,

metabacids,

containing

foods
and hepatic the liver

such
transport portal

as
vein.

honey,
of fructose Therefore, Because

fruits,
by all of

and
the

some
intestinal

vegetables,
epithelium absorbed of an flows active

islow-density

lipoproteins,

insulin,

nonesterified

fatty

absorption veryinto the

hy-

fructose presence

pertriglyceridemia,

hyperuricemia

through

initially.

the

hepatic

enzyme

system

for

metabolizing

fructose, a fractional presented

fructose

readily after

Introduction
Virtually due
entry ose

passes into the liver, and 71%,respectively, all
the

accounting for of the fructose

uptake 55% of to the liver

the

unique factors:
of after

metabolic its
glycolysis bypassing

properties uptake
or the

to two
to phosphate

primary
pathway level

rapid

by

tube feeding fed or starved rats (4). In humans it was shown that of fructose are the liver metabolized at least half of the fructose injected...