We hear so many negatives about fat: “You should avoid fatty foods” – “This is a low-fat food item!” – “All fat is bad”. Yet, we know that fat is one of the three macronutrients that our bodies need to stay healthy. So what’s going on here? Suddenly we have good fat and bad fat, saturated and unsaturated – and heck, even polyunsaturated fats. It’s enough to confuse anyone! So today, we’re going to delve into fats and see if we can’t pull back the veil on this odd nutrient.
The Good, The Bad And The Ugly
In trying to understand fats, I think it’s important to define just what we’re dealing with in the first place, that way, we can look at each one and see how our bodies use them, and truly understand why the particular fat might be good or bad for our health.
So it turns out there are 4 different types of fats:
Monounsaturated fats – the good
These fats are liquid at room temperature and mainly come from plant sources. You can find monounsaturated fats in things like avocado, canola or olive oils and nuts. This unsaturated fat only contains one double bond in its chemical structure, which is why it’s called “mono”.
Polyunsaturated fats – the… also good
Similar to it’s “mono” cousin, polyunsaturated oils are liquid at room temperature, but have two or more double bonds in their chemical structure. The polyunsaturated family also contains Omega-3 and -6 fatty acids in their family tree. Polyunsaturated fats can be found in vegetable oils like sunflower or sesame oils, but also in walnuts, fish and shellfish.
Saturated fats – the bad
Saturated fats are solid at room temperature and found mostly in animal products like dairy products and meat – butter is a good example. Red meats are higher in saturated fats than fish or poultry, and you can also find saturated fats in tropical oils like palm or coconut oil. These are “the bad” referred to in this section
Trans fats – the ugly
Most trans fats start out as one of the two unsaturated fats above, but are modified in an industrial process that adds hydrogen to them to make them more solid. You can recognize many of these by the name “partially hydrogenated oils” on a label. In fact, trans fats are so “ugly”, the FDA banned artificial trans fats (partially hydrogenated vegetable oil) in the US in 2015.
Chemistry side note: we talked a lot about saturated, unsaturated, hydrogen and double bonds in the above definitions, and it turns out that’s all related. in a fatty acid chain, there are places for hydrogen atoms to connect to carbon atoms in the fatty acid chain. In a saturated chain, there are no double bonds left, and the maximum amount of hydrogen atoms have bonded with the carbon (get it? It’s SATURATED with hydrogen). In an unsaturated chain, that’s not the case, there are still areas where carbon hasn’t bonded with the chain. So in a trans fat, we humans have used a chemical process to TRANSform an UNsaturated fat into a saturated fat.
So why is this bad for you? Well, a saturated fat is a more stable molecule, and therefore harder for the body to break up than an unsaturated fat. This allows it to store more energy than carbohydrates or proteins (hence fats are higher in calories than carbs or protein – more on that here), but it also makes it more likely to “stick” to the body as cholesterol. But we’ll get more into that below.
So Why Are Fats So Important?
Well, as you can tell from above, some fats are important and some are anti-important! We’ll look at each one specifically in a minute, but as a general overview, fats support cell growth and they help supply your body with energy. Fats inside your body help to keep you warm and provide protection for your internal organs (biological padding!). From a dietary standpoint, fats help you absorb vitamin A, vitamin D and vitamin E (if you want to know about what these do, check out the micronutrients post) which are fat-soluble – meaning they only dissolve in fat and they’re also a source of essential fatty acids.
As we know though, not all fats are created equal, so what does each one do once consumed?
I’m lumping poly and mono together since they’re both in the good category. These two are part of a healthy diet and help reduce high blood cholesterol levels. The presence of an omega-6 fatty acid in poly-unsaturated fat called linoleic acid (one of 2 essential fatty acids attainable only through diet) has been shown to lower the risk of coronary heart disease. Interestingly, it doesn’t seem like it’s understood WHY linoleic acid has its cholesterol lowering effects.
The general rule with these fats is to use them to REPLACE the use of saturated fats in your diet. This may seem difficult given that these fats are generally liquid at room temperature, but replacing butter with something like olive oil is definitively better for your health (this may also explain the ingenuity behind things like avocado toast!)
Generally speaking, unsaturated fats can help:
- Reduce high blood cholesterol
- Decrease the risk of heart disease
- Lower triglyceride levels
- Lower blood pressure
So what are some food sources that you can add into your diet or use to replace bad fats that you may be consuming?
- Sunflower seeds
- Pine Nuts
- Sesame oil or sunflower oil (replace lard – or Crisco)
- Olive, Canola and Peanut Oils (replace butter)
- Avocados (replace butter)
- Oily fish – such as salmon, mackeral, herring, lake trout, or albacore tuna (according to the American Heart Association, 2 3.5 oz. servings per week)
Now we’re getting into the ugly. Not the “you’ll never be able to fix this.” ugly, more the “man was I drunk last night and who is this in my bed?” kind of ugly. In all seriousness, Saturated fats are not good for you – but they’re still allowable in your diet – in small doses. The American Heart Association recommends around 13 grams per day for a 2,000 calorie diet. The Mayo clinic is a little more forgiving, allowing up to 22 grams per day for a 2,000 calorie diet. To give you an idea, 1 tablespoon of butter has about 7 grams of saturated fat. So as said before on this blog – read your labels! The takeaway here is: use your judgement, try to stick between 13 and 22 grams per day and you’re probably fine – or better still, talk to your doctor and use their judgement – they know far more than some guy on the internet.
