A whole grain is a grain of any cereal and pseudocereal that contains the endosperm, germ, and bran, in contrast to refined grains, which retain only the endosperm.
As part of a general healthy diet, consumption of whole grains is associated with lower risk of several diseases. Whole grains are a source of carbohydrates, multiple nutrients and dietary fiber.
Varieties
Whole grain sources include:
Cereals
Wheat (spelt, emmer, farro, einkorn, Kamut, durum) Rice (Black rice, brown, red, and other colored rice varieties) Barley (hulled and dehulled but not pearl) Maize or Corn Rye Oats (including hull-less or naked oats)
Minor cereals
Millets
Sorghum
Teff
Triticale
Canary grass
Job's tears
Fonio, black fonio, Asian millet
Wild rice
Pseudocereals
Amaranth
Buckwheat, Tartary buckwheat
Quinoa
Health effects
Nutrition
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. 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.
Cereal 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.
Disease risk
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 or bowel function, weight control, blood glucose and insulin levels, weight management, blood cholesterol, satiety, glycemic 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."
By supplying high dietary fiber content, as part of a general healthy diet, consumption of whole grains may lower risk of several diseases, including coronary heart disease, stroke and cancer, with lower all-cause mortality. Regular whole-grain consumption may lower elevated LDL and triglyceride levels, which are risk factors for cardiovascular diseases. Whole grain consumption is associated with a lower risk of type 2 diabetes.
In 2012, Health Canada stated that "the evidence to date from clinical trials and prospective cohort studies was not sufficient to support a whole grains and coronary heart disease risk reduction claim in Canada". A 2017 review of clinical trials found insufficient evidence for a relationship between whole grain consumption and lowered risk of cardiovascular diseases.
The American Institute for Cancer Research and World Cancer Research Fund International have stated that there is strong evidence that whole grains decrease risk of colorectal cancer.