Intake of fermented soybeans, natto, is associated with reduced bone loss in postmenopausal women: Japanese Population-Based Osteoporosis (JPOS) Study

High resolution LC-ESI-TOF-mass spectrometry method for fast separation, identification, and quantification of 12 isoflavones in soybeans and soybean products

A high resolution LC-ESI-TOF-MS analytical method was established for the rapid isolation, identification, and quantification of 12 isoflavones in soybean and soybean products. Individual isoflavones were identified on the basis of the accurate mass data of their respective protonated mass ions, Na or K adduct ions, fragment ions, and isotope ion patterns. The protonated mass ions of isoflavones were extracted for their quantification in soybean products. Twelve different isoflavones in the soybean products were fully separated, identified and quantified within 12min separation time. The established LC-TOF/MS was an effective analytical method for the simultaneous characterization and quantification of isoflavones with exceptionally short analytical time, high selectivity, a high linearity (r(2)>0.992) in a wide range, low LOD and LOQ, high precision, inter-and intra-day repeatability, and no significant matrix effect. Furthermore, it requires simple sample preparation procedure (solvent extraction, dilution, and syringe filtration).

Soy isoflavone intake and bone mineral density in breast cancer survivors

PURPOSE

Low bone mineral density (BMD) is common among breast cancer survivors due to acute estrogen deprivation. Soy food is a rich source of phytoestrogens, namely isoflavones, known to have both estrogenic and anti-estrogenic effects. The objective of the study was to assess the association between soy consumption and BMD in breast cancer survivors, which has not previously been evaluated.

METHODS

Forearm BMD was evaluated using dual-energy X-ray absorptiometry at 60 months post-diagnosis for 1,587 participants of the Shanghai Breast Cancer Survival Study. Soy intakes collected at 6, 18, and 36 months post-diagnosis were averaged, and the association with BMD, osteopenia, and osteoporosis was evaluated using linear and logistic regression.

RESULTS

The mean (standard deviation) intake of isoflavones was 48.1 (28.0) mg/day. Soy intake was inversely associated with BMD and positively associated with osteoporosis. Compared with the lowest quartile, the highest quartile of soy isoflavone intake, ≥ 62.64 mg/day, was associated with a reduction of BMD by 1.95% [95% confidence interval (CI) -3.54, -0.36%] and an increased odds ratio of 1.69 for osteoporosis (95% CI 1.09, 2.61). The inverse association was predominantly seen among women who recently entered menopause (≤ 5 years).

CONCLUSION

In contrast to observations from general populations, high soy intake (≥ 62.64 mg of soy isoflavone/day) was associated with lower proximal forearm BMD among breast cancer survivors, particularly during the early years of menopause. Our finding needs to be replicated, particularly in studies with more comprehensive bone density evaluation.

Soy food consumption, cardiometabolic alterations and carotid intima-media thickness in Chinese adults

BACKGROUND AND AIM

The associations between soy food consumption, cardiometabolic disturbances and subclinical atherosclerosis remain controversial due to limited evidence. We examined the associations of habitual soy food consumption with cardiometabolic disturbances and carotid intima-media thickness (CIMT).

METHODS AND RESULTS

We included 2939 subjects (2135 women and 804 men) aged 50-75 years in this community-based cross-sectional study. Dietary data and other covariates were collected using interviewer-administered questionnaires. We determined CIMT in relation to each subject's common carotid artery, internal carotid artery, carotid bifurcation, blood lipids, glucose and urine acid, blood pressure and waist circumference. A logistic regression model was applied to estimate the odd ratios (ORs) and 95% confidence intervals (CIs), and linear regression was used to estimate the regression coefficient and 95% CIs. After adjusting for potential confounders, we found that greater consumption of soy protein (6.1 vs. 0.5 g/d) was inverse associated with the presence of elevated total cholesterol (TC), dyslipidemia, abdominal obesity and hyperuricemia in women, and with abdominal obesity in men, although no significant sex-soy interactions were observed (P: 0.145-0.985). The consumption of soy protein and isoflavones was inversely associated with the number of cardiometabolic disturbances among women, but not men. There were no significant associations of soy protein and isoflavones with CIMT thickening and other cardiometabolic disturbances.

CONCLUSION

Greater soy consumption was associated with a lower presence of elevated TC, dyslipidemia, hyperuricemia and less number of cardiometabolic disturbances components in women.

Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women

We have investigated whether low-dose vitamin K2 supplements (menaquinone-7, MK-7) could beneficially affect bone health. Next to an improved vitamin K status, MK-7 supplementation significantly decreased the age-related decline in bone mineral density and bone strength. Low-dose MK-7 supplements may therefore help postmenopausal women prevent bone loss.

