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What is Hydrogenated Oil?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

Oils have been hydrogenated for many decades, to prolong their shelf life and make the oils more stable. Hydrogenated oil is oil in which the essential fatty acids have been converted to a different form chemically, which has several effects. Hydrogenated oil is far more shelf stable, and will not go rancid as quickly as untreated oil. It also has a higher melting point, and is often used in frying and pastries for this reason. When hydrogenated, the chemical structure of the oil is changed, which scientists in the 1990s began to realize could result in negative health effects.

Hydrogenated oil is made by forcing hydrogen gas into oil at high pressure. Both animal and vegetable fats can be and are hydrogenated. In general, the more solid the oil is, the more hydrogenated it is. Two common examples of hydrogenated oil are Crisco and margarine. In the 1990s, it was realized that these products might have deleterious health effects, a tragic irony since they were originally produced and promoted as being healthier than conventional oils.

Margarine is a common type of hydrogenated oil.
Margarine is a common type of hydrogenated oil.

The unstable fatty acids in oils are unsaturated fats, which have been determined to be healthier for consumers, acting to reduce cholesterol in some cases. When hydrogenated oil is made, these healthy fats are converted into a new type of fatty acid, known as a trans fat. Trans fats are not at all good for one's health. In some highly hydrogenated oils like margarine, trans fats can make up almost half of the total fat content.

Olive oil is a good example of a healthy fat.
Olive oil is a good example of a healthy fat.

Trans fatty acids work to increase LDL, or "bad" cholesterol, and they also decrease HDL cholesterol, which is "good" cholesterol. This means that the fats in hydrogenated oil are far more damaging than even saturated fats, which medical professionals have already determined to be harmful. There is also evidence to suggest that trans fatty acids may bioaccumulate in the body, because the digestive system has difficulty figuring out what to do with them. As a result, a diet high in trans fats will result in weight gain.

Hydrogenated oil is a source of unhealthy trans fat.
Hydrogenated oil is a source of unhealthy trans fat.

Consumption of hydrogenated oil has been linked with diabetes, coronary disease, and obesity in a wide number of scientific studies. In the 1990s, many activists began to lobby for clear food labeling, indicating when products contained trans fats. Other activists went further, attempting to ban trans fats because of their detriment to human health. All medical professionals agree that people should limit their consumption of hydrogenated oil to avoid exposure to trans fats, and should eat foods with healthy fats such as nuts, avocados, and olive oil.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a TheHealthBoard researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a TheHealthBoard researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

Discussion Comments


I now know what's causing my cholesterol to be way off. 1/2 the stuff I eat is loaded with hydrogenated oils.


What is non hydrogenated oil?


I have a question. Hydrogenating (saturating) a fat means that there is no longer a double bond, which would mean that there is no longer any cis or trans relationship between any of the H's on the carbons. How is it then, that by saturating a bond, you create a trans fat? This doesn't make sense to me as by saturating a bond there is no longer any kind of cis-trans isomerism of any kind.


@anon296909: You deceptive person you. Tell us, do you want to live 10-20 years like animals do, 40-60 years like people in the 18th/19th centuries, or 70-90 years like humans who reduce their meat intake?


Meat is unhealthy? We've been eating meat before we ever knew about agriculture, which means that your statement is simply illogical. This goes hand in hand with the fact that animals have been eating meat for millions if not hundreds of millions of years such as sharks.

I can say that industrialized meat since the turn of the 19th century has additives hormones and whatnot. This is what leads to terrible health along with no exercise. Sugar is the real cause of all those problems such as obesity, heart attacks and strokes. Now can you eat other things that have protein for muscle building and fat loss? Yes. But in high amounts such as in meat? No. Whole foods are great because they take longer for your body to break down and become sugar keeping your insulin levels regulated. It's all about the sugar.


I eat peanut butter almost every day, and do not want to consume lots of hydrogenated oils.

Fortunately, many companies make natural peanut butter, and you can find it in any grocery store. You just have to stir it before you eat it. Personally, my favorite (flavor wise) is Kroger's crunchy peanut butter.

Just look at the ingredients before you buy. There should only be two: Peanuts and salt. --Andrew


@anon160148: Humans evolved to eat meat. Hence why we are omnivores and why I don't instantly die when I eat a steak. Want proof? Do research.


If you love peanut butter so much, make your own! Or if you can't be bothered, find a reputable health store that makes their own. All that goes into homemade or healthy made peanut butter is peanuts. Kraft is selling a peanut flavored spread.

