The extensive review of international research on the fruits shows reduction of risks of some cancers by up to 50 per cent and a 19 per cent decrease in risk of stroke.
Citrus fruit contain hundreds of nutrients including high levels of vitamin C and significant amounts of dietary fibre, beta-carotene and other antioxidants, and folic acid. They also have abundant phytochemicals, which are believed to have a role in preventing a range of chronic health conditions including cancer and heart disease.
The report, funded by Horticulture Australia, found 48 studies showing a protective effect of citrus fruits on cancers and additional studies showing links to vitamin C, carotenoids and folate or fibre intake. The greatest evidence is for oesophageal, larynx, mouth and stomach cancers where the reduction was between 40-50 per cent, it notes.
There is less evidence to back the fruit's relation to heart disease although some of it is highly significant. The WHO's recent draft report on 'Diet, Nutriton and the Prevention of Chronic Disease', which has brought into focus the role of diet in disease, concludes that there is convincing evidence that high intake of dietary fibre will protect against heart disease risk factors obesity and overweight.
Citrus fruits also have a low ratio of sodium to potassium, are low in fat, nutrient dense and energy-dilute and have a low glycaemic index.
Many of Australia's current health problems, like much of the developed world, are chronic diseases affected by diet, including coronary heart disease, obesity, type 2 diabetes asthma, osteoporosis and depression. According to the country's health secretary, Trish Worth, chronic diseases now contribute to 42 per cent of the burden of disease in Australia. More than 3 million Australians are obese and a further 5.6 million are overweight.
But the fruits have also been linked to protection against other diseases, thanks to their variety of compounds. An orange has over 170 different phytochemicals and more than 60 flavinoids, many of which have been shown not only to have antioxidant effects but also to have anti-inflammatory, anti-tumour and blood clot inhibiting properties.
The report also details possible health claims that could be used by industry to promote the health benefits. Some industry groups and companies are already communicating these through websites, also given in the report, but further efforts could help drive higher consumption of the fruits, based on their health benefits.
For more information on the report, contact the Australian Citrus Growers Association.