Is Soybean Oil Bad for Your Health? 21 Good Reasons to Avoid

Shopping for a healthy cooking oil and not sure what to buy?

Soy Oil with some seeds on wooden background

While you are perusing the grocery store shelves, you might take an interest in soybean oil, and wonder whether that is something you should purchase.

There is contradicting evidence on whether soybean oil is good or bad for you - but on the whole, I would not recommend it.

There are other healthier oils out there for sale.

But I do not expect you to take my word for it.

You came here to learn whether soybean oil is beneficial or detrimental to your health, so I am going to go over both the advantages and drawbacks.

But before we get into that, let’s talk a little bit more about what soybean oil is.

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What Is Soybean Oil?

Question mark formed with soybeans

Soybean oil also known as soy oil is precisely what you would expect given its name.

It is oil derived from soybeans.

In the bottle, you will see that soybean oil’s color ranges anywhere from a dark yellow to a light green.

You know those bottles of ​"vegetable oil​" you see for sale?

​"Vegetable oil​" is a highly nonspecific name, but it turns out that a lot of vegetable oil is made fundamentally out of soybean oil.

The use of soybean oil dates back quite some time.

It was used at least as early as the 11th century BC in China. Its usage may go back even further than that.

For a long time, production and use remained centered in China, where it was a principle crop.

The earliest reference to soybeans in the US shows up in 1804. In the US, the use of the beans was limited to a forage crop.

Eventually, after the China-Japan War ended in 1895, the country began exporting soybean oil cake to Japan, where it was used as a fertilizer.

By 1908 or so, soybeans were being shipped from China to Europe.

Even though references to soybeans date back to the early 18th century in Europe, it was not until the turn of the 20th century that they were imported regularly there.

Nowadays, soybean oil is common in grocery stores all over the world.

Indeed, in the US alone, around 65% of all oils consumed annually are soybean oils.

Soybean oil is used in a few different ways.

First of all, it is sold as a cooking oil, sometimes marketed as ​"soybean oil​" and other times as ​"vegetable oil.​"

Sometimes rather than being sold on its own as an oil, it is included as an ingredient in other foodstuffs for sale.

You will commonly find it listed in margarine, mayonnaise, salad dressing, and coffee creamers which are dairy free.

Secondly, soybean meal is sometimes made into feed for animals (1).

Thirdly, it is used to make around 80% of all biodiesel in the United States.

Finally, soybean oil can be processed to yield lecithin. This substance acts as a lubricant as well as an emulsifier.

You will find lecithin listed as an ingredient in many food products. It helps to keep other ingredients from separating.

You also will find that lecithin is an ingredient used in the coatings on some pills.

KEY POINTSoybean oil is oil derived from soybeans. It has been in use for centuries around the world, with its use originating in China.

Today, it is sold as a cooking oil, and is also an ingredient in many food products.

It is used to make animal feed and biodiesel as well.

​One Problem With Soybean Oil Is Its Short Shelf Life

Golden Soy Oil on dark wooden background (close-up shot)

Soybean oil does not last very long if it is not processed.

For this reason, it is usually subjected to an industrial process known as ​"hydrogenation.​"

This process takes place at a high pressure. During hydrogenation, hydrogen gas is introduced to the oil (2).

A catalyst is used to facilitate the reaction. While the catalyst may vary, it is most commonly powdered nickel.

Hydrogenating soybean oil confers the following benefits:

  • The oil is more stable and has a longer shelf life.
  • The flavor of the oil may also be improved.
  • The melting point of the oil is increased, which makes it more suitable for high temperature food processing applications.

Unfortunately, the hydrogenating process has a few negative effects as well:

  • The ​alpha-linoleic acid (omega-3) of the oil is reduced, resulting in a reduction in the oil’s nutritional value (92).
  • A number of different fatty acid isomers are spawned through the process. There is limited data on their safety.
  • While some people think the flavor profile of the oil improves, others may differ. Indeed, the unwanted flavors which result from the process have a special name: ​"hardening flavors.​"
  • The catalyst which is used in the process may still remain in trace amounts in the oil.
  • The ratio of polyunsaturated to saturated fatty acids in the oil declines.
  • When an oil is ​"fully hydrogenated​" rather than ​"partially hydrogenated,​" trans fats may be introduced.

So you can see how the hydrogenation process which is necessary to prolong the shelf life of soybean oil is a problem in itself.

This is one of the reasons why you may want to consider purchasing a different oil for use in your cooking.

Is there a form of soybean oil which does not require hydrogenation in order to maintain a stable self life?

