Whole grains are a source of multiple nutrients and dietary fiber, recommended for children and adults in several daily servings containing a variety of foods that meet whole grain-rich criteria.
By supplying high dietary fiber content, as part of a general healthy diet, consumption of whole grains is associated with lower risk of several diseases, including coronary heart disease, stroke, cancer and type 2 diabetes, with lower all-cause mortality. Regular whole-grain consumption lowers LDL and triglyceride levels, which contributes to an overall 26% reduction in coronary heart disease-risk factors. In addition, whole-grain consumption is inversely related to hypertension, diabetes, and obesity when compared to refined grains, all of which are negative indicators in total cardiovascular health.
As components of breakfast cereals, whole grains are associated with improved micronutrient intake and lower risk of several diseases. Their effects on gastrointestinal health, risk of obesity and cognition need further evaluation.
Keeping grains as close to their original form as possible slows or prevents the digestion of starch, and a slower digestion is responsible for preventing spikes in blood sugar (over time spikes in blood sugar may lead to insulin resistance).
Cereals proteins have low quality, due to deficiencies in essential amino acids, mainly lysine. Supplementation of cereals with proteins from other food sources (mainly legumes) is commonly used to compensate for this deficiency, since the limitation of a single essential amino acid causes the others to break down and become excreted, which is especially important during the period of growth. In contrast, the proteins of the pseudocereals have a high nutritional value, close to those of casein (the main protein in milk). Quinoa and amaranth are the most nutritious grains due to their high content and quality of proteins, with high levels of lysine and other essential amino acids. Minor cereals and pseudocereals are a good alternative to replace gluten-containing cereals, for people who need to follow a gluten-free diet.
Manufacturers of foods containing whole grains in specified amounts are allowed a health claim for marketing purposes in the United States, stating: "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" and "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". The scientific opinion of the European Food Safety Authority (EFSA) related to health claims on gut health/bowel function, weight control, blood glucose/insulin levels, weight management, blood cholesterol, satiety, glycaemic index, digestive function and cardiovascular health is "that the food constituent, whole grain, (...) is not sufficiently characterised in relation to the claimed health effects" and "that a cause and effect relationship cannot be established between the consumption of whole grain and the claimed effects considered in this opinion."