INTRODUCTION

Despite contradictory data on vitamin K supplementation and bone health, the European Food Safety Authorities (EFSA) accepted the health claim on vitamin K's role in maintenance of normal bone. In line with EFSA's opinion, we showed that 3-year high-dose vitamin K1 (phylloquinone) and K2 (short-chain menaquinone-4) supplementation improved bone health after menopause. Because of the longer half-life and greater potency of the long-chain MK-7, we have extended these investigations by measuring the effect of low-dose MK-7 supplementation on bone health.

METHODS

Healthy postmenopausal women (n = 244) received for 3 years placebo or MK-7 (180 μg MK-7/day) capsules. Bone mineral density of lumbar spine, total hip, and femoral neck was measured by DXA; bone strength indices of the femoral neck were calculated. Vertebral fracture assessment was performed by DXA and used as measure for vertebral fractures. Circulating uncarboxylated osteocalcin (ucOC) and carboxylated OC (cOC) were measured; the ucOC/cOC ratio served as marker of vitamin K status. Measurements occurred at baseline and after 1, 2, and 3 years of treatment.

RESULTS

MK-7 intake significantly improved vitamin K status and decreased the age-related decline in BMC and BMD at the lumbar spine and femoral neck, but not at the total hip. Bone strength was also favorably affected by MK-7. MK-7 significantly decreased the loss in vertebral height of the lower thoracic region at the mid-site of the vertebrae.

CONCLUSIONS

MK-7 supplements may help postmenopausal women to prevent bone loss. Whether these results can be extrapolated to other populations, e.g., children and men, needs further investigation.

The role of menaquinones (vitamin K₂) in human health

Recent reports have attributed the potential health benefits of vitamin K beyond its function to activate hepatic coagulation factors. Moreover, several studies have suggested that menaquinones, also known as vitamin K2, may be more effective in activating extra-hepatic vitamin K-dependent proteins than phylloquinone, also known as vitamin K1. Nevertheless, present dietary reference values (DRV) for vitamin K are exclusively based on phylloquinone, and its function in coagulation. The present review describes the current knowledge on menaquinones based on the following criteria for setting DRV: optimal dietary intake; nutrient amount required to prevent deficiency, maintain optimal body stores and/or prevent chronic disease; factors influencing requirements such as absorption, metabolism, age and sex. Dietary intake of menaquinones accounts for up to 25% of total vitamin K intake and contributes to the biological functions of vitamin K. However, menaquinones are different from phylloquinone with respect to their chemical structure and pharmacokinetics, which affects bioavailability, metabolism and perhaps impact on health outcomes. There are significant gaps in the current knowledge on menaquinones based on the criteria for setting DRV. Therefore, we conclude that further investigations are needed to establish how differences among the vitamin K forms may influence tissue specificities and their role in human health. However, there is merit for considering both menaquinones and phylloquinone when developing future recommendations for vitamin K intake.

Hypotension associated with menaquinone

PURPOSE

A case of mild symptomatic hypotension after treatment with menaquinone (vitamin K(2)) is reported.

SUMMARY

A 62-year-old white man with a medical history of hyperlipidemia, coronary artery disease, and benign prostatic hyperplasia was started on a regimen of menaquinone 100 μg daily as a supplement to his medications for coronary artery disease. Approximately two hours after taking the first dose of menaquinone, the patient experienced sudden weakness and dizziness. At that time, his blood pressure was 110/55 mm Hg. On day 2 of treatment, his blood pressure was 105/50 mm Hg two hours after taking menaquinone; however the patient was asymptomatic. On day 3, the patient's blood pressure was 100/50 mm Hg two hours after menaquinone ingestion, with symptoms of generalized weakness and dizziness, at which point menaquinone was discontinued. All of the patient's heart rate measurements were within normal limits during this time. The day after discontinuing menaquinone, the patient's blood pressure was 115/65 mm Hg, after which his readings were within normal limits on subsequent days. After a 10-day menaquinone-free period, the patient was rechallenged. On rechallenge day 1, the patient's blood pressure was 115/60 mm Hg two hours after menaquinone ingestion; on rechallenge day 2, his blood pressure was 100/55 mm Hg. The patient was asymptomatic on both days of the rechallenge. The Naranjo et al. adverse drug reaction probability scale score was 7, indicating a probable adverse reaction to menaquinone. The drug interaction probability scale score for this case was 6, indicating that a drug interaction was probable.

CONCLUSION

A 62-year-old white man developed mild symptomatic hypotension while receiving menaquinone therapy.