Actually, yes - but it is not necessarily something you want to be putting in your body either.

Monsanto has developed a kind of soybean oil which contains just 1-3% linoleic acid.

According to the company, no hydrogenation is required for this type of oil.

Of course, obviously this is not a non-GMO product. That alone is a reason to steer clear.

KEY POINT: Because soybean oil has a short shelf life naturally, it is usually hydrogenated. 

This process has a few advantages, but they are easily outweighed by the drawbacks for health, flavor and safety.

Why Is Soybean Oil So Popular?

heap of soy beans and dollar banknotes

While shopping, you will probably notice that soybean oil or "vegetable​" oil is extremely common compared to other oils.

If soybean oil has to be hydrogenated in order to maintain a stable shelf life, why is it so pervasive?

Well, you have to remember that there is a commercial interest at work.

Put simply, soybean oil is relatively inexpensive to produce.

That is why it is usually cheaper than a lot of the other oils which you see on the grocery store shelves.

This is often enough all on its own to get consumers to buy it.

What about the trans fats? In 2006, the FDA did pass a regulation which states that trans fats must be listed on food labels.

The thing is, if the amount of trans fats for a serving is half a gram or less, it can be stated that it contains "zero​" trans fats (3).

Of course, it is up to the manufacturer of the product to decide what constitutes a ​"serving.​"

So manufacturers of soybean oil will often set a serving size which contains half a gram or less of trans fats.

That way they do not have to declare the trans fat content on the label.

Consumers who see their products for sale are none the wiser. They purchase the oil believing that it is free of trans fats when it really is not.

On that note, it is worth mentioning that some products which are sold as soybean oils actually contain soybean oils in combination with other oils which are even cheaper.

These products can be referred to as ​"refined​" soybean oils.  Those which only contain soybean oil are ​"unrefined.​"

In addition to being inexpensive, American Heart Association (AHA) Central Committee Advisory Statement (93​) in 1961 advised Americans to replace their saturated fat intake with polyunsaturated fats.  

This culminated to the accelerated increase in the consumption of soybean oil in the United States as seen in the graph below:

soybean graph

KEY POINT: Soybean oil is everywhere in grocery marts because it is inexpensive to produce and recommended by American Heart Association AHA.

This obviously benefits the manufacturers. 

Consumers continue to buy it because they are trying to save money, and because they are unaware of the trans fats present in the oil.


​Here ​Are ​21 More Reasons to Avoid Soybean Oil​

​The following are more reasons why soybean oil is bad for you:

1. Soybean oil can contribute to obesity.

Being overweight is obviously something that most of us work hard to avoid, both for reasons of health and appearance.

Did you know that soybean oil can contribute directly to obesity?

In fact, studies show (4) that soybean oil can be more obesogenic than coconut oil or fructose.

So if you are trying to maintain a healthy weight or drop a few pounds, soybean oil is not something you want to introduce to your diet.

KEY POINT: Soybean oil has been shown to contribute to obesity, and may do so even more than fructose or coconut oil.

2. Soybean oil can contribute to diabetes.

test blood sugar

The same study referenced above (4) reported that, ​"a diet high in soybean oil is more detrimental to metabolic health than a diet high in fructose or coconut oil.​"

Glucose intolerance and insulin resistance are both made worse by consuming soybean oil.

This means that soybean oil can be classified as diabetogenic.

And needless to say, if you are already diabetic or pre-diabetic, consuming soybean oil is not going to do anything to help your condition. It will only make it worse.

KEY POINT: Soybean oil can contribute to the development or worsening of diabetes. 

For that reason, it is particularly important to avoid it if you are diabetic or pre-diabetic.

Even if you are not, however, there is no reason to take avoidable risks with your health.

3. Soybean oil is bad for your liver.

Another animal study (5) which was investigating the adverse effects of soybean oil on body weight in mice found that soybean oil induced "significant fatty liver.​"

The other oil in the study which was found to do this was peanut oil.

MCT, olive oil, and tea oil did not produce significant fatty liver.

KEY POINT: Researchers have discovered through animal studies that diets rich in soybean oil can induce fatty liver disease.

5. Soybean oil is a pro-inflammatory food.

Close-up of a spoonful of cooking oil

Chronic inflammation plays a role in a number of age-related diseases.

Eating an anti-inflammatory diet is important if you want to avoid developing or worsening those diseases.

