Researchers have found that organic milk generally contained less saturated fat and more good fatty acids than milk produced at intensive commercial dairy farms.
Its health giving properties were also much less likely to be affected by changes in the weather.
Scientists at the University of Newcastle found non-organic milk collected during a particularly poor UK summer and the following winter had significantly higher saturated fat content and far less beneficial fatty acids than in a more "normal" year.
But they also discovered that switching to organic milk could help overcome these problems.
Organic supermarket milk showed higher levels of nutritionally beneficial fatty acids compared with "ordinary" milk regardless of the time of year or weather conditions.
Gillian Butler, who led the study, puts the differences down to a lower reliance on grazing and fertiliser suppressing clover on conventional farms.
"The results suggest greater uniformity of feeding practice on farms supplying organic milk since there were no brands which differed consistently in fat composition," she said.
"This implies a fairly uniform approach to feeding practised across these suppliers."
Organic dairying standards prescribe a reliance on forage, especially grazing, and, in the absence of nitrogen fertiliser, tend to encourage swards of red and white clover, which have been shown to alter the fatty acid intake and composition of milk.
While protein, antioxidants, vitamins, minerals and some mono and polyunsaturated fatty acids in milk are considered beneficial, saturated fatty acids are believed to have a negative effect on human health.
"We're always being told to cut down on the saturated fat we consume and switching to organic milk and dairy products provides a natural way to increase our intake of nutritionally desirable fatty acids, vitamins and antioxidants without increasing our intake of less desirable fatty acids," said Mrs Butler.
"By choosing organic milk you can cut saturated fats by 30-50 per cent and still get the same intake of beneficial fatty acids, as the omega-3 levels are higher but omega-6 is not, which helps to improve the crucial ratio between the two."
While undertaking their research into the differences between organic and conventional milk, the researchers discovered the surprising link between milk quality and our changing climate.
Their results suggest that if we continue to have wetter, cooler summers then farmers may have to rethink their current dairy practices.
There was a considerable difference between the milk bought in the first sampling period (July 2006 and January 2007) and corresponding times a year later.
The second set of samples, following a particularly wet summer in 2007, was higher in saturated fat and lower in beneficial fatty acids.
The researchers, who are part of the University's Nafferton Ecological Farming Group and its Human Nutrition Centre, looked at the quality of 88 different milks in supermarkets across North East England at varying times of year over a two-year period.
They concluded that organic brands of milk available in supermarkets are higher in beneficial fatty acids and omega-3 fatty acids in summer and winter.
Emma Hockridge, head of policy at the Soil Association, said: "This groundbreaking research proves for the first time that people buying organic milk will be benefiting from the higher levels of beneficial fatty acids in organic milk through the whole year."
The study was published in the Journal of Dairy Science.