Any spread that has been made on a processing chain is more than likely very bad for you. Common sense prevails.


Why shouldn't we just start doing our own oils, without machines, all handmade, so everything stays transparent and we know exactly what we ingest. Example: Cold pressed oil out of olives, nuts, avocados, etc. Our industry dependency on everything for life is scary.


Trans fats were shown to cause schizophrenia, psoriasis, heart disease and cancer 30 years ago by Dr. Ralph Holman. It changed my life/longevity but look up how studies show the effects of hydrogenated trans-fats on the body for an excellent and exciting background review on trans lipids in disease. Thank me later after you take it to heart.


Eat natural foods, no artificial sweeteners, no artificial fats. Period. Corn oil causes inflammation, which causes cancer. Corn oil, soybean oil, and canola oil (originally created as an industrial oil) are chemically extracted (Hexane). They put these crap oils in nearly everything we eat now because some government officials decided they know best. Make things from scratch whenever possible, using healthy oils like olive, coconut, peanut, and in small amounts, animal fat.

Our bodies need fat, especially our brains, to function normally. Ever wonder why so many kids suffer from attention deficit disorder these days? And, Charlie dear, you are wrong. It's perfectly fine to eat meat. (Don't listen to Charlie, Lindsey.) People were meant to be carnivores and only started getting fat when the government decided to turn the food pyramid upside down, so that we now consume about as much grain as cattle (the fatted calf?) Too many carbs! One more important point. Don't ever take statins! Your body needs cholesterol. Every cell in your body manufactures cholesterol. Inflammation causes heart attacks and strokes, not cholesterol. Statins will kill you. It's really all about the money! God bless! --Patty


Lindsey says, "there are some natural trace amounts in certain kinds of meats and those are okay, considering they are natural!"...."It is extremely important to buy organic produce and meats."

This is sick and comical, really. But, believe me, I understand! It is hard to see the lies that everyone - our teachers, schools, parents, our government, everyone has told us about food and health. Lindsey, below are the truest things you are going to hear about your diet. Why? Because I don't want to make a profit off you!

Hopefully, no one else who reads what you wrote believes this about animal flesh. Eating rotting animal flesh - especially, but not just limited to all the fat it contains - is the worst thing you can do for your body, on par with heavy smoking and excessive drinking. Worrying about things like margarine - although it is very bad for you - while you still ingest dead animals is like worrying about getting to much sun on the deck of the Titanic.

The number one thing you can do for your diet today? Switch to whole, non-animal foods now. After that, you can start to nit pick (or refine your diet) over hydrogenated oils, trans fat, HLD and LDL, etc.

I worry about these things, I investigate them to eliminate unhealthy things from my body, but I am vegan, so for me it makes sense.

To animal eaters, it makes no sense to worry about trans fat and high fructose corn syrup, etc. What you ingest in these “natural” foods (animal carcass) is much worse for you. It is the cause of all types of cancer and disease. Not to mention the misery, since we torture animals all day, every day to feed the humans that get fat off them. That is to say, humans are not doing it to survive, they are doing it - torturing and eating animals - to get lazy and fat, which is clear all around the US and around the world where meat is a mainstay in the diet.

Also, worrying about organic meats is equally foolish. It is like worrying that the rope used to make your noose is not soft enough on your neck. The organic meat fad is simply a way for the meat industry, which is making and keeping you sick, to capitalize on buzz words and American stupidity. Organic or not, meat is very unhealthy.

Sorry, but these have been the cold hard facts, the truth about your diet, Lindsey! Though you are not alone in your dietary choices today, you are also not alone should you decide to head toward healthy, sustainable, natural whole foods. We are growing, and my diet, the food I eat has never been better. I eat more, enjoy the food more and feel better inside myself, about myself and about this world.

All the best, Charlie


Aww man. Skippy peanut butter has hydrogenated oils in it. How can I get a good peanut butter without it being filled with chemicals?


Here's a revolutionary thought: why not just leave all the chemicals out of our food, the way they were intended, in the form that our bodies were made to accept them? No strange/unpronounceable chemicals in our bodies= no strange/unpronounceable diseases we end up getting? Just a thought.


i felt like going mad. Which oil is good and which is bad for our health? i have become more confused.


Hydrogenated fat is solid like margarine -very bad

partially hydrogenated still liquid oil -still very bad

First option: use 50 percent flax oil and 50 percent extra virgin oil in your life.

