J. Clin. Biochem. Nutr., 42, 45–49, January 2008
JCBN Journal of Clinical Biochemistry and Nutrition0912-0009 1880-5086the Society for Free Radical Research Japan Kyoto, Japanjcbn2008007 10.3164/jcbn.2008007Original Article
Effect of Dietary Medium-Chain Triacylglycerol on Serum Albumin
and Nitrogen Balance in Malnourished Rats
Keiichi Kojima*, Akiko Ogawa, Reiko Nakamura, and Michio Kasai
Central Research Laboratory, The Nisshin OilliO Group, Ltd., 1 Shinmei-cho, Yokosuka, Kanagawa 239-0832,
1 1 2008 ?? ?? 200742 1 ?? ?? Received 4.6.2007; accepted 6.7.2007
*To whom correspondence should be addressed.
Tel: +81-46-837-2418Fax: +81-46-837-2466
Received 4 June, 2007; Accepted 6 July, 2007
Copyright © 2008 JCBN
Summary The present study was examined the therapeutic effect of medium-chain triacyl-
glycerol (MCT) in protein-energy malnutrition (PEM). Wistar rats were fed low protein diet
containing 70 g/kg of long-chain triacylglycerol (LCT) or MCT for 31 days. The serum
albumin concentration in rats fed MCT diet (2.88 ± 0.04 g/dl) were significantly higher
compared with those fed LCT diet (2.72 ± 0.04 g/dl) at day 31. Nitrogen balance was higher in
rats fed MCT diet (54.1 ± 2.3 mg/day) compared with those fed LCT diet (45.4 ± 2.4 mg/day)
during d 10–12. These results suggest that MCT effectively elevates serum albumin concentra-
tion and improves nitrogen balance in malnourished rats.
Key Words:rat, medium-chain triacylglycerol, protein-energy malnutrition, albumin
Many elderly people, especially those residing at nursing
homes or hospitals, tend to suffer from protein-energy
malnutrition (PEM) . For example, there is a high preva-
lence of malnutrition in a group of hospital outpatients
(30%) and groups of inpatients (up to 60%) in United
Kingdom , while up to 85% of older adults in nursing
homes are suffering from malnutrition in the United States
. PEM is defined as a serum albumin concentration of
less than 35 g/l . PEM in elderly people is associated
with impaired activity and general physical condition, a high
prevalence of infections, increased risk of developing
pressure sores, reduced mental capacity and increased
mortality rate . So, some measures should be taken
against this disorder.
Individual differences of calorie requirement in elderly
person are comparatively large and ability of digestion
and absorption decline with aging. So, uniform nutritional
supports are not necessarily effective. We thought that
changing nutritional support from quantitative to qualitive
might be effective.
Medium-chain triacylglycerol (MCT), composed of
medium-chain fatty acid (MCFA) such as octanoic and
decanoic acids, has several unique nutritional and physio-
logical properties. While long-chain fatty acid (LCFA) is
absorbed via the intestinal lymphatic ducts and transported
as chylomicrons to systemic circulation, MCFA is absorbed
via the portal system and rapidly transferred to liver, then is
MCT was first used in clinical nutrition in the 1950s for
dietary treatment of malabsorption syndromes caused by
rapid absorption . MCT was also used for rapid calorie
supply to postsurgical patients, who run into acute loss of
energy . The purpose of this study was to examine
whether administration of MCT is also effective to PEM,
which is caused by chronic loss of energy in elderly person,
using experimental animal model of PEM.
Materials and Methods
All animals were treated in accordance with the NIH
K. Kojima et al.
J. Clin. Biochem. Nutr.
Guide for the Care and Use of Laboratory Animals . This
experiment was performed after getting approval of in-house
animal experimental committee. Specific pathogen-free 3-
week-old male Wistar rats weighing 37–48 g were pur-
chased from Japan SLC (Shizuoka, Japan) and given a
standard commercial diet (Labo MR Stock, Nosan Corpora-
tion, Yokohama, Japan) for 3 days. They were housed indi-
vidually in stainless-steel mesh cages and allowed free
access to filtered tap water under controlled conditions
(temperature 22 ± 2°C, humidity 50 ± 10%, lights on from
0800 to 2000 h).
