A nocturnal lifestyle is now common due to changes in the social environment. The aim of this study was to clarify the influence of eating rhythm on diet-induced thermogenesis (DIT). For 33 healthy female volunteers (aged 20.5±1.2 y) who were non-smokers, we established two meal patterns, one (morning) in which the participants ate meals at 07:00, 13:00, and 19:00, and another (night) in which they ate at 13:00, 19:00, and 01:00. The energy of each meal was 500 kcal. DIT was evaluated by measuring the energy consumption after each meal using a cross-over design. DIT at 07:00 was the highest among the three meals for the morning pattern (p<0.05), and DIT at 01:00 was the lowest among the night pattern meals by a significant margin (p<0.01). The total accumulation of DIT was also significantly lower for the night pattern than for the morning pattern (p<0.01). These results indicate that the habit of eating at night without taking breakfast may be one of the reasons for obesity, because the decrease in energy consumption during the day depends on falling DIT.

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This study examined the effect of dietary lard and fish-oil intake by rats during pregnancy and lactation on the composition of the stomach contents and plasma lipid concentration in pups. Two groups of dams were fed a lard diet (LD) and a fish-oil diet (FD) during pregnancy and lactation; all pups were fed the same diets as the dams until weaning. No significant difference in body weight was observed between the two groups of dams and their pups. However, the plasma triacylglycerol concentration in dams fed FD was lower than that in dams fed LD. Although there was no significant difference in the protein (P), fat (F) and carbohydrate (C) energy ratio of the stomach contents of pups between the two groups until weaning, the fatty acid compositions of the pups changed according to the fatty acid compositions of the diets given to the dams, and the n-6/n-3 ratio in the stomach contents of the LD group and FD group were 18.6 and 1.5, respectively. The FD group had a lower ratio than the LD group, although the plasma triacylglycerol concentration and total cholesterol concentration in the pups decreased with the progress of weaning. Perirenal fat tissue in pups of the FD group was lower than that in pups of the LD group. Therefore, the fatty acid compositions of the stomach contents of pups changed in accordance with the dams’ fat intake. In addition, the plasma lipid concentration and the body composition of pups were influenced accordingly. These results suggest that fish oil intake during pregnancy lowers the plasma lipid concentration of both dams and pups.

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The aims of this study were to develop an ultraviolet (UV) radiation-based micronucleus assay for measurement of oxidative DNA damage levels and to examine its applicability to nutrition research. WIL2-NS cells were exposed to UV radiation, and the frequency of micronucleated cells was determined as an indicator of oxidative DNA damage. UVA radiation at 420 μW/cm² did not significantly increase the number of micronucleated cells, whereas UVB radiation at 300 μW/cm² for 0-5 s induced an increase in the count of micronucleated cells that was proportional to the period of exposure. Similar results were obtained when WIL2-NS cells were substituted with human lymphocytes, indicating that UVB radiation can be applied to the micronucleus assay. Furthermore, analysis of blood samples collected from female high school students demonstrated a significant negative correlation between the blood β-carotene level and frequency of UV-induced micronucleus formation (r=−0.443, p<0.05). These observations suggest that UVB-enhanced oxidative damage can be used for evaluating the antioxidant properties of certain nutrients such as β-carotene.

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