Jennifer L. Bedford

A Prospective Exploration of Cognitive Dietary Restraint, Subclinical Ovulatory Disturbances, Cortisol, and Change in Bone Density over Two Years in Healthy Young Women

CONTEXT Cross-sectional studies have found associations among elevated cognitive dietary restraint (CDR), increased ovulatory disturbances, and lower bone mass, possibly mediated by cortisol. OBJECTIVE To determine whether healthy young women with higher CDR have more menstrual cycles with subclinical ovulatory disturbances (SOD), elevated 24-h urinary free cortisol (UFC), and less positive 2-yr areal bone mineral density change (Delta-aBMD). DESIGN, SETTING, AND PARTICIPANTS We conducted a 2-yr longitudinal study of 123 healthy, community-dwelling, nonobese, regularly menstruating women aged 19-35 yr. MAIN OUTCOME MEASURES Key variables were Three Factor Eating Questionnaire Restraint score, percent of cycles with anvoluation and/or luteal phase length <10 d (%SOD), UFC, and Delta-aBMD at the lumbar spine (L1-L4), total hip, and whole body. Anthropometrics, general stress, physical activity, and energy intake were measured. Adjusting for potential confounders, differences were examined by general linear modeling using median split of CDR score and %SOD. RESULTS Women with higher CDR had higher %SOD (56 vs. 34%, P < 0.001) and higher UFC (28.0 vs. 24.0 microg/d, P = 0.021). Delta-aBMD did not differ by CDR. Women with higher %SOD had less positive Delta-aBMD at L1-L4 (0.7 vs. 1.9%, P = 0.034) and hip (-0.6 vs. 0.9%, P = 0.001), and higher CDR score (8.7 vs. 7.1, P = 0.04). Physical activity, general stress, body mass index, and energy intake did not explain differences by CDR or %SOD. UFC was not associated with %SOD or Delta-aBMD. CONCLUSION Women with more frequent SOD reported higher CDR and experienced less positive Delta-aBMD. Although women with higher CDR had higher UFC, the mechanism linking CDR, SOD, and aBMD is not clear.

Higher Urinary Sodium, a Proxy for Intake, Is Associated with Increased Calcium Excretion and Lower Hip Bone Density in Healthy Young Women with Lower Calcium Intakes

We assessed 24-h urinary sodium (Na) and its relationship with urinary calcium (Ca) and areal bone mineral density (aBMD) at the whole body, lumbar spine and total hip in a cross-sectional study. 102 healthy non-obese women completed timed 24-h urine collections which were analyzed for Na and Ca. Dietary intakes were estimated using a validated food frequency questionnaire. Participants were grouped as those with lower vs. higher calcium intake by median split (506 mg/1000 kcal). Dietary Na intake correlated with 24-h urinary loss. Urinary Na correlated positively with urinary Ca for all participants (r = 0.29, p < 0.01) and among those with lower (r = 0.37, p < 0.01) but not higher calcium intakes (r = 0.19, p = 0.19). Urinary Na was inversely associated with hip aBMD for all participants (r = −0.21, p = 0.04) and among women with lower (r = −0.36, p < 0.01) but not higher (r = −0.05, p = 0.71) calcium intakes. Urinary Na also entered a regression equation for hip aBMD in women with lower Ca intakes, contributing 5.9% to explained variance. In conclusion, 24-h urinary Na (a proxy for intake) is associated with higher urinary Ca loss in young women and may affect aBMD, particularly in those with lower calcium intakes.

The relationship between 24-h urinary cortisol and bone in healthy young women.

BackgroundCortisol within the normal range has been associated with reduced bone density in the elderly, but little is known about this relationship in healthy young women.PurposeThe purpose of this study is to assess whether 24-h urinary free cortisol excretion (UFC) is related to bone density in 132 healthy, non-obese, regularly menstruating women, aged 19–35.MethodParticipants completed questionnaires (food frequency, demographics, physical activity, dietary restraint, perceived stress, and daily stress) and a 24-h urine collection. UFC was determined by high-throughput liquid chromatography and tandem mass spectrometry. Anthropometrics were completed and a dual energy X-ray absorptiometry scan measured areal bone mineral density (aBMD, g/cm2) and bone mineral content (BMC, g) at the lumbar spine (L1–4), hip, and total body (TB) as well as total body lean (LBM) and fat mass.ResultsaBMD and BMC were significantly positively associated with height, LBM, physical activity, calcium intake, and duration of previous oral contraceptive use (except L1–4) and negatively with perceived stress. UFC was not correlated with any measured variables except urine volume (r = 0.17, p = 0.046). After adjusting for urine volume, height, LBM, ethnicity, and prior oral contraceptive use, UFC was significantly inversely associated with TB BMC (r = −0.30, p < 0.001) and aBMD (r = −0.27, p = 0.003), L1–4 aBMD (r = −0.19, p = 0.035) and BMC (r = −0.18, p = 0.049), and hip BMC (r = −0.23, p = 0.011). Further adjustment for sport activity, calcium intake and perceived stress did not change these relationships meaningfully except that L1–4 became nonsignificant (p < 0.07).ConclusionCortisol within the normal range appears to have a minor negative influence on bone density in healthy young women.