Following the acclimation period, the animals were
divided into 2 groups of 6–7 animals each and were allowed
free access to the semi-purified diets (Table 1) for 31
days. Food intake and body weight was recorded three
times a week. At the end of feeding period, the rats were
anesthetized with diethyl ether, and blood was collected by
decapitation. The serum was separated by centrifugation at
1900 × g for 5 min at 16°C. The lung, heart, liver, spleen,
kidney, intestine, testes, epididymal fat, paranephric fat,
mesenteric fat, gastrocnemius, plantaris, soleus and
diaphragm were removed and weighed. The visceral weight
was defined as the sum weight of lung, heart, liver, spleen,
kidney, intestine and testis. From each groups, 3–4 rats were
randomly selected, and feces and urine were collected
during two days from day 10 to day 12, stored at −20°C until
Experimental oils and Diets
Rapeseed oil as long-chain triacylglycerol (LCT) was
used as control oil. MCT was purchased from Nisshin
OilliO, Ltd (Tokyo, Japan) and used as test oil. Table 2
shows the fatty acids composition of the experimental oils.
Table 1 shows the composition of the experimental diets.
Each diet included 70 g/kg of the respective experimental
oil. They were prepared by modifying the AIN-93 diet .
The proportion of casein lessens from 20% to 5%. To adjust
the weight in diets detracted with casein, beta-starch was
Analysis of plasma
Serum concentration of total protein was measured by
Biuret method and albumin was measured by BCG method
(A/G B-Test Wako; Wako Pure Chemicals, Osaka, Japan).
Transferrin was estimated by TIA method (SRL, Tokyo,
Japan). Ketone bodies and free fatty acids were estimated
enzymatically (SRL, Tokyo, Japan). Urea nitrogen was
estimated using urease-UV method (SRL, Tokyo, Japan).
Amino acids were estimated by HPLC (SRL, Tokyo, Japan).
Analysis of N-balance
Collected feces were freeze-dried and powdered using a
commercially available small electric coffee mill. Nitrogen
concentration was determined using the Kjeldahl method
 in feeds, carcass, viscera, feces and urine. N balance
was calculated from dietary N intake (NI), fecal N excretion
(FN) and urinary N output (UN) using following equations:
N balance = NI – FN – UN
All results were expressed as the mean value ± standard
error (SE). Statistical significance of the difference among
values was analyzed by Student’s t-test.
Growth, body composition and body fat content
There were no differences in initial body weight, final
body weight, food intake and energy intake between the
LCT and MCT groups (Table 3).
Table 1.Composition of the experimental diets
1 Contains 0.02% (w/w) tert-Butylhydroquinone.
Beta-Corn Starch 547.5547.5
Lactic Casein 50.050.0
Alfa-Corn Starch132.0 132.0
Cellurose fiber50.0 50.0
Mineral mix (AIN-93G)35.035.0
Vitamine mix (AIN-93)10.010.0
Table 2. Fatty acid composition of the experimental oils
1 Number of carbon atoms: number of double bonds.
2 ND = not detected.
Fatty acidLCT MCT
(g/100 g total fatty acids)
C10:0 ND 25.6
Effect of MCT on PEM Rats
Vol. 42, No. 1, 2008
There also were no differences in visceral weight, visceral
fat weight (epididymal, paranephric and mesenteric fat),
lower extremity muscle weight (gastrocnemius, plantaris
and soleus) and diaphragm weight between the LCT and
MCT groups (data not shown).
There were no differences in plasma total protein concen-
tration between the LCT and MCT groups (Table 4).
However, plasma concentration of albumin and transferrin
were significantly higher in the MCT group than in the LCT
Plasma concentration of total amino acids, essential
amino acids, nonessential amino acids and glycogenic
amino acids were significantly lower in the MCT group
than in the LCT group (Table 5).
