Determinants and reference values for blood volume and total hemoglobin mass in women and men.

Blood volume (BV) is an important clinical parameter and is usually reported per kg of body mass (BM). When fat mass is elevated, this underestimates BV/BM. One aim was to study if differences in BV/BM related to sex, age, and fitness would decrease if normalized to lean body mass (LBM). The analysis included 263 women and 319 men (age: 10-93 years, body mass index: 14-41 kg/m2 ) and 107 athletes who underwent assessment of BV and hemoglobin mass (Hbmass ), body composition, and cardiorespiratory fitness. BV/BM was 25% lower (70.3 ± 11.3 and 80.3 ± 10.8 mL/kgBM ) in women than men, respectively, whereas BV/LBM was 6% higher in women (110.9 ± 12.5 and 105.3 ± 11.2 mL/kgLBM ). Hbmass /BM was 34% lower (8.9 ± 1.4 and 11.5 ± 11.2 g/kgBM ) in women than in men, respectively, but only 6% lower (14.0 ± 1.5 and 14.9 ± 1.5 g/kgLBM )/LBM. Age did not affect BV. Athlete's BV/BM was 17.2% higher than non-athletes, but decreased to only 2.5% when normalized to LBM. Of the variables analyzed, LBM was the strongest predictor for BV (R2 = .72, p < .001) and Hbmass (R2 = .81, p < .001). These data may only be valid for BV/Hbmass when assessed by CO re-breathing. Hbmass /LBM could be considered a valuable clinical matrix in medical care aiming to normalize blood homeostasis.

Greater blood volume and Hb mass in obese women quantified by the carbon monoxide-rebreathing method affects interpretation of iron biomarkers and iron requirements.

BACKGROUND/OBJECTIVE: Iron deficiency (ID) is common in overweight and obese individuals (OW/OB) but the mechanism is uncertain. Greater blood volume (BV) in OW/OB may increase hemoglobin (Hb) mass and iron requirements, and confound iron biomarkers by hemodilution. Quantification of BV/PV changes in OW/OB is challenging and a formula to estimate BV/PV based on anthropometric indices would be valuable. In normal weight (NW) and OW/OB women, we aimed at: (1) measure BV and assess whether differences in BV affect concentrations and total circulating mass of Hb and iron biomarkers; (2) develop an algorithm describing BV in OW/OB. SUBJECTS/METHODS: In a cross-sectional study, we measured BV in NW, OW, and OB non-anemic women (n = 62) by using the carbon monoxide-rebreathing method, body composition by dual energy X-ray absorptiometry, and iron and inflammatory status. RESULTS: OW and OB women had 11 and 16% higher mean BV and PV compared to NW (P < 0.05), respectively. In OW/OB compared to NW, total circulating masses of IL-6, hepcidin, Hb, and sTfR were higher, while total mass of serum iron was lower (for all, P < 0.05). An equation including height, body mass and lean mass to estimate BV in all BMI groups (R2 = 0.76). CONCLUSION: An equation based on anthropometric indices provides a good estimate of increased BV in OW/OB women. In OW/OB women, there is an increase in Hb mass that likely increases iron requirements for erythropoiesis and circulating TfR mass. At the same time, higher hepcidin concentrations may lower serum iron mass. Both these mechanisms may increase risk for ID in OW/OB women.

Maternal iron kinetics and maternal-fetal iron transfer in normal-weight and overweight pregnancy.

