Fats: A Brief Primer
Before I delve into omega-3 fats further, let’s take a few moments get to know the different types of fats. Don't worry, I'll be brief and I promise there won't be a pop quiz on the subject matter. This is just so you have a basic understanding of dietary fats.
Fats are one of three macronutrients, along with protein and carbohydrates which provide us with energy, or calories. Fats provide 9 kilocalories per gram (kcal/g), while protein and carbohydrates provide 4 kcal/g. This means that fats are more energy dense than both protein and carbohydrates.
Fats can be further divided into categories depending on their chemical structure. While each fat has a similar “skeleton” of a glycerol head and hydrocarbon chain, fats differ in the length and structure of that hydrocarbon chain (see image below). Some hydrocarbon chains are connected only by single bonds and completely surrounded by hydrogen atoms (these are saturated fats) while others have some double bonds and less hydrogen atoms (these mono- and polyunsaturated fats). These differences in chemical structure account for their different biochemical properties and functions within the body.
Saturated fats are primarily found in animal products (meat and dairy) but is also a major component of coconut and palm oil. Monounsaturated fats are found in olive oil, avocados and some nuts, while polyunsaturated fats are found in nuts, seeds, and marine animals. It is important to note that fat in food is usually found as a mixture of different fats, and rarely are 100% of one type of fat. For example, olive oil mainly consists of monounsaturated fat but also contains a certain portion of saturated and polyunsaturated fats. When we say a food contains a certain type of fat, we are usually talking the type of fat in which it contains most of.
Now that you’ve got a basic understanding of what fats are, let’s talk a little more about omega-3 fats....
What are omega-3 fats?
Although our body has the ability to make some types of fats from scratch, omega-3 fats are not one of them. Found mainly in marine animals, nuts and seeds, omega-3 fats need to be obtained through diet. This makes it essential that we choose foods sources of these fats. If you’ve ever heard the term essential fatty acids, this refers to exactly that.
The omega-3 fats that we are most concerned with are:
- Alpha-Linolenic Acid (ALA)
- Eicosapentaenoic Acid (EPA)
- Docosahexaenoic Acid (DHA)
The quick and dirty of these omega-3 fats is that ALA is the most easily obtained omega-3 fat in the western diet. And that’s a good thing because, not only do we need ALA on its own, it is also used to make EPA and DHA. However, the conversion ratio from ALA to EPA and DHA isn’t very high. So although our body can technically make EPA and DHA, it can only do so in very little quantities. For these reasons, we consider DHA and EPA to be conditionally essential, in other words we can make them but in order to get enough for your body it is best to obtain them through our diet, as well.
What do omega-3 fats do?
One of the most significant functions of omega-3 fats is their role in the anti-inflammatory pathway. That is, omega-3 fats have anti-inflammatory properties. While some inflammation in the body is needed (it's part of our body’s healing process), sometimes inflammation can get a little carried away. Many disease processes trigger the body’s inflammatory pathway or are characterized by chronic, low level inflammation. This chronic inflammation is not good. The theory behind dietary omega-3s is that if the diet is sufficient in them, the body’s anti-inflammatory pathways can be given a boost.
- Omega-3 fats are a component of cell membranes.
- DHA is involved with both visual and neurological development, and found in the retina and the brain’s grey matter.
- Omega-3 fats are associated with lower risk of cardiovascular disease.
- ALA intake is associated with a lower C-reactive protein (CRP) level, a marker of inflammation.
- Omega-3 fats may help lower blood triglycerides.
- May be associated with a slower rate of cognitive decline.
- May be helpful in the treatment of rheumatoid arthritis.
- May decrease risk of ischemic stroke.
- Omega-3 fats are involved with blood clotting.
- Omega-3 fats are involved with fertility, cell division and growth.
*it should be noted that, like many areas of nutrition research, there is an abundance of conflicting studies on the benefits of omega-3 fats, from both diet and supplements (hence the conditional word 'may' in some above statements). That being said, a Cochrane Review of the evidence on omega-3s concludes that there isn’t enough evidence to advise people to stop taking supplements or including dietary sources of omega-3’s in their diet. There likely is a benefit, or in least in some people there is a benefit to ensuring adequate omega-3 fats.
How much do I need?