Association between vitamin K intake from fermented soybeans, natto, and bone mineral density in elderly Japanese men: the Fujiwara-kyo Osteoporosis Risk in Men (FORMEN) study

SUMMARY

A cross-sectional analysis of 1,662 community dwelling elderly Japanese men suggested that habitual natto intake was significantly associated with higher bone mineral density (BMD). When adjustment was made for undercarboxylated osteocalcin levels, this association was insignificant, showing the natto-bone association to be primarily mediated by vitamin K.

INTRODUCTION

Low vitamin K intake is associated with an increased risk of hip fracture, but reports have been inconsistent on its effect on BMD. Our first aim was to examine the association between BMD and intake of fermented soybeans, natto, which contain vitamin K1 (20 μg/pack) and K2 (380 μg/pack). Our second aim was to examine the association between undercarboxylated osteocalcin (ucOC), a biomarker of vitamin K intake, and BMD to evaluate the role of vitamin K in this association.

METHODS

Of the Japanese men aged ≥65 years who participated in the baseline survey of the Fujiwara-kyo Osteoporosis Risk in Men study, 1,662 men without diseases or medications known to affect bone metabolism were examined for associations between self-reported natto intake or serum ucOC levels with lumbar spine or hip BMD.

RESULTS

The subjects with greater intake of natto showed significantly lower level of serum ucOC. Analysis after adjustment for confounding variables showed an association of greater intake of natto with both significantly higher BMD and lower risk of low BMD (T-score < -1 SD) at the total hip and femoral neck. This association became insignificant after further adjustment for ucOC level.

CONCLUSION

Habitual intake of natto was associated with a beneficial effect on bone health in elderly men, and this association is primarily due to vitamin K content of natto, although the lack of information on dietary nutrient intake, including vitamin K1 and K2, prevented us from further examining the association.

Serum undercarboxylated osteocalcin levels are inversely associated with glycemic status and insulin resistance in an elderly Japanese male population: Fujiwara-kyo Osteoporosis Risk in Men (FORMEN) Study

SUMMARY

Recent animal studies have demonstrated that undercarboxylated osteocalcin upregulates insulin secretion via osteoblast-insulin signaling. However, it remains unclear whether such a pathway exists in humans. This study showed that serum undercarboxylated osteocalcin levels were inversely associated with fasting plasma glucose, hemoglobin A(1c), and homeostasis model assessment of insulin resistance (HOMA-IR) levels in community-dwelling elderly Japanese men.

INTRODUCTION

Undercarboxylated osteocalcin (ucOC) was reported to increase insulin secretion and improve glucose tolerance via osteoblast-insulin signaling in animal-based studies. Whether this pathway also exists in humans is unknown. We aimed to clarify whether serum ucOC levels are associated with glycemic status and insulin resistance in the general Japanese population.

METHODS

We included 2,174 Japanese men (≥65 years) who were able to walk without aid from others and lived at home in four cities of Nara Prefecture. We excluded participants with a history of diseases or medications that affect bone metabolism, other than type 2 diabetes mellitus (T2DM). Fasting plasma glucose, glycated hemoglobin A(1c), and HOMA-IR levels were determined as outcome measures.

RESULTS

Of the 1,597 participants included in the analysis, both intact OC (iOC) and ucOC levels showed significant inverse correlations with all outcome measures, even after adjusting for potential confounders. Mean values of outcome measures showed a significant decreasing trend with higher quintiles of iOC or ucOC after adjusting for confounders. This trend remained significant for ucOC quintiles after further adjustment for iOC levels, but was not significant for iOC quintiles after adjusting for ucOC levels. These results were attenuated, but still apparent, after excluding participants receiving drug therapy for T2DM.

CONCLUSIONS

Levels of ucOC, but not iOC, were inversely associated with glycemic index and insulin resistance in a population of Japanese men. These findings will need to be confirmed with longitudinal studies.

Nutritional and biochemical parameters associated with 6-year change in bone mineral density in community-dwelling Japanese women aged 69 years and older: The Muramatsu Study

OBJECTIVE

Predictors of bone loss in elderly Asian women have been unclear. This cohort study aimed to assess lifestyle, nutritional, and biochemical predictors of bone loss in elderly Japanese women.

METHODS

Subjects included 389 community-dwelling women aged 69 y and older from the Muramatsu cohort initiated in 2003; follow-up ended in 2009. We obtained data on physical characteristics, osteoporosis treatment (with bisphosphonates or selective estrogen receptor modulators), physical activity, calcium intake, serum 25-hydroxyvitamin D, undercarboxylated osteocalcin, serum albumin, and bone turnover markers as predictors. The outcome was a 6-y change in forearm BMD (ΔBMD). Osteoporosis treatment was coded as 0 for none, 1 for sometimes, and 2 for always during the follow-up period. Stepwise multiple linear regression analysis was used to identify independent predictors of ΔBMD.

