• Journal of Nutrition and Health
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• v.36 no.7
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• pp.736-742
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• 2003

Soybeans have been a major protein source for many centuries in Korea. Soybeans contain phytochemicals which are isoflavones, biochemically active component. Isoflavone is a kind of phytoestrogen, structurally and functionally similar to estrogen. It has been reported that the breast milk and blood of breast feeding mothers who consume soy products contain isoflavones. This study was conducted to investigate the effects of soy milk supplement on the isoflavones (daidzein, genistein) concentration of breast milk, plasma and urine from breast feeding woman. Seventeen healthy women who delivered at Kyung Hee Medical Center were recruited. For the first 2 weeks after delivery, seventeen women ingested 400 ml (isoflavone 43.2 mg) of soy milk on the given time starting from the day of giving birth. For the next 2 weeks, soy milk ingestion was withdrawn. Dietary intake and anthropometric data were checked and breast milk, blood, and 24 hr urine samples were collected on the day of giving birth, the 14th (the last day of the supplement phase) and 28th (the last day of the withdrawal phase) day, respectively. HPLC analysis was used to measure the concentration of isoflavones. Dietary intakes of the subjects were inadequate for the Korean RDA regardless of soy milk supplementation. Especially, intakes of vit A, calcium, and iron were very low. The Anthropometric data such as LBM, TBW, PIBW, BMI checked on the day of 14th decreased and maintained their levels by the 28th day. Daidzein concentration in breast milk was not affected by soy milk supplementation. However, genistein concentration decreased by the 28th day (14th day: 0.89 $\pm$ 0.10 $\mu$g/ml, 28th day : 0.48 $\pm$ 0.07 $\mu$g/ml) (p < 0.05). Plasma daidzein and genistein concentrations were not changed by the 14th day and decreased by the 28th day (14th day: 49.64 $\pm$ 3.30 ng/ml, 26.72 $\pm$ 2.90 ng/ml, 28th day: 38.30 $\pm$ 4.40 ng/ml, 6.51 $\pm$ 0.50 ng/ml, respectively) (p < 0.05). Twenty four hour urine concentrations of daidzein and genistein significantly increased by the 14th day and decreased by the 28th day (14th day: 5.80 :t 0.3 mg/d, 4.17 $\pm$ 0.2 mg/d, 28th day: 6.72 $\pm$ 0.4 mg/d, 5.09 $\pm$ 0.5 mg/d, respectively) (p < 0.001). The rate of urinary recovery of daidzein was greater than that of genistein. The results of this study indicate that the supplement of dietary soy milk to the lactating women elevates the contents of isoflavone in the breast milk.

• Nutrition Research and Practice
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• v.1 no.3
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• pp.206-211
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• 2007

This study estimated the isoflavone intake level in Koreans using Food Frequency Questionnaire and analyzed related variables. The results showed that the average daily intake of isoflavone in adults was shown as 23.1 mg. The isoflavone intake level at 50 percentile was 16.9 mg ($0{\sim}90\;mg$), and 10% of adults took almost 50 mg of isoflavone a day and 10% took about 5 mg a day. The major food sources for isoflavone in Koreans were in the order of soybean, soybean paste, soy milk, soybean curd (tofu), and bean sprouts; the intake was different depending on age, educational background, occupation, economic standard, and family type. The result showed higher isoflavone intake levels in the group over 30 years old and the highest isoflavone intake in subjects working in farming/fishery, followed by housemakers. According to the differences by families the families with elderly members showed 50% higher isoflavone intake than young families with friends or siblings. Depending on related ecological variables, therefore, various nutrition education programs should be developed for a variety of intakes of soybean foods, along with easy and simple cooking methods as parts of continuous research.

• Journal of Nutrition and Health
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• v.36 no.5
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• pp.452-458
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• 2003

Soybean is a rich source of isoflavones such as genistein and daidzein. Soy isoflavones have both weak estrogenic and anti-estrogenic effects and are structurally similar to tamoxifen, an agent that has an effect similar to that of estrogen in terms of reducing postmenopausal bone loss. The purpose of this study was to determine the effects of differences in protein source (casein vs soy) and isoflavone levels (reduced vs higher levels) on selected bone markers and hormones in growing male rats. Thirty weanling Sprague-Dawley young rats were divided into 3 groups: The control group was fed a casein-based diet, the soy concentrate group was fed soy protein with totally reduced isoflavones content (isoflavones 0.07 mg/g protein), and the soy isolate group was fed soy protein with a higher than normal isoflavones content (isoflavones 3.4 mg/g protein). The degree of bone formation was estimated by measuring serum osteocalcin and alkaline phosphoatase (ALP). By determining collagen cross-linkage by immunoassay and correcting with creatinine values, the bone resorption rate was compared. Serum osteocalcin, growth hormone, estrogen and calcitonin were analyzed using radio immunoassay kits. The bone formation marker and ALP activity were differentiated by protein source, showing higher values than casein in feeding either soy isolate or soy concentrate. In this study using growing rats, the differences in isoflavone contents were not a significant factor in either bone formation or bone reaborption markers. Moreover, the soy isolate group had significantly higher levels of growth hormone than the casein group. The findings of this study suggest that growth hormone is partially responsible for its bone-formation effects in young growing rats. Soy protein and the isoflavones in soy protein are beneficial for bone-formation in growing male rats. Therefore, exposure to soy protein and isoflavones early in life may have long-term health benefits in preventing bone diseases such as osteoporosis. Further study to evaluate the mechanism of action of isoflavones on bones is warranted. (Korean J Nutrition 36(5): 452∼458, 2003)

