Butter, Margarine, and 60 Years of Confusion

Good morning!

Few nutrition debates have flip-flopped as dramatically as butter versus margarine. Butter was demonized for decades, margarine was sold as the healthy alternative, then margarine became the villain, and now butter is having a cultural comeback while scientists are quietly pointing back at the data.

If you've lost track of where things actually stand, you're not alone, the story has genuinely changed multiple times, and not always for the right reasons. This week, we're looking at what the research actually says about both.

Key Takeaways

• Margarine was recommended over butter for decades, but the process used to make it solid created industrial trans fats that raised bad cholesterol while simultaneously lowering good cholesterol.

• The FDA banned partially hydrogenated oils from U.S. food products in 2018, and a study confirmed that modern margarines now contain substantially less saturated fat than butter and no man-made trans fats at all.

• Liquid plant oils such as olive and canola have the strongest evidence for supporting cardiovascular health.

CORE

What's actually in each

Let’s start with the basics.

Butter is mostly fat… shocker, I know. About half is saturated fat, a fourth is monounsaturated, and roughly 4% is polyunsaturated. It contains cholesterol, vitamin A, vitamin E, and vitamin K2, particularly in grass-fed versions. 

Margarine takes a different approach. It's made from plant oils, so its fat profile is almost the reverse: roughly half monounsaturated fat, about a third polyunsaturated fat, and substantially less saturated fat, around 15-20 grams per 100 grams compared to butter's 51 grams. Generally speaking, the firmer the margarine, the more saturated fat it contains. Soft tub margarines usually have less than stick versions.

Both butter and margarine provide vitamins A and E, although margarine is often fortified with extra vitamin E and vitamin K. Vitamin E acts as an antioxidant, helping protect your cells from everyday wear and tear, while vitamin K plays an important role in normal blood clotting.

Butter, meanwhile, contains vitamin K2, a form of vitamin K found almost exclusively in animal and fermented foods. K2 helps direct calcium toward your bones and teeth instead of allowing it to accumulate where it shouldn't, such as in blood vessels. Butter also contains small amounts of butyrate, a fatty acid that serves as fuel for the cells lining your colon and may support gut health, along with conjugated linoleic acid (CLA), another naturally occurring fat that has been studied for potential effects on metabolism and inflammation. That said, the amounts found in a typical pat of butter are fairly small, so they're better viewed as a nice bonus than a major health benefit.

The misconception that defined a generation

From the 1960s through the 1980s, margarine was actively recommended by physicians as the heart-healthy alternative to butter. The reasoning seemed perfectly logical at the time: butter is high in saturated fat and cholesterol, while margarine is made from plant oils and contains far less of both.

The problem was the process required to make liquid vegetable oil solid (partial hydrogenation) which added hydrogen to the oil to give it structure and shelf life.

The problem? Making liquid vegetable oil behave like butter wasn't exactly easy. Manufacturers relied on a process called partial hydrogenation, which added hydrogen to liquid oils to make them solid and shelf-stable. Unfortunately, it also created industrial trans fats, something nobody realized was a problem until years later.

In the early 1990s, studies began revealing that industrial trans fats, created as a byproduct of partial hydrogenation, increased the risk of coronary heart disease.

The effect was a double hit. Industrial trans fats not only raised levels of LDL, the so-called "bad" cholesterol, but also decreased levels of HDL, the "good" cholesterol. A combination that made them arguably worse for cardiovascular health than the saturated fat in butter they were supposed to replace.

A landmark 1993 review published in Epidemiology examined all the available research and found that every study reported a link between industrial trans fats and a higher risk of heart disease.

The healthy alternative wasn't so healthy after all.

Why modern margarine is a different product

In 2015, the FDA determined that partially hydrogenated oils were no longer generally recognized as safe, leading to a full ban that took effect in 2018. Food manufacturers had to reformulate entirely. A University of Minnesota School of Public Health study then compared the nutritional composition of margarines before and after the ban, and found that margarine and butter-blend products now contain substantially less saturated fat and cholesterol compared to butter, and contain no man-made trans fat.

The margarine people are avoiding in 2025, because they heard it was full of trans fats, is not the same product that earned that reputation. The trans fat era of margarine is over. Modern margarine isn't perfect, but it's a very different product.

The honest nuance

Butter does raise LDL cholesterol, but it also raises HDL cholesterol. Whether that tradeoff translates into worse long-term health depends on the rest of your diet, your lifestyle, and the question researchers are asking. Large observational studies consistently associate higher butter intake with greater mortality, but they can't prove butter itself is entirely responsible. People who eat more butter may also differ in dozens of other ways, from exercise habits to overall diet, that are difficult to fully account for.

Butter also contains nutrients that don't get much attention in social media debates. Vitamin K2 may support bone and cardiovascular health, butyrate may benefit gut cells, and CLA has shown interesting effects in laboratory and animal studies. None of these suddenly transform butter into a superfood, but they do remind us that foods are more than just one nutrient on a label.

The strongest evidence still points in the same direction: replacing saturated fat with unsaturated fat, especially from liquid oils like olive, canola, and soybean oil, helps lower LDL cholesterol and likely reduces the risk of cardiovascular disease over time.

That doesn't necessarily mean replacing butter with margarine specifically. It simply means that, if you're choosing a fat for everyday use, liquid plant oils have the best evidence behind them.

So which should you use?

For everyday cooking, salad dressings, and most recipes, liquid plant oils, particularly olive and canola oil, have the strongest evidence supporting their long-term health benefits.

If you're baking cookies or finishing a steak, butter is perfectly reasonable in moderation. Life is too short for sad toast.

If you're looking for a spread, modern soft tub margarines made primarily from plant oils are much closer nutritionally to those healthier oils than they are to the trans fat-laden margarines of the 1980s, making them a reasonable choice if you're trying to cut back on saturated fat.

What today's evidence doesn't support is either extreme you'll find online: that butter is a super food, or that margarine is somehow toxic. As with most nutrition debates, the truth is considerably less exciting, and considerably more useful.

ENDNOTE

Final Thoughts

And of course, even as a dietitian I’ll say: if butter speaks to your soul, there's little evidence that enjoying it in moderation as part of an otherwise balanced diet will do you any harm. There are far worse life choices than a pat of butter.

Until next week!

Adrian Macdonald | Team Dietitian | The 8% Newsletter Author