Soy 101: Health Benefits, Food Sources & Common Concerns

Over the past decade, soy has been a hot-button health topic. While the health benefits of soy are largely backed by science, some research suggests that it may cause some health-related issues.

“So, is soy healthy or not?” you ask.

Generally speaking — yes, soy can serve as a healthy addition to a well-rounded diet. Most of the reported health concerns have stemmed from inconclusive studies or been debunked altogether. But as with most nutrition-related topics, the answer isn’t black and white.

To help you decide if soy is right for you, read this foolproof guide covering everything you need to know about soy!

What is Soy?

Soy — short for soybeans or soya beans — is an edible bean belonging to the legume family. It is a complete source of plant protein, meaning that it contains all of the essential amino acids our body needs from dietary sources. Soy is also higher in fiber and lower in saturated fat than animal proteins.

soy-based meat offers soy health benefits

Soy can be found in whole-food sources or processed into soy products, such as soybean oil, soy sauce and soy-based meat analogues (plant-based imitations). However, processed soy products tend to have lower nutritional value and often contain added sodium and preservatives. To reap the full health benefits of soy, stick to whole-food sources of soy, such as soybeans, edamame and tofu.

What are the Health Benefits of Soy?

Soy has been studied over the past several decades. Although current studies are promising, more research is needed to draw stronger conclusions on the health benefits of soy.

May Lower Blood Pressure

Several studies suggest that soy may improve certain markers of cardiovascular health, including blood pressure. A recent study concluded that soy isoflavone and soy protein supplementation significantly decreased systolic and diastolic blood pressure in adults, and provided an even greater reduction in younger participants and those with lower blood pressure. [2][3]

soy health benefits include heart health

May Lower Cholesterol Levels

In addition to blood pressure, soy may also improve cholesterol levels. According to one study, soy protein intake may be linked to a significant reduction in LDL cholesterol and total cholesterol. These results are similar to those found in other meta-analyses. [4][5]

May Increase Bone Mineral Density

In short-term studies, soy isoflavones have shown to help increase bone mineral density, which is often low in adult populations. However, a few long-term studies have been unable to replicate these results. More research is needed to determine if long-term soy isoflavone intake can improve bone health. [1]

May Reduce the Risk of Breast Cancers

Despite claims that soy increases the risk of breast cancer due to its plant estrogen properties, recent research has debunked this myth. Studies show that soy can potentially reduce the risk of developing breast cancer. Additionally, eating soy after a breast cancer diagnosis may decrease potential recurrences of the disease in post-menopausal women. [1][6]

soy health benefits include a reduction in menopause symptoms

May Reduce Symptoms of Menopause

Hot flashes are a common symptom of menopause and may even last several years into the post-menopausal state. Research has shown that consumption of soy isoflavones may reduce the frequency and severity of hot flashes in menopausal women. [1]

Is Soy Healthy for Everyone?

Although the health benefits of soy are well-established, there are specific populations who should limit or avoid soy consumption, including:

Individuals with a Soy Protein Allergy

An allergy to soy is one of the most common allergies as defined by the FDA. This occurs when the body recognizes the protein in soy as a foreign invader and elicits an immune response. If a soy allergy is known, all sources of soy protein should be completely avoided.

People with Decreased Thyroid Function

Soy may interfere with the absorption of certain medications used for the treatment of hypothyroidism. If you’re being treated for hypothyroidism, speak with your doctor prior to regularly consuming soy products. [1]

Important note: If you’re uncertain about consuming soy due to personal medical conditions, speak with your primary care physician for additional guidance and advice.

What are the Best Food Sources for Soy?

Soybeans

Soybeans are part of the legume family and have long been a staple in Asian diets. Whether you prefer to eat them whole or work them into pasta, salads or soups, soybeans offer plenty of culinary versatility. One cup of cooked soybeans contains 30 grams of protein.

edamame offers soy health benefits

Edamame

Edamame beans are immature soybeans that are green in color, unlike their more mature, yellow counterparts. For a savory starter plate, steam and salt edamame and serve it as finger food. One cup of edamame contains 18 grams of protein.

Tofu

Despite its funky appearance, tofu is delicious, diverse and shockingly cheap. Tofu’s texture ranges from soft to extra-firm. One cup of tofu typically contains 44 grams of protein, although firmer tofu tends to contain higher protein content.

Tempeh

Tempeh is made by fermenting cooked soybeans and then forming the mixture into a firm, dense block. It’s typically chunky and offers a nutty flavor profile. Tempeh is a versatile plant-based ingredient commonly used in salads and soups or as an alternative to meat in sandwiches and burgers. One cup of cooked tempeh contains 30 grams of protein.

tempeh is rich in soy

Soy Milk

Soy milk is a popular lactose-free, plant-based alternative to traditional milk. It’s rich in iron, antioxidants and vitamin K. Soy milk can