RESULTS

Mean age of the subjects was 73.3 y. Mean values of ΔBMD and Δweight were -0.019 g/cm(2) (-5.8%) and -2.2 kg, respectively. Stepwise multiple linear regression analysis revealed baseline BMD (β = -0.137, P < 0.0001), osteoporosis treatment (β = 0.0068, P = 0.0105), serum albumin levels (β = 0.0122, P = 0.0319), and Δweight (β = 0.0015, P = 0.0009) as significant independent predictors of ΔBMD. However, none of the other nutritional or biochemical indices were found to be significant predictors of ΔBMD.

CONCLUSIONS

Our findings indicate that adequate general nutrition and appropriate osteoporosis medication, rather than specific nutritional regimens, may be effective in preventing bone loss in elderly women.

Safety and toxicological evaluation of a synthetic vitamin K2, menaquinone-7

Menaquinone-7 (MK-7) is part of a family of vitamin K that are essential co-factors for the enzyme γ-glutamyl carboxylase, which is involved in the activation of γ-carboxy glutamate (Gla) proteins in the body. Gla proteins are important for normal blood coagulation and normality of bones and arteries. The objective of this study was to examine the potential toxicity of synthetic MK-7 in BomTac:NMRI mice and in Sprague-Dawley rats. In an acute oral toxicity test, mice were administered a single oral dose of 2000 mg/kg body weight (limit dose) and no toxicity was observed during the 14-day observation period. In the subchronic oral toxicity test in rats, animals were administered MK-7 for 90 days by gavage at the following doses: 0 (vehicle control, corn oil), 2.5, 5, and 10 mg/kg body weight/day. All generated data, including clinical observations, ophthalmology, clinical pathology, gross necropsy, and histopathology, revealed no compound-related toxicity in rats. Any statistically significant findings in clinical pathology parameters and/or organ weights noted were considered to be within normal biological variability. Therefore, under the conditions of this experiment, the median lethal dose (LD₅₀) of MK-7 after a single oral administration in mice was determined to be greater than the limit dose level of 2000 mg/kg body weight. The no observed adverse effect level (NOAEL) of MK-7, when administered orally to rats for 90 days, was considered to be equal to 10 mg/kg body weight/day, the highest dose tested, based on lack of toxicity during the 90-day study period.

Characterization of Bacillus phage-K2 isolated from chungkookjang, a fermented soybean foodstuff

An investigation of a virulent Bacillus phage-K2 (named Bp-K2) isolated from chungkookjang (a fermented soybean foodstuff) was made. Bp-K2 differed in infectivity against a number of Bacillus subtilis strains including starter strains of chungkookjang and natto, being more infectious to Bacillus strains isolated from the chungkookjang, but much less active against a natto strain. Bp-K2 is a small DNA phage whose genome size is about 21 kb. Bp-K2 is a tailed bacteriophage with an isometric icosahedral head (50 nm long on the lateral side, 80 nm wide), a long contractile sheath (85-90 nm × 28 nm), a thin tail fiber (80-85 nm long, 10 nm wide), and a basal plate (29 nm long, 47 nm wide) with a number of spikes, but no collar. The details of the structures of Bp-K2 differ from natto phage ϕBN100 as well as other known Bacillus phages such as SPO1-like or ϕ 29-like viruses. These data suggest that Bp-K2 would be a new member of the Myoviridae family of Bacillus bacteriophages.

Soy components vs. whole soy: are we betting our bones on a long shot?

Soybeans are a good source of bone-healthy nutrients. Epidemiological studies in Asia evaluating diets containing traditional whole soy foods show a positive association with bone mineral density and fracture protection. Smaller scale intervention studies in Western nations mainly feature isolated soy protein (SP) and purified or concentrated soy isoflavones (SI) rather than whole soy foods and they have produced inconsistent results. Consumption of SP does not alter calcium (Ca) retention even though urinary Ca excretion is less in diets with SP compared with proteins higher in sulfur-containing amino acids. SI, often consumed at higher concentrations than would be available in traditional Asian diets, are not yielding the type of incontrovertible evidence that might be expected in support of their benefit to bone health. This forces one to ask whether whole soy might provide a superior effect on bone.

Phytoestrogens and bone health

PURPOSE OF REVIEW

The present review summarizes the results of epidemiological studies and clinical trials assessing the skeletal effects of soy foods and soy dietary supplements.

