NIST micronutrients measurement quality assurance program: characterizing individual participant measurement performance over time

Feasibility Outcomes of a Pilot Randomized Clinical Trial to Increase Cruciferous and Green Leafy Vegetable Intake in Posttreatment Head and Neck Cancer Survivors

BACKGROUND

Higher intakes of cruciferous vegetables (CVs) and green leafy vegetables (GLVs) in observational studies are associated with improvements in survival and cancer-related biomarkers in patients diagnosed with head and neck cancer (HNC). These results have yet to be corroborated in a randomized clinical trial (RCT).

OBJECTIVE

Determine the feasibility of implementing a 12-week RCT to increase CV and GLV intake in posttreatment HNC survivors.

DESIGN AND PARTICIPANTS

This was a two-arm RCT conducted among 24 posttreatment HNC survivors. Survivors were recruited from a southeastern, National Cancer Institute-designated Comprehensive Cancer Center between January 2015 and September 2016.

INTERVENTION

There were two groups: (1) an experimental group (n=12) receiving weekly 15- to 30-minute telephone dietary counseling from a registered dietitian nutritionist stressing 2.5 cups per week CVs and 3.5 cups per week GLVs, and (2) an attention control group (n=12) receiving weekly 15- to 30-minute telephone dietary counseling from a registered dietitian nutritionist focusing on general healthy eating for cancer survivors. Participants completed a baseline survey, three 24-hour dietary recalls, phlebotomy, and anthropometric measures prior to randomization and at the end of the 12-week study period. The experimental group also completed weekly vegetable record recalls.

MAIN OUTCOME MEASURES

Primary outcomes included feasibility, recruitment, retention, adherence, and safety. Secondary outcomes included inflammatory markers and carotenoids.

STATISTICAL ANALYSES PERFORMED

Descriptive statistics were generated for demographic, epidemiological, and clinical variables as well as the primary feasibility outcomes. Between- and within-group comparisons of mean serum cytokine and carotenoid levels were performed using appropriate statistical tests depending on their respective distributions for the purpose of generating preliminary effect sizes.

RESULTS

Overall, 350 incident HNC cases were screened for eligibility, and 98 were eligible for study participation. Reasons for ineligibility and exclusion included deceased (n=93); wrong or inactive telephone numbers, or unable to be reached, or lost to follow-up (n=93); not meeting inclusion criteria (n=39); and too ill to participate (n=27). Of the 98 eligible HNC cases, 24 agreed to participate, for an enrollment rate of 25%. The most common reason for nonparticipation was distance (n=48), as participants were asked to report for two on-site assignments. The retention rate was 96%. Mean intervention adherence rates for weekly goals were 67% CV, 74% GLV, and 71% overall. Completion rate of weekly counseling calls was 90%. The experimental group reported an overall mean increase of 5.5 cups GLV and 3.5 cups CV per week from baseline intake, respectively. No significant between- or within-arm differences were observed for inflammatory markers or carotenoids.

CONCLUSION

A posttreatment intervention aimed at increasing CV and GLV intake in HNC survivors is feasible. A larger RCT is needed to assess the efficacy of this intervention on disease outcomes.

Interlaboratory analytical comparison of fatty acid concentrations in serum or plasma

BACKGROUND

There are a large number of clinical studies focusing on the measurement of individual fatty acids in serum or plasma; however, few studies have focused on the interlaboratory comparisons of these measurements. The National Institutes of Standards and Technology (NIST), in collaboration with the National Institutes of Health Office of Dietary Supplements (NIH-ODS) and the Centers for Disease Control and Prevention (CDC), has initiated a quality assurance program for assessing and improving the comparability of individual fatty acid measurements in serum and plasma.

METHODS

This is a performance-based study so participants are encouraged to use their laboratory's methods for the quantification of the individual fatty acids that they typically measure in the unknown serum or plasma samples along with a control material. The control materials used to date are SRM 1950 Metabolites in Human Plasma and SRM 2378 Fatty Acids in Frozen Human Serum.

RESULTS

To date, two studies of the Fatty Acid Quality Assurance Program (FAQAP) have been completed with 11 and 14 participants, respectively. The agreement among the laboratories for individual fatty acids was within 20% for 70% of the data submitted. Laboratories were also requested to run triplicate analyses for each unknown sample. The precision of the individual laboratory data was generally good, with relative standard deviations <20%.

CONCLUSIONS

The results from the first two exercises indicate the need for additional assessment of the comparability among laboratories doing these measurements. Future studies will be conducted with the goals of increasing the number of participating laboratories, increasing awareness of the need to use control materials, and improving the comparability among laboratories.