According to the nutritional data ​for 1 tablespoon (14g) of soybean oil (6), the fat profile looks like this:

​Nutrient

​Amount

​Total Fat

​​13.5 g

​Saturated Fat

​​2.1 g

​Monounsaturated Fat  

​​3.1 g

​Polyunsaturated Fat  

​7.8 g

​Total trans fatty acids    

​0.1 g

​Total trans-monoenoic fatty acids

​ 0.0 g

​Total trans-polyenoic fatty acids

​​0.1 g

​Total Omega-3 fatty acids

​917 mg

​Total Omega-6 fatty acids

​6807 mg

​Vitamin E

​1.1mg (6% DV)

​24.8 mcg (31% DV)

​There are a couple of things to take note of here. 

The first is that there is a hefty amount of polyunsaturated fat contained in soybean oil, and it exceeds the amount of monounsaturated fat.

The second is that the omega-6 fatty acids significantly outpace the omega-3 fatty acids present in the oil.

When you get more omega-6 fatty acids in your diet than omega-3 fatty acids, that can increase your risk of inflammation and associated diseases (7, 8).

Just to add to the problem, eating a lot of omega-6 fatty acids can reduce your uptake of available omega-3 fatty acids (9).

This can further throw off your ratio, making inflammation problems even worse.

As to the problems with the polyunsaturated fats, I’ll get into that below.

KEY POINT: Soybean oil is an inflammatory oil, which is bad for your overall health.

6. Soybean oil’s polyunsaturated fat content poses further problems.

omega 6 oil isolated on white

Now let’s talk about the high amount of polyunsaturated fat in soybean oil.

First, a little chemistry.

  • Fats which have single bonds are referred to as saturated fats.
  • Fats which have double bonds are referred to as monounsaturated fats.
  • Fats which have two or more bonds are referred to as polyunsaturated fats.

Polyunsaturated fats are something you want to steer clear of to the best of your ability.

Their bonds are more reactive than those of monounsaturated and saturated fats.

That means that when they are heated up, reactions like oxidization are more likely.

Their low stability makes them poor candidates for cooking safely at high heat.

Monounsaturated and saturated fats are more stable.

That means that you can use them to cook at high heats without the same concerns about oxidization.

If you are not clear on why it is important to avoid oxidization in oil, check out this (14) research.

Oxidized fats can harm your cholesterol and blood pressure while also driving up inflammation in your body.

This is bad for your heart and your overall health.

Soybean oil is an oil which is high in these unwanted polyunsaturated fats.

Other oils such as avocado oil have a better profile in terms of the percentages, with monounsaturated fats comprising a larger part of their composition.

KEY POINT: Oils which are high in polyunsaturated fats can oxidize easily at high temperatures.

If you then consume that oxidized oil, you will be introducing a substance to your body which is bad for your health.

As soybean oil is high in polyunsaturated fats, it should be avoided. There are better alternatives out there.

​7. Soybean oil is bad for your cardiovascular health.

As just discussed (14), soybean oil’s tendency to oxidize easily can be deleterious to your heart health.

You can add to that the fact that the high omega-6 fatty acid content also can be detrimental to your cardiovascular system (15).

​So that is two ways in which soybean oil can harm your cardiovascular well-being.

KEY POINT: Because soybean oil is high in omega-6 fatty acids and polyunsaturated fats, it is a poor choice for heart health.

8. The process which is used to make soybean oil introduces nasty solvents.

I have already talked at length about the industrial process used to manufacture soybean oil, so I will not get into it again in too much depth.

I will iterate however that this process involves subjecting the oil to chemical solvents, deodorizers, bleaches, and intense heat.

Here is a flowchart of the manufacturing process:

soybeans process flow

An example of a chemical solvent which may be used in the process is hexane.

Hexane is a neurotoxin (16).

There is some debate as to whether any of the unwanted chemicals remain in the oil after the processing is complete.

Even the University of California is less than reassuring on this matter, nebulously stating (17), ​"Should [you] worry about hexane in soy burgers and other processed soy foods? Probably not, though it’s hard to know for sure.​"

The university further goes on to state that, ​"Testing by Swiss scientists found that the majority of vegetable oils sampled had no detectable levels​ - and those that did fell below the tolerance limit set by the European Union.​"

Good news, right? Well, sure​ - but there is conflicting data.

The university also adds, ​"On the other hand, independent testing commissioned by the nonprofit Cornucopia Institute created a stir a couple of years ago when it found hexane residues in soy oil, as well as in soy grits and soy meal."

So right now the evidence is inconclusive.

soy beans and oil

I don’t know about you, but I prefer to err on the side of caution and avoid any possible toxins in my food when I can.

