EFFECT OF TWO DIETARY SOLUBLE FIBERS ON CHOLESTEROL AND TRIGLYCERIDE CONCENTRATIONS IN HUMAN PLASMA J. Robert Cade, R. Malcolm Privette, Virginia B. Zele and Melvin J. Fregly
ABSTRACT: As elevation of concentrations of serum cholesterol, particularly the LDL fraction, and of serum triglyceride has been shown to correlate with development of coronary artery atherosclerosis while reduction of these lipid moieties retards or reverses atherogenesis. It is important to find approaches which favorably alter serum lipids without undesirable side effects. We have studied two soluble fibers, which
Departments of Medicine and Physiology, College of Medicine,
can be administered in a palatable drink, to ascertain their effect on cholesterol and triglycerides in 14 men and 10 women, who were found during a four week period to have consistently elevated cholesterol and
University of Florida, Gainesville,
triglyceride concentrations. After the control period, the subjects were
FL 32610-0204
divided into three groups. One group was given a placebo (P) which contained citric acid and orange flavor and was sweetened with 1/4 g
Running Title: Dietary Fibers on
Aspertame and 5 g sucrose per 8 oz.; the second group received the
Cholesterol and Triglyceride
same drink to which 6 g Gum Arabic {GA) /8 oz was added; the third the same drink to which 4 g carboxymethylcellulose (CMC) was added. Each subject ingested 8 oz of drink TIO ac and at bedtime for eight weeks, during which total cholesterol, HDLC, LDLC and triglycerides were measured at weekly intervals. All patients were then changed from their original test drink to one of the other drinks for eight weeks and then crossed over again to the third drink so that during the course
Send Correspondence to:
of the study all subjects received GA 24 g/day, CMC l6 g/day, and
J. Robert Cade, M.D.
placebo for eight weeks. Eight subjects then ingested the drink with
Departments of Medicine and
GA 4 g/8 oz for an additional eight weeks. There were no changes in
Physiology Box 100204, JHMHC University of Florida
TC, HDLC, LDLC, the ratio HDLC/LDLC, or triglycerides during placebo administration. During GA 6 g/8 oz TC fell 17.9% (p<0.01), LDLC 21.4% (p<0.001), HDLC increased 12.9% (p<0.06), the ratio HDLC/LDLC increased 44% (p<O. 001} while triglycerides decreased 50%. When
Gainesville, FL 32610-0204
GA 4 g/8 oz was tested TC decreased 5.6% {p<0.05), LDLC and HDLC
Tel: (904) 392-8952
did not change, nor did the ratio HDLC/LDLC. Triglycerides, however,
Fax: (904) 392-8481
decreased 42.7% (p<0.05). When CMC was given TC decreased Continued on next page
8.8% (p<0.05) and LDLC 9.7% (p<0.05), HDLC/ LDLC increased 10.4% (p<0.05) while triglycerides did not change. Our data show GA is a potentially useful agent for preventing and for treating coronary atherosclerosis.
: s d r o w y e K
Soluble Fibers, Gum Arabic, Carboxymethylcellulose, Cholesterol
Elevations in the concentrations of cholesterol (Frick, 1987; Lipid Research Clinics Program,
in hyperlipidemic patients. One of these fibers,
1984) and triglycerides (Aberg, 1985; Carlson and
Gum Arabic (GA), is a highly soluble complex acidic
Battiger, 1985) in plasma have been implicated in
heteropolysaccharide of high molecular weight
the development of atherosclerosis in humans. Both
composed of a branched array of galactose, arabinose,
experimental observations in laboratory animals
rhamnose, and gluevronic acid (Anderson, 1966). It
(Baekey, 1988) and epidemiologic studies in humans
has been used for many years in the manufacture
(Carlson, 1985) indicate that elevation of low density
of confections and soft drinks. The second fiber,
lipoprotein (LDL) cholesterol hastens, while high
carboxymethylcellulose (CMC), is synthetically
density lipoprotein (HDL) cholesterol either retards
derived. It has been used as a suspending aid for some
or reverses atherogenesis.
insoluble pharmaceutical compounds.
Ingestion of several soluble fibers in the diet has
The objective of the present studies was to determine
been shown to lower LDL cholesterol (Anderson,
the effect of chronic ingestion of GA and CMC on
1984; Cerda, 1988). We, therefore, elected to study
the various cholesterol fractions and on triglyceride
the effect of two previously untested soluble fibers
concentrations in a group of patients with hypercho-
on serum cholesterol and triglyceride concentrations
lesterolemia and elevated triglyceride concentration.
