Does Soy Increase Prostate Cancer?

Soy is a popular product that millions of people include in their diet. Products that contain soy as an ingredient tend to offer a plant-based source of protein.

This is especially important for people who prefer to consume a diet that primarily consists of plants, such as fruits and vegetables.

While soy is a commonly consumed food, some reports claim the consumption of soy may cause an increased risk of certain cancers. Among men, there are mixed opinions regarding the connection between soy and prostate cancer in particular.

There is some evidence that soy could potentially increase the risk of advanced stages of prostate cancer. At the same time, some evidence points toward a reduced risk of prostate cancer in general.

We consider whether or not men should consume soy products. The focus is to determine if soy would possibly increase a man’s risk of developing this cancer.

What Is Soy?

Soy is quite a unique food or ingredient that is available in various forms today. Soy itself is derived from soybeans, a relatively popular food, especially among vegans and vegetarians.

The use of soy is quite common among people who require a rich source of protein without the need to eat meat products.

The soy that can be extracted from soybeans tends to be rich in various minerals and vitamins. A single cup of soymilk offers about seven grams of protein. Half a cup of soybeans that have been matured and boiled can provide a person up to 15 grams of protein.

These products are also rich in fiber, magnesium, potassium, and several of the B vitamins1.

While beneficial, the consumption of soy is a rather complex topic. Many people believe that soy should be an essential part of their diet. For others, soy is instead seen as “bad” food.

This is due to the reports of soy possibly causing side-effects in the body. These side-effects are often associated with the estrogenic activity that soy may have in a person’s body.

Soy is most commonly taken through oral administration. There are many products on the market that contain soy extracts. Additionally, certain topical medicines also contain soy.

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The Link Between Soy And Prostate Cancer Risk

When looking at the effects of soy, many are concerned about cancer. Several reports claim soy and prostate cancer might be linked. Some reports also claim that a connection between soy and breast cancer exists.
Unfortunately, this is not a straightforward topic.

Even though soy offers plant-based protein, as well as vitamins and minerals, there are still concerns. Clinical trials tend to find mixed results. This makes it hard for people looking to improve men’s health. Men are not sure if they should include soy in their diet, or rather avoid it.

To better understand this connection, it would be useful to consider studies. Several studies have looked at soy and prostate cancer.

Observational studies have also provided evidence. One report3 claims that 267,000 men were analyzed. The report considered 30 previous studies. A total of 267,000 male patients were included in these studies. Specific soy foods were considered in the study. These consisted of the following:

  • Unfermented soy foods (soy milk and tofu, as well as soybeans)

  • Fermented soy foods (natto and miso)

The report provides strong evidence of a positive link between soy and cancer in prostate tissue. It seems there may be a reduced risk in men who consume more soy.

On the other hand, some studies show an adverse link. In one report4, claims are made that the risk may be increased. According to a 2017 International Journal of Cancer study, soya may NOT be one of the best foods that a man should eat if he fears prostate cancer.

The study was performed at Indiana University and was based on data analysis of 27,004 men that were involved in the Prostate, Lung, Colorectal & Ovarian Cancer Screening Trial.

After a follow-up of 11.5 years of the people in the study, the scientists identified 2598 cases of prostate cancer, of which 287 of these were advanced cases.

The researchers also analyzed how much of the men’s diet was high in isoflavones and how that amount correlated with prostate cancer.
Soya is one of the highest sources of isoflavones in the diet. This includes all forms of soy – soybeans, soybean oil, soymilk, soy sauce, and fermented soybean products such as miso, natto, and tempeh.

Isoflavone is similar molecularly to 17-beta-estradiol, an estrogenic compound – and the fear has been that any estrogenic influence on the prostate will make the prostate cells mutate or cause enlargement of the gland.

Extra estrogen in the body is never a good thing.

The answer to the connection between soy and prostate cancer was a bit surprising to the researchers.

The higher the level of isoflavones in the diet, the greater was the risk of the man developing prostate cancer – the advanced type.

There was no connection, though between how much isoflavones were in the diet and the risk of non-advanced prostate cancer.

This study brings up quite a few things that need to be considered:

1) First of all, soya is one of the top GMO foods, which technically aren’t even foods; they are genetically modified organisms. Why are people still eating these non-foods? If the body wasn’t designed to eat GMOs, then can’t we expect nothing but health problems from them? Is it so surprising that the worst type of cancer was associated with those who had the highest consumption of isoflavones, and thus soy?

2) Studies on GMO’ foods’ show that their DNA is absorbed and digested by our bodies and becomes part of us, affecting our DNA over time.

3) Soy has also been found to affect the thyroid negatively. Soy is one of the foods that suppress the hormonal activity of the thyroid gland.

4) Soy is high in anti-nutrient chemicals such as trypsin inhibitors and phytates. These interfere with protein absorption and the absorption of minerals such as zinc and iron needed for health.

5) Infants that are consuming soy formula are getting the equivalent of 4 birth control pills a day. Yes, you are an adult, not an infant, but what was the effect of infant formula on predisposing the cells to cancer in the first place? What could be done to interrupt the connection here? To what extent does the consumption of soy now influence these previous existing connections?

6) Dietary intake is only one influence on the health of prostate cells. One other type of influence is toxins from the waste matter in the body. The prostate is very close anatomically to the rectum.