The fact that the FDA does not currently require that oils be tested for hexane levels before they go to market also does nothing for my confidence.

If you are wondering what the bleaches and deodorizers previously mentioned are for, that is for masking the unusual color and smell of the processed oil.

If these were not used, the oil would neither look nor smell appetizing, and it would be harder for it to sell.

So next time you are standing in front of a grocery shelf and staring at a cheap bottle of soybean oil and thinking about buying it, try to imagine what it really looked and smelled like before it was further ​"refined.​"

Would you be likely to buy that bottle of oil, even if it was priced very cheaply? Probably not.

Remember, the oil you are looking at is the same oil. It just has been disguised through further processing.

KEY POINT: Soybean oil’s processing involves the use of a lot of chemicals which you would not want to eat.

There is some uncertainty based on test results as to whether some of those chemicals (like hexane) remain in the oil after the processing is completed.

9. You are what you eat.

cooking vegetable oils in 3 bottles

Let’s return to the matter of polyunsaturated fats and omega-6 fatty acids.

Later in this article, I am going to give you some recommendations for healthier fats you can use, one of which is lard.

The thing to realize about lard though is that how ​"healthy​" it is depends on what the animal it came from was being fed throughout its life.

Animals that were fed on grains produce lard higher in polyunsaturated fats.

Just as the diets of animals can impact their fat profile, your diet also can influence your fat profile.

The instability of polyunsaturated fat is a problem.

Because the bonds in polyunsaturated fat are more reactive, the likelihood of cellular damage increases.

Even DNA can suffer from the effects (38, 39).

Take a look at this animal study (18). Test subjects which received higher amounts of omega-6 fatty acids were more likely to develop cancer.

In another study (19), it was found that omega-6 fatty acids can increase the likelihood of melanoma by making skin cells more predisposed to UV ray damage.

The quality of the food we put into our bodies has an impact on the structural integrity of our cells.

As seen on the following graph, the linoleic acid (omega-6) content of body fat have increased above 3-folds over the past 50 years (94​, 95, 96, 97, 98, 99):

linoleic body fat vs time graph

​If you eat foods which are overly high in polyunsaturated or omega-6 fatty acids on a regular basis, that may adversely impact your health at the cellular level as a result.

KEY POINT: The omega-6 and polyunsaturated fats in soybean oil can be bad for your health at the cellular level, which may make your body more susceptible to cancer or other health issues.

10. Soy has estrogenic effects.

If there is one thing in your body you do not want to unwittingly mess around with, it is your hormones.

Researchers still have a poor understanding of hormones such as estrogen and how imbalances in these hormones can impact the human body.

We do know however that soy contains phytoestrogens and may thus behave as an endocrine disruptor (20).

The study above states, ​"Lifetime exposure to estrogenic substances, especially during critical periods of development, has been associated with formation of malignancies and several anomalies of the reproductive systems … Prospective epidemiological studies for the evaluation of the effect of phytoestrogens alone, and in combination with other estrogenic chemicals, are lacking, yet possible adverse effects should not be taken lightly.​"

soybeans on sack

Furthermore, estrogen and other hormones modify how we experience pain.

See this study (21) which explains, ​"After the menopause, when levels of estrogen and progesterone are very low, the sex differences in pain become much less marked. However, the use of hormone replacement therapy (HRT) in postmenopausal women has been associated with the development of pain conditions including back and TMJ pain.​"

In short, exposure to excess estrogen can not only destabilize your health, but can make your experiences of those maladies more painful.

Whether you are male or female, that is something you want to avoid, so you should regard unfermented soy products such as soybean oil with great caution.

Right now, we still do not fully understand the impact that soy might have on our hormone production and our short- and long-term health, but some risks may include reduced male fertility, increased risk of breast cancer, and the problems with thyroid functioning (23).

Hormonal imbalances are very common in today’s world, however, and it is reasonable to guess that exposure to phytoestrogens and xenoestrogens is likely a factor.

For many people, this imbalance may start at a young age.

There are infant formulas now containing soy.

Infants that eat these formulas may have levels of circulating phytoestrogens in their bodies which are up to 22,000 times as high as the natural levels of estrogen they should have at that age (22).

Needless to say, there is plenty of cause for concern (24, 25, 26).

KEY POINT: Soy products have an estrogenic effect in the body. This means they can act as endocrine disruptors.

If you do not want to invite hormonal imbalances, it is best to avoid endocrine disruptors.

