Fats (Lipids)

Summary:

The human body requires fats for a variety of functions, however some types of fats we need can be created partially from carbohydrates. Dietary fat can come in the form of saturated fats (often from meats and dairy) or as unsaturated fats (mono-unsaturated and poly unsaturated).

Your body needs some saturated fats. However, the current recommended limit for saturated fat is between 6% and 10% of total calories. Fat has 9 calories per gram; eating 2000 calories per day means only about 22 grams or less of saturated fat. Eating high levels of saturated fats raises total cholesterol and has been linked to cardiovascular disease, inflammation disorders and dementia.

Studies indicate that consuming monounsaturated and poly-unsaturated fats, particularly when they displace high levels of saturated fats, have health benefits. These benefits may include:

Lowering bad cholesterol;
Raising good cholesterol;
Lower triglycerides;
Reducing the risk of heart and blood vessel diseases.
Helping control blood sugar levels.

Good Fats: The most important good fat is Omega-3 in part since most Americans consume too little of it. Omega-9 (monounsaturated fats) and Omega-6 are also good fats especially when consumed to displace high levels of saturated fats.

Bad Fats: The worst fats are trans fats but these are now largely banned in the US. In the past they existed primarily from processing plant oils to create partially hydrogenated oils. While your body needs some saturated fats, the average American consumes too many saturated fats and hence they are here on my bad fats list.

Background:

In the human body, fats are necessary for:

creating certain hormones,
metabolic regulation,
storing fat-soluble vitamins,
creation of cell membranes and cellular structures;
brain health;
acting as messengers to help proteins do their jobs.

Fat cells (adipose tissues) are also important for insulation and cushioning of organs and as a store of energy.

When your body digests dietary fat it is broken down into fatty acids that may be transported initially via the lymphatic system but eventually via the blood. These fatty acids may be in the form of chylomicros or smaller lipids of varying density that often contain triglycerides and cholesterol. These molecules are eventually absorbed by your cells.

For some types of fats, your body can create some of those needed fats from carbohydrates. For example, your body makes about 80% of the cholesterol you need from carbohydrates. That is, only 20% is needed from dietary fat (about one to one-and-a-half egg yolks a day).

The American Heart Association recommends the following bounds:

total cholesterol < 200 mg/dL;
LDL < 100 mg/dL;
triglycerides <150 mg/dL.
HDL is recommended at 60 mg/DL or higher.
Total fat: 20% to 35% of total calories.

Categories of Dietary Fats & Their Health Characteristics (This section relies heavily upon material from the Mayo Clinic – their descriptions are generally simple but science-based). Dietary fat: Know which to choose - Mayo Clinic:

Most foods have a mix of different kinds of fat. But some have higher levels of saturated fats, and others have higher levels of unsaturated fats. Key differences in fats include the following:

Saturated fats. Saturated fats have all carbon bonds “saturated” with hydrogen atoms and are usually solid at room temperature. The most common sources of saturated fats are meats and dairy products.
Unsaturated fats. Unsaturated fats are usually liquid at room temperature. Vegetable oils, nuts and fish have mostly unsaturated fats. There are two types of unsaturated fats: monounsaturated and polyunsaturated.

Saturated fats in food

The Dietary Guidelines for Americans suggest that less than 10% of calories a day should be from saturated fats (about 22 grams at 2,000 calories a day). This recommendation was retained in the new 2025-2030 Dietary Guidelines. The American Heart Association suggests a goal of 5% to 6% of daily calories from saturated fats.

Foods high in saturated fats include:

Lard; Foods baked or fried using saturated fats.
Meats: beef, lamb, pork as well as poultry, especially with skin on.
Dairy products like butter and cream; Whole or 2% milk.
Whole-milk cheese or yogurt.
Oils from coconuts, palm fruits, or palm kernels.

Saturated fats can add up quickly in foods that combine ingredients. In U.S. diets, the most common sources of saturated fats are sandwiches, burgers, tacos and burritos — foods that usually combine meat and dairy products. Baked goods with butter, full-fat ice cream and other desserts are also common sources of saturated fats.

Low-density lipoprotein (LDL) is referred to as "bad" cholesterol. High-density lipoprotein (HDL) is referred to as "good" cholesterol.” Saturated fats raise the levels of both.

A high level of bad cholesterol in the bloodstream increases the risk of heart and blood vessel diseases. There is some evidence that saturated fats and high cholesterol levels may be linked to an increased risk of Alzheimer's disease or other diseases that cause dementia.

Omega-X. Another characteristic of some fats is having a double carbon bond at one point in the long carbon chain. The double carbon bond is a weak spot. Omega-X is the typical description where X is the number of carbon atoms from the terminal methyl group at which the double bond occurs. For example, Omega-3 (a good fat) has a double bond occurring at the 3rd carbon atom from the terminal methyl group, and your body can more easily peel off this 3-carbon segment.

Monounsaturated fats in food (often Omega-9)

Monounsaturated fats are found in many foods, including red meats and dairy products. About half the fats in these foods are saturated and half monounsaturated.

Many plants and plant oils are high in monounsaturated fats but low in saturated fats. These include:

Oils from olives, peanuts, canola seeds, safflower seeds, and sunflower seeds.
Avocadoes.
Pumpkin seeds; Sesame seeds.
Almonds; Cashews; Peanuts and peanut butter; and Pecans.

