BBC: Which cooking oil is the healthiest?

Oils are all packed with fat and calories, but their chemistry – and effect on our health – can be very different.

By Jessica Brown5th September 2020

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Cooking oils are a kitchen staple. But there’s a lot of conflicting information regarding how healthy each of them are. With so many on the shelves – from coconut to olive, vegetable to canola, avocado to rapeseed oil – how do we know which ones to use, and if we should be avoiding any altogether?

Oils used for cooking tend to get their name from the nut, seeds, fruits, plants or cereals they’re extracted from, either by methods of crushing, pressing, or processing. They’re characterised by their high fat content, including saturated fat, monounsaturated and polyunsaturated fatty acids.

In recent years, coconut oil, which is around 90% saturated fat, has become the latest trendy “superfood”. It’s been hailed as a superfood (including that it's less likely to be stored in the body as fat and more likely to be expended as energy) – but one Harvard University epidemiologist calls it “pure poison”.

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Consuming too much saturated fat – more than 20g for women and 30g for men per day, according to UK guidelines – makes the body produce cholesterol in our bodies that increases the risk of heart disease.

All fat molecules are made of chains of fatty acids, which are either held together with single bonds (saturated) or double bonds (unsaturated). There are three types of fatty acids: short, medium and long chain. Short and medium chain fatty acids are absorbed directly into the bloodstream and used for energy, but long chain fatty acids are transported to the liver, which raises blood cholesterol levels.

“Coconut oil enjoyed popularity three or four years ago, when there were claims it had a special effect,” says Alice Lichtenstein, Gershoff professor of nutrition science and policy at Tufts University in Massachusetts, US.

Vegetable oils usually contain differing amounts of saturated fat, monounsaturated and polyunsaturated fatty acids (Credit: Getty Images)

“But when you look at studies that compared it with other oils, the results showed it’s high in saturated fat, and no clinical trial supported any initial claims.”

Most randomised controlled trials show that coconut oil increases levels of harmful cholesterol low, density lipoprotein (LDL), which is linked with heart disease and stroke, but it also raises beneficial cholesterol, high density lipoprotein (HDL), which carries LDL away from the bloodstream.

One explanation as to why a food so high in saturated fat could increase HDL cholesterol is because it contains a relatively high amount of lauric acid, which has been found to raise levels of HDL in the blood far more than it does LDL .

Experts advise opting for an oil lower in saturated fat, and higher in other types of fats that are healthier in moderation

But Taylor Wallace, an adjunct professor in the Department of Nutrition and Food Studies at George Mason University in Virginia, argues lauric acid is not as healthy as some claims suggest.  It is categorised as a C12 fatty acid, meaning it has 12 carbon atoms, and that puts it at the limit of the definition of a medium chain fatty acid.

“C12s are like long chain fatty acids that got categorised into medium chain,” says Wallace. “About 70% of C12s act as long chain fatty acids, which are transported to the liver.” Longer chain fatty acids are more likely to be stored in the liver as fat and could, over time,  cause health issues such as nonalcoholic fatty liver disease.

Instead, experts advise opting for an oil lower in saturated fat, and higher in other types of fats that are healthier in moderation. Polyunsaturated fat, including omega 3 and omega 6, and monounsaturated fat have been found to lower cholesterol levels and provide essential fatty acids and vitamins. They’re found in many different types of vegetable oils, although the exact amount depends both on the plant and the technology process used during their production.

Replacing saturated fats such as butter with olive oil could lead to reduced risk of developing heart disease (Credit: Getty Images)

“Most studies indicate that foods higher in monounsaturated and polyunsaturated fats are associated with lower risk of cardiovascular disease,” says Lichtenstein. “It’s recommended we replace sources of unsaturated fat with polyunsaturated fat, primarily plant-based oils, and nuts and seeds,” she says.

One observational study associated replacing saturated fat with olive oil, for example, with a  lower risk of heart disease. Substituting butter, margarine, mayonnaise or dairy fat olive oil reduced the risk by 5 to 7%.

