Rice is a staple food for over half of the world's population. Eighty percent of the British population buy rice, predominantly white rice, with the average person consuming approximately 5.6 kg per year. Rice consumption in the UK is expected to increase slightly, as a result of the growing ethnic population and food diversification. Starchy foods such as rice, potatoes, bread and cereals are our main source of carbohydrate and play an important role in a healthy diet. As well as providing energy, rice contains other essential nutrients such as thiamine, riboflavin, niacin, vitamin E, zinc, potassium, iron and fibre. On cooking, rice swells to at least three times its original weight and therefore benefits from a low-energy density compared to other starchy carbohydrate foods (e.g. bread), as well as a low-sodium content (unless salt is added to rice products). It has a low allergenicity and is relatively easy to digest, making it a useful food for early weaning or during convalescence.
The Department of Health encourage the selection of wholegrain versions of starchy carbohydrate foods as these are higher in fibre. Brown rice also has a higher proportion of important bioactive phytochemicals such as hemicelluloses and lignans with antioxidant and anti-inflammatory properties that may benefit health.
Despite the common perception that starchy carbohydrate foods are ‘fattening’, diets containing rice have been shown to achieve weight loss in obese subjects, although greater weight reduction has been shown with mixed rice compared with white rice. Although the reported glycaemic index (GI) of different rice varieties is inconsistent, most types of rice are classified as low or medium ‘GI’ foods but this is influenced by cooking time, the degree of gelatinisation and rice type. While there are numerous studies that have examined the link between high-carbohydrate intakes and risk of chronic diseases such as obesity, type 2 diabetes and cardiovascular disease, relatively few have investigated the role of rice specifically, particularly in western populations. In Asian populations in whom rice is a staple food, higher white rice consumption has been associated with elevated risk of diabetes and metabolic syndrome. Some prospective cohort studies in the US have linked regular consumption of white rice with higher risk of type 2 diabetes, whereas brown rice intake was associated with lower risk. These studies were however observational in nature and so cannot determine a ‘cause and effect’ relationship, whilst their findings may be subject to residual confounding. Future studies should consider potential differences of white rice varieties, which vary in amylose content, as well as the effect of processing methods.