Trans-Fatty Acids in Milk and Dairy Products






“Milk fat contains 2-4% trans-fatty acids.” This statement is found in a conventional food chemistry textbook. Trans-fats? Yes, precisely! Those fats for which a legal limit was set in some countries due to their harmfulness.

The fact that animal foods contain large proportions of saturated fatty acids, which are not exactly health-promoting, should be well-known. In the case of milk, a good two thirds of the fats are saturated fatty acids. But that’s not all; they also contain trans-fatty acids. According to the textbook cited above, 2-4% of milk fats (1). And what’s more: “dairy products contain 3-6% trans-fatty acids,” as stated in presentation by the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management (2). These trans-fats are produced in the stomach of ruminants (rumen) and then come into the milk along with other fats. In this publication we also find the subtle evidence that these percentages do not quantify the total amount, only one representative of trans fatty acids (elaidic acid) was measured.

The effects of trans-fatty acids in the human body

Why are trans fatty acids so worrisome? It is known that they increase cholesterol – and above all the “bad” cholesterol – thus leading to an increased cardiovascular risk (3). Cancer risk is also expected to be increased (4). While the EU has not managed to limit trans-fatty acids, certain countries, notably Denmark and Austria, have created arrangements to protect against the effects of trans-fatty acids. In Austria, this is the so-called trans-fatty acid regulation (5), which came into force with October 2009. Under this Regulation, products containing more than 20% fat must not contain more than 2% trans-fatty acids of total fat content. For products below 20% fat, the trans fat content must not exceed 4%. It should be noted that cream and cheese contain far more than 20% fat and therefore exceed these limits. But in the trans-fatty acid regulation, food from animal sources are expressly excluded. In the text, the following is stated: “§1 (3) This Regulation shall not apply to trans-fatty acids derived from fats of animal origin …” (5).

Why is there so little fuss about it? Are animal-derived trans fats less harmful? Many authors seem to want to make this believable. Two arguments are brought into play: one states that milk also contains conjugated linolenic acid (CLA), a fatty acid which is said to have health promoting effects (1), more on this later on. The second argument is that these “ruminant” trans fats (produced in ruminants) are harmless since they can be converted into the “good” CLA in the human body (6). It is to be said that this transformation is hypothetical and it is by no means clear when this happens, and to what extent. We only know that this transformation is theoretically possible.

CLA – a healthy trans-fatty acid?

And now, to the alleged health-promoting effects of the CLA. So far, many producers have tried to sell CLA preparations under health aspects such as: promoting weight reduction in overweight people, building muscle mass, protecting the DNA from damage and improving the immune system. An attempt was made to market the substance especially as a weight-loss product. In its Health Claims (EC) No 1924/2006 (7), the European Food Safety Authority (EFSA) has rejected all applications alleging a health benefit, on the basis of insufficient evidence. Thus it is not only unclear how far the trans-fatty acids are actually “neutralised” in dairy products. Even if this is actually the case for CLA, we have no factual evidence to back its alleged benefits.

CLA and cancer?

But how about the assertion that CLA protects against cancer; is there some truth to it? In a large-scale meta-analysis breast cancer risk was not associated with CLA doses, nor serum CLA levels (8). On the contrary, one study showed an increased risk of breast cancer (9).

Finally, it should be mentioned that trans-fats and CLA are not present in vegetable derived, unprocessed fats (10). These health claims and arguments for trans-fatty acids and CLA thus seem to be merely a diversion.

Here are inquiries I have written to several institutions:

Questions to the Austrian Federal Ministry for Women and Health (BMFG)

  1.   You write about the problems associated with trans-fatty acids (11) on your website. In this context, you refer expressly and exclusively to “artificial”, ie industrially produced trans fats. Is there a proven difference between industrial and “ruminant” or “natural” trans fats? And if not, why exclude the latter?
  2. Why do you make the version of August 2009 regulation available on the same website (12), but not the current version of the regulation?
  3. The currently valid regulation presumably has eliminated the products with the absolute peak values ​​of trans fats from our food chain and have thus been a very important step towards protecting the consumer. But the amounts of trans-fatty acids in milk and dairy products are not insignificant. What is planned to protect Austrians from trans-fatty acids in milk and dairy products? What is the specific situation with measures such as deletion of the derogation rules for trans fats of animal origin or with an obligation to label trans-fats?