11. Soybean oil may be carcinogenic.

Chef cooking food in frying pan, close-up

As mentioned previously, if you use soybean oil to fry foods at high heat, the oil’s chemical composition will result in oxidization.

This leads to a number of problems we have already discussed, but there are some further health concerns as well.

When soybean oil is subjected to high heat, volatile compounds such as aldehydes and trans fats form (27, 28).

The omega-6 fatty acids in the oil may break down as well. The resulting compounds are toxic and may have carcinogenic properties (29).

In an animal study (30), rats were fed on diets which included either ghee (clarified butter) or soybean oil.

The rats which ate the soybean oil rather than the ghee had higher rates of cancer as well as larger tumors and more of them.

Additionally, animal studies have also found (31) that oxidized soybean oils can increase oxidative stress in the body.

They can raise blood pressure as well.

KEY POINT: When soybean oil is oxidized through high heat, it can give rise to carcinogenic compounds.

​12. There is a tendency for soybeans to be genetically modified - and contaminated.

If you are trying to go non-GMO with your diet, eating soybean oil will make that hard to achieve.

The vast majority of soybeans are now genetically modified. Just what is the ​"vast majority?​" Around 90% (32).

The reason that these soybeans are genetically modified is so that they can be treated with a pesticide called glyphosate without dying from the exposure.

glyphosate spraying

Glyphosate isn’t just deadly to plants; its destructive effects on human health have been studied (33, 34, 35, 36) as well.

It is possible that it can contribute to neurological disease as well as cancer.

Research has been done (37) to compare the quality of non-genetically modified soybeans not treated with glyphosate with GMO beans which have been sprayed with the pesticide.

It has been found that the non-GMO beans are more nutritious than their GMO counterparts.

Furthermore, trace amounts of glyphosate have been detected on the GMO beans, so these products may be contaminated.

KEY POINT: When you purchase soybean oil, chances are really good that it was made out of genetically modified soybeans which have been treated with harmful pesticides like glyphosate.

These beans are less nutritious than non-GMO beans, and may even be polluted with residual glyphosate.

13. If you eat soybean oil, you will increase your exposure to trans fats.

Previously I talked about how there may be more trans fats in the soybean oil you see on the grocery store shelves than is listed on the labels.

This study (40) examined the fatty acid content of soybean and canola oils.

The researchers found that trans fats accounted for anywhere from 0.56-4.2% of their fatty acid content.

Trans fats can increase your risk for cardiovascular disease, diabetes, obesity, and cancer (41, 42, 43), so it is worth it to stay away from them, even if that means buying other more expensive oils to cook with.

KEY POINT: The trans fats in soybean oils are harmful to your health.

Labeling law loopholes allow manufacturers to be less than transparent about trans fats, so many consumers are not even aware of what they are introducing into their bodies when they purchase soybean oil products.

14. Soybean oil may increase your chances of developing cardiovascular disease.

As just mentioned, the trans fats in soybean oil are bad for cardiovascular health.

A few studies have looked at whether vegetable oils like soybean oil can increase the risk of cardiovascular disease.

Some have found no significant relationship (44, 45, 46, 47), while others (48, 49, 50) have found the increased risk to be significant.

Plus, there is the high omega-6 fatty acid content of soybean oil to consider.

This following graph is from a study where the omega-6 level in the blood was compared to the likelihood of death from cardiovascular disease (51​):

CHD mortality vs omega-6 graph

As you can see, the United States sits at the top right, with the highest Omega-6 AND the greatest mortality rate from cardiovascular disease.

This study shows only correlation, but it makes sense since inflammation is a contributor to these diseases.

Reducing one’s intake of omega-6 fatty acids and increasing one’s intake of omega-3 fatty acids is a key step (51) to preventing cardiovascular disease.

That means abandoning the use of soybean oil and others with a similar omega-6/omega-3 fatty acid profile in favor of those which are higher in omega-3s and lower in omega-6s.

KEY POINT: The trans fats and omega-6 fatty acids in soybean oil can potentially increase your chances of cardiovascular disease.

​15. Soybean oil could potentially increase the chances of developing eczema or asthma.

boy with asthma using inhaler

This study (52) was focused on the presence of omega-6 fatty acids in breast milk and the impact on infant health.

The researchers discovered that children who were exposed to more omega-6 fatty acids this way were more likely to develop asthma and eczema.

So if you are pregnant or nursing, you should be aware that dietary choices like soybean oil can have a negative impact not just on your own health, but on that of your children.

While more research is needed in this area, it is also worth wondering whether the consumption of omega-6 fatty acids can also increase the chances of developing respiratory or skin issues as an adult.

