Administration allows claims to be made for the health benefits of consuming wholegrains in relation to both cancer prevention and heart disease. For example:
- Low-fat diets rich in fiber-containing grain products, fruits, and vegetables may reduce the risk of some types of cancer, a disease associated with many factors.
- Diets low in saturated fat and cholesterol and rich in fruits, vegetables, and grain products that contain some types of dietary fiber, particularly soluble fiber, may reduce the risk of heart disease, a disease associated with many factors.
There are also specific health benefits claimed for certain cereals such as oats, rye, and barley, which will be considered below.
Certain cereals may cause adverse reactions in some people because of their sensitivity to proteins in the grain. The most important of these is gluten-sensitive enteropathy; or celiac disease. Gluten is the main protein complex in wheat bread, and gliadins, (components of this protein), together with similar protein fractions in rye and barley (and possibly oats), cause reactions in the lining of the small intestine which destroy the absorptive surface of the gut. In young children or severe cases, vomiting, diarrhea, and malabsorption will result, although in older children and adults the gastrointestinal symptoms are often slight or absent. The person may simply complain of excess flatulence or intermittent abdominal pain, and constipation is not uncommon. However, damage is still being done to the small intestine, and there may be hidden malabsorption of certain vitamins and minerals which can result in anemia or bone disease in the long term. There is an associated skin disease, dermatitis herpetiformis, which also results in changes in the gastric mucosa. The treatment for both of these conditions is a gluten-free diet. This requires complete avoidance of the cereals containing gluten and gliadin-like protein fractions, i.e. wheat, barley, triticale, and rye. There is some controversy over the need to eliminate oats from the diet, as some people appear to be intolerant to this while others are not. Buckwheat, despite the name, is not a true cereal and does not contain gluten.
There are people without celiac disease or dermatitis herpetiformis who appear not to tolerate wheat or some other cereals, and find that either adverse gastrointestinal symptoms such as irritable bowel syndrome or other signs of food intolerance such as asthma, eczema, or migraine are alleviated by removing these from the diet.