HEALTH AND NUTRITION NEWSNo. 16
June 15, 2006

Table of Contents
Prefatory Note
Ten years’ partnerships between the NIHN and “Hana no kai” …………...………………Satoko Takeuji

CURRENT RESEARCH PROJECTS
Project for the Dietary Reference Intakes…………..…………..……………………….…..Satoshi Sasaki

THOUGHTS ON HEALTH AND NUTRITION RESEARCH
Health Promotion through nutritional supports for exercise and resting ……….…........ Yashuhiro Fujii

RESEARCH FINDINGS
Gly395Arg polymorphism of PPARα gene was not detected in Japanese population of 729 individuals..………………..Yasutomi Kamei
New quantitative index for dietary diversity (QUANTIDD) and its annual changes in Japan.…….…..Yasuhiro Matsumura
Effects of isoflavone and exercise on BMD and fat mass in postmenopausal women: A randomized
placebo-controlled trial………....…………………………………………………………..…Yoshiko Ishimi
A new attraction of sea food: Taurine deficiency creates a vicious cycle promoting……..………………...……Nobuyo Tsuboyama-Kasaoka© National Institute of Health and Nutrition

Prefatory Note

Ten years’ partnership between the NIHN and “Hana no kai”
Satoko Takeuji (maiden name: Tanaka)
Representative, Hana no kai
Bronze medalist in 100m backstroke at ROME 1960 Olympic Gamesbecause everybody could learn to swim well if
one receives the proper guidance, and improve
his/her physical strength. In addition, it is also
explored that swimming is effective to prevent
osteoporosis, which is a big concern among the
middle-aged and older women nowadays.
So far, it has been regarded that the sports that
accompany jumping and bouncing (e.g. tennis,
badminton) should be most effective to prevent
osteoporosis, which prevailed as a common
knowledge in the field of the Sport Medicine.
However, when we investigated the association
between bone density and swimming, we foundthat bone density of femur, at the neck of the legs,
was significantly higher among those withswimming history for two years, compared to thatof those who never have exercise habit. This was
also a quite surprising finding, defying ourcommon understanding. In this way, I can say thatthe data of the measurements at Hana no Kai
could give us a great asset”.
Lastly, Dr. Izumi Tabata (Program Director for
Health Promotion and Exercise, NIHN) said,
recalling the ten years’ activities, “The NIHN
moved in the current place in September 1992.
New building was equipped with a long-awaitedheated swimming pool and an exercise floor, so
as to facilitate the studies to examine the impact
of exercise in a certain group. While we repeateddiscussions to establish our research objectives,
Prof. Mitsumasa Miyashita (University of Tokyo atthat time) informed us that the members of the 7th“IBM woman’s seminar” launched a swimming
project and were looking for an available pool.
After the discussion with the members, ourresearch objectives agreed each other, and that ajoint project was established with Hana no kai”.
We, Hana no kai, are very grateful to the NIHN
for being the strong partner with providing us theplace for our activities, and that we would like tocooperate with undertaking our joint researches.

In January 1995, a swimming project “Researchon maintenance/promotion of health and physicalstrength in the working middle-aged and older
women” was launched by the National Institute of
Health and Nutrition (NIHN) in collaboration with
“Hana no kai (=a florescent group)”. On theoccasion of 10th anniversary, there was a seminarat the NIHN. Here, I would like to introduce theoutcome of ten years’ partnership between the
NIHN and Hana no kai, which was presented in
the above seminar.
First, Dr. Heizo Tanaka (then Director-General)
addressed that “I am very happy that this project
has been producing steadily good results, basedon scientific evidences. We would like to continue
our efforts to disseminate this valuable know-how
across the country, by which we expect to support
the middle-aged and older persons who continue
regular exercise”.
Next, Dr. Keiji Tanaka (then Director, HealthService Bureau, the Ministry of Health, Labourand Welfare) stated that “I am pleased that thisproject makes a great achievement. The Ministryof Health, Labour and Welfare launched “HealthJapan 21 (2000-2010)”. When we makesuggestions on various exercises as a part of theabove ten years plan, we would like to utilize theresults of this project as a guideline of exercise”
Prof. Mitsuru Higuchi (Faculty of Sport Sciences,
Waseda University) explained that “I have been
involved in this research since the foundation ofHana no kai, and we can see that there arevarious achievements by them. First, unlike
walking and jogging, for the persons who can not
swim, there is no physical change during the firstyear after s/he start swimming. And, physicalendurance would increase from the second year,
followed by further increase up to the forth year.
Consequently, one’s physical strength would also
increase. The above finding shows that it isimportant to create the first cue to start swimming,* The original Japanese version was translated by
Project for International Research and Development,2Current Research Projects
Project for the Dietary Reference Intakes
Satoshi Sasaki
Project for Dietary Reference Intakes
Nutritional Epidemiology Program
Do you know what “Dietary Reference Intakes

