Metabolic response to short-term 4-day energy restriction in a controlled study.

OBJECTIVES: Metabolic rate is affected not solely by diet but also by environmental characteristics such as climate and seasonal changes in day length. In the present study, we conducted a controlled study in which we observed metabolic response to short-term energy restriction (ER). MATERIALS AND METHODS: Thirty-two subjects were divided randomly into a slight ER group and a moderate ER group. The energy intake per day for slight ER vs moderate ER was 1462 kcal vs 1114 kcal. During the 4-day study periods, the same daily timetable, which consists of nutrition, exercise, sleeping and others, was imposed on both groups. The same environment was also provided to both groups. RESULTS: After the 4-day ER, significant decreases in body weight and basal metabolic rate (BMR) were shown in both groups. The decrease in body weight was 2% of the baseline level in both groups, and the decreases in the BMR were 6% of baseline levels in the slight ER group and 13% in the moderate ER group. The decrease in BMR in the moderate ER group was significantly larger than that in the slight ER group. CONCLUSIONS: In a controlled study of short-term ER, we observed a significant decrease in BMR. There was a positive association between the degree of ER and the reduction in BMR. Reductions in BMR were greater than those in body weight. It, thus, appears that the minimization of weight loss is due to dramatic decreases in BMR. This suggests the existence of metabolic resistance against ER.

Liver cancer risk in Japanese male dentists: a long-term retrospective cohort study.

It has been speculated that dentists are at high risk for occupational exposure to bloodborne viruses such as hepatitis B and hepatitis C viruses. To assess the risk of the development of liver cancer among Japanese male dentists, we conducted a retrospective cohort study on 3,314 dentists of the Osaka Dental Association who were members between 1964 and 1985, the year before HBV immunization became available. By linking to the Osaka Cancer Registry, we found that during the period of 1964-1997, 36 of the dentists were diagnosed with liver cancer over a mean follow-up of 23.6 yr. The observed number of liver cancer cases was compared with the expected number, which was calculated by multiplying the number of person-years at risk by the corresponding age- and calendar time-specific incidence rate from the Osaka Cancer Registry data. The male dentists had a significantly lower risk of developing liver cancer than the general population of Osaka (O/E=0.71, 95% CI=0.50-0.98). On subcategorical analysis by birth year or duration of follow-up, there was no significantly increased risk of developing liver cancer among the dentists. Contrary to our expectation, our findings indicate that Japanese dentists were not at increased risk of developing liver cancer compared with the general population.

Trends in levels of cholesterol in Japanese children from 1993 through 2001.

BACKGROUND: Cardiovascular risk factors in children raise the possibility of cardiovascular disease later in life. We attempted to determine the current trends in cardiovascular risk factors among Japanese children. METHODS: We examined fifth-graders at all the elementary schools in Iwata city in Japan every year from 1993 through 2001. We examined 4,673 boys and 4,484 girls, aged 10-11 years. Height, body weight, body mass index, and serum total cholesterol concentrations were measured. Regression analysis was used to evaluate the trends. The independent variable was the calendar year of the examination. The dependent variables were the anthropometric values and the serum total cholesterol concentration in each individual. The relationships between the year and the prevalence of hyperlipidemia and the prevalence of obesity were also examined. RESULTS: Both the heights of the girls and the body weights of the both sexes were positively associated with the year. The body mass index in both girls and boys also showed positive relationships with the calendar year. In addition, there was an increase in the prevalence of obesity. Concerning the levels of cholesterol, positive regression coefficients were shown between the total cholesterol concentration and the year in both sexes. Furthermore, there was an increase in prevalence of hyperlipidemia. CONCLUSION: These results indicate that during the past decade among Japanese children involved in the study, both the body mass index and the serum total cholesterol concentrations increased.

Dietary restriction: effects of short-term fasting on protein uptake and cell death/proliferation in the rat liver.

