Validation of the Oxford WebQ Online 24-Hour Dietary Questionnaire Using Biomarkers.

The Oxford WebQ is an online 24-hour dietary questionnaire that is appropriate for repeated administration in large-scale prospective studies, including the UK Biobank study and the Million Women Study. We compared the performance of the Oxford WebQ and a traditional interviewer-administered multiple-pass 24-hour dietary recall against biomarkers for protein, potassium, and total sugar intake and total energy expenditure estimated by accelerometry. We recruited 160 participants in London, United Kingdom, between 2014 and 2016 and measured their biomarker levels at 3 nonconsecutive time points. The measurement error model simultaneously compared all 3 methods. Attenuation factors for protein, potassium, total sugar, and total energy intakes estimated as the mean of 2 applications of the Oxford WebQ were 0.37, 0.42, 0.45, and 0.31, respectively, with performance improving incrementally for the mean of more measures. Correlation between the mean value from 2 Oxford WebQs and estimated true intakes, reflecting attenuation when intake is categorized or ranked, was 0.47, 0.39, 0.40, and 0.38, respectively, also improving with repeated administration. These correlations were similar to those of the more administratively burdensome interviewer-based recall. Using objective biomarkers as the standard, the Oxford WebQ performs well across key nutrients in comparison with more administratively burdensome interviewer-based 24-hour recalls. Attenuation improves when the average value is taken over repeated administrations, reducing measurement error bias in assessment of diet-disease associations.

Validity of an online 24-h recall tool (myfood24) for dietary assessment in population studies: comparison with biomarkers and standard interviews.

BACKGROUND: Online dietary assessment tools can reduce administrative costs and facilitate repeated dietary assessment during follow-up in large-scale studies. However, information on bias due to measurement error of such tools is limited. We developed an online 24-h recall (myfood24) and compared its performance with a traditional interviewer-administered multiple-pass 24-h recall, assessing both against biomarkers. METHODS: Metabolically stable adults were recruited and completed the new online dietary recall, an interviewer-based multiple pass recall and a suite of reference measures. Longer-term dietary intake was estimated from up to 3 × 24-h recalls taken 2 weeks apart. Estimated intakes of protein, potassium and sodium were compared with urinary biomarker concentrations. Estimated total sugar intake was compared with a predictive biomarker and estimated energy intake compared with energy expenditure measured by accelerometry and calorimetry. Nutrient intakes were also compared to those derived from an interviewer-administered multiple-pass 24-h recall. RESULTS: Biomarker samples were received from 212 participants on at least one occasion. Both self-reported dietary assessment tools led to attenuation compared to biomarkers. The online tools resulted in attenuation factors of around 0.2-0.3 and partial correlation coefficients, reflecting ranking intakes, of approximately 0.3-0.4. This was broadly similar to the more administratively burdensome interviewer-based tool. Other nutrient estimates derived from myfood24 were around 10-20% lower than those from the interviewer-based tool, with wide limits of agreement. Intraclass correlation coefficients were approximately 0.4-0.5, indicating consistent moderate agreement. CONCLUSIONS: Our findings show that, whilst results from both measures of self-reported diet are attenuated compared to biomarker measures, the myfood24 online 24-h recall is comparable to the more time-consuming and costly interviewer-based 24-h recall across a range of measures.

Mycoprotein reduces energy intake and postprandial insulin release without altering glucagon-like peptide-1 and peptide tyrosine-tyrosine concentrations in healthy overweight and obese adults: a randomised-controlled trial.

