A review published online on 27 March 2026 in Nutrition Research argues that these fats do not harm the heart. The University of Reading announced it in May. ScienceDaily reposted the release on 7 October under the headline "Not All Trans Fats Are Bad". This article is written from the abstract and the publisher's record. The full text could not be opened from the newsroom.
The authors combined two kinds of evidence. The first is ten randomised controlled trials. Volunteers ate dairy products enriched with natural trans fats, obtained by changing the cows' diet, or ordinary dairy. Doses ran from 1.3 to 13.2 grams a day. The second is twelve cohort studies, which follow groups of people for years. Here researchers measured two fatty acids typical of milk, trans-vaccenic and trans-palmitoleic, in the blood, then counted heart attacks, strokes, cardiovascular deaths and cases of type 2 diabetes.
In the trials blood lipids did not change significantly, with one exception. HDL cholesterol, the so-called good kind, fell by 0.05 millimoles per litre, about 2 milligrams per decilitre. The confidence interval runs from minus 0.10 to zero. It is a small fall, at the margin. The abstract reports it. The press release speaks of no meaningful differences. In the cohorts, blood levels of the two fatty acids were not associated with more cardiovascular disease or more diabetes.

The authors conclude that at those doses dairy trans fats have no adverse cardiometabolic effects. The paper's title goes further. It says they "do not affect risk". The trials, though, measure blood lipids, not heart attacks. The cohorts measure an association. Those fatty acids in the blood mark people who eat more dairy, and that diet carries other habits an observational study cannot fully separate.
Then there are the signatures. The first and second authors, Constance Gayet-Boyer and Fanny Tenenhaus-Aziza, work for CNIEL, the French dairy industry's interbranch organisation. Moises Torres-Gonzalez works for the US National Dairy Council, the promotion body of American milk producers. Cindy Schweitzer is a private consultant. Ian Givens, of the University of Reading, is fourth author. ScienceDaily presents him as lead author.
Reading's original release stated that the research was funded by the National Dairy Council and that several authors work for or receive funding from industry bodies. In the publisher's metadata the registered funder is CNIEL. The version reposted by ScienceDaily carries neither line. The same French group published a similar review in the British Journal of Nutrition in 2014, also paid for by CNIEL, with thirteen trials. It too found no effect on the ratios of total to HDL cholesterol.

Funding does not make data false. It bears on the choices a review has to make, which studies to include and how to read them. No protocol registration was found in PROSPERO, the register where systematic reviews file their plans in advance. In July the journal published a correction to the article. Its content was not read.
The World Health Organization takes a different view. It regards industrial and natural trans fats as equally harmful. It recommends keeping all of them below 1 per cent of energy, about 2.2 grams a day on a 2,000-calorie diet. The top dose in the trials is six times that ceiling. The authors read this as a safety margin. For now the review has not changed the WHO recommendation.

Range of daily dairy trans-fat doses tested in the review's ten trials, compared with the WHO ceiling for all trans fats. Chart produced by ScienceOnline from data in Gayet-Boyer C. et al., Nutrition Research 2026, doi 10.1016/j.nutres.2026.03.009, and WHO.

References
Gayet-Boyer C., Tenenhaus-Aziza F., Torres-Gonzalez M., Givens D.I., Schweitzer C., "Trans fatty acids from dairy foods do not affect risk of cardiometabolic diseases: Systematic review and meta-analysis of evidence from randomized controlled trials and systematic review of prospective cohort studies", Nutrition Research, 150, 33–48, published online 27 March 2026, June 2026 issue, CC BY-NC-ND 4.0 licence. doi: 10.1016/j.nutres.2026.03.009
Corrigendum to the above article, Nutrition Research, 152, 171, August 2026 (content not read). doi: 10.1016/j.nutres.2026.06.004
Gayet-Boyer C., Tenenhaus-Aziza F., Prunet C., Marmonier C., Malpuech-Brugère C., Lamarche B., Chardigny J.M., "Is there a linear relationship between the dose of ruminant trans-fatty acids and cardiovascular risk markers in healthy subjects: results from a systematic review and meta-regression of randomised clinical trials", British Journal of Nutrition, 112, 12, 1914–1922, 2014, CC BY 3.0 licence. doi: 10.1017/S0007114514002578
World Health Organization, fact sheet "Trans fat", accessed 9 October 2026.
University of Reading, press release "Natural trans fats in dairy do not raise heart disease risk", 26 May 2026; reposted by ScienceDaily on 7 October 2026 (used only as a lead).

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Past Editor-in-Chief Italian Journal of Dermosurgery