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What exactly are trans fats?
Typically, we talk about two major groups of dietary fats – unsaturated and saturated.
Unsaturated fats are liquid at room temperature. Saturated fats are solid at room temperature. It’s the saturated fats that are associated with health concerns as they can raise LDL (aka “bad”) cholesterol and increase inflammation.
Trans fats are technically unsaturated fats. But a slight difference in their molecular arrangement means they act more like saturated fats – in foods and the body.
Which foods have trans fats?
Small amounts of trans fats occur naturally in some animal foods, such as red meat and dairy. They can also be created when oils are heated to very high temperatures, such as with commercial deep-frying.
But most trans fats in our diets are “industrial” trans fats. These are made when unsaturated fats are deliberately turned into trans fats by a process called hydrogenation . This makes them act more like saturated fats – improving shelf life, taste and texture.
Industrial trans fats can be ingredients in pre-packaged foods such as shelf-stable cakes, pastries, fried savoury snacks and some frozen foods.
Why should we be cutting down on trans fats?
Initially, industrial trans fats were regarded as an innovation as they allowed manufacturers to replace expensive, unhealthy saturated fats.
But we now know trans fats don’t just act like saturated fats in foods. They also act like saturated fats in the body , raising LDL cholesterol and causing inflammation. This ultimately increases the risk of cardiovascular diseases (such as heart attacks and strokes) even if you don’t eat much of them.
The World Health Organization (WHO) recommends we keep trans fats to less than 1% of our total energy intake (which is about 2.2 grams per day if you are eating a standard 8,000 kilojoule diet). That means eating less than about four 300g serves of frozen lasagne a day.
The use of trans fats in Australia has declined in recent decades and the average consumption of trans fats is below the WHO-recommended levels. But an estimated 10% or so of Australians are eating more than the WHO recommends.
Some countries have introduced regulations to limit the levels of trans fats allowed in foods. The WHO recommends foods contain no more than 2g of trans fats per 100g of total fats. This hasn’t happened in Australia despite some calls for it .
Because “industrial” trans fats are typically found in prepackaged discretionary foods (such as shelf-stable pastries, cakes and biscuits) and convenience foods (such as frozen meals), it’s tempting to revert to the simplified “just eat fresh whole foods and cook from scratch” style of recommendation.
But cooking from scratch may not be realistic
However, for many people, cooking every meal from scratch isn’t practical, affordable or enjoyable. But there are practical and meaningful ways to eat less trans fats even when eating convenience and discretionary foods, without changing your whole lifestyle or becoming a chef.
When shopping for snacks, frozen or other pre-packaged convenience products, check the labels for trans fats. But this can be a bit tricky as they’re not always mentioned, or may be called something else.
In Australia, it’s not mandatory to include trans fats on food labels, unless a manufacturer makes nutrition or health claim about fats or cholesterol . If this is the case, trans fat needs to be listed on the nutrition information panel.
The rest of the time, the trans fat content does not have to be listed, but manufacturers might declare it voluntarily.
You can also look for “hydrogenated” or “partially hydrogenated” in the ingredients list.
However, manufacturers only have to declare hydrogenation if a specific vegetable oil is listed . If the ingredient is generic “vegetable oil”, the manufacturer doesn’t have to specify whether that oil has been hydrogenated.
So, for certainty, look for products that specifically list the unsaturated fats they use as ingredients (for instance, canola oil, sunflower oil or olive oil), as these would have to include the extra detail.
Don’t stress about cooking with oils at home, as they don’t get hot enough to produce a meaningful amount of trans fats . Most margarines and shortenings in Australia have now been reformulated to have little to no trans fats .
If you are ordering takeaways or fast foods, deep frying at high temperatures can lead to a modest increase in trans fats. Choosing outlets that use liquid vegetable oils reduces this risk . Most fast-food chains in Australia use high-oleic canola oils or blends that don’t contain trans fats.
We don’t need to turn into chefs overnight
At the end of the day, trans fats are not necessary, nor are they health-promoting.
But we don’t need to overhaul our lives, cook every meal from scratch or track every gram of fat we eat.
With a little bit of label-reading, a few simple swaps, and a general pattern of choosing foods made with plant-based oils instead of solid fats can give you the confidence you are minimising your exposure to trans fats.
Emma Beckett is senior lecturer, Nutrition and Food Science, Australian Catholic University.