BACKGROUND: Inflammation during pregnancy may aggravate iron deficiency (ID) by increasing serum hepcidin and reducing iron absorption. This could restrict iron transfer to the fetus, increasing risk of infant ID and its adverse effects. OBJECTIVES: We aimed to assess whether iron bioavailability and/or iron transfer to the fetus is impaired in overweight/obese (OW) pregnant women with adiposity-related inflammation, compared with normal-weight (NW) pregnant women. METHODS: In this prospective study, we followed NW (n = 43) and OW (n = 40) pregnant women who were receiving iron supplements from the 14th week of gestation to term and followed their infants to age 6 mo. We administered 57Fe and 58Fe in test meals mid-second and mid-third trimester, and measured tracer kinetics throughout pregnancy and infancy. RESULTS: In total, 38 NW and 36 OW women completed the study to pregnancy week 36, whereas 30 NW and 27 OW mother-infant pairs completed the study to 6 mo postpartum. Both groups had comparable iron status, hemoglobin, and serum hepcidin throughout pregnancy. Compared with the NW, the OW pregnant women had 1) 43% lower fractional iron absorption (FIA) in the third trimester (P = 0.033) with median [IQR] FIA of 23.9% [11.4%-35.7%] and 13.5% [10.8%-19.5%], respectively; and 2) 17% lower maternal-fetal iron transfer from the first tracer (P = 0.051) with median [IQR] maternal-fetal iron transfer of 4.8% [4.2%-5.4%] and 4.0% [3.6%-4.6%], respectively. Compared with the infants born to NW women, infants born to OW women had lower body iron stores (BIS) with median [IQR] 7.7 [6.3-8.8] and 6.6 [4.6-9.2] mg/kg body weight at age 6 mo, respectively (P = 0.024). Prepregnancy BMI was a negative predictor of maternal-fetal iron transfer (ß = -0.339, SE = 0.144, P = 0.025) and infant BIS (ß = -0.237, SE = 0.026, P = 0.001). CONCLUSIONS: Compared with NW, OW pregnant women failed to upregulate iron absorption in late pregnancy, transferred less iron to their fetus, and their infants had lower BIS. These impairments were associated with inflammation independently of serum hepcidin.This trial was registered at clinicaltrials.gov as NCT02747316.

How Having a Clear Why Can Help Us Cope With Almost Anything: Meaningful Well-Being and the COVID-19 Pandemic in México.

Background: Coronavirus disease 2019 (COVID-19) has resulted in an increase in known risk factors for mental health problems. Mexico adopted lockdown and physical distancing as a containment strategy with potential consequences on day to day life, such as social isolation, loss of income and loneliness that can have important consequences in terms of mental health. Objective: We aimed to examine the effect of the initial phases of the COVID-19 pandemic on psychological distress, well-being and perceived physical health among Mexican-base respondents and to examine whether coping strategies would play a potential intermediating role in relation to these variables. Under the Existential Positive Psychology perspective, an emphasis was made on meaning-centered coping. Methods: A cross-sectional study was conducted between April 30 and June 16th 2020 among 604 Mexicans-base respondents of which 471 were women and 132 men. Data was collected by using online questionnaires. Psychological distress was measured using the Depression, Anxiety, and Stress Scale (DASS-21). The Brief COPE Inventory was used to assess problem-focused and emotion-focused coping strategies. We also used the Meaning-Centered Coping Scale (MCCS). PERMA-Profiler was used to assess well-being, perceived physical health, and loneliness. Profiler and Descriptive analyses and bivariate linear regression were performed to examine the association of variables. Results: 45.9% of the participants reported moderate to extremely severe psychological distress. Our results demonstrate that problem-focused and emotion-focused coping were positively related to psychological distress, whereas meaning-centered coping was negatively associated with distress. Furthermore, psychological distress played a potential negative role in the perceived physical health, while meaning-centered coping and well-being buffered the negative influence of psychological distress on perceived physical health (completely standardized indirect effect = -0.01, SE: 0.012, 95% CI [-0.065; -0.017]. Conclusion: Meaning-centered coping was found to suppress the negative influence of psychological distress on sensation of decreased physical health corroborating the critical role of meaning in life in promoting well-being. Future studies can further examine the value of the critical role of meaning in life in promoting well-being as a protective factor against severe distress during traumatic events. Findings of this study can be used to orient policies and interventions aimed to alleviate suffering in the midst of the COVID-19 pandemic.

Does obesity increase risk for iron deficiency? A review of the literature and the potential mechanisms.