The development and implementation of quality assurance programs to support nutritional measurements

The National Institute of Standards and Technology administers quality assurance programs devoted to improving measurements of nutrients and related metabolites in foods, dietary supplements, and serum and plasma samples. These programs have been developed in collaboration with the National Institutes of Health to assist measurement communities in their efforts to achieve accurate results that are comparable among different laboratories and over time. Targeted analytes include micronutrients, botanical markers, nutritional elements, contaminants, fatty acids, and vitamin D metabolites.

Diet adherence dynamics and physiological responses to a tomato product whole-food intervention in African-American men

Tomatoes may have beneficial effects on prostate health. Efficacy trials would require long-term adherence to high levels of tomato product (TP) consumption. Therefore, factors that affect adherence in men most at risk and whether increased consumption of TP negatively affects diet and health are important concerns. Cancer-free African–American (AA) men (n 36) with mean serum prostate-specific antigen of 7.4 SD 5.6) ng/ml were randomised to consume one serving of TP/d or a control diet for 3 months. Mean intervention group lycopene intake rose to 464%, with negligible control group increase. Plasma lycopene levels rose by 53 and 40% in the intervention group in months 1 and 3, respectively (P < 0.0001), with no control group change. The intervention group’s barriers to adherence score was inversely associated with both dietary (r -0.49, P = 0.02) and plasma lycopene concentration (r -0.37, P = 0.02). Their TP disadvantage score negatively correlated with the 3-month plasma lycopene concentrations (r -0.37, P = 0.008) and their weekly incentives and impediments were remarkably stable, ‘concern for prostate health’ being the most consistent over time. ‘Liking tomatoes’ and ‘study participation’ decreased in citation frequency at weeks 6 and 9, respectively. No major shifts occurred in dietary cholesterol or saturated fat, with no adverse effects on gastrointestinal complaints, serum total cholesterol, body weight or blood pressure. Lower socio-economic status AA men at higher prostate cancer risk can successfully achieve a whole food intervention goal with a corresponding rise in plasma lycopene concentrations, with no adverse effects on self-selected diet quality or health parameters.

Certification of vitamins and carotenoids in SRM 3280 multivitamin/multielement tablets

A new multivitamin/multielement dietary supplement Standard Reference Material (SRM) has been issued by the National Institute of Standards and Technology (NIST), with certified and reference concentration values for 13 vitamins, 24 elements, and 2 carotenoids. The constituents have been measured by multiple analytical methods with data contributed by NIST and by collaborating laboratories. This effort included the first use of isotope dilution mass spectrometry for value assignment of both fat-soluble vitamins (FSVs) and water-soluble vitamins (WSVs). Excellent agreement was obtained among the methods, with relative expanded uncertainties for the certified concentration values typically ranging from <2% to 15% for vitamins.

The CDC VITAL-EQA program, external quality assurance for serum retinol, 2003-2006

BACKGROUND

With approximately 127 million preschool children currently suffering from vitamin A deficiency globally, it is important for affected countries to have the capacity to determine the prevalence of vitamin A deficiency and to monitor the progress being made to eradicate this problem through supplementation and fortification programs. The VITamin A Laboratory-External Quality Assurance program (VITAL-EQA) administered by the US Centers for Disease Control and Prevention was developed in 2003 to help predominantly less developed countries to assess and improve their ability to accurately and precisely measure serum retinol, and more recently other nutritional indicators.

METHODS

Twice each year, laboratories test serum samples in duplicate over the course of 3 days. Results are returned and troubleshooting is performed if needed.

RESULTS

Measurement accuracy improved for 2 laboratories and declined for 2 laboratories, whereas the remainder of laboratories participating in >1 round showed consistently acceptable performance. Precision improved for 7 laboratories, declined for 4 laboratories, and remained at <or=5% coefficient of variation for the rest of the participants.

CONCLUSIONS

This program is a valuable tool for the assessment and improvement of retinol testing in laboratories throughout the world.

