Household introduction of new healthy and sustainable plant-based foods to assess diet incorporation and food acceptance among Portuguese and Swiss consumers
| ISRCTN | ISRCTN67949258 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN67949258 |
| HORIZON-CL6-2024-FARM2FORK-01 | 101180399 |
| Sponsor | Universidade do Porto |
| Funders | HORIZON EUROPE Framework Programme, Swiss State Secretariat for Education, Research and Innovation (SERI) |
- Submission date
- 24/03/2026
- Registration date
- 25/03/2026
- Last edited
- 25/03/2026
- Recruitment status
- No longer recruiting
- Overall study status
- Ongoing
- Condition category
- Other
Plain English summary of protocol
Background and study aims
Current food consumption is harming both human health and the environment. While unhealthy diets are a major cause of diseases such as obesity, heart disease and diabetes, food production places a heavy burden on the planet, using large amounts of natural resources. For this reason, international organisations such as the World Health Organization (WHO), the European Commission and the Intergovernmental Panel on Climate Change (IPCC), recommend a shift towards healthier and more sustainable diets, with a stronger focus on plant-based foods. These recommendations aim to improve population health while reducing environmental impact.
However, the intake of whole or minimally processed plant-based foods (such as whole grains, fruits, vegetables, and legumes) is frequently below recommended levels. As a result, important plant-based components such as dietary fibre are consumed in insufficient quantities compared to recommendations. Fibre is essential for good digestion and gut health, and it reduces the risk of major chronic conditions, such as heart disease, diabetes, obesity, and some types of cancer. Similarly, fermented foods are important contributors to a healthy gut microbiota and overall health, but are consumed unevenly across Europe, and are often not part of daily diets.
In the ‘Sustain-a-bite’ project, innovative and efficient processes are being developed to enable the production of new, minimally processed plant-based foods that are healthy, nutritious, and environmentally friendly. However, people may be unsure about new foods or unfamiliar production methods, which can jeopardise the success of these innovations.
The objective of this study is to understand how consumers accept and incorporate new healthy, sustainable plant-based foods, similar to those being developed in the ‘Sustain-a-bite’ project, into their daily diets. The study also aims to explore how repeatedly consuming plant-based, fibre-rich, fermented foods impacts consumers’ diet quality, nutritional status, and health perceptions.
Who can participate?
Couples residing in Portugal or Switzerland for at least 10 years can participate, regardless of their marital status. Participants must be healthy, non-pregnant adults (20-60 years of age), have no food allergies or intolerances related to the foods to test, eat meat and other animal-based foods, be familiar with kombucha and hummus, and be available to eat unknown plant-based foods and to collect all the study’s necessary information with quality.
What does the study involve?
A minimum of 80 participants (40 couples) is recruited in each country. Before enrolment, an anonymous questionnaire will be administered to all interested couples to determine eligibility to participate. A study information session will be held at each participating centre in each country. Once couples’ eligibility is verified and they provide informed consent, they are enrolled in the study and undergo the first moment of participants’ characterisation, which includes data on sociodemographic and dietary patterns, as well as information on the participants' beliefs, opinions and knowledge towards food and health.
Before the beginning of the intervention (week 0), participants will attend the first sensory lab evaluation, in which they will taste and evaluate four plant-based food products: Hummus (traditionally middle Eastern paste made from cooked chickpeas), Kombucha (fermented tea beverage originally from East Asia), Mämmi (traditional Finnish pudding-like food, based wholegrain rye flour and rye/barley malt) and Börs (traditional Romanian fermented beverage made from wheat bran). Then, they will be provided with two weekly portions of each product per person for 4 weeks. During this time, each participant must consume each product twice a week, being free to choose the day, time, meal, mode of consumption and amount consumed. In each moment of consumption, they must fill a questionnaire in which they evaluate the product consumed and give details on its consumption. Another three sensory lab sessions will be carried out in the middle (end of week 2), end (week 5), and one month after the end (week 9) of the intervention. Throughout the study period, additional information on the participants’ eating behaviour and food choices will be collected, and anthropometric data will be measured. Finally, individual interviews will be conducted in one member of each couple at the end (week 5) and one month after the end (week 9) of the intervention to assess their overall experience, including their opinions about the products, drivers and barriers to consumption.
What are the possible benefits and risks of participating?