SUBJECTS AND METHODS: Twenty-four subjects, 14 men and 10 women,
on an identical fluid to which 6 g GA/8 oz was added,
between the ages of 38 and 65 years who had type
and 8 were started on the same fluid to which 4 g
IIb hyperlipoproteinemia were enrolled in the study
CMC/8 oz was added. The concentration of CMC was
following, four weeks of blood testing to assure that
limited as higher concentrations caused the drink to
they, indeed, had elevated serum cholesterol and
become so viscid it was not palatable. All subjects
triglyceride concentrations. The purpose of the study
were instructed to consume 8 oz of their test drink
and the methods to be used were explained to each
four times each day. After 8 weeks, those subjects on
subject and informed consent was obtained.
the placebo drink were randomly assigned to either GA or CMC while those who had been ingesting one
After base-line information was obtained over a
of the fiber drinks were followed for 4 additional
4 to 6 week period, 8 subjects were started on an
weeks before being reassigned to either placebo or
orange flavored placebo drink sweetened with 1/4 g
the other fiber drink. The same procedure was again
Aspartame and 5 g sucrose per 8 oz; 8 were started
followed after the l6th week so that over the course Continued on next page
2
of the study each subject had 3 four week control
count, measurement of total cholesterol, HDL and
periods and was exposed to each drink for 8 weeks.
triglycerides (using Sigma Diagnostic Kits No. 351
After the 24th week of treatment 8 subjects agreed to
& 356), VLDLC was calculated by VLDLC = TG x .2
extend the study 8 weeks by taking the drink to which
and LDLC = TG - {VLDLC•HDLC); Glucose, alkaline
4 g GA/8 oz had been added.
phosphatase, SGOT, SGPT, total and direct bilirubin, and creatinekinase and lactic dehydrogenase which
Subjects were instructed not to alter their diet in
were measured by previously reported methods
any way throughout the study and body weight was
(Cade, 1992). A physical exam was done at each visit
measured weekly to monitor, as well as possible,
and an EKG was obtained at the first visit and at the
adherence to this request.
end of each 8 week experimental period.
Blood was obtained, in the fasting state, at
Results were evaluated statistically by analysis of
weekly intervals during the study. The following
covariance for multiple observations (Winer, 1971).
determinations were made: a complete blood
RESULTS: Figure 1 shows the total cholesterol,
Fig. 1
HDL cholesterol, LDL cholesterol and
Mean weekly total cholesterol, LDL cholesterol, HDL cholesterol and ratio HDL:LDL cholesterol during a 4 week control period and during an 8 week period of placebo ingestion.
lhe ratio HDL/LDL cholesterol during
PLACEBO
the control period preceding and during the 8 weeks of placebo ingestion.
HDL
Total Cholesterol
Mean total cholesterol during the control
8.0
1.6
HDL concentration was 1.51 mmol • l-1 during the control period and did not
m mol • l -1
change with placebo ingestion. The
m mol • l -1
period was 7. 2 mmol • l-1 and did not
change with treatment; likewise, the
1.0
6.5
LDL cholesterol which was 4.4 mmol
-4 -2 0 2 4 6 8
-4 -2 0 2 4 6 8
• l and the HDL/LDL ratio which was
Weeks
.317 during the control period did not
LDL
-1
change significantly during placebo
Weeks
HDL/LDL
5.2
1.0 m mol • l -1
m mol • l -1
consumption.
4.7
4.2
-4 -2 0 2 4 6 8
Continued on next page
1.3
Weeks
0.8 0.6 0.4 0.2 0.0
-4 -2 0 2 4 6 8 Weeks 3
Fig. 2
Total Cholesterol
HDL
7.0
1.6 m mol • l -1
Figure 2 shows the same information
GUM ARABIC (16g / day)
m mol • l -1
Mean weekly values for total cholesterol, its LDL and HDL fractions and the HDL:LDL ratio during a 4 week control period and an 8 week experimental period during which 16g Gum Arabic was ingested each day.
6.5
5.2
during the trial in which 24 g GA/day was
1.0
-4 -2 0 2 4 6 8
ingested. Mean total cholesterol during
1.3
-4 -2 0 2 4 6 8
Weeks
Weeks
the control period was 7. 97 mmol • l
-1
LDL
and fell progressively during the trial to
HDL cholesterol increased from 1. 4 to 1. 58 mmol • l-1 (p<O. 06) , LDL cholesterol
m mol • l -1
During ingestion of 24 g GA each day,
1.0
m mol • l -1
6. 55 mmol • l-1. This decrease of 17. 6% was statistically significant with a p<0.01.
HDL/LDL
4.2
3.6
decreased from 5. 3 5 to 4. 21 mmol • l (p<O. 04), and the ratio HDL/LDL
0.6 0.4 0.2 0.0
-4 -2 0 2 4 6 8
-1
0.8
-4 -2 0 2 4 6 8
Weeks
Weeks
increased from .262 to .379 (p<0.001).
