Fibroblast growth factor-23 and phosphorus related factors in young Japanese women: a cross-sectional study.

Phosphorus homeostasis is determined by dietary intake, intestinal absorption, and renal tubular reabsorption of phosphorus. Serum fibroblast growth factor-23 (FGF-23) is considered to be a sensitive early biomarker of disordered phosphorus metabolism in both patients with chronic kidney diseases and healthy subjects. However, the number of studies evaluating serum FGF-23 concentrations in healthy subjects is limited. The objective of this cross-sectional study was to examine the relationship between serum FGF-23 concentrations and phosphorus related factors in 182 young Japanese women (mean age, 19.5±0.4 years). We found that higher serum concentrations of inorganic phosphorus and lower serum concentrations of 1,25-dihydroxy vitamin D as well as lower fat but higher phosphorus and calcium intake were weakly but significantly associated with high serum concentrations of FGF-23, adjusted for postmenarcheal age and body weight. These results suggested that in young Japanese women, serum FGF-23 might be indicative of phosphorus nutrition status. However, it is worthy of note that maturity factors, including postmenarcheal age and physical attributes, such as body weight, might be related to serum FGF-23 concentrations.

[Bone and Nutrition. Calcium intake and bone health].

Calcium is undoubtedly an essential nutrient. Many studies have confirmed a significant relationship between the intake of calcium, and bone quantity and density. With regard to Japanese dietary reference intake values, the reference calcium intake values have been determined while considering bone quantity. However, a correlation between calcium intake and bone fractures has not been established. In osteoporosis treatment and prevention guidelines, the recommended calcium preparation grade for osteoporosis treatment has been set at a low level. However, to ensure appropriate effectiveness of osteoporosis treatment, it is necessary to take an appropriate amount of calcium. In recent years, the calcium intake level for Japanese people has tended to decline, which emphasizes the need for taking an appropriate amount of calcium in the diet.

Dietary glycemic index, but not glycemic load, is positively associated with serum homocysteine concentration in free-living young Japanese women.

It has been suggested that diets which enhance diurnal insulin secretion, such as a high glycemic index (GI) and glycemic load (GL) diet, can be expected to increase homocysteine levels. We investigated the hypothesis that dietary GI and GL are positively associated with serum homocysteine concentration in a group of free-living young Japanese women. This preliminary cross-sectional study included 1050 female Japanese dietetic students aged 18 to 22 years. Dietary intake was assessed using a validated, self-administered, comprehensive diet history questionnaire. Fasting blood samples were collected and serum homocysteine concentrations were measured. Adjustment was made for survey year, region, municipality level, current smoking, current alcohol consumption, dietary supplement use, physical activity, body mass index, energy intake, and intakes of B vitamins (folate, vitamin B6, vitamin B12, and riboflavin). After adjustment for nondietary confounding factors, both dietary GI and GL were positively associated with homocysteine concentration (both P for trend=.001). The positive association between dietary GI and homocysteine concentration remained after further adjustment for intakes of B vitamins. Mean (95% confidence interval) values of serum homocysteine concentration for each quintile of dietary GI were 6.9 (6.7-7.2), 7.1 (6.8-7.3), 7.0 (6.7-7.2), 7.4 (7.2-7.7), and 7.3 (7.0-7.6) µmol/L, respectively (P for trend = .04). Conversely, there was no association between dietary GL and homocysteine concentration after further adjustment for intakes of B vitamins (P for trend = .40). To conclude, in a group of free-living young Japanese women, dietary GI, but not GL, was independently and positively associated with serum homocysteine concentration.

Serum adiponectin concentration in relation to macronutrient and food intake in young Japanese women.

OBJECTIVE: Little is known about the relation of modifiable dietary factors to circulating adiponectin concentrations, particularly in young adults and non-Western populations. The aim of this study was to determine the association between macronutrient and food intake and serum adiponectin concentration in a group of young Japanese women. METHODS: This cross-sectional study included 1047 female Japanese dietetic students aged 18 to 22 y. Using a validated, self-administered, comprehensive diet history questionnaire, we assessed intake of nutrients (protein, total fat, saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids, carbohydrates, and dietary fiber) and foods (rice, bread, noodles, potatoes, confectioneries, fats and oils, pulses, fish and shellfish, meats, eggs, dairy products, vegetables, fruits, coffee, green and oolong tea, black tea, and soft drinks) and glycemic index and load. Fasting blood samples were collected and serum adiponectin concentrations were measured. Adjustment was made for survey year, region, municipality level, current smoking, current alcohol drinking, physical activity, body mass index, energy intake, and intakes of other nutrients or foods. RESULTS: After adjustment for potential confounding factors, none of the nutrients examined was a significant determinant of serum adiponectin concentration. There was no association for glycemic index or load. Coffee was the only food significantly and independently associated with serum adiponectin concentration. Mean (SE) values of serum adiponectin concentration for each quartile of coffee intake were 12.4 (0.2), 12.4 (0.5), 12.5 (0.3), and 13.2 (0.3) µg/mL, respectively (P for trend = 0.04). CONCLUSION: In a group of young Japanese women, higher coffee intake was independently associated with higher serum adiponectin concentration.

