Lipids are also involved in the synthesis of hormones like testosterone and estrogen, as well as in the production of bile, which in turn allows us to digest. They smoothen our cell membranes, isolate & protect our vital organs and play a role in body temperature regulation. Fatty substances are also essential for the well-functioning of the nervous system.
Good fat, bad fat
Generally speaking, fats are essential to the proper functioning of the body, but they aren’t all equal. Some fats have a positive effect on health while others are not as interesting and even harmful. The goal then is to include the former in our plate as much as possible, and reduce consumption of the latter.
From a nutritional and chemical standpoint, there are four types of fats: monounsaturated fats, polyunsaturated fats, saturated fats and trans fats. They differ in their chemical structure, which explains their different effects on our health.
1. Mono-unsaturated fats
Goal: get more
Monounsaturated fats (or omega-9) are usually in liquid form at room temperature. Our body is able to produce omega-9 with saturated fats, but it’s still worth consuming more of it because of its positive effect on our cardiovascular health: they reduce the bad cholesterol (LDL) and increase the good cholesterol (HDL) in the blood. Monounsaturated fats also help reduce blood pressure and increases our sensitivity to insulin.
Sources: olive oil, cashews, hazelnuts, avocados & macadamia nuts.
2. Polyunsaturated fats
Goal: get more but aim for balance
These types of fats are also liquid at room temperature, but they’re more susceptible to heat & oxidation than monounsaturated fats. Omega-3 & omega-6 are two types of polyunsaturated fats that we hear a lot about.
In total, there are 3 types of omega 3: ALA (alpha linolenic acid) that come from plant sources, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) that often come from animal sources or from certain seaweed.
Of all omega-3s, only the ALA are considered essential, which means the body must absolutely get them from foods and cannot make them on its own. The human body can use ALA to produce the other two types of omega-3, DHA and EPA. It isn’t the body’s most optimal mechanism, however, because there is a lot of waste associated to this production. It’s best to include a variety of foods rich in omega-3 to get the right amount.
Omega-3 is crucial for our nervous system, hormones and cardiovascular health. The benefits they bring to our blood lipids, our eyes & brain development have been well proven scientifically.
Omega-6 also have an interesting effect on our cardiovascular health. Because our body does not produce them, we need to find it in our diet. Consumed in too high doses can actually counter the use of omega-3 in the body. Our North-American diet is often too rich in omega-6 so the goal would be to have some, but not excessively.
Sources: walnuts as well as flax, chia and hemp seeds are good sources of AAL omega-3. Soy, corn and sunflower oils are all sources of omega-6.
3. Saturated fats
Goal: get some, but not too much
For a long time, we’ve heard that saturated fats were bad for us because they tended to increase cholesterol. But in the last few years, talk has shifted and many studies have pointed to saturated fats more likely having a neutral effect on us.
It makes sense because the impact on one’s health cannot be measured by only looking at the effect fat has on cholesterol. There are a lot of other factors to consider. For instance, saturated fats also contribute to increasing good cholesterol so it would seem to have an overall neutral effect on our blood lipids.
Sources: Solid at room temperature, saturated fats are found in a few plant sources such as palm & coconut oils, and have a slightly different chemical composition that the saturated fats found in animal products, which would explain why they have less of an impact on our blood lipids. Note that there is a difference between virgin coconut and palm oils and the industrial versions that are highly transformed.
4. Trans fats
Goal: avoid as much as possible
Almost all trans fats are synthetic saturated fats. By bombarding unsaturated oils with hydrogen at room temperature, the food industry artificially created saturated fats.
The reason for this is that, first of all, trans fats are much cheaper than most other saturated fats yet they give similar results when used in pastries, for example. Trans fats contribute to that melt-in-your-mouth texture you find in many industrial foods. Trans fats are also resistant to high temperatures and have a long shelf life.
For now, the consensus is that we should avoid consuming them all together because they are absolutely useless and unhealthy. Health Canada is working on a complete ban of the use of trans fats that should be in effect by 2018.
Sources: You can find trans fats anywhere you see the ingredients “hydrogenated vegetable oil” or “partially hydrogenated”.
So the verdict is to have more omega-3 type monounsaturated and polyunsaturated fats because of their positive effects on human health. We also want to strike a balance between omega-3 and omega-6. By doing so, we are also introducing more variety in our plate. Definitely avoid overconsumption of these two. Trans fats are to be avoided all together.
Now you know. Fats not only add flavour and texture to our dishes, but a judicious intake of them is just as beneficial to your health. So, bring on the fats!