Note: The health benefits and concerns discussed here are not necessarily associated with all types of bread; there is considerable variety among different products in terms of their ingredients (e.g., presence or absence of wheat, addition of certain beneficial fibers, whole-wheat vs. white, etc.).

Atherosclerosis

Regular consumption of whole-grain foods is associated with an approximate 26% risk reduction of coronary heart disease. In general, soluble fiber (of which oats are a good source) is the dietary fiber most linked to a reduction of cholesterol levels. For unknown reasons, however, diets higher in insoluble fiber (found in whole grains and vegetables and mostly unrelated to cholesterol levels) have been reported to correlate better with protection against heart disease in both men and women. Some trials have used 20 grams of additional dietary fiber per day for several months to successfully lower cholesterol.

Constipation

Fiber, particularly insoluble fiber, is linked with prevention of chronic constipation. Insoluble fiber comes mostly from vegetables, beans, brown rice, whole wheat, rye, and other whole grains. Switching from white bread and white rice to whole-wheat bread and brown rice often helps relieve constipation. It is important to drink lots of fluid along with the fiber—at least 16 oz (480 ml) of water per serving of fiber. Otherwise, a “dry sponge” is now in the system, which can worsen the constipation.

Crohn’s disease

Some people with Crohn’s disease have food allergies and have been reported to do better when they avoid foods they are allergic to. One study found that people with Crohn’s disease are most likely to react to cereals, dairy, and yeast. Increasingly, baker’s yeast (found in bread and other bakery goods) has been implicated as a possible trigger for Crohn’s disease. Yeast is high in histamine, which is secreted during an allergenic response. People with Crohn’s disease lack the ability to break down histamine at a normal rate, so the link between yeast and Crohn’s disease may not be coincidental. However, the allergy theory cannot account for all, or even most, cases of Crohn’s disease.

Diabetes

Eating carbohydrate-containing foods, whether high in sugar or high in starch (such as bread), temporarily raises blood sugar and insulin levels. The blood sugar-raising effect of a food, called its “glycemic index,” depends on how rapidly its carbohydrate is absorbed. People eating large amounts of foods with high glycemic indices have been reported to be at increased risk of type 2 diabetes. On the other hand, a high-fiber diet (providing 50 grams of fiber per day) has been shown to work better in controlling diabetes than the diet recommended by the American Diabetes Association (ADA) (which provides 24 grams of fiber per day), and may control blood sugar levels as effectively as oral diabetes drugs. Moreover, people eating the high-fiber diet experienced significant reductions in total cholesterol, triglycerides, and LDL (“bad”) cholesterol compared with those eating the ADA diet. They also had slight decreases in glycosylated hemoglobin, a measure of chronically high blood glucose levels.

Heart attack

A high-fiber diet, particularly soluble fiber (high in oats, psyllium seeds, fruit, vegetables, and legumes), is associated with decreased risk of both fatal and nonfatal heart attacks, probably because these fibers are known to lower cholesterol. However, large trials separately studying men and women who were followed for years, have linked the greatest protection to insoluble fiber (from whole grains, breads and cereals), though scientists have yet to understand why. Until the details are better understood, doctors often recommend increasing intake of fruit, vegetables, beans, oats, and whole grains.

High cholesterol

Soluble fiber from oats and psyllium seed has lowered cholesterol levels in most trials. Doctors often recommend that people with elevated cholesterol eat more of these high soluble fiber foods, which are sometimes added to breads and other baked goods. However, even grain fiber (which contains insoluble fiber and does not lower cholesterol) has been linked to protection against heart disease, though the reason for the protection remains unclear. It makes sense for people wishing to lower cholesterol levels and reduce their risk of heart disease to consume more fiber (all types).

Oat bran is rich in a soluble fiber called beta-glucan. In 1997, the U.S. Food and Drug Administration passed a unique ruling that allowed oat bran to be registered as the first cholesterol-reducing food at an amount providing 3 grams of beta-glucan per day, although some evidence suggests this level may not be high enough to make a significant difference. Several trials have shown that oat bran supplementation can significantly lower cholesterol levels in people with elevated cholesterol, but only weakly in people with healthy cholesterol levels. Breads containing oat bran may, therefore, be beneficial at lowering elevated cholesterol.

Insomnia

Doctors sometimes recommend eating a high-carbohydrate food before bedtime, such as a slice of bread. Eating carbohydrates can significantly increase levels of a neurotransmitter (chemical messenger in the brain) called serotonin, which is known to reduce anxiety and promote sleep.

Irritable bowel syndrome

Limited research has suggested that fiber might help people with IBS. However, most studies find that IBS sufferers do not benefit by adding wheat bran to their diets and some feel worse as a result of wheat bran supplementation. It has been suggested that the lack of positive response to wheat bran may result from wheat sensitivity, which is one of the most common triggers for food sensitivity in people with IBS. Rye, brown rice, oatmeal, barley, vegetables, and psyllium husk are good sources of fiber and less likely to trigger food sensitivities than is wheat bran. Except for psyllium, little is known about the effects of these other fibers in people with IBS.

Multiple sclerosis (MS)

Some people with MS avoid gluten (a protein found in wheat, rye, oats, and barley) in hopes of diminishing symptoms, because a preliminary study reported that consumption of grains (bread and pasta) was linked to development of MS. However, another trial found an association between eating cereals and breads and reduced MS risk. Other researchers have found gluten sensitivity to be no more common among individuals with MS than among healthy people. Therefore, the idea that avoiding gluten will help MS remains speculative.

Rheumatoid arthritis (RA)

In one trial lasting 14 weeks, a pure vegetarian (vegan), gluten-free (no wheat, rye, or barley) diet was gradually changed to permit dairy, leading to improvement in both symptoms and objective laboratory measures of disease.

Weight loss and obesity

As noted earlier, foods containing high amounts of carbohydrate are sometimes measured on a scale called the glycemic index (GI). Eating foods with a high GI (e.g., white bread) promotes a more rapid return of hunger and increases subsequent intake of calories compared to eating similar foods with a lower GI (e.g., oat bran bread). Regular substitution of lower-GI foods, such as whole grains, for higher-GI refined foods may thus help prevent excess weight gain.