By: Selena Wu (BSc Nutrition and Dietetics and Registered dietitian), and Manca Rupel (ANutr, MSc Nutrition) from Kings College London.
Plant foods are packed with fibre and nutrients, and they are linked to lower risks of getting various diseases, particularly cardiovascular disease which impacts our heart and blood vessels – the network that transports our blood around the body (1). This isn’t breaking news; these are things we have known for years. Yet only 31.4% of adults in the UK meet the “5-a-day” recommendations (2). This has dropped from 34.9% in 2020 (2).
Importantly, plant foods feed our gut microbiota, which are the community of tiny living bugs such as bacteria, viruses, and fungi known as microbes. Even though bugs in general get a bad rap because some can cause disease (these are known as pathogens), most are actually beneficial to us (3). We need them to help keep us healthy. If we imagine the microbiota as a village, like in every community, there are always some bad apples. Beneficial bacteria take up the real estate that pathogens want, and they help stop them from moving in or starting families. The research suggests that it’s not just about how many microbes are in the system, but the types and diversity as well. We can’t have all bakers or all builders; we need different people to do different things. More does not always mean better; there needs to be a balance.
Everyone’s gut microbiome is different, and it houses trillions of microbes that help us digest food and get the most from the plants we eat (4). In return, they produce compounds called metabolites, many of which are thought to improve heart and metabolic (which involves converting food to building and storage blocks, and energy) health through potentially reducing inflammation, blood pressure, cholesterol, and regulating immune function.
Increasing the amount of plant foods we eat is certainly a good start, but emerging research suggests that the true power of these foods lies in their natural complexity. Rather than relying on isolated nutrients or a single “superfood,” health benefits are driven by how different natural compounds (like various fibres and plant-based compounds) interact within the body. In fact, studies show that individuals who maintain a rich, plant-based diet exhibit significantly better markers of heart and metabolic health, such as higher levels of “good” HDL cholesterol and better blood sugar control, though lifestyle and body weight also play a role (1). Interestingly, data indicate that simply increasing the quantity of a single food group doesn’t trigger the same protective metabolic shifts as a more comprehensive dietary approach (5). This highlights the need to better understand the deep connection between daily plant intake, our gut environment, and systemic cardiovascular health.
Although we know that eating more plant foods is generally associated with better health, scientists are still trying to understand why. Much of the research so far has looked at people’s usual eating habits and compared them with health outcomes over time (1). While these studies can identify important patterns, they cannot always tell us whether diet itself is responsible or whether other lifestyle factors, such as physical activity, sleep or body weight, are also playing a role (1). We also know surprisingly little about how different plant foods influence the gut microbiome and whether changes in the microbiome directly contribute to improvements in heart and metabolic health (1). Carefully controlled nutrition studies are therefore needed to help answer these questions and build the evidence that can inform future dietary recommendations.
Researchers at King’s College London are currently investigating these questions through the PLANTIFUL Study, which explores how plant food intake influences the gut microbiome and markers of gastrointestinal and cardiometabolic health in healthy adults. Participants are provided with most of their meals over a four-week period, allowing researchers to carefully study how changes in diet affect the body while reducing many of the day-to-day differences that make nutrition research so challenging. If you or someone you know is a healthy adult aged 30-70 years and would like to contribute to this exciting area of research, you can find more information about taking part in the PLANTIFUL Study here: https://www.kcl.ac.uk/research/the-plantiful-study-plant-foods-and-their-impact-on-gastrointestinal-and-cardiometabolic-health
https://clinicaltrials.gov/study/NCT07586111
References:
- Creedon, A., Foyle, L., Arulpragasam, M.G., McCall, N., Gibson, R. and Dimidi, E., 2025. Associations between plant-based food diversity and cardiometabolic outcomes in adults: A cross-sectional analysis of the UK National Diet and Nutrition Survey Year 9. Proceedings of the Nutrition Society, 84(OCE3), p.E213.
- Office for Health Improvement and Disparities (2026) Public Health profiles: Percentage of adults meeting the ‘5-a-day’ fruit and vegetable consumption recommendations (new method) 2020-2025.
- Aggarwal, N., Kitano, S., Puah, G.R.Y., Kittelmann, S., Hwang, I.Y. and Chang, M.W., 2022. Microbiome and human health: current understanding, engineering, and enabling technologies. Chemical Reviews, 123(1), pp.31-72.
- Hou, K., Wu, ZX., Chen, XY. et al. Microbiota in health and diseases. Sig Transduct Target Ther 7, 135 (2022). https://doi.org/10.1038/s41392-022-00974
- Bolo, A., Wang, J., Carpentier, F., Salomé, M., Verger, E.O., Fouillet, H. and Mariotti, F., 2025. Dietary diversity is differentially associated with diet quality across food groups. European Journal of Nutrition, 64(5), p.236.
Medical disclaimer
This content is for general information only and is not a substitute for professional medical advice. Always consult your GP or a qualified healthcare professional if you have any concerns about your health.