Second option: coconut oil.


I used to say that the Mafia found a way to dispose of toxic chemicals, they put it in our foods! Think about it the millions of products and chemicals we can't even pronounce are being put into our foods! Maybe I wasn't so far off after all.


Also to add on, stay away from "enriched" bread, if possible. What that means is, there is a process where all the nutrients are taken out and selected ones are put back in. This normally is in bread and wheat products. Refined is also bad for the same reason.

Partially hydrogenated foods are hard to pass, but important to pass up, because if one eats them that may lead to problems with obesity. Also eat the yolk with the white part of the egg, the yolk helps digest the whites. So for those who enjoy egg yolk, you are in luck. You can actually eat the entire egg, but watch how many eggs you eat a week. Don't eat a lot, but eat enough. I think you get the good cholesterol from eating the entire egg, so not all cholesterol is bad.

I am so hungry but I can't eat food that is instant because it is filled with bad ingredients, such as partially hydrogenated, HFCS, and I just go hungry sometimes because I do not want to add such toxins to my body.

I just graduated CSU and I work nights, therefore eating and preparing food in a hurry is my lifestyle, and I am not such a good cook, so I just starve instead of eating processed foods with ingredients listed above.


I'm sorry, but your whole article is wrong. Trans fats or saturated fats don't harm us by affecting cholesterol. Trans fats harm us because they are inflammatory. They are very unstable and already compromised by processing. There's nothing wrong at all with saturated fats from healthy animals.


The love of money will always be the downfall of a nation. The united states has turned the country into a fat place just to lengthen the shelf life of a product so consumers will have a somewhat fresh item.

I would love to agree with comment #34, but the headline might be telling the truth about what lies inside our butters, cereals, chips, snacks, etc.

I just had a small spoon of peanut butter and midway on the ingredient list was the name hydrogenated vegetable oil. Well I hope temperance will allow me to stop with that butter.


If you look around you will find that there a few areas, primarily the meat and or milk from ruminant animal, that occur naturally.

These are used by the body to manufacture CLA (conjugated linoleic acid) which means the body has a metabolic pathway for it. However, hydrogenated or partially hydrogenated oils are never natural, as they are made by superheating oils and bubbling hydrogen through them.

This changes their chemistry to one that has no beneficial metabolic path. CLA is good for HDL and enhancing metabolism, while hydrogenated or partially hydrogenated oils inhibit HDL and are easily oxidized into plaque which sticks to blood vessel walls.


Lindsey89 you are wrong!

What is the difference between partially hydrogenated oils and fully hydrogenated oils? Hydrogenation is the process by which liquid vegetable oil is turned into solid fat. Partially hydrogenated oils contain trans fats. However, when liquid vegetable oil is fully hydrogenated, almost no trans fats remain.

Full hydrogenation increases the amount of saturated fats, mostly in the form of stearic acid. Stearic acid does not raise levels of LDL (“bad”) cholesterol. This makes

fully hydrogenated fats less harmful than partially hydrogenated fats.


My peanut butter's nutrition label says 0 Trans Fats, but the ingredients list Peanuts, Hydrogenated oil. Now I know why we don't have to refrigerate peanut butter.


I would like to know about cooking sprays what type of fats do cooking sprays go under.


The newest thing out there are these cholesterol-lowering spreads. 0 Trans Fats on the front, but beware! With these "actively cholesterol-lowering" plant stenol esters, you are also eating partially hydrogenated soybean oil - which in turn will raise your bad cholesterol and is most certainly derived from genetically modified soybeans.

Excellent example of selling cheap, unhealthy ingredients for high dollar. Oh yeah, 0 trans fats because the intake per serving is only 0.5 grams, but with 4-5 recommended servings per day you are ingesting 2.5 grams of trans fats, not counting what is in your bagels or your other food!


The reason labels can claim "no trans fat" is because the law suggests that less than .5 grams or less per serving = 0 trans fat, but if the contents contain partially hydrogenated or hydrogenated oils, it does contain trans fat but less than .5 grams per serving.

Keep in mind though, most serving sizes are ridiculous and people tend to eat more, so if you eat two servings of cheetos (which is easy to do) you're actually eating 1 gram of trans fat. Now add that up throughout the day. You always have to be on the look out!


Trans fats are unsaturated fats. Vegetable oils that have been hydrogenated to have more desirable properties, apart from clear negative health effects. They might be listed as partially hydrogenated vegetable oil or something like that. They're mostly phased out over here as far as I know.