DRIs is revised and issued every five years.

(DRIs)” is? DRIs determines the amounts of

The latest version of DRIs will be used until theenergy (calorie) and 34 nutrients that Japanese

fiscal year 2009. We have started preparing thepeople should take, which was established by therevised one, which will be used from the fiscal

Ministry of Health, Labour and Welfare. DRIs isyear 2010.

used as a standard for the food services at school

Our duty is not only to collect the researches

and hospital, as basic information for dietary

undertaken in other institutes and universities,

guidance at health centers and hospitals, and as

and we also work on our own researches actively.

a basis for nutritional labeling of foods on market

In particular, our focus is “nutritional epidemiology

sale. In this way, DRIs is widely used for our

researches”,

healthy lives. The latest version “DRIs for

associations between nutrient/food intake andJapanese, 2005” was published in April last year.

health status of Japanese people. Eating habits

DRIs used to be called “recommended dietaryareallowance,” but it was renamed in line with theWesterners. Consequently, the disease structuredevelopment of nutritional science, transition ofis also different. For the formulation of ”DRIs fordisease structure, and trends in other countries.

Japanese,”

DRIs

carefuloverseas only can not be enough evidences, andconsideration of current nutritional and healththus the ones targeting Japanese people areproblems in Japan, by reviewing the researchrequired. Although the nutritional epidemiology isoutcomes of the scientist in Japan as well as inrelatively behind compared to other fields ofother countries. For which, we have to keep annutritional science in Japan, it is actually veryeye on nutritional researches undertaken all overimportant research field which would support

the world, collect all the information, examine

health of Japanese people. The mission of ourthem with experts’ eyes, evaluate them withproject is quite significant, and thus we feel aappropriate criteria, and then finally compile theheavy responsibility. We will appreciate yournecessary information. We, Project for the Dietarycontinuous support for our project.

isformulated,

with

the

Reference Intakes, have been playing a core rolein this process. In other words, our project aims to
make “a measure to support health of Japanesepeople from the nutrition point of view.” However,
our project alone is not working on all these tasks
and we work with the experts of our institute andthose of other institutes. In this process, we play
the role as a coordinator. About 100 scientists
were involved in the formulation of “DRIs forJapanese, 2005,” and in total over 50,000 articles
and technical documents were collected from allover the world for systematic review.
3

