The purpose of this study is to evaluate the impact of replacing usual snacks with alternative snack foods on the immune response to influenza vaccination in a population of healthy, middle-aged adults.
Nutrition plays an important role in the immune system by providing energy and metabolites to support the function of immune cells, allowing them to initiate effective immune responses. Diet is therefore a modifiable factor in impacting immune function and is currently a topic of substantial interest in health research. Snack consumption has been shown to account for approximately 20-30% of daily energy intake in adults. Therefore, snack choices have the potential to influence dietary intake and quality, and therefore immune function, both positively and negatively. This study assesses the effect of replacing usual snacks with alternative snack foods on the immune response in a model of viral infection - the seasonal influenza vaccine containing four prevalent influenza virus strains for the 2022/23 or 2023/24 influenza season, as determined by the World Health Organization. This study is a parallel group, randomised controlled trial that will examine the replacement of usual snack foods with alternative snack foods on the immune response to seasonal influenza vaccination in humans, which will be assessed by measuring rates of seroconversion, and other immunological markers following vaccination. The intervention will be for 8 weeks, and influenza vaccination will be administered at 4-week midpoint. Participants will be followed up 3 months post-vaccination to assess incidence of upper respiratory symptoms.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
88
To be eaten in replacement of usual snacks twice a day for 8 weeks.
To be eaten in replacement of usual snacks twice a day for 8 weeks.
King's College London
London, United Kingdom
RECRUITINGRates of seroconversion for ≥1 influenza virus strain
The proportion of participants achieving seroconversion (≥4-fold increase in specific antibody titre) in at least one influenza virus strain. Titres will be assessed using the Hemagglutination Inhibition Assay (HAI) and fold change will be calculated.
Time frame: Week 8
Rates of seroconversion for A/Wisconsin/588/2019 (H1N1)pdm09-like virus strain (strain 1a)
The proportion of participants achieving seroconversion for A/Wisconsin/588/2019 (H1N1)pdm09-like virus strain. Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Rates of seroconversion for A/Wisconsin/67/2022 (H1N1)pdm09-like virus strain (strain 1b)
The proportion of participants achieving seroconversion for A A/Wisconsin/67/2022 (H1N1)pdm09-like virus strain. Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Rates of seroconversion for A/Darwin/6/2021 (H3N2)-like virus strain (strain 2)
The proportion of participants achieving seroconversion for A/Darwin/6/2021 (H3N2)-like virus strain. Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Rates of seroconversion for influenza virus B/Austria/1359417/2021 (B/Victoria lineage)-like virus strain (strain 3)
The proportion of participants achieving seroconversion for B/Austria/1359417/2021 (B/Victoria lineage)-like virus strain. Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Rates of seroconversion for B/Phuket/3073/2013 (B/Yamagata lineage)-like virus strain (strain 4)
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The proportion of participants achieving seroconversion for B/Phuket/3073/2013 (B/Yamagata lineage)-like virus strain. Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Proportion of participants who do not achieve seroconversion for any influenza virus strain
Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Rates of seroconversion for only 1 influenza virus strain
The proportion of participants achieving seroconversion for 1 influenza virus strain. Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Rates of seroconversion for 2 influenza virus strains
The proportion of participants achieving seroconversion for 2 influenza virus strains. Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Rates of seroconversion for 3 influenza virus strains
The proportion of participants achieving seroconversion for 3 influenza virus strains. Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Rates of seroconversion for 4 influenza virus strains
The proportion of participants achieving seroconversion for all 4 influenza virus strains. Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Geometric mean antigen-specific titres for or A/Wisconsin/588/2019 (H1N1)pdm09-like virus strain (strain 1a)
Titres will be assessed by HAI.
Time frame: Week 0, 4 and 8
Geometric mean antigen-specific titres for A/Wisconsin/67/2022 (H1N1)pdm09-like virus strain (strain 1b)
Titres will be assessed by HAI.
Time frame: Week 0, 4 and 8
Geometric mean antigen-specific titres for A/Darwin/6/2021 (H3N2)-like virus strain (strain 2)
Titres will be assessed by HAI.
Time frame: Week 0, 4 and 8
Geometric mean antigen-specific titres for B/Austria/1359417/2021 (B/Victoria lineage)-like virus strain (strain 3)
Titres will be assessed by HAI.
Time frame: Week 0, 4 and 8
Geometric mean antigen-specific titres for B/Phuket/3073/2013 (B/Yamagata lineage)-like virus strain (strain 4)
Titres will be assessed by HAI assay.
Time frame: Week 0, 4 and 8
Fold change in antigen-specific titres for A/Wisconsin/588/2019 (H1N1)pdm09-like virus strain (strain 1a)
Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Fold change in antigen-specific titres for A/Wisconsin/67/2022 (H1N1)pdm09-like virus strain (strain 1b)
Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Fold change in antigen-specific titres for A/Darwin/6/2021 (H3N2)-like virus strain (strain 2)
Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Fold change in antigen-specific titres for B/Austria/1359417/2021 (B/Victoria lineage)-like virus strain (strain 3)
Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Fold change in antigen-specific titres for B/Phuket/3073/2013 (B/Yamagata lineage)-like virus strain (strain 4)
Titres will be assessed by HAI and fold change will be calculated.