KEY POINT: The omega-6 fatty acids found in soybean oil are associated with higher risk of children developing asthma and eczema.

​16. It is possible that soybean oil could increase the risk for mental disorders.

depressed woman sitting on chair

There are a couple of studies which indicate that soybean oil consumption could put one at risk not only for physical problems, but for psychological ones too.

For one thing, diets which are low in omega-3 fatty acids and high in omega-6 fatty acids can raise the risk for depression (53).

Even more disturbing, the linoleic acid found in vegetable oils such as soybean oil are associated with higher homicide rates (54).

The article linked above reports, ​"Low linoleate diets may prevent behavioral maladies that correctional institutions, social service programs, and mental health providers intend to treat.​"

If that is indeed the case, that is quite a profound reason for societies to move away from soybean oil and similar products.

KEY POINT: The omega-6 and linoleic acid content of soybean oil could predispose those who consume them in high amounts to psychological disorders and violent behaviors.

17. Soybean oil could potentially increase your risk for breast cancer.

Pink badge on woman chest to support breat cancer cause

Earlier I talked about how soybean oil is an endocrine disruptor, and how this can lead to numerous health issues, whether you are a man or woman.

Now I want to focus on one of those concerns​ - the increased risk for breast cancer.

There are multiple animal studies which demonstrate that exposure to isoflavones in soy can increase breast cancer risk (55, 56, 57).

Human studies on breast cancer and soy also exist.

For example (58), there was a study in 1998 where 48 women were divided into a control group and an experimental group.

The control group made no changes to their diet. The experimental group took 60 grams of soy protein every day for two weeks.

At the end of the two-week period, the experimental group displayed greater proliferation of epithelial cells.

These are the types of cells in the breasts which have the highest chance of developing cancer.

Considering that this happened in just two short weeks, it is hard to imagine what might happen over a period of longer exposure (more research is needed).

Another small study (59) did find that soy protein supplementation resulted in similar epithelial increases in a third of participations.

Despite these findings, there are some conflicting studies out there which seem to indicate that soy actually has a protective effect against breast cancer (60, 61).

As these are observational studies, however, the information they provide is limited.

In any case, hormones are a very complex topic.

There are many challenges in understanding them, not the least being the fact that individual hormone profiles vary greatly.

Regardless, the data from these studies certainly is reason to be cautious about soy consumption, especially if you already have high estrogen levels.

KEY POINT: While study results are mixed, there is research which indicates that soy consumption may increase breast cancer risk.

18. Eating soy could throw off your menstrual cycle.

Young woman using hot water bottle on abdomen while lying on bed

Another possible effect of endocrine disruption from soy in women is potentially unwanted changes to the menstrual cycle.

Studies (62, 63) have found that consuming soy can lead to delays during the follicular phase of the cycle.

The broader health implications will likely vary from woman to woman depending on the pre-existing imbalances.

More research is needed, but this is yet another indication that soy modifies how hormones behave in the body.

KEY POINT: Consuming soy-based products like soybean oil could lead to changes in your menstrual cycle.

​19. Soy may have adverse effects on male fertility.

man unhappy

Let’s dive deeper into exploring another of the hormonal problems with soy, this time affecting men.

Men do have estrogen in their bodies, but only at low levels.

So just as exposure to phytoestrogens may adversely impact female health, it can also wreak havoc on male endocrine systems.

There is research backing this up.

In these animal studies (64, 65), rats which were exposed in the womb to isoflavones from soy had problems later with their sexual development.

The results from human studies also indicate that soy can be problematic for male sexual health.

This study (66) found a correlation between high soy intake and low sperm count.

It should be noted that correlation does not equal causality, but the data is enough to give one pause.

Does soy intake impact the quality of semen? Not according to this (67) study.

Research is mixed (68, 69) regarding whether or not soy impacts testosterone levels.

KEY POINT: While study results are inconsistent, there is some research which seems to show that high soy intake could adversely impact male fertility.

20. Soy could potentially lead to hypothyroidism.

woman yawning

Among the isoflavones in soy-based products like soybean oil are goitrogens.   

Goitrogens can interfere with thyroid peroxidase. This enzyme is necessary for thyroid hormone production (70, 71).

This can cause problems with thyroid function which can result in the symptoms of hypothyroidism.

This is exhibited through a 1991 study in Japan (72) on 37 subjects with healthy thyroid function.

Subjects in the study who took 30 grams of soybeans daily over a 3-month period developed symptoms such as constipation, sleepiness, malaise, and even goiter.

