03 August 2002
Wholegrain cereals such as brown rice, wholegrain wheat, whole oats and rye, not only taste great - they also offer potential health benefits including reduced risk of heart disease and certain cancers.
Recent large-scale epidemiological studies have shown that regular consumption of wholegrain cereals can reduce the risk of coronary heart disease (CHD) and certain cancers by up to 30 per cent. It comes as no surprise then that an international symposium on wholegrains and health in Finland in June 2001, concluded that eating more wholegrain foods could help improve health.
For centuries, cereal grains like wheat, rice, maize, oats and rye have been the mainstay of the diet. From pasta in Italy to porridge in Scotland, the variety of grain products eaten throughout the world is nothing short of amazing. Yet the majority of grain foods are eaten in refined form. This means that the outer parts of the grain-the germ and the bran- have been removed by milling, leaving the starchy endosperm, which is ground to produce white flours.
Milling and refining result in significant losses of nutrients and other protective substances that are present in the highest amounts in the germ and bran. Nutrients found in wholegrains include vitamin E, the vitamin B complex, and minerals such as selenium, zinc, copper, iron, magnesium and phosphorus. In addition to these vitamins and minerals wholegrains contain protein, complex carbohydrates and protective substances such as lignans (plant phytoestrogens with reported health-promoting properties against heart disease and cancer). All of these nutrients appear to work together as a "package" to help promote health and protect against disease.
Protection against cancer and heart disease
The real power of wholegrains, however, lies in their potentially protective effects against coronary heart disease (CHD) and certain cancers. In a prospective study of over 34,000 women aged 55-69 years in Iowa, USA, subjects who reported eating at least one serving of wholegrain cereals per day had a substantially lower risk of dying from CHD than those who ate almost none. Further data from the Nurses' Health Study showed that those women who ate about 2.7 servings of wholegrain foods a day had a 30% decreased risk of CHD compared with those eating only 0.13 servings per day. Moreover, regular consumption of wholegrain foods also appears to lower risk of stroke and type 2 diabetes.
The protective effects of wholegrain extend to cancers, especially colon cancer. Wholegrains are rich sources of fermentable carbohydrates, which are transformed by the intestinal flora into short-chain fatty acids. These acids can reduce the activity of certain cancer-causing factors. Wholegrain fibres also increase faecal bulk and bind carcinogens, which can be speedily removed from the bowel before they cause problems.
A note of caution : Phytates and health
While wholegrain cereals appear to offer many health benefits, very high intakes of wholegrains, especially in the uncooked or raw form, such as unprocessed bran, are not advisable. This is because the fibre, usually removed by milling, contains substances called phytates. Phytates have been shown to reduce the body's absorption and utilisation of several minerals including calcium and zinc. The enzymes in yeast (used for baking bread) destroy most of the phytates, as do food-processing methods that require heat, such as the processing of bran breakfast cereals. For most people the amount of phytates in the diet poses no problem however those with extremely high intakes of wholegrain cereals, may require a mineral supplement.
In the United States, the Food and Drug Administration (FDA) has authorised a health claim that recognises the importance of wholegrain foods and other plant foods in reducing the risk of CHD and some cancers. The health claim can be included on wholegrain food packaging and in advertising for these foods. In addition the FDA permits specific health claims for oats and oats products.
Wholegrain cereal foods, such as breads, wholegrain breakfast cereals, brown rice and crackers, are in short supply in the diets of most Western countries. An increased intake of these foods would be an attractive and prudent food-based strategy targeted at the whole population. Better health and reduced risk of certain diseases may be as simple as eating a bowl of wholegrain breakfast cereal and switching to wholegrain bread, rice and pasta.
VTT Symposium on Wholegrain and human health (2001) Proceedings of the International Symposium, Finland, June 13-15, 2001. Technical Research Centre of Finland (VTT), pp. 1-145