Increasing obesity is a major global health concern while at the same time iron-deficiency anemia remains common worldwide. Although these two conditions represent opposite ends of the spectrum of over- and under-nutrition, they appear to be linked: overweight individuals are at higher risk of iron deficiency than normal-weight individuals. Potential explanations for this association include dilutional hypoferremia, poor dietary iron intake, increased iron requirements, and/or impaired iron absorption in obese individuals. Recent evidence suggests obesity-related inflammation may play a central role through its regulation of hepcidin. Hepcidin levels are higher in obese individuals and are linked to subclinical inflammation; this may reduce iron absorption and blunt the effects of iron fortification. Thus, low iron status in overweight individuals may result from a combination of nutritional (reduced absorption) and functional (increased sequestration) iron deficiency. In this review, we focus on subclinical inflammation in obesity, and its effect on hepcidin levels, as the most plausible explanation for the link between iron deficiency and obesity.

Time Trends in Age at Menarche and Related Non-Communicable Disease Risk during the 20th Century in Mexico.

Developed countries have shown a time trend towards a younger age at menarche (AAM), which is associated with increased risk of later obesity and non-communicable diseases. This study aimed to assess whether a time trend in AAM is associated with disease risk in Mexican women (n = 30,826), using data from the Mexican National Health Survey (2000). Linear and log binomial regression was used for nutritional and disease outcomes, while Welch⁻ANOVA was used to test for a time trend. AAM (in years) decreased over time (p < 0.001), with a maximal difference of 0.99 years between the 1920s (13.6 years) and 1980s (12.6 years ). AAM was negatively associated with weight (ß = -1.01 kg; 95% CI -1.006, -1.004) and body mass index (BMI) (ß = -1.01 kg/m²; -1.007, -1.006), and positively with height (ß = 0.18 cm; 0.112, 0.231). AAM was associated with diabetes (RR = 0.95; 0.93, 0.98) and hypercholesterolemia (RR = 0.93; 0.90, 0.95), but not with hypertension, breast cancer or arthritis. In Mexico, AAM decreased significantly during the 20th century. AAM was inversely associated with adult weight and BMI, and positively with height. Women with a later AAM had a lower risk of diabetes and hypercholesterolemia.

The effects of fat loss after bariatric surgery on inflammation, serum hepcidin, and iron absorption: a prospective 6-mo iron stable isotope study.

BACKGROUND: Iron deficiency is common in obese subjects. This may be due to an increase in serum hepcidin and a decrease in iron absorption from adiposity-related inflammation. OBJECTIVE: We evaluated whether weight and fat loss in obese subjects would decrease inflammation and serum hepcidin and thereby improve iron absorption. DESIGN: We performed a 6-mo prospective study in obese [body mass index (in kg/m2) ≥35 and <45] adults who had recently undergone laparoscopic sleeve gastrectomy. At 2 and 8 mo postsurgery, subjects consumed a test drink with 6 mg 57Fe as ferrous sulfate and were intravenously infused with 100 µg 58Fe as iron citrate. We then compared erythrocyte incorporation of iron isotopic labels, changes in body composition, iron status, hepcidin, and inflammation at each time point. RESULTS: Forty-three subjects were studied at baseline, and 38 completed the protocol (32 women and 6 men). After 6 mo, total body fat, interleukin IL-6, and hepcidin were significantly lower (all P < 0.005). In iron-deficient subjects (n = 17), geometric mean (95% CI) iron absorption increased by 28% [from 9.7% (6.5%, 14.6%) to 12.4% (7.7%, 20.1%); P = 0.03], whereas in iron-sufficient subjects (n = 21), absorption did not change [5.9% (4.0%, 8.6%) and 5.6% (3.9%, 8.2%); P = 0.81]. CONCLUSION: Adiposity-related inflammation is associated with a reduction in the normal upregulation of iron absorption in iron-deficient obese subjects, and this adverse effect may be ameliorated by fat loss. This protocol was approved by the ethics committees of Wageningen University, ETH Zurich, the University of Monterrey, and the Federal Commission for the Protection against Sanitary Risks, and registered at clinicaltrials.gov as NCT01347905.

In overweight and obese women, dietary iron absorption is reduced and the enhancement of iron absorption by ascorbic acid is one-half that in normal-weight women.

