The aim of the SODIAT-2 study is to evaluate the effectiveness of dietary intake assessment tools in a real-world setting. These tools include wearable cameras, spot urine samples, capillary blood samples, and a web-based food frequency questionnaire (FFQ). The main questions it aims to answer are:

Is the accuracy of dietary assessment improved in free-living environments when a combination of subjective and objective assessments tools are used?

Secondary research questions are:

Can wearable cameras accurately monitor the daily dietary intake of free-living individuals? Does a combination of capillary blood samples and spot urine samples provide a robust assessment of the nutrient status and habitual dietary exposure in a free-living setting? Can data-driven integration of multiple emerging technologies create a dietary assessment tool that is low burden, accurate and scalable in free-living populations? Can a condensed FFQ estimate diet quality as effectively as a detailed FFQ?

Participants will:

Use the dietary assessment tools (wearable camera, spot urine, capillary blood, and eNutri FFQ web-app) as instructed over a 5-week period from their home and/or working space.

Take part in two monitoring weeks (week 1 and week 5) where they will record their usual dietary intake over 3 days.

Consume an identical 3-day study meal plan during the test (calibration) diet week 3, whilst repeating the monitoring week measurements.

This study aims to recruit 133 adults living in Great Britain (GB) to better understand how these tools perform outside of a clinical environment.

The SODIAT project is a collaborative effort involving Aberystwyth University (AberU, project lead), University of Reading (UoR), Imperial College London (Imperial), and the University of Cambridge (UoC). Study 1, completed in July 2024, assessed the effectiveness of objective and subjective dietary intake assessment methods in highly-controlled clinical trial (protocol published at https://doi.org/10.12688/f1000research.155683.1) and informed the design of study 2.

Study 2 is led and sponsored by UoR. All study activities will be conducted remotely, with participants taking part from their usual locations (e.g., home, work).

►Screening and Welcome Week

Participants will use the online REDCap research platform to provide informed consent and complete a screening questionnaire to determine eligibility. Eligible participants will be contacted by a study researcher to discuss the study requirements, confirm consent, and schedule the study period.

A week before starting the 5-week study (Welcome Week), participants will be sent study materials/equipment and will be referred to the SODIAT webpage to view online video tutorials and read user guidelines for each study tool. Afterwards, participants will attend a video call with a study researcher to familiarize them with the study protocol and provide an opportunity to ask questions.

During the Welcome Week, participants will also self-collect a baseline blood sample (pre-video call) and complete the online eNutri FFQ to assess habitual diet. Within 2 days, they will then complete a condensed version of the FFQ to evaluate its effectiveness in estimating diet quality with reduced participant burden.

►5-week study period

Participants will follow their usual diet during weeks 1 & 5 and record their diet using study tools (wearable cameras, blood samples, urine samples and online FFQ) for 3 consecutive days (Monitoring Weeks). During week 3 (Calibration Week), participants will use the same study tools as before whilst consuming the 3-day test diet. There will be two test diets (one diet for meat/fish consumers and another slightly adapted for non-consumers), consisting of foods and drinks that are common in the UK. During this controlled part of the study, participants will be requested to eat/drink all foods and drinks provided (delivered by an online supermarket) but cannot consume anything extra. They will receive recommendations on serving sizes for each food/drink but participants can choose how much they eat (either more or less).

►Wearable cameras

Participants will wear a small camera unit mounted on glasses (or attached to their own frames) during the 3-day periods of weeks 1, 3, and 5 (days 1-3; 15-17 and 32-34). The camera automatically captures still images every 7 seconds to document food and drink intake. The camera will be worn from waking to going to bed, although participants will be instructed to remove the camera during private times (e.g., bathroom), sensitive locations (e.g., changing rooms, GP surgeries) and if unsafe to wear (e.g., driving), and log these occasions, as well as the camera start time, on a paper-based log. At the end of the study, encrypted SD cards containing the images will be returned to the research team at Imperial for secure processing.

Images will be pre-processed using AI to exclude irrelevant images, and blur identifying details (e.g., faces, device screens). Only anonymised images will be analysed by researchers to estimate dietary intake.

►Capillary blood samples

When fasted, participants will self-collect blood samples using OneDraw kits on day 4 of each study week (day 4, 18 and 35), which collect a few drops of blood from the upper arm/thigh onto a filter paper cartridge. A baseline sample will also be collected during the Welcome Week. Instructions and video tutorials will be provided, and samples will be mailed to researchers at UoC for storage and biomarker analysis.