Dietary mycoprotein decreases energy intake in lean individuals. The effects in overweight individuals are unclear, and the mechanisms remain to be elucidated. This study aimed to investigate the effect of mycoprotein on energy intake, appetite regulation, and the metabolic phenotype in overweight and obese volunteers. In two randomised-controlled trials, fifty-five volunteers (age: 31 (95 % CI 27, 35) years), BMI: 28·0 (95 % CI 27·3, 28·7) kg/m2) consumed a test meal containing low (44 g), medium (88 g) or high (132 g) mycoprotein or isoenergetic chicken meals. Visual analogue scales and blood samples were collected to measure appetite, glucose, insulin, peptide tyrosine-tyrosine (PYY) and glucagon-like peptide-1 (GLP-1). Ad libitum energy intake was assessed after 3 h in part A (n 36). Gastric emptying by the paracetamol method, resting energy expenditure and substrate oxidation were recorded in part B (n 14). Metabonomics was used to compare plasma and urine samples in response to the test meals. Mycoprotein reduced energy intake by 10 % (280 kJ (67 kcal)) compared with chicken at the high content (P=0·009). All mycoprotein meals reduced insulin concentrations compared with chicken (incremental AUClow (IAUClow): -8 %, IAUCmedium: -12 %, IAUChigh: -21 %, P=0·004). There was no significant difference in glucose, PYY, GLP-1, gastric emptying rate and energy expenditure. Following chicken intake, paracetamol-glucuronide was positively associated with fullness. After mycoprotein, creatinine and the deamination product of isoleucine, α-keto-ß-methyl-N-valerate, were inversely related to fullness, whereas the ketone body, ß-hydroxybutyrate, was positively associated. In conclusion, mycoprotein reduces energy intake and insulin release in overweight volunteers. The mechanism does not involve changes in PYY and GLP-1. The metabonomics analysis may bring new understanding to the appetite regulatory properties of food.

Selective ablation of peptide YY cells in adult mice reveals their role in beta cell survival.

BACKGROUND AND AIMS: In the pancreas, peptide YY (PYY) is expressed by a subpopulation of nonbeta cells in the islets of Langerhans. We investigated the function of these cells in the pancreas of adult mice. METHODS: We generated mice in which administration of diphtheria toxin (DT) led to specific ablation of PYY-expressing cells. We investigated the effects of loss of PYY cells on glucose homeostasis. RESULTS: Loss of PYY cells in adult mice resulted in severe hyperglycemia, which was associated with significant loss of pancreatic insulin and disruption of islet morphology. In vitro administration of DT to isolated islets significantly reduced numbers of PYY-expressing cells and levels of insulin. Administration of either pancreatic polypeptide (a strong agonist of the receptor Y(4)) or PYY(3-36) (a selective agonist of the receptor Y(2)) did not restore loss of pancreatic insulin following administration of DT. However, a long-acting PYY analogue reduced the loss of insulin, and administration of this analogue reduced the hyperglycemia and insulin loss induced by streptozotocin in mice. CONCLUSIONS: PYY appears to regulate beta cell function and survival via the receptor Y(1/2). These findings might be developed to treat and prevent loss of beta cells in patients with diabetes mellitus.

Free fatty acid receptor 2 and nutrient sensing: a proposed role for fibre, fermentable carbohydrates and short-chain fatty acids in appetite regulation.

The way in which the composition of the diet may affect appetite, food intake and body weight is now receiving considerable attention in a bid to halt the global year-on-year rise in obesity prevalence. Epidemiological evidence suggests that populations who follow a fibre-rich, traditional diet are likely to have a lower body weight and improved metabolic parameters than their Western-diet counterparts. The colonic effects of fibre, and more specifically the SCFA that the fermentation process produces, may play a role in maintaining energy homeostasis via their action on the G-coupled protein receptor free fatty acid receptor 2 (FFA2; formerly GPR43). In the present review, we summarise the evidence for and against the role of FFA2 in energy homeostasis circuits and the possible ways that these could be exploited therapeutically. We also propose that the decline in fibre content of the diet since the Industrial Revolution, particularly fermentable fractions, may have resulted in the FFA2-mediated circuits being under-utilised and hence play a role in the current obesity epidemic.

Sustained appetite improvement in malnourished dialysis patients by daily ghrelin treatment.

Malnutrition is a common complication in patients on dialysis and is strongly associated with poor prognosis. Effective therapy could substantially improve morbidity and mortality, but neither enteral nor parenteral supplementation provide long-term benefit because of the strong appetite suppression seen in such patients. We performed a double-blinded randomized crossover study of a week-long treatment with daily subcutaneous ghrelin, a gut hormone that regulates hunger through the hypothalamus, in a group of 12 malnourished dialysis patients. Ghrelin administration increased ghrelin levels in circulation, modestly reduced blood pressure for up to 2 h, and immediately and significantly increased appetite, with an increase in energy intake noted at the first study meal. Persistence of this effect throughout the week was confirmed with food diaries and final study meals. Energy expenditure, measured with free-living pulse and motion monitors, was unchanged by ghrelin. Our study shows that daily treatment with ghrelin achieves a sustained positive change in energy balance in malnourished dialysis patients. Direct manipulation of appetite with ghrelin or its analogs represents an attractive and promising therapeutic strategy for this difficult clinical problem.