While there is no official intake recommendation for the fats EPA and DHA, there are guidelines established for their precursor, ALA. The following levels are recommended for ALA:
A note about conversion of ALA to EPA and DHA:
As mentioned previously, ALA can be converted by our body’s enzymes to EPA and DHA (that’s good news!) but the efficacy of this conversion is quite low (not so good news). Our body’s ability to make EPA and DHA is influenced by several factors including:
- Sex - women are much better than men at making EPA and DHA (likely due to estrogen). For EPA, studies indicate a conversion rate of 21% for women and 8% for men; and for DHA 9% for women and 0-4% for men.
- Genetics - some individuals possess genes that convert ALA to EPA and DHA more efficiently.
In addition to non-modifiable factors such as sex and genetics, our body’s ability to convert ALA to EPA and DHA is influenced by the amount of omega-6 fats in our diet. Omega-6 fats, found in seed oils and many commercially made food products, compete for the same enzymes which convert ALA to EPA and DHA…and they win. Diets high in omega-6 fats have been shown to decrease conversion to EPA and DHA by 40-50%. It appears that there is an optimal ratio of omega-6 to omega-3 fats in the diet, and if this ratio is exceeded, conversion to EPA and DHA will be hindered.
What does this mean in a practical sense? Well, there are three things you can do:
- Ensuring you obtain good quality sources of EPA and DHA (so you don’t need to convert them).
- Obtaining adequate amounts of ALA, and
- Avoiding an overabundance of omega-6 fat sources (i.e. sunflower, corn oil, safflower oil, soybean oil and processed/fast foods made with these oils). This is not say that you can’t consume these oils but it’s probably wise to diversify your cooking oil choices to include extra virgin olive oil, avocado oil, cold-pressed grapeseed, cold-pressed canola oil, flaxseed (for salad dressings) and/or coconut oil (yes, even coconut oil!). By diversifying the fats you use while cooking, you’ll be ingesting a variety of fats and (hopefully!) not overload yourself with one type, especially those omega-6 oils which hinder EPA/DHA formation.
- Flaxseed oil (1 tbsp) - 7.3 g
- Walnuts, English (¼ cup pieces) - 2.8 g
- Chia seeds, dried (1 tbsp) - 1.9 g
- Flaxseed, ground (1 tbsp) - 1.6 g
- Walnut, oil (1 tbsp) - 1.4 g
- Canola oil (1 tbsp) - 1.3 g
- Radish sprout (½ cup) - 0.42 g
- Edamame, boiled (½ cup) - 0.34 g
- Wheat germ (2 tbsp) - 0.24 g
EPA and DHA
- Herring, pacific (3 oz) - 1.06 g EPA, 0.75 g DHA
- Salmon, chinook (3 oz) - 0.86 g EPA, 0.62 g DHA
- Sardines, pacific (3 oz) - 0.45 g EPA, 0.74 g DHA
- Salmon, atlantic (3 oz) - 0.28 g EPA, 0.95 g DHA
- Oysters, pacific (3 oz) - 0.75 g EPA, 0.43 g DHA
- Salmon, sockeye (3 oz) - 0.45 g EPA, 0.60 g DHA
- Trout, rainbow (3 oz) - 0.4 g EPA, 0.44 g DHA
- Mackerel, atlantic (2.5 oz) - 0.38 g EPA, 0.52 g DHA
- Tuna, canned, white (3 oz) - 0.04 g EPA, 0.19 g DHA
As you can see, it’s not exactly difficult to obtain enough omega-3 fats, if you know which foods to choose from. Arming yourself with a little nutrition knowledge can really go a long way.
If you eat fish, then getting enough omega-3 fats is pretty straightforward. The general consensus is that if you eat two 2.5 oz servings of fatty fish each week (this is about the size of a deck of cards), you will get enough omega-3 fats.
For those who do not eat fish or don’t think 2 servings a week is feasible, focusing on a few key foods rich in ALA can really help out on the omega-3 front. Flaxseed oil, in particular, is a very good source of ALA with 1 tablespoon providing more than 4 and 6 times the daily ALA requirement, for men and women respectively. It’s a great neutral oil to use in salad dressings, added to smoothies or drizzled on top of steamed veggies. Other fantastic sources of plant-based omega-3 fats are walnuts (great as a snack, on hot cereal, or on salads), chia seeds (in chia pudding, sprinkled on hot cereals, in smoothies or mixed in peanut butter) or ground flaxseed (added to homemade salad dressings, hot cereals, in pasta sauce or on yogurt). Consistently incorporating these 4 foods in your diet, in some way or another, will make it easy to get the amount of ALA you need. Of course, any of the other sources of ALA listed above, will also do. Just pick a few and have the on a regular basis.
What are your favourite sources of omega-3 fats? How do you incorporate them into your diet?