Originally posted May 2019 / Updated March 2023

Within the past twenty years, there has been a radical shift in the attitude towards dietary fats. Before this time, fats were vilified, and many nutritional experts told the public that eating fat promoted weight gain, heart disease, and other illnesses. Low-fat products were mainstream, and some individuals even went on entirely fat-free diets in their quest for health.

The overwhelming consensus is that some fats are essential to good health and can help protect against most chronic degenerative diseases. With several different kinds of fat found in food and a lot of misinformation, it is crucial to know what types of fat are suitable and what should be avoided. 

The top 3 healthy fats to incorporate into your diet are monounsaturated fats, essential fatty acids, and long-chain omega-3 fatty acids. This article will explain why these types of fats are so important to your health and what are the best sources.

Understanding the Terminology of Fats

The backbone of fat is a chain of carbon atoms. Carbon is capable of bonding to four additional atoms. A saturated fat is a fat molecule where all the available bonding sites are occupied with another atom, such as another carbon atom or a hydrogen or oxygen atom. 

Unsaturated fat has bonding sites left unoccupied. The two neighboring carbon atoms will form a double bond to take up the slack. A fat molecule with one double bond is called a monounsaturated fat. 

Molecules with more than one double bond are called polyunsaturated fats. When an unsaturated fat contains the first double bond at the third carbon, it is called an omega-3 fatty acid. If the first double bond is at the sixth carbon, it is an omega-6 fatty acid; if it occurs at the ninth carbon, it is an omega-9 fatty acid. 

Only two fatty acids are essential for humans because they can serve as the base for other required fats. Linoleic acid (LA) is the essential omega-6 fatty acid, and linolenic acid (ALA) is the essential omega-3 fatty acid. Both LA and ALA have a length of 18 carbons. LA has two double bonds with the first at the sixth carbon, while ALA is also 18 carbons in length, it has three double bonds, with the first at the third carbon. 

Both LA and can be converted by the body into longer and more unsaturated fatty acids. For example, ALA can be elongated and unsaturated further to produce eicosapentaenoic acid (EPA), which has 20 carbons in length and five double bonds with the first at the third carbon making it an omega-3 fatty acid. EPA can also be elongated and unsaturated further to produce docosahexaenoic acid (DHA), which is 22 carbons in length and has six double bonds. EPA and DHA are the chief omega-3 fatty acids in cold-water fish and fish oil supplements. 

Good Fat versus Bad Fat

What makes a fat “bad” or “good” has a lot to do with the function of fats in our cellular membranes. Membranes are made mostly of fatty acids and serve as a barrier in creating a constant internal environment. The cell membranes are designed to be flexible and fluid in nature. These functions are largely determined by the type of fat you consume. 

A diet composed mostly of “bad fats” like saturated fat from animal sources, trans fatty acids (from margarine, shortening, and other sources of hydrogenated vegetable oils), and high in cholesterol results in membranes that are much less flexible and fluid than the cell membranes in a person who consumes optimal levels and ratios of monounsaturated and polyunsaturated fatty acids. 

The type of fats in cell membranes are extremely important to proper cellular function. According to modern pathology, or the study of disease processes, an alteration in cell membrane function is one of the central factors in the development of virtually every chronic health condition. Without a healthy membrane, cells lose their ability to hold water, vital nutrients, and electrolytes. They also lose their ability to communicate with other cells and be controlled by regulating hormones, including insulin. 

In addition to their role in cell membranes, omega-6 and omega-3 fatty acids are transformed into regulatory compounds known as eicosanoids. These compounds act like hormones and perform many important tasks, including mediating inflammation. Balancing omega-6 and omega-3 fatty acids is important in adequately regulating body functions. For example, too much omega-6 fatty acids and too little long-chain omega-3 fatty acids EPA and DHA in the diet lead to more inflammation. Correcting this imbalance is very important in preventing virtually every chronic disease.

