By Simon J. Evans, PhD
Fat is bad for you – at least that’s what we were told for a long time. More recently, we’re told that some fat is good for you, like olive oil and fish oil. Then there are the downright “evil” fats we’ve been hearing so much about, like trans fats. Unless you’re someone who spends a lot of time figuring out all this advice, it can be more than a little confusing.
Now it turns out that the type of fat we eat may contribute to our risk of depression as well. But before getting into that, let’s try to simplify how fats are different.
We can really lump fats into 4 main categories:
First, we have saturated fats. This is the kind you get from butter, heavy cream, and animal fat, like that tasty marbled fat running through your prime rib. Eating too much saturated fat is linked with heart disease and can play a role in clogging up your arteries. Although we can’t avoid saturated fat completely (and probably shouldn’t), we can be careful about not taking in too much of the stuff.
Second, we have monounsaturated fats, which is what you get in olive oil. This type of fat has been found to be heart-healthy and probably brain-healthy as well. Like all fats, monounsaturated fat still carries a calorie load, so you don’t want to pour it down your throat. But if you replace the saturated fats you eat with monounsaturated – like using olive oil-based spread instead of butter – this can help overall heart and vascular health. And since your brain needs a huge blood supply, improving vascular health helps feed your brain as well.
Third, we have polyunsaturated fats. There are tons of different kinds of these fats, including omega-3s, and this is what you largely get in fish oil. It is also why canola oil is better than corn oil for cooking, because the polyunsaturated fats in canola oil are healthier.
Finally, we have trans fats. Similar to saturated fats, trans fats can increase your risk for heart disease and stroke. Most of the trans fats we eat are not natural and get into our foods because of the way we process them, especially through “partial hydrogenation,” which is used to “improve” the texture of many oils. Way back in the day, we actually thought that replacing saturated fat with trans fat was a good thing. Now we know that wasn’t such a good idea and are trying to get trans fats out of our food supply completely.
So, let’s get back to risk for depression. A new study followed more than 12,000 people in Spain to see if the type of fat they ate contributed to risk for depression.
What the researchers found was that people who ate more trans fat had higher rates of depression. And the more trans fat they ate, the higher the risk. We have known for some time that trans fat is bad for you, but this is the first time a study has linked it to depression. The study also confirmed what other studies have shown – the more monounsaturated or polyunsaturated fat the people ate, the less likely they were to become depressed.
In this study, eating saturated fat also increased the odds for getting depressed, but not at a level that was “statistically significant,” meaning the results were not strong enough in this study to really say for sure that eating saturated fat increases depression risk. Still, we know too much saturated fat is bad for your heart, so that’s reason enough to try to avoid it.
The bottom line is that the type of fat you eat matters when it comes to becoming depressed. Avoiding trans fats (which you can find listed on all food package labels) and getting monounsaturated and polyunsaturated oils into your diet is a good thing for your mood.
This is not to say that changing the kind of fat you eat should be your only strategy to prevent or treat depression, and it certainly shouldn’t replace professional help in managing depression symptoms. But watching this part of your diet may help your treatment work better and tip the scales in your favor.
Dietary Fat Intake and the Risk of Depression: The SUN Project (2011), Sanchez-Villegas et al. PLOS One, 6(1)e16268