very

where

differentthewebetweeninvestigate

Japanese

researches

conducted

the

and

in

Thoughts on Health and Nutrition Research
Health promotion through nutritional supports for exercise and resting
Project Leader, Yasuhiro Fujii
Project for Nutraceutical ResearchCenter for Collaboration and PartnershipA long and healthy life seems to be an eternal
theme for human beings from ancient times.
There is a famous story that, around Jomon or
Yayoi Period in Japan, the First Emperor of theState of Qin (Qin Shi Huang: 始皇帝) in China
dispatched Xu Fu ( 徐 福 ) together with 3,000
young men and women to Hourai, a country
located in the east (according to one theory, thiscountry means Japan), in search for the elixir ofimmortality. There are many legends about Xu Futhat may or may not be true, all over Japan. You
may not have so strong desire for Immortality as
Qin Shi Huang had, but everyone must have awish for maintaining and promoting one’s health.
It is also not only Qin Shi Huang who would even
expect to maintain and promote one’s healthwithout a great effort. Resent fitness boom can bea good example; people would promptly jump at
the foods which are believed effective to lose
weight, make the skin younger and treat diseases.
When these foods did not work, and if they find
new health information, they would try other new
foods again, expecting that “It should work for thistime!” In this way, many people repeat the same,
without realizing that it was false information,
which may reflect the people’s wish to attain good
health without a great effort.
It is widely understood that nutrition, exercise
and resting are the important factors for healthmaintenance and promotion. It must be noted
however that people can be healthy and active,
only if the above factors could exert the effects
each other in a complementary way. In otherwords, solving the health problems by a separate
approach of nutrition, exercise, or resting would
make it impossible to reach the final goal of healthmaintenance and promotion. Let me give you an
example of exercise, which requires the biggest
effort among those three factors. While 64% ofJapanese reported that they were aware of beinglack of exercise (Health and Welfare Trend
Survey, 2002), ‘Walk count’ keep decreasing,compared to 5 years ago (National Health andNutrition Survey, 2002). These data show thatmany people recognize the need of more
exercise for their health, but end up taking noaction. We can not expect the behavioral change
in these people just by suggesting “Practice more
exercises for your health!”. Then, how aboutproviding the nutritional support, as a help forincreasing the amount of exercises or physicalactivities for health promotion? For example,
usually thirty minutes’ exercise is required to haveits effect, though what if the time required to havethe same effects can be shortened to 15 minutesby taking some kind of nutrients during exercise?
Or what if the subsequent fatigue can be reducedby taking some kind of nutrients during exercise,so that one could feel the exercise enjoyable?
I suppose that more people would be willing tostart exercise, if we could propose an easier way.
In our project, therefore, we work on the
researches to look into the nutrients and foods
which could enhance the effects of exercise. If we
could find evidences on such effects, we could
also support the implementation of “Exercise andPhysical Activity Reference Quantity (EPARQ) for
Health Promotion 2005” which was introduced in
the last issue (No. 15) by Dr. Izumi Tabata(Director of Health Promotion and Exercise
Program)” from the field of practical nutrition.
Fatigue during exercise would have links toresting. Considering that mental health problems
could be possibly affected by nutrients too, there
may be a possibility to support resting from thefield of nutrition.
As a specialist in the field of nutrition, I would
keep working on realization of these hypotheses.
4Latest Research
Gly395Arg polymorphism of PPARα gene was not detected in Japanese
population of 729 individuals.
Yasutomi Kamei (Nutritional Sciences Program)
All human beings belong to the species, Homo Sapiens, but there is variation from one person to another,such as in looks. Our genomic DNA sequences also differ from person to person. This difference in genomic
DNA between individuals is called a polymorphism.
Elucidation of the role of each polymorphism of our genes could be useful for determining the susceptibility ofeach individual to certain diseases. A person, with high-risk DNA polymorphism(s) to certain disease(s),should take precautions to reduce other non-genetic risk factors, including lifestyle. DNA polymorphism isconsidered to be associated, in particular, with lifestyle-related diseases such as diabetes, hypertension andobesity. In the case of classical genetic diseases, which are caused by a mutation of a single gene, onset of
disease can be predicted according to Mendel’s law. Obviously, lifestyle-related diseases are caused bymodern lifestyles (environmental factors). Meanwhile, genetic factors could also be strongly involved in theonset of lifestyle-related diseases, since some individuals suffer from lifestyle-related diseases while otherswith a similar lifestyle do not. A combination of multiple DNA polymorphisms is likely to affect the susceptibility
to lifestyle-related diseases. In this study, we examined the association between a DNA polymorphism andlifestyle-related diseases, focusing on peroxisome proliferators-activated receptors (PPAR) α gene.
PPARα belongs to the nuclear receptor superfamily, and plays an important role in lipid metabolism, fatty
acid oxidation, homeostasis and inflammation. In addition, some effects of dietary fish oil on the human bodyare considered to be mediated by PPARα.
Several polymorphisms of the human PPARα gene, such as Leu162Val polymorphism (leucine is substitutedfor valine at amino acid 162) and Val227Ala polymorphism (valine is substituted for alanine at amino acid227), have been reported in the Japanese and other ethnic populations. Recently, another PPARαpolymorphism, Gly395Arg (glycine is substituted for arginine at amino acid 395), was reported in Caucasians
and African subjects. The Gly395Arg site is located in the ligand-binding domain of the PPARα gene, which isimportant for binding ligands, sucha as fatty acid in dietary fish oil. In this study, we focused on the Gly395Arg
polymorphism. In collaboration with a pharmaceutrical company (BML, Japan), we established the Invader
assay method to search for the Gly395Arg polymorphism in the PPARα gene. We randomly selected 729
Japanese adults for the study. Although the synthesized oligonucleotides of each polymorphism could be
distinguished clearly, all 729 individuals had the Gly (G) allele and none had the Arg (C) allele. These datasuggest that there is racial variability in the frequencies of Gly395Arg polymorphisms, and also that the
Gly395Arg polymorphism is not common in the Japanese. Further studies are needed to investigate theassociation between other polymorphisms common in the Japanese and lifestyle-related diseases.