Dietary restriction (DR) is known to prolong life in laboratory animals. Intermittent (alternate-day) fasting or short-term repeated fasting has also been reported to increase the life span of animals. In the present study, we investigated the changes or induction of abnormalities of protein metabolism in rats during fasting, and measured asialoglycoprotein uptake and cell death/proliferation in the liver of rats receiving fasting and refeeding. In the results, liver weight decreased significantly after 48 h of fasting and increased during the refeeding period, returning to the pre-fasting level by 12 h of refeeding. Cell death, determined by single stranded DNA (ssDNA) staining method, increased during the fasting period, and returned to the pre-fasting level during the refeeding period. Cell proliferation, determined using antibodies (Ab) against proliferating cell nuclear antigen, decreased during the fasting period, and increased during the refeeding period. Changes in cell death and cell proliferation were inversely related. However, there was no significant difference in asialoglycoprotein uptake by the whole liver between the ad libitum (AL)-fed rats and 48 h fasted rats. Thus, neither the changes in liver weight nor cell death/proliferation affected asialoglycoprotein uptake on a living body. These results suggest that episodes of 48 h fasting do not induce protein metabolism abnormalities in the liver.

Lung cancer risk in male dentists: a retrospective cohort study in Japan, 1964-1997.

It is reported that dentists are exposed to heavy metals in their clinics. To assess the risk of developing lung cancer among male Japanese dentists, we conducted a retrospective cohort study of 3,314 members of Osaka Dental Association (Osakafu-Shikaishikai). During 1964-1997, 39 were diagnosed with lung cancer, which figure was obtained from the file of the Osaka Cancer Registry. The observed number of lung cancers was compared with the expected number calculated by multiplying the number of person-years at risk by the corresponding age- and calendar time-specific incidence rate from the Osaka Cancer Registry data. The male dentists had no significantly different risk than general population.(O/E=1.01, 95%CI=0.72-1.39). Contrary to expectation, these findings indicate that Japanese dentists had almost the same overall risk of developing lung cancer as the general population.

Suppressive effects on delayed type hypersensitivity by fasting and dietary restriction in ICR mice.

Dietary restriction improves declining physiologic functions, prevents or lessens the severity of neoplasms and autoimmune diseases, and attenuates various inflammatory reactions. In the present study, we compared the effect on allergic dermatitis from repeated short-term fasting (every 3 days), and from moderate dietary restriction receiving 60% of the amount of food consumed by an ad libitum feeding group. In addition, we attempted to verify the involvement of corticosteroids and oxidative stress during nutritional deprivation. The overall food intake in mice undergoing moderate dietary restriction was less than that in mice undergoing repeated fasting. Nonetheless, moderate dietary restriction and repeated fasting showed similar suppressive effects on dermatitis. Furthermore, both the restricted-diet and fasted mice showed less oxidative stress than the mice fed ad libitum. In RU486 (a glucocorticoid receptor antagonist)-injected mice, no suppressive effect of fasting on dermatitis was seen. In conclusion, repeated fasting and moderate dietary restriction suppressed dermatitis in similar ways. Hypercorticism and reduced oxidative stress is associated with the suppression of dermatitis.

An adult with atopic dermatitis and repeated short-term fasting.

It has been reported that nutritional stress, such as short-term fasting and long-term energy restriction, has a suppressive effect on allergic dermatitis in experimental animals. Furthermore, clinical study has demonstrated a positive association between weight loss by low-energy diet and improvement in patients with atopic dermatitis. In this report, a 23-year-old female with atopic dermatitis received a treatment of repeated short-term fasting. 24-hour fasting was conducted once a week for a period of 20 weeks. On the fasting day, the amount of energy intake was 200 kcal. No medication was administered during the trial period. Clinical symptoms were evaluated using the Scoring Atopic Dermatitis index, and IgE, lactase dehydrogenase-5, and number of eosinophils were measured. At the end of the trial, body weight was reduced and clinical symptoms improved, whereas no improvements in laboratory findings were shown. For sufficient evidence of the effects of fasting, additional controlled study is needed.