• Journal of Nutrition and Health
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• v.37 no.1
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• pp.45-51
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• 2004

In this study, isoflavone (genistein, genistin, daidzein, daidzin) contents in various parts of twelve soybean cultivars and three soy sprouts were determined by high performance liquid chromatography with UV detector. Three cultivars of soybean were selected and cultured in the lab to produce sprout for five days. Total isoflavone (Total IF) varied greatly among differnt breeds of soybean in range of 99 - 649.9 $\mu\textrm{g}$/g and 522.3 - 1,277.7 $\mu\textrm{g}$/g respectively, domestic and foreign cultivars. There were greatly difference in total IF of various parts of the soybean sprouts. Sprout from the Myunjunamul-kong appeared to have 69% genistein and 22% genistin in head part, and 30% and 62% of daidzin and daidzein, respectively, in root. Meanwhile, the sprouts from Junjori contains most (84%) of daidzein in its root. Sprout from chinese black-soybean had the largest amount of genistein among the sprouts but, there were no differences in the average genistein content between three selected black and non-black soys. The glycosidic form of IF were dominant compared to aglycone forms both in soybean and sprouts by 24 times and 12 times, respectively, suggesting that during the sprouts cultivation glycosidic forms could change to aglycone forms. There are no difference in total content between genistein + genistin and daidzein + daidzin in soy and soy sprout. Therfore, considering the total IF contents, the intake of 1 soy sprout is similer to 1.5 times as soybean.

• Journal of Nutrition and Health
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• v.38 no.5
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• pp.335-343
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• 2005

Rodent models have been used to study the anticarcinogenic properties of the soy isoflavones, particularly genistein, but there is little information regarding the pharmacokinetics of the absorption and excretion of genistein. In this study, rats were given a single oral dose of genistein (20 mg/kg body wt) or an equivalent dose as Myougjoonamul-kong and Myoungjoonamul soy sprouts. Concentrations of genistein were measured in plasma, urine and feces at intervals up to 48hr after dosing. Maximum peak of plasma genistein concentration is 8 hr after dosing, and its concentration is 13.2, 7.4mol/L in soy and soy sprout-treated rats, respectively. In pure genistein treated rats, maximum peak of plasma genistein concentration is 2hr after dosing (5.7 mol/L). The percentage of dose recovered in urine over 48hr was not different between groups ($21.2\%$ soy treated; $18.2\%$ soy sprout treated; $16.1\%$ pure genistein treated). There were no significant differences between groups in the recovery of genistein in feces ($19.5\%,\;7.5\%\;and\;15.7\%$ of doses, respectively). $6.9\%\;and\;6.07\%$ of the daidzein from the soy and soy sprout treated was recovered in the feces.

• Journal of Nutrition and Health
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• v.39 no.8
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• pp.801-807
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• 2006

To elucidate the effect of soy isoflavone supplementation on bone mineral density and antioxidant enzyme activity in 60 postmenopausal women residing in Iksan area were recruited. There were 31 participants in the treatment group and 29 in the control group. The treatment group consumed isoflavone extract capsules daily (which contained 90 mg of soy isoflavones) for 12 weeks. The study compared before and after isoflavone intake in the following areas. Physical examination, diet survey, bone mineral density (BMD) and antioxidant enzyme activity (superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and total antioxidant capacity (TA)). The average age of the treatment group was 64.6 years and that of the control group was 66.5 years. There were no significant differences between the two groups in terms of height, weight and body mass index. Both groups maintained a regular diet pattern in terms of their average daily nutrient intake. There were no significant differences between the treatment group (23.3 mg) and the control group (24.0 mg) in terms of daily isoflavone intake based on diet. Isoflavone supplementation of 12 weeks did not resulted in any significant changes in BMD or parameters of antioxidant enzyme activity, implying the necessity of more intensive intervention for a substantial change. In conclusion, this study revealed that antioxidant enzyme activity holds a significant relationship with the bone mineral density in postmenopausal women and further systematic research on dose and period of isoflavone supplementation is needed to clearify the positive effect of isoflavone on BMD and/or blood antioxidant capacity in postmenopausal women.

