2.5. Experimental Food and Study Settings
Flaxseed oil was provided by NIPPN Corporation (Tokyo, Japan), and corn oil was purchased from J-OIL MILLS, Inc. (Tokyo, Japan), and both were individually packed without any labels. The packages were completely identical in color, shape, and size between the test foods. Compliance was monitored by having the subjects mark the calendar provided by the test center whenever the test food was consumed and asking them to bring the calendar with them when they visited the study center for assessments during the experimental period (pre-, after 6 and 12 weeks of intervention). Subjects were asked not to change their daily habits, including physical activity, diets, and daily behavior during the experimental period, and were free to take medications. Dietary habits were checked using the validated food frequency questionnaire (FFQg Ver. 5) [