Fig. 1 Detection of Gly395Arg polymorphism by Invader
Assay for synthesized DNA ([G] contains G nucleotide and[C] contains C nucleotide) and in 12 Japanese samples. All
samples showed predominant green signals, indicating
they are homozygotes for G nucleotide (Gly).

Gly395Arg polymorphism of PPARα gene was not detected in Japanese populationof 729 individuals.
Journal of Nutrition Science and Vitaminology. 2006; 52: 75-78.
Kamei Y1),2), Saito K1),3), Yokoyama T3), Yoshiike N1), Ezaki O1) and Tanaka H1)
1)

Division of Food Science, National Institute of Health and Nutrition, Tokyo, Japan.

2)

Tokyo Medical and Dental University, Tokyo, Japan

3)

National Institute of Public Health, Saitama, Japan

Abstract:
Peroxisome proliferator-activated receptor a (PPARα) is a member of the nuclear receptor
superfamily and participates in the regulation of key proteins involved in lipid metabolism, fatty acid oxidation,
homeostasis, and inflammation. Several polymorphisms of the human PPARα gene, such as Leu162Val
polymorphism and Val227Ala polymorphism, have been described in different races. Recently, another
PPARα polymorphism Gly395Arg polymorphism has been reported in Caucasian and African subjects. Using
the Invader assay, we searched for this polymorphism in 729 Japanese adults randomly selected in a rural
population. Although the synthesized oligonucleotides of each polymorphism could be distinguished clearly,
all 729 individuals had the Gly (G) allele and none had the Arg (C) allele. These data suggest that there is
racial variability in the frequencies of PPARα gene polymorphisms.
5Latest Research
New Quantitative Index for Dietary Diversity and its annual changes in Japan.
Yasuhiro Matsumura (Project for Health Communication)
It is recommended to take the necessary nutrients from various foods. This is called as “dietary diversity”,
though there is no universal index by which dietary diversity can be evaluated. Many previous studies have used
the number of foods (food groups) consumed during a given period as an index. Because there is no uniformity
as to what types of foods are counted and by what method, objective comparison across different populations ortime points is difficult. Furthermore, only the number of consumed foods (food groups) can not fully describe
quantitative variations of consumed foods. Therefore, this report proposes a new index that takes into
consideration the quantitative aspect of consumed foods, by which objective evaluation of dietary diversity
across different populations or time points can be possible. We applied this index to the data obtained from the
National Nutrition Survey in Japan (J-NNS) between 1957 and 2000, and examined its annual changes. The
newly proposed Quantitative Index for Dietary Diversity (QUANTIDD) can be shown in the following formula,where prop (j) is the proportion of food group(s) j that contribute tototal energy or nutrient intake, n is the number of food groups.
This index ranges from 0 to 1. When the food intake sources areequally distributed over all the food groups that constitute them, the
QUANTIDD has a maximum value of 1; when the food intake sources
are unbalanced and leaning toward only one food group, theFigure 1
QUANTIDD has a minimum value of 0 (Figure 1).
We applied this QUANTIDD to the officially released results of
J-NNS between 1957 and 2000 (In this study, the numbers of foodgroups examined were 16). The QUANTIDD of energy intake wasabout 0.53 in the late 1950s and increased to about 0.8 from the
1960s to the 1970s.Thereafter it continued to gradually increase(Figure 2). This figure indicates that, as the years passed, theenergy intake sources became less unbalanced. The QUANTIDD ofamount of food intake was about 0.83 in the late 1950s andincreased by about 0.1 from the 1960s to the first half of the 1970s.
It has subsequently been hovering at around 0.93. The value of the
QUANTIDD of energy intake is smaller than that of weight intake,
Figure 2
because some food groups, such as the vegetable and seaweed,
make only a small contribution to energy. Although this study
calculated the QUANTIDD in terms of total energy or amount intake
only, this index can be calculated for diversity within any food group.
Combining these calculations will lead to a detailed understanding of
dietary diversity.
It must be noted however that, while this index reflects aquantitative aspect of dietary diversity, it does not necessarily reflectdietary quality. Besides, when the QUANTIDD is compared withother groups, the study foods (food groups) should be same
between groups. Considering these restrictions, we would like you
to utilize the QUANTIDD.