All foods used in this intervention are commercially available in Europe. As such, they comply with European food safety regulations. The sensory lab evaluations of the intervention foods will be conducted by qualified staff and overseen by technical and scientific experts. At the beginning of the study, participants are fully informed about the food products' characteristics, namely ingredients, allergens, nutritional composition, shelf-life and adequate use and storage practices. They will also be provided with contact information of dedicated team members, who will be available for any further assistance throughout the study. As such, no risks or discomforts are expected for participants, other than the time and commitment required to participate in the study.
Couples will receive financial compensation for their participation. The findings from this study will be used to develop more efficient techniques for producing affordable, nutritious plant-based foods. This will, in turn, promote healthier, more sustainable diets among European adults.
Where is the study run from?
This study is run from the Faculty of Sciences of the University of Porto (Porto, Portugal) and Bern University of Applied Sciences (Bern, Switzerland).
When is the study starting, and how long is it expected to run for?
November 2025 to May 2026
Who is funding the study?
This project has received funding from the European Union’s Horizon Europe Research and Innovation programme under Grant Agreement No 101180399 (Project Sustain-a-bite), and by the Swiss State Secretariat for Education, Research and Innovation (SERI).
Who is the main contact?
Professor Luís Miguel Cunha, lmcunha@fc.up.pt
Professor Thomas Brunner, thomas.brunner@bfh.ch
Contact information
Principal investigator, Scientific
Geociências, Ambiente e Ordenamento do Território
FACULDADE DE CIÊNCIAS DA UNIVERSIDADE DO PORTO
Campus Agrário de Vairão, Edf. FCV2
Rua da Agrária, 747
Vila do Conde
4485-646
Portugal
 ORCID ID |
0000-0002-4590-7533 |
|---|---|
| Phone | +351-917772498 |
| lmcunha@fc.up.pt |
Public
FACULDADE DE CIÊNCIAS DA UNIVERSIDADE DO PORTO
Campus Agrário de Vairão, Edf. FCV2
Rua da Agrária, 747
Vila do Conde
4485-646
Portugal
| ORCID ID |
0000-0001-8389-1758 |
|---|---|
| Phone | +351-968823143 |
| sofia.sousa@fc.up.pt |
Study information
| Primary study design | Interventional |
|---|---|
| Allocation | N/A: single arm study |
| Masking | Open (masking not used) |
| Control | Uncontrolled |
| Assignment | Single |
| Purpose | Basic science, Prevention, Better understand how unfamiliar fibre-rich and fermented food products are adopted by consumers |
| Scientific title | A 4-week home-based intervention to assess diet incorporation and food acceptance of new minimally-processed, fibre-rich, and fermented plant-based foods among healthy adults from Portugal and Switzerland |
| Study acronym | Pro3F-Fit |
| Study objectives | Unhealthy dietary patterns are a leading contributor to non-communicable diseases, including obesity, cardiovascular disease, and type 2 diabetes, while current food systems place substantial pressure on environmental sustainability. International organisations, including the World Health Organization (WHO), the European Commission and the Intergovernmental Panel on Climate Change (IPCC), recommend a transition towards healthier and more sustainable dietary patterns, characterised by higher consumption of plant-based foods. However, the intake of whole and minimally processed plant-based foods (such as legumes, whole grains, fruits, and vegetables) remains below recommended levels across Europe, while meat and other animal-based products are commonly overconsumed. In the ‘Sustain-a-bite’ project, innovative processes are being developed to produce novel, minimally processed plant-based foods that are both nutritious and environmentally sustainable. However, consumer acceptance of such foods, particularly those produced using unfamiliar methods, remains uncertain and may represent a barrier to their adoption. The main objective of this intervention is to introduce new healthy, sustainable plant-based foods, similar to those being developed in the ‘Sustain-a-bite’ project, into the daily diets of healthy adults, to study how they accept and incorporate these food products, and to identify the main drivers and barriers of consumption. The study will also explore how repeated exposure to plant-based fibre-rich and fermented foods impacts consumers’ diet quality, nutritional status and health perceptions. |
| Ethics approval(s) |
Approved 23/01/2025, Ethical committee of the Faculty of Sciences, University of Porto (Rua do Campo Alegre , s/n, Porto, 4169-007, Portugal; +351 220402000; comissao.etica@fc.up.pt), ref: Proc. CE2024/p182 |
| Health condition(s) or problem(s) studied | Low consumption of minimally-processed, fibre-rich and fermented plant-based foods associated with unhealthy and unsustainable dietary patterns frequently observed in Western populations. |