RECENT FINDINGS

Results from epidemiological studies suggest a beneficial skeletal effect in Asian women consuming typical Asian diets, but clinical trials are conflictive regarding the effects of phytoestrogens on bone mineral density and bone turnover markers in premenopausal and postmenopausal women. Much of the controversy lies in differences in study design, reporting of results, participants' age and menopausal status, and type and dose of phytoestrogen used.

SUMMARY

Although western women will likely continue to incorporate soy foods and soy supplements into their diets with the increased availability of these products, published data are inconsistent and do not support soy's protective effect against bone loss. This conflicting evidence should be taken into account when considering using isoflavones in the prevention of bone loss and consequently fractures.

Dietary patterns associated with fall-related fracture in elderly Japanese: a population based prospective study

BACKGROUND

Diet is considered an important factor for bone health, but is composed of a wide variety of foods containing complex combinations of nutrients. Therefore we investigated the relationship between dietary patterns and fall-related fractures in the elderly.

METHODS

We designed a population-based prospective survey of 1178 elderly people in Japan in 2002. Dietary intake was assessed with a 75-item food frequency questionnaire (FFQ), from which dietary patterns were created by factor analysis from 27 food groups. The frequency of fall-related fracture was investigated based on insurance claim records from 2002 until 2006. The relationship between the incidence of fall-related fracture and modifiable factors, including dietary patterns, were examined. The Cox proportional hazards regression model was used to examine the relationships between dietary patterns and incidence of fall-related fracture with adjustment for age, gender, Body Mass Index (BMI) and energy intake.

RESULTS

Among 877 participants who agreed to a 4 year follow-up, 28 suffered from a fall-related fracture. Three dietary patterns were identified: mainly vegetable, mainly meat and mainly traditional Japanese. The moderately confirmed (see statistical methods) groups with a Meat pattern showed a reduced risk of fall-related fracture (Hazard ratio = 0.36, 95% CI = 0.13 - 0.94) after adjustment for age, gender, BMI and energy intake. The Vegetable pattern showed a significant risk increase (Hazard ratio = 2.67, 95% CI = 1.03 - 6.90) after adjustment for age, gender and BMI. The Traditional Japanese pattern had no relationship to the risk of fall-related fracture.

CONCLUSIONS

The results of this study have the potential to reduce fall-related fracture risk in elderly Japanese. The results should be interpreted in light of the overall low meat intake of the Japanese population.

Association between lifestyle habits and bone mineral density in Japanese juveniles

OBJECTIVES

We explored the relationship between bone mineral density (BMD) and lifestyle in juveniles to identify factors leading to higher peak bone mass and prevention of osteoporosis in later life.

METHODS

Juveniles (1,364 students: 770 boys and 594 girls, aged 6-18 years) attending school in Hokkaido prefecture, Japan, were asked to complete a brief self-administered diet history questionnaire for 10-year-olds (BDHQ10y) providing information about personal history, lifestyle, and intake of nutritional elements. In addition, BMD and grip strength were measured. We analyzed the relationship between BMD and lifestyle factors.

RESULTS

The difference in BMD for boys was larger among the junior and senior high school groups. The difference in BMD for girls was larger among older elementary and later school children. Anthropometric variables and grip strength were strongly correlated with BMD. Having a nap-time routine was significantly correlated with BMD, but sleep time and sports club activities were not. BMD among juveniles who attained secondary sexual characteristics was significantly higher than that of juveniles of the same age who had not attained these characteristics. Calcium intake was significantly lower in senior high school students compared with other grades. Consumption of milk by senior high school boys and junior high school girls was weakly correlated with BMD.

CONCLUSIONS

Our findings encourage educational interventions to counsel students to avoid weight loss and calcium deficiency. This effective intervention should begin before the higher elementary school, when juveniles have the greatest likelihood for preventing lower peak bone mass and osteoporosis.

The soy isoflavones for reducing bone loss (SIRBL) study: a 3-y randomized controlled trial in postmenopausal women

BACKGROUND

Our previous study indicated that soy protein with isoflavones lessened lumbar spine bone loss in midlife women.

OBJECTIVE

We examined the efficacy of isoflavones (extracted from soy protein) on bone mineral density (BMD) in nonosteoporotic postmenopausal women. We hypothesized that isoflavone tablets would spare BMD, with biological (age, body weight, serum 25-hydroxyvitamin D) and lifestyle (physical activity, dietary intake) factors modulating BMD loss.

