Vitamin D supplementation is an important strategy for preventing low levels of serum 25OHD and improving bone health and consequent associated health risks, especially in children at risk of deficiency. Although vitamin D supplements are recommended, there is limited research on the factors that influence adherence to taking them. In a cross-sectional sample of 256 child (aged 9–15) and parent pairs in the Boston area during January-March 2012, ANCOVA was used to determine associations between health beliefs about vitamin D, parental vitamin D-containing supplement use, and the individual responsible for pill administration with supplement adherence measured by pill counts. Mean and median supplement pill count adherence over 3-months were 84% and 89%, respectively. Adherence was positively associated with parents’ use of vitamin D-containing supplements (7% higher, P=0.008) and with combined child and parent responsibility for administration of the supplement compared to child only (9% higher, P=0.03). Parents’ beliefs about vitamin D neither predictedtheir children’s beliefs nor positively influenced children’s adherence. Adherence was higher when parents took vitamin D-containing supplements and when parents and children shared responsibility for administering the supplement. Promoting child supplement use through parent involvement and role modeling may be a practical solution for dietitians who are aiming to improve vitamin D adherence in at-risk youth.
Vitamin D; adherence; supplementation; children; parents
Although an estimated 50% of adults in the United States consume dietary supplements, analytically substantiated data on their bioactive constituents are sparse. Several programs funded by the Office of Dietary Supplements (ODS) at the National Institutes of Health enhance dietary supplement database development and help to better describe the quantitative and qualitative contributions of dietary supplements to total dietary intakes. ODS, in collaboration with the United States Department of Agriculture, is developing a Dietary Supplement Ingredient Database (DSID) verified by chemical analysis. The products chosen initially for analytical verification are adult multivitamin-mineral supplements (MVMs). These products are widely used, analytical methods are available for determining key constituents, and a certified reference material is in development. Also MVMs have no standard scientific, regulatory, or marketplace definitions and have widely varying compositions, characteristics, and bioavailability. Furthermore, the extent to which actual amounts of vitamins and minerals in a product deviate from label values is not known. Ultimately, DSID will prove useful to professionals in permitting more accurate estimation of the contribution of dietary supplements to total dietary intakes of nutrients and better evaluation of the role of dietary supplements in promoting health and well-being. ODS is also collaborating with the National Center for Health Statistics to enhance the National Health and Nutrition Examination Survey dietary supplement label database. The newest ODS effort explores the feasibility and practicality of developing a database of all dietary supplement labels marketed in the US. This article describes these and supporting projects.
Dietary supplements; Analytical substantiation; Dietary supplement composition; Dietary supplement ingredient database; NHANES; DSID; NHANES-DSLD; DSLD-USA; Dietary supplement labels; Standard reference materials®; Certified reference materials
Several activities of the Office of Dietary Supplements (ODS) at the National Institutes of Health involve enhancement of dietary supplement databases. These include an initiative with US Department of Agriculture to develop an analytically substantiated dietary supplement ingredient database (DSID) and collaboration with the National Center for Health Statistics to enhance the dietary supplement label database in the National Health and Nutrition Examination Survey (NHANES). The many challenges that must be dealt with in developing an analytically supported DSID include categorizing product types in the database, identifying nutrients, and other components of public health interest in these products and prioritizing which will be entered in the database first. Additional tasks include developing methods and reference materials for quantifying the constituents, finding qualified laboratories to measure the constituents, developing appropriate sample handling procedures, and finally developing representative sampling plans. Developing the NHANES dietary supplement label database has other challenges such as collecting information on dietary supplement use from NHANES respondents, constant updating and refining of information obtained, developing default values that can be used if the respondent cannot supply the exact supplement or strength that was consumed, and developing a publicly available label database. Federal partners and the research community are assisting in making an analytically supported dietary supplement database a reality.
