Life Sci. 2014 May 8;103(1):8-14. doi: 10.1016/j.lfs.2014.03.022.

Long-term feeding on powdered food causes hyperglycemia and signs of systemic illness in mice.

Tsuchiya M1, Niijima-Yaoita F2, Yoneda H3, Chiba K4, Tsuchiya S5, Hagiwara Y5, Sasaki K3, Sugawara S6, Endo Y6, Tan-No K2, Watanabe M4.

  • 1Divisions of Aging and Geriatric Dentistry, Tohoku University, Sendai 980-8575, Japan. Electronic address:
  • 2Department of Pharmacology, Tohoku Pharmaceutical University, Sendai 981-8558, Japan.
  • 3Advanced Prosthetic Dentistry, Tohoku University, Sendai 980-8575, Japan.
  • 4Divisions of Aging and Geriatric Dentistry, Tohoku University, Sendai 980-8575, Japan.
  • 5Oral Dysfunction Science, Tohoku University, Sendai 980-8575, Japan; Department of Orthopaedic Surgery, Graduate School of Medicine, Tohoku University, Sendai 980-8575, Japan.
  • 6Oral Immunology, Graduate School of Dentistry, Tohoku University, Sendai 980-8575, Japan.



AIMS: Dietary habits are crucial factors affecting metabolic homeostasis. However, few animal experiments have addressed the effects of long-term feeding with soft food on parameters reflecting systemic health.

MAIN METHODS: Using mice, we compared the effects of short (3 days) and long (17 weeks from weaning) feeding periods between powdered food and normal pellet food on the levels of blood glucose, serum levels of insulin, catecholamines, and corticosterone, blood pressure, and/or social interaction behaviors. In addition, the effects of a human glucagon-like peptide-1 analog, liraglutide (a new drug with protective effects against neuronal and cardiovascular diseases), were compared between the powder and pellet groups.

KEY FINDING: (i) Powdered food, even for such a short period, resulted in a greater glycemic response than pellet food, consistent with powdered food being more easily digested and absorbed. (ii) Long-term feeding on powdered food induced hyperglycemia and related systemic signs of illness, including increases in serum adrenaline, noradrenaline, and corticosterone, higher blood pressures (especially diastolic), and increased social interaction behaviors. (iii) Liraglutide, when administered subcutaneously for the last 2 weeks of the 17-week period of feeding, improved these changes (including those in social interaction behaviors).

SIGNIFICANCE: The hyperglycemia associated with long-term powdered-food feeding may lead to certain systemic illness signs, such as elevations of blood glucose, hypertension, and abnormal behaviors in mice. Mastication of food of adequate hardness may be very important for the maintenance of systemic (physical and mental) health, possibly via reduction in the levels of blood glucose and/or adrenal stress hormones (catecholamines and glucocorticoids). Copyright © 2014 Elsevier Inc.

KEYWORDS: Dietary habit; Glycemic homeostasis; Mastication

PMID: 24690390



Diet is important for the maintenance of our physical well-being. However, various problems associated with dietary habits such as eating excessively, fast food, soft food, and hyperglycemic food, are now commonplace worldwide. Mastication during eating has several good effects on the systemic, mental, and physical functions of the body. For example, harder diets involve an anti-diabetic action, and biting when in distressed conditions could decrease excessive physiological responses.

Eating no-chew foods such as those in liquid or powder form temporarily leads to greater glycemic and insulin responses in humans because of the higher digestible and absorbable content of the foods. The effect of a powder-only diet on health remains to be clarified. We discovered that mice fed with powdered food for 4 months had increased glucose levels and blood pressure, as well as adrenal stress hormones (e.g., adrenaline and corticosterone), compared with control mice (Fig. 1). Even if the ingredients of the food given to each of the two groups were the same and differed only in the mastication process required, still the two groups had notable differences.

Next, considering that the blood glucose dynamics in diabetic patients affects their emotion and/or mood, we performed emotional behavioral tests (spontaneous locomotor activity and social interaction tests) using the same mice. It is interesting that the mice in the powder group showed hyperactivity and excessive meddling with others (Niijima et al., 2013). The no-chewing dietary habit may cause not only glycemic disorders but also emotional and behavioral disorders. Highly glycemic conditions (or rapid dynamics of blood glucose before/after eating) might affect brain functions such as mood and emotion, especially in childhood, when physical and psychosocial developments are moat remarkable. The etiology of attention-deficit hyperactivity disorder (ADHD), the most common neurodevelopmental disorder of childhood, reportedly includes the issue of eating habits. We speculate that glycemic problems would deteriorate the symptoms of ADHD.

Finally, to investigate whether the problems encountered in mice fed with powdered diet over a long period are caused by hyperglycemic conditions, the mice were given liraglutide, a medicine used in type 2 diabetes patients with hyperglycemia. The results indicated that prevention of hyperglycemia mostly improved the symptoms of lifestyle-related diseases (or pre-disease conditions), increased blood pressure and corticosterone level, and induced behavioral changes. In the glycemic load theory, ingesting small, rather than large, food particles results in a greater glycemic response (i.e., increase in blood glucose level), and a diet with a high glycemic index would be harmful not only for metabolic patients but also for people at high risk of developing obesity-associated diseases.

Chewing dysfunction was reported to be a risk factor for diabetes. Our results suggest that the dietary habits of patients are as important as the nutritional dietary information that they receive. Diet therapy is critically important in the management of diabetes. Meanwhile, chewing ability is often neglected in the care of diabetic patients. Considering that people who are losing their teeth tends to prefer a soft diet, patients with chewing dysfunctions such as edentulous patients could not properly undergo diet therapy. With decreased chewing function, dental care, including implants, should be an effective choice compared with simple medication management. Meanwhile, in bedridden persons fed with a liquid diet only, such as gastrostomy patients, chewing is mostly impossible. For these patients, food with low glycemic load and adequate fat/protein contents might be better. We strongly hope for developments in nutritional science toward the care of such patients.

Problems on dietary habits noticeably rebound directly to physical and psychological health. Nevertheless, the availability of no-chew foods/drinks with nutritional information has become widespread. Only humans chew their food and appreciate soft food. Similarly, rodents seem to prefer soft food (Sako et al., 2004) because soft food could be eaten faster. Food intake is essential for survival and is an obvious myopic behavior among animals with higher intelligence. Psychological stress is generally classified as healthy (eustress), unhealthy, and chronic stress (distress). Among humans, chewing may be a eustressor in daily life.



  1. Niijima-Yaoita F, Tsuchiya M, Saito H, Nagasawa Y, Murai S, Arai Y, Nakagawasai O, Nemoto W, Tadano T, Tan-No K. 2013 Influence of a long-term powdered diet on the social interaction test and dopaminergic systems in mice. Neurochem Int. 63:309-15.
  2. Sako N, Ohashi R, Sakai N, Katsukawa H, Sugimura T. 2004 Conditioned food aversion elicited by the temperature of drinking water as a conditioned stimulus in rats. Physiol Behav. 83:93-8.

FigchewingFig 1. Chewing of food with adequate hardness may be very important for the maintenance of systemic (physical and mental) health, possibly via reduction in the levels of blood glucose and/or adrenal stress hormones.


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