nutrients

Article

Association between Serum Concentration of Carotenoid and Visceral Fat

Mai Matsumoto ^1,*, Hiroyuki Suganuma ¹ , Naoki Ozato ^2,3 , Sunao Shimizu ^1,4,5 , Mitsuhiro Katashima ^2,3 Yoshihisa Katsuragi ^2,3, Tatsuya Mikami ⁵, Ken Itoh ^4,6 and Shigeyuki Nakaji ^5,7
,

1

Innovation Division, KAGOME CO. LTD., 17 Nishitomiyama, Nasushiobara, Tochigi 329-2762, Japan; [email protected] (H.S.); [email protected] (S.S.) Department of Active Life Promotion Sciences, Graduate School of Medicine, Hirosaki University,

2

5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan; [email protected] (N.O.); [email protected] (M.K.); [email protected] (Y.K.) Health & Wellness Products Research Laboratories, Kao Corporation, Tokyo 131-8501, Japan

34

Department of Vegetable Life Science, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan; [email protected]

5

Innovation Center for Health Promotion, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan; [email protected] (T.M.); [email protected] (S.N.)

Department of Stress Response Science, Center for Advanced Medical Research, Graduate School of Medicine,

Hirosaki University, 5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan Department of Social Medicine, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan

67

*

Correspondence: [email protected]; Tel.: +81-80-1581-1874

Abstract: Consumption of fruits and vegetables rich in carotenoids has been widely reported to

prevent cardiovascular diseases. However, the relationship between serum carotenoid concentrations

and visceral fat area (VFA), which is considered a better predictor of cardiovascular diseases than

the body-mass index (BMI) and waist circumference, remains unclear. Therefore, we examined the

relationship in healthy individuals in their 20s or older, stratified by sex and age, to compare the

relationship between serum carotenoid concentrations and VFA and BMI. The study was conducted

on 805 people, the residents in Hirosaki city, Aomori prefecture, who underwent a health checkup.

An inverse relationship between serum carotenoid concentrations and VFA and BMI was observed

only in women. In addition, the results were independent of the intake of dietary fiber, which is

mainly supplied from vegetables as well as carotenoids. This suggests that consumption of a diet rich

in carotenoids (especially lutein and beta-carotene) is associated with lower VFA, which is a good

predictor of cardiovascular disease, especially in women. This study is the first to comprehensively

evaluate the association between serum carotenoid levels and VFA in healthy individuals.

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Citation: Matsumoto, M.; Suganuma,

H.; Ozato, N.; Shimizu, S.; Katashima, M.; Katsuragi, Y.; Mikami, T.; Itoh, K.; Nakaji, S. Association between Serum Concentration of Carotenoid and Visceral Fat. Nutrients 2021, 13, 912. https://doi.org/10.3390/nu13030912

Academic Editor: Antonio Pérez-Gálvez

Received: 29 January 2021 Accepted: 8 March 2021 Published: 11 March 2021

Keywords: carotenoid; visceral fat; metabolic syndrome; vegetable intake; resident-based cross-

sectional study; healthy subjects

Publisher’s Note: MDPI stays neutral

with regard to jurisdictional claims in published maps and institutional affiliations.

1. Introduction

Carotenoids are red, orange, and yellow pigments widely distributed among plants,

animals, and microorganisms. Because carotenoids have a strong ability to quench singlet

oxygen, their ingestion is expected to prevent and improve various diseases in which reactive oxygen species (ROS) are involved in the onset or exacerbation of symptoms.

Many studies have been conducted in this regard. Several epidemiological studies have

shown that ingestion of carotenoids and carotenoid-rich vegetables and fruits leads to the amelioration of arteriosclerosis and hypertension and reduces the risk of chronic

Copyright:

• ©
• 2021 by the authors.

Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

cardiovascular diseases, such as ischemic heart disease and cerebrovascular disease [

We also found that the higher the levels of carotenoids in the blood and skin, the healthier

are many predictive markers of chronic cardiovascular disease in healthy individuals [ ],

1–7].

