Review of 22 Studies Finds Dairy’s Natural Trans Fats Didn’t Raise Heart Risk

Leave a CommentReview of 22 Studies Finds Dairy’s Natural Trans Fats Didn’t Raise Heart RiskFood, Nutrition

For decades, “trans fat” has been one of the scariest phrases on a food label. But a new review argues that lumping all trans fats together is a mistake, and that the small amount found naturally in milk, cheese and other dairy foods doesn’t behave like the factory-made kind.

“People hear the words ‘trans fats’ and assume the worst,” said Professor Ian Givens of the University of Reading in England, a lead author of the review.

What the review looked at

The paper, published in the journal Nutrition Research, is a systematic review and meta-analysis. That means the authors gathered and analyzed earlier studies instead of running a single new experiment. They pooled 22 studies involving thousands of people in Europe, Canada and the United States, according to the University of Reading.

The 22 studies fell into two groups:

  • 10 controlled diet trials. Volunteers ate either dairy with naturally boosted trans fat levels or regular dairy. Trans fat intakes ranged from 1.3 to 13.2 grams a day. The researchers found no meaningful differences in blood fats such as cholesterol between the groups.
  • 12 long-term cohort studies. These followed people over time, some for more than two decades, and measured dairy trans fats in their blood. Higher levels were not linked to a greater risk of heart disease, stroke or death from cardiovascular disease. They also weren’t linked to type 2 diabetes.

“Dairy, eaten as part of a balanced diet, is not something to worry about for your heart,” Givens said, according to ScienceDaily.

Two very different kinds of trans fat

Here’s the distinction that matters.

Industrial trans fats came from partially hydrogenated oils, or PHOs, a factory process once common in processed foods. They are strongly linked to heart disease, according to the University of Reading and ScienceDaily.

Natural trans fats occur in small amounts in meat and dairy products, the FDA says. According to the University of Reading, the natural forms found in dairy “appear to pose no risk,” unlike industrial trans fats.

The government has already dealt with the industrial kind. In 2015, the FDA ruled that PHOs are not “generally recognized as safe.” Manufacturers could no longer add them to foods made after June 18, 2018, with the last exceptions phased out by 2021, according to the FDA. The agency said removing PHOs “could prevent thousands of heart attacks and deaths each year.”

The FDA also noted that trans fat won’t disappear from food entirely, because small amounts occur naturally in meat and dairy. That’s the trans fat this review studied.

One thing to know about the funding

The University of Reading disclosed that the review was funded by the National Dairy Council in the United States, and that several authors work for or receive funding from dairy industry organizations. That doesn’t make the findings wrong, but it’s worth knowing, and it’s one reason a single review shouldn’t be the last word.

The review also can’t prove cause and effect from the long-term cohort studies. Those show patterns in large groups, not what happens inside any one person.

What this means at the grocery store

You don’t need to overhaul your diet based on one paper. But a few practical takeaways hold up:

  • The trans fat to avoid is the industrial kind. Thanks to the FDA ban, PHOs have been out of new U.S. foods since 2018. If you still have very old packaged goods in the back of the pantry, check the ingredient list for “partially hydrogenated oil.”
  • Dairy’s natural trans fat isn’t the same thing. By this review’s findings, it isn’t a reason to give up milk, cheese or yogurt.
  • Balance still matters. The researchers framed their conclusion around dairy “eaten as part of a balanced diet,” not unlimited amounts.
  • Talk to your doctor if you have heart disease or high cholesterol and have been told to limit certain fats.

The bottom line

Nutrition advice has a habit of painting whole food groups with one brush. This review is a reminder to look closer. The trans fat that caused real harm came from a factory process, and it’s already off the shelves. The small amount that occurs naturally in dairy is a different thing, and in these 22 studies it didn’t show the same danger.

For families who keep a few dairy cows or goats, buy local milk or simply like real cheese, that’s welcome news.

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