New Quantitative Index for Dietary Diversity (QUANTIDD) and its annual changes in theJapanese.
Nutrition. 2006; 22: 283-287
Katanoda K 1), Kim HS 2) and Matsumura Y2)
1) Division of Health Informatics and Education, National Institute of Health and Nutrition, Tokyo, Japan
2) Department of Food Science and Nutrition, Soonchunhyang University, Asan, Republic of Korea

Abstract:
OBJECTIVE: A diverse diet is recommended in many dietary guidelines. However, because there
are no unified standards for measurement methods, objective comparisons across different populations or time
points is difficult. This report proposes a new dietary diversity index based on quantitative distribution of
consumed foods to allow objective measurement of dietary diversity. METHODS: A Quantitative Index for
Dietary Diversity (QUANTIDD) is proposed: QUANTIDD=(1-summation operatorjn prop[j]2)/(1-1/n), whereprop(j) is the proportion of food group(s) j that contributes to total energy or nutrient intake, n is the number offood groups, and j = 1,2,...,n. The numerator is the probability that the two foods taken out of an aggregation of
consumed foods belong to different food groups. The denominator is its maximum value. The index ranges from0 to 1. By using the officially released average data from the National Nutrition Survey in Japan from 1957 to2000, we investigated annual changes in the QUANTIDD. We also investigated the distribution of the index byusing individual data from the National Nutrition Survey in Japan in 1996. RESULTS: The QUANTIDD increased
from the 1960s to the 1970s. This was the era of rapid economic growth in Japan, during which the dietary habitsof the Japanese underwent rapid changes. The distribution of the QUANTIDD was skewed to the left, but
logit-transformation decreased this asymmetry and made it similar to a normal distribution. CONCLUSION:
Because this index can measure dietary diversity objectively and is suitable for statistical handling, it is useful asa method to compare dietary patterns across different populations or time points.
6Latest Research
Effects of isoflavone and exercise on BMD and fat mass in postmenopausal Japanese women:a 1-year randomized placebo-controlled trial.
Yoshiko Ishimi (Project for Bio-index)% change% change

With advent of the aging society, the increased prevalence of osteoporosis became a significant public health problem inJapan. Determinants of bone mass include genetic predisposition, hormone, nutrition, exercise and lifestyle. In particular,
estrogen inhibits absorption in bone and the reduced estrogen secretion by menopause would cause a rapid bone loss.
Osteoporosis is a skeletal disorder characterized by bone loss and deterioration of bone microstructure, which predisposes a
person to the increased risk of fracture. It is reported that about half the Japanese women experience the bone fractureassociated with osteoporosis in their lifetime. Once an old person gets bone fracture, s/he is likely to become bed ridden,
which would greatly affect one’s quality of life (QOL). Now, the Ministry of Health, Labour and Welfare implements various
programs to increase healthy old persons, of which prevention of bone fracture is regarded as the most important strategy.
The most effective methods to prevent osteoporosis are to increase peak bone mass to the maximum in one’s youth, andalso to suppress the bone loss in one’s midlife. Exercise is one of the preventive methods of osteoporosis which can bepracticed in one’s daily life. However, for women, estrogen deficiency decreases bone response to exercise. We therefore
examined the combined effects of soy isoflavone intake and exercise on bone metabolism and lipid metabolism in the
postmenopausal Japanese women. In this study, 136 healthy postmenopausal women who were within 5 years of natural
onset of menopause were recruited, and were randomly assigned to four groups: 1) placebo, 2) placebo + walking (45minutes/day at 6km/h, 3 days/week), 3) isoflavone (isoflavone glycosides equivalent to 2/3 of tofu) and 4) isoflavone +walking. After 1 year Intervention, bone mineral density (BMD), fat mass and serum lipid were assessed. BMD in femur
decreased in placebo group, whereas walking showed significant effects on the preservation of BMD in the total hip and at
Ward’s triangle which consists of trabecular bone. Interventions with isoflavone moderately preserved BMD at Ward’s
triangle. And, isoflavone intake + walking preserved BMD in the total hip and also increased BMD at Ward’s triangle (Figure).
On the other hand, fat mass increased in placebo group, whereas it decreased in the whole body, trunk, legs and arms forwalking group (right Figure for the whole body). Isoflavone intake suppressed the abdominal fat accumulation. Interestingly,
the HDL-cholesterol concentration significantly increased in the walking group. These findings would suggest that daily
intake of isoflavone combined with walking exercise
could have a positive effect on BMD and lipid metabolism
BMD at Ward’s Triangle
Fat mass of whole bodyin postmenopausal Japanese women. No significant
Walking effectWalking effectchange of serum concentrations of estradiol wasobserved in any group. Soybean contains not only
isoflavone but also soy protein that decreases thecholesterol concentration. Walking exercise 3 times/week
together with adequate intake of soy products could havea greater effect on preventing lifestyle-related diseases
isoflavone effectsuch as osteoporosis, obesity and hyperlipidemia inpostmenopausal women. Needless to say, it is essential
PlaceboWalking
to keep a balanced diet with high Ca content, as well.
Isoflavone
Combined