Dietary supplements; Analytical substantiation; Dietary supplement composition; Dietary supplement ingredient database; NHANES; DSID; Dietary supplement labels; Certified reference materials; Standard reference materials
Research has shown that numerous dietary bioactive components that are not considered essential may still be beneficial to health. The dietary reference intake (DRI) process has been applied to nonessential nutrients, such as fiber, yet the majority of bioactive components await a recommended intake. Despite a plethora of new research over the past several years on the health effects of bioactives, it is possible that the field may never reach a point where the current DRI framework is suitable for these food components. If bioactives are to move toward dietary guidance, they will likely require an alternative path to get there.
Twenty publications from twelve prospective cohorts evaluated associations between flavonoid intakes and incidence or mortality from cardiovascular disease among adults in Europe and the United States (US). The most common outcome was coronary heart disease mortality, and four of eight cohort studies reported significant inverse associations for at least one flavonoid class (multivariate adjusted ptrend <.05). Three of seven cohorts reported that greater flavonoid intake was associated with lower risk of incident stroke. Comparisons were difficult because of variability in the flavonoid classes included, demographic characteristics of the populations, outcomes assessed, and length of follow up. The most common flavonoid classes examined were flavones and flavonols combined (11 studies). Only one study examined all seven flavonoid classes. The flavonol and flavone classes were most strongly associated with lower CHD mortality. Evidence for protection from other flavonoid classes and CVD outcomes was more limited. The hypothesis that flavonoid intakes are associated with lower CVD incidence and mortality requires further study.
flavonoids; cardiovascular disease; coronary heart disease; stroke; prospective cohort studies; United States; Europe
Protein is a macronutrient essential for growth, muscle function, immunity and overall tissue homeostasis. Suboptimal protein intake can significantly impact physical function and overall health in older adults.
This article reviews the literature on the recommendations for protein intake in older adults in light of the new evidence linking protein intake with sarcopenia and physical function. Challenges and opportunities for optimal protein nutrition in older persons are discussed.
Recent metabolic and epidemiological studies suggest that the current recommendations of protein intake may not be adequate for maintenance of physical function and optimal health in older adults. Methodological limitations and novel concepts in protein nutrition are also discussed.
We conclude that new research and novel research methodologies are necessary to establish the protein needs and optimal patterns of protein intake for older persons.
The Nutrient Data Laboratory of the United States Department of Agriculture (USDA) is collaborating with the Office of Dietary Supplements (ODS), the National Center for Health Statistics (NCHS), and other government agencies to design and populate a dietary supplement ingredient database (DSID). This analytically based, publicly available database will provide reliable estimates of vitamin and mineral content of dietary supplement (DS) products. The DSID will initially be populated with multivitamin/mineral (MVM) products because they are the most commonly consumed supplements. Challenges associated with the analysis of MVMs were identified and investigated. A pilot study addressing the identification of appropriate analytical methods, sample preparation protocols, and experienced laboratories for the analysis of 12 vitamins and 11 minerals in adult MVM supplement products was completed. Preliminary studies support the development of additional analytical studies with results that can be applied to the DSID. Total intakes from foods and supplements are needed to evaluate the associations between dietary components and health. The DSID will provide better estimates of actual nutrient intake from supplements than databases that rely on label values alone.
Dietary supplements; Analytical database; DSID; Multivitamin; Pilot study; Nutrients
To examine if children use supplements to fill gaps in nutritionally inadequate diets or whether supplements contribute to already adequate or excessive micronutrient intakes from foods.
Data were analyzed for children (2–18 y) from the NHANES 2003–2006, a nationally representative, cross-sectional survey (n=7,250). Diet was assessed using two 24-hour recalls, and dietary supplement use was assessed with a 30-day questionnaire.
Prevalence of supplements use was 21% (< 2 y) and 42% (2–8 y). Supplement users had higher micronutrient intakes than nonusers. Calcium and vitamin D intakes were low for all children. Inadequate intakes of phosphorus, copper, selenium, folate, and vitamins B-6 and B-12 were minimal from foods alone among 2–8 y olds. However, among 9–18 y olds, a higher prevalence of inadequate intakes of magnesium, phosphorus, and vitamins A, C, and E were observed. Supplement use increased the likelihood of intakes above the Upper Tolerable Intake Level for iron, zinc, copper, selenium, folic acid, and vitamins A and C.
