The Truth About Fats

The Truth About Fats and Oils: the good, the bad, and the in-between

Fat gets a bad rap even though it is a nutrient that you need in your diet, just not too much. Not all fats are equal. Learn all about dietary fats, which ones actually boost your health and how getting too much or too little affects your health !

Does my body need fats ? Yes, it does. Dietary fats are essential to give your body energy and to support cell growth. They also help protect your organs and help keep your body warm. Fats help your body absorb some nutrients and produce important hormones, too. Your body definitely needs fat.

Dietary fats are found in both plant and animal foods. They supply calories and help with the absorption of the fat-soluble vitamins A, vitamin D, vitamin E, and vitamin K. Some also are good sources of two essential fatty acids—linoleic acid and α-linolenic acid.

All dietary fats are composed of a mix of polyunsaturated, monounsaturated, and saturated fatty acids, in varied proportions (see Dietary Fats chart). For example, most of the fatty acids in butter are saturated, but it also contains some monounsaturated and polyunsaturated fatty acids. Oils are mostly unsaturated fatty acids, though they have small amounts of saturated fatty acids too.

Table 1. Fatty acid content of different oils, nuts, fruits, seeds and animal products

[Source ¹]

For years, fat was a four-letter word and fat has been the bogeyman of bad health. We were urged to banish it from our diets whenever possible. We switched to low-fat foods. But the shift didn’t make us healthier, instead our low fat diet (& high sugar diet) are making us fatter and more un-healthy than ever before. This is because the world universally (based on faulty and misleading scientific conclusion) made a major public health ruling to eat low fat in our diet. This is partly because we cut back on healthy fats as well as harmful ones and partly the increase of refined sugar and high fructose corn syrup that have been added to our highly processed foods in order to make them tasty and palatable due to the lower fat/oil contents (emphasis of eating low-fat foods).

Increasingly, however, research is showing that not all fats are equal. Some oils and fatty foods contain chemicals called essential fatty acids, which our bodies need for good health.

Consuming high amounts of saturated fats linked to increased heart disease risk ! ², ³, ⁴, ⁵. Heart and vascular disease includes heart attacks, angina, strokes, sudden cardiovascular death and the need for heart surgery.

In a new study appearing online in the Journal of the American College of Cardiology, Dr. Frank Hu and colleagues found that people who replace saturated fat (primarily found in meats and dairy foods) with refined carbohydrates do not lower their risk of heart disease, whereas those who replace saturated fats with unsaturated fats or whole grains lower their heart disease risk ⁶.

That study shows the importance of eliminating trans fat and replacing saturated fat with unsaturated fats, including both omega-6 and omega-3 polyunsaturated fatty acids ⁷. Different types of dietary fat had different associations with mortality, the researchers found. Trans fats—on their way to being largely phased out of food—had the most significant adverse impact on health. Every 2% higher intake of trans fat was associated with a 16% higher chance of premature death during the study period. Higher consumption of saturated fats was also linked with greater mortality risk. When compared with the same number of calories from carbohydrate, every 5% increase in saturated fat intake was associated with an 8% higher risk of overall mortality (see Figure 1. Dietary Fats and Mortality Rates). Conversely, intake of high amounts of unsaturated fats—both polyunsaturated and monounsaturated—was associated with between 11% and 19% lower overall mortality compared with the same number of calories from carbohydrates. Among the polyunsaturated fats, both omega-6, found in most plant oils, and omega-3 fatty acids, found in fish and soy and canola oils, were associated with lower risk of premature death.

These findings support current dietary recommendations to replace saturated fat and trans-fat with unsaturated fat.

• Scientists concluded that saturated fat should be no more than 5 percent to 6 percent of daily calories. So, for a diet of 2,000 calories a day, that would mean no more than 120 of them should come from saturated fats. That’s about 13 grams of saturated fats a day ⁸.

Figure 1. Dietary Fats and Mortality Rates

[Source ⁹]

The Effect of Cutting Down Fat You Eat and Your Weight

Do all fats have the same number of calories ? Yes. There are nine calories in every gram of fat, regardless of what type of fat it is. Fats are more energy-dense than carbohydrates and proteins, which provide four calories per gram. (Source ¹⁰).

Consuming high levels of calories – regardless of the source – can lead to weight gain or being overweight. Consuming high levels of saturated or trans fats can also lead to heart disease and stroke. Health experts generally recommend replacing saturated fats and trans fats with monounsaturated fats and polyunsaturated fats – while still maintaining a nutritionally-adequate diet.

The ideal proportion of energy from fat in your food and its relation to your body weight is not clear. This review (source ¹¹) looked at the effect of cutting down the proportion of energy from fat in your food on body weight and fatness in both adults and children who are not aiming to lose weight. The review found that cutting down on the proportion of fat in your food leads to a small but noticeable decrease in body weight, body mass index and waist circumference. This effect was found both in adults and children. The effect did not change over time.

Trials where participants were randomised to a lower fat intake versus usual or moderate fat intake, but with no intention to reduce weight, showed a consistent, stable but small effect of low fat intake on body fatness: slightly lower weight, BMI and waist circumference compared with controls. Greater fat reduction and lower baseline fat intake were both associated with greater reductions in weight. This effect of reducing total fat was not consistently reflected in cohort studies assessing the relationship between total fat intake and later measures of body fatness or change in body fatness in studies of children, young people or adults.

How do you know the difference between good fats and bad fats ?

Fats are essential for living organisms. Fatty acid molecules have a variable length carbon chain with a methyl terminus and a carboxylic acid head group ¹². They can be categorized based on the degree of saturation of their carbon chains. Saturated fatty acids possess the maximal number of hydrogen atoms, while monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) have one, or two or more, double bonds, respectively.

