Two recent studies, in the UK and US, have stirred up debate over whether organic food really is more nutritious reports Organic Aotearoa NZ in its July 2007 newsletter.
The latest study, by the British Nutrition Foundation and published in the journal Nutrition Bulletin, concludes, "From a nutritional perspective, there is currently not enough evidence to recommend organic foods over conventionally produced foods."
The study adds, however, there are good reasons to choose organic food because it represents a sustainable method of agriculture that avoids the use of artificial fertilisers and pesticides and makes use of crop rotation and good animal husbandry to control pests and diseases.
But this finding is contradicted by another recent study, by the University of California, which found organic fruit and vegetables may be better for the heart and general health than crops grown conventionally.
Higher Antioxidants in organic tomatoes
This is due to the higher anti-oxidant levels of organic produce. The 10-year study compared organic and non-organic tomatoes, and found the organic ones have almost twice the quantity of antioxidants (called flavonoids) that help to prevent high blood pressure, thus reducing the likelihood of heart disease and strokes.
There have been other studies, too. In March, a European Union research programme reached similar conclusions about organic peaches, apples and tomatoes. In the case of all three fruits, there were higher levels of vitamin C and of flavonoids, as well as polyphenols, which can protect against cancer.
So advocates of organic food will not be too worried by the latest British Nutrition Foundation report, which concludes, "Much more research is still needed, particularly to determine whether there are any nutritional differences between organic and non-organic fish, meat and other animal products."
Organic Potatoes higher in Vitamin C
But even this somewhat sceptical report was tempered by the acknowledgement there may be nutritional benefits in organic potatoes, which were found to be richer sources of vitamin C than their conventionally grown counterparts.
And for organic milk, the British study found higher levels of alpha-linolenic acid, conjugated linoleic acid, alpha-tocopherol (vitamin E), beta-carotene, and a higher proportion of polyunsaturated fatty acids to monounsaturated fatty acids.
The report concludes, despite "insufficient data", nutrition is not the main reason why people choose organic food. Concerns about the environment, pesticide levels, food additives or animal welfare are listed as more important factors by many consumers.