Even with the use of supplements, more than a one-third of children failed to meet calcium and vitamin D recommendations. Children 2–8 y had nutritionally adequate diets regardless of supplement use. However, in children older than 8 y dietary supplements added micronutrients to diets that would have otherwise been inadequate for magnesium, phosphorus, vitamins A,C, and E. Supplement use contributed to the potential for excess intakes of some nutrients. These findings may have implications for reformulating dietary supplements for children.
children; NHANES; dietary supplement; users and non-users of supplements
The Nutrition Facts panel on food labels in the United States currently displays Daily Values (DVs) that are based on outdated RDAs. The FDA has indicated that it plans to update the DVs based on the newer Dietary Reference Intakes (DRIs), but there is controversy regarding the best method for calculating new DVs from the DRIs. To better understand the implications of DV revisions, assuming that manufacturers choose to maintain current label claims for micronutrients from voluntarily fortified foods, we modeled intake of 8 micronutrients using NHANES 2007–2008 data and 2 potential methods for calculating DVs: the population-weighted Estimated Average Requirement (EAR) and the population-coverage RDA. In each scenario, levels of fortified nutrients were adjusted to maintain the current %DV. Usual nutrient intakes and percentages with usual intakes less than the EAR were estimated for the U.S. population and subpopulations aged ≥4 y (n = 7976). For most nutrients, estimates of the percentage of the U.S. population with intakes below the EAR were similar regardless of whether the DV corresponded to the population-weighted EAR or the population-coverage RDA. Potential decreases were observed in adequacy of nutrients of concern for women of childbearing age, namely iron and folate (up to 9% and 3%, respectively), adequacy of calcium among children (up to 6%), and adequacy of vitamin A intakes in the total population (5%) assuming use of the population-weighted EAR compared with the population-coverage RDA for setting the DV. Results of this modeling exercise will help to inform decisions in revising the DVs.
Substantial experimental evidence suggests that several flavonoid classes are involved in glucose metabolism, but few clinical or epidemiologic studies exist that provide supporting human evidence for this relationship. The objective of this study was to determine if habitual intakes of specific flavonoid classes are related to incidence of type 2 diabetes (T2D). We followed 2915 members of the Framingham Offspring cohort who were free of T2D at baseline from 1991 to 2008. Diabetes was defined by either elevated fasting glucose (≥7.0 mmol/L) or initiation of hypoglycemic medication during follow-up. Dietary intakes of 6 flavonoid classes and total flavonoids were assessed using a validated, semiquantitative food frequency questionnaire. We observed 308 incident cases of T2D during a mean follow-up period of 11.9 y (range 2.5–16.8 y). After multivariable adjusted, time-dependent analyses, which accounted for long-term flavonoid intake during follow-up, each 2.5-fold increase in flavonol intake was associated with a 26% lower incidence of T2D [HR = 0.74 (95% CI: 0.61, 0.90); P-trend = 0.003] and each 2.5-fold increase in flavan-3-ol intake was marginally associated with an 11% lower incidence of T2D [HR = 0.89 (95% CI: 0.80, 1.00); P-trend = 0.06]. No other associations between flavonoid classes and risk of T2D were observed. Our observations support previous experimental evidence of a possible beneficial relationship between increased flavonol intake and risk of T2D.
This paper, based on the symposium “Is ‘Processed’ a Four-Letter Word? The Role of Processed Foods in Achieving Dietary Guidelines and Nutrient Recommendations in the U.S.” describes ongoing efforts and challenges at the nutrition–food science interface and public health; addresses misinformation about processed foods by showing that processed fruits and vegetables made important dietary contributions (e.g., fiber, folate, potassium, vitamins A and C) to nutrient intake among NHANES 2003–2006 participants, that major sources of vitamins (except vitamin K) were provided by enrichment and fortification and that enrichment and fortification helped decrease the percentage of the population below the Estimated Average Requirement for vitamin A, thiamin, folate, and iron; describes how negative consumer perceptions and consumer confusion about processed foods led to the development of science-based information on food processing and technology that aligns with health objectives; and examines challenges and opportunities faced by food scientists who must balance consumer preferences, federal regulations, and issues surrounding food safety, cost, unintended consequences, and sustainability when developing healthful foods that align with dietary guidelines.