Marta Guasch-Ferre, author of the study and a research scientist Harvard University’s TH Chan School of Public Health’s nutrition department in Boston, analysed the health and diets of more than 100,000 people over 24 years, and found that those with higher intake of all types of olive oil had a 15% lower risk of heart disease.

Olive oil, which is made by crushing olives and separating the oil from their pulp, is renowned for being the healthiest of plant oils

Olive oil’s health benefits can partly be attributed to its monounsaturated fatty acids, which contain vitamins and minerals, and polyphenols, micronutrients derived from plants.

“But it’s not just that you’re adding olive oil into the diet, but that olive oil is substituting other unhealthier fats,” says Guasch-Ferre.

Olive oil, which is made by crushing olives and separating the oil from their pulp, is renowned for being the healthiest of plant oils. One review of research found olive oil has beneficial effects on gut microbiota and heart disease, and that extra virgin olive oil can be beneficial in preventing cancer and type 2 diabetes.

The smaller short chain and medium chain fatty acids in some vegetable oils are dissolved in the blood rather than being stored in the liver (Credit: Getty Images)

“The monounsaturated fatty acids and compounds found in olive oil help prevent noncommunicable diseases, not through any special mechanisms, but because our body needs them,” says Francisco Barba, professor at the University of Valencia’s preventive medicine and public health department in Spain.

Olive oil is synonymous with the Mediterranean diet, which is high in fruit, vegetables and legumes, and low in saturated fat, and is associated with a reduced risk of heart disease, despite the high fat content.

“What makes the Mediterranean diet different from other types of healthy diets is olive oil,” Guasch-Ferre says. “Most other components – nuts, fruit and vegetables – are parts of numerous diets, including plant-based.”

Some research has found that extra virgin olive oil is associated with the most health benefits

However, some research suggests these health benefits could be partly driven by other components in the diet, rather than olive oil. One review of evidence found that the only benefit of olive oil independent of the Mediterranean diet was its ability to raise levels of beneficial cholesterol HDL.

Researchers reviewed 30 studies where participants’ diets were altered to test the effects of olive oil, and found that the Mediterranean diet led to lower glucose levels and higher LDL compared to the Western diet. Intervening that diet with olive oil, where it had a high polyphenol content, further increased HDL.

However, consuming olive oil by following the Mediterranean diet was associated with improved glucose levels, which is associated with a greater risk of developing type 2 diabetes if it is too high. It also reduced the level of triglycerides, a type of fat in the blood, and LDL cholesterol levels.

These studies tested numerous types of olive oil, but some research has found that extra virgin olive oil is associated with the most health benefits, including a possible lower risk of heart disease.

Experts advise opting for an oil lower in saturated fat, and higher in other types of fats that are healthier in moderation (Credit: Getty Images)

Extra virgin olive oil is rich in antioxidants and vitamin E, and researchers have found that it’s better at protecting against LDL cholesterol than other types of olive oil. Other types of olive oil are processed after the oil is extracted, which causes them to lose some nutritional qualities.

Extra virgin olive oil, however, has a lower smoke point, which means it starts to smoke at a lower temperature, and in recent years there have been concerns that this could release harmful compounds, and that some of its benefits are lost through the heating process.

“Extra virgin olive oil is especially beneficial when it’s not cooked, but even under cooking it has a very high percentage of monosaturated fatty acids,” says Barba.

The message isn’t to add lots of oil because we think it’s good for us, because that’s just adding lots of calories – Alice Lichtenstein

Recent studies have shown that extra virgin olive oil is safe to use for cooking. Researchers carried out a number of experiments monitoring extra virgin olive oil as it cooked at 120C (248F) and (338F) on a pan for different lengths of time. They found that temperature, but not time, had some effect on the polyphenol content in the oil.

In 2011, the European Food Safety Authority concluded that makers of olive oil can say it reduces oxidative stress – an imbalance of free radicals and antioxidants in the body – and protects cells and LDL cholesterol from oxidative damage, which can age cells. The researchers carrying out the experiments found that extra virgin olive oil used for cooking still falls within the guidelines for the health claim.

