Cereal grains and their products provide around 30% of total energy intake in British adults, (much more than any of the other major food groups). Coronary heart disease (CHD) is the largest single cause of death in Britain and many other Western countries. This review examines the question whether there is a relation between cereal consumption and CHD.Several of the nutrients in cereals have known potential for reducing risk factors for CHD: the linoleic acid, fibre, vitamin E, selenium and folate. Cereals also contain phytoestrogens of the lignan family and several phenolic acids with antioxidant properties. Processing generally reduces the content of these nutrients and bioprotective substances. Although cereals at the farm gate are very low in salt, processed cereal foods, eg bread and some breakfast cereals, are high-salt foods and thus could contribute to raising blood pressure.Human experiments have clearly shown that oat fibre tends to lower plasma total and LDL cholesterol but wheat fibre does not. Rice bran and barley may also lower cholesterol but most people do not eat enough barley to have an effect. Cereal foods with low glycaemic index such as pasta and oats are beneficial for people with diabetes and might lower plasma lipids.Between 1996 and 2001 an accumulation of five very large cohort studies in the USA, Finland and Norway have all reported that subjects consuming relatively large amounts of whole grain cereals have significantly lower rates of CHD. This confirms an earlier report from a small British cohort. The protective effect does not seem to be due to cholesterol-lowering. While cohort studies have shown this consistent protective effect of whole grain cereals, there has been (only one) randomised controlled secondary prevention trial of advice to eat more cereal fibre. In this there was no reduction of the rate of reinfarction. The trial had some weaknesses, eg there were eight different diets, compliance was not checked objectively, and duration was for only 2 y.It appears valid to make health claims (as now permitted by the US FDA) that whole grain cereal foods and oat meal or bran may reduce the risk of CHD.

A low-GI diet gives a modest improvement in long-term glycemic control but not plasma lipids in normolipidemic well-controlled subjects with NIDDM.

Small-intestinal absorption of fructose was investigated in healthy human subjects by sequential breath-hydrogen measurements. Fifty-eight percent of 103 subjects produced greater than 20 microL H2/L after consuming 50 g pure fructose in water. About half of those who absorbed fructose incompletely (incomplete absorbers) had abdominal symptoms. Malabsorption of medium doses of pure fructose may therefore be common in man. When 25 g pure fructose was consumed, only 19% of 21 poor absorbers (of 50 g fructose) still produced excess breath H2. When glucose was taken with fructose, the frequency and amount of excessive breath H2 was substantially reduced. This facilitating phenomenon is not generally known but is important because in natural foods fructose occurs in association or in combination (as sucrose) with glucose. Plasma fructose responses were not lower in poor absorbers presumably because these responses depend more on how much fructose passes through the liver than on how much is absorbed.

The purpose of the study was to compare the in vitro starch digestibility and postprandial blood glucose response of conventionally-cooked versus factory-processed foods. Carbohydrate portions of three unprocessed foods (boiled rice, sweet corn, and potato) and six processed foods (instant rice, Rice Bubbles, corn chips, Cornflakes, instant potato, and potato crisps) were incubated for 3 h with human saliva and porcine pancreatin. The proportion of starch digested was significantly higher (p less than 0.05) for the processed forms of rice, corn, and potato compared with the respective conventionally cooked foods. In six healthy volunteers who ingested 50 g carbohydrate portions of the above foods the processed foods produced a higher glycemic index (p less than 0.05) in all but one instance. The exception was potato crisps which gave a similar glycemic response to boiled potato.