Plant-based diet diversity linked to better heart and metabolic health, UK study finds

Researchers at the UK’s Department of Nutrition suggest that eating a more diverse range of plant-based foods leads to better cardiometabolic health results, mitigating the risk of cardiovascular diseases and type 2 diabetes.

These outcomes include improved cholesterol levels, blood sugar markers, and higher intakes of key nutrients, including fiber, vitamins, and minerals.

The researchers note that the importance of diet in preventing and managing conditions like cardiovascular disease and type 2 diabetes is well established. However, they say their study is the first of its kind to examine how many and which types of plant foods UK consumers eat.

Their research tracked over 670 adults from the UK National Diet and Nutrition Survey (NDNS) from 2016–2017, with 97% actively following an omnivorous diet.

“Current dietary guidance in the UK often emphasizes quantity, such as ‘five-a-day’ for fruit and vegetables,” says Dr. Eirini Dimidi, senior lecturer in Nutritional Sciences at King’s College London and senior author of the study.

“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.”

One key finding of the paper is that people in the UK do not consume enough plants. The median is eight different plants a day — including spices and fat-based oils — with some eating just two daily.

Categorizing diet diversity

In their study published in Clinical Nutrition, the researchers grouped participants into three categories based on the variety of plant-based foods they consumed each day. 

One key finding of the paper is that people in the UK do not consume enough plants.Participants 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 revealed that those 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.

The researchers also found that HBA1C concentration — reflecting average blood glucose levels — was lower for every one-unit increase in plant diversity.

They also observed 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.

Meanwhile, participants in the high-diversity group also had better blood lipid profiles and met more fiber recommendations compared to the low and moderate groups. Overall, they consumed more total sugar, which was likely due to their more frequent consumption of fruits and fruit juices.

Excess sugar can have negative health effects, but the researchers note that fruits provide additional beneficial nutrients such as fiber and antioxidants. These may help offset sugar’s negative impacts on blood sugar and overall health.

“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, and legumes, despite their established nutritional benefits, contributed minimally to total intake,” says Dimidi.

“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 fiber and several micronutrients, which are important for maintaining a strong immune system and healthy bones and tissues.”

Add-ons to boost diversity

Next to fruits and vegetables, the researchers underscore that legumes, nuts, seeds, herbs, and spices are ideal plant-based food sources that increase dietary plant diversity.

“Try adding nuts to your porridge and 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,” says Dimidi.

The team was awarded £1.5 million (US$2 million) from the Biotechnology and Biological Sciences Research Council to conduct a randomized controlled trial. This upcoming research will investigate how increasing plant food diversity impacts gut and cardiometabolic health.