Accuracy and precision of two short screeners to assess change in fruit and vegetable consumption among diverse populations participating in health promotion intervention trials

Two short frequency questionnaires, the NCI 19-item Fruit and Vegetable Screener (FVS) and a single question on overall fruit and vegetable consumption (1-item), were evaluated for their ability to assess change in fruit and vegetable (FV) consumption over time and in response to intervention among participants in 5 health promotion trials in the Behavior Change Consortium. Cross-sectional differences and correlations of FV estimates at baseline and at follow-up were compared for the FVS (n = 315) and the 1-item (n = 227), relative to multiple 24-h recall interviews (24HR). The FVS significantly overestimated daily intake by 1.27 servings at baseline among men and by 1.42 and 1.59 servings at baseline and follow-up, respectively, in women, whereas the 1-item measure significantly underestimated intake at both time points in men (0.98 serving at baseline, 0.75 serving at follow-up) and women (0.61 and 0.41 serving). Cross-sectional deattenuated correlations with 24HR at follow-up were 0.48 (FVS) and 0.50 (1-item). To evaluate the capacity of the 2 screeners to assess FV change, we compared mean posttest effects with 24HR by treatment group overall and by gender. Treatment group differences were not significant for either 24HR or 1-item. Among 315 subjects, the FVS treatment group differences were significant both overall and within gender but not when repeated in the sample of 227. Findings suggest multiple 24HR at multiple time points in adequate sample sizes remain the gold standard for FV reports. Biases in FVS estimates may reflect participants' lifestyles and sociodemographic characteristics and require further examination in longitudinal samples representative of diverse populations.

Baseline design elements and sample characteristics for seven sites participating in the Nutrition Working Group of the Behavior Change Consortium

The purpose of this article is to describe the baseline design elements and sample characteristics of the Behavior Change Consortium (BCC) Dietary Measurement studies for each of the 7 sites that comprised the BCC Nutrition Working Group (NWG). This article summarizes the project designs, including descriptions of diverse study populations, primary assessment methods, and study outcomes. Common measures used across sites included the National Cancer Institute (NCI) Fruit and Vegetable Screener, NCI Percentage Energy from Fat Screener, 24-h dietary recalls, and a single- or 2-item fruit and vegetable measure. Data on sociodemographic characteristics, body weight and height, smoking status, and serum carotenoids were also collected. Study design information such as assessment time points, as well as baseline sample characteristics, is also described. This paper provides the overall framework and descriptive information and serves as the reference for the BCC NWG special supplement.

Correspondence of the NCI Fruit and Vegetable Screener to repeat 24-H recalls and serum carotenoids in behavioral intervention trials

Five sites participating in the NCI Behavior Change Consortium administered the NCI Fruit and Vegetable Screener (FVS) and multiple, nonconsecutive 24-h dietary recall interviews (24HR) to 590 participants. Three sites also obtained serum carotenoids (n = 295). Participants were primarily female, ethnically diverse, and varied by age and education. Correlations between 24HR and FVS by site ranged from 0.31 (P = 0.07) to 0.47 (P < 0.01) in men and from 0.43 to 0.63 (P < 0.01) in women. Compared with 24HR, FVS significantly (P < 0.05) overestimated intake at 2 of 4 sites for men and all 4 sites for women. Differences in estimated total servings of fruits and vegetables/d ranged from 0.16 to 3.06 servings. On average, the FVS overestimated intake by 1.76 servings in men and 2.11 servings in women. Alternative FVS scoring procedures and a 1-item screener lowered correlations with 24HR as well as serum carotenoids but alternate scoring procedures generally improved estimations of servings.

Uncertainty in aflatoxin B1 analysis using information from proficiency tests

We describe how to calculate uncertainty in the determination of aflatoxin B(1) in nuts and maize using an HPLC method with prederivatisation with trifluoroacetic acid and fluorescence detection. The uncertainty is easily calculated using the information obtained from the participation in several proficiency tests. All the sources of uncertainty are grouped in two terms: (1) matrix variability, intermediate precision and sample heterogeneity, and (2) method concordance. This methodology has the advantage that no extra work needs to be done because all the information to calculate uncertainty comes from proficiency tests. The uncertainty values were calculated using samples whose concentration ranged between 2 and 20 microg L(-1). The relative standard uncertainty computed for aflatoxin B(1) was 16.3%.

Effects of lycopene and tomato paste extracts on DNA and lipid oxidation in LNCaP human prostate cancer cells