| Intervention | A 10-week single-arm home-based intervention trial will be conducted in Portugal and Switzerland. A study information session will be held at each country’s participating centres for all interested couples who meet the eligibility criteria. In these sessions, researchers will explain the study objectives, methodology and data to be collected. An information brief containing the main product details from the respective labels, including the ingredients list, allergen information, nutrition declaration, and storage conditions, will also be provided. After signing the informed consent, participants are enrolled in the study. Over four weeks (intervention period, week 1 to week 4), participants will be repeatedly exposed to four plant-based food products, corresponding to two fibre-rich foods and two fermented beverages. Two are unfamiliar products from other European countries: (1) Mämmi, a traditional Finnish pudding-like food, based on wholegrain rye flour and rye/barley malt; and (2) Börs, a traditional Romanian fermented beverage made from wheat bran. The other two are products of similar typology that have already become popular across Europe: (1) Hummus, a traditionally Middle Eastern paste made from cooked chickpeas; and (2) Kombucha, a fermented tea beverage originally from East Asia. The latter will be used as a comparison point to identify the drivers of their success in the European market. Every week, participants will receive two portions of each of these food products. They will be asked to consume each product twice a week, with no restrictions on order, mode of consumption, or amount consumed, ranging from a minimal taste to a full portion. At each consumption moment, they will complete a questionnaire, providing data on overall liking, acceptance, emotional response, amount consumed and contextual details (including time, location, meal occasion, social and situational contexts). In addition, participants will upload photographic records documenting the mode and circumstances of consumption, including accompanying foods and/or beverages, if any. A total of four tasting sessions will be conducted at the sensory laboratory at baseline (week 0), mid-intervention (end of week 2), post-intervention (week 5), and one-month follow-up (week 9), to assess hedonic and emotional responses and identify main sensory descriptors. Furthermore, individual qualitative interviews with one member of each couple will be conducted at weeks 5 and 9, to explore participants’ overall experience, perceptions, drivers and barriers to consumption. Comprehensive characterisation of participants (e.g., sociodemographics, food neophobia, food choice criteria, nutrition knowledge) will be conducted using online questionnaires, to assess potential factors influencing diet incorporation and acceptance of these foods. To evaluate dietary and anthropometric changes, validated food frequency questionnaires will be completed at baseline (week 0) and one-month follow-up (week 9), and anthropometric measures will be collected immediately before (week 0) and after (week 5) the intervention. |
| Intervention type | Behavioural |
| Primary outcome measure(s) |
|
| Key secondary outcome measure(s) |
|
| Completion date | 15/05/2026 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Adult |
| Lower age limit | 20 Years |
| Upper age limit | 60 Years |
| Sex | All |
| Target sample size at registration | 160 |
| Total final enrolment | 180 |
| Key inclusion criteria | DEMOGRAPHICS 1. Age: 20-60 years 2. Household composition: couples (i.e., two adults in a conjugal relationship and living together) DIET 3. Dietary pattern: includes meat and other animal-based foods (i.e., omnivorous or flexitarian) 4. Familiarity: having consumed kombucha and hummus before ABILITIES, RESOURCES AND COMMITMENT 5. Independent users of each country’s official languages 6. Independent internet users 7. Owners of an electronic device compatible with the requirements for home-based data collection 8. Have sufficient time, skills and resources to adhere to the study protocol, namely to complete all self-assessments, to pick up all provisions as scheduled and to safely store the food products 9. Willingness to consume unfamiliar plant-based foods 10. No simultaneous participation in another trial during the study period 11. No planned absences from home (≥ 3 consecutive days) during the study period 12. Informed consent to participate |
| Key exclusion criteria | 1. Self-reported diagnosis of acute or chronic diseases requiring continuous medical treatment or dietary therapy 2. Food allergies or intolerances to the study food products and their ingredients 3. Pregnancy or intention to conceive during the study period 4. Residence in Portugal/Switzerland for less than 10 years 5. Failure to meet the predefined data quality criteria (e.g., incomplete or inconsistent responses, errors in data quality checks) |
| Date of first enrolment | 01/11/2025 |
| Date of final enrolment | 28/02/2026 |
Locations
Countries of recruitment
- Portugal
- Switzerland
Study participating centres
Vila do Conde
4169-007
Portugal
Zollikofen
CH-3052
Switzerland
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|---|
| IPD sharing plan summary | Not expected to be made available |
| IPD sharing plan |
Editorial Notes
25/03/2026: Trial's existence confirmed by Ethical committee of the Faculty of Sciences, University of Porto.