BACKGROUND: Iron deficiency is common in overweight and obese individuals. This deficiency may be due to adiposity-related inflammation that increases serum hepcidin and decreases dietary iron absorption. Because hepcidin reduces iron efflux from the basolateral enterocyte, it is uncertain whether luminal enhancers of dietary iron absorption such as ascorbic acid can be effective in overweight and obese individuals. OBJECTIVE: In this study, we compared iron absorption from a meal with ascorbic acid (+AA) and a meal without ascorbic acid (-AA) in women in a normal-weight group (NW) with those in overweight and obese groups combined (OW/OB). DESIGN: Healthy, nonanemic women [n = 62; BMI (in kg/m(2)): 18.5-39.9] consumed a stable-isotope-labeled wheat-based test meal -AA and a wheat-based test meal +AA (31.4 mg ascorbic acid). We measured iron absorption and body composition with the use of dual-energy X-ray absorptiometry, blood volume with the use of a carbon monoxide (CO)-rebreathing method, iron status, inflammation, and serum hepcidin. RESULTS: Inflammatory biomarkers (all P < 0.05) and hepcidin (P = 0.08) were lower in the NW than in the OW/OB. Geometric mean (95% CI) iron absorptions in the NW and OW/OB were 19.0% (15.2%, 23.5%) and 12.9% (9.7%, 16.9%) (P = 0.049), respectively, from -AA meals and 29.5% (23.3%, 38.2%) and 16.6% (12.8%, 21.7%) (P = 0.004), respectively, from +AA meals. Median percentage increases in iron absorption for -AA to +AA meals were 56% in the NW (P < 0.001) and 28% in OW/OB (P = 0.006). Serum ferritin [R(2) = 0.22; ß = -0.17 (95% CI: -0.25, -0.09)], transferrin receptor [R(2) = 0.23; ß = 2.79 (95% CI: 1.47, 4.11)], and hepcidin [R(2) = 0.13; ß = -0.85 (95% CI: -1.41, -0.28)] were significant predictors of iron absorption. CONCLUSIONS: In overweight and obese women, iron absorption is two-thirds that in normal-weight women, and the enhancing effect of ascorbic acid on iron absorption is one-half of that in normal-weight women. Recommending higher intakes of ascorbic acid (or other luminal enhancers of iron absorption) in obese individuals to improve iron status may have a limited effect. This trial was registered at clinicaltrials.gov as NCT01884506.

Sharply higher rates of iron deficiency in obese Mexican women and children are predicted by obesity-related inflammation rather than by differences in dietary iron intake.

BACKGROUND: Obese individuals may be at increased risk of iron deficiency (ID), but it is unclear whether this is due to poor dietary iron intakes or to adiposity-related inflammation. OBJECTIVE: The aim of this study was to examine the relations between body mass index (BMI), dietary iron, and dietary factors affecting iron bioavailability, iron status, and inflammation [C-reactive protein (CRP)] in a transition country where obesity and ID are common. DESIGN: Data from the 1999 Mexican Nutrition Survey, which included 1174 children (aged 5-12 y) and 621 nonpregnant women (aged 18-50 y), were analyzed. RESULTS: The prevalence of obesity was 25.3% in women and 3.5% in children. The prevalence of ID was significantly (P < 0.05) higher in obese women and children compared with normal-weight subjects [odds ratios (95% CIs): 1.92 (1.23, 3.01) and 3.96 (1.34, 11.67) for women and children, respectively]. Despite similar dietary iron intakes in the 2 groups, serum iron concentrations were lower in obese women than in normal-weight women (62.6 ± 29.5 compared with 72.4 ± 34.6 µg/dL; P = 0.014), and total-iron-binding capacity was higher in obese children than in normal-weight children (399 ± 51 compared with 360 ± 48 µg/dL; P < 0.001). CRP concentrations in obese women and children were 4 times those of their normal-weight counterparts (P < 0.05). CRP but not iron intake was a strong negative predictor of iron status, independently of BMI (P < 0.05). CONCLUSIONS: The risk of ID in obese Mexican women and children was 2-4 times that of normal-weight individuals at similar dietary iron intakes. This increased risk of ID may be due to the effects of obesity-related inflammation on dietary iron absorption. Thus, ID control efforts in Mexico may be hampered by increasing rates of adiposity in women and children.