Lichtenstein argues that olive oil doesn’t have any unique properties aside from what you’d normally expect from an oil high in monounsaturated and polyunsaturated fats. But what is clear is that the evidence supports using this and other vegetable oils instead of saturated fats, but to limit our intake of oil in general.

 “The message isn’t to add lots of oil because we think it’s good for us, because that’s just adding lots of calories,” she says.

 “Once we shift the balance of saturated fat to unsaturated fatty acids, we should then be able to choose the oil we prefer.”

https://www.bbc.com/future/article/20200903-which-cooking-oil-is-the-healthiest

Must Read: DANGERS OF HIGHLY REFINED COOKING OILS

“Vegetable” oil makes you exceedingly vulnerable to cancer. Every mouthful of vegetable oil you consume takes you one step closer to a deadly (and irreversible) outcome. David Gillespie

by Yeong Sek Yee

Highly refined cooking oils (sometimes referred to as “plastic fats”) go through 3 main refining procedures. These are neutralization, bleaching, and deodorization and then the final light golden colour oil is usually called NBD Palm Oil (or Soya, Corn, etc) Nowadays it is just referred to as refined palm (or soya, corn) oil or refined vegetable oil.

Below is a brief description of the 3 procedures in getting the oils out of seeds, nuts, pericarps, etc and onto the supermarket shelves.

NEUTRALIZATION (sometimes referred to as refining):

Once extracted, the oil ‘needs’ to be refined, which involves the treatment of the crude oil with a lye solution to reduce the free fatty acid (FFA) content to 0.05 percent. This is done primarily to prevent spoilage—to help the oil last an eternity on the grocer’s shelf. In addition, other impurities in the oil, such as gums, phosphatides, pigments, and other oxidation products, which would ‘impair’ the taste, odor, shelf life, and other ‘desired’ properties of the oil are likewise removed. This degumming and neutralization process is accomplished by means of phosphoric acid and more lye.

BLEACHING

The now ‘neutral’ oil is mixed with bleaching earth (a type of clay) and activated carbon to give the oil a lighter color. Final purification is accomplished using filters, presses, and polishing filters. After this, the oil is pumped into storage tanks.

DEODORIZATION

All edible oils and fats contain certain compounds that give the particular oil its identifiable taste and smell. In all commercial oils, these compounds are removed to make the oil as neutral tasting as possible. This process is called deodorization, and because of the high temperatures involved, it is extremely damaging to the oil.

Refined, bleached oil from refining is first transferred to a de-aerator operating under a vacuum for removal of any air in the oil. 

The oil then passes through a series of heaters, where the temperature is raised high enough for efficient steam distillation and deodorization—upwards of 200°C (450°F). 

At these temperatures, the fundamental structure of many oils is changed into a different form of fatty acid through a process called isomerization. 

These new forms are not beneficial to the human body. The high heat also causes a small amount of trans fatty acids to be formed. 

Finally, steam is blown through the oil to vaporize those components of the oil that actually give it any lingering odor or taste. The fully deodorized, tasteless, and refined oil then passes through a cooler and polishing filter basket for removal of any fine suspension before being finally pumped to the storage tank.

THE FINAL PRODUCT

What’s left is oil that is virtually colorless, odorless, and tasteless, which can last for years in a bottle with no danger of spoilage. 

On the other hand, it has no connection with the beneficial oil that was originally contained in the seed or nut. 

It is now a ‘plastic fat,’ fundamentally changed in structure, that offers no benefits to the human body—a plastic fat that is actually quite harmful. 

In addition, all of the beneficial phyto-chemicals (such as the lignans, which are an integral part of the oil complex and play a key anti-cancer role) have been removed.

With the chemicals used in the refining process, can you visualize what would happen to your body when you consume refined oils on a regular basis such as fried foods like goreng pisang, fried kueh teow, fried chicken, etc? 

In some cases, the already toxic oils is re-used again and again and sometimes plastic straws, plastic bags are added to the frying oil to make the final product “ crispy” for a longer period.

For cancer patients, we strongly recommend that you use cold-pressed oils (such as coconut, olive, flaxseed, etc) where the oil is extracted without the use of heat or chemicals.