No difference was observed in the plasma free fatty acids
concentration between two groups. Serum total ketone
bodies and beta-hydroxybuthylic acid were 1.4 times higher
and acetoacetic acid was 1.7 times higher in the MCT group
though there was no significant difference (Table 6).
Nitrogen balance of d 10–12 was significantly higher in
the MCT group than in the LCT group (Table 7). Visceral
nitrogen content of d 10–12 was significantly higher in the
MCT group than in the LCT group. No significant difference
was observed in other parameter.
In this study, we examined whether MCT intake is effec-
tive in PEM, which is frequent chronic energy and protein
Table 3. Body weight and food intake of rats fed experimental
1 Values are means ± SEM.
(n = 6)(n = 7)
Initial body weight (g)58.3 ± 1.3 58.4 ± 1.3
Final body weight (g)123.3 ± 3.0 127.8 ± 3.5
Food intake (g/day)12.9 ± 0.3 13.2 ± 0.3
Energy intake (kcal/day)48.6 ± 1.149.5 ± 1.3
Table 5. Plasma amino acids and it’s metabolite of rats fed experimental diets1
1 Values are means ± SEM.
Significantly different from LCT group:*p<0.05,**p<0.01.
Total amino acids (nmol/ml)3705 ± 1453186 ± 114*
Essential amino acids (nmol/ml)1154 ± 32951 ± 39**
Nonessential amino acids (nmol/ml)2552 ± 117 2236 ± 81*
Essetial AA/Nonessential AA0.45 ± 0.010.43 ± 0.01
Branched chain amino acids (nmol/ml)326 ± 14304 ± 21
BCAA/Total amino acids0.088 ± 0.001 0.095 ± 0.004
Fisher ratio3.39 ± 0.12 3.30 ± 0.12
Glycogenic amino acids (nmol/ml)2385 ± 83 2047 ± 66**
Glycogenic AA/total AA0.28 ± 0.000.28 ± 0.01
Table 4.Plasma proteins of rats fed experimental diets1
1 Values are means ± SEM.
Significantly different from LCT group: *p<0.05, **p<0.01.
Albumin (g/dl) 2.72 ± 0.04 2.88 ± 0.04*
Total protein (g/dl)4.13 ± 0.074.27 ± 0.06
Transferrin (mg/dl) 137 ± 1143 ± 1**
Table 6. Plasma free fatty acids and ketone body fraction in rats fed experimental diets1
1 Values are means ± SEM.
Free fatty acids (µEq/l)706 ± 28 700 ± 55
Acetoacetic acid (µmol/l) 121 ± 35 206 ± 35
Beta-hydroxybuthylic acid (µmol/l)1662 ± 2502297 ± 211
Total ketone bodies (µmol/l) 1783 ± 269 2503 ± 235
K. Kojima et al.
J. Clin. Biochem. Nutr.
loss in elderly person.
Fed a low protein diet, serum albumin concentration in the
MCT group was significantly higher than in the LCT group,
suggesting that MCT intake has a preventive effect on PEM.
In addition, N-balance was higher in the MCT group than in
the LCT group and this may be a primarily cause of above-
mentioned preventive effect of MCT.
As nitrogen equilibrium of adult healthy subject is nearly
equal, their internal protein pool is constant. In some elderly
person however, nitrogen equilibrium is negative, because
of anorexia, deflection of palatability, lowering ability of
digestion and absorption accompanied by aging. In these
subjects, internal protein pool gradually decreases and
results in loss of body weight, decreasing mass of muscle or
visceral protein, lowering concentration of serum albumin.
Some of these are diagnosed with PEM.
The malnourished state has long been recognized as a po-
tential precipitating factor in the development of hypoalbu-
minemia . When serum albumin decreased by 1 g/l, the
odds of being classified as malnourished increased 1.1 times
. So, serum albumin is a marker of nutritional status .
In this study, serum albumin concentration was higher in the
MCT group than in the LCT group, suggesting that nutri-
tional status of the MCT group was improved.