Monounsaturated fats from plants are often in the Omega-9 category. Eating these fats (particularly extra virgin olive oil and tree nuts) to displace high levels of saturate fats may lower bad cholesterol, raise good cholesterol and lower triglycerides. This may also improve the control of blood sugar levels.

Triglycerides are fat cells that circulate in the bloodstream and are stored in the body's fat cells. A high level of triglycerides in the blood increases the risk of diseases of the heart and blood vessels.

Polyunsaturated fats in food

The two categories of polyunsaturated fats are omega-6 fatty acids and omega-3 fatty acids.

Omega-6. Sources of omega-6 fatty acids include: Canola Oil, Corn oil; Cottonseed oil; Peanut oil; Soybean oil; and Sunflower oil.

Benefits of a diet high in omega-6 fatty acids, especially when they replace saturated fats, may be linked to:

Lower bad cholesterol; Higher good cholesterol.
Lower triglycerides.
Better blood sugar control.

Omega-3. Omega-3 fatty acids are essential (they can’t readily be synthesized and must be obtained from food). They are important for:

lowering triglycerides,
heart health,
brain and eye health,
other benefits.

Sources of omega-3 fatty acids include:

Oily fish such as salmon, anchovies, mackerel, herring, sardines and tuna.
Oils from canola seeds, soybeans, walnuts and flaxseed.
Soybeans; Chia seeds; Flaxseed; Walnuts.

Of the seed oils, canola is inexpensive and has the highest proportion of Omega 3 fatty acids.

Trans fats in food

Trans fats are a type of fat that raises bad cholesterol and lowers good cholesterol. There are very small amounts of naturally occurring trans fat in meats and dairy from grazing animals, such as cows, sheep and goats.

But most trans fats were in plant oils that have been chemically changed to be a solid fat. These are called partially hydrogenated oils. At one time, trans fat oils were thought to be a healthy choice to replace saturated fats. They also were inexpensive with a long shelf life.

The U.S. Food and Drug Administration determined that artificially created trans fats are "no longer recognized as safe" in foods. They generally are no longer used in U.S. food production (except in small quantities). They may still be used in other countries.

Seed Oils and Omega 3/Omega 6

There are claims that seed oils are harmful to your health. This sometimes arises in discussions about the so-called “hateful 8” – the 8 seed oils most commonly used in production of highly refined/processed foods.

There were two types of shortcomings with the early examinations of seed oils. First, these studies did not attempt to isolate the effect of seed oils separate from the effects of highly refined foods (which are bad for your health). Second, seed oils were used to create partially hydrogenated vegetable oils – the most common form of Trans Fats which were often used in production of highly refined/processed foods. Virtually everyone now agrees that trans fats are bad for your health being associated with increased risk of diabetes, cardio vascular disease and death. One cannot properly extrapolate from the health effects of trans fats to the seed oils which have not been hydrogenated.

Seed oils tend to have a relatively high proportion of Omega 6 fatty acids. Because of early flawed studies of seed oils, there was a focus on the ratio of Omega 3/Omega 6 - suggesting the higher the better. Increasing this ratio could be achieved by increasing Omega 3 and/or decreasing Omega 6. Virtually everyone now agrees that most Americans need to consume more Omega 3 from oily fishes, seeds and nuts. However, modern nutritional research indicates that Omega 6 poly unsaturated fatty acids (n-6 series) are also important for your health.

Consider two recent studies.

Dietary Fatty Acids and Inflammation: Focus on the n-6 Series - PMC Abstract: “… we discuss the most recent evidence of their (n-6 fatty acids) role(s) in human health and prognosis, and we conclude that adequate intakes of n-6 fatty acids are associated with better cardiovascular health and child development.

Dietary Fats in Relation to Total and Cause-Specific Mortality in a Prospective Cohort of 521 120 Individuals With 16 Years of Follow-Up | Circulation Research

Abstract: “Isocaloric replacement of SFA (saturated fatty acids) with linoleic acid (2%) [found in Omega 6 sources] was associated with lower total (8%), Cardio Vascular Disease (6%), cancer (8%), respiratory disease (11%), and diabetes mellitus (9%) mortality.”

Conclusion: “Dietary intake of marine omega-3 PUFAs and replacing Saturated Fatty Acids with plant MUFAs or linoleic acid [Omega 6] were associated with lower total, Coronary Vascular Disease, and certain cause-specific mortality.”

Therefore, Omega 3 and Omega 6 fatty acids are both good for you.

That said, most Americans still need to increase their Omega 3 intake. The table at the link below the plant oils sources with the highest to lowest proportion of Omega 3. Palm Oil is one of the oils I suggest you avoid (low Omega 3 and high saturated fat). Other than flaxseed oils, Canola oil has one of the highest proportions of Omega 3. Olive oil and Avocado oil have health benefits besides containing Omega 3.

Omega 3 to 6 Fat Ratios of All Plant Oils (TABLE)

Saturated Fats: Staying below the 10% of calories guideline

While the new (and the old) US Dietary Guidelines suggests keeping your saturated fat under 10% of your calories, the American Heart Association has, for years, recommended 5% to 6% as a reference point.

With a 2000 calorie a day diet, 10% saturated fat would mean 200 calories from saturated fat. Since fat is 9 calories per gram this is only 22.2 grams. It is easy to have your choices “sneak up” on the 10% of calories. Below are foods that are high in saturated fats. These are all USDA values.