When talking diet and nutrition there is probably no subject more polarizing than fat. We have been raised to view dietary fat as “bad” and many admonish fat-heavy diets as the source of increased incidence of heart attack, stroke and cancer. The movement against fat has been so strong and the message so well received that an entire industry has developed to capitalize on the perception that fat is the source of all our ills.
However, research is beginning to reveal that fat may not be as bad as we have been led to believe and that it may, in fact, be healthful when taken in the right amounts and from the right sources. Some even go so far as to suggest that a specific diet built exclusively on the consumption of specific varieties of fat can be therapeutic and the answer for neurological conditions that include autism, epilepsy, Alzheimer’s and Parkinson’s disease.
In order to keep ourselves armed with all the appropriate information in the discussion of dietary fat, let’s take a quick look at the different varieties of dietary fat, their health benefits or consequences, and healthful food sources of each so that we can include or exclude them to the degree that we see fit.
Dietary Fat 101
An important first step in understanding the importance of healthy fats is to better understand how they are classified so that we can group them according to their benefit. The easiest way of going about this is to separate all the varieties of fat according to their degree of saturation, otherwise known as the number of double bonds located along the carbon backbone of each fatty acid chain.
In their most basic form, dietary fats are chains of carbon atoms that have hydrogen atoms attached. If each carbon atom in the fatty acid chain has a hydrogen atom attached, it is known to be “saturated” with hydrogen atoms, hence the name saturated fat. Fatty acid chains that are missing hydrogen atoms are known as monounsaturated (lacking complete saturation at one point) or polyunsaturated (lacking saturation at multiple points) fats, respectively. When a fatty acid chain is fully saturated, each carbon atom has two hydrogen atoms attached, which tells us that no double carbon bonds exist. However, when a fatty acid is unsaturated, hydrogen atoms are missing and in order to “stabilize” the chain a double bond forms. Monounsaturated fats are missing two hydrogen atoms and contain one double carbon bond and polyunsaturated fats are missing more than two hydrogen atoms and have two or more double carbon bonds.
Here’s a picture of a saturated and unsaturated fatty acid chain for you:
In conjunction with the number of double bonds along the chain of an unsaturated fatty acid, location is also important in identify the potential health benefits of dietary fat. For example, omega-3s contain a double bond between the third and fourth carbon atoms along the fatty acid chain starting at the end opposite the carboxyl (COOH) group. The unsaturated fat illustrated above shows what an omega-3 essential fatty acid would look like if they weren’t limited by the number of carbon atoms that preceded the double bond, or point of unsaturation (The chain above has only 10 carbon atoms and omega-3s need at least 16).
If your head is spinning with all this talk of carbon atoms and double bonds, don’t worry because now that we have hashed out a few of the molecular basics of dietary fat we can move onto the really fun stuff!
Fatty Acid Health Benefits
At this point you have probably deduced the fact that structure imparts function and that the different varieties of dietary fat have different capabilities in promoting or hindering health. Lets take a moment to discuss how each variety and their unique structure and function may impact health.
Saturated fats have been pinned by the American Heart Association as causing an increase in LDL, “bad”, cholesterol in the blood, which they link to an increased risk of heart disease risk and stroke. This association has been made because it is believed that as more cholesterol circulates through the body, the more likely it is to attach to the walls of arteries, restricting blood flow and raising blood pressure to increase the likelihood of heart attack and stroke. However, research is beginning to surface that suggests this association is invalid, inflammation caused by a low fat/high carb diet may actually be to blame for heart disease, and that saturated fats are an integral component in a health and balanced diet. Trans fats fall under that saturated umbrella, which are actually built from unsaturated fatty acids that have been bombarded with hydrogen atoms to artificially saturate them and make the more functional in food production. Regardless, trans fats are definitely bad and should be avoided at all costs.
According to the American Heart Association, monounsaturated and polyunsaturated fats can help reduce “bad” cholesterol levels and lower the risk of heart disease and stroke. Unfortunately, unsaturated fats, because of the missing hydrogen atoms, are chemically unstable and prone to oxidation. When unsaturated fats are allowed to oxidize via the application of heat or exposure to air, light or moisture, they can mutate and start producing free radicals that break down the membranes surrounding our cells, which can greatly impair their ability to function. Making matters worse, oxidation end products can be mutagenic and carcinogenic, altering our DNA and encouraging the growth of cancer-forming cells.
Omega-3 and omega-6 essential fatty acids fall into the polyunsaturated category, which are known to be essential in that they must be obtained from diet. These two fats, distinct in their molecular structure from other polyunsaturated fats, interact the body in very unique ways. Omega-3 essential fatty acids are known to prevent blood clots, protect against irregular heartbeat, and promote brain health and development. Omega-6 polyunsaturated fats are healthful in moderation, but they are used extensively in the food production process, which means that we typically consume way more with respect to our intake of omega-3, which can promote inflammation, immune dysfunction and disease. Our collective consumption of omega-6 to omega-3 is somewhere around 16:1 where our body would prefer a ratio to be closer to 4:1 or better. Many believe that a 1:1 omega-6:omega-3 ratio was what our ancestors maintained and the reason why they were able to avoid the scourge of lifestyle diseases like CVD, cancer, autoimmune disease and diabetes that have come to define the late 20th and early 21st centuries.
Fatty Acid Foods
Although we know that certain fats are extremely unhealthful and should be avoided at all costs, specifically trans fats, our understanding of which fats are “good” and which are “bad” is in the middle of a pretty dramatic shift. This shift makes it difficult to give blanket recommendations for how much of each variety we should consume, but if eat real, unprocessed foods; strive for diversity in our food patterns; and limit the consumption of pro-inflammatory processed foods we can almost effortlessly get ourselves close to the ideal fat intake that promotes health and a long, happy, and active life.
Healthful real foods high in mono- and polyunsaturated fats include avocados, nuts, seeds, olive oil and ethically sourced fish. Food that can help shift our omega-6:omega-3 ratio closer to that of our ancestors include fatty fish like salmon, mackerel and sardines; nuts and seeds like walnuts, flax and hemp; in addition to grass-fed and -finished beef. Superior sources of saturated fats include coconut, coconut oil, and animal foods like beef, pork, poultry, eggs, dairy, butter, and ghee.
{For more on the Healing Power of Healthy Fats, here is a recent VWJ post on the therapeutic value of coconut and a ketogenic diet.}
Similar to the benefits of purchasing organic fruits and vegetables over the conventional varieties, organic nuts, seeds and oils, in addition to ethically sourced animal foods, contain more of the healthful fats and fewer unhealthful ones that the body needs. The nutritional benefit of high quality, healthy fat foods also includes the fat-soluble vitamins that they contain. Fat soluble vitamins A, D, E and K serve many functions in the body and are an essential component of a healthy diet and wellness plan.
Wow! That was a lot of information!
Dietary fat is a very polarizing subject in the worlds of diet and nutrition. However, popular opinion is changing and health and nutrition professionals around the world are starting to embrace how healthful and potentially therapeutic healthy fats can be. Ask us your questions in the comments section!
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