Nutritional Ketosis Defined by Diet, Urinary and Capillary Blood Measures

Abstract Objectives Tracking food and beverage intakes daily on a modified Ketogenic diet (MKD) pattern is time consuming, challenging and often, incomplete. The objective of this pre-post test design study was to examine different measures of nutritional ketosis in relation to reported dietary intakes before and during the adoption of the MKD for 8 days. Methods A sample of 19 adult women (mostly nutrition professionals) were instructed on a MKD, monitored foods and beverages consumed daily using the Carb Manager© app (Wombat Apps LLC, WA) and checked urinary ketones (Siemens Labstix Reagent Strips (Malvern, PA, USA)) each morning. On days 0, 7 and 8, participants fasted overnight and provided urine and capillary blood samples for determination of urinary acetoacetate (AoAc) and beta-hydroxybutyrate (BHB) concentrations, respectively. BHB concentrations were determined with device A, Precision Xtra (Alameda, CA, USA) and; device B, KetoMojo (Napa, CA, USA). Nutritional ketosis was defined as blood BHB ≥ 0.5 mmol/L or urinary AoAc ≥ 15 mg/dL. Descriptive statistics and correlations were run using SPSS version 23 (IBM Corp, 2015). Results At baseline, two-day averages of net carbohydrate (nCHO), energy, fiber, protein, and fat were as follows (median, (IQR)): 106 (81, 137); 1470 (1194, 1689); 11.8 (8.0,19.0); 64.2 (47.4, 80.6); and 67 (48, 78). All components except for energy are reported as grams/day. Baseline urinary AoAc concentrations were non-detectable; blood BHB by device A were 0.1 (0.1, 0.2) while device B were 0.1 (0.1, 0.1) mmol/L. Once on the MKD for 7 and 8 days, two-day averages of net carbohydrate (nCHO), energy, fiber, protein, and fat were as follows (median, (IQR)): 27 (25, 30); 1527 (1346, 1638); 18.2 (12.0, 22.2); 64.0 (49.9, 72.2); and 111 (95, 137). Day 8 urinary AoAc levels were 15 (5, 80) mg/dL while blood BHB were 0.6 (0.4, 1.3) with device A and 0.8 (0.3, 1.8) mmol/L with device B. Changes in nCHO intake were correlated with Day 8 BHB values (device A, rho = −0.655, P = 0.004 and device B, rho = −0.652, P = 0.005), and with urinary AoAc (rho = –0.631, P = 0.007). Conclusions All ketone biomarkers reflected changes in nCHO intake. Further study is warranted to confirm these observations and provide estimates of biomarker reliability to determine the most cost-effective method for assessing adherence to the MKD. Funding Sources Departmental.