Biomarker-predicted sugars intake compared with self-reported measures in US Hispanics/Latinos: results from the HCHS/SOL SOLNAS study.

OBJECTIVE: Measurement error in self-reported total sugars intake may obscure associations between sugars consumption and health outcomes, and the sum of 24 h urinary sucrose and fructose may serve as a predictive biomarker of total sugars intake. DESIGN: The Study of Latinos: Nutrition & Physical Activity Assessment Study (SOLNAS) was an ancillary study to the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) cohort. Doubly labelled water and 24 h urinary sucrose and fructose were used as biomarkers of energy and sugars intake, respectively. Participants' diets were assessed by up to three 24 h recalls (88 % had two or more recalls). Procedures were repeated approximately 6 months after the initial visit among a subset of ninety-six participants. SETTING: Four centres (Bronx, NY; Chicago, IL; Miami, FL; San Diego, CA) across the USA. SUBJECTS: Men and women (n 477) aged 18-74 years. RESULTS: The geometric mean of total sugars was 167·5 (95 % CI 154·4, 181·7) g/d for the biomarker-predicted and 90·6 (95 % CI 87·6, 93·6) g/d for the self-reported total sugars intake. Self-reported total sugars intake was not correlated with biomarker-predicted sugars intake (r=-0·06, P=0·20, n 450). Among the reliability sample (n 90), the reproducibility coefficient was 0·59 for biomarker-predicted and 0·20 for self-reported total sugars intake. CONCLUSIONS: Possible explanations for the lack of association between biomarker-predicted and self-reported sugars intake include measurement error in self-reported diet, high intra-individual variability in sugars intake, and/or urinary sucrose and fructose may not be a suitable proxy for total sugars intake in this study population.

Checking for completeness of 24-h urine collection using para-amino benzoic acid not necessary in the Observing Protein and Energy Nutrition study.

BACKGROUND/OBJECTIVES: The orally administered para-amino benzoic acid (PABA) is known to have near 100% excretion in urine and is used as a measure of 24-h urine collection completeness (referred to as PABAcheck). The purpose was to examine the effect of including urine collections deemed incomplete based on PABAcheck in a dietary measurement error study. SUBJECTS/METHODS: The Observing Protein and Energy Nutrition (OPEN) study was conducted in 1999-2000 and included 484 men and women aged 40-69 years. A food frequency questionnaire and 24-h dietary recalls were evaluated using recovery biomarkers that included urinary nitrogen and potassium from two 24-h urine collections. Statistical modeling determined the measurement error properties of dietary assessment instruments. In the original analyses, PABAcheck was used as a measure of complete urine collection; incomplete collections were either excluded or adjusted to acceptable levels. The OPEN data were reanalyzed including all urine collections and by using criteria based on self-reported missing voids to assess the differences. RESULTS: Means and coefficients of variation for biomarker-based protein and potassium intakes, and measurement error model-based correlations and attenuation factors were similar regardless of whether PABAcheck or missed voids were considered. CONCLUSION: PABAcheck may not be required in large population-based biomarker studies. However, until there are more analyses evaluating the necessity of a PABAcheck, it is recommended that PABA be given to all participants, but not necessarily analyzed. Then, PABAcheck could be used selectively as a marker of completeness among the collections in which low levels of biomarker are detected or for which noncompliance is suspected.

The diet-body offset in human nitrogen isotopic values: a controlled dietary study.

The "trophic level enrichment" between diet and body results in an overall increase in nitrogen isotopic values as the food chain is ascended. Quantifying the diet-body Δ(15) N spacing has proved difficult, particularly for humans. The value is usually assumed to be +3-5‰ in the archaeological literature. We report here the first (to our knowledge) data from humans on isotopically known diets, comparing dietary intake and a body tissue sample, that of red blood cells. Samples were taken from 11 subjects on controlled diets for a 30-day period, where the controlled diets were designed to match each individual's habitual diet, thus reducing problems with short-term changes in diet causing isotopic changes in the body pool. The Δ(15) N(diet-RBC) was measured as +3.5‰. Using measured offsets from other studies, we estimate the human Δ(15) N(diet-keratin) as +5.0-5.3‰, which is in good agreement with values derived from the two other studies using individual diet records. We also estimate a value for Δ(15) N(diet-collagen) of ≈6‰, again in combination with measured offsets from other studies. This value is larger than usually assumed in palaeodietary studies, which suggests that the proportion of animal protein in prehistoric human diet may have often been overestimated in isotopic studies of palaeodiet.

Urinary sugars biomarker relates better to extrinsic than to intrinsic sugars intake in a metabolic study with volunteers consuming their normal diet.

BACKGROUND/OBJECTIVES: Sugars in diet are very difficult to measure because of the unreliability of self-reported dietary intake. Sucrose and fructose excreted in urine have been recently suggested as a biomarker for total sugars intake. To further characterize the use of this biomarker, we investigated whether urinary sugars correlated better to extrinsic compared to intrinsic sugars in the diet. SUBJECTS/METHODS: Seven male and six female healthy participants were living for 30 days in a metabolic suite under strictly controlled conditions consuming their usual diet as assessed beforehand from four consecutive 7-day food diaries kept at home. During the 30-day study, all 24 h urine specimens were collected, validated for their completeness and analysed for sucrose and fructose. RESULTS: The mean total sugars intake in the group was 202+/-69 g day(-1). Daily intake of extrinsic, intrinsic and milk sugars contributed 60.1, 34.4 and 5.5%, to the total sugars intake, respectively. The individuals' 30-day mean sugars excretion levels were significantly correlated with the 30-day means of extrinsic sugars (r=0.84; P<0.001) but not with the intrinsic sugars intake (r=0.43; P=0.144). In the regression, only extrinsic sugars intake explained a significant proportion of the variability in sugars excretion (adjusted R(2)=0.64; P=0.001); daily excretion of 100 mg sucrose and fructose in urine predicted 124 g of extrinsic total sugars in the diet. Using fewer urinary and dietary measurements in the analysis did not change the overall trend of the findings. CONCLUSIONS: In this group of volunteers, sucrose and fructose in urine better correlated to extrinsic than to intrinsic sugars intake.

Twenty-four-hour urinary thiamine as a biomarker for the assessment of thiamine intake.

OBJECTIVE: To investigate 24-h urinary thiamine as a potential biomarker for thiamine intake for use in validation studies to assess the validity of dietary intake data collected by self-reporting dietary methods. SUBJECTS: Seven male and six female healthy participants living for 30 days in a metabolic suite under strictly controlled conditions consuming their usual diet as assessed beforehand from four consecutive 7-day food diaries kept at home. During the 30-day study, all 24-h urine specimens were collected, validated for their completeness and analysed for thiamine. RESULTS: Thirty-day mean (+/-s.d.) calculated thiamine intake was 2.22+/-0.55 mg/day. Thirty-day mean (+/-s.d.) urinary excretion of thiamine was 526.5+/-193.0 microg/day (24.7+/-8.10% of intake). There was a highly significant correlation between individuals' 30-day means of thiamine intake and their mean excretion level (r=0.720; P=0.006), where 1 mg of thiamine intake predicted 268.2 microg of thiamine in urine. The correlations between intake and excretion remained significant when measurement from a single 24-h urine collection was used (r=0.56). CONCLUSION: Twenty-four-hour urinary thiamine can be used as a concentration biomarker for thiamine intake in dietary validation studies.