Effects of isoflavone and exercise on BMD and fat mass in postmenopausal Japanese women:a 1-year randomized placebo-controlled trial.
Journal of Bone and Mineral Research. 2006; 21(5): 780-789
2

3

3

4

3

1

1

5

1

1

Wu J1, Oka J , Tabata I , Higuchi M , Toda T , Fuku N , Ezaki J , Sugiyama F , Uchiyama S , Yamada K ,Ishimi Y
1. Division of Applied Food Research, National Institute of Health and Nutrition, Tokyo, Japan
2. Division of Applied Nutrition, National Institute of Health and Nutrition, Tokyo, Japan
3. Division of Health Promotion and Exercise, National Institute of Health and Nutrition, Tokyo, Japan
4. Fujicco Co.td., Kobe, Japan, 5. Saga Nutraceutical Research Institute, Otsuka Pharmaceutical Co. Ltd., Saga, Japan

Abstract: The combined intervention of isoflavone intake and walking exercise over 1 year in postmenopausal Japanesewomen exhibited a trend for a greater effect on prevention of bone loss at the total hip and Ward's triangle regions.
INTRODUCTION: The additive effects of isoflavones and exercise on bone and lipid metabolism have been shown inestrogen-deficient animals. In this study, we determined the effects of isoflavone intake, walking exercise, and theirinteraction on bone, fat mass, and lipid metabolism over 1 year in postmenopausal Japanese women. MATERIALS AND
METHODS: A total of 136 postmenopausal women at <5 years after the onset of menopause were randomly assigned to fourgroups: (1) placebo, (2) walking (45 minutes/day, 3 days/week) with placebo, (3) isoflavone intake (75 mg of isoflavone
conjugates/day), and (4) combination of isoflavone plus walking. BMD, fat mass, serum lipid, and serum and urinary
isoflavone concentrations were assessed. RESULTS: A significant main effect of isoflavone on the reduction in trunk fat
mass was obtained at 12 months. Significant main effects of walking on the reduction in fat mass in the whole body and thetrunk were observed at 3, 6, and 12 months and that in the legs and arms at 6 and 12 months. Serum high-density lipoprotein(HDL)-cholesterol concentration significantly increased by 12 months after the walking and the combined intervention. After
12 months, a significant main effect of isoflavone on BMD was observed only at Ward's triangle. Walking prevented boneloss at the total hip and the Ward's triangle to significant degrees. The effect of the combined intervention on BMD at total hip
and Ward's triangle regions was greater than that of either alone. No significant interaction was observed between isoflavone
and walking in any measurements recorded during the study . CONCLUSIONS: Our study suggest that combinedintervention of 75 mg/day of isoflavone intake and walking exercise 3 times/week for 1 year showed a trend for a greater
effect on BMD at total hip and Ward's triangle regions than either alone. Intervention with isoflavone in postmenopausal
Japanese women showed a modest effect on BMD compared with those in Westerners. Further studies over longer
treatment duration that include assessment of BMD at various regions are necessary to ascertain the clinical significance ofthe combined intervention of isoflavone plus walking in postmenopausal women.