Questions to the Austrian Agency for Health and Nutrition Safety (AGES)

  1.  On your website (13) there is a reference to “natural” trans-fats, but no reason is given for them to be excluded from the regulation.
  2.  You also point to the existing European regulations concerning infant formulas and olive oil. If trans-fatty acids can also occur in olive oil and are even limited in the much less restrictive European regulation, is this a further indication that “natural” trans fats are by no means less harmful than industrially produced ones?
  3.  Why is elaidic acid measured when the amount of trans-fatty acids is determined, considering that the proportion of vaccic acid is not insignificant?

Questions to Agrarmarkt Austria Marketing GesmbH (AMA)

  1.  You list on your website the various components of milk (14). Why are only the short-chain fatty acids listed, but not the unsaturated fatty acids, and not the trans-fatty acids?
  2.  There is a very long list of quality criteria in your directive on the AMA seal of approval (15). From the receipt of the goods, the precise regulations concerning the packaging up to the control of the control. Why is the trans-fatty acid content not among the control criteria in quality control?
  3.  In your campaigns, you are always applying milk, cheese, eggs and meat. Why do you not provide information about herbal products as well? About local vegetable and bean varieties, domestic cereals and fruit varieties etc.?
  4.  Why does your website look like a meat store? Under the heading “Recipes” there is not a single vegan recipe. Not even a single salad without cheese or bacon! And what is to be found under “product diversity” is obviously a successful caricature! The best way to show it with a screenshot! I thought there were some vegetable growers, grain growers and maybe a few different vegetable varieties in Austria?


Myself and the readers of my website would greatly appreciate informative answers.


Add on, 19.3.2019:

AMA has replied (see comment in the german version).

In the US, too, this is clearly an issue. As Dr. Greger reports in his Nutrition blog (16), the main sources of trans fats in industrially produced fats are actually milk, dairy products and meat. There is a report that recommends limiting trans fat consumption as much as possible. Nevertheless, the head of the cardiovascular epidemiology program at Harvard, Dr. Eric Rimm (17), can not go through to recommend a vegan diet. He says: “We might be able to recommend a vegetarian diet (comm.: Ah, yes? The report deals with milk and dairy products!?) but that would be a little extreme!”


Photo: various types of cheese,

(1) Robert Ebermann, Ibrahim Elmadfa: Lehrbuch Lebensmittelchemie und Ernährung. Zweite, korrigierte und erweiterte Auflage, 2011, SpringerWienNewYork. Seite 321
(2) to publikation of Ministery of Agriculture
(3) Brouwer IA, Wanders AJ, Katan MB. Effect of animal and industrial trans fatty acids on HDL and LDL cholesterol levels in humans–a quantitative review. PLoS One. 2010 Mar 2;5(3):e9434.
(4) Laake I, Carlsen MH, Pedersen JI, Weiderpass E, Selmer R, Kirkhus B, Thune I, Veierød MB. Intake of trans fatty acids from partially hydrogenated vegetable and fish oils and ruminant fat in relation to cancer risk. Int J Cancer. 2013 Mar 15;132(6):1389-403.
(5) to Austrian Trans-Fatty acids-Regulation
(7) EFSA report on “Health Claims” regarding CLA
(8) Arab A, Akbarian SA, Ghiyasvand R, Miraghajani M. The effects of conjugated linoleic acids on breast cancer: A systematic review. Adv Biomed Res. 2016 Jul 6;5:115. doi: 10.4103/2277-9175.185573.
(9) Voorrips LE, Brants HA, Kardinaal AF, Hiddink GJ, van den Brandt PA, Goldbohm RA. Intake of conjugated linoleic acid, fat, and other fatty acids in relation to postmenopausal breast cancer: the Netherlands Cohort Study on Diet and Cancer. Am J Clin Nutr. 2002 Oct;76(4):873-82.
(10) Kuhnt K, Baehr M, Rohrer C, Jahreis G. Trans fatty acid isomers and the trans-9/trans-11 index in fat containing foods. Eur J Lipid Sci Technol. 2011 Oct;113(10):1281-1292.
(11) to website of BMFG
(12) to old version of Trans-Fatty acids-Regulation
(13) to website of AGES GmbH
(14) to AMA-website on milk
(15) to AMA guideline for qualitiy seal for milk and dairy products
(16) to Dr. Gregers blog

(17) Direktor Cardiovascular Epidemiologic Program

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