Most people believe brown bread is healthier – but this study shows it is not that clear-cut.
Medically reviewed by Dr Louise Wiseman MBBS, BSc (Hons), DRCOG, MRCGP and words by Natalie Healey
If you’ve been jumping on the bread baking wagon lately, you might be wondering: which is healthier, brown bread or white bread?
Most people believe brown bread, otherwise known as wholemeal or whole-wheat bread, is better for our health than white. And according to most nutritionists, you’d be correct. Wholegrain products contain more fibre and nutrients than their white counterparts.
However, it is not necessarily so clear-cut. A study in 2017 published in Cell Metabolism found no overall benefit in health measures for those who ate wholegrain sourdough bread over white. Some people did better on whole-wheat, while others benefited more from white bread. Researchers suggested ‘one size fits all’ dietary advice may not always be true.
Scientists from the Weizmann Institute of Science in Israel selected 20 healthy participants who ate bread regularly. They were divided into two groups to eat a specific amount of either white bread or wheat sourdough. This was for a week then there was a washout period and they tried the alternate bread for a week. The bread amounted to a quarter of their daily calories. The main aim of the study was to look at the effect on glucose and glucose handling in the body.
The researchers measured the participants glucose, fat and cholesterol levels. They found, contrary to popular belief that there were no clinically significant differences between the effects of the two types of bread.
Within the results different people seemed to react in different ways to the breads so it was suggested some results may have cancelled each other out in the data. The researchers said the results reflected the idea that general one-size-fit-all diets won’t work because people respond to the same foods differently – likely due to change in their gut bacteria.
“The findings for this study are not only fascinating but potentially very important, because they point toward a new paradigm: different people react differently, even to the same foods,” said Eran Elinav from the Weizmann Institute and another of the study’s senior authors.
“To date, the nutritional values assigned to food have been based on minimal science, and one-size-fits-all diets have failed miserably.”
Different people react differently, even to the same foods.
It is relevant to note that sourdough is thought to have many benefits whether as white or brown bread. It tends to have a higher protein and vitamin and mineral content than other breads (iron, b vitamins, selenium) and contains healthy bacteria due to the fermentation methods to create it. It is said to be easier on the digestive system and thus better for gut health. This study did not look long term at health effects.
This was a very small study and the subjects were only consuming each type of bread for a week. It would be wrong to dismiss all the valid research regarding the effects of whole grains on health and the possibility of additives and preservatives in very processed white bread causing potential harm. Good fibre sources such as wholewheat bread or sourdough help digestion and gut transit time allowing for absorption of nutrients from our food.
Professor Susan Jebb who studies diet and popular health at the University of Oxford said that it may have been too small a group to detect differences in response. She also pointed out that in the research paper itself, the investigators then looked at a different type of analysis – looking at the participants before and after consuming each type of bread. But since there is no control group, any of the changes seen may well be due to factors unrelated to the bread.
“People participating in trials commonly change their behaviour in a host of ways and if we ask people to change their diet by eating a certain amount of bread they may well make other changes in their diet too. It is just as likely that these changes, which have not been measured, may explain any changes observed. As such, it’s difficult to draw any robust conclusions.”
The long term effects of whole grains on health are well established.
And Dr Elizabeth Lund, an independent consultant in nutrition and gastrointestinal health stressed that this study does not mean people should give up on whole grains.
“It should not be forgotten that the health benefits of whole grains may be much longer-term than a one week study can show, especially in relation to gut health and prevention of conditions like bowel cancer. Therefore this study does not imply that people should give up eating whole grain foods based on these results.”
The long term effects of whole grains on health are well established and this one study would not be a reason to give them up but it opens up the dialogue that ‘one diet fits all’ may be an oversimplification.