Higher intake of vitamin B-6 and dairy products and lower intake of green and oolong tea are independently associated with lower serum homocysteine concentration in young Japanese women.

Little is known about the relation of modifiable dietary factors to circulating homocysteine concentrations, particularly in young adults and non-Western populations. We investigated the hypothesis that intakes of nutrients and foods are associated with serum homocysteine concentration in a group of young Japanese women. This cross-sectional study included 1050 female Japanese dietetic students aged 18 to 22 years. Dietary intake was assessed using a validated, self-administered, comprehensive diet history questionnaire. Fasting blood samples were collected, and serum homocysteine concentrations were measured. Adjustment was made for survey year, region, municipality level, current smoking, current alcohol drinking, dietary supplement use, physical activity, body mass index, energy intake, and intakes of other nutrients or foods. After adjustment for nondietary confounding factors, intakes of all B vitamins (folate, vitamin B-6, vitamin B-12, and riboflavin) were inversely associated with homocysteine concentration. However, only vitamin B-6 remained significant after further adjustment for other B vitamins. Marine-origin n-3 polyunsaturated fatty acid intake showed an inverse association, but this was not independent of intakes of B vitamins. For foods, pulses, fish and shellfish, and vegetables were independently and inversely associated with homocysteine concentration, but these associations disappeared after adjustment for intakes of other foods. Conversely, an inverse association for dairy products and a positive association for green and oolong tea remained even after adjustment for other foods. To conclude, in a group of young Japanese women, higher intake of vitamin B-6 and dairy products and lower intake of green and oolong tea were independently associated with lower serum homocysteine concentration.

Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women.

BACKGROUND: Vitamin K2 contributes to bone and cardiovascular health. Therefore, two vitamin K2 homologues, menaquinone-4 (MK-4) and menaquinone-7 (MK-7), have been used as nutrients by the food industry and as nutritional supplements to support bone and cardiovascular health. However, little is known about the bioavailability of nutritional MK-4. To investigate MK-4 and MK-7 bioavailability, nutritional doses were administered to healthy Japanese women. FINDINGS: Single dose administration of MK-4 (420 µg; 945 nmol) or MK-7 (420 µg; 647 nmol) was given in the morning together with standardized breakfast. MK-7 was well absorbed and reached maximal serum level at 6 h after intake and was detected up to 48 h after intake. MK-4 was not detectable in the serum of all subjects at any time point. Consecutive administration of MK-4 (60 µg; 135 nmol) or MK-7 (60 µg; 92 nmol) for 7 days demonstrated that MK-4 supplementation did not increase serum MK-4 levels. However, consecutive administration of MK-7 increased serum MK-7 levels significantly in all subjects. CONCLUSIONS: We conclude that MK-4 present in food does not contribute to the vitamin K status as measured by serum vitamin K levels. MK-7, however significantly increases serum MK-7 levels and therefore may be of particular importance for extrahepatic tissues.

[Dietary reference intakes of phosphorus].

Phosphorus (P) exists at the all organs and plays important physiological roles in the body. A wide range of food contains P, which is absorbed at a higher level (60-70%) and its insufficiency and deficiency are rarely found. P is used as food additives in many processed food, where risk of overconsumption could be an issue. P has less evidence in terms of nutrition. P has the adequate intake and the tolerable upper intake level, for risk reduction of health disorders associated with excess intake, at the Dietary Reference Intakes for Japanese (2010 edition).

[Is calcium supplement useful in aged persons? Calcium supplement reduce the fracture risk in aged persons].

Some reports suggest that the adequate calcium intake is effective in bone mass maintenance in elderly people. About the relation between calcium intake and fracture, there are few effects only by the calcium intake, and there are the effects by the combining with vitamin D. Also when using the medicine of osteoporosis, the adequate calcium intake is required. Especially Japanese has the low calcium intake level therefore needs the adequate calcium intake.

[Nutrition and bone health. Food for specified health use (FOSHU) and bone health].

It is known that food has biological regulation functions. The Food for Specified Health Use (FOSHU) is the food, of which a functional component was identified, of which the biological regulation function has been confirmed in clinical trials, and of which a health claim was permitted by the Ministry of Health, Labor and Welfare. Currently, three categories of Food for Specified Health Use exist concerning bone health: foods helping mineral absorption, foods helping mineral absorption and conditioning the intestines, and foods for people concerned about bone health. Incorporating Food for Specified Health Use properly into diet could help bone health.

[Phosphorus intake and bone health].

Phosphorus, which constitutes hydroxyapatite with calcium, is a important component of bone. It is considered that there is no need to worry about the lack of phosphorus in the ordinary dietary habits, because a various of foods contain phosphorus. Recently, an excess intake of phosphorus is considered a problem, because phosphorus is frequently used as a food additive. It has been reported that parathyroid hormone and bone resorption markers are increased in case of low calcium/phosphorus intake ratio. In the Dietary reference intakes for Japanese, 2010, shows 3,000 mg/day as a tolerable upper intake level of phosphorus. Some issues such as the intake ratio of calcium to phosphorus and an effect of organic phosphorus and inorganic phosphorus remain to be solved.

