J Nutr Sci Vitaminol, 65, S122–S124, 2019

Effect of Continuous Dewaxed Brown Rice Ingestion on theCognitive Function of Elderly Individuals
Maya Uenobe1,2, Toshiyuki Saika3, Natsumi Waku2,4,Masae Ohno5 and Hiroyuki Inagawa6,7
1

Faculty of Health and Human Development, Department of Food and Health Sciences,
The University of Nagano, Nagano, Japan
2
Course of Nutrition Management, Graduate School of Human Life Science,
Nagoya University of Economics. Aich Japan
3Toyo Rice Corporation., Wakayama, Japan
4Social Welfare Corporation Tanpopo Welfare Association TSURU no Sato,
Special Nursing Home for the Elderly, Aich, Japan
5
Social Welfare Corporation Nishikasugai Welfare Association Heiann no Sato,
Special Nursing Home for the Elderly, Aich, Japan
6
Research Institute for Healthy Living, Niigata University of Pharmacy andApplied Life Sciences, Niigata, Japan
7
Control of Innate Immunity, Technology Research Association, Kagawa, Japan

Summary Dewaxed brown rice (DBR), which is prepared by removing only the outermost
wax layer of brown rice using a new rice milling technique, has improved water absorbency,
digestibility, and taste compared to regular brown rice. DBR has a nutritional value close
to that of brown rice, including a rich amount of lipopolysaccharides that are known toimprove cognitive function in mice. This study thus aimed to verify the influence of continuous DBR ingestion on cognitive function among elderly individuals. The present study
employed a crossover comparison design using the Revised Hasegawa Dementia Scale toassess cognitive function. Our findings confirmed that long-term DBR ingestion contributed
to the prevention and reduction of overall cognitive decline, especially among elderly individuals with low cognitive function. Thus, DBR has the potential to be a useful staple foodthat maintains brain homeostasis among elderly individuals.
Key Words dewaxed brown rice, cognitive function, lipopolysaccharide, elderly

A recently developed type of brown rice calleddewaxed brown rice (DBR), wherein only the outermost
wax bran layer have removed using a new rice milling
technique (1). Furthermore, DBR can be cooked as easily as polished white rice (WR) and can be added to any
diet in the form of porridge or rice meal.
We have previously demonstrated that lipopolysaccharide (LPS) in DBR can activate macrophages primarily through the Toll-like receptor 4 pathway and, to alesser extent, the Toll-like receptor 2 pathway (2). LPS
are the primary component of the outer membrane ofgram-negative bacteria (e.g., Acetobacter aceti, Zymomonas mobilis, and Xantomonas campestris), which are
symbionts of edible plants, such as cereals, vegetables,
rice, wheat, and soybean. Reports have shown that LPS
extracted from plants activate macrophages (or immunecells), while oral LPS ingestion produces various physiologically active effects (3–5).
Experiments using senescence-accelerated mouseprone 8 (SAM-P8) mice have revealed that oral LPS
administration activates brain microglia, enhances thephagocytosis of amyloid b, a cause of Alzheimer’s disease, and markedly decreases memory impairment (6,7). Thus, continuous ingestion of LPS-containing DBR
E-mail: uenobe.maya@u-nagano.ac.jp

as a staple food may be useful in slowing or even preventing the deterioration of cognitive function. However, the effects of DBR on the cognitive function ofelderly individuals remain unclear. Hence, this studyaimed to investigate the effects of continuous DBR
ingestion as a staple food on cognitive function among
elderly individuals.
Materials and Methods
Study Design. A crossover comparison trial was conducted on 31 elderly residents of special nursing homes
who were divided into two groups. Both groups ingested
WR and DBR for 6 mo (three meals a day). Cognitivefunction was assessed before and 6 mo after the startof the trial using the Revised Hasegawa Dementia Scale(HDS-R) (8) (Fig. 1). This study protocol complied withthe Code of Ethics of the World Medical Association(Declaration of Helsinki) and was approved by the Ethics Committee of Nagoya Keizai University, Aichi, Japan(Receipt No. 2016-1).
Dietary Intervention. Koshihikari WR from Aichi
Prefecture was used, while Koshihikari raw material from Niigata Prefecture was used to produce DBR,
which was process by Toyo Rice Corp. (Saitama, Japan).
The nutritional value of WR was calculated using theStandard Tables of Food Composition in Japan—2017

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Dewaxed Brown Rice Improves Elderly Cognitive Function
Table 2.

