Barley is an excellent source of both soluble and insoluble fibre. Two different rat studies have indicated significant benefits from consuming Barley in your diet. The first, demonstrated that Barley increases bowel movement and relieves constipation (which reduces your risk of bowel cancer), and the second showed that in rats with existing colon cancer, the group fed on Barley had significantly fewer tumours than the other groups.
This could be due to the effects of the fibre enabling the colon to function correctly, or it could be due to a number of the other anti-cancer compounds found within the Barley including beta-glucans, which aid in immune function and help to lower cholesterol. Other antioxidants, including selenium, quercetin and phenolic acids have all been shown to help reduce cell damage from free radicals, and exert an anti-cancer effect.
To include Barley in your diet, you can replace anywhere up to 50% of the wheat flour you use with Barley flour (although I would advocate you eliminate wheat from your diet altogether if possible), or else you can add cooked Barley to other foods such as soups and salads. Barley flakes are a very simple addition to breakfast cereal.