DESIGN

Our double-blind, randomized controlled trial (36 mo) included healthy postmenopausal women (aged 45.8-65.0 y) with intent-to-treat (n = 224) and compliant (n = 208) analyses. Treatment groups consisted of a placebo control group and 2 soy isoflavone groups (80 compared with 120 mg/d); women received 500 mg calcium and 600 IU vitamin D(3). Outcomes included lumbar spine, total proximal femur, femoral neck, and whole-body BMD.

RESULTS

Analysis of variance for intent-to-treat and compliant (> or =80%) models, respectively, showed no treatment effect for spine (P = 0.46, P = 0.21), femur (P = 0.86, P = 0.46), neck (P = 0.17, P = 0.14), or whole-body (P = 0.86, P = 0.78) BMD. From baseline to 36 mo, BMD declined regardless of treatment. In intent-to-treat and compliant models, respectively, BMD decreases were as follows: spine (-2.08%, -1.99%), femur (-1.43%, -1.38%), neck (-2.56%, -2.51%), and whole body (-1.66%, -1.62%). Regression analysis (compliant model) indicated that age, whole-body fat mass, and bone resorption were common predictors of BMD change. After adjustment for these factors, 120 mg (compared with placebo) was protective (P = 0.024) for neck BMD. We observed no treatment effect on adverse events, endometrial thickness, or bone markers.

CONCLUSION

Our results do not show a bone-sparing effect of extracted soy isoflavones, except for a modest effect at the femoral neck. This trial was registered at clinicaltrials.gov as NCT00043745.

Gender-specific associations between soy and risk of hip fracture in the Singapore Chinese Health Study

Although there is some epidemiologic evidence that soy may reduce risk of osteoporotic fracture in women, it is not known whether this risk reduction also occurs for men. The authors examined gender-specific associations between soy intake and hip fracture risk in the Singapore Chinese Health Study, a prospective cohort of 63,257 Chinese living in Singapore. At recruitment between 1993 and 1998, each subject was administered a food frequency questionnaire and questions on medical history and lifestyle factors. As of December 31, 2006, 276 incident cases of hip fracture in men and 692 cases in women were identified via linkage with hospital discharge databases. For both genders, hip fracture risk was positively associated with cigarette smoking and was inversely associated with body mass index. There was a statistically significant association of tofu equivalents, soy protein, and isoflavones with hip fracture risk among women but not among men. Compared with women in the lowest quartile of intakes for tofu equivalents (<49.4 g/day), soy protein (<2.7 g/day), and isoflavones (<5.8 mg/1,000 kcal/day), those in the second-fourth quartiles exhibited 21%-36% reductions in risk (all P < 0.036). Risk levels were comparable across the second, third, and fourth quartiles of soy intake categories.

Vitamin K, an example of triage theory: is micronutrient inadequacy linked to diseases of aging?

The triage theory posits that some functions of micronutrients (the approximately 40 essential vitamins, minerals, fatty acids, and amino acids) are restricted during shortage and that functions required for short-term survival take precedence over those that are less essential. Insidious changes accumulate as a consequence of restriction, which increases the risk of diseases of aging. For 16 known vitamin K-dependent (VKD) proteins, we evaluated the relative lethality of 11 known mouse knockout mutants to categorize essentiality. Results indicate that 5 VKD proteins that are required for coagulation had critical functions (knockouts were embryonic lethal), whereas the knockouts of 5 less critical VKD proteins [osteocalcin, matrix Gla protein (Mgp), growth arrest specific protein 6, transforming growth factor beta-inducible protein (Tgfbi or betaig-h3), and periostin] survived at least through weaning. The VKD gamma-carboxylation of the 5 essential VKD proteins in the liver and the 5 nonessential proteins in nonhepatic tissues sets up a dichotomy that takes advantage of the preferential distribution of dietary vitamin K1 to the liver to preserve coagulation function when vitamin K1 is limiting. Genetic loss of less critical VKD proteins, dietary vitamin K inadequacy, human polymorphisms or mutations, and vitamin K deficiency induced by chronic anticoagulant (warfarin/coumadin) therapy are all linked to age-associated conditions: bone fragility after estrogen loss (osteocalcin) and arterial calcification linked to cardiovascular disease (Mgp). There is increased spontaneous cancer in Tgfbi mouse knockouts, and knockdown of Tgfbi causes mitotic spindle abnormalities. A triage perspective reinforces recommendations of some experts that much of the population and warfarin/coumadin patients may not receive sufficient vitamin K for optimal function of VKD proteins that are important to maintain long-term health.

