White flour is the healthiest it has been in 200 years, a new study by Rothamsted Research in Hertfordshire has revealed.

The research saw historic and modern wheat varieties grown side by side to address concerns that the push for higher yields had made today’s wheat less healthy than older types. A total of 39 wheat varieties, spanning a period of 230 years, were grown for three years running for the study.

“Despite concerns over the declining genetic variation found across modern wheat types, there is no evidence that the health benefits of white flour from wheat grown in the UK have declined significantly over the past 200 years,” said lead author Dr Alison Lovegrove.

“In fact, we found increasing trends in several components, notably the major form of dietary fibre. This is despite great increases in the yields of wheat grown over this period.”

Rothamsted Research said this could be significant to consumers as fibre is deficient in UK diets, with about 10% of the intake coming from white bread.

However, following recent research by the centre, along with a group of international scientists and the John Innes Centre, they were able to create a white loaf with double the amount of fibre in it after identifying the parts of the wheat genome that controlled the fibre content of white flour.

As well as an increase in dietary fibre, the latest research showed the concentration of betaine, which is beneficial for cardiovascular health, had also risen, while levels of asparagine – which can be converted to potentially cancer-causing chemical acrylamide when bread is baked – had fallen.

However, the amount of certain sugars, including sucrose, maltose and fructose, had also increased over this period.

Dr Lovegrove said the stimulus for the study was that the great increase in wheat yields, brought about by the introduction of dwarf wheat varieties in the 1960s, had also led to a decline in zinc and iron concentrations.

“What was less clear was the impact on other components of nutrition. In addition, many studies look only at wholemeal flour, but by far and away white flour products are the ones most people eat,” she added.

For the purposes of the analysis, the 39 wheats were split into three groups – nine bred in the years 1790-1916, before an understanding of genetics had been developed; 13 varieties came from 1935-1972, recognised as a period of increasing scientific understanding; and 17 cultivars that were bred using modern breeding techniques between the years 1980 and 2012.

After milling the grain to white flour, the researchers found the content of dietary fibre had increased steadily over the past two centuries, with modern varieties containing, on average, about a third higher concentration of the major fibre component, the cell wall polysaccharide, arabinoxylan.

Writing in the journal Scientific Reports, the team pointed to a great deal of variation between years – suggesting that environmental conditions such as rain or drought also affected nutritional quality, but that this was small when compared to the effect of the variety.

“There is a strong environmental effect on grain composition, which must therefore be taken into account when comparing crops grown at different times or at different places. This is a limitation of many studies that have previously looked at the change in nutritional quality of our food through time,” Dr Lovegrove added.