Organic milk and meat contain 50% more beneficial omega-3 fatty acids than non-organic produce, a wide-ranging study has found.
An international group of scientists has also shown organic meat has slightly lower concentrations of two saturated fats which have been linked to an increased risk of heart disease.
The same team previously worked on a global study of organically produced crops which found they had up to 60% higher levels of antioxidants than conventionally grown fruit and vegetables.
Study leader Professor Carlo Leifert, of Newcastle University, said the research indicated that people could increase their omega-3 intake by choosing organic, or they could maintain their intake of the important fats but eat less meat if they switched.
"Nutritionists do not agree on many things, but they all say we should double our intake of omega-3," he said.
Western diets have been shown to lack these important fats, which are also found in oily fish and have been linked with reducing cardiovascular disease, improved neurological development and better immune function.
The study, published in the British Journal of Nutrition, reviewed 196 papers on milk and 67 on meat and found clear differences between organic and conventional products.
Key findings were in their fatty acid composition, and the concentrations of certain essential minerals and antioxidants.
Chris Seal, professor of food and human nutrition at Newcastle University, said: "Our study suggests that switching to organic would go some way towards improving intakes of these important nutrients."
The review found organic milk contained 40% conjugated linoleic acid, used as a weight loss supplement and by bodybuilders. It also had slightly higher concentrations of iron, Vitamin E and some carotenoids.
The differences between organic and conventional milk and meat was simply due to organically reared animals eating grass which contains the fats they require to develop, rather than concentrated cereal feeds, Prof Leifert said.
"People choose organic milk and meat for three main reasons: improved animal welfare, the positive impacts of organic farming on the environment, and the perceived health benefits," he said.
"But much less is known about impacts on nutritional quality, hence the need for this study.
"Several of these differences stem from organic livestock production and are brought about by differences in production intensity, with outdoor-reared, grass-fed animals producing milk and meat that is consistently higher in desirable fatty acids such as the omega-3s, and lower in fatty acids that can promote heart disease and other chronic diseases."
He said organic milk farmers had recently responded to findings about iodine by increasing its levels in their products.
The study also showed conventional milk contained 74% more of the essential mineral iodine and slightly more selenium.
Getting the right balance of iodine in the human diet is difficult, as the gap between deficiency and harmful excess is not wide, Prof Leifert said.
Both too little and too much iodine have been linked to thyroid problems. Unlike much of the rest of the world, table salt in the UK is not routinely fortified with iodine.
Cattle feeds also contain iodine, explaining the difference between organic and conventional meat.
Prof Leifert said: "Taken together, the three studies on crops, meat and milk suggest that a switch to organic fruit, vegetables, meat and dairy products would provide significantly higher amounts of dietary antioxidants and omega-3 fatty acids."