What Foods Are Considered Bulk Foods?

Bulk foods are foods with a high dietary fiber content. Fiber is the indigestible substance found in fruits, vegetables and grains, and it provides an increased volume of digestive matter. This volume promotes a feeling of fullness, which can be helpful if you are trying to reduce calorie intake. Additionally, bulk foods play an important role in regulating the digestive system by reducing constipation and increasing the production of good bacteria in the colon. The good bacteria promote health in other areas of the body such as immune system improvement, controlled cholesterol and triglyceride levels, and possibly the prevention of certain cancers.

The two general categories of dietary fiber in bulk foods are soluble fiber and insoluble fiber. Insoluble fiber retains water and softens stool, which helps your body eliminate potential toxins and carcinogens. Soluble fiber dissolves in water and is fermented by colon bacteria, providing them with nutrients and improving your digestive function. A certain type of soluble fiber--prebiotic soluble fiber--may be the most beneficial in improving immune function and blood lipid profile, and promoting weight loss via enrichment of your colon bacteria.

Your colon has several trillion bacteria, which contain more than 100 times the number of genes that the human body has. Your makeup of bacteria is as unique as your DNA; however, increasing your fiber intake can help alter this bacteria profile. The fiber in bulk foods increases the proliferation of good colon bacteria, which produce vitamins and enzymes, train the immune system to respond properly, and help destroy harmful colon bacteria.

Most plant fiber sources have both soluble and insoluble fiber, although the relative proportion of each varies. Apples, oranges, potatoes and oats have a relatively high soluble fiber content, whereas insoluble fiber dominates such foods as bran cereal, corn and kidney beans. Top sources of prebiotic soluble fiber include onions, garlic, artichokes, asparagus and yams. You should aim to eat about 25 to 35 grams of total fiber per day. However, you should gradually increase to this amount to prevent excessive bloating and gas that could come from sudden fiber increases.

Increased awareness of the health benefits of high-fiber bulk foods has led food manufacturers to add fiber to their otherwise highly refined cereals and breads or to foods that do not typically contain fiber, such as yogurt. Although these added fibers are most likely safe, more research is needed to determine if they deliver the same bulk-providing benefit as unrefined foods, and whether some types of fibers may be more beneficial than others. Since these refined foods are generally lower in vitamins and minerals, it is more beneficial to eat the whole, natural foods from an overall nutritional standpoint.