Fig. 3
GUM ARABIC (24g / day) Total Cholesterol
HDL
1.7 m mol • l -1
8.0 m mol • l -1
Mean weekly, values for total cholesterol, its LDL and HDL fractions and the HDL:LDL ratio during a 4 week control period and an 8 week experimental period during which 24g Gum Arabic was ingested each day.
7.5 7.0 6.5 6.0
-4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9
Weeks
1.6 1.5 1.4 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9
Weeks
Figure 3 shows the data obtained during ingestion of 16 g GA/day. Total
6.5
LDL
0.6
HDL/LDL
mmol • l-1 (p<0.05); HDL cholesterol increased from 1. 27 to 1. 4 mmol • l-1 (p<O.08); LDL cholesterol did not change significantly while the ratio HDL/LDL increased from .337 to .360 (p<0.06).
m mol • l -1
cholesterol fell from 6.86 to 6.49 0.4 5.2 0.2 4.0
-4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9
Weeks
0.0
-4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9
Weeks
Continued on next page
4
Fig. 4
Mean body weight decreased slightly more than 0.5 kg during the 8 weeks of treatment with 24 g GA/day and did not change in the other 3 treatment regimens. There were no changes in EKG throughout the study; likewise, liver function studies, muscle enzymes, glomerular filtration rate, urinalysis, and hematologic parameters did not change.
HDL
m mol • l -1
m mol • l -1
1.6
7.8
6.5
1.3
1.0
-4 -2 0 2 4 6 8
-4 -2 0 2 4 6 8
Weeks
Weeks
LDL
HDL/LDL
6.5
1.0 m mol • l -1
Figure 5 shows the changes in serum triglyceride concentration which occurred during both control and treatment periods with the four test fluids. There were no significant differences in triglyceride concentration comparing control to treatment periods in either the CMC or placebo ingestion trials. When GA was the test substance, however, a significant decrease occurred when both the 16 and 24 g/day doses were administered. The decline during treatment with 24 g/day (from 2.67 to 1.28 mmol • l-1) was statistically significant (p<O. 001). During treatment with 16 g/day, the decline from 3.91 to 2.74 mmol • l-1 was also statistically significant (p<0.05).
Total Cholesterol 9.0
m mol • l -1
Figure 4 shows the values obtained during CMC trials. Total cholesterol declined from 7. 64 to 6. 96 mmol • l-1; this 8Wmol • l-1 (p<0.05): while the HDL increased from 1.34 to 1.48 mmol • l-1 (p<0.07). The ratio HDL to LDL increased from .269 to .297 (p<O. 05).
CARBOXMETHYLCELLULOSE (16g / day)
5.2
4.0
-4 -2 0 2 4 6 8
0.8 0.6 0.4 0.2 0.0
-4 -2 0 2 4 6 8 Weeks
Weeks
Fig. 5
Mean weekly values for serum triglycerides during a 4 week control period and an 8 week experimental period during which either a placebo, Gum Arabic 16g (o) or 24g/day, or CMC 16g/day was ingested.
SERUM TRIGLYCERIDE CHANGES DURING SOLUBLE FIBER ADMINISTRATION Placebo Gum Arabic (16g / day) Gum Arabic (24g / day) Carboxymethyicellulose (16g / day)
4.6
m mol • l -1
Mean weekly values for total cholesterol, its LDL and HDL fractions and the HDL:LDL ratio during a control and an experimental period during which 16g carboxymethylcellulose was ingested each day.
3.6 2.6 1.6 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9
Weeks
Continued on next page
5
Almost all subjects noted increased flatulance and increase in bulk and frequency of stools during both GA and CMC ingestion. One subject had frequent abdominal cramping during ingestion of 24 g GA/ day but did not have to discontinue therapy.
DISCUSSION: Elevation of the concentrations of cholesterol and
is surprising as a metabolic effect in the internal
triglyceride in serum has been shown to be of
milieu would be required for such a result and it
importance in the genesis of atherosclerotic vascular
has not been shown that GA is absorbed from the
disease (Aberg, 1985; Baekey, 1988; Carlson, 1985;
intestine.
Frick, 1987; LRCP, 1984). Hence, the search for agents which will lower the concentration of these
The marked effect of both doses ot GA on
substances in plasma is of therapeutic importance.
triglyceride concentration is consistent with binding
Useful agents must be, first, easy to ingest, and
of triglyceride in the intestinal lumen. There was a
secondly, they must be free of untoward side effects.
mean weight loss of approximately 0.5 mg during the 8 weeks the subjects ingested 24 g GA/day.
