Corn oil

Fish oil DHA-46 and GNO were provided by Tama Biochemical Co., Ltd. (Tokyo, Japan) and NPO Arcoiris Naturaleza (Matsudo, Chiba, Japan), respectively. Corn oil was purchased from Oriental Yeast Co., Ltd. (Tokyo, Japan). LC/MS grade methanol, 2-propanol, and ultrapure water were purchased from Wako Pure Chemical Industries (Osaka, Japan). OA, lysophosphatidylcholine (18:1), phosphatidylcholine (18:1/18:1), DHA, phosphatidylcholine (22:6/22:6), and sodium formate were purchased from Sigma-Aldrich (St. Louis, MO, USA). AA was purchased from Cayman Chemical (Ann Arbor, Michigan, MI, USA).

Male C57BL/6J mice (9 weeks old) were obtained from Clea Japan (Tokyo, Japan), and maintained at 23 ± 2°C under a 12:12 h light–dark cycle (lights on from 7.00am to 7.00pm). The mice were individually housed in plastic cages and fed a laboratory diet (CE-2; Clea Japan) for 1 week to acclimatize them to the metabolic conditions.
WB was purchased from Nisshin Pharma (Wheat bran DF; Tokyo, Japan). The WB was steamed using a twin screw extruder (EA-20; Suehiro EPM Corp., Mie, Japan) and termed ‘steamed WB’. The nutritional content of the steamed WB is shown in Table 1. Milk casein, corn oil, cellulose, AIN-76 mineral mixture, AIN-76 vitamin mixture, and gelatinized potato starch were purchased from Oriental Yeast Co. (Tokyo, Japan), and sucrose was purchased from Wako Pure Chemical Industries (Osaka, Japan). Lignin was purchased from Kanto Chemical Co. (Tokyo, Japan).Table 1.

Nutritional content of steamed wheat bran.

Component	Content (%)
Protein	18.9
Fat	4.2
Carbohydrate	20.2
Dietary fiber	47.9
Moisture	2.3
Ash	6.5

After the surgery, the rats were fed either a standard (control) diet or an EqD. The standard diet was a modified pellet-formed AIN-93M diet in which soybean oil was replaced with corn oil (Oriental Yeast, Osaka, Japan). The EqD was a diet in which S-equol-containing SE5-OH (Otsuka Pharmaceutical, Tokyo, Japan) was added to the standard diet. The protein and lipid contents of the EqD were adjusted to values equivalent to those of the standard diet (Table 1). SE5-OH was developed by the fermentation of soy germ by the S-equol-producing lactic acid bacterium Lactococcus strain 20-92. The major characteristics of SE5-OH are the relatively high content of S-equol (0.5–0.6%) as an isoflavonoid (total isoflavonoid content is approximately less than 1%) and the low genistein content (33 (link)). The EqD contained 138.7 mg/kg S-equol and 14.0 mg/kg genistein. The contents of isoflavones and metabolites in SE5-OH and EqD are shown in Table S1 in Supplementary Material.