Vegetable oil consumption has increased a lot in the past 100 years. Mainstream health professionals tend to think vegetable oils are healthy, but they may actually cause some health problems.
The effects that fatty acids have on health depend on the kind of fatty acids they are, what plants they come from, and how they are processed. Let’s look at the evidence to determine if vegetable oils are bad for your health. Let’s also look at the evidence to determine if seed oils are bad for your health.
How are vegetable oils and seed oils made?
Vegetable oils are oils that are extracted from plants. Vegetable oils are not only used for cooking and baking, but also in processed foods such as salad dressings, margarine, mayonnaise, and cookies.
Some of the most common vegetable oils are soybean oil, sunflower oil, olive oil, and coconut oil. Vegetable oils that have been refined were not available until the 20th century. The technology to extract them became available at that time.
The oils are either extracted from plants using a chemical solvent or an oil mill. Afterwards, they go through a process of purification, refinement, and occasionally chemical alteration. Health-conscious consumers prefer oils that are made by crushing or pressing plants or seeds, rather than those produced using chemicals, because they believe that these methods are healthier.
Edible plant oils are commonly known as vegetable oils. Oil is often extracted from plants by crushing or pressing the plants or their seeds. This process can be done with or without chemical solvents.
Fatty Acids & Oils
Fats are classified based on the number of double bonds in their chemical structure. Saturated fats have no double bonds while unsaturated fats have one or more double bonds. The bonds between different types of fat molecules influence the health effects of those fats. Most of the fats in oils are a type of fat called triglycerides.
Saturated fats: No double bonds (butter, lard, coconut fat)
Monounsaturated: One double bond (Olive oil, avocados)
Polyunsaturated: Multiple double bonds (fish oil, vegetable oils)
Different types of oil contain different proportions of the various types of fat. Seeds and vegetables generally have the most polyunsaturated fats (PUFAs).
PUFAs are defined as polyunsaturated fatty acids. There are two categories of PUFA – omega-6 and omega-3 fatty acids. There are two types of fatty acids that are essential to our diet, and are thus called essential fatty acids. Seed oils that have been refined, such as soybean, corn, and safflower oil, contain a high amount of linoleic acid (LA), which is the main omega-6 PUFA that is found in food.
The Impact of Omega-6 Fatty Acids on Health
Linoleic Acid (LA) is an omega-6 fatty acid that is found in vegetable oils, some nuts, and seeds. It can be beneficial for heart health when eaten in moderation and in place of saturated fats.
Research indicates that consuming more omega-6 fats can slightly lower total cholesterol levels over time, which may help protect against heart disease.
According to a review of 49 randomized controlled trials, increasing your intake of polyunsaturated fatty acids (PUFAs) may help reduce your risk of developing coronary heart disease or having a cardiovascular disease event.
However, each PUFA is processed differently by the body. More recent studies have investigated the effect of omega-6s on cardiovascular disease risk factors, such as inflammation.
Omega-6s from Vegetable and Seed Oils are Especially Susceptible to Oxidation
Vegetable and seed oils are sensitive to heat, light, and oxygen because of both the refinement process and the multiple double bonds found in PUFAs.
When exposed to air, PUFAs are more likely to oxidize than other types of fat or whole food sources of omega-6s like nuts or seeds.
Oxidation of oils leads to
- Undesirable tastes
- Decomposition of nutritional quality
- The production of harmful compounds like free radicals
Oils can become oxidized while they are sitting on your shelf or during the cooking process. They can also oxidize and deteriorate within the body, which result in the formation of harmful free radicals.
If the number of free radicals in the body goes up without a corresponding increase in antioxidants, this will cause oxidative damage to molecules and inflammation. Damaged cells produce more free radicals which then cause more cell damage It’s a vicious cycle.
Since LDLs have cell walls made of PUFAs, they are especially vulnerable to oxidation. The levels of low-density lipoprotein (LDL) in the blood influence the risk of developing heart health complications.
If you consume a lot of polyunsaturated fats from refined seed oils, your low-density lipoproteins will become more susceptible to oxidation and degradation. High levels of LDL particles that have been oxidized are very bad for heart health.
It is recommended by medical professionals to consume refined seed oils in moderation, along with increasing the intake of anti-inflammatory fats rich in antioxidants. This is to protect heart health and to prevent oxidative damage.
Consumption of Vegetable Oils has Increased
Over the past century, the consumption of vegetable oils has increased while the consumption of other fats like butter has decreased. They are labeled “heart-healthy” because they are an alternative to sources of saturated fat.
Polyunsaturated fats are considered heart-healthy because studies have shown that they can help reduce the risk of heart problems, compared to saturated fats.
Some scientists are worried about how much of these oils people are consuming despite their potential health benefits.
The amount of vegetable oils consumed increased a lot in the last century. While some vegetable oils have been linked to health benefits, there are concerns about consuming too much omega-6.
You may Want to Avoid Vegetable Oils High in Omega-6
Some plant oils are actually good for your health. Coconut oil and olive oil are both good options. Consider avoiding the following plant oils due to their high omega-6 contents:
- soybean oil
- corn oil
- cottonseed oil
- sunflower oil
- peanut oil
- sesame oil
- rice bran oil
Both omega-6 and omega-3 fatty acids can’t be produced by your body, meaning you need to include them in your diet.
Over the course of evolution, humans have consumed omega-3 and omega-6 in a specific ratio.
In the past century or so, the ratio of omega-6 to omega-3 fatty acids in the Western diet has shifted dramatically and may be as high as 20:1. Some scientists have suggested that having too much omega-6 fatty acids in relation to omega-3 fatty acids may be linked to chronic inflammation.