More than half of US adults use dietary supplements. Some reports suggest that supplement users have higher vitamin intakes from foods than nonusers, but this observation has not been examined using nationally representative survey data.
The purpose of this analysis was to examine vitamin intakes from foods by supplement use and how dietary supplements contribute to meeting or exceeding the Dietary Reference Intakes for selected vitamins using data from the National Health and Nutrition Examination Survey among adults (aged ≥19 years) in 2003–2006 (n=8,860).
Among male users, mean intakes of folate and vitamins A, E, and K from food sources were significantly higher than among nonusers. Among women, mean intakes of folate and vitamins A, C, D, and E from foods were higher among users than nonusers. Total intakes (food and supplements) were higher for every vitamin we examined among users than the dietary vitamin intakes of nonusers. Supplement use helped lower the prevalence of intakes below the Estimated Average Requirement for every vitamin we examined, but for folic acid and vitamins A, B-6, and C, supplement use increased the likelihood of intakes above the Tolerable Upper Intake Level.
Supplement use was associated with higher mean intakes of some vitamins from foods among users than nonusers, but it was not associated with the prevalence of intakes less than the Estimated Average Requirement from foods. Those who do not use vitamin supplements had significantly higher prevalence of inadequate vitamin intakes; however, the use of supplements can contribute to excess intake for some vitamins.
Dietary supplements; NHANES; Vitamins; Users and non-users of supplements
Food composition databases are critical to assess and plan dietary intakes. Dietary supplement databases are also needed because dietary supplements make significant contributions to total nutrient intakes. However, no uniform system exists for classifying dietary supplement products and indexing their ingredients in such databases. Differing approaches to classifying these products make it difficult to retrieve or link information effectively. A consistent approach to classifying information within food composition databases led to the development of LanguaL™, a structured vocabulary. LanguaL™ is being adapted as an interface tool for classifying and retrieving product information in dietary supplement databases. This paper outlines proposed changes to the LanguaL™ thesaurus for indexing dietary supplement products and ingredients in databases. The choice of 12 of the original 14 LanguaL™ facets pertinent to dietary supplements, modifications to their scopes, and applications are described. The 12 chosen facets are: Product Type; Source; Part of Source; Physical State, Shape or Form; Ingredients; Preservation Method, Packing Medium, Container or Wrapping; Contact Surface; Consumer Group/Dietary Use/Label Claim; Geographic Places and Regions; and Adjunct Characteristics of food.
LanguaL; Government; Dietary supplements; Databases; Indexing; Structured vocabulary; Thesaurus; Food analysis; Food composition
Elite adolescent figure skaters must accommodate both the physical demands of competitive training and the accelerated rate of bone growth that is associated with adolescence, in this sport that emphasizes leanness. Although, these athletes apparently have sufficient osteogenic stimuli to mitigate the effects of possible low energy availability on bone health, the extent or magnitude of bone accrual also varies with training effects, which differ among skater disciplines.
We studied differences in total and regional bone mineral density in 36 nationally ranked skaters among 3 skater disciplines: single, pairs, and dancers.
Bone mineral density (BMD) of the total body and its regions was measured by dual energy x-ray absorptiometry (DXA). Values for total body, spine, pelvis and leg were entered into a statistical mixed regression model to identify the effect of skater discipline on bone mineralization while controlling for energy, vitamin D, and calcium intake.
The skaters had a mean body mass index of 19.8 ± 2.1 and % fat mass of 19.2 ± 5.8. After controlling for dietary intakes of energy, calcium, and vitamin D, there was a significant relationship between skater discipline and BMD (p = 0.002), with single skaters having greater BMD in the total body, legs, and pelvis than ice dancers (p < 0.001). Pair skaters had greater pelvic BMD than ice dancers (p = 0.001).