Detecting evidence of luteal activity by least-squares quantitative basal temperature analysis against urinary progesterone metabolites and the effect of wake-time variability

OBJECTIVE To assess computerised least-squares analysis of quantitative basal temperature (LS-BT) against urinary pregnanediol glucuronide (PdG) as an indirect measure of ovulation, and to evaluate the stability of LS-QBT to wake-time variation. STUDY DESIGN Cross-sectional study of 40 healthy, normal-weight, regularly menstruating women aged 19-34. Participants recorded basal temperature and collected first void urine daily for one complete menstrual cycle. Evidence of luteal activity (ELA), an indirect ovulation indicator, was assessed using Kassams PdG algorithm, which identifies a sustained 3-day PdG rise, and the LS-QBT algorithm, by determining whether the temperature curve is significantly biphasic. Cycles were classified as ELA(+) or ELA(-). We explored the need to pre-screen for wake-time variations by repeating the analysis using: (A) all recorded temperatures, (B) wake-time adjusted temperatures, (C) temperatures within 2h of average wake-time, and (D) expert reviewed temperatures. RESULTS Relative to PdG, classification of cycles as ELA(+) was 35 of 36 for LS-QBT methods A and B, 33 of 34 (method C) and 30 of 31 (method D). Classification of cycles as ELA(-) was 1 of 4 (methods A and B) and 0 of 3 (methods C and D). Positive predictive value was 92% for methods A-C and 91% for method D. Negative predictive value was 50% for methods A and B and 0% for methods C and D. Overall accuracy was 90% for methods A and B, 89% for method C and 88% for method D. The day of a significant temperature increase by LS-QBT and the first day of a sustained PdG rise were correlated (r=0.803, 0.741, 0.651, 0.747 for methods A-D, respectively, all p<0.001). CONCLUSION LS-QBT showed excellent detection of ELA(+) cycles (sensitivity, positive predictive value) but poor detection of ELA(-) cycles (specificity, negative predictive value) relative to urinary PdG. Correlations between the methods and overall accuracy were good and similar for all analyses. Findings suggest that LS-QBT is robust to wake-time variability and that expert interpretation is unnecessary. This method shows promise for use as an epidemiological tool to document cyclic progesterone increase. Further validation relative to daily transvaginal ultrasound is required.

Negative eating and body attitudes are associated with increased daytime ambulatory blood pressure in healthy young women

BACKGROUND AND OBJECTIVE Various psychosocial stressors have been associated with increased ambulatory blood pressure (ABP) and cortisol in middle-aged women. Given that many young women report negative eating/body attitudes, we examined whether these attitudes were associated with cortisol and ABP in a cross-sectional study. METHODS 120 non-obese, healthy women aged 19-35 completed questionnaires, measurement of 24-h urinary free cortisol (UFC), and 12-h daytime ABP. Main and interactive effects of eating/body attitudes (average Z-score of Eating/body attitude questionnaires split at zero) and current weight loss effort (yes/no) were examined by General Linear Modeling adjusted for covariates. RESULTS Women with negative eating/body attitudes were more likely to report current weight loss attempts (63% versus 21%, p<0.001). Eating/body attitudes or weight loss effort did not have main or interactive effects on age, physical activity level, energy intakes, general stress (average Z-score of psychosocial stress questionnaires) or UFC. Body mass index was higher among those currently trying to lose weight but did not differ by eating/body attitudes. Significant main effects of eating/body attitudes were detected on ABP: diastolic ABP (73.2 ± 0.7 versus 70.3 ± 0.8mm Hg, p=0.011) and mean arterial pressure (87.3 ± 0.7 versus 84.9 ± 0.8mm Hg, p=0.032) were higher among women with negative versus neutral/positive eating/body attitudes. There were no weight loss effort main effects for ABP, or weight loss effort-by-Eating/body attitude interactions. CONCLUSION This exploratory study suggests that more negative eating/body-related attitudes may be modestly associated with higher ABP independent of weight loss effort.