8,9

• Nutrients 2021, 13, 912. https://doi.org/10.3390/nu13030912
• https://www.mdpi.com/journal/nutrients

Nutrients 2021, 13, 912

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suggesting that vegetable intake may be preventive against diseases in healthy as well

as ill individuals. In addition to their role in reducing oxidative stress, some carotenoids

have an inhibitory effect on the differentiation and hypertrophy of adipocytes [10], and

some affect lipid and glucose metabolism [11,12]. Thus, copious intake of carotenoid-rich

vegetables is also expected to inhibit metabolic syndrome (visceral fat syndrome), which is

a crucial trigger of chronic cardiovascular disease and is thought to be important for its

prevention [13].

Visceral fat area (VFA) is commonly measured by computed tomography (CT). How-

ever, because of the involvement of X-ray radiation, this measurement is not readily feasible.

Therefore, the relationship between carotenoids and obesity was limited to the body-mass

index (BMI) or waist circumference-based assessments. For example, in our previous study [8], high BMI was associated with low serum concentration of total carotenoid, whereas Suzuki et al. have reported an association between high waist circumference and low serum β-carotene levels in females [14]. Carotenoid concentrations in adipose

tissue have also been measured, which have been shown to be related to waist circumfer-

ence [15]. Sato et al. reported that there were misjudgments of more than 20% when they

judged whether the VFA was equal to or larger than 100 cm² using the criteria of waist

circumference [16], so measuring VFA itself rather than waist circumference is considered

preferable for subsequent disease prevention. However, as mentioned earlier, due to the

difficulties in the measurement of VFA, the relationship between carotenoids and VFA has

been evaluated only in a few previous studies [17]. The relationship between carotenoid intake, calculated from the food frequency questionnaire (FFQ), and VFA was evaluated

in a few studies, wherein it was found that the higher the intake of β-carotene and ly-

copene, the lower the VFA in middle-aged and older men [17]. However, there has been

no comprehensive assessment of the relationship between VFAs and levels of different

carotenoids in the blood. To our knowledge, the age group for which the evaluations have

been performed are also limited, and the studies evaluating a wide range of age groups,

including younger age groups, are lacking.

Ryo et al. developed a noninvasive, easy-to-measure method for VFA, the results of

which highly correlate with the measurements by CT [18]. They evaluated the relationship

between VFA levels measured using the device developed by them and various biomarkers and environmental factors relevant to the field of medical examination and found a negative

relationship between VFA and intake of dietary fiber (total and water-soluble), mainly

taken through vegetables, as well as carotenoids [19]. However, the relationship between

carotenoids and VFA has remained unclear.

In this study, we evaluated the relationship between serum carotenoid levels and
VFA, including dietary habits, such as dietary fiber intake, in healthy individuals who

participated in the Iwaki Health Promotion Project, a health examination project for a wide

range of age groups.

2. Materials and Methods

2.1. Study Design and Subjects

This cross-sectional study was based on an annual health examination (the Iwaki
Health Promotion Project) for the residents of the rural area of Hirosaki city, Aomori prefecture, Japan, conducted by Hirosaki University in May and June 2015. Of all participants (n = 1113), 805 (310 males and 495 females) were included as healthy subjects

(Figure 1). Complete clinical data were available for these subjects, and they were not on

any medication for dyslipidemia and had no history of serious diseases, such as cancer, stroke, cardiovascular diseases, liver diseases, kidney diseases, or diabetes. All proce-

dures, including subject recruitments, were conducted in accordance with the Declaration

of Helsinki and were approved by the ethics boards of Hirosaki University School of Medicine (2014-377, 2016-028) and KAGOME CO., LTD. (2015-R04). Written informed

consent was provided by all subjects. This work has also been registered in the public in-

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formation database UMIN-CTR by Hirosaki University and Kao Corporation (registration

number: UMIN000030351).