I say definitely stay far away from them, and tbh vegetable oils in general. You shouldn't avoid saturated animal fats and also try to consume less omega 6 and more omega 3 fats, as the normal diet has way too much of the former in it. Humans have been eating animal fats for 2 million or so years, only now have we started eating fats/oils from vegetables and such, because it is cheap and convenient.


Could you tell me if (Non Hydrogenated) vegetable oil, is bad for you? is it a cover up for a bad fat? it is in the ingredients of a cake sold by a supermarket. the cake also has rapeseed oil but it is a latter ingredient which is an up and coming good oil, so i have been told.


I logged on to figure out the difference between partially hydro oils and plain hydro oils, apparently they are both bad. But packaging claims make it impossible to figure this out.

i recently bought Kraft cool whip free, and it says on the front, 0grams trans fat, but the third ingredient was hydro oils. Hmm... won't be using kraft foods ever again. i don't like being played a fool.

Bakers and chefs there is organic no trans fat shortening at some super markets. Spectrum Naturals is a good brand.


anon42306, Whole Foods sells an "All vegetable shortening" which consists of 100% expeller pressed palm fruit oil. There is no trans fat or hydrogenated oils in it and you can buy it for $4.99 which is pretty reasonable.


Steve, Hydrogenated oils are solid at room temperature. To find out if melting them dehydrogenates them, melt them then let them return to room temperature. If solid they are still hydrogenated. If liquid, they are no longer hydrogenated.


anon 39295. the reason for this, as i have come to understand it, is that hydrogenated oils disrupt the metabolic processes of organisms at a cellular level by replacing the functioning parts of the cell with what is believed to be molecularly similar material that does not function as it should in the least. so the metabolic process of, say, the bacteria that would cause the breakdown of these foods, is not taking place, therefore the bacteria are dying off. the same thing happens to our own cells. you'll find various arguments against this but the evidence becomes clearer the more you study. the reason these are legal and various drugs are not is political. it has nothing to do with our health. it has to do with money.


Does melting a hydrogenated oil, dehydrogenate it? Steve


I have the same question as anon39295. I don't think it has been answered yet. I make buttercream with a mix of butter and shortening, and the texture is wonderful for making roses etc. What can I use instead of shortening?


In response to the hydrogenated/partially hydrogenated question, I would think that fully hydrogenated Oils would just be another word for lard, or solid saturated fat. A fully hydrogenated fatty acid cannot have any double bonds, and hence becomes 'saturated' with hydrogen atoms.

So it seems to me, that partially hydrogenated oils are the culprit.

It pisses me off immensley that a label can say that it has no trans-fat, but partially hydrogenated oil is listed in the ingredients. I believe that another poster touched on it.

The FDA has set a standard for an amount of a macro or micronutrient that it considers "miniscule", and if that amount is not met, then it is legal to act as if it is not their at all!

It comes into question though who decides what amounts can slide by.. I question the entire system, considering the FDA(designed to protect buyers from food manufacturers) is essentially run by a handful of people who have served as lobbyists for the meat and dairy industry, and others who worked in high up positions for the coporations themselves.

So you have the leaders of the FDA(indirectly through contributions and former salaries) being paid by the coporations that the FDA is designed to protect us from in the first place!

Thanks for listening to my diatribe.


Nashville, TN


I'm going to give you an example, and I'd just like to have an informed, helpful response. For the last 20 years, I've been making "buttercream icing" with one of the main ingredients being shortening, hi-ratio, hydrogenated shortening. The buttercream stayed perfect for up to a couple of weeks, and it made beautiful, stand-up roses. Always creamy, firm, peaky and fluffy. Now I have to make my buttercream with non hydro and it turns to soup on day two. Help! Susi


While hydrogenated oils are slated by nutritionists, I'd recommend sticking with scientifically proven medicine. You have to be careful when trying to lead a healthy life that you're not taken in by snakeoil salesmen.


What's the difference between palm oil or palm kernel oil, and palm fruit oil?


