A new study comparing historic and modern wheat varieties has shown an increase in dietary fiber and a decrease in acrylamide, indicating that white bread is not as unhealthy as it has often been portrayed. Published in the journal Scientific Reports, researchers report “a great deal of variation between years” – suggesting that environmental conditions such as rain or drought also affect nutritional quality, but that this is small when compared to the effect of the variety. The findings are contrary to concerns that the push for higher yields has made today’s wheat less “healthy” than older types.
The 39 wheat varieties, in use since 1790, were grown for three consecutive years at Rothamsted Research in the UK – and is the world’s longest running experiment. The project was funded by UKRI BBSRC, a body which works in partnership with universities, research organizations and government, and also involved staff from the University of Bristol.
“Commercial wheat breeding has, over the years, focused on yield, processing quality and disease resistance. It is good to know that during this process other components, important for human health, have not been negatively affected as a result of this,” lead author Dr. Alison Lovegrove tells FoodIngredientsFirst.
“Fiber plays an important role in how much water flour absorbs. But also, people are more aware of health issues now. Dietary fiber is something we don’t eat enough of, it’s good to know that white flour from modern high-yielding wheats used by industry does contain more fiber than in the past,” she asserts.
For the purposes of the analysis, the 39 wheats were split into three groups – nine which were bred in the years 1790-1916, before an understanding of genetics had been developed; 13 varieties came from 1935-1972, recognized 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 that the content of dietary fiber has increased steadily over the past two centuries, with modern varieties containing, on average, about a third higher concentration of the major fiber component, the cell wall polysaccharide, arabinoxylan.
When addressing ingredients that have been “demonized,” Dr. Lovegrove states that “all refined products have probably had a bad reputation.” The global rise in obesity and chronic diseases such as Type 2 diabetes has been blamed on processed food, such as white bread. “Clearly the over-consumption of processed foods is a problem, but, for example, some minerals and more soluble fiber are more bioavailable in white bread than in wholemeal,” she explains.
A turning point for wheat flour?
These findings could potentially be a turning point. “It may go some way to address concerns that the push for higher yields has not made modern wheat less ‘healthy’ than wheat from the past,” Dr Lovegrove states.
The stimulus for the study, according to Dr. Lovegrove, was that the great increase in wheat yields brought about by the introduction of dwarf wheat varieties in the 1960s 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.”
The role of fiber
Fiber-fortified foods and ingredients continue to gain traction in industry. This may be significant for consumers, because fiber is deficient in UK diets with about 10 percent of the intake coming from white bread.
In February, FoodIngredientsFirst reported that high fiber white bread could be available by 2025. An international group of scientists also led by Dr. Lovegrove at Rothamsted Research and the John Innes Centre successfully opened the door to healthier white bread, after they pinpointed genes responsible for the dietary fiber content of flour. The high fiber white flour has as much as twice the fiber of traditional white flour, the researchers claimed at the time.
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, highlights Dr. Lovegrove.
“In fact, we found increasing trends in several components, notably the major form of dietary fiber. This is despite great increases in the yields of wheat grown over this period.”
The team also found the concentration of betaine, which is beneficial for cardiovascular health, has increased, while levels of asparagine – which can be converted to the potentially cancer-causing chemical acrylamide when bread is baked – have decreased. The amount of certain sugars, including sucrose, maltose and fructose, have also increased over this period, the researchers flag.
The increase in betaine may also be beneficial to health. The modified amino acid is key in several metabolic pathways and has been found to help protect internal organs and improve heart health.
“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 continues. “Processing may well have changed and that may have affected the foods we eat, but the quality of the raw material [wheat] is probably better than it ever was,” she concludes.