Some of the most common Western diseases, such as heart disease, cancer, diabetes, and arthritis, are caused by chronic inflammation.
Studies that observe people’s behavior have found that eating a lot of omega-6 fats is linked with increased risks of obesity, heart disease, arthritis, and inflammatory bowel disease. However, these associations don’t necessarily imply a causal relationship.
Studies that have looked into the effects of consuming omega-6 fats have not found that these fats increase inflammation. Eating a lot of linoleic acid, which is the most common omega-6 fat, doesn’t seem to have any effect on blood levels of inflammatory markers.
There is still more research needed in order to understand the effects that omega-6 fats have on the body.
If you want to avoid omega-6 fats, don’t use oils or margarine that contain them. Olive oil is a healthy cooking oil that is low in omega-6.
Some vegetable oils are high in omega-6 fatty acids. Some scientists believe that consuming too much omega-6 may cause increased inflammation in the body, which could potentially lead to various illnesses.
Saturated, monounsaturated, or polyunsaturated fats differ by the number of double bonds their chemical structures contain:
- Saturated fats: no double bonds
- Monounsaturated fats: one double bond
- Polyunsaturated fats: two or more double bonds
Polyunsaturated fats have a problem with double bonds making them susceptible to oxidation. Fatty acids react with oxygen in the atmosphere, causing them to deteriorate.
The fat you eat isn’t just stored as fat tissue or used for energy – it’s also used to make cell membranes. If you have a lot of polyunsaturated fatty acids in your body, your cell membranes are more likely to be damaged by oxidation.
You have a high level of fatty acids that are easily degraded to form harmful compounds.
Polyunsaturated fats should be eaten in moderation. Eating a variety of healthy fats can help improve your overall health. Saturated fats, monounsaturated fats, and polyunsaturated fats are all beneficial in moderation.
Oils that have high levels of polyunsaturated fats are more likely to become rancid or oxidized, both when they are sitting on the shelf and when they are inside your body.
Commercial vegetable oils may also contain trans fats, which form when the oils go through a process called hydrogenation. Food producers use hydrogenation to harden vegetable oils, making them more like butter at room temperature.
This is why vegetable oils in margarine are usually hydrogenated and contain a lot of trans fats. However, trans-fat-free margarine is becoming increasingly popular.
Although non-hydrogenated vegetable oils may contain some traces of trans fats, they are generally much healthier than their hydrogenated counterparts. A study of vegetable oils in the United States showed that the percentage of trans fats ranged from 0.56% to 4.2%.
Eating foods high in trans fats has been linked to various chronic health problems, like heart disease, obesity, cancer, and diabetes. The presence of hydrogenated oil in a product’s ingredient list is a good indicator that the product contains trans fats. For optimal health, avoid these products.
Trans fat, often found in hydrogenated vegetable oils, has been linked with a range of health issues. They can also be found in some types of margarine, ice cream, and cookies.
The Relationship Between Seed and Vegetable Oils, Inflammation, and Heart Health
Fatty acids serve different functions in the body. Saturated fats are believed by some to cause inflammation, but others (especially omega-3s and monounsaturated fats) seem to have anti-inflammatory qualities.
The researchers found that consuming high amounts of omega-6s from refined seed oils can lead to oxidative stress and chronic low-grade inflammation, which can lead to poor heart health outcomes. This is known as “the oxidized linoleic acid hypothesis”.
Though chronic inflammation contributes to heart disease, there are no controlled studies that have analyzed the effects of omega-6 on heart disease in humans.
There are other dietary factors that contribute to inflammation in addition to high intakes of saturated fat, refined grains, meats, and sugars.
Diets that are high in fat and low in carbohydrates can actually be harmful to your health. These diets are low in many nutrients that are essential for reducing inflammation in the body, including fiber, antioxidants, and omega-3 fatty acids. In other words, it is more effective to focus on improving overall diet than on individual nutrients.
Despite the concerns raised by the oxidation sensitivity of omega-6 PUFAs in seed oils, it is unknown whether or not these oils have a positive or negative effect on heart disease risk factors and other health outcomes. Larger randomized controlled trials are needed in order to determine the effects that seed oils have on heart disease risk factors and other health outcomes.
Choosing the Right Oil
Oils are a common type of ingredient used to prepare many different kinds of recipes. The type of cooking oil you use can have different effects on your health, so it is important to choose the right one.
With so many oil options on the market, it can be difficult to choose the right one for your needs. There are different types of fats in oils that can provide different health benefits.
The U.S. Dietary Guidelines recommend limiting oils high in saturated fats like coconut, palm, palm kernel oils. The Dietary Guidelines recommends limiting saturated fat intake to 10% of calories to reduce the risk of cardiovascular disease.
Choose oils that are high in monounsaturated fats like extra virgin olive oil: Oils high in monounsaturated fats can improve blood cholesterol levels. Extra-virgin olive oil has the lowest rate of oxidation of any cooking oil, and is also a great source of antioxidants. Both of these characteristics can help to reduce inflammation.
You should check the best-by date on oils before purchasing them as they should be used within 30 to 60 days after opening to prevent them from going rancid.
The prevalence of processed vegetable and seed oils in today’s food supply has increased dramatically since 1900.
Seed oils were first thought to be “heart healthy” when studies found that replacing saturated fats (such as butter) with fats high in omega-6 polyunsaturated fats (such as vegetable oils) could reduce the risk of cardiovascular disease.
Despite the potential health benefits of omega-6 polyunsaturated fatty acids, scientists are concerned about the drastic increase in consumption of these oils from refined seed oils over the past century.
The main reason people are avoiding omega-6 seed oils is because they might cause inflammation.