7Latest Research
A new attraction of sea food: Taurine deficiency creates a vicious cycle promoting
obesity
Nobuyo Tsuboyama-Kasaoka (Nutritional Sciences Program)
It is speculated that a fish- rather than meat-based diet is beneficial in one’s health. In fact, there are evidencesfrom the researches on nutrients contained in fish and seafood. Taurine is one of the amino acids, which iscontained in sea foods like oyster, squid etc. It is known that dietary taurine improves the functions of heart andliver, and reduces the cholesterol level in blood. Yet, its effect on obesity has been still unclear.
Taurine can be obtained by dietary ingestion, as well as by de novo synthesis. The key enzyme in the taurine
biosynthetic pathway is cysteine dioxygenase (CDO) in the liver. In addition, the previous studies explored that
CDO mRNA is also expressed in white adipose tissue (WAT). Interestingly, the biosynthesis of taurine in WAT
was observed in the mice who became obese by high-fat diet. Since blood taurine concentration also
decreased, it was likely that obese mice would become taurine deficient.
In this study, we found that even high fat diet did not lead to obesity, when it was supplemented with taurine(Figure 1). In taurine-fed mice, the basal metabolic rate increased and gene expression involved in lipolysis also
increased in WAT. It can be therefore assumed that taurine may work on fat combustion. An excessive fat
accumulation in WAT would cause depletion of the blood taurine concentration, which then promotes further
obesity, creating a vicious circle (Figure 2). Dietary taurine supplementation interrupts this vicious circle andmight prevent obesity, by enhancing the weakened function of blood taurine.
According to the latest studies, WAT is known not only for its function to accumulate fat, but also as adipocytes
where hormone-like adipocytokines are secreted. Thus, although not a classical hormone, taurine could be a
new adipocytikine with the effects of preventing obesity and diabetes. This is an interesting phenomenon that anutrient could adjust the physical function like this.
It must be noted, however, that out results were derived from high-fat diet fed mice with lots of taurine(equivalent to 150g taurine for a person with 50kg body weight). Further studies are needed to examine theeffectiveness of taurine supplementation in obese human subjects.
Figure 2. Proposed model of taurine-mediatedvicious circle in obesity

Figure 1. After 18 weeks of experimental feeding

High-carbohydrate
Diet fed miceHigh-fat dietfed mice

High-fat diet
+ taurine fed

Taurine (2-aminoethanesulfonic acid) deficiency creates a vicious circle promoting obesity.
Endocrinology, 2006; 147:3276-3284
Tsuboyama-Kasaoka N1, Shozawa C1, Sano K2, Kamei Y3, Kasaoka S1, Hosokawa Y4 and Ezaki O1
1. Division of Clinical Nutrition, National Institute of Health and Nutrition, Tokyo, Japan
2. Department of Health and Nutrition, Bunkyo University Women’s College, Kanagawa, Japan
3. Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
4. Department of Food and Health Sciences, Jissen Women’s University, Tokyo, Japan

Abstract:
The relation between blood taurine (2-aminoethanesulfonic acid) concentrations and obesity was investigated.
Taurine is supplied to the body by dietary ingestion as well as by de novo synthesis; it is anabolized by cysteine
dioxygenase (CDO), which is abundantly expressed in liver and white adipose tissue. Overexpression of CDO in
3T3-L1 preadipocytes caused a decrease in the level of cysteine (precursor of taurine) and an increase in thelevel of taurine in the culture medium, suggesting that CDO is involved in biosynthesis and secretion of taurine inwhite adipose tissue. In high-fat diet-induced and/or genetically obese mice, a decrease in the blood taurine
concentration was observed along with a decrease in CDO expression in adipose tissue but not in liver. Dietarytaurine supplementation prevented high-fat diet-induced obesity with increased resting energy expenditure.
Thus, taurine deficiency observed in association with obesity may create a vicious circle promoting obesity.
Dietary taurine supplementation interrupts this vicious circle and may prevent obesity.

8