FURTHER REFERENCES:

If you would like to read more about the benefits (or dangers) of fats and oils we recommend the following texts:

FATS THAT HEAL, FATS THAT KILL by Udo Eramus who has a PhD in Nutrition. The book exposes the manufacturing processes that turn healing fats into killing fats and explains the effects of these damaged fats on human health.

TOXIC OIL…WHY VEGETABLE OIL WILL KILL YOU by David Gillespie, a lawyer who decided to research thoroughly on “vegetable oils” after his family was faced with some health issues. His opening statement in the book will stun you:

“Vegetable” oil makes you exceedingly vulnerable to cancer. Every mouthful of vegetable oil you consume takes you one step closer to a deadly (and irreversible) outcome. 

You are eating “vegetable oil” because it is cheaper to make food with oils that are chemically extracted/ refined from plant seeds.

http://www.cacare.com/the-dangers-of-highly-refined-cooking-oils

Saturated, but necessary

Sunday March 2, 2014

BY TAN SHIOW CHIN

Around one-third to half of our fat intake comes from the cooking oil used to cook our foods. – Filepic

Saturated fat is often seen as public enemy number one in the war against cholesterol, but it may be less fearsome than it seems.

COMMON knowledge says that eating saturated fat raises your cholesterol levels. And as we also know, high cholesterol levels are a risk factor for coronary artery disease and stroke.

However, not all saturated fats are created equal.

International Medical University nutrition and dietetics associate professor Dr Tony Ng Kock Wai says that people need to get the record straight about saturated fats.

Fats, he explains, are made up of a glycerol backbone and three fatty acids, which are the components that actually cause concern.

“The fatty acids that raise serum cholesterol are limited to four types. The saturated fatty acid types are lauric acid, myristic acid and palmitic acid.

“So, these three saturated fatty acids raise cholesterol; all the other saturated fatty acids do not.”

In fact, Assoc Prof Ng says that if we were to take away all saturated fats from our diet, and only consumed a diet of proteins, carbohydrates, polyunsaturated fats and monounsaturated fats, we would get sick in a matter of weeks.

“Why? Because we are victims to oxidative stress.

“Unsaturated fats are susceptible to attack by reactive oxygen species. The antioxidants in our body tend to counter this effect, but the bad always wins.

“So, in the end, we grow old, we die of old age, we have chronic diseases. Therefore, we need saturated fats to be in there to balance things. Too much of anything is never good,” he explains.

And then there is the fourth type of fatty acid that raises our cholesterol – trans-fat. This, according to Assoc Prof Ng, is the worst type of fat to have in the diet.

“They are not saturated, but they have the trans configuration. They are really bad because they raise blood lipid levels and they raise lipoprotein(a), which is a risk factor (for cardiovascular disease),” he says.

Trans-fat is deemed so harmful that the United States Food and Drug Administration is moving towards banning the use of partially-hydrogenated vegetable cooking oils, which are the main source of trans-fat in our diets.

Fat fear

The fear of saturated fats started in the early 1950s when American physiologist Dr Ancel Keys reported the results of what came to be known as the Seven Countries Study.

According to Assoc Prof Ng, Dr Keys’ study purportedly showed that the intake of saturated fats was directly related to serum cholesterol levels, and thus, to the increased risk of dying from cardiovascular disease.

“And then came this phobia of saturated fats and cholesterol, and this lasted one generation – 50 years or more,” he says.

“But in fact, we do not have to fear saturated fats or dietary cholesterol.”

He points to a meta-analysis of 21 studies done by Children’s Hospital Oakland Research Institute, California, United States, researcher Dr Patty W. Siri-Tarino and colleagues, looking at the association between saturated fat intake and cardiovascular disease.

According to Assoc Prof Ng, palm oil actually has a neutral effect on serum cholesterol. – YAP CHEE HONG/The Star

Published in the American Journal of Clinical Nutrition in 2010, the comparative study found no association between dietary saturated fat and increased risk of cardiovascular disease.

”Saturated fat intake, in fact, lowered the risk of stroke by some 19%,” says Assoc Prof Ng, adding this is a powerful paper as it is a summary of several clinical trials.

