Break Bread — But Not Just Any Bread — at Breakfast

CBS study finds sourdough bread tops, whole wheat on the bottom when it comes to daily health benefits


Choose your bread wisely because the type of bread you eat for breakfast can affect how your body responds to lunch, a U of G researcher has found.

Prof. Terry Graham, Human Health and Nutritional Sciences, studied four types of breads to determine which have the most positive health effects when it comes to carbohydrate metabolism, blood sugar and insulin levels.

“There's an urban myth that if you want to lose weight, you should not eat bread,” says Graham, “but the truth is, bread is one of our biggest sources of grains and has a number of healthy benefits. With this study, we wanted to find out which breads are better, so we can optimize the benefits by combining them into one type of bread.”

Using white, whole wheat, whole wheat with barley and sourdough white breads, Graham and a team of researchers examined how subjects responded just hours after eating the bread for breakfast and again just hours after eating a standard lunch.

The subjects, who were overweight and ranged between 50 and 60 years of age, showed the most positive body responses after eating sourdough white bread, and those positive responses remained even after eating a second meal that didn't include the bread.

“With the sourdough, the subjects' blood sugar levels were lower for a similar rise in blood insulin,” says Graham, whose findings have been submitted to the British Journal of Nutrition. “What was even more interesting was that this positive effect remained during their second meal and lasted even hours after. This shows that what you have for breakfast influences how your body will respond to lunch.”

He says it's likely that the fermentation of the sourdough changes the nature of the starches in the bread, creating a more beneficial bread.

In contrast, the whole wheat bread varieties used in the study came out on the bottom — even below white bread. The whole wheat breads caused blood sugar levels to spike, and these high levels lasted until well after lunch.

Graham says the less positive blood responses sparked by the whole wheat are likely due to the fact that the milling process involved in making the whole wheat bread used in the study is similar to that used for white bread. This is not the case with all whole wheat or whole grain breads, he adds.

“The parts of the grain like wheat germ and bran that have the health benefits are taken out to create white flour and then partially added back in to make whole wheat. Based on the findings of this study, as well as a followup study using whole grain rather than whole wheat, we are learning that the best way to get these nutrients is through a whole grain bread, not whole wheat.”

The results of this study, which was funded by the Ontario Ministry of Agriculture, Food and Rural Affairs, have led Graham and a team of researchers to continue examining the healthy benefits of sourdough bread and whole grain.

In collaboration with Markham bakery Stonemill Bakehouse, they have developed a whole grain sourdough bread and are currently testing its long-term health benefits on subjects. They're comparing the results with the subjects' responses to a standard white bread.

Besides measuring blood and metabolic responses, the team is looking at cholesterol levels to see if the whole grain sourdough bread can reduce cholesterol levels when eaten over a long period. They're also studying how genetic makeup can influence the way a person responds to different breads.

Subjects are still needed for this study. The researchers are looking for men and post-menopausal women who are overweight, not diabetic and not on medication to control cholesterol or triglyceride levels.

For more information, call Ext. 56967 or send e-mail to bread@uoguelph.ca.