Fig. 1. Study design. A controlled crossover trial wasconducted on 31 elderly individuals in special nursing
homes who were divided into two groups and ingested
either dewaxed brown rice (DBR) or white rice (WR)three times a day for 6 mo, followed by the ingestionof the other test food for the next 6 mo. Cognitive function was assessed prior to and 6 mo after each test mealintake using the Revised Hasegawa dementia scale.

Table 1.

Nutrients

WRDBR

Calorie (kcal)
Protein (g)Fat (g)Carbohydrate (g)Dietary fiber (g)LPS (ng)

40.6
0.1
9.4
0.1
0.04

4
0.5
0.2
6.5
0.40.81

WR, white rice; DBR, dewaxed brown rice; LPS, lipopolysaccharide. Component values are indicated per 1 g dryweight.
Table 3.

Revised Hasegawa Dementia Scale.

Nutritive values of WR and DBR diets.

Participant characteristics.

Score

Variable

1. Age (self-orientation)
2. Date (date orientation)
3. Place (place orientation)
4. Repeating of three words (working memory)
5. Serial subtractions of 7 s (calculation)
6. Digits backward (working memory)
7. Recalling of three words (short-term memory)
8. Recalling five objects (visual memory)
9. Word fluency (fluency)

142
322
655

Number (men/women)
Age (y)Body weight (kg)BMI (kg/m2)
HDS-R

Total score

30Questions

Group AGroup B

18 (4/14) 13 (3/10)
84.360.3 83.869.1
44.5610.0 47.368.9
19.065.5 18.867.0
7.1610.0 8.066.9

p0.768
0.428
0.922
0.785

BMI, body mass index; HDS-R, Revised Hasegawa Dementia Scale. Data are presented as mean and standard deviation, while p values were obtained using Student’s t-test.

Table 4. Difference in total HDS-R score between eachgroup.

(Seventh Revised Edition), the nutritional value of DBR
was measured by the Japan Food Industry Association, and LPS content was measured by Macrophi Inc.
(Kagawa, Japan).
Cognitive Function. The HDS-R (8), which wasadministered prior to and 6 mo after each test mealintake, was used to assess cognitive function. HDS-R is
a test developed to screen for age-associated dementia(8) and comprises nine simple items that measure orientation, memory, attention/calculation, and fluency ofwords, with a maximum total score of 30 points (Table1).
Statistical Analysis. Data were analyzed using SPSS
version 24.0 (IBM Corporation, Tokyo, Japan) for Windows. Values for participants’ characteristics are presented as means and standard deviations, while HDS-R
scores are presented as means and standard errors. The
present study categorized subjects into low and highcognitive function groups, the former including subjects
with a total HDS-R score of 1 or more and less than 10.
Paired t-tests were used to assess the statistical significance of HDS-R scores and differences between pairedchanges in both groups. A p value of ,0.05 in all tests
was considered statistically significant.
Results
Diet Parameters. Total calorie consumption was thesame for DBR and WR. Protein contents were 0.5 and0.6 g and fat contents were 0.2 and 0.1 g for DBR andDifference in total score of HDS-R

Group AGroup B
Group A1B

White rice

Dewaxedbrown rice

1.660.7
21.060.8
0.560.6

1.160.9
1.360.9
1.260.6

p0.6830.063
0.441

HDS-R, Revised Hasegawa Dementia Scale. Data are presented as mean and standard error, while p values wereobtained using the paired t-test. Group A, n518; GroupB, n513; Group A1B, n531.