Serum albumin has been the most common index of nutri-
tional status . But, Half-life of albumin is very long, and
its total body pool is by far the largest among the plasma
proteins . In addition, its serum concentration is
influenced by many factors independent of nutritional
factors such as infections  and trauma  (by an
increase in the transcapillary escape rate of albumin),
hydration status (by haemodilution), liver function (by a
decrease in synthesis) and kidney disease (by albumin
losses). Thus, the relevance of albumin as a nutritional
parameter has repeatedly been questioned . On the other
hand, half-lives of transferrin is relatively short. PEM is
characterized by serum transferrin concentration . In
the present study, Serum concentration of transferrin was
higher in the MCT group than in the LCT group, also
suggesting the improvement of nutritional status in the MCT
In case of fasting or glucoprivation, there is a flux of
alanine from muscle to liver to support hepatic gluconeo-
genesis , and amino acids derived from muscle protein
are also an important substrate for gluconeogenesis . So,
in such case, plasma pools of amino acids are increased .
In PEM, the concentrations of essential amino acids (EAA)
decrease, while those of nonessential amino acids (NEAA)
increase, and the EAA/NEAA ratio (E/N ratio) falls . In
our study, serum concentration of NEAA and glycogenic
amino acids was lower in the MCT group. It also supports
the above-mentioned speculation that the nutritional status
in the MCT group was improved.
Medium-chain fatty acids, generated by MCT hydrolysis,
are metabolized rapidly in mitochondria and yield a large
amount of acetyl-CoA, which are converted to ketone
bodies and are released to blood . So, continuous intake
of MCT, compared with LCT, results in increased concentra-
tions of blood ketone bodies . Ketone bodies are
produced in the liver, mainly from the oxidation of fatty
acids, and are exported to peripheral tissues for use as an
energy source  when glucose is not readily available.
Ketone bodies are always present in the blood and there
levels increase during fasting . During fasting, ketone
bodies tend to suppress gluconeogenesis and protect the
protein stores . In this study, serum concentrations of
total ketone bodies were higher in the MCT group than in the
LCT group by about 40%. Maybe these increased ketone
bodies were act as alternative fuel and suppress protein
Nitrogen excretion was suppressed in premature infants
fed MCT-containing formula . In burned rat receiving
the chemically structured triacylglycerol with MCT and
LCT, protein energy expenditure was decreased while whole
energy expenditure remained stable . It suggests that
probably non-protein energy expenditure was increased due
to rapid oxidation of MCT, and protein utilization was
spared. As a result, nitrogen balance was higher in the rat
receiving structured lipid. Moreover, serum albumin
concentration was higher in the structured lipid receiving rat
. In our study, nitrogen balance in the MCT group was
higher during the day 10–12, and serum albumin concentra-
tion of this group was also higher at d 31. Judging from these
observations, increasing concentration of serum albumin
resulting from administration of MCT might be due to in-
creased nitrogen balance of these animals.
In this study, we test the possibility of exploitation of
MCT in prevention or curing of PEM, and showed that MCT
administration might has the improvement effect of hypo-
albuminemia and low nitrogen balance, which are typical
and diagnostic symptom of PEM.
Table 7. Nitrogen balance in rats fed experimental diets1
1 Values are means ± SEM.
Significantly different from LCT group:*p<0.05.
Nitrogen intake71.8 ± 4.2 83.5 ± 2.6
Fecal nitrogen 11.3 ± 1.9 13.9 ± 0.7
Urinary nitrogen 14.9 ± 2.315.8 ± 1.6
Nitrogen balance45.4 ± 2.454.1 ± 2.3*
Carcass nitrogen 2847 ± 1242925 ± 112
Visceral nitrogen336 ± 13 369 ± 5*
Effect of MCT on PEM Rats
Vol. 42, No. 1, 2008
EAA, essential fatty acid; FN, fecal nitrogen; LCFA,
long-chain fatty acid; LCT, long-chain triacylglycerol;
MCFA, medium-chain fatty acid; MCT, medium-chain
triacylglycerol; NEAA, non-essential fatty acid; NI,
nitrogen intake; PEM, protein-energy malnutrition; UN,
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