Single and pair skaters have greater BMD than ice dancers. The osteogenic effect of physical training is most apparent in single skaters, particularly in the bone loading sites of the leg and pelvis.
Elite adolescent female figure skaters compete in an aesthetic-based sport that values thin builds and lithe figures. To conform to the sport’s physical requirements, skaters may alter their eating patterns in unhealthful directions. This study assesses the eating attitudes and dietary intakes of elite adolescent female figure skaters to assess the potential nutritional risks among them.
Thirty-six elite competitive adolescent female figure skaters (mean age 16 ± 2.5 SD years) completed self-administered three-day records of dietary intake and simultaneous physical activity records during training season. Two months later, they attended a national training camp during which they completed the Eating Attitudes Test (EAT-40), provided fasting blood samples, and had heights and weights measured.
Participants’ mean body mass index (BMI) was 19.8 ± 2.1 SD. Their BMIs were within the normal range, and the majority (70%) did not report a history of recent weight loss. The mean EAT-40 score was normal (19.5 ± 13.5 SD) and below the cut-off score of 30 that indicates clinically significant eating pathology. However, one-quarter of the skaters had EAT-40 scores above 30. The skaters reported a mean energy intake of 1491 ± 471 SD kcal/day (31 ± 10 SD kcal/kg), with 61.6% of calories from carbohydrate, 14.6% from protein, and 23.7% from fat. Their reported dietary intakes were high in carbohydrates but low in total energy, fat, and bone-building nutrients.
Although these highly active young women compete in a sport that prizes leanness, they had appropriate weights. The athletes reported dietary intakes that were far below estimated energy needs and were at moderate risk of disordered eating. Anticipatory guidance is warranted to improve their dietary intakes, particularly of bone-building nutrients.
Eating attitudes; Female athletes; Disordered eating; EAT scores; Dietary intake; BMI
Increased interest in the potential societal benefit of incorporating health economics as a part of clinical translational science, particularly nutrition interventions, led the Office of Dietary Supplements at the National Institutes of Health to sponsor a conference to address key questions about economic analysis of nutrition interventions to enhance communication among health economic methodologists, researchers, reimbursement policy makers, and regulators. Issues discussed included the state of the science, such as what health economic methods are currently used to judge the burden of illness, interventions, or health care policies, and what new research methodologies are available or needed to address knowledge and methodological gaps or barriers. Research applications included existing evidence-based health economic research activities in nutrition that are ongoing or planned at federal agencies. International and U.S. regulatory, policy and clinical practice perspectives included a discussion of how research results can help regulators and policy makers within government make nutrition policy decisions, and how economics affects clinical guideline development.
cost-benefit analysis; primary prevention; nutrition policy; medical economics; nutrition therapy
To examine the relationship between adherence to prescribed folic acid supplements and folic acid intake, serum folate and plasma homocysteine in hemodialysis patients. The effects of change in adherence patterns from enrollment to one year later on changes in these same measures were also assessed.
Secondary data analysis
Eighty six hemodialysis patients who participated in the Hemodialysis (HEMO) Study’s Homocysteine ancillary study.
Main Outcome Measures
Folic acid supplement intake, serum folate and plasma homocysteine.
Eighty-eight percent of patients at enrollment and 91% one year later were adherent to prescribed folic acid supplements. Non-adherers had lower intakes of folic acid at both enrollment and one year later and lower serum folate levels at enrollment. Percent change was significantly different between the 3 adherence change groups for folic acid intake (p=0.001) and plasma homocysteine (p<0.001) from enrollment to one year later. The non-adherent group at enrollment had the lowest intakes and serum folate levels, and the highest plasma homocysteine levels. When they became adherent one year later, they had the greatest change in folic acid intake (5461%; p=0.03), coupled with a 69% increase in serum folate (p=0.04) and a 29% decrease in plasma homocysteine (p=0.03).