WR, respectively. Carbohydrate contents were 6.5 and9.4 g and dietary fiber contents were 0.4 and 0.1 g for
DBR and WR, respectively. LPS contents in the DBR andWR diets were 0.81 and 0.04 ng, respectively (Table 2).
Participants’ Characteristics. Table 3 summarizes theparticipants’ characteristics, among whom 18 were ingroup A and 13 were in group B. No significant differences in the characteristics of the two cohorts had been
observed.
Cognitive Function Assessment Using the HDS-R. Table
4 shows the difference in total HDS-R score between eachgroup. Group B had a score difference of −1.060.8 after
WR ingestion and 1.360.9 after DBR ingestion. However, no significant difference in total score was observed
between WR and DBR in Groups A, B, and A1B. Table

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Uenobe M et al.

Table 5. Difference in total HDS-R score among the low
cognitive function group.

White rice
Dewaxed brown rice

Difference in total
HDS-R score

p20.560.5
2.860.7

0.001

HDS-R, Revised Hasegawa Dementia Scale. Data are presented as mean and standard error, while the p value wasobtained using the paired t-test. The low cognitive function group (n513) included subjects with a total HDS-R
score of 1 or more and less than 10.

5 shows the difference in total HDS-R scores among thelow cognitive function group (total HDS-R score of 1 ormore and less than 10). Accordingly, the score difference was 20.560.5 after WR ingestion and 2.860.7
after DBR ingestion. In this group, however, DBR ingestion resulted in a significant higher total HDS-R scorecompared to WR ingestion (paired t-test, p50.001).
Discussion
This study investigated the effect of long-term regular dietary intake of DBR on the cognitive function ofelderly individuals. To the best of our knowledge, thishas been the first human intervention study to utilize
DBR, a substance which has generally been considereddifficult to ingest, especially for elderly individuals withdeteriorated chewing or swallowing capabilities. However, throughout the study period, none of the subjects
dropped out of the program, indicating that DBR wasregularly ingested in our study cohort. In addition, ourfindings revealed that long-term DBR ingestion contributed to the prevention and reduction of overall cognitive decline, especially among elderly individuals withlow cognitive function. We hypothesized that LPS, thenutrient-rich functional component of DBR, can be useful for maintaining brain homeostasis. However, theeffects of LPS in DBR and other food components onhuman microglia and brain function, as well as theirmechanisms of action, remain unknown. Moreover,the nutritional components of rice have been known tofrom area-by-area even in the same brand. In the future,
analyzing the nutritional components of rice and using
rice harvested in the same area to produce WR and DBR.
Visual assessment of the amount of WR or DBR consumed daily by the individuals had also been conducted(data not shown). Accordingly, the relationship between
the results provided herein and the amount of rice consumed by the individuals should also be analyzed. Considering that medical history, drug intake history, andgenetic background had not been screened herein, careshould be taken in the interpretation of the results. Furthermore, we need to consider the fact that DBR contains other bioactive compounds, such as polyphenols,vitamins, and dietary fiber. Nonetheless, we believe thatLPS is a major functional component of DBR and speculate that the interaction between LPS and other functional components contributed toward improving cognitive function—a topic that our future investigations will
cover. Future studies that seek to investigate the association between BR intake and cognitive function should
objectively evaluate the effects of long-term DBR intake.
Disclosure of State of COI
TS is an employee of Toyo Rice Corp. All the otherauthors declared no competing interests. This study corresponds to “For scholarships provided by a company ora for-profit organization related to the relevant research,when the total amount paid from the company or organization to an author is 1,000,000 yen or over a year.”Acknowledgments
This study was funded by a scholarship donation toNagoya University of Economics by Toyo Rice Corp.,
Wakayama, Japan.
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