Roles for vitamin K beyond coagulation

Recent interest in vitamin K has been motivated by evidence of physiological roles beyond that of coagulation. Vitamin K and vitamin K-dependent (VKD) proteins may be involved in regulation of calcification, energy metabolism, and inflammation. However, the evidence for many of these proposed roles in the maintenance of health is equivocal. There is also an emerging viewpoint that the biochemical function of vitamin K may extend beyond that of a cofactor for the VKD carboxylation of glutamyl residues (Glus) to carboxylated Glus in VKD proteins.

Soy proteins and isoflavones affect bone mineral density in older women: a randomized controlled trial

BACKGROUND

Soy foods contain several components (isoflavones and amino acids) that potentially affect bone. Few long-term, large clinical trials of soy as a means of improving bone mineral density (BMD) in late postmenopausal women have been conducted.

OBJECTIVE

Our goal was to evaluate the long-term effect of dietary soy protein and/or soy isoflavone consumption on skeletal health in late postmenopausal women.

DESIGN

We conducted a randomized, double-blind, placebo-controlled clinical trial in 131 healthy ambulatory women aged >60 y. Ninety-seven women completed the trial. After a 1-mo baseline period, subjects were randomly assigned into 1 of 4 intervention groups: soy protein (18 g) + isoflavone tablets (105 mg isoflavone aglycone equivalents), soy protein + placebo tablets, control protein + isoflavone tablets, and control protein + placebo tablets.

RESULTS

Consumption of protein powder and isoflavone pills did not differ between groups, and compliance with the study powder and pills was 80-90%. No significant differences in BMD were observed between groups from baseline to 1 y after the intervention or in BMD change between equol and non-equol producers. However, there were significant negative correlations between total dietary protein (per kg) and markers of bone turnover (P < 0.05).

CONCLUSIONS

Because soy protein and isoflavones (either alone or together) did not affect BMD, they should not be considered as effective interventions for preserving skeletal health in older women. The negative correlation between dietary protein and bone turnover suggests that increasing protein intakes may suppress skeletal turnover. This trial was registered at ClinicalTrials.gov as NCT00668447.

Sample preparation for the analysis of isoflavones from soybeans and soy foods

This manuscript provides a review of the actual state and the most recent advances as well as current trends and future prospects in sample preparation and analysis for the quantification of isoflavones from soybeans and soy foods. Individual steps of the procedures used in sample preparation, including sample conservation, extraction techniques and methods, and post-extraction treatment procedures are discussed. The most commonly used methods for extraction of isoflavones with both conventional and "modern" techniques are examined in detail. These modern techniques include ultrasound-assisted extraction, pressurized liquid extraction, supercritical fluid extraction and microwave-assisted extraction. Other aspects such as stability during extraction and analysis by high performance liquid chromatography are also covered.

Inhibition of P-glycoprotein in Caco-2 cells: effects of herbal remedies frequently used by cancer patients

1. The herbal products Natto K2, Agaricus, mistletoe, noni juice, green tea and garlic were investigated for in vitro inhibitory potential on P-glycoprotein (P-gp)-mediated transport of digoxin (30 nM) in differentiated and polarized Caco-2 cells. 2. Satisfactory cell functionality was demonstrated through measurements of assay linearity, transepithelial electric resistance (TEER), cytotoxicity, mannitol permeability, and inclusion of the positive inhibition control verapamil. 3. The most potent inhibitors of the net digoxin flux (IC(50)) were mistletoe > Natto K2 > Agaricus > green tea (0.022, 0.62, 3.81, >4.5 mg ml(-1), respectively). Mistletoe also showed the lowest IC(25) value, close to that obtained by verapamil (1.0 and 0.5 microg ml(-1), respectively). The IC(50)/IC(25) ratio was found to be a good parameter for the determination of inhibition profiles. Garlic and noni juice were classified as non-inhibitors. 4. This study shows that mistletoe, Natto K2, Agaricus and green tea inhibit P-gp in vitro. Special attention should be paid to mistletoe due to very low IC(50) and IC(25) values and to Natto K2 due to a low IC(50) value and a low IC(50)/IC(25) ratio.

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.