Figure 1. Flowchart for the recruitment of participants.

2.2. Body Measurements

We measured VFA using the EW-FA90 (Panasonic Corporation, Osaka, Japan) based

on an abdominal bioimpedance method developed at the Kao Corporation. BMI was calculated from the body weight and height, which were obtained by anthropometric

measurements.

2.3. Self-Administered Questionnaire

On the day of the health examination, we collected the self-developed questionnaires

that the participants had filled out in advance. The questionnaire contained information

about sex, age, current smoking habits, exercise habits, medical history, and medications.

We defined an exerciser as a person who habitually exercised at least 30 min a day and at

least twice a week throughout the year. The volume of food consumed (g/day), including

alcohol intake, was estimated using a brief-type self-administered diet history questionnaire

(BDHQ) [20]. The daily intake for key food groups is calculated using BDHQ based on the

past month’s dietary surveys.

2.4. Blood Sampling and Testing

Blood was collected from the median cubital vein after overnight fasting. The serum

carotenoids were quantified at KAGOME CO., LTD. (Nagoya, Japan). Carotenoids (lutein, zeax-

• anthin,
• β-cryptoxanthin,
• α-carotene,
• β-carotene, and lycopene) were extracted and measured

in accordance with the methods described previously [21,22]. We used a high-performance liquid chromatograph with a photodiode array detector (Prominence LC-30AD/Nexera X2

SPPD-M30A, SHIMADZU CORPORATION, Kyoto, Japan) for the measurements.

2.5. Statistical Analyses

As described in our previous report [8], the mean value of each measurement was stratified by sex (male and female) and compared using Student’s t-test. It was also

Nutrients 2021, 13, 912

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stratified by age category (young, 20–39 years; middle-aged, 40–59 years; old ≥60 years) and compared using one-way ANOVA (post hoc: Bonferroni). Because previous studies

have shown that carotenoid concentrations do not follow normality [8], Mann–Whitney U

test and Kruskal–Wallis test (post hoc: Bonferroni) were used for the carotenoids.

Correlation analysis between serum concentrations of carotenoids and other factors

(VFA, BMI, and foods) stratified by sex was performed using Pearson’s correlation coefficient.

Multiple regression analysis stratified by sex and age was conducted to evaluate the

relationships between the serum concentrations of carotenoids and VFA or BMI. VFA and

BMI were adopted as objective variables, whereas carotenoids were adopted as explana-

tory variables. Age, use of medication for some diseases (hypertension, hyperlipidemia,

diabetes, dementia, rheumatism, and steroids), alcohol intake, current smoking habits,

exercise habits, and total dietary fiber intake were adopted as adjustment factors according

to the analysis. Analyses were performed using the R statistical package (version 3.5.1, R

Foundation for Statistical Computing, Vienna, Austria) and EZR (version 1.4) [23], and a

p-value < 0.05 was considered statistically significant.

3. Results

3.1. Characteristics of the Study Subjects

The mean values of all measurements stratified by sex and age categories are shown in

Table 1. Both smoking habit and exercise habit rates were higher in males than in females in total.

VFA and BMI were significantly higher in males in total. In males, VFA in the young

individuals was lower than that in the middle-aged and old individuals, and it increased

by age in females. BMI was significantly higher in old individuals compared with that in

young ones only in females.

Serum concentrations of carotenoids were higher in females except for zeaxanthin and lycopene. Concentrations of serum lycopene were significantly lower in the old in

both males and females. For most of the other carotenoids, the serum levels were higher in

middle-aged and old individuals than in the young ones.

Dietary fiber intake was higher in older age groups. The intake of carrots and pumpkin,

and root vegetables was higher in females than in males. For both males and females, the

intake of “radish/turnip” and “pickles” was higher in the old than in the other age groups.

3.2. Relationship between Serum Carotenoid Concentrations and VFA/BMI

Table 2 shows simple correlation coefficients between serum concentrations of carot-

enoids and VFA or BMI. The correlation coefficient between α-carotene and β-carotene

was found to be high in previous studies [

a representative for the assessment.