The researchers followed up after the subjects stopped taking the soybeans. one month later, the symptoms had ceased.

The researchers concluded, ​"These findings suggested that excessive soybean ingestion for a certain duration might suppress thyroid function and cause goiters in healthy people, especially elderly subjects.​"

While this study had dramatic results, there are others which have shown only slight impairment of the thyroid through soy intake​ - or none at all (73, 74, 75).

Even with the mixed data, it makes sense to be cautious.

If thyroid function is disrupted, it can have cascading results for the endocrine system.

KEY POINT: Soy-based products contain goitrogens which can interfere with healthy thyroid function and even lead to symptoms such as goiter.

21. Soy-based baby formula has a number of risks.

I mentioned earlier how it was found that omega-6 fatty acids in breast milk led to increased incidences of asthma and eczema among developing children.

soy milk

There are a number of studies which have been conducted specifically on soy infant formula which point toward other problems with soy consumption.

Girls who consumed soy-based formula as infants were compared to those who had consumed dairy-based formula or breast milk in this (76) research.

By age 2, the girls who were fed the soy formula had developed more breast tissue than those who did not.

It has also been found that feeding girls soy-based formula when they are infants can cause them to reach puberty earlier (77).

This does not come without additional problems. It can mean longer menstrual cycles as well as more painful menstruation (78).

Incidentally, there are some other issues with soy-based formula as well which go beyond phytoestrogens.

The high manganese content of soy formula can impact neurological development, and may increase the risk for ADHD (7980).

Meanwhile, soy formula’s high aluminum content poses additional dangers (81, 82).

KEY POINT: There are studies which show that soy-based infant formula poses a number of health hazards.

While soybean oil obviously is not the same thing as infant formula, this does further highlight the health issues which may be associated with soy intake, particularly when it comes to throwing off hormonal balance.

22. Soy can cause problems involving blood clots.

Soy contains a substance known as "hemagglutinin.​" 

Hemagglutinin promotes blood clots.

This can lead to issues with tissue health since the blood has a harder time ferrying nutrients and oxygen to your cells.

KEY POINT: The hemagglutinin in soy-based products causes problems with proper blood flow.

​23. Soy-based products can disrupt nutrient absorption.

soybeans in hand

There are some other problematic substances in soy as well, namely anti-nutrients and phytic acid.

Anti-nutrients are naturally occurring toxins.

Some examples include protease inhibitors, soyatoxin, oxalates, and saponins.

With a balanced nutritional diet, you will consume some anti-nutrients, but they should only be present in small quantities.

This means that they do not cause major issues in your body.

In large amounts, however, they can make it hard for your body to digest protein properly.

This is because they interfere with the necessary enzymes.

As to the phytic acid, this can stand in the way of your body absorbing quite a few different minerals.

Some of these include zinc, iron, calcium, and magnesium.

You might wonder if it is possible to cook out the phytic acid.

To some degree, yes​ - but the phytic acid in soy tends to hold up quite well even over a long period of cooking.

The only thing which seems to result in a significant drop in phytic acid content in soy is fermentation.

This is one of the reasons why fermented soy products are considered healthier than unfermented soy products.

Soybean oil is not a fermented soy product. So it is high in phytic acid.

KEY POINT: The phytic acid and anti-nutrients present in soybean oil may make it harder for your body to absorb and digest protein and key minerals effectively.


​Does Soybean Oil Have Any Nutritional Benefits?

Soybean oil in a bottle with green pods and leaves.

With soybean oil having so many disadvantages for health, you may be wondering whether it has any nutritional value at all.

There are some studies which show potential benefits to consuming soy-based products.

In the interest of fairness, let’s take a quick look at them now.

  • Soy may reduce cholesterol and prevent heart disease, but the research is mixed (83, 84, 85, ​86, 87, 88).
  • A couple of observational studies indicate that there is a chance that men who consume more soy have a lower risk of developing prostate cancer (89, 90).

Remember, if you are going to eat soy products, it is best to stick with fermented soy since it contains less phytic acid (91).

But you should know that even fermented soy products contain isoflavones.

That means that they still act as endocrine disruptors, so they are not necessarily a ​"safe​" choice.

KEY POINT: There are some studies which show that soy may have some benefits.

Nonetheless, that does not mean that soybean oil is good for you. 

The drawbacks greatly outweigh the possible benefits.

If you plan to eat soy products at all, you should stick with those which are fermented - and you should moderate your intake of those as well, since they can still disrupt your hormones.

