You’ve probably already heard: fat is back. For the past 40 years, low-fat has been the most commonly recommended approach for a healthy diet. But now, more and more research is bringing to light the benefits of a diet containing adequate healthy sources of fat, as well as the downsides of the high-carbohydrate diet that often results when fat is reduced. One of the biggest diet trends right now is the “Keto Diet” which is on the complete opposite end of the spectrum from the diets of the past several decades. It emphasizes high intakes of fat and extremely low intakes of carbohydrates. It can feel confusing with the media blowing nutrition studies out of proportion, and studies that are biased due to their funding sources, saying “low-fat is best” or “high-fat is best”. Fat can be a polarizing topic! There is so much contradictory information out there. So is fat good for us? Are all fats created equal? Let’s dive into the topic of healthy fats.
Benefits of fats in the diet
As a holistic nutritionist, when asked if a high-fat or low-fat diet is good for us, my answer will be “it depends”. It depends on the whole picture and we recognize people as individuals with individual needs. What is helpful for one person’s health may harm another’s. However, including a moderate intake of healthy fats is generally recommended and is helpful for optimal wellness. The quality of the fat is more important than the exact quantity (more on choosing quality fats below). Fat is necessary for many of the body’s functions:
● Component of cell membranes, giving them structure and maintaining a strong barrier against pathogens
● Brain function and mental wellness
● Healthy skin
● Blood sugar balance
● Absorption of fat-soluble nutrients such as vitamins A, E, and D
● Hormone production
● Energy source
What makes a fat a “healthy fat”?
The healthiness of a fat is largely determined by its molecular structure. Fatty acid molecules are chains of carbon with hydrogen atoms attached and “saturation” refers to how many hydrogens are attached. A saturated fat has the maximum amount of hydrogen attachments. An unsaturated fat has places along the chain where there is a carbon to carbon double bond instead of a hydrogen attachment.
You likely already know about trans fats being a “bad” fat. The advice to avoid them still stands. Trans fats are, in general, generated during the processing of oils and fats. Food manufacturers “hydrogenate” unsaturated oils like canola or soy, turning a liquid oil into a solid form (think: margarine). This process causes the fat molecule to now be in “trans configuration”. This was originally done to avoid natural saturated fats such as butter and replace them with a “healthier” option, but unsurprisingly, what was created in a lab is worse for our well-being than what is found in nature. Foods that contain manmade trans fats are margarines, crackers, cookies, packaged snack foods, and fast foods.
You’ll notice that many foods now claim to be trans fat-free. An important thing to note is that food manufacturers are allowed to claim zero trans fats so long as the amount is below 0.5g per serving. This is a convenient loophole for these companies. They can write up nutrition fact labels for very small serving sizes in order to have the ability to claim zero trans fats for an absurdly small portion that may have up to 0.5g of trans fats. For example, “4 crackers” as a serving size to stay under the limit. Most people don’t eat just 4 small crackers. Another thing to be aware of is that some food manufacturers have switched to another way of processing oils to avoid generation of trans fats, but these manipulated fats may be just as dangerous, if not more. They are also using filler ingredients to create a solidified product from these processed oils. A general recommendation is to simply avoid most processed food unless it is from a trusted natural/organic company that uses high quality fats. Cooking at home with healthy fats eliminates trans fat ingestion to almost zero (there are some naturally occurring trans fats, although they have been found to not cause the same health issues that manmade trans fats do).
Naturally occuring trans fats are interesting because they are actually beneficial for our health. Meat contains a beneficial trans fat called CLA (conjugated linoleic acid). It has potent antioxidant properties that slow the growth of cancer. It also reduces risks of type 2 diabetes and heart disease. As usual, the source of the meat is important: grass-fed meats and dairy products contain up to 500% more CLA than grain-fed meats and dairy products.
In terms of what an intake of even small amounts of (manmade) trans fats does to our health, known health conditions include cardiovascular disease, cancer, and high LDL cholesterol.
In the past, saturated fat was singled out as a “bad” fat and something to limit as much as possible, swapping it out for unsaturated fats instead. However, newer research shows that saturated fat is not necessarily “bad” and can actually be health-promoting. There are over 30 different kinds of saturated fat. Saturated fats are fat molecules that contain the maximum amount of hydrogen attachments. Due to their molecular structure, they are typically solid or semi-solid at room temperature. Examples include butter/ghee, coconut oil, and animal fats.