[Evidence of dietary therapy for osteoporosis].

A significant point of dietary therapy for osteoporosis is that calcium, vitamin D and vitamin K are recommended to be actively administered on top of sufficient intake of energy and the other nutrients including protein. In Japanese guidelines for the prevention and treatment of osteoporosis 2006 edition, daily intake of calcium and vitamin D is encouraged at least 800mg and 400 to 800IU (10 to 20microg) , respectively. Calcium and vitamin D are also important for maximizing the effect of drug for osteoporosis. Calcium and vitamin D supplementation could be a supportive measure, when their necessary requirement is difficult to be consumed.

Effect of lactulose on calcium and magnesium absorption: a study using stable isotopes in adult men.

To evaluate the effect of lactulose on calcium (Ca) and magnesium (Mg) absorption, we performed a clinical trial with a double-blind, randomized, crossover design in 24 healthy adult male volunteers. The absorptions of Ca and Mg were evaluated by a single-labeling method using stable isotopes. The test foods, containing lactulose at a dose of 0 g (placebo), 2 g (low-dose), or 4 g (high-dose) together with 300 mg of Ca containing 20 mg of 44Ca, and 150 mg of Mg containing 28 mg of 25Mg, were administered orally. Urine samples were collected for 8 h after the ingestion of the test food. The ratios of stable isotopes in urine (44Ca/40Ca and 25Mg/24Mg) were measured by ICP-MS (inductively coupled plasma-mass spectrometry). The urinary stable-isotopes ratios (44Ca/40Ca and 25Mg/24Mg) increased with lactulose dosage. Significant differences were observed in the Ca ratio between placebo and high-dose lactulose (p<0.01), and in the Mg ratio between placebo and low-dose lactulose and between placebo and high-dose lactulose (p<0.01). Lactulose ingestion did not change the levels of bone-resorption markers (type I collagen cross-linked N-telopeptide and deoxypyridinoline) in urine. The test foods did not cause any side effects. This study demonstrates that lactulose enhances the absorptions of Ca and Mg in adult men.

Vitamin K content of foods and dietary vitamin K intake in Japanese young women.

Several reports indicate an important role for vitamin K in bone health as well as blood coagulation. However, the current Adequate Intakes (AI) might not be sufficient for the maintenance of bone health. To obtain a closer estimate of dietary intake of phylloquinone (PK) and menaquinones (MKs), PK, MK-4 and MK-7 contents in food samples (58 food items) were determined by an improved high-performance liquid chromatography method. Next, we assessed dietary vitamin K intake in young women living in eastern Japan using vitamin K contents measured here and the Standard Tables of Food Composition in Japan. PK was widely distributed in green vegetables and algae, and high amounts were found in spinach and broccoli (raw, 498 and 307 microg/100 g wet weight, respectively). Although MK-4 was widely distributed in animal products, overall MK-4 content was lower than PK. MK-7 was observed characteristically in fermented soybean products such as natto (939 microg/100 g). The mean total vitamin K intake of all subjects (using data from this study and Japanese food composition tables) was about 230 microg/d and 94% of participants met the AI of vitamin K for women aged 18-29 y in Japan, 60 microg/d. The contributions of PK, MK-4 and MK-7 to total vitamin K intake were 67.7, 7.3 and 24.9%, respectively. PK from vegetables and algae and MK-7 from pulses (including fermented soybean foods) were the major contributors to the total vitamin K intake of young women living in eastern Japan.

[Prevention of osteoporosis by foods and dietary supplements. Prevention of osteoporosis by milk and dairy products].

Milk and dairy products, which are rich in calcium and high in calcium absorption, are useful foods for prevention of osteoporosis. Milk and dairy products are not only good sources for protein, lipids, sodium, potassium, phosphate, zinc, and vitamins A and B(2), and also contain functional compounds including milk basic protein (MBP), casein phosphopeptide (CPP), and lactoferrin, which are beneficial for bone health. Since some reports show that the preventive effect of dairy products consumption for bone fracture is not strong enough, but the effects may be more efficient in Japanese, whose calcium consumption is low. Consumption of milk and dairy products in Japanese is still low, and it is important to keep our mind to increase its consumption for bone health.

[Nutritional care and management for osteoporosis].

A significant point of nutritional care and management for osteoporosis is that calcium and vitamin D are recommended to be actively administered on top of sufficient intake of energy and the other nutrients including protein. Daily intake of calcium and vitamin D is encouraged at least 800 mg and 10 to 20 microg, respectively. Calcium and vitamin D are also important for maximizing the effect of osteoporosis drug therapy. Supplement of calcium or vitamin D could be a supportive measure, when their necessary amount is difficult to be consumed.