In response to anon20053... I wanted to answer your question about the difference between partially hydrogenated and fully hydrogenated oils. When a label read hydrogenated __blank__ oil, it means it has undergone an even more extensive process then partially hydrogenated oil, making it even worse for you health wise. If a nutrition facts list says no trans fats, or it is posted on the front of the package but still reads it in the ingredient list, it means that there is less then 0.5 grams per serving (still bad for you!) It is legally allowed to be posted and zero trans fats if it is less then 0.5 per serving... which is awful, but true. All in all, stay away from them completely, there are some natural trace amounts in certain kinds of meats and those are okay, considering they are natural! You also want to avoid high fructose corn syrup, aspartame (fake sugar such as splenda, sweet and low, etc.) and harmful additives such as hydrolized soy protein, enzymes and things that read as "natural flavors." It is extremely important to buy organic produce and meats. I spend lots of time reading up on health uses and I am a strong believer in natural medicine and raw foods... I would be happy to continue discussing anymore questions you may have!


I'm no expert on this issue, but this is an educated guess to the question I think you're asking. "Non-hydrogenated" should indicate a trans-fat FREE product in many cases, because partial hydrogenation produces trans fats. But some trans fats occur naturally. For example, I believe that natural butter could be accurately labeled "non-hydrogenated" and "low in trans fats." There are some trans fats from the milk used to make the butter, just not a lot. Do you have an example of the kind of products to which you're referring?


i just have a simple question... you see, i've done a little research on partially-hydrogenated oils and trans-fats and found out that yes, they are bad for you. But now that i am aware of what i'm eating (looking on the packaging to make sure there's no partially-hydrogenated oils) i'm seeing not PARTIALLY-hydrogenated, but HYDROGENATED oils...

this was on the packaging of my favorite pop-tarts... but there's no trans-fats in the nutrition facts section... hmm...

so my question is what is the difference between partially-hydrogenated and just hydrogenated oils?



what is the difference between Refined palm oil and hydrogenated oil ???


I just want to know why partially hydrogenated oils were not banned with trans fats? How can the food makers get away with their deceptive labels? Doesn't anybody care at all about the consumers who this stuff? Partially hydrogenated oils have been fooling the public for years! why is this allowed?


To add to the comments already here, you also have to watch out for the food industry creatively naming things. Interesterified oil, monoglycinate, mono and diglycinate are all names for hydrogenated oil! Basically what it boils down to, is that you have to make all your own food from scratch if you don't want crap in your body. Especially breads and baked goods as they are the worst offenders, containing not only hydrogenated oil but High Fructose Corn Syrup too!


To further this conversation (I don't know how old it is), Fully Hydrogenated oils do not contain trans fats, but Partially Hydrogenated oils do. Also, it is equally as important to note the Saturated Fat content, and be careful not to substitute Trans Fats with Saturated (which contribute significantly to LDL (bad cholesterol)).


Because of loopholes in FDA rules (which are probably in place to appease food companies), products can claim 0g Trans Fat if the amount of trans fat per serving is less than .5g. So companies increase the amount of serving per package until they get the Trans fat level per serving below the required amount so they can claim 0%. i.e. a snack bag of x claims to have 0g of trans fat per serving and even have a heart healthy advert, but they list the serving portion as 3 servings per snack bag. This means you could really be eating up to 1.5g of trans fat. Read the label. If Hydrogenated or Partially Hydrogenated is included anywhere in the ingredients list it has trans fat regardless of what other boasts the product makes. Watch out for something that has a unusually high number of servings as that is usually an indicator they are trying to hide the trans fat.


I remember reading once how long it took for Hydrogenated Oils to process out of your body and at what percentage it was cleared out as a toxin...Could you remind me of that info!


Trans fats are found in hydrogenated oils.


PLEASE! My question is, What is the difference between trans fat and hydrogenated oils? Because it would seem that hydrogenation produces the trans fat as you say, but then why do some food products claim to be LOW in trans fat AND non-hydrogenated? The food industry really makes me angry and it is terribly tragic these word games that are played on innocent consumers all in the name of profit!!

Thx. Chelsey

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    • Margarine is a common type of hydrogenated oil.
      By: Multiart
      Margarine is a common type of hydrogenated oil.
    • Olive oil is a good example of a healthy fat.
      By: picsfive
      Olive oil is a good example of a healthy fat.
    • Hydrogenated oil is a source of unhealthy trans fat.
      By: Stephen VanHorn
      Hydrogenated oil is a source of unhealthy trans fat.
    • Consumption of hydrogenated oil has been linked with obesity.
      By: olly
      Consumption of hydrogenated oil has been linked with obesity.
    • Hydrogenated oils are often used for frying.
      By: ilolab
      Hydrogenated oils are often used for frying.