Topic 5: Macronutrients - Lipids

Lipids

To everyone's delight, we are going to be finishing up the macronutrients this week with lipids. However, just to warn you, in my opinion, lipids are the most complicated to explain of the macronutrients. There are so many types, classifications, and functions. Most of these classifications really require a decent background in organic chemistry and biochemistry. For example, lipids are first classified into simple, complex lipids, precursor and derived lipids. Then further classification into saturated, monounsaturated, and polyunsaturated. We will try to keep this as practical as possible while still giving us some depth on the subject.

When talking about saturated vs unsaturated we must discuss what saturation even means. It is technically talking about the amount of hydrogen molecules surrounding the carbons in a lipid molecule. Points of un-saturation means having a double bond versus a single bond. This is essentially worthless to know for the most part, but I just wanted to be thorough. 

What this translates to is the stiffness of the fatty acid which changes melting point. At room temperature animal fat which is mostly saturated fat is solid at room temperature. Mono and polyunsaturated fats are typically liquid at room temperature. 

C = Carbon, H = Hydrogen, O = Oxygen in the illustration below. 

This is why coconut oil is solid at room temperature and olive oil is a liquid.

Fats have diverse functions in the body. The body can use fats as an energy source, in which they contain 9kcal per gram. This is double that of protein and carbohydrates. This means every gram of fat you consume has twice the amount of calories to its macronutrient counterparts. The body uses lipids such as phospholipids to make the cell membrane of every cell. Within the membrane is also cholesterol molecules which are complex lipids.

Cholesterol also is the backbone to lipid hormones such as Calcitriol (Active Vitamin D), Testosterone, Estrogen, Progesterone, Cortisol. Glycolipids are molecules that are part lipid and part carbohydrate which make up important components such as myelin, the insulation of our nervous system.

On a side note, lipid peroxidation or the improper breakdown of fats (fats going rancid) is a major source of free radicals in the body, underlining the need for abundant antioxidants in the diet.

We will have an entire article in the future about inflammation but the key players in the inflammatory pathways are special fats called Eicosinoids. Needless to say, fats are vitally important in your body.

As I stated in the previous article, I am a very big fan of Professor T. Colin Campbell and his research in the field of nutritional biochemistry. According this the best available research, the amount of fat in the human diet should be around 5-10% on average.

This means that on the hypothetical 2000kcal diet, 5-10% of that would be 100kcal to 200kcal of fat per day. And since we talked about fat containing 9kcal per gram, we just do some easy math and find out that this particular diet would want to take in 11-22grams of fat per day.

Ok, so the math is out of the way. Now the tantalizing question is what types of fats should we eat? That question is in my opinion is many times more difficult to answer. With the 80/10/10 diet, and specifically talking about fat, lets be serious 11-22 grams per day, on a 200kcal diet of course, is not very much fat at all. In fact you will likely not consume many at all overt fats, or foods that are very dense in fats. So that makes the question even harder because you have to strategically pick the biggest bang for our bucks.

For me I ask the question, what fats can my body make, and what fats can my body not make? This makes our selection much easier because the majority of fats I described above our body can make on its own quite well. However, there is a group of fats that our bodies cannot make, these are call the Essential Fatty Acids, or EFAs for short. These are the mysterious Omega-3 Fatty acids that has been getting a lot of attention lately.

Omega-3 fatty acids are polyunsaturated fats that are found in a few different flavors. Examples being EPA, DHA, ALA. These fats are again not made by the body, and absolutely must be in our diets in order for our bodies to function correctly. DHA and EPA are almost exclusively found in animal foods, however ALA is found abundantly in plant foods.

As always it is better to eat whole, unprocessed foods, but this is especially important for the fat category. Extracted of fats from whole foods is oil. Nutritional speakers such as Professor T. Colin Campbell, Dr. John McDougall, and especially Dr. Caldwell Esselstyn are against oils of any kind this includes "healthy oils" such as olive oil. Studies have shown oils to wreck havoc on our cardiovascular system. This is likely due to lipid peroxidation as mentioned before. When fats are found in whole foods, they have antioxidants and other nutrients to protect the fatty acids and keep them non-rancid. However, when extracted into oils, they are at the mercy of oxidation and we literally end up eating free-radicals. This is not good.

The only oil that I have seen in studies that seems to avoid this vessel damage is fish oil. Fish oils because it is almost completely Omega-3 does have some protective effect even in an oil form.

We as consumers must use what we know about the essential fatty acids to pick a high quality supplement, if we decide go this direction. Look on the side of the label at the amount of fat per serving. Then immediately look at the EPA and DHA content of fish oil supplements, and ALA in flax and chia seeds. Flax seeds need to be ground before consuming or they will not absorb. This can be accomplished by either buying ground flax seeds or grinding them yourself in an electric coffee grinder or high speed blender. Lets look at some examples.

This is the popular Krill fish oil, which is supposedly better than other fish oils. However lets say we are trying to get 1-2grams of EFA in our diet daily, that is 1000-2000mg. In one gram of fat we see 85mg of EPA and 45mg of DHA. This would mean in order to get to our 1-2 gram goal we would need 8-16 servings. Hmm seems like that bottle would go pretty fast.

Lets take a look at a different label.

So for every one gram of fat here we get 600mg of EPA and DHA. So in order for us to meet our 1-2 gram goal we will take 2-3 servings. Much more reasonable no? 

Ok last label. 

Here we have some ground flaxseeds. We can see that for every 4.8 grams of fat we get 2.8 grams of Omega-3, in the form of ALA as earlier stated. In order to make our 1-2 gram target we would need less than the 2 Tablespoon serving.

So just as a last piece of discussion for Omega-3s. EPA and DHA are from animal sources and ALA is from plants. EPA and DHA are ready to be used by the body, but ALA must be converted to EPA and DHA in the body. The conversion is not perfect, but vegetarians and vegans can still maintain healthy levels of omega-3s (DHA/EPA) with a diet rich in ALA.

Take home points

1) Lipids have a diverse range of vital functions in the body.

2) Our goal for dietary fat should be 5-10% of our daily caloric intake.

3) We should focus on getting the EFAs above all other dietary fats as our bodies cannot manufacture these. 

4) Our bodies make cholesterol and saturated fats quite well, and are not needed in our diets in high quantities.

5) As aways whole foods, whole foods, whole foods.

I look forward to hearing any questions or comments!

To your health,

Dr. Peavler