What is the effect of a considerable accumulation of waste matter in the colon on the prostate cells?

Is there a connection between this and how the cells that are influenced by soya and GMO foods and the waste matter?

There have been natural health practitioners that reversed prostate issues through a series of colonics, proving that excess waste matter in the colon contributes to a lack of health of the prostate.

A 2018 article in the Journal of Mass Spectrometry found high concentrations of two endocrine disruptors — daidzein and genistein — in this type of meat substitute. These isoflavones increase estradiol in men.

Genistein, in particular, has controversial effects on human health. A 2016 review in Food Chemistry described a cancer-destroying property of genistein at low doses. However, the opposite, a cancer-promoting effect, may occur at high doses. The latter finding shows the value of keeping your phytoestrogen intake low.

What Are The Pros Of Soy?

Soy and soybeans have several potential benefits to offer a person.

The primary benefit of soy that should be noted here is the plant-based protein that these foods offer. Protein is essential for all cells in the human body. When there is too little protein in the body, a person is at risk of several complications. This includes a weaker immune system.

There is little saturated fat in soy. Soy products also contain a very low amount of cholesterol. This means people with heart disease have no need to fear this source of protein.

The fiber content in soybeans also aids the digestive function. Fiber is a helpful compound that improves the health of the gastrointestinal tract. Fiber also helps a person feel fuller for longer. This makes weight maintenance easier in the long run.

What Are The Cons Of Soy?

Common side-effects of soy consumption may include:

  • Bloating

  • Nausea

  • Constipation

These side-effects are usually mild.

An allergic reaction to soy is possible. In this case, the following symptoms may develop:

  • Itching

  • Rash

A more severe reaction known as anaphylaxis can occur. This is rare, however. Anaphylaxis can be a life-threatening condition.

Soy may also affect thyroid function. People with hypothyroidism might want to avoid using these supplements. The condition may be worsened with the consumption of soy products.

Certain drugs may also interact with soy consumption. Some of these drugs include:

  • MAOI anti-depressant medication

  • Certain antibiotic drugs

  • Hormone therapy that includes estrogens

  • Tamoxifen (sold under the brand name Nolvadex)

  • Warfarin (sold under the brand name Coumadin)

  • Drugs that contain chemicals that are changed in the patient’s liver

How Can You Overcome The Cons Of Soy?

Due to the presence of certain side-effects, people are often concerned about increasing their intake of soy. There are ways to overcome the potential cons that have been linked to soy. In some cases, however, avoiding soy could be a more appropriate solution.

A person with an allergy to soy hulls are best avoiding these products. Allergies are sometimes permanent. Which means the person is not likely to outgrow their allergy to soy products. Failure to recognize the risk may lead to severe side-effects.

When a person uses drugs that interact with soy, a consultation with a doctor can be useful. There are cases where medications can be adjusted or changed. In this case, the patient might be able to increase their soy intake.

What Negative Effects Can Soy Have On Men’s Health?

One report explains about a man who developed gynecomastia. At first, the doctor did not understand what the cause could be. The reason for the gynecomastia was the high estrogen levels in the patient’s body. Estrogen is a female sex hormone.

There is some estrogen in men but at very low levels. Increased soy intake may cause an increase in estrogen levels. This may then lead to gynecomastia. The term gynecomastia refers to an enlargement in the breasts of men.

Alternatives To Unfermented Soy Products

Due to the estrogenic effects, we do not recommend soy. There are a couple of alternatives that people may consider. These include:

  • Green peas

  • Fresh fava

  • Lima beans

  • Chickpea

  • Quinoa

  • Coarse bulgur

  • Coconut aminos

  • Goat’s milk

  • Hemp milk

How To Lower Estrogen Levels?

As we have discussed, high levels of estrogen in men can cause problems. If you’ve already found yourself subject to estrogen dominance, the most important thing is to reduce the amount of estrogen in your blood.

To do this, you may need to consider taking supplements. This is where Estro Clear comes in.

When men have a higher ratio of estrogen to testosterone in their blood, often their body converts some of the testosterone to dihydrotestosterone (DHT). DHT is highly inflammatory. This inflammation can lead to BPH or, in severe cases, prostate cancer.

To remedy the high levels of estrogen and reverse the effects of estrogen dominance, I would advise trying Estro Clear.

It’s designed to improve libido and strengthen erections, reduce inflammation caused by BPH, protect against prostate cancer, and rebalance hormone levels. Estro Clear contains diindolylmethane, which is naturally extracted from cruciferous vegetables. Research has shown that diindolylmethane reduces the level of estrogen in the blood over time.


  1. Harvard T.H. Chan School of Public Health. Straight Talk About Soy. [online] Available at:
  2. Reger, M., et al. Dietary intake of isoflavones and coumestrol and the risk of prostate cancer in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Internat J Cancer 8 Nov 2017;142,4.
    2 MDPI Nutrients. (2018)
  3. Soy Consumption and the Risk of Prostate Cancer: An Updated Systematic Review and Meta-Analysis. [online] Available at:
  4. UC Berkeley School of Public Health. (2018) Does Eating Soy Foods Reduce Prostate Cancer Risk? [online] Available at:
  5. Journal of Fertility and Sterility. (2010) Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis. [online] Available at:
  6.  Cultures For Health. Why Ferment Soy? [online] Available at:

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