People in the UK eat a median of eight different plants a day - including spices and fat-based oils - with some eating just two daily.
The study by researchers from the Department of Nutrition found that eating a more diverse range of plant-based foods is associated with better cardiometabolic health outcomes, including improved cholesterol levels, blood sugar markers, better overall diet quality and higher intakes of key nutrients, including fibre, vitamins, and minerals.
While the role of diet in preventing and managing conditions like cardiovascular disease and type 2 diabetes is well established, this study is the first of its kind to examine how many and which types of plant foods people in the UK consume, and how this diversity relates to cardiometabolic health markers which are important indicators of cardiovascular diabetes and type 2 diabetes.
Current dietary guidance in the UK often emphasises quantity, such as '5-a-day' for fruit and vegetables. Our findings suggest that dietary variety, across all plant-based food groups, may be just as important for improving diet quality and lowering the risk of cardiometabolic diseases.
Dr Eirini Dimidi, Senior Lecturer in Nutritional Sciences at King's College London and senior author of the study
The research, published in Clinical Nutrition, analysed data on over 670 adults from the UK National Diet and Nutrition Survey (NDNS) from 2016-2017. 97% of adults included followed an omnivorous diet.
Researchers grouped participants into three categories based on the variety of plant-based foods they consumed each day. Those in the low diversity group ate around 5.5 different plant foods per day, the moderate diversity group 8.1 types, and those in the high diversity group included roughly 11 different plant foods in their daily diets.
Blood tests showed that people with less plant diversity in their diets had lower HDL cholesterol, known as the "good" cholesterol. A lower level of this cholesterol generally indicates a lower risk of heart disease. They also found that HBA1C concentration - blood glucose levels - is lower for every one-unit increase in plant diversity.
The research also found that people with higher plant food diversity tended to have healthier lifestyle profiles. For example, only 6% of people in the high-diversity group smoked, compared with 30% in the low-diversity group. Those in the high-diversity group also had better blood lipid profiles and more met fibre recommendations compared to low and moderate groups. They had also consumed more total sugar, likely due to greater intake of fruits and fruit juices. While excess sugar can have negative health effects, fruits provide additional beneficial nutrients such as fibre and antioxidants, which may help offset these impacts on blood sugar and overall health.
Dr Dimidi said: "Vegetables were the largest contributors (21%) to diversity, followed by plant-based fats and oils (18.8%), and fruit (17%). Categories such as nuts, seeds, legumes, despite their established nutritional benefits, contributed minimally to total intake. While higher diversity was associated with better nutrient adequacy overall, key shortfalls remained even among those with the most diverse plant-based diets, particularly for fibre and several micronutrients which are important for maintaining a strong immune system and health bones and tissues."
In addition to fruits and vegetables, legumes, nuts, seeds, herbs and spices are great plant-based food sources that can help us to introduce more plant diversity into our diets.
Dr Dimidi
She added: "Try adding nuts to your porridge, spices to your baked beans. Branch out from the usual peas, onions or carrots with dinner, and try incorporating seasonal vegetables into your dinners - like courgettes, broccoli and broad beans in July."
Promoting a more diverse intake of plant-based foods-particularly those that are currently under-consumed-could be an effective strategy for improving diet quality across the UK population, say the researchers, especially among groups at higher risk of diet-related diseases.
Looking ahead, the researchers have been awarded £1.5 million from the Biotechnology and Biological Sciences Research Council (BBSRC) to conduct a randomised controlled trial. This new research will further determine how increasing plant food diversity impacts gut and cardiometabolic health and aims to support more targeted and practical public health recommendations to optimise diets and improve health.