He points out that while saturated fats do raise low-density lipoprotein (LDL, or “bad”) cholesterol, they also raise the high-density lipoprotein (HDL, or “good”) cholesterol.

Conversely, polyunsaturated fats do decrease LDL-cholesterol, but they also decrease HDL-cholesterol.

The key, he says, is to keep to the recommended dietary guidelines of keeping fat consumption to less than 10% of your total daily calorie intake.

“The message is, we do not need to fear dietary cholesterol unless we’re having a very high dietary intake, meaning more than 400mg per day.

“We have to remember that the main source of body cholesterol comes from our liver.

“Our liver manufactures 1,000mg of cholesterol a day, and we need cholesterol or we will die,” he says, adding that cholesterol is essential to many bodily functions.

The effects of palm oil

The main source of fats in our diet comes from the oils we use to cook.

“It forms one-third to half of our dietary fat,” says Assoc Prof Ng. “So, choose your cooking oil wisely, I would say.”

The nutritionist, who spoke on Palm Oil as a Major Fat in the Diet: Nutritional and Health Issues at the 2013 MPOB International Palm Oil Congress in November, shares that palm oil is actually the most stable of the cooking oils available.

This means that it can withstand the very high temperatures of deep frying for longer periods of time, compared to unsaturated vegetable oils, which degrade more easily under similar conditions.

Many people fear to use palm oil, as it contains one of the highest saturated fat content among vegetable oils.

However, Assoc Prof Ng points out that research has shown that palm oil does not exhibit quite the cholesterol-raising effects expected from its high saturated fat content.

In a study in Maastricht, the Netherlands, 40 healthy male volunteers were fed a controlled diet where their usual sources of saturated fat – typically animal fats and partially-hydrogenated vegetable oils – were replaced with palm oil.

The 1992 paper published in the British Journal of Nutrition reported that the participants showed no change in their total cholesterol or LDL-cholesterol levels during the trial.

However, their HDL-cholesterol and apolipoprotein A1 levels had increased, while their apolipoprotein B levels had decreased, providing a protective effect against coronary artery disease.

Meanwhile, a 1997 Chinese study comparing the effects of four diets, enriched with palm oil, soyabean oil, peanut oil and lard respectively, in 120 healthy males, found that the palm oil-enriched diet showed the most decrease in total cholesterol and LDL-cholesterol levels.

The same study, published in the Journal of Nutrition, also compared diets enriched with palm oil and peanut oil, in participants with high cholesterol levels.

Those consuming the palm oil-enriched diet showed significant reduction in their total cholesterol and LDL-cholesterol levels, while no changes were seen in the peanut oil-enriched diet, which approximated the volunteers’ usual intake.

This, Assoc Prof Ng concludes, indicates that palm oil is neutral, i.e. it does not raise cholesterol levels, in healthy humans.

Research has suggested that the reason behind this might be the specific distribution of palmitic acid in the palm oil molecule.

Over 90% of the palmitic acid chains sit in position one and three on the molecule’s glycerol backbone, with only 9% occupying the middle position.

“This unique positioning apparently prevents cholesterol raising in the blood, and this has been demonstrated in rabbits,” he says.

The theory behind this is that pancreatic lipase, which is the main enzyme that helps us digest fats, preferentially cuts off the fatty acid chains at positions one and three.

These palmitic acid chains then form calcium compounds and are excreted in the faeces, resulting in their being less well-absorbed, compared to other fatty acids.

However, the story changes when it comes to overweight, and otherwise, unhealthy people.

In such people, the LDL-cholesterol receptors on their cells, which help capture and clear LDL-cholesterol from the bloodstream, become less active, causing an increase in blood LDL-cholesterol levels.

Another factor, he adds, is genetic. People with a certain type of gene, coding for their apolipoprotein E, are prone to having higher levels of blood LDL-cholesterol.

Such people need to be more wary over the overall fat, as well as saturated fat, content of their diets.

http://www.thestar.com.my/Lifestyle/Health/2014/03/02/Saturated-but-necessary/