8], and the β-carotene concentration was used as

In males, neither VFA nor BMI showed significant correlations with either total carotenoids or individual carotenoids. In contrast, both VFA and BMI were negatively

• correlated with total carotenoids, lutein,
• β-carotene, and lycopene in females. BMI also had

a negative correlation with zeaxanthin in females.

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Table 1. Characteristics of the study subjects.

• Male
• Female

• Measurement Item
• All

Young

(20–39 Years)
Middle-Aged (40–59 Years)
Young
(20–39 Years)
Middle-Aged (40–59 Years)

• All
• Old (≥60 Years)
• All
• Old (≥60 Years)

N
Age, year

• 805
• 310

49.1 ± 14.8 21.8 ± 24.2
32.6

• 103
• 118

49.6 ± 5.5 25.8 ± 24.8
37.3
89
67.7 ± 5.8 19 ± 20.8
20.2

• 495
• 120

32.5 ± 5.1 4.3 ± 9.9
11.7

• 188
• 187

51.1 ± 14.8
11 ± 19
32.5 ± 4.6 19.8 ± 25.6
37.9
52.3 ± 14.6 ** 4.2 ± 10.1 ***
11.3
50 ± 5.8
6.2 ± 12.4
17.6
67.3 ± 5.8 2.3 ± 6.9 ^b
4.8
Alcohol intake, g/day

