Treatment of natto, a fermented soybean preparation, to prevent excessive plasma vitamin K concentrations in patients taking warfarin.

The purpose of this study is to find a method of cooking natto that prevents the appearance of high-plasma vitamin K concentrations after the consumption of natto, so that patients taking warfarin can benefit from eating natto. Five cooking methods were examined to determine which could most effectively decrease the count of the living Bacillus subtilis in natto. Volunteers ate natto or treated natto, and their plasma vitamin K level was measured at 5, 8, 24 and 48 h thereafter. One gram of natto contained 9.7+/-0.1 Log cfu/mL of Bacillus subtilis. Boiling significantly reduced the Bacillus subtilis count to 5.1+/-0.3 Log cfu/mL, and concomitantly reduced the content of menaquinone-7 (MK-7), which is a form of vitamin K synthesized by Bacillus subtilis, from 660.40+/-65.32 ng/mL to 78.50+/- 11.12 ng/mL. Untreated natto increased the MK-7 concentration in blood from 1.86+/-1.51 ng/mL to 14.54+/-4.12 ng/mL at 5 h after intake, and the MK-7 concentration remained elevated at 8, 24 and 48 h (7.29+/-2.20, 6.97+/-2.60, and 5.37+/-1.94 ng/mL, respectively). In contrast, boiled natto increased plasma MK-7 only mildly (from 1.61+/-1.11 to 4.02+/-0.82 ng/ mL at 5 h) and the concentration remained relatively stable up to 48 h (3.46+/-0.83, 4.22+/-1.51 and 2.77+/-0.75 ng/mL at 8, 24 and 48 h, respectively). In conclusion, boiled natto did not cause a marked increase in the plasma concentration of vitamin K in subjects who consumed it. Thus, patients on warfarin may be able to eat boiled natto without ill effects.

Lower energy content of human milk than calculated using conversion factors.

BACKGROUND: Bodyweight gain of formula-fed babies is usually higher than that of breast-fed ones. The energy content of human milk is usually quantified not by direct measurement but by calculation based on The Standard Tables of Food Composition in Japan. For this study, the energy of human milk was quantified in two ways, using a direct measurement and a calculation method. METHODS: A total of 227 milk samples (192 colostrum, 21 transitional milk, and 14 mature milk) were collected from 114 healthy women. Energy of the whole milk was measured by ballistic bomb calorimetry. The content of protein, fat, and carbohydrate was determined by direct measurement methods. Energy of the milk was also calculated according to the indices in The Standard Tables. RESULTS: The mean value for all milk samples of directly measured energy was significantly lower than that of the calculated energy (58.1 +/- 8.1 vs. 64.5 +/- 10.6 kcal/100 g, n = 227, P < 0.05). Similar results were observed in colostrum and transitional milk but not in mature milk. Measured energy in mature milk was significantly higher than that in colostrum (64.2 +/- 3.6 vs. 57.1 +/- 8.0 kcal/100 g, P < 0.05). Protein concentration in mature milk was significantly lower than that in colostrum (1.4 +/- 0.4 vs. 2.2 +/- 0.7 g/100 g, P < 0.05). CONCLUSIONS: The measured energy content of human milk was lower than the calculated energy based upon the Standard Tables, suggesting that formula milk contains excessive energy.