The present studies show that both GA and CMC
While this was not statistically significant, it suggests
lowered total and LDL cholesterol significantly. In
that a longer trial may be necessary to determine
addition, HDL cholesterol increased significantly
whether the absorption of triglyceride in the small
during the ingestion of GA. The mechanism by
intestine, and its removal to the large intestine
which GA and CMC lower cholesterol is unknown.
where it undergoes bacterial degradation, is of great
Some investigators (Anderson, 1979) have assumed
enough magnitude to play a role in weight loss.
that absorption of bile acids in the intestine with excretion in the stool is the biologic mechanism
It should be noted that the 18% decrease in total
by which soluble fibers lower cholesterol. Ross,
cholesterol during high dose GA trials, the 5.3%
(1983), however, found that neutral sterols and bile
during low dose, and the 5.9% decrease with CMC
acids in the stool of humans did not increase when
occurred with no dietary change in ingestion of
GA was given. Thus, although pectin (Ross, 1983)
either fat or calories. If a low fat diet were combined
and bean and oat diets (Anderson, 1984) which
with fiber ingestion, it is possible that a greater
increase bile acids and neutral sterol excretion may
reduction in both the concentrations of cholesterol
lower cholesterol through this mechanism, it seems
and triglyceride would have occurred and that much
apparent that the hypocholesterolemic effect of GA
greater weight loss with its salubrious effect on
must be accomplished through some other pathway.
plasma concentration of cholesterol and triglyceride
The rise in HDL cholesterol during GA consumption
may also result.
6
REFERENCES: Aberg, H., Lithell, I., and Hedstrand, H. 1985. Serum triglycerides are a risk factor for myocardial infarction but not for anginapectoris: results from a 10 year follow-up of Uppsala Primary Prevention Study. Atherosclerosis 54:89-97. Anderson, D.M.W., Hirst, E., and Stocidard, J.F. 1966. Some structural features of acacia senegal (gum arabic). J. Chem. Soc. (Sect. C), 1959-1966. Anderson, J.W., and Chen, W.J.L. 1979. Plant fiber: carbohydrate and lipid metabolism. Am. J. Clin. Nutr. 32: 346-363. Anderson, J.W., Story, L., Sieling, B., Chen, W.J.L., Petro, M.S., and Story, J. 1984. Hypocholesterolemic effects of oat-bran or bean intake for hypercholesterolemic men. Am. J. Clin. Nutr. 40: 1146-1155. Baekey, P.A., Cerda J.J., Burgin, C.W., Robbins, F.L., Rice, R.W., and Baumgartner, T.G. 1988. Grapefruit pectin inhibits hypercholesterolemia and atherosclerosis in miniature swine. Clin. Card. 11:595-600. Cade, R., Packer, D., Zauner, c., Kaufmann, O., Peterson, J., Mars, D., Privette, M., Hommen, N., Fregly, M.J., and Rogers, J. 1992. Marathon Running: Physiologic and chemical changes accompanying late-race functional deterioration. Eur. J. Appl. Physiol. 65:485-491. Carlson, L.A., and Battiger, L.E. 1985. Risk factors for ischemic heart disease in men and women; results of the 19th year follow-up of the Stockholm Prospective study. Acta Med. Scand. 218:207-211. Cerda, J.J., Robbins, F.L., Burgin, c.w., Baumgartner, T.G., and Rice, R.W. 1988. The effects of grapefruit pectin on patients at risk for coronary heart disease without altering diet on life style.. Clin. Card. 11: 589-594. Eurard, E., and Janssen, G. 1968. Gas-liquid chromatographic determination of human fecal bile acids. J. Lipid Res. 9: 226-236. Frick, M.H., Elo, O., Haapa, K., Heinonen, O.P., Heinsalmi, P., Helo, P., Hultunen, J.K., Kaitaniemi, P., Koskinen, P., Manvinen, v. , Maenpaa, H., Malkonen, M., Manttari, M., Norola, s., Pasternack, A., Pikkarainen, J., Ramo, M., Sjoblom, T., and Nikkila, E.A. 1987. Helsinki Heart Study: Primary-Prevention Trial with Gemfibrozil in Middle-Aged Men with Dyslipemia. NEJM 317: 1237-1245. Lipid Research Clinics Program: 1984. The lipid research clinics coronary primary prevention trial results. JAMA 251: 351-364. Ross, A.H.M., Eastwood,¡ M.A., Brydon, W.G., Anderson, J .R., and Anderson, D.M.W. 1983. A study on the effects of dietary gum arabic humans. Am. J. Clin. Nutr. 37: 368-375. Winer, B. J. 1971. Statistical principles in experimental design. McGraw-Hill, New York, pp. 514-608.
7