Hemodialysis patients who were non-adherent to folic acid supplement prescriptions had low folic acid intakes, low serum folates and high homocysteine levels. When their adherence improved, folic acid intakes rose, serum folates increased and plasma homocysteine levels decreased, although mild hyperhomocysteinemia persisted.
Adherence; folic acid; supplements; hemodialysis; homocysteine
folic acid; folate; NHANES; folic acid fortification
We reviewed lignan physiology and lignan intervention and epidemiological studies to determine if they decreased the risks of cardiovascular disease in Western populations. Five intervention studies using flaxseed lignan supplements indicated beneficial associations with C-reactive protein and a meta-analysis, which included these studies, also suggested a lowering effect on plasma total and low-density lipoprotein cholesterol. Three intervention studies using sesamin supplements indicated possible lipid and blood pressure lowering associations. Eleven human observational epidemiological studies examined dietary intakes of lignans in relation to cardiovascular disease risk. Five showed decreased risk with either increasing dietary intakes of lignans or increased levels of serum enterolactone (an enterolignan used as a biomarker of lignan intake), five studies were of borderline significance, and one was null. The associations between lignans and decreased risk of cardiovascular disease are promising, but are yet not well established, perhaps due to low lignan intakes in habitual Western diets. At the higher doses used in intervention studies, associations were more evident.
lignans; cardiovascular disease; review
online resources; government; dietary supplements; databases
To assess whether use of folic acid vitamin supplements reduces cardiac and stroke mortality in hemodialysis patients. Further, we examined whether consumption of folic acid from vitamin supplements greater than 1000 μg compared to standard 1000 μg, and 1000 μg compared to either lower dose or no consumption were associated with reduced cardiac and stroke mortality risk.
Secondary analysis of data from the Hemodialysis (HEMO) Study, a randomized clinical trial examining dialysis treatment regimens over three years follow-up. Participants: One thousand eight hundred and forty-six hemodialysis patients previously participating in the HEMO study.
Main Outcome Measure
Cardiac and stroke mortality.
From time-dependent Cox proportional hazard regression models, folic acid consumption from vitamin supplements, above or below the standard 1000 μg dose was not associated with decrease or increase in cardiac mortality (P = 0.53 above vs. standard dose and P = 0.46, below vs. standard dose). There was also no association between folic acid consumption and mortality from stroke (P = 0.27, above vs. standard dose and P = 0.64, below vs. standard dose).
Consumption of higher than the standard 1000 μg prescribed dose of folic acid was not beneficial in reducing cardiac or stroke mortality in hemodialysis patients. Similarly, consumption of lower than standard dose was not associated with an increase in either cardiac or stroke mortality.
Folic acid; cardiac; stroke; mortality; hemodialysis
Limited data are available on the source of usual nutrient intakes in the United States. This analysis aimed to assess contributions of micronutrients to usual intakes derived from all sources (naturally occurring, fortified and enriched, and dietary supplements) and to compare usual intakes to the Dietary Reference Intake for U.S. residents aged ≥2 y according to NHANES 2003–2006 (n = 16,110). We used the National Cancer Institute method to assess usual intakes of 19 micronutrients by source. Only a small percentage of the population had total usual intakes (from dietary intakes and supplements) below the estimated average requirement (EAR) for the following: vitamin B-6 (8%), folate (8%), zinc (8%), thiamin, riboflavin, niacin, vitamin B-12, phosphorus, iron, copper, and selenium (<6% for all). However, more of the population had total usual intakes below the EAR for vitamins A, C, D, and E (34, 25, 70, and 60%, respectively), calcium (38%), and magnesium (45%). Only 3 and 35% had total usual intakes of potassium and vitamin K, respectively, greater than the adequate intake. Enrichment and/or fortification largely contributed to intakes of vitamins A, C, and D, thiamin, iron, and folate. Dietary supplements further reduced the percentage of the population consuming less than the EAR for all nutrients. The percentage of the population with total intakes greater than the tolerable upper intake level (UL) was very low for most nutrients, whereas 10.3 and 8.4% of the population had intakes greater than the UL for niacin and zinc, respectively. Without enrichment and/or fortification and supplementation, many Americans did not achieve the recommended micronutrient intake levels set forth in the Dietary Reference Intake.