Animal and epidemiological studies point to a cancer preventive/therapeutic role for tomato products and its antioxidant, lycopene. It is hypothesized that lycopene will behave as an antioxidant at low concentrations and as a prooxidant at high concentrations in LNCaP human prostate cancer cell culture systems. We characterized the antioxidant, and prooxidant effects of a hexane extract of tomato paste (TP) and water solubilized lycopene at different concentrations using a prostate cancer cell line. Placebo (5% triglyceride, Roche Inc.) was used as a control. After 6, 24 hr and 48 hr incubation, LNCaP cells were harvested and used for each measurement. Cellular proliferation was determined using the MTT colorimetric assay. Lycopene and TP hexane extract inhibited cell growth in a dose-dependent (0.1-50 microM lycopene) manner and growth inhibition was 55% and 35% at 1 microM lycopene and TP hexane extract, respectively after 48 hr incubation. The levels of 8-hydroxydeoxyguanosine/deoxyguanosine (an oxidative DNA damage product) was significantly increased starting at 5 microM lycopene from both TP hexane extract and pure lycopene after 24 and 48 hr incubation with no protection at the lower concentrations. Malondialdehyde formation (a lipid peroxidation product measured by HPLC separation of the MDA-TBA adduct) was significantly reduced at low concentrations (0.1-1 microM) of lycopene in all treatments. Clinically relevant concentrations of lycopene and the tomato fraction containing lycopene significantly reduced LNCaP cancer cell survival which can only be partially explained by increased DNA damage at high lycopene concentrations (> 5 microM). Low concentrations of lycopene acted as a lipid antioxidant but did not protect DNA.

Effects of tomato paste extracts on cell proliferation, cell-cycle arrest and apoptosis in LNCaP human prostate cancer cells

Since tomato consumption is associated with decreased risk of prostate cancer, cell proliferation, cell cycle progression and apoptosis by LNCaP human prostate cancer cells might elucidate action of tomatoes. To discover possible bioactive fractions of tomatoes, whole tomato paste and its water and hexane extract were used and biomarkers of carcinogenesis were measured. After 6, 24 and 48 hr of incubation, cells were harvested and determined cell growth. Tomato paste hexane extract inhibited cell proliferation by 33% compared to the control after 48 hr incubation. Whole tomato paste and its water extract showed only modest growth inhibition. Tomato paste hexane extract at 5 microM lycopene increased G2/M-phase of the cell cycle from 13 to 28% and decreased S-phase cells from 45 to 29%. Apoptosis was observed at the 5 microM hexane extract at the late stages during 24 and 48 hr treatment. Tomato, therefore, deserves study as a potential chemopreventive/chemotherapeutic agent.

A physiological pharmacokinetic model describing the disposition of lycopene in healthy men

A physiological pharmacokinetic model was developed to describe the disposition of lycopene, delivered as a tomato beverage formulation in five graded doses (10, 30, 60, 90, or 120 mg), for a phase I study in healthy male subjects (five per dose). Blood was collected before dose administration (0 h) and at scheduled intervals until 672 h. Serum concentrations of carotenoids and vitamins were measured by high performance liquid chromatography analysis. The model was comprised of seven compartments: gastrointestinal tract, enterocytes, chylomicrons, plasma lipoproteins, fast-turnover liver, slow-turnover tissues, and a delay compartment before the enterocytes. As predicted, the percent absorption at the 10 mg dose (33.9 +/- 8.1%) was significantly greater than at the higher doses; however, the amount of lycopene absorbed (mg) was not statistically different (mean: 4.69 +/- 0.55 mg) between doses, suggesting a possible saturation of absorptive mechanisms. The slow-turnover tissue compartment served as a slow-depleting reservoir for lycopene, and the liver represented the fast-turnover pool. Independent of dose, 80% of the subjects absorbed less than 6 mg of lycopene. This may have important implications for planning clinical trials with pharmacological doses of lycopene in cancer control and prevention if absorption saturation occurs at levels that are already being consumed in the population.

Pharmacokinetics and tissue distribution of orally administered lycopene in male dogs

Consumption of lycopene, the predominant carotenoid in tomatoes and tomato products, is associated with reduced prostate cancer risk. The purpose of this study was to measure the pharmacokinetics and tissue distribution of lycopene after oral administration to male dogs. After single doses of 10, 30 and 50 mg/kg body weight (BW) lycopene to 2 dogs/dose, the mean half-life was 36 h and the plasma systemic exposure levels (AUC(0-)( infinity ), area under the curve) after the 30 and 50 mg/kg BW doses were similar. In a repeat dose study, 30 mg/(kg BW. d) administered orally to six dogs for 28 d resulted in steady-state plasma concentrations between 785 and 997 nmol/L lycopene. Apparent clearance, volume of distribution and apparent elimination half-life were 2.29 L/(h. kg), 96 L/kg and 30.5 h, respectively. Dogs were killed 1 or 5 d after the last dose and 23 tissues were collected for lycopene analysis. Lycopene concentrations were highest in liver, adrenals, spleen, lymph nodes and intestinal tissues. Liver lycopene concentrations were 66 and 91 nmol/g 1 and 5 d after cessation of treatment, respectively. Prostate lycopene concentrations were < 0.2 nmol/g both 1 and 5 d after dosing ceased (<0.4% of liver concentrations). Although 70% trans-lycopene was used in the dosing material, most of the lycopene identified in plasma and tissues was cis-lycopene.

