Soy Myths and Facts

Soyfoods have gained greater acceptance and adoption in the U.S. and beyond. Traditionally a staple in Asian cuisines for centuries, soyfoods are a nutritious and beneficial addition to your diet. Soy protein is high-quality, providing essential amino acids the body needs, among other benefits. And heart healthy soybean oil is the most widely used edible oil in the U.S.

Despite the rise in popularity, myths about soy still persist. Many of these are primarily based on animal studies without clear evidence regarding the impact on humans. Keep scrolling as we debunk popular soy myths and learn the truth about soy.

1. Myth_ Soy Affects Reproductive Hormones

Myth: Soy Affects Reproductive Hormones

Soybeans contain a compound called isoflavones, which are classified as phytoestrogens, or plant-based compounds that look like estrogen. This has led to the myth that soy negatively affects reproductive hormones. These myths stem from outdated studies that found a decrease in testosterone or an increase in estrogen in both of their male volunteers. However, if you eat a balanced diet, you likely have nothing to worry about, as the study’s participants were consuming nine times more isoflavones than the average man living in Japan.

Current studies suggest that soy has no effect on reproductive hormone levels in men or women. In addition, none of the studies looking at soy and men’s health found that soy caused men to develop breasts.

Soy Causes Fertility Issues Myth Image

Myth: Soy Causes Fertility Issues

Studies haven’t found a link between infertility and soy consumption. In fact, soy has been linked to healthy birth rates and may make it easier to get pregnant in certain situations. Men can safely consume soy without worrying about their fertility, as there’s no evidence that soy decreases male sperm count.

Myth_ Soy is Bad for Your Thyroid

Myth: Soy is Bad for Your Thyroid

The myth that soy negatively affects your thyroid comes from outdated in-vitro studies and experiments on rats. According to new data, there’s no evidence that soy consumption negatively affects your thyroid or metabolism, even for people with hyperthyroidism.

Soy Causes Breast Cancer Myth

Myth: Soy Causes Breast Cancer

Since soy-consuming countries experience lower rates of breast cancer than their counterparts, soy might play a role in the prevention of breast cancer. However, due to the phytoestrogens in soy, the myth that soy causes breast cancer is still popular.

Unfortunately, there aren’t any studies following women with breast cancer who eat soy. There are studies on soy’s impact on breast tissue development—a common market for breast cancer—that don’t associate soy with any increased risk. In addition, multiple cancer research organizations agree that soy is safe for women with breast cancer.

Soy Causes Poor Mineral Absorption Myth

Myth: Soy Causes Poor Mineral Absorption

Since some soyfoods contain important nutrients such as iron, zinc, and calcium, soy alternatives can be used to replace meat and dairy among plant-based consumers. However, soy is high in phytate, a compound that can impact the body’s ability to absorb zinc and iron.

Most consumers absorb only moderately less zinc from soy than they do from meat or dairy. However, if you eat a plant-based diet, you might want to add additional zinc-rich foods or take a supplement.

When it comes to iron and calcium, studies show that our bodies absorb more iron from soy than we previously thought. In addition, your body absorbs a similar amount of calcium from soy milk as it does from dairy milk.

Soy Allergies Are Common Myth

Myth: Soy Allergies Are Common

Like any food, soy can cause allergic reactions in sensitive individuals. Soy is considered one of the big eight allergens—eight foods that are responsible for 90% of all allergic reactions in the United States. However, studies show that soy allergies are the least common among the big eight. In fact, you’re five to ten times more likely to be allergic to dairy than soy.

Soy Formula Is Bad for Infants Myth

Myth: Soy Formula Is Bad for Infants

Soy infant formula (SIF) has been around for over 60 years, and an estimated 20 million Americans have used soy formula at some time. Even though it’s popular, some parents avoid SIF due to the myth that it’s unsafe.

In 2009, the U.S. National Toxicology Program (NTP) concluded that SIF was safe. SIF is appropriate for healthy infants, even during a growth spurt, and doesn’t delay any normal development.

Soy Causes Early Puberty Myth

Myth: Soy Causes Early Puberty

Many people believe the myth that soy can cause children to start puberty early. However, none of the research on this topic found evidence that soy consumption causes early puberty onset in young girls.

In a study following prepubescent boys, eating moderate to large amounts of soy was associated with developing pubic hair earlier than the group that ate less soy. However, the study didn’t find any link between eating soy and growing facial hair, which was the secondary measure of puberty onset. Also, even among the participants that ate a lot of soy, puberty onset was still later than what’s typical for boys in the U.S.

Processed Soy Products Are Bad for You Myth

Myth: Processed Soy Products Are Bad for You

In the U.S., soy is used in a variety of popular products, including meat substitutes and energy bars, which consist of soy protein. The food industry has been adding soy protein to its products for decades due to its safety and texture.

Frequently Asked Questions About Soy


Now that you know the nutritional benefits of soyfoods, try incorporating them into your diet with one of our soy recipes. Interested in soy production and sustainability? Visit our Soy Farming page for more information.

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