Whole grain vs. whole wheat: Which bread is healthier?

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No doubt you already know that whole grain bread is nutritionally-superior to white bread. It has more fibre, protein, vitamin E, vitamin B6, magnesium and potassium.

But the task of choosing between whole wheat, whole grain or pumpernickel, for example, isn’t as clear-cut. With healthy-sounding names and, often darker-coloured loaves, it’s not readily apparent if one is better for you than another.

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What’s the difference between whole wheat and whole grain bread? Is one more nutritious? How does sourdough bread rate? Here’s what to know to seek out a healthy loaf of bread.

What are whole grains?

Whole grain kernels are made up of three parts: the bran, the germ and the endosperm, each delivering valuable nutrients.

The bran layer is filled with fibre, B vitamins and minerals. The germ provides B vitamins, healthy fats, vitamin E and protective phytochemicals. The endosperm contains the grain’s starchy carbohydrates, plus a little protein and some vitamins.

When whole grains are processed into refined (white) flour, all that’s left is the starchy endosperm.

A higher intake of whole grains is tied to protection against type 2 diabetes, heart disease, stroke, colorectal cancer and, recently, aging-related increases in waist circumference.

Examples of whole grain foods include wheat berries, spelt berries, farro, freekeh, millet, sorghum, buckwheat, oats and brown rice.

Breads labelled “100 per cent whole grain” contain only whole grain flours and, as such, also deliver the nutritional benefits of the bran, germ and endosperm components.

What is the difference between whole wheat and whole grain bread?

Bread that is 100 per cent whole wheat is made with whole wheat flour; it doesn’t contain any refined flours. Surprisingly, though, that doesn’t mean “100 per cent whole wheat” bread is a whole grain bread.

To prolong the shelf-life of whole wheat flour, Canada’s Food and Drug Regulations allow up to 5 per cent of the whole wheat kernel – equivalent to roughly 70 per cent of the nutrient-rich germ – to be removed before milling. (Before milling whole wheat flour, the three parts of the grain kernel are separated and then recombined.)

A loaf of 100 per cent whole wheat bread, therefore, may not be whole grain. Look for 100 per cent whole wheat breads that list “whole grain whole wheat flour including the germ” on the ingredient list.

Whole wheat bread (germ included or not) has a high glycemic index, like white bread does. Because whole wheat flour is finely milled, whole wheat bread is more quickly digested and, as a result, causes a sharper and higher rise in blood sugar compared to denser whole grain breads.

Still, whole wheat bread is more nutritious than refined white bread.

Read labels on rye bread

Whole grain rye and pumpernickel breads are healthy choices. They offer a good source of insoluble fibre (the type that helps prevent constipation) and low-glycemic carbohydrates.

But many rye breads found in the grocery store bread aisle, as healthy as they may sound, don’t deliver whole grains.

Scan ingredient lists and you’ll see that many list wheat flour as the first ingredient followed by rye flour, both refined flours. Whole rye flour, rye meal, rye kernels and rye flakes indicate the presence of whole grains.

How does sourdough compare to whole wheat or whole grain bread?

Traditional sourdough bread is made from a slowly fermented mix of flour and water. Fermentation of sugars in the flour by bacteria and yeasts produce acids, which impart nutritional benefits.

Sourdough fermentation increases the amount of minerals available for the body to absorb. The acidic by-products of fermentation break down phytates, natural plant compounds that bind to calcium, magnesium, iron and zinc.

Fermentation also results in a low glycemic index. And it may make sourdough bread easier to digest by breaking down some of its gluten. (People with celiac disease, though, must avoid sourdough breads made with gluten-containing flours.)

Another benefit: fermentation transforms some of the flour’s carbohydrates into prebiotics, carbohydrates that nourish beneficial gut microbes.

To gain the nutritional benefits of both fermented sourdough and whole grains, read labels. Whole grain rye and sprouted whole grain breads are often made with a sourdough starter.

Or, like I do, check out the whole grain sourdough breads available at your local artisan bakery.

Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD