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BackgroundFreezing and thawing of milk alters a number of assay values and a practical perspective for osmolality is needed.ObjectivesTo determine the consistency of osmolality values in human milk (Mosm) after varying frozen storage‐time and thawing protocols.Methods14 lactating women gave a 1st full‐breast expression after 90 min of nursing abstinence and 11 returned within a wk for a 2nd extraction. 3 aliquots were stored at ‐20oC: 1st brought to 21°C and measured within 1 wk; 2nd with same procedure ~10‐11 wks later; and 3rd warmed to 37oC in a water bath and then cooled to 21oC also at this later time. Single milk collections from 16 additional women were analyzed at the final time‐point by both thawing routines. Mosm was determined on a Vogel Löser 815 osmometer and expressed as mOsm/kg.ResultsFor the subgroup of 25 samples measured twice after standard thawing (early and late), the respective Mosm medians were 288 mOsm/kg and 309 mOsm/kg (p=<0.001, Wilcoxon test). The Pearson r‐value was 0.772 (p=<0.001). This is consistent with the typical osmolality of ~300 mOsm/kg. The overall descriptive Mosm median for the 46 milk specimens measured after simple thawing was 308 mOsm/kg compared to 304 mOsm/kg; this 1.3% difference was significant (p=0.011). The Pearson correlation coefficient was r=0.847 (p=<0.001). 85% of values were within a band of ±5% of the median.ConclusionMinor variations in storage and handling produce significant, but not practically meaningful, differences for osmolality research with human milk.

Background: It has been demonstrated that human milk osmolality (Mosm) is regulated within an established range, typically 290 to 300 mOsm/kg, and appears to be resistant to effects of maternal dehydration, as refl ected by high urinary osmolality (Uosm). Objective: To determine the degree of association between Mosm and Uosm at a common point in time, as well as the reproducibility of both measures over a one-week interval of sampling. Methods: Mosm and Uosm were measured with a Vogel Löser 450 osmometer on samples of the respective biological fl uids collected concurrently in 31 lactating women, with infants aged between 30 and 340 days. In the fi rst 15 women recruited, collections were repeated 7 days after the initial ones. Results: The median Mosm for the 46 samples collected was 308 mOsm/kg with a range from 288 to 448 mOsm/kg. The corresponding values for Uosm were 598 mOsm/kg with a range from 93 to 1,678 mOsm/kg. The Spearman rank-order correlation coeffi cient for within-individual association of Mosm and Uosm was r = 0.214 (p = 0.153). The median Mosm for the 15 repeat-subjects was 309 mOsm/kg on both occasions, with a within-individual Spearman coeffi cient of r = 0.326 (p = 0.118). By contrast, for the Uosm, the within-subject association was much stronger, with r = 0.699 (p = 0.002). Conclusions: The osmometry technique proved to be a highly stable and reproducible measurement technique. Mosm and Uosm are not signifi cantly associated at a point in time. Intra-subject Mosm varies more across time than intra-subject Uosm.

BackgroundHuman plasma osmolality is tightly regulated in the 275 – 295 mOsm/kg range and breast milk osmolality (Mosm) oscillates through a slightly higher range. Studies in dairy cows demonstrate an influence of systemic hydration on bovine MosmObjectiveTo describe hydration status in lactating women and explore any relation with MosmMethods31 low‐ and middle‐income women gave a full‐breast expression after 90 min of nursing abstinence along with a concurrent spot sample of urine, 15 of whom repeated ~7 days later. Milk volume (Mvol) was measured and aliquots of urine and milk stored from 1 to 12 wks. Osmolality was determined in both fluids using a Vogel, Löser 815 osmometer expressed as mOsm/kg. Data were analyzed using SPSS version 20ResultsThe Mvol ranged from 2‐100 mL, and Mosm from 288‐448 mOsm/kg, whereas Uosm ranged from 93‐1678 mOsm/kg. Nevertheless, the Spearmann rank‐order correlation coefficient was r=0.214 (p=0.153) [n=46]; Mosm was not associated with maternal age r=0.243 (p=0.104), nor with lactation age r= ‐0.280 (p=0.060). Pearson correlation for repeat Mosm was r=0.204 (p=0.233) and for Uosm was r=0.642 (p=0.005) [n=15]ConclusionsLactating women have higher Uosm than other sectors in Western Guatemala. Mosm is not associated with systemic hydration as reflected by Uosm. There is a high association of systemic hydration status on repeated measurementSupported byThe European Hydration Institute, Madrid, Spain; Fundación Iberoamericana de Nutricion, Granada, Spain; and Hildegard Grunow Foundation, Munich, Germany

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BackgroundMeasures of the community nutrition environment are important to understanding the food environment, which affects individual diet.ObjectiveTo develop a formal protocol to improve the reliability of using direct observation to map the food environment in Guatemala.MethodsFour teams of two raters were asked to walk two thoroughfares in urban Quetzaltenango, Guatemala. Each team consisted of one rater from Guatemala and one non‐Guatemalan. All teams read the mapping protocol and explored the area prior to mapping. Data was collected in a step‐wise fashion. The first team collected data and revised the mapping protocol that was then utilized by the next team. The validity of direct observation in mapping a community food environment in Quetzaltenango was determined by comparing the inter‐team concordance on each subsequent use of the protocol; and compared to data previously collected without a protocol.ResultsThe inter‐team reliability improved with the use of a formal protocol and mixed‐ethnicity teams. On one street, the inter‐team reliability improved to 76% using the revised protocol from 67% with the original protocol; compared to 60% without a protocol. On the other street in which 40% of the food establishments were mobile vendors, the improvement in inter‐team reliability was modest.ConclusionsIn Guatemala, street‐mapping correspondence saturates at a certain point with or without considering the ambulatory aspects of carts and street vendors. A formal protocol and mixed teams that include a rater native to the country of interest improve the use of direct observation as a reliable low‐cost method to map the community food environment.