So why care? well, saturated fats have been shown to increase the levels of LDL (low-density lipoproteins) cholesterol in your blood, which increases your risk of both heart disease and stroke. I don’t now about you, but those are two words I want nothing to do with! While Saturated fat also increases your HDL (high-density lipoproteins – the good cholesterol), the good doesn’t offset the bad.
Sciency stuff dumbed down:
Why is LDL cholesterol bad for me and HDL cholesterol good for me?
Well, LDL is sticky stuff, it tends to clump up and stick to the walls of your arteries. Over time, this buildup of LDL “plaque” adds up, clogging your arteries, veins and heart and making it harder for your heart to work to move blood through your body.
Imagine a straw. When you suck up a drink through it, you’re able to easily create suction in your mouth, pulling the liquid through the straw and into your mouth. Your heart works in the opposite way, creating pressure to push fluids (in our case blood) through your veins and arteries to deliver oxygen and nutrients where your body needs them. Now, back to our straw example, imagine that the inside of the straw has sucked up something like a piece of fruit into it, narrowing the opening. Obviously, you can still suck up drink through the straw, but it’s a lot harder, until you’re able to clear away the blockage.
Inside our bodies, LDL is the piece of fruit. Over time it builds up, narrowing the opening and making our hearts have to work harder until the blockage is cleared. If the blockage isn’t cleared, and instead continues, it can build up inside the heart, actually slowing or keeping blood and oxygen from reaching parts of the heart, which can cause chest pain, or a heart attack.
HDL is similar to LDL, except that it tends to only stick to other cholesterol, pulling it away and back to the liver where it can be processed and removed from the body. Essentially, HDL can metaphorically help clear the fruit from the straw.
So how do you raise your HDL? I swear I’m not making this up – exercise several times per week has been shown to improve HDL. Dietarily, olive oil can help increase HDL levels, as can a lower carb diet (although I’m suspicious of the source of carbohydrates consumed in the study). Also, eating your fatty fish can help and as odd as it sounds – eating purple produce. Purple produce contains antioxidants known as anthocyanins, which have been shown to raise HDL cholesterol (among other things).
So let’s look at the bad news, where might you be consuming saturated fats?
- Foods fried in saturated fats
- Fatty beef
- Whole and (2%) reduced fat milk
Try to replace the above with fruits and vegetables, whole grains, low-fat dairy products, lean poultry, fish and nuts, and limit ed meat intake. Additionally, replacing these foods with any from the unsaturated fats list is a good idea.
Just don’t. I should just stop here. They’re just bad news. Trans fats are a double whammy against your health. They not only raise your LDL levels, but they also LOWER your HDL levels. Our metaphor here is: Your straw is getting plugged up by fruit, and the fruit is actively fighting off your attempts to clear away the blockage. So trans fats carry all the negatives associated with Saturated Fats, but none of the positives, and in fact reduce the positives.
Additionally, it’s been shown to increase the risk of developing type 2 diabetes. oh yeah, and also certain types of cancers. Seriously, just stay away from this stuff.
So where does this monster hide (courtesy of the Mayo Clinic)?
- Shortening is usually made from hydrogenated vegetable oil, so things using it like baked goods, cookies, pie crusts or ready made frosting.
- Chips and microwave popcorn
- Deep fried foods like french fries, fried chicken or doughnuts
- Refrigerated dough products – canned biscuits, cinamon rolls and frozen pizzas
- Non-dairy creamer and stick margarine
The take-away, as before – read your labels folks! some of the items on the list above may be ok to eat, but only if they’re not made with – or cooked in – trans fats. But that’s not all:
A tip also from the Mayo Clinic:
“In the United States if a food has less than 0.5 grams of trans fat in a serving, the food label can read 0 grams trans fat. This hidden trans fat can add up quickly, especially if you eat several servings of multiple foods containing less than 0.5 grams a serving.
When you check the food label for trans fat, also check the food’s ingredient list for partially hydrogenated vegetable oil — which indicates that the food contains some trans fat, even if the amount is below 0.5 grams. Eating several portions of foods containing some trans fat may boost your total intake of trans fat to a level high enough to affect your health.”
Back in the beginning of this article, I mentioned that the FDA has banned partially hydrogenated vegetable oil in the US, which is good news for those of us living here. But you’ll still want to check foods listed above to be safe.
Lastly, there ARE naturally occurring sources of trans fats – beef, lamb and butterfat for example, but there are not enough studies to determine if these naturally occurring sources have the same negative effects as the man-made kind.
Wrapping It Up
Hopefully that sheds some light on this macronutrient, exposing why some fats are good, some fats, not so much, and some should just be reclassified as the boogeyman! Look for foods that contain mono- or poly-unsaturated fats, and limit your consumption of items containing saturated fats and you’ll do your body – and specifically your heart – some serious favors!
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The American heart Association – Trans Fats
NCBI – Dietary linoleic acid and risk of coronary heart disease: a systematic review and meta-analysis of prospective cohort studies
The ins and outs of unsaturated fats
Mayo Clinic – Trans fat is double trouble for your heart health
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