Esterification does not impair lutein bioavailability in humans

Age-related macular degeneration (ARMD) is inversely associated with the accumulation of lutein + zeaxanthin in the macula, but higher lutein intakes are inconsistently related to reduced risk of ARMD in epidemiologic studies. Resolution of efficacy awaits clinical trials designed with knowledge of lutein supplement pharmacokinetics. Lutein bioavailability was determined for lutein diester and unesterified lutein formulations as they might be incorporated into dietary supplements. Healthy subjects (n = 18) consumed a single dose of each formulation (either 0.5 or 0.67 micro mol lutein/kg body, 10 and 8 subjects, respectively) in random order, and the appearance of free lutein + zeaxanthin was measured in serum from 0 to 408 h. Areas under the serum concentration x time curves (AUC), as a measure of bioavailability, were independent of gender, body mass index and lutein dose. The lutein diester formulation was 61.6% more bioavailable than the unesterified lutein formulation with higher mean AUC, maximum serum concentration and ascending slope (P < 0.05). The AUC was greater in 14 of 18 subjects when they consumed the lutein diester formulation. Comparison with data from previous studies suggested that dissolution was a greater limitation to bioavailability than lutein ester hydrolysis because an oil-solubilized unesterified lutein preparation, given at 0.5 micro mol/kg body, resulted in greater mean peak concentrations and AUC compared with either the unesterified or lutein diester formulations used in our study. In conclusion, the lutein diester formulation poses no impediment to lutein bioavailability at the doses tested, but formulation dissolution is an important factor in lutein bioavailability and should be evaluated before a supplement and dose are selected for use in clinical trials.

Oxidative DNA damage in prostate cancer patients consuming tomato sauce-based entrees as a whole-food intervention

BACKGROUND

Human prostate tissues are vulnerable to oxidative DNA damage. The risk of prostate cancer is lower in men reporting higher consumption of tomato products, which contain high levels of the antioxidant lycopene. We examined the effects of consumption of tomato sauce-based pasta dishes on lycopene uptake, oxidative DNA damage, and prostate-specific antigen (PSA) levels in patients already diagnosed with prostate cancer.

METHODS

Thirty-two patients with localized prostate adenocarcinoma consumed tomato sauce-based pasta dishes for the 3 weeks (30 mg of lycopene per day) preceding their scheduled radical prostatectomy. Serum and prostate lycopene concentrations, serum PSA levels, and leukocyte DNA oxidative damage (ratio of 8-hydroxy-2'-deoxyguanosine [8-OHdG] to 2'-deoxyguanosine [dG]) were assessed before and after the dietary intervention. DNA oxidative damage was assessed in resected prostate tissue from study participants and from seven randomly selected prostate cancer patients. All statistical tests were two-sided.

RESULTS

After the dietary intervention, serum and prostate lycopene concentrations were statistically significantly increased, from 638 nM (95% confidence interval [CI] = 512 to 764 nM) to 1258 nM (95% CI = 1061 to 1455 nM) (P<.001) and from 0.28 nmol/g (95% CI = 0.18 to 0.37 nmol/g) to 0.82 nmol/g (95% CI = 0.57 to 1.11 nmol/g) (P <.001), respectively. Compared with preintervention levels, leukocyte oxidative DNA damage was statistically significantly reduced after the intervention, from 0.61 8-OHdG/10(5) dG (95% CI = 0.45 to 0.77 8-OHdG/10(5) dG) to 0.48 8-OHdG/ 10(5) dG (95% CI = 0.41 to 0.56 8-OHdG/10(5) dG) (P =.005). Furthermore, prostate tissue oxidative DNA damage was also statistically significantly lower in men who had the intervention (0.76 8-OHdG/10(5) dG [95% CI = 0.55 to 0.96 8-OHdG/10(5) dG]) than in the randomly selected patients (1.06 8-OHdG/10(5) dG [95% CI = 0.62 to 1.51 8-OHdG/10(5) dG]; P =.03). Serum PSA levels decreased after the intervention, from 10.9 ng/mL (95% CI = 8.7 to 13.2 ng/mL) to 8.7 ng/mL (95% CI = 6.8 to 10.6 ng/mL) (P<.001).

CONCLUSION

These data indicate a possible role for a tomato sauce constituent, possibly lycopene, in the treatment of prostate cancer and warrant further testing with a larger sample of patients, including a control group.