Recent studies have debunked the myth that saturated fat intake causes disease. Not only did the recent, large-scale studies indicate no correlation between saturated fat intake and disease, they also showed that processed vegetable oils (the ones that have been recommended in place of saturated fats) are linked to higher instances of cardiovascular disease. A key piece to understanding how saturated fats are not harmful: the intake of saturated fats are not equal to the presence of saturated fats in the bloodstream and tissues. Surprisingly, higher intakes of carbohydrates are linked to higher levels of saturated fats in the bloodstream compared to ingestion of saturated fats. The body takes ingested carbohydrates and turns the excess into fat. It is the fats in our bloodstream and tissues, not the saturated fats in our diets, that are linked to cardiovascular disease. Additionally, many types of saturated fat are beneficial for our health. They can be anti-inflammatory and help us absorb fat-soluble vitamins. Saturated fats are the most stable due to their molecular structure, making them resistant to oxidation damage when heated (unlike the more fragile unsaturated fats). This makes them great for cooking. Choose organic and/or pasture-raised sources that are unrefined or have been minimally processed.
Polyunsaturated fats are fat molecules that contain multiple places on the fatty acid chain where it is “unsaturated” (missing a hydrogen attachment and contains a carbon double bond). This kind of fat is generally recognized as a “good” fat and it is the category that the “omega” fats fall into, ie omega-3 and omega-6 fats. These are considered “essential” fatty acids. This means that our bodies cannot manufacture them but they require them for functions in the body, so we must ingest them in the diet. Omega-3 fats are found in foods such as fatty fish and other seafood, eggs, grass-fed meat, flaxseeds, algae, and walnuts. Omega-6 fats are found in nuts, seeds, grains, beans, refined vegetable oils, and processed foods. Both omega-3 and omega-6 fats are necessary, but the ratio is critical.
A healthy diet should contain a ratio of omega-6:omega-3 between 2:1 and 4:1. The problem is that the modern, highly-processed, grain-dense diet contains much higher amounts of omega-6 fats. In excess, these fats cause inflammation in the body. An adequate amount of omega-3s, which are anti-inflammatory and health-promoting, is necessary to balance out the effects of omega-6s. The outdated, oversimplified advice to swap out saturated fats like coconut oil and butter for polyunsaturated highly-processed oils such as soybean oil, canola oil, and corn oil is a major culprit in the issue of excessive intake of omega-6 fatty acids. Another reason for elevated omega-6 levels in the modern diet is grain-fed animal products. Animals that are fed their natural diet of grass produce meat that contains up to 4 to 5 times more of the beneficial omega-3 fatty acid compared to grain-fed animals. As always, the source matters. For optimal health, choose whole-food minimally processed sources of the essential omega-6s like nuts and seeds, and ample amounts of omega-3 from wild-caught fish, pasture-raised eggs and meat, flax, algae, and walnuts. Many people also benefit from taking a fish oil supplement which contains high levels of omega-3 fatty acids. If you choose to take one with the advice of your holistic healthcare practitioner, choose one that sources the oil from wild-caught fish.
These fatty acids have one spot along the fatty acid chain where there is a carbon to carbon double bond and no hydrogen attachment. Monounsaturated fats are great fats and are generally not argued over. Foods that contain this type of fat include avocados, olive oil, canola oil, nuts, nut oils, and animal fat. Like polyunsaturated oils, these oils can be unstable and easily damaged by heat. This is why, even though canola oil contains this health-promoting fat type, it is not considered a healthy fat. Most canola oil is heavily processed, bleached, and heated, rendering it damaged and unfit for consumption.
Monounsaturated fats are helpful for protection against heart disease, lowering blood pressure, improving insulin sensitivity, and LDL cholesterol (the “bad” cholesterol). It’s a good idea to include plenty of unrefined sources of this fat, while being mindful about how much they are heated.
My hope is that this article helps to break down the nutrition confusion around the highly controversial topic of fats. To sum it up:
● The healthiness of a fat depends on its source and whole-food, naturally-raised/wild-caught, organic sources are best for optimal health.
● Trans fats that are manmade are toxic and can be avoided by choosing foods that are not made in a factory with processed oils. Trans fats found in nature are actually health-promoting.
● The advice to avoid saturated fats at all costs and opt for polyunsaturated fats instead is unsubstantiated and overly simplistic- many of the common sources of polyunsaturated fats in the modern diet are toxic. There are over 30 different types of saturated fats and many of them are beneficial for health. Choose quality sources as mentioned above.
● Polyunsaturated fats are the “omega” fats and they are necessary in the diet. Be mindful of the omega-6 to omega-3 ratio and aim for between 2:1 and 4:1.
● Monounsaturated fats are great for health. Include quality sources of them often.
● This guide lists particular foods as sources of particular kinds of fat, however it is important to note that whole-foods are complex so they contain a mix of different types of fat in varying proportions.
Further Reading & References:
● Staying Healthy with Nutrition by Elson M. Haas, MD
● FOOD what the heck should I eat? by Mark Hyman, MD
● Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk: A Systematic Review and Meta-analysis
● Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study
Contributed by Melanie Maxwell, R.H.N.