The Best Sources of Monounsaturated Fats

Monounsaturated fats are heart-healthy fats in olive oil, avocados, nuts, and seeds. The best source of oleic acid, perhaps the most important monounsaturated fat, is extra-virgin olive oil, which contains 73% of its total fat content as oleic acid.

Olive oil has been a staple of the Mediterranean diet for over 3,000 years. The health benefits of extra-virgin olive oil have been extensively studied and are well-documented across several decades. Studies have shown that extra virgin olive oil helps reduce the risk of cardiovascular disease, type 2 diabetes, and overall mortality. Studies have also shown that olive oil reduces inflammatory markers, including a marker known as C-reactive protein. The high levels of antioxidant polyphenols in this oil enhance its ability to protect against inflammation and oxidative stress. 

Avocado and avocado oil are an alternative to nuts, seeds, and olive oil as a source of monounsaturated fat. Avocados are a nutrient-rich food. For example, one avocado will have about 1,000 mg of potassium. That is three times the potassium content of an average banana. Like olives and olive oil, avocados are a heart-healthy food that contains antioxidant polyphenols. Over a dozen human clinical trials show avocado consumption improves blood lipid profiles by lowering LDL-cholesterol and increasing HDL-cholesterol. 

Eating one tablespoon of olive or avocado oil or eating ¼ cup of raw nuts and seeds daily are easy steps to increase the intake of monounsaturated fats in the diet.

The Best Sources of Essential Fatty Acids

Nuts and seeds are the best sources of the essential fatty acids LA and ALA. But since omega-6 fat intake is generally high and omega-3 fatty acid intake tends to be insufficient in most diets, four the focus should be on foods high in ALA and low in LA, such as flaxseed oilflaxseeds, and chia. Other nuts and seeds that provide good levels of ALA are pumpkin seeds and walnuts.

Flaxseed oil and ground flaxseeds are the most concentrated source of ALA and have an excellent monounsaturated fat (oleic acid) content. 

Having one tablespoon of flaxseed oil or ¼ cup of olive or avocado oil and eating ¼ cup of raw nuts and seeds daily are easy steps to increase monounsaturated fats intake diet.

Table 1. Nuts and Seeds Providing High ALA and Low LA


Total fat %

Alpha-linolenic acid %

Linoleic acid %

Oleic acid %

Saturated fat* %













Pumpkin seed












*Saturated fat in nuts is primarily medium chain fats rather than the longer saturated fats contained in animal foods.

The Best Sources of Long-chain Omega-3 Fatty Acids

Although it is possible to convert ALA from flaxseed oil, walnuts, chia, and other foods to the longer chain omega-3s EPA and DHA, it is not efficient, especially in men. Including preformed EPA and DHA from fish and fish oil or algal-based supplements is vital to intake the longer-chain omega-3 fatty acids adequately.

Significant research indicates that higher blood levels of the long-chain omega-3 fatty acids, but not ALA, are associated with excellent health and longevity. Regarding reducing all-cause mortality, pooled analysis from 17 studies examining the associations between blood omega-3 fatty acid levels and risk for all-cause mortality found the risk for death from all causes was significantly lower (by 15-18%) in the group with the highest levels of long-chain omega-3 fatty acids in their blood. No link was seen between alpha-linolenic acid levels and longevity. This analysis supports the importance of adequate intake levels of preformed long-chain omega-3 fatty acids through diet or supplementation.

Highly concentrated fish oil supplements provide a purified source of EPA and DHA free from heavy metals, environmental contaminants, lipid peroxides, and other harmful substances. These high-quality fish oils are available in capsules, emulsions, and liquid forms. Use products that provide at least 60% omega-3 fatty acids and take a dosage that will give a minimum of 800 to 1,000 mg of EPA+DHA as that level ensures adequate intake.

If you are a vegetarian or a vegan, taking an algae-based EPA+DHA supplement is an alternative to fish oils. The dosage recommendation is the same as for fish oils, 800 to 1,000 mg per day of EPA+DHA. 


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