Eating plenty of fruit, vegetables and grains is cheaper than other healthy diets, suggests new research.
It costs up to Â£1.40 a day less than the Mediterranean Diet and the US Healthy Diet, according to the study.
Three out of four British adults fail to get their '5-A-Day'. It has been claimed poor diets and obesity are directly caused by economic deprivation.
The latest findings were based on three typical two-week menu plans developed to meet the 2015-2020 Dietary guidelines for Americans.
The foods comprised meals, snacks and drinks and were all bought online.
The vegetarian version cost Â£11.50 (15.4 dollars) a day compared to Â£12.65 (17 dollars) for the US Healthy and Â£12.90 (17.3 dollars) for the Mediterranean.
Much less meat and poultry were consumed in the former than the latter two.
Most affordable menu
The researchers said: "This did not affect nutritional quality and may have contributed to making this the most affordable menu plan."
The findings, presented at the European Congress on Obesity in Austria, show that a veggie diet is not only good for you - it's the most affordable too.
Three-quarters of Americans also do not eat enough fruit and vegetables with most exceeding recommendations for added sugars, saturated fats and salt - just like the UK.
About half of all US adults have at least one preventable chronic condition such as obesity, cardiovascular disease and type 2 diabetes.
How to get people to eat more healthily at an affordable price has been debated for years.
Nearly seven in 10 Brits say they find healthy food and drinks more expensive when compared to other products.
So to answer how much healthy eating actually costs Dr Hilary Green and colleague Gary Sweeney from the NestlÃ© Research Center in Lausanne, Switzerland devised the menu plans.
Cost of health
Dr Green, of the NestlÃ© Research Centre, Lausanne, Switzerland, said: "Online shopping makes it convenient to buy foods for a nutritious diet that meets government recommendations, but it may be expensive.
"Even though a vegetarian menu plan may be more affordable than other healthy menu plans, $15.4 per day per person is still expensive.
"The United States Department of Agriculture has previously estimated that the daily cost of food for a healthy menu plan can be as little as $6.5 (Â£4.85) per day."
All products were sourced from Amazon Grocery and Gourmet Food which captures 26 per cent of the US online food and drinks market.
The researchers collected the cheapest prices excluding online sales, discounts and deals.
Results showed the average nutritional quality scores based on a validated scale were similar - vegetarian 85.3; US Healthy 84.3 and Mediterranean 82.4. But the former was found to be much cheaper.
Online grocery shopping sales in the US generated an estimated 7 billion dollars in 2017, and are predicted to reach almost 30 billion dollars by 2021. Currently, around a third of Americans buy their groceries online.
The menu plans were drawn up by calculating the dietary needs of an average 40 year old woman who was not pregnant.
The researchers pointed out a different consumer profile would affect the overall cost.
The Mediterranean diet is rich in fruits, vegetables, nuts, whole grains, and olive oil. It is low in red meat and other saturated fats, and it contains few processed foods or refined sugars.
The US Healthy diet is based on the 2015-2020 Dietary Guidelines for Americans and includes poultry and seafood as well as vegetables, fruit, grains and low fat dairy produce.
Last year a UK study by Institute of Economic Affairs found the Â£1 cost of a cheeseburger could also buy a kilo of sweet potatoes, two kilos of carrots or 10 apples.
It said healthier foods bought in supermarkets tend to have a smaller price tag than their unhealthier counterparts such ready meals or pizza.
It showed when measured by edible weight, a wide range of fruit and vegetables are available for less than Â£2.00 per kilogramme.
By contrast, the cheapest ready meals, chocolate, crisps and bacon cost more than Â£3 per kilogramme.
The researchers claimed the recommended five portions of fruit and vegetables a day could cost as little as 30p.