What Are Some Healthier Alternatives to Soybean Oil?

You now are familiar with both the health benefits and drawbacks of soybean oil.

As you can see, the drawbacks outweigh the positive effects.

For that reason, you probably will want to shop for a different oil to use in your cooking.

Being as many of the other cooking oils are more expensive than soybean oil, you will want to choose something carefully which will provide you with the flavors you want, the nutritional value you need, and a price you can afford.

So which oils are worth considering?

Here are some of the healthiest oils you can cook with (if you want to see the studies I mention, please check out 6 Healthiest Oils to Cook With):

Coconut oil

coconut oil on wooden spoon

This oil has quite a few benefits.

For one thing, it is very stable, and will not break down even if you are cooking with it over a long time period at a high temperature (10).

For another thing, there are quite a few studies which indicate that it has numerous health benefits.

Some of these include faster calorie burning and weight loss, fighting plaque and gingivitis, improving cholesterol, getting rid of visceral vat, and improving satiety.

You can also use coconut oil to reduce inflammation and treat epilepsy.

Butter

Butter

So long as you will not be using very high heat, butter is a good option (if you use really high heat, it can burn).

It is quite nutritious, with vitamins E, A and K2 along with the butyrate and Conjugated Linoleic Acid (CLA) fatty acids.

There are studies which show that these healthy nutrients can fight inflammation, reduce body fat, and even suppress cancer growth (probably not what you expected, considering how long butter has been demonized).

Olive oil

olive oil in jug

Olive oil is largely comprised of monounsaturated fats.

You do need to shop around to makes sure that you are getting olive oil which is high in quality, but if you do, you will discover it can have some great benefits.

In terms of nutrition, it is very high in vitamins K and E.

It also contains a special antioxidant and anti-inflammatory agent called oleocanthal which can boost heart health (11) and act as a painkiller (12).

Olive oil has other health benefits as well, and is a core part of the popular Mediterranean diet.

You can cook with olive oil even at high temperatures safely, which makes it great for a variety of recipes.

Avocado oil

Avocado oil on table close-up

Like olive oil, avocado oil is high in monounsaturated fats as a percentage of its overall composition.

With its high smoke point, it too can be safely used for cooking even at high temperatures.

Both olive oil and avocado oil contain a monounsaturated omega-9 fatty acid which is referred to as ​"oleic acid."

This fatty acid (13) can help lower high blood pressure.

Avocado oil also can improve overall cardiovascular markers and even has benefits for arthritis, eye health and more.

Macadamia nut oil

Bottle of macadamia nut oil isolated on white background

This oil is a bit pricey compared to a lot of others (exactly as you would probably expect, given that the same is true for macadamia nuts), but it is another healthy choice.

Its flavor profile can be described as "buttery,​" and its monounsaturated fat content is high, like that of olive oil.

It is rich in antioxidants and does not contain a lot of unhealthy omega-6 fatty acids.

Lard

Lard

Lard, bacon drippings, tallow and so on can be healthy cooking oils - but only if the animals they came from were grass-fed instead of grain-fed, as previously mentioned.

The diets of the animals affects the percentage of their fat which is polyunsaturated versus monounsaturated.

And here are some other oils which you also will want to avoid in your cooking:

  • Rice bran oil
  • Corn oil
  • Canola oil
  • Sesame oil
  • Grape seed oil
  • Safflower oil
  • Sunflower oil
  • Cottonseed oil

Again, there is a lot of science to check out here.

If you want to read in-depth about the best oils to cook with, check out my article 6 Healthiest Oils to Cook With

There you can view the research on the recommended oils.

KEY POINT: Since you are probably going to want to avoid soybean oil, you will need to choose another type of healthier oil for your cooking.

To that end, you should avoid rice bran oil, canola coil, corn oil, sesame oil, safflower oil, grape seed oil, cottonseed oil and sunflower oil.

You should instead consider purchasing any of the following healthy oils: avocado oil, macadamia oil, olive oil, lard, butter, or coconut oil.

Conclusion: Soybean Oil Is Best Avoided

While there are a few research studies which show that soy may have some health benefits, there is a larger body of evidence which suggests that soybean oil is bad for your health on multiple levels.

On the whole, there are a number of other cooking oils which are much better for you.

For that reason, you should consider paying a little extra at the grocery store for avocado oil, coconut oil, or another healthy oil.

Look for other areas of your food budget where maybe you can save and make up the difference.

It may involve some logistical challenges in the short run, but in the long run, your body will thank you.

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  • Updated September 29, 2018

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