When I was growing up, my mother never allowed white bread in the house. She said white bread was unhealthy, and thus all our bread had to be whole-wheat. My mother was not the most health-conscious person in the world — she served pigs in a blanket and boxed macaroni and cheese more often than was probably advisable — but white bread was the line in the sand she would not cross.
But now it looks like whole-wheat bread might not actually be healthier than white bread at all.
The idea that whole-grain bread is better for you than white bread has been a nearly universally accepted bit of nutrition advice for decades. But now that tenet is being called into question by the team behind Modernist Bread: The Art and Science. Research for that book involved four years of deep analysis by Nathan Myhrvold and Chef Francisco Migoya and a team of historians, scientists, grain experts, and bakers. After all that, Myhrvold told Bon Appetit that there's no real evidence that whole-wheat bread is intrinsically healthier than white.
"If you made a list of what everybody knows to be true about nutrition, one of those things would be that whole-grain breads are both more nutritious and better for you, health-wise," Myhrvold said. "And, unfortunately, there's no evidence of either one, and kind of evidence to the contrary."
The key difference between white and whole-wheat bread is way the grain is processed into flour before baking. Every grain has an outer and an inner part. The outside part is the bran, and the inside part of the grain contains a germ and endosperm. To make white flour, the endosperm is separated from the bran and germ, ground up, and turned into flour. Whole-wheat flour also contains the ground-up germ and bran, as well as the endosperm.
For decades, it has been assumed that the whole-wheat bread is healthier because the bran and germ contain fiber and vitamins that the endosperm by itself does not have.
But the Modernist Bread team looked at 50 years of health and nutrition studies, and Myhrvold says human digestion doesn't break down the whole wheat the way chemical analysis in a lab does, and that means our bodies don't actually absorb many of the vitamins and minerals from whole-wheat bread.
In fact, Myrhvold says there's a compound in bran that can actually cause an "antinutrient effect" by binding to beneficial minerals and keeping them from being absorbed by the body.
Whole-wheat bread also has more fiber, because of the bran, and that has been touted as having significant health benefits. The fiber in whole-wheat bread is supposed to make a person's body break down starches more slowly and prevent glucose spikes. Myrhvold, however, says there's not actually enough fiber in whole-wheat bread to make that happen at a significant rate, and he says whole-wheat bread and white bread have basically the same effect on a person's body.
That's not to say that there's no reason to eat whole-wheat bread, of course. The chewy texture and rich, nutty flavor of good whole-wheat bread is more than enough reason to keep it around. But it looks like we may have been way too harsh with white bread, and maybe we were too quick to kick it out of the pantry in favor of whole-wheat bread after all.