The proportions of fatty acids in a particular fat determine the physical form of the fat:

• Fats with a higher amount of polyunsaturated and monounsaturated fatty acids are usually liquid at room temperature and are referred to as “oils.”
• Fats with a higher amount of saturated fatty acids are usually solid at room temperature and are referred to as “solid fats.” Fats containing trans fatty acids are also classified as solid fats, although they may or may not be solid at room temperature.

Your body needs some fat from food. The two essential fatty acids most important to good health are omega-3 and omega-6. But we need these in the right balance in order to protect our hearts, joints, pancreas, mood stability, and skin. It’s a major source of energy. It helps you absorb some vitamins and minerals. Fats help your body absorb fat-soluble vitamins A, vitamin D, vitamin E and vitamin K and stores them in the liver and in fatty tissues for future use.

Fat is needed to build cell membranes, the vital exterior of each cell, and the sheaths surrounding nerves. It is essential for blood clotting, muscle movement, and inflammation. Cholesterol, which is created by fat, produces important hormones like estrogen and testosterone. For long-term health, some fats are better than others. Good fats include monounsaturated and polyunsaturated fats. Bad ones include industrial-made trans fats. Saturated fats fall somewhere in the middle.

All fats have a similar chemical structure: a chain of carbon atoms bonded to hydrogen atoms. What makes one fat different from another is the length and shape of the carbon chain and the number of hydrogen atoms connected to the carbon atoms. Seemingly slight differences in structure translate into crucial differences in form and function.

1) Unsaturated Fats (called the Good Fats) come mainly from vegetables, nuts, seeds, and fish. They differ from saturated fats by having fewer hydrogen atoms bonded to their carbon chains. Healthy fats are liquid at room temperature, not solid. There are two broad categories of beneficial fats: monounsaturated and polyunsaturated fats.

Good fats can improve blood cholesterol levels, ease inflammation and stabilize heart rhythms. Most of us don’t get enough of these healthy unsaturated fats. The traditional Greek diet gets up to 30 percent of its calories from monounsaturated fats, mostly from olive oil.

There are two broad categories of beneficial fats: monounsaturated and polyunsaturated fats. Scientists have now established that trans fats found in many fast foods, bakery products and margarines increase the risk of cardiovascular disease through inflammatory processes.

Two types of Unsaturated fats (Good Fats):

a) Monounsaturated Fats are found in high concentrations in olive oil, peanut oil, canola, avocados, almonds, safflower oils, hazelnuts, pecans, pumpkin seeds and sesame seeds and most nuts. Monounsaturated fats also are part of most animal fats such as fats from chicken, pork, beef, and wild game. When you dip your bread in olive oil at an Italian restaurant, you’re getting mostly monounsaturated fat. Monounsaturated fats have a single carbon-to-carbon double bond. The result is that it has two fewer hydrogen atoms than a saturated fat and a bend at the double bond. This structure keeps monounsaturated fats liquid at room temperature. Good sources of monounsaturated fats are olive oil, peanut oil, canola oil, avocados, most nuts, as well as high-oleic safflower and sunflower oils. The carbon-carbon double bond found in monounsaturated or polyunsaturated fatty acids can exist in the cis or trans configuration. When the two hydrogen atoms are on opposite sides of the double bond, the configuration is called trans. When the hydrogen atoms are on the same side of the double bond, the configuration is called cis.

The discovery that monounsaturated fat could be healthful came from the Seven Countries Study during the 1960s. It revealed that people in Greece and other parts of the Mediterranean region enjoyed a low rate of heart disease despite a high-fat diet. The main fat in their diet, though, was not the saturated animal fat common in countries with higher rates of heart disease. It was olive oil, which contains mainly monounsaturated fat. This finding produced a surge of interest in olive oil and the “Mediterranean Diet” a style of eating regarded as a healthful choice today.

Although there’s no recommended daily intake of monounsaturated fats, the Institute of Medicine recommends using them as much as possible along with polyunsaturated fats to replace saturated and trans fats.

Figure 2. Monounsaturated Fatty Acids Structure

b) Polyunsaturated Fats (polyunsaturated fatty acids) are found in high concentrations in sunflower, corn, soybean, flaxseed oils, walnuts, flax seeds, hemp seeds, pine nuts, sesame, cottonseed oils, pumpkin seeds and fish.

Polyunsaturated fatty acids (PUFAs) can be further subdivided on the basis of the location of the first double bond relative to the methyl terminus of the chain. For example, n-3 and n-6 fatty acids are two of the most biologically significant polyunsaturated fatty acid classes, and have their first double bond on either the third or sixth carbon from the chain terminus, respectively. The final carbon in the fatty acid chain is also known as the omega carbon, hence the common reference to these fatty acids as omega-3 or omega-6 PUFAs. The distinction between omega-6 and omega-3 fatty acids is based on the location of the first double bond, counting from the methyl end of the fatty acid molecule (see Figure 4). Omega-6 fatty acids are represented by Linoleic acid (LA) (18:2ω-6) and Arachidonic acid (AA) (20:4ω-6) and omega-3 fatty acids by Alpha-linolenic acid (ALA) (18:3ω-3), Eicosapentaenoic acid (EPA) (20:5ω-3) and Docosahexaenoic acid (DHA) (22:6ω-3).

Long-chain n-3 and n-6 PUFAs are synthesized from the essential fatty acids: alpha-linolenic acid (ALA) and linoleic acid (LA), respectively. Basic structures of these two parent PUFAs are shown in Figure 3 and Figure 4. An essential fatty acid cannot be made by the body and must be obtained through dietary sources. Animals and humans have the capacity to metabolize essential fatty acids to long-chain derivatives. Because the n-6 and n-3 pathways compete with one another for enzyme activity, the ratio of n-6 to n-3 PUFAs is very important to human health. An overabundance of fatty acids from one family will limit the metabolic production of the longer chain products of the other. The typical Western diet provides n-6 and n-3 PUFAs in a ratio ranging from 8:1 to 25:1 ¹², values in severe contrast with the recommendations from national health agencies of approximately 4:1 ¹³. Lowering the n-6:n-3 ratio would reduce competition for the enzymes and facilitate the metabolism of more downstream products of ALA.