• Smoking, %
• 19.5

Habitual exercise, % Medication, %

• 9.2
• 11.3
• 12.6
• 11.9
• 9
• 7.9
• 9.2
• 6.9
• 8

• 19.3
• 16.5
• 2.9
• 13.6
• 36
• 21
• 0.8
• 11.2
• 43.9

• VFA, cm²
• 72.4 ± 32.49 ^ab

22.58 ± 3.28 ^a 1.84 ± 0.84 ^ab 0.41 ± 0.16 ^ab
0.06 ± 0.02
0.21 ± 0.12 ^ab
0.21 ± 0.17
0.74 ± 0.52 ^ab 0.21 ± 0.12 ^ab
79.11 ± 42.28 22.58 ± 3.46 1.47 ± 0.72 0.34 ± 0.14 0.06 ± 0.02 0.15 ± 0.1 0.17 ± 0.16 0.5 ± 0.42 0.25 ± 0.13
102.81 ± 44.96
23.61 ± 3.23 1.15 ± 0.53 0.3 ± 0.13 0.06 ± 0.02 0.11 ± 0.06 0.13 ± 0.14 0.3 ± 0.28 0.24 ± 0.13
92.2 ± 47.62 23.14 ± 3.86
1.07 ± 0.5 0.25 ± 0.1 0.06 ± 0.02 0.1 ± 0.05 0.13 ± 0.15 0.25 ± 0.25 0.28 ± 0.14
108.1 ± 41.09 ^a
24.13 ± 2.87 1.13 ± 0.53 0.31 ± 0.12 ^a 0.06 ± 0.02 0.1 ± 0.05 0.13 ± 0.13 0.28 ± 0.28 0.24 ± 0.12
108.07 ± 45.03 ^a
23.47 ± 2.8 1.28 ± 0.56 ^a 0.35 ± 0.15 ^a 0.06 ± 0.02
0.14 ± 0.08 ^ab
0.14 ± 0.14
0.39 ± 0.28 ^ab 0.19 ± 0.13 ^ab
64.27 ± 32.74 *** 21.94 ± 3.45 *** 1.67 ± 0.75 *** 0.36 ± 0.15 ***
0.06 ± 0.02
0.17 ± 0.11 *** 0.2 ± 0.16 *** 0.62 ± 0.44 ***
0.26 ± 0.14
53.13 ± 32.36 21.22 ± 3.95
1.5 ± 0.68 0.3 ± 0.11 0.06 ± 0.02 0.13 ± 0.06 0.21 ± 0.19 0.5 ± 0.36 0.3 ± 0.13
63.31 ± 31.13 ^a
21.76 ± 3.16 1.61 ± 0.68 0.35 ± 0.15 ^a 0.06 ± 0.02 0.17 ± 0.11 ^a 0.19 ± 0.12 0.57 ± 0.36 ^a 0.27 ± 0.13
BMI, kg/m²
Total carotenoid, µg/mL
Lutein, µg/mL Zeaxanthin, µg/mL β-Cryptoxanthin, µg/mL α-Carotene, µg/mL β-Carotene, µg/mL Lycopene, µg/mL
BDHQ
Total dietary fiber, g/day Soluble dietary fiber, g/day Insoluble dietary fiber, g/day Fresh vegetables, g/day Green leafy vegetables, g/day Carrot and pumpkin, g/day
Tomato, g/day
10.74 ± 4.40 2.66 ± 1.20 7.73 ± 3.05
11.11 ± 4.74 2.72 ± 1.32 8.04 ± 3.24
9.55 ± 3.52 2.33 ± 0.99 6.95 ± 2.50
10.58 ± 4.23 2.57 ± 1.18 7.67 ± 2.90
10.51 ± 4.16 2.62 ± 1.13
8.98 ± 3.75 2.26 ± 1.01 6.46 ± 2.61
10.36 ± 3.93 ^a 2.60 ± 1.08 ^a 7.42 ± 2.71 ^a 26.33 ± 19.04 31.95 ± 31.01 17.33 ± 14.01 20.25 ± 23.81 27.5 ± 23.32 13.47 ± 14.28 31.42 ± 24.36
4.15 ± 6.81
13.63 ± 5.56 ^ab 3.38 ± 1.56 ^ab 9.79 ± 3.72 ^ab 25.24 ± 21.89
29.4 ± 28.5
16.28 ± 13.39 0.58 ± 21.01 34.12 ± 33.34 20.4 ± 24.45 ^ab 32.83 ± 33.55
10.42 ± 12.67 ^ab
11.63 ± 4.33 ^ab
2.86 ± 1.19 ^a 8.37 ± 3.04 ^ab 24.25 ± 19.91 30.21 ± 28.89 20.22 ± 17.11 21.45 ± 24.79 32.1 ± 29.23
7.54 ± 2.90 * 24.8 ± 19.32 30.25 ± 29.04
18.36 ± 15.78 ***
19.95 ± 22.76 28.71 ± 25.76 15.31 ± 16.49 31.36 ± 24.18 *
5.6 ± 8.88

• 25 ± 19.88
• 25.31 ± 20.77

26.73 ± 27.81 14.23 ± 13.52 18.49 ± 19.96 30.27 ± 27.24 15.3 ± 18.84 27.52 ± 26.27
6.84 ± 9.05
23.94 ± 20.38 26.09 ± 24.93 12.9 ± 12.13 17.35 ± 19.82 26.29 ± 22.66 12.86 ± 13.64 24.74 ± 20.37
4.59 ± 5.33
26.56 ± 20.33 25.28 ± 29.7 13.84 ± 14.64 17.9 ± 19.31 30.84 ± 25.52 13.57 ± 17.25 25.95 ± 24.16
6.1 ± 7.5
23.26 ± 18.81 27.64 ± 25.94 17.08 ± 16.07 17.14 ± 16.98 25.34 ± 23.09 13.12 ± 14.23 30.29 ± 23.55
3.36 ± 6.37
28.89 ± 28.61 16.77 ± 15.07 19.39 ± 21.72 29.31 ± 26.34 15.31 ± 17.42 29.88 ± 25.06
6.08 ± 8.96
Cabbage, g/day
18.57 ± 19.25 ^ab
31.99 ± 24.49 8.5 ± 11.08 ^ab
Radish and turnip, g/day Root vegetables, g/day
Pickled green leafy vegetables, g/day