A higher body mass index is associated with better outcomes in hemodialysis patients; however, this index does not differentiate between fat and muscle mass. In order to clarify this, we examined the relationship between measures of fat and muscle mass and mortality in 1709 patients from the Hemodialysis Study. Triceps skin-fold thickness was used to assess body fat and mid-arm muscle circumference was used to assess muscle mass. Cox regression was used to evaluate the relationship between measures of body composition with all-cause mortality after adjustments for demographic, cardiovascular, dialysis, and nutrition-related risk factors. During a median follow-up of 2.5 years, there were 802 deaths. In adjusted models with continuous covariates, higher triceps skin-fold thickness and higher body mass index were significantly associated with decreased hazards of mortality, while higher mid-arm muscle circumference showed a trend toward decreased mortality. In adjusted models, lower quartiles of triceps skin-fold thickness, mid-arm muscle circumference, and body mass index were all significantly associated with higher all-cause mortality. These studies show that body composition in end-stage renal disease bears a complex relationship to all-cause mortality.
body mass index; dialysis; mortality; obesity
The NIH sponsored a scientific workshop, “Soy Protein/Isoflavone Research: Challenges in Designing and Evaluating Intervention Studies,” July 28–29, 2009. The workshop goal was to provide guidance for the next generation of soy protein/isoflavone human research. Session topics included population exposure to soy; the variability of the human response to soy; product composition; methods, tools, and resources available to estimate exposure and protocol adherence; and analytical methods to assess soy in foods and supplements and analytes in biologic fluids and other tissues. The intent of the workshop was to address the quality of soy studies, not the efficacy or safety of soy. Prior NIH workshops and an evidence-based review questioned the quality of data from human soy studies. If clinical studies are pursued, investigators need to ensure that the experimental designs are optimal and the studies properly executed. The workshop participants identified methodological issues that may confound study results and interpretation. Scientifically sound and useful options for dealing with these issues were discussed. The resulting guidance is presented in this document with a brief rationale. The guidance is specific to soy clinical research and does not address nonsoy-related factors that should also be considered in designing and reporting clinical studies. This guidance may be used by investigators, journal editors, study sponsors, and protocol reviewers for a variety of purposes, including designing and implementing trials, reporting results, and interpreting published epidemiological and clinical studies.
The mechanisms by which diet affects breast cancer (BC) risk are poorly understood but a positive relationship between fat and a negative association with fiber intake and BC risk have been demonstrated. Here we study the association between dietary fat/fiber ratio and estrogen metabolism. Fifty women were recruited, 22 were included in the low fat/high fiber and 22 were in the high fat/low fiber and 6 did not meet our criteria. Estrogens (determined in plasma, urine and feces) and dietary records were collected during 3 following days. All data were collected in winter and in summer. The high fat/low fiber group had significantly higher urinary total estrogens, estriol-3-glucuronide, 2-hydroxyestradiol, 16α-hydroxyestrone, and a higher 2-hydroxyestrone/4-hydroxyestrone ratio. Total fat intake correlated significantly with plasma estrone, estradiol, urinary 2-hydroxyestrone, 2-hydroxyestradiol, 2-hydroxyestrone/4-hydroxyestrone ratio, and total urinary estrogens, even after adjustment for total fiber intake. The high fat/low fiber diet was associated with high values both for catechol and 16α-hydroxylated estrogens and a high 2-hydroxyestrone/4-hydroxyestrone ratio, but 2-hydroxyestrone/16α-hydroxyestrone ratio was not different between the groups. Our results suggest that fat affects estrogen metabolism more than does fiber and that one mechanism resulting in high estrogen values is an increased reabsorption of biliary estrogens.
Diet; Estrogens; Breast cancer risk; Women