Mammalian cells cannot convert omega-6 to omega-3 fatty acids because they lack the converting enzyme, omega-3 desaturase. Omega-6 and omega-3 fatty acids are not interconvertible, are metabolically and functionally distinct, and often have important opposing physiological effects, therefore their balance in the diet is important ¹⁴.

This study showed a balanced omega-6/omega-3 ratio 1–2/1 is one of the most important dietary factors in the prevention of obesity, along with physical activity. A lower omega-6/omega-3 ratio should be considered in the management of obesity ¹⁴.

Because most diets are already very rich in n-6 PUFAs, greater focus needs to be placed on incorporating n-3 PUFAs into the diet. Dietary sources of n-3 PUFAs are readily available but in limited quantities. Many foods contain alpha-linolenic acid (ALA), including certain vegetable oils, dairy products, flaxseed, walnuts and vegetables ¹⁵. Fatty fish, such as mackerel, herring and salmon, provide an excellent source of the long-chain derivatives of ALA, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) ¹³.

Omega-3 fatty acids are a type of polyunsaturated fats found in seafood, such as salmon, trout, herring, tuna, and mackerel, and in flax seeds and walnuts. EPA and DHA are long chain n-3 fatty acids found in seafood. Omega-3 fats are one important type of polyunsaturated fat. Polyunsaturated fats are essential fats. That means your body can’t produce these and they’re required for normal body functions. So you must get them from food. Polyunsaturated fats are used to build cell membranes and the covering of nerves. They are needed for blood clotting, muscle movement, and inflammation.

A polyunsaturated fat has two or more double bonds in its carbon chain. There are two main types of polyunsaturated fats: omega-3 fatty acids and omega-6 fatty acids. The numbers refer to the distance between the beginning of the carbon chain and the first double bond (see Figure 4.). Both types offer health benefits.

Figure 3. Polyunsaturated Fatty Acids Structure

Polyunsaturated fatty acids (PUFAs) can be further subdivided on the basis of the location of the first double bond relative to the methyl terminus of the chain. For example, n-3 and n-6 fatty acids are two of the most biologically significant polyunsaturated fatty acid classes, and have their first double bond on either the third or sixth carbon from the chain terminus, respectively. The final carbon in the fatty acid chain is also known as the omega carbon, hence the common reference to these fatty acids as omega-3 or omega-6 PUFAs.

Figure 4. Omega-3 fatty acids (ALA, EPA & DHA) and Omega-6 fatty acids (LA & AA) structure

Note: Omega-6 fatty acids are represented by Linoleic acid (LA) (18:2ω-6) and Arachidonic acid (AA) (20:4ω-6) and Omega-3 fatty acids by Alpha-linolenic acid (ALA) (18:3ω-3), Eicosapentaenoic acid (EPA) (20:5ω-3) and Docosahexaenoic acid (DHA) (22:6ω-3).

Eating polyunsaturated fats in place of saturated fats or highly refined carbohydrates reduces harmful LDL cholesterol and improves the cholesterol profile. It also lowers triglycerides.

We don’t eat nearly enough omega-3, which can reduce our risk for heart disease and cancer. Good sources of omega-3 fatty acids include fatty fish such as salmon, mackerel, and sardines, all green leafy vegetables, flaxseeds, walnuts, canola oil, and unhydrogenated soybean oil.

Omega-3 fatty acids may help prevent and even treat heart disease and stroke. In addition to reducing blood pressure, raising HDL, and lowering triglycerides, polyunsaturated fats may help prevent lethal heart rhythms from arising. Evidence also suggests they may help reduce the need for corticosteroid medications in people with rheumatoid arthritis. Studies linking omega-3s to a wide range of other health improvements, including reducing risk of dementia, are inconclusive, and some of them have major flaws, according to a systematic review of the evidence by the Agency for Healthcare Research and Quality.

Omega-6 fatty acids have also been linked to protection against heart disease. Foods rich in linoleic acid and other omega-6 fatty acids include vegetable oils such as safflower, soybean, sunflower, walnut, and corn oils.

The latest research on nuts by the Harvard School of Public Health found that women who reported eating a half serving of peanut butter or a full serving of nuts five or more times a week showed as much as a 30% reduced risk of developing type 2 diabetes. And eating other nuts, like almonds, walnuts, and pecans, have been shown to have heart healthy benefits, including lowering “bad” LDL cholesterol. (Remember, walnuts are also a source of omega-3.)

2) Saturated Fats:

Saturated fats are common in the American diet. They are solid at room temperature — think cooled bacon grease, butter, beef tallow, coconut oil, ghee or pork lard. Common sources of saturated fat include lard, butter, ghee, red meat, palm oil, whole milk and other whole-milk dairy foods, cheese, coconut oil, and many commercially prepared baked goods and other foods ¹⁶. Coconut, palm kernel, and palm oil are called oils because they come from plants. However, they are solid or semi-solid at room temperature due to their high content of short-chain saturated fatty acids. They are considered solid fats for nutritional purposes. They also are found in other animal fats, such as pork and chicken fats and in other plant fats, such as nuts.

The word “saturated” here refers to the number of hydrogen atoms surrounding each carbon atom. The chain of carbon atoms holds as many hydrogen atoms as possible — it’s saturated with hydrogens.

