High bread intake associated with reduced risk for cancer mortality

Key takeaways:

• Among 18 studies, more than 93% of RRs indicated no association or a lower risk for cancer in the highest bread intake group.
• A researcher cautioned that the study lacked data on white bread intake.

BOSTON — A recent study showed that high bread consumption was not associated with an increased risk for cancer. Instead, a researcher found that it was linked to a lower risk for colorectal cancer incidence and total cancer mortality.

California’s Proposition 65 — a legislative law on toxic enforcement — lists several chemicals that are carcinogenic to humans. These include acrylamide, which “has shown to be present in baked goods, particularly baked goods that are toasted,” according to Glenn Gaesser, PhD, a professor at Arizona State University.

“There’s a concern that acrylamide presence in bread, because it’s so widely consumed worldwide, could pose a risk,” he told Healio. “That’s one of the reasons I did this study, to focus on bread.”

To assess potential associations between various kinds of bread and cancer risk, Gaesser performed a categorical meta-analysis of 18 prospective cohort studies that provided RRs for bread consumption and cancer mortality or incidence.

Gaesser found that bread consumption was not associated with a higher cancer risk, with more than 93% of 75 RRs indicating no association or a lower risk in the highest intake group.

The group with the highest intake of bread had an 11% (HR = 0.89; 95% CI, 0.81-0.97) reduced risk for cancer mortality as well as a 10% (HR = 0.9; 95% CI, 0.81-1) reduced risk for colorectal cancer incidence.

“That could be due to a number of things, because you’re consuming it and your colon is going to be exposed to that, and the whole grain or whole meal bread has higher fiber,” Gaesser said. “Fiber has been shown to accelerate the movement time through the gastric system so there’s less exposure to potential carcinogens, which also produce a lot of short-chain fatty acids.”

He pointed out several limitations to the analysis, which included the studies being observational and not having been controlled well for other possible confounding factors.

“For example, glycemic index has been shown to be associated with certain types of cancers. I think only one study that I looked at controlled for glycemic index,” Gaesser said. “Diet fiber was not controlled for in a number of the studies. Physical activity was not controlled for.”

Additionally, “most of the studies looked at whole grain, whole wheat or whole meal and showed the lower risk,” Gaesser said.

“One of the research gaps that needs to be addressed is looking at white bread itself, or rich refined grain bread, because there was a lack of evidence on that to form any definitive conclusions,” he said.

References:

• Gaesser G. Bread consumption and cancer risk: Meta-analysis of prospective cohort studies. Presented at: NUTRITION; July 22-25, 2023; Boston.
• Proposition 65. https://oehha.ca.gov/proposition-65. Accessed July 23, 2023.