In the largest study of its kind an international
team of experts at Newcastle University, UK, have
shown that both organic milk and meat contain around
50% more beneficial omega-3 fatty acids than
conventionally produced products.

Gillian Butler, Senior Lecturer in animal nutrition
at Newcastle University
Analysing data from around the world, the team led
by Newcastle University, reviewed 196 papers on milk
and 67 papers on meat and found clear differences
between organic and conventional milk and meat,
especially in terms of fatty acid composition, and
the concentrations of certain essential minerals and
antioxidants.
The systematic literature reviews analysed data from
around the world and found that organic milk and
meat have more desirable fat profiles than
conventional milk and meat.
Most importantly, a switch from conventional to
organic would raise omega-3 fat intake without
increasing calories and undesirable saturated fat.
For example, half a litre of organic full fat milk
(or equivalent fat intakes from other dairy products
like butter and cheese) provides an estimated 16%
(39 mg) of the recommended, daily intake of very
long-chain omega-3, while conventional milk provides
11% (25 mg).
Other positive changes in fat profiles included
lower levels of myristic and palmitic acid in
organic meat and a lower omega-6/omega-3 ratio in
organic milk.
Higher levels of fat soluble vitamins such as
vitamin E and carotenoids and 40% more CLA in
organic milk were also observed.
The study showed that the more desirable fat
profiles in organic milk were closely linked to
outdoor grazing and low concentrate feeding in dairy
diets, as prescribed by organic farming standards.
Chris Seal, Professor of Food and Human Nutrition at
Newcastle University explains: “Omega-3s are linked
to reductions in cardiovascular disease, improved
neurological development and function, and better
immune function.
Gillian Butler, co-author and senior lecturer in
animal nutrition at Newcastle University, explains:
“There is a relatively narrow margin between dietary
Iodine deficiency (<140 µg/day) and excessive
intakes (> 500 µg/day) from our diet which can lead
to thyrotoxicoxis(…) “Optimising iodine intake is
therefore challenging, since globally there seems to
be as much concern about excessive rather than
inadequate intake.”
The daily recommended intake of iodine in the UK is
140 µg/day and just over half comes from dietary
sources other than milk/dairy products. Based on
results from the study, half a litre of milk would
provide 53% of and 88% of the daily recommended
intake from organic and conventional milk
respectively. However, pregnant and breastfeeding
women have a higher iodine requirement (250 µg/day)
and are therefore more at risk of iodine deficiency,
which could affect neurological development in
babies.
In the USA, China, Brazil and many European
countries, where Iodine fortified salt is widely
used, elevated levels of iodine in milk may increase
the risk of excessive intake for individuals with
high dairy consumption. For this reason the European
Food Safety Authority (EFSA) has proposed a
reduction in the permitted level of iodine in cattle
feed from 5 to 2 mg iodine per kg of feed.
Newcastle University’s Professor Carlo Leifert, who
led the studies, 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.
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.”
The work builds on a previous study by the team –
involving experts from the UK, US, France, Italy,
Switzerland,and Poland – investigating the
composition of organic and conventionally-grown
crops.
This previous study – also published in the British
Journal of Nutrition – showed that organic crops and
crop-based foods are up to 60% higher in a number of
key antioxidants than conventionally-grown crops and
contained less of the toxic metal cadmium.
“We have shown without doubt there are composition
differences between organic and conventional food.
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,” concludes Professor
Leifert.
“We need substantially more, well designed studies
and surveys before we can accurately estimate
composition differences in meat from different farm
animals and for many nutritionally important
compounds (vitamins, minerals, toxic metal and
pesticide residues), as there is currently too
little data to make comparisons.
“However, the fact that there are now several mother
and child cohort studies linking organic food
consumption to positive health impacts shows why it
is important to further investigate the impact of
the way we produce our food on human health.
For more information
Read the Open Access papers in full:
British Journal of Nutrition
Higher PUFA and n-3 PUFA, conjugated linoleic acid,
a-tocopherol and iron, but lower iodine and selenium
concentrations in organic milk: a systematic
literature review and meta- and redundancy analyses.
Dominika Srednicka-Tober et al.
Link...
Composition differences between organic and
conventional meat:
a systematic literature review and meta-analysis
Link...
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