The potential role of soyfoods in weight and adiposity reduction: an evidence-based review

Evidence concerning the relationship between soyfoods and weight loss was reviewed. Detailed searches of PubMed and Web of Science were performed to identify and evaluate evidence for or against four propositions related to soyfoods and weight loss (Data from in vitro, animal, epidemiologic, and clinical studies were evaluated and summarized). (1) Certain soyfoods will improve weight and/or fat loss when fed at isolcaloric levels (similar calories given across experimental conditions, but not necessarily at a level to maintain current body weight); generally supportive evidence in animal studies, but there is no compelling support in human studies. (2) Certain soyfoods will improve weight and fat loss when included as part of a diet by affecting caloric intake; limited supportive evidence in animal and human studies. (3) Certain soyfoods will prevent/improve risk factors related to glucoregulatory function and cardiovascular health during weight loss; some evidence supporting this proposition, but additional evidence is needed before conclusions can be made. (4) Certain soyfoods will minimize the loss of bone mass during weight loss; no data available pertinent to this proposition. Limitations in existing data make it difficult to reach conclusions regarding these four propositions. Overall, the current data suggest that soyfoods are as good as other protein sources for promoting weight loss and there is a suggestive body of evidence that soyfoods may confer additional benefits, but results must be carefully interpreted and additional evidence is needed before making firm conclusions concerning soyfoods and weight loss.

Phyto-oestrogens and bone health

As oestrogen deficiency is the main cause in the pathogenesis of osteoporosis hormone-replacement therapy remains the mainstay for prevention. However, prophylaxis by hormone-replacement therapy is limited. Phyto-oestrogens, which are weakly-oestrogenic compounds present in plants, deserve particular mention because emerging data support the suggestion that they may prevent bone loss associated with the menopause. In the past few years extensive research using animal models has provided convincing data to indicate a significant improvement in bone mass or other end points following feeding with soyabean. Moreover, observational studies relate the lower incidence of osteoporosis among women in the Eastern world to a diet rich in phyto-oestrogens. However, it is not valid to extrapolate to the Western situation. The varied clinical trials that have been published suggest that isoflavones reduce bone loss in women in the early period post menopause, but a definitive result requires more investigations of the effect of phyto-oestrogens on bone health that have substantial sample size and are of long duration. In addition, the clinical efficacy of soya foods in preventing osteopenia depends on their intestinal metabolism. Thus, phyto-oestrogens are a source for putative innovative dietary health intervention for post-menopausal women. However, more data are necessary, particularly in relation to their effect on the risk of fracture.

Soybean and soy isoflavone intake indicate a positive change in bone mineral density for 2 years in young Korean women

Many studies have shown that soybean and isoflavones have a favorable effect on bone mass for postmenopausal women, but few data are available on young Asian women. To investigate the effect of soybean and isoflavone intake on bone mineral density (BMD) and its change among young Korean women over 2 years, we conducted a longitudinal study for 34 women. The BMD was measured 3 times with 1-year intervals by dual x-ray absorptiometry at the lumbar spine and femur (neck, Ward's triangle [WT], and trochanter). Dietary intake was assessed up to 8 times by 24-hour recall with average 4-month interval. During the study period, BMD increased significantly for lumber spine and WT (2.5% and 5.2%). The average daily intake of soybeans and isoflavones was 39 g and 8 mg, respectively. Soybean intake and total isoflavone intake had positive correlation on femoral neck (FN) and WT. By longitudinal mixed-model regression analysis, BMD increased 0.26% per 1 mg of isoflavone intake per year in the FN and 0.31% for WT (P = .05 and .008). In conclusion, soybean and isoflavone intake have a positive effect on the change of BMD on the FN and WT among young Korean women. Because soybean and isoflavone intakes could be confounded by other nutrients, the positive effects of isoflavones on bone should be further investigated.

An improved method for basic hydrolysis of isoflavone malonylglucosides and quality evaluation of Chinese soy materials

Basic hydrolysis procedure is often included in the sample preparation in order to quantify malonylglucosides or acetylglucosides of soy materials. However, it is preferable not to use NaOH as a hydrolytic reagent considering the effect of its alkalinity on the successive injection to HPLC and low acidity of soy isoflavones. This paper presents an improved method for basic hydrolysis using ammonia as a hydrolytic reagent without the additional neutralization step. Moreover, by means of HPLC and LC-MS methods, a systematic quality evaluation of natural soy materials from Chinese markets were established and discussed, inclusive of soybeans, black soybeans, defatted soy flours, as well as the distribution of isoflavones in the seed coat, hypocotyl and cotyledon. The results indicate that HPLC profiling patterns of originating various isoflavone constituents of Chinese soybeans was similar to those of Japanese ones, and those of Chinese black soybeans was similar to those of American ones. The average content level of total soy isoflavones of Chinese soybeans and black soybeans were a little lower than that of American and Japanese ones. Additionally, the thorough analysis for Semen Sojae Praeparatum, a Chinese herbal medicine made from fermented black soybeans or soybeans was done for the first time and the characteristic of its HPLC profiling patterns shows the higher content of isoflavone glucosides and aglycones than those of natural soy materials.