►Spot urine samples

Over 4 consecutive days of each study week (days 1-4, 15-18, 32-35), participants will collect first morning void and last evening void urine samples using straw and vacuum tube kits. Samples will be temporarily stored in a refrigerator before mailing them to AberU for processing where biomarkers of food and drink intake will be analysed.

►Online FFQ (eNutri)

Participants will complete the online eNutri FFQ on six occasions. Both the original (long-format) and condensed FFQ will be completed during Welcome Week to capture habitual intake during the previous 4 weeks. During the study, a 3-day, condensed FFQ adapted to capture foods/drinks not well-represented by biomarker analysis, will be completed at the end of each recording week (day 4, 18 and 35). During the test diet week, the original FFQ, adapted to capture 3-day intakes, will also be completed (day 18). The FFQ inputs, nutrient and food group intakes, and diet quality data will be exported in pseudonymised format for analysis.

At the study's conclusion, participants will complete a short, online usability questionnaire about the study tools via REDCap (day 35).

Participants will mail their blood and urine samples at designated timepoints using pre-paid postage, and return all study equipment and logs at the end of the study via a courier collection.

Researchers will monitor adherence and communicate with participants as needed. Daily reminders will also be sent via email or text (SMS) message during the recording days.

► Statistical analysis

Accuracy of integrating multiple dietary assessment technologies to report dietary intake in free living environments will be measured during the calibration week (week 3) using dietary intake data collected from wearable cameras, spot urine samples, capillary blood samples, and self-reported FFQs.

Inclusion Criteria:

• 18 years and older
• Lives in Great Britain (England, Schotland and Walse)
• Able to read/understand instructions written in English and are fluent in English

Exclusion Criteria:

• Diagnosed or self-report as being underweight (have a body mass index (BMI) of less than 18.5 kg/m2)
• Are unwilling/unable to collect urine and blood samples, use the wearable camera as instructed and/or spend 20-30 min online recording what they've recently had to eat/drink on multiple occasions
• Are unwilling/unable to have a video call with a researcher with cameras turned on
• Are unwilling/unable to post samples on specific days and receive/send a larger parcel at the start/end of the study (note: all return packaging and postage will be provided by us and will include a courier delivery and collection)
• Are unwilling/unable to receive a single grocery delivery from Sainsbury's or Tesco online supermarkets (delivery to be arranged by us), includes living in a postcode area that cannot receive grocery deliveries from Tesco or Sainsburys as well as not having space to refrigerate and freeze items.
• Are unwilling/unable to eat/drink any items on the calibration menu, e.g., food allergies/intolerances, dislike of food items, unable eat (e.g. vegan or have to avoid for a medical condition) or cannot eat 3 meals plus snacks daily (note: vegetarians can take part)
• Are unwilling/unable to avoid taking dietary and herbal supplements for at least 1 week before and during the 5-week study (e.g. fish oils, vitamins, iron, protein shakes, nutrient powders, joint care)
• Are pregnant, may be pregnant or breast-feeding
• Currently experiencing, recovering or at a high risk of an eating disorder (e.g., previous diagnosis, or concerns that you have an unhealthy relationship with food)
• Have a health condition, are taking medication and/or undergoing medical treatment that affects metabolism, appetite and/or ability to eat the calibration menu (e.g. cancer, chemotherapy, diabetes, gastrointestinal disorders (such as inflammatory bowel disease, Crohn's disease), kidney disease, liver disease, HIV or AIDS)
• Are taking any of the following medications: androgens, blood thinners, phenytoin, erythromycin, or thyroid hormones
• Long-term use of any of the following medications: anti-inflammatories (NSAIDS), steroids/corticosteroids or antibiotics (eligible following a 4-week washout after short term use; eligible if use is infrequent)
• Use illicit substances/recreational drugs
• Have been diagnosed with dementia or other conditions affecting memory
• Do not have anyone at home, work, etc. to help them if they require assistance to use the study tools (such as arthritis, Parkinson's disease, sight loss, etc.)

If the participants have recently taken part in another intervention study, a 4-week washout will be required before they are able to start the study.

UK population.

Anonymised individual participant data will be shared in accordance with confidentiality and consent agreements. This may include: sociodemographic information, anthropometric measurements, dietary intake data, blood and urine biomarkers. Public data repositories (to be agreed by the project team) will be used preserving fully anonymised individual data.

To be made available at the point of publication.

The SODIAT Project Lead, Dr Manfred Beckmann (AberU) will have overall authority over the central data repository. The Principal Investigator at UoR, Professor Julie Lovegrove, will have authority over any data collected and stored at UoR, including REDCap and eNutri.