Time frame: Week 8
Seroprotection for ≥1 influenza virus strain
The proportion of participants achieving seroprotection (HAI titre of ≥1:40) in at least one of the four influenza virus strains.
Time frame: Week 8
Seroprotection for A/Wisconsin/588/2019 (H1N1)pdm09-like virus strain (strain 1a)
The proportion of participants achieving seroprotection (HAI titre of ≥1:40) for A/Wisconsin/588/2019 (H1N1)pdm09-like virus strain.
Time frame: Week 8
Seroprotection for A/Wisconsin/67/2022 (H1N1)pdm09-like virus strain (strain 1b)
The proportion of participants achieving seroprotection (HAI titre of ≥1:40) for A/Wisconsin/67/2022 (H1N1)pdm09-like virus strain.
Time frame: Week 8
Seroprotection for A/Darwin/6/2021 (H3N2)-like virus strain (strain 2)
The proportion of participants achieving seroprotection (HAI titre of ≥1:40) for A/Darwin/6/2021 (H3N2)-like virus strain.
Time frame: Week 8
Seroprotection for B/Austria/1359417/2021 (B/Victoria lineage)-like virus strain (strain 3)
The proportion of participants achieving seroprotection (HAI titre of ≥1:40) for B/Austria/1359417/2021 (B/Victoria lineage)-like virus strain.
Time frame: Week 8
Seroprotection for B/Phuket/3073/2013 (B/Yamagata lineage)-like virus strain (strain 4)
The proportion of participants achieving seroprotection (HAI titre of ≥1:40) for B/Phuket/3073/2013 (B/Yamagata lineage)-like virus strain.
Time frame: Week 8
Proportion of participants who do not achieve seroprotection for any influenza virus strains
Seroprotection is defined as HAI titre of ≥1:40
Time frame: Week 8
Seroprotection for 1 influenza virus strain
The proportion of participants achieving seroprotection (HAI titre of ≥1:40) for 1 influenza virus strain.
Time frame: Week 8
Seroprotection for 2 influenza virus strains
The proportion of participants achieving seroprotection (HAI titre of ≥1:40) for 2 influenza virus strains.
Time frame: Week 8
Seroprotection for 3 influenza virus strains
The proportion of participants achieving seroprotection (HAI titre of ≥1:40) for 3 influenza virus strains.
Time frame: Week 8
Seroprotection for 4 influenza virus strains
The proportion of participants achieving seroprotection (HAI titre of ≥1:40) for all 4 influenza virus strains.
Time frame: Week 8
Markers of immunological function
Isolation of peripheral blood mononuclear cells (PBMCs) to assess markers of immunological function.
Time frame: Week 0, 4 and 8
Incidence of upper respiratory symptoms
Measured using the Wisconsin Upper Respiratory Symptom Survey (WURSS-24).
Time frame: Week 4, 8, 12 and 16
Faecal gut microbiota (composition, alpha- and beta-diversity)
Measured by 16S community profiling (Illumina Miseq) of bacterial genomic DNA isolated from stool samples.
Time frame: Week 0, 4 and 8
Faecal short-chain fatty acids (SCFA)
Measured by gas liquid chromatography of stool samples.
Time frame: Week 0, 4 and 8
Faecal water
Determined from stool samples by oven-drying.
Time frame: Week 0, 4 and 8
Gut symptoms
Measured using the Gastrointestinal Symptom Rating Scale (GSRS) (7-day diary; questionnaire).
Time frame: Week 0, 4 and 8
Stool frequency
Measured using self-reported number bowel movements daily recorded in a 7-day diary.
Time frame: Week 0, 4 and 8
Stool consistency
Measured using the Bristol stool form scale (7-day dairy; questionnaire).
Time frame: Week 0, 4 and 8
Serum Vitamin E levels
Measured in blood sample - analysis of serum vitamin E levels by Liquid chromatography-mass spectrometry.
Time frame: Week 0, 4 and 8
Serum Zinc levels
Measured in blood sample - analysis of serum zinc levels by automated assay.
Time frame: Week 0, 4 and 8
Mental health status
Measured using The Patient Health Questionnaire Anxiety and Depression Scale (PHQ-ADS). Scores range from 0-48 with higher scores indicating more severe depression/anxiety.
Time frame: Week 0, 4 and 8
Dietary intake
7-day food and drink diary.
Time frame: Week 0, 4 and 8
Physical activity
Measured using the International Physical Activity Questionnaire (IPAQ).
Time frame: Week 0, 4 and 8
Acceptability of snack products
Measured using an Acceptability of dietary intervention questionnaire developed by King's College London for use in dietary intervention studies. The questionnaire assesses acceptability using a number of domains including flavour, texture, portion size.
Time frame: Week 8
Compliance
Return of unused snacks at the final visit (consumption of \>75% of total snacks will be considered compliant).
Time frame: Week 8
Adverse events
Interview-administered questionnaire.
Time frame: Week 0 - 8