Why five-a-day might not be enough – and the number of plants you should be eating

Eating five fruits and vegetables a day might not cut it, research suggests, with those who eat 11 different plants a day proving to be healthier.

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, researchers from King’s College London found.

But eating a more diverse range of plant-based foods, such as fruit, vegetables, pulses and herbs, is associated with better heart and metabolic health.

Researchers found that a diverse diet improved cholesterol levels, blood sugar markers, better overall diet quality and higher intakes of key nutrients, including fibre, vitamins, and minerals.

Dr Eirini Dimidi, senior lecturer in nutritional sciences at King’s College London and senior author of the study, said: “Current dietary guidance in the UK often emphasises quantity, such as ‘five-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.”

The research, published in the journal Clinical Nutrition, analysed data on more than 670 adults from the UK National Diet and Nutrition Survey between 2016 and 2017.

Participants from the survey were split into three groups based on how many different plants they ate.

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 revealed that people who ate less of a variety of plants in their diet had lower HDL cholesterol, known as “good cholesterol”. Lower levels of this type of cholesterol could make you more likely to have a heart problem or a stroke.

They also found that HBA1C concentration – blood glucose levels – is lower for every one-unit increase in plant diversity.

However, the study also found that people who ate a variety of plants generally had a healthier lifestyle.

For example, only 6 per cent of people in the high-diversity group smoked, compared with 30 per cent in the low-diversity group.

They had also consumed more total sugar, likely due to greater intake of fruits and fruit juices. Although 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.

Researchers found vegetables were the largest contributors (21.0 per cent) to diversity, followed by plant-based fats and oils (18.8 per cent), and fruit (17.0 per cent).

Dr Dimidi said: “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.”

She added: “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.”

The British Nutrition Foundation highlights that adults should eat 30g of fibre a day – roughly the same amount as you can get from eating five fruits and vegetables a day or by eating 30 plants a week including nuts, seeds, beans and spices in addition to fruit and vegetables.

Nutritionist Kim Pearson, who specialises in weight loss, told The Independent: “Rather than just focusing on quantity, like ticking off five-a-day, we should also be thinking about variety. We know that eating a broader range of plant foods provides a wider range of nutrients and supports gut health, this study highlights how it may also impact metabolic health markers like blood sugar balance and blood lipid levels.

“The fibre and polyphenols found in different fruits, vegetables, pulses, nuts, seeds, and herbs all help to feed beneficial gut bacteria. A healthy microbiome is closely linked with metabolic health, immune function, and even mood. Aiming for eleven different plants a day is a great goal.

“This may sound like a lot, but simple strategies like adding a sprinkle of herbs, a mix of salad leaves, a handful of seeds, or trying a new vegetable each week can all help increase variety.”

Dietitian Dr Duane Mellor told The Independent: “This does not go against the idea of five-a-day, it just suggests we should vary the plants we eat. This goes beyond fruit and vegetables and includes herbs, seeds and pulses. Enjoying a variety of foods is key, perhaps more than focusing on eating a certain number.”