• Journal of Nutrition and Health
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• v.34 no.3
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• pp.322-329
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• 2001

There is growing evidence that soy isoflavones play beneficial role in the prevention of cardiovascular disease. However, current data are not sufficient to determine the effective dose of isoflavone on improving plasma lipid profiles and total antioxidant capacity in Korean menopausal women. In the present study, 24 perimenopausal and 23 postmenopausal women were divided into 3 groups and were given soy isoflavone supplements of 100, 150, 200mg/day for 12weeks. Blood samples were taken before and after 6, 12weeks of soy isoflavone supplementation for analysis of total cholesterol, LDL cholesterol, HDL cholesterol, triglyceride and total antioxidant status(TAS). In the perimenopausal women, serum total cholesterol level decreased significantly in all three groups after 12weeks of isoflavone supplementation(p< 0.05). However, serum LDL cholesterol level significantly lowered only in 150 and 200mg groups, and serum triglyceride level decreased significantly in 200mg group(p<0.05). In the postmenopausal women, the 150mg isoflavone supplementation group demonstrated significant effects on lowering serum total cholesterol, LDL cholesterol levels and raising HDL cholesterol level after 12weeks of isoflavone supplementation(p<0.05). Two hundred mg isoflavone supplementation group had a significantly higher TAS than other groups in both perimenopausal and postmenopausal women. (Korean J Nutrition 34(3) : 322∼329, 2001)

• Journal of Nutrition and Health
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• v.39 no.3
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• pp.219-224
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• 2006

This study was performed to determine the effect of soy isoflavones on brain development and function in rats. Forty Sprague-Dawley male rats were provided diets containing different levels of soy isoflavones for 6 weeks; 0 ppm (control), 50 ppm (low isoflavone intake; LI), 250 ppm (medium isoflavone intake; MI) and 500 ppm (high isoflavone intake; HI). Learning ability was evaluated by a Y-shaped water maze and the activity of acetylcholinesterase in brain was assayed after decapitation. Food intake and body weights as well as weights of brain, liver, spleen, heart and kidney showed no significant difference among the four groups, which means 500 ppm of isoflavones is safe. In the water maze test, the frequency of error counted when rats entered one end of the alley without platform was significantly lower in the HI group than in the control group, and the escape latency as swim time taken to escape on the hidden platform was significantly shorter in the HI group than in the LI and control groups. The activity of acetylcholinesterase of the brain was significantly higher in the HI and MI groups than in the control group. Therefore, the results indicate that isoflavones may improve the cognitive function without adverse effects.

• The Korean Journal of Food And Nutrition
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• v.19 no.4
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• pp.460-465
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• 2006

This study was conducted to investigate the isoflavone contents including daidzein and genistein in soy sauces made with whole grain soybean Meju(WGSM), comparing with defatted Meju(DM) du.ins fermentation. Total isoflavone contents in 2 soy sauces made with DM, Control and product A, increased with period of fermentation and were 15 and 4.3 times higher after 180 days of fermentation than on the day before fermentation respectively. Meanwhile, 2 soy sauces made with WGSM, product B and C, had the highest amounts with $20.53{\mu}g/g\;and\;19.52{\mu}g/g$ of isoflavones on the day before fermentation respectively, and then decreased with fermentation time. High amounts of isoflavones were detected in 20 days of fermentation of soy sauce which made with WGSM and wheat Meju(product D). Daidzein was the largest amounts in isoflavone contents, regardless of total or free isoflavone types. The level of daidzein increased with fermentation time in 2 soy sauces made with DM, Control and product A, whereas 2 soy sauces made with WGSM, product B and C decreased with fermentation time, instead of increasing of genistein contents.

• Nutritional Sciences
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• v.7 no.1
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• pp.17-22
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• 2004

This study was undertaken to determine the bioavailability of isoflavones in weanling Sprague-Dawley rats by providing diets containing different levels of soy isoflavones for 6 weeks: 0.025% (low isoflavone intake; LI), 0.125% (medium isoflavone intake; MI), and 0.25% (high isoflavone intake; HI). The subsequent fecal and urinary excretion of daidzein and genistein was then measured. As the levels of dietary isoflavones increased, the amount of food intakes significantly decreased, and weight gain was slower in female rats. In male rats, there was no significant difference in weight gains related to dietary intakes. Urinary excretion of daidzein and genistein was significantly higher in the MI and HI groups in both male and female rats than the control and LI groups. The recovery % of daidzein and genistein in the urine was significantly lower in the MI and HI groups. Fecal daidzein increased as dietary isoflavone intakes increased in female rats; however, in male rats the increase was significant only in the HI group. The recovery % of daidzein and genistein in the feces of female rats was not significantly different among the four groups. When dietary isoflavones were increased from 0.025% to 0.25%, the amounts of daidzein and genistein excreted in the urine and feces increased; however, the low recovery rate of both daidzein and genistein in the urine implies an increased bioavailability of isoflavones. We also observed sex-related differences in the urinary and fecal recovery of isoflavone intakes.