Figure 5. Saturated Fatty Acids Structure

According to the American Heart Association Advisory ¹⁷, cardiovascular disease was lowered by about 30 percent, similar to the effect of cholesterol-lowering statin drugs when vegetable oil replaced saturated fat in the diet. The switch to healthier oils also was associated with lower rates of death from all causes. The American Heart Association recommends aiming for a dietary pattern that achieves 5% to 6% of calories from saturated fat, that’s about 13 grams of saturated fats a day ¹⁸.

[Source Data from US Department of Agriculture food composition tables ¹⁹].

Note: A zero value equals <0.5 g/100 g.
*Primary safflower and sunflower oils of commerce.

Is Saturated Fat Bad for you ?

Yes ²⁰, ¹⁷, ¹⁸. The main sources of saturated fat to be decreased are dairy fat (butter), lard (pork), beef tallow, palm oil, palm kernel oil, and coconut oil. A diet rich in saturated fats can drive up total cholesterol, and tip the balance toward more harmful LDL cholesterol, which prompts blockages to form in arteries in the heart and elsewhere in the body. For that reason, most nutrition experts recommend limiting saturated fat to under 10% of calories a day.

Recent published review on available clinical trials and scientific studies involving 15 studies with over 59,000 participants ²¹ — found the evidence on (current) to March 2014 —- that cutting down on saturated fat led to a 17% reduction in the risk of cardiovascular disease (including heart disease and strokes), but no effects on the risk of dying. The review  ²¹ found no clear health benefits of replacing saturated fats with starchy foods or protein. Changing the type of fat we eat, replacing saturated fats with polyunsaturated fats, seems to protect us better, reducing our risk of heart and vascular problems. The greater the decrease in saturated fat, and the more serum total cholesterol is reduced, the greater the protection. People who are currently healthy appear to benefit as much as those at increased risk of heart disease or stroke (people with high blood pressure, high serum cholesterol or diabetes, for example), and people who have already had heart disease or stroke. There was no clear difference in effect between men and women.

However, some recent studies have also questioned the role saturated fat plays in heart disease and this has created confusion among patients, their physicians, and the public ²², ²³, ²⁴, ²⁵, ²⁶, ²⁷, ²⁸, ²⁹, ³⁰, ³¹. One meta-analysis of 21 studies said that there was not enough evidence to conclude that saturated fat increases the risk of heart disease, but that replacing saturated fat with polyunsaturated fat may indeed reduce risk of heart disease.

In a recent randomized clinical trials on saturated fat (published June 2017) ³² where the group that is assigned a diet lower in saturated fat is taught how to replace it with foods higher in ≥1 other macronutrients, typically carbohydrates or unsaturated fats, to maintain the same total energy intake. Other trials, often called controlled feeding trials, actually provide to the research participants their assigned diet high or low in saturated fat balanced with a similar amount of energy from another macronutrient. Essential to the interpretation of the results from these trials (and the reason for the divergent results in meta-analyses noted above) is the macronutrient composition of the comparator diet. Clinical trials that used polyunsaturated fat to replace saturated fat reduced the incidence of cardiovascular disease ²⁵, ³³. In contrast, trials that used mainly carbohydrates to replace saturated fat did not reduce cardiovascular disease. However, the types of carbohydrate-containing foods were often unspecified and typically included
sugar and other refined carbohydrates to maintain energy balance. Evidence from prospective observational studies indicates that carbohydrates from whole grains reduce cardiovascular disease when they replace saturated fat ³⁴.

Prospective observational studies, also called cohort studies, are conducted in large populations in which dietary intake is assessed at the beginning of the study
and in some studies reassessed repeatedly during the follow-up periods, and cardiovascular disease is assessed at various points during follow-up. In prospective observational studies, the participants eat whatever diet they themselves choose, and the researchers request that participants report their recent or past dietary history. Research participants in observational studies who eat a large amount of saturated fat eat less of various other macronutrients, usually carbohydrates, unsaturated fat, or both, to maintain energy intake. Participants who eat a comparatively small amount of saturated fat eat more carbohydrates or unsaturated fats. Because carbohydrates and unsaturated fats differ in their metabolic effects, it is necessary to evaluate the effects of low and high saturated fat intakes in the context of the replacement macronutrient. This is easier in a clinical trial because the trial controls the dietary intake but more complicated in observational studies in which the participants control their own diets.

Meta-analyses of prospective observational studies aiming to determine the effects on cardiovascular disease of saturated fat that did not take into consideration the replacement macronutrient have mistakenly concluded that there was no significant effect of saturated fat intake on cardiovascular disease risk ²⁹, ³⁵. In contrast, meta-analyses that specifically evaluated the effect of replacing saturated fat with polyunsaturated fat found significant benefit, whereas replacing saturated fat with carbohydrates, especially refined carbohydrates, yielded no significant benefit to cardiovascular disease risk ²⁸, ³¹, ³⁶. Thus, again, differences in the effects of the replacement or comparator nutrients, specifically carbohydrates and unsaturated fats, are at the root of the apparent discrepancies among studies and meta-analyses on whether lowering saturated fat reduces the risk of developing cardiovascular disease. In fact, the evidence to recommend reduction of saturated fat and its replacement by polyunsaturated and monounsaturated fat has strengthened as better methodology is more widely adopted for the analysis of dietary intake in observational studies. The study authors judge the evidence to favor  recommending n-6 polyunsaturated fat, that is, linoleic acid, stronger than monounsaturated fat to replace saturated fat because of the positive results of randomized clinical trials that used polyunsaturated fat compared with the paucity of trials that used monounsaturated fat ³⁷; the greater relative risk reduction for  polyunsaturated fats in observational studies ²⁸, ³¹, ³⁶; the greater reduction in LDL cholesterol with polyunsaturated fat ³⁸; and the regression of atherosclerosis in nonhuman primates by polyunsaturated but not monounsaturated fat ³⁹. However, progress in reducing cardiovascular disease would be enhanced by replacing saturated fat by either type of unsaturated fat. Two other major studies narrowed the prescription slightly, concluding that replacing saturated fat with polyunsaturated fats like vegetable oils or high-fiber carbohydrates is the best bet for reducing the risk of heart disease, but replacing saturated fat with highly processed carbohydrates could do the opposite.

