Kentaro Murakami¹, Satoshi Sasaki¹, Yoshiko Takahashi², Kazuhiro Uenishi³, Tomoko Watanabe⁴, Toshiyuki Kohri⁵, Mitsuyo Yamasaki⁶, Reiko Watanabe⁷, Keiko Baba⁸, Katsumi Shibata⁹, Toru Takahashi¹⁰, Hitomi Hayabuchi¹¹, Kazuko Ohki¹² and Junko Suzuki¹³

¹Department of Social and Preventive Epidemiology, School of Public Health, the University of Tokyo, Tokyo 113-0033, Japan. ²Department of Health and Nutrition, School of Home Economics, Wayo Women’s University, Chiba 272-8533, Japan. ³Laboratory of Physiological Nutrition, Kagawa Nutrition University, Saitama 350-0288, Japan. ⁴Department of Nutrition, Chiba Prefectural University of Health Science, Chiba 261-0014, Japan. ⁵Department of Food Science and Nutrition, School of Agriculture, Kinki University, Nara 631-8505,Japan. ⁶Department of Health and Nutrition Science, Faculty of Health and Social Welfare Science, Nishikyushu University, Saga 842-8585, Japan. ⁷Department of Health and Nutrition, Faculty of Human Life Studies, University of Niigata Prefecture, Niigata 950-8680, Japan. ⁸Department of Nutrition, Mie Chukyo University Junior College, Mie 515-8511, Japan. ⁹Laboratories of Food Science and Nutrition, Department of Life Style Studies, School of Human Cultures, The University of Shiga Prefecture, Shiga 522-8533, Japan. ¹⁰Graduate School of Human Life Science, Mimasaka University, Okayama 708-8511, Japan. ¹¹Department of Human Environmental Science, Fukuoka Women’s University, Fukuoka 813-8529,Japan. ¹²Graduate School of Science for Living System, Showa Women’s University, Tokyo 154-8533,Japan. ¹³Department of Health and Nutrition, Faculty of Human Sciences, Hokkaido Bunkyo University, Hokkaido 061-1449, Japan.

Abstract

Recent evidence suggests that voluntary rhythmic movements such as chewing may increase blood serotonin and subsequently brain serotonin, which in turn acts to alleviate premenstrual symptoms. In this observational cross-sectional study, we tested the hypothesis that hardness (difficulty of chewing) of the habitual diet (i.e. dietary hardness) is associated with decreased premenstrual symptoms. Subjects were 640 female Japanese dietetic students aged 18–22 years. Dietary hardness was assessed as an estimate of masticatory muscle activity for the habitual diet (i.e. the difficulty of chewing the food). The consumption of a total of 107 foods was estimated by means of a self-administered, comprehensive diet history questionnaire, and masticatory muscle activity during the ingestion of these foods was estimated according to published equations. Menstrual cycle symptoms were assessed using the retrospective version of the Moos Menstrual Distress Questionnaire, from which total score and subscale scores (i.e. pain, concentration, behavioral change, autonomic reactions, water retention, and negative affect) in the premenstrual phase were calculated and expressed as percentages relative to those in the intermenstrual phase. Dietary hardness was not associated with total score in the premenstrual phase (P for trend = 0.48). Further, no association was seen for any subscale score in the premenstrual phase (P for trend = 0.18–0.91). In conclusion, this preliminary study failed to substantiate a hypothesized inverse relationship between hardness of the habitual diet and premenstrual symptoms. Considering the plausibility of the putative mechanism, however, further investigation using more relevant measures of chewing and premenstrual symptoms is warranted.