Polyunsaturated fats are contained in canola oil, corn oil, soybean oil, peanut oil, safflower oil, sunflower oil, and walnuts. However, original high-linoleic varieties of safflower and sunflower oils are uncommon. High-oleic varieties of safflower and sunflower oil, olive oil, avocados, and tree nuts such as almonds, cashews, hazelnuts, pistachios, and pecans have mainly monounsaturated fats and are low in saturated fat.

Too much saturated fat in your diet can lead to heart disease and other health problems.

In large randomized clinical trials that used polyunsaturated fat to replace saturated fat reduced the incidence of cardiovascular disease ²⁵, ³³. Cardiovascular disease is the leading global cause of death, accounting for 17.3 million deaths per year, comprising 31.5% of total global deaths in 2013. Nearly 808 000 people in the United States died of heart disease, stroke, and other cardiovascular diseases in 2014, translating to about 1 of every 3 deaths.

This large cohort study ⁷ found that higher intake of saturated fat (found in foods like butter, lard, tallow and red meat) and especially trans fat (predominantly from partially hydrogenated vegetable oil), was associated with greater risk of mortality (death) when compared with the same number of calories from carbohydrate. When compared with carbohydrates, every 5% increase of total calories from saturated fat was associated with an 8% higher risk of overall mortality, and every 2% higher intake of trans fat was associated with a 16% higher risk of overall mortality ⁷. The study investigated 83,349 women from the Nurses’ Health Study (July 1, 1980, to June 30, 2012) and 42,884 men from the Health Professionals Follow-up Study (February 1, 1986, to January 31, 2012) who were free of cardiovascular disease, cancer, and types 1 and 2 diabetes at baseline ⁷. Dietary fat intake was assessed at baseline and updated every 2 to 4 years. Information on mortality was obtained from systematic searches of the vital records of states and the National Death Index, supplemented by reports from family members or postal authorities. Of the 126,233 participants who were followed up for as long as 32 years, the study found that higher intakes of saturated fat and trans-fat were associated with increased mortality, whereas higher intakes of polyunsaturated (PUFA) and monounsaturated (MUFA) fatty acids were associated with lower mortality. Replacing 5% of energy from saturated fats with equivalent energy from PUFA and MUFA was associated with reductions in total mortality of 27% and 13%, respectively ⁷.

People who replaced saturated fats with carbohydrates had only slightly lower mortality risk. In addition, replacing total fat with carbohydrates was associated with modestly higher mortality. This was not surprising, the authors said, because carbohydrates in the American diet tend to be primarily refined starch and sugar, which have a similar influence on mortality risk as saturated fats.

“Our study shows the importance of eliminating trans fat and replacing saturated fat with unsaturated fats, including both omega-6 and omega-3 polyunsaturated fatty acids. In practice, this can be achieved by replacing animal fats with a variety of liquid vegetable oils,” said senior author Frank Hu, professor of nutrition and epidemiology at Harvard Chan School and professor of medicine at Harvard Medical School.

This study is the most detailed and powerful examination to date on how dietary fats impact health. It suggests that replacing saturated fats like butter, lard, and fat in red meat with unsaturated fats from plant-based foods—like olive oil, canola oil, and soybean oil—can confer substantial health benefits and should continue to be a key message in dietary recommendations.

Meaning: Different types of dietary fat had different associations with mortality, the researchers found. Trans fats—on their way to being largely phased out of food—had the most significant adverse impact on health. Every 2% higher intake of trans fat was associated with a 16% higher chance of premature death during the study period. Higher consumption of saturated fats was also linked with greater mortality risk. When compared with the same number of calories from carbohydrate, every 5% increase in saturated fat intake was associated with an 8% higher risk of overall mortality.

Conversely, intake of high amounts of unsaturated fats—both polyunsaturated and monounsaturated—was associated with between 11% and 19% lower overall mortality compared with the same number of calories from carbohydrates. Among the polyunsaturated fats, both omega-6, found in most plant oils, and omega-3 fatty acids, found in fish and soy and canola oils, were associated with lower risk of premature death.

Is Saturated Fat Healthy ?

Consuming high amounts of saturated fats linked to increased heart disease risk ! ², ³, ⁴, ⁵

In a new study appearing online in the Journal of the American College of Cardiology, Dr. Frank Hu and colleagues found that people who replace saturated fat (primarily found in meats and dairy foods) with refined carbohydrates do not lower their risk of heart disease, whereas those who replace saturated fats with unsaturated fats or whole grains lower their heart disease risk ⁶.

Previous studies have shown that individual saturated fatty acids have different effects on blood lipids, but little is known about associations between individual saturated fatty acid intake and coronary heart disease risk. However, in a study that appeared online on 23rd November 2016, in The British Medical Journal ⁴⁰, where the researchers analyzed data from 73,147 women involved in the Nurses’ Health Study between 1984 and 2012, and 42,635 men who were in the Health Professionals Follow-up Study between 1986 and 2010. Participants reported their diet and health status on questionnaires completed every four years. The study found that a higher intake of the most commonly consumed major saturated fatty acids—lauric acid, myristic acid, palmitic acid, and stearic acid—was associated with a 18% increased relative risk of coronary heart disease ⁴⁰. This study dispels the notion that ‘butter is good’, said Dr. Hu the study co-author. Dr. Hu added, “individual saturated fatty acids share the same food sources, such as red meat, dairy, butter, lard, and palm oil. Therefore it is impractical to differentiate the types of saturated fatty acids in making dietary recommendations, an idea that some researchers have put forth. Instead, it is healthier to replace these fatty acids with unsaturated fats from vegetable oils, nuts, seeds, and seafood as well as high quality carbohydrates” ⁴⁰. “Replacing sources of saturated fat in our diets with unsaturated fats is one of the easiest ways to reduce our risk of heart disease,” said Walter Willett, a co-author and professor of epidemiology and nutrition.

Replacing just 1% of daily consumption of these fatty acids with equivalent calories from polyunsaturated fats, whole grain carbohydrates, or plant proteins, was estimated to reduce relative coronary heart disease risk by 6%-8%. Replacing palmitic acid—found in palm oil, meat, and dairy fat—was associated with the strongest risk reduction.

Figure 6. Dietary Fats and Heart Disease Risk

These findings support current dietary recommendations to replace saturated fat and trans-fat with unsaturated fat.

• Scientists concluded that saturated fat should be no more than 5 percent to 6 percent of daily calories. So, for a diet of 2,000 calories a day, that would mean no more than 120 of them should come from saturated fats. That’s about 13 grams of saturated fats a day ⁸.

There’s a lot of conflicting information about saturated fats. Should you eat them or not ?

Saturated fats are bad for your health in several ways:

• Heart disease risk. Your body needs healthy fats for energy and other functions. But too much saturated fat can cause cholesterol to build up in your arteries (blood vessels). Saturated fats raise your LDL, or bad, cholesterol. High LDL cholesterol increases your risk for heart disease and stroke.

• Weight gain. Many high-fat foods such as pizza, baked goods, and fried foods have a lot of saturated fat. Eating too much fat can cause you to gain weight. All fats contain 9 calories per gram of fat. This is more than twice the amount found in carbohydrates and protein.

Cutting out high-fat foods can help keep your weight in check and keep your heart healthy. Staying at a healthy weight can reduce your risk of diabetes, heart disease, and other health problems.

The most recent American Heart Association and American College of Cardiology advisory ⁸, reaffirms that longstanding advice. Here are some of the scientific highlights:

• Randomized controlled trials that lowered intake of dietary saturated fat and replaced it with polyunsaturated vegetable oil reduced cardiovascular disease by about 30 percent – similar to results achieved by some cholesterol-lowering drugs known as statins ⁴¹.

• Prospective observational studies in many populations showed that a lower intake of saturated fat with a higher intake of polyunsaturated and monounsaturated fat is associated with lower rates of cardiovascular disease ¹⁷.

• Several studies found that coconut oil – which is predominantly saturated fat but has been widely touted recently as healthy – raised LDL cholesterol to the same degree as other saturated fats found in butter, beef fat, ghee and palm oil.

• Replacing saturated fat with mostly refined carbohydrate and sugars does not lower rates of heart disease, but replacing these fats with whole grains is associated with lower rates. This indicates that saturated fat and refined carbohydrate are equally bad relative to heart disease risk.

Saturated fats are found in all animal foods, and some plant sources.

The following foods are high in saturated fats. Many of them are also low in nutrients and have extra calories from sugar:

• Baked goods (cake, doughnuts, Danish)
• Fried foods (fried chicken, fried seafood, French fries)
• Fatty or processed meats (bacon, sausage, chicken with skin, cheeseburger, steak)
• Whole-fat dairy products (butter, ice cream, pudding, cheese, whole milk)
• Solid fats such as coconut oil, palm, and palm kernel oils (found in packaged foods)

Here are some examples of popular food items with the saturated fat content in a typical serving:

• 12 ounces (oz), or 340 g, steak — 20 g
• 12 oz (340 g) cream of mushroom soup — 22 g
• Cheeseburger — 10 g
• Vanilla shake — 8 g
• 1 tablespoon (15 mL) butter — 7 g

It is fine to treat yourself to these types of foods once in a while. But, it is best to limit how often you eat them and limit portion sizes when you do.

What’s my daily limit for foods with saturated fats ?

The American Heart Association recommends aiming for a dietary pattern that achieves 5% to 6% of calories from saturated fat.

For example, if you need about 2,000 calories a day, no more than 120 of them should come from saturated fats.

That’s about 13 grams of saturated fats a day.

How to eat less saturated and trans fats

The American Heart Association ⁴² recommends that adults who would benefit from lowering LDL cholesterol reduce their intake of trans fat and limit their consumption of saturated fat to 5 to 6 percent of total calories.

Are all foods labeled “trans fat-free” healthy foods ?

Not necessarily. Foods labeled “0 trans fat” or cooked with “trans fat-free” oils may contain a lot of saturated fats, which raise your bad cholesterol levels. “Trans fat-free” foods may also be unhealthy in terms of their general nutrient content. For example, baked goods also tend to be high in added sugars and low in nutrients.

Here are some ways to eat less saturated and trans fats:

• Eat a dietary pattern that emphasizes fruits, vegetables, whole grains, low-fat dairy products, poultry, fish and nuts. Also limit red meat and sugary foods and beverages.
• Use naturally occurring unhydrogenated vegetable oils such as canola, safflower, sunflower or olive oil most often.
• Look for processed foods made with unhydrogenated oil rather than partially hydrogenated or hydrogenated vegetable oils or saturated fat.
• Use soft margarine as a substitute for butter, and choose soft margarines (liquid or tub varieties) over harder stick forms. Look for “0 g trans fat” on the Nutrition Facts label.
• Doughnuts, cookies, crackers, muffins, pies and cakes are examples of foods high in trans fat. Don’t eat them often.
• Limit commercially fried foods and baked goods made with shortening or partially hydrogenated vegetable oils. These foods very high in fat, and it’s likely to be trans at.
• Limit fried fast food. Commercial shortening and deep-frying fats are still made by hydrogenation and contain saturated fat and trans fat.

What are alternatives to replace saturated fats in the foods you eat ?

To get the nutrients you need, eat a dietary pattern that emphasizes:

• fruits, vegetables,
• whole grains,
• low-fat dairy products,
• poultry, fish and nuts,
• while limiting red meat and sugary foods and beverages.

Choose lean meats and poultry without skin and prepare them without added saturated and trans fat.

You should replace foods high in saturated fats with foods high in monounsaturated and/or polyunsaturated fats. This means eating foods made with liquid vegetable oil but not tropical oils. It also means eating fish and nuts. You also might try to replace some of the meat you eat with beans or legumes.

3) Bad Fats (Trans Fat or Hydrogenated Oils):

The worst type of dietary fat is the kind known as trans fat. The right amount of trans fats is zero !   These fats have no nutritional value and we know for certain they are bad for heart health. Trans fats increase LDL cholesterol and triglyceride levels while reducing levels of HDL cholesterol. The trans fats also known as hydrogenated oils because the trans fats come from vegetable oils that were chemically modified so they are solid like butter. The solidifying process – called hydrogenation – that is used to turn healthy oils into solids and to prevent them from becoming rancid. When vegetable oil is heated in the presence of hydrogen and a heavy-metal catalyst such as palladium, hydrogen atoms are added to the carbon chain. This turns oils into solids. It also makes healthy vegetable oils more like not-so-healthy saturated fats. On food label ingredient lists, this manufactured substance is typically listed as “partially hydrogenated oil” in order to extend the shelf life of food, but it also turns polyunsaturated oils into a kind of man-made cholesterol. Trans fats can increase your level of “bad” LDL cholesterol and may increase your risk of heart disease. What’s more, these man-made fats are taken up by the body much easier than are omega-3s. So trans fatty acids not only harm your health, they also block the absorption of healthy fats.

Because these oils don’t spoil as quickly as butter, they are used in most packaged cookies, chips, crackers and other baked goods sold in the supermarket, as well as in margarines. Trans Fat (Hydrogenated Oils) are found in most processed food, including margarine, potato chips, baked goods, cookies, pastries to fast-food French fries, etc. They are toxic, blocking absorption of essential fatty acids and eating foods rich in trans fats increases the amount of harmful LDL cholesterol in the bloodstream and reduces the amount of beneficial HDL cholesterol. Trans fats create inflammation, which is linked to heart disease, stroke, diabetes, and other chronic conditions. They contribute to insulin resistance, which increases the risk of developing type 2 diabetes. Research from the Harvard School of Public Health and elsewhere indicates that trans fats can harm health in even small amounts: for every 2% of calories from trans fat consumed daily, the risk of heart disease rises by 23%.

The American Heart Association recommends limiting your trans fat daily consumption to less than 1 percent.

Trans fats have no known health benefits and that there is no safe level of consumption. Recently, the FDA banned trans fats from the U.S. food supply. The phasing-out process is expected to take three years. The encouraging news is that many major food suppliers and restaurants have already substituted healthier fats for trans fats. Today, these mainly man-made fats are rapidly fading from the food supply.

The consumption of trans fats has been directly linked to an increase in coronary heart disease. Trans fats appear to have a detrimental effect on serum lipids by increasing LDL “bad” cholesterol and triglyceride levels, and reducing high-density (HDL “good”) lipoprotein cholesterol levels ⁴³, ⁴⁴, ⁴⁵, ⁴⁶, ⁴⁷. Studies have shown that substituting 2 percent of total energy intake with trans-fatty acids is associated with a 14 to 36 percent increase in the incidence of coronary artery disease (Table 2) ⁴⁸, ⁴⁹, ⁵⁰, ⁵¹. Observational data from the Nurses’ Health Study suggests that replacing 5 percent of energy from saturated fat with energy from unsaturated fats could reduce the risk of coronary heart disease by 42 percent; however, replacing only 2 percent of energy from trans fats with energy from non-hydrogenated, unsaturated fats could reduce the risk of coronary heart disease by 53 percent ⁴⁸.

Table 2. Trans Fat Consumption and Coronary Heart Disease

Study	Number of patients	Years of follow-up	Relative risk of coronary heart disease with trans-fat consumption*
Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study 49	21,930 men who smoke	6.1	1.14
Zutphen Elderly Study 47	667 men	10	1.28
Health Professionals Follow-up Study 50	43,757 men	6	1.36
Nurses’ Health Study 48	80,082 women	14	1.33

---

[Source ⁵²]

How Much Good Fats Do You Really Need ?

In 1999, the International Society for the Study of Fatty Acids and Lipids agreed upon a recommendation table on daily intake of fatty acids as a foundation for further discussions ¹. Polyunsaturated fatty acids (PUFAs) with 18 carbon (C18) atoms such as linoleic (18:2 ω-6), and α-linolenic (18:3 ω-3) are known as essential fatty acids in human nutrition ⁵³. These fatty acids, although regarded as an indispensable component for cell structure and development and function, cannot be synthesized by the human body. Nutritionists recommend a balanced lipid intake corresponding to a total amount of fats equal to 25 to 30% of total calories with a ratio in fatty acids as follows: 1-Saturates (6–8%), 2-Monounsaturates (12–14%), 3- Polyunsaturates as a ω-6 (6–7%), and 4-Polyunsaturates as a ω-3 (0.5–1.5%) ⁵⁴. The American Heart Association recommends aiming for a dietary pattern that achieves 5% to 6% of calories from saturated fat ⁵⁵. Saturated fatty acids increase plasma cholesterol level and acts as “promoters” of certain cancer development (e.g., colon, breast, and perhaps uterus and prostate).

Adequate intake levels for adults were specified with respect to α-linolenic acid (ALA or Omega-3 fatty acid 18:3ω-3), eicosapentaenoic acid (EPA or Long Chain Omega-3 fatty acid 20:5ω-3), docosahexaenoic acid (DHA or Long Chain Omega-3 fatty acid 22:6ω-3), as well as upper limits for linoleic acid (LA or Omega-6 fatty acids), trans-fatty acids, and saturated, given as % of total energy content, respectively. Given a total fat range from 15% to 40% of total energy content, there is no precise value (i.e., % of total energy content in the form of MUFA) was given by the panel ⁵⁶. According to the Joint FAO/WHO Expert Consultation Committee, MUFA intakes should be determined by calculating the difference: MUFA (% of total energy content) = total fat (% of total energy content) − SFA (% of total energy content) − PUFA (% of total energy content) − TFA (% of total energy content). Accordingly, MUFA intakes (% of total energy content) will range with respect to the total fat and fatty acid composition of the diet ⁵⁷.

The debate continues on the optimal dietary fatty acid composition, but the evidence supporting Monounsaturated Fatty Acid (MUFA) as the healthy dietary fatty acid is weak. Even when considering the food source of MUFA (plant vs animal), there is little evidence to support recommendations to increase dietary MUFA for coronary heart disease prevention. However, since no detrimental effects of MUFA-rich diets were reported in the literature to date, there is no evidence speaking against the consideration of MUFAs in dietary guidelines. Further studies dealing with long-term effects of MUFA on biomarkers of obesity, diabetes, and cardiovascular diseases as well as clinical endpoints are needed to clarify the potential benefits of MUFA-rich diets in primary and secondary prevention.

On the other hand, increasing dietary Polyunsaturated Fatty Acid (PUFA) consistently appears to provide benefit. A considerably larger number of meta-analyses explored the effects of Polyunsaturated Fatty Acids (PUFAs) on maintenance or reduction of body weight as well as biomarkers of impaired glucose metabolism or cardiovascular disease or coronary heart disease than there are systematic reviews and meta-analyses dealing with the corresponding impact of Monounsaturated Fatty Acids (MUFAs). Consequently, the international recommendations for Polyunsaturated Fatty Acid (PUFA) are more consistent than those for MUFA, averaging a value of 10% of total energy content for healthy persons for the most part. If MUFA recommendations are given at all, they vary between 12% and 25% of total energy content, equaling a remarkable range of ~30–70 g/day for a 2.500 kcal-diet. Prestigious authorities and organizations such as the National Institute of Medicine, the EFSA, the USDA and the ADA do not provide specific recommendation for MUFAs either for healthy people or for patients in need of diabetic or cardiovascular management.

Most of us get too much fat, and too much unhealthy fat. Most experts recommend that we get 30% of our calories from good fat, although we can survive fine on as little as 20%, even 10%. If you’re like most of us, you’re getting plenty of fat – most Americans consume about 40% of their calories from fats in meat, butter, cheese, baked goods, etc.

To make the switch to heart-healthy fats, start by avoiding the truly unhealthy fats – trans fatty acids. These trans fats come from vegetable oils that were chemically modified so they are solid like butter. Because these oils don’t spoil as quickly as butter, they are used in most packaged cookies, chips, crackers and other baked goods sold in the supermarket, as well as in margarines.

Summary

• Decreased saturated fatty acid intake decreases blood total cholesterol and LDL cholesterol concentrations.
• Replacement of saturated fatty acids with polyunsaturated and/or monounsaturated fatty acids decreases blood total cholesterol and LDL cholesterol concentrations.
• Most of us eat too much fat, and too much unhealthy fat. Most experts recommend that we get 30% of our calories from good fat, although we can survive fine on as little as 20%, even 10%. If you’re like most of us, you’re getting plenty of fat – most Americans consume about 40% of their calories from fats in meat, butter, cheese, baked goods, etc.

Conclusion

Different types of dietary fat had different associations with mortality, the researchers found. Trans fats—on their way to being largely phased out of food—had the most significant adverse impact on health. Every 2% higher intake of trans fat was associated with a 16% higher chance of premature death during the study period. Higher consumption of saturated fats was also linked with greater mortality risk. When compared with the same number of calories from carbohydrate, every 5% increase in saturated fat intake was associated with an 8% higher risk of overall mortality.

Conversely, intake of high amounts of unsaturated fats—both polyunsaturated and monounsaturated—was associated with between 11% and 19% lower overall mortality compared with the same number of calories from carbohydrates. Among the polyunsaturated fats, both omega-6, found in most plant oils, and omega-3 fatty acids, found in fish and soy and canola oils, were associated with lower risk of premature death.

Because fat is an essential nutrient to give your body energy, help your body absorb some nutrients and produce important hormones and to support cell growth. Eating foods with fat is definitely part of a healthy diet. A healthy diet can include the foods you love. You don’t have to avoid treats entirely, but you do need to eat less of foods that are low in nutrition and high in calories.

Just remember to choose foods that provide good fats (monounsaturated and polyunsaturated fats) and balance the amount of calories you eat from all foods with the amount of calories you burn. Whether it is olive oil, ghee, butter or coconut oil — they are all 100 percent fat. All fat have calories.

All fats, whether good or bad, no matter how good the oil sounds — remember that it is still a fat, with 120 calories per tablespoon. Consuming a high fat diet may lead to becoming overweight and that is not healthy !

Aim to eat a dietary pattern that emphasizes intake of vegetables, fruits, and whole grains; includes low-fat dairy products, poultry, fish, legumes, non-tropical vegetable oils and nuts; and limits intake of sodium, sweets, sugar sweetened beverages and red meats. Doing so means that your diet will be low in both saturated fats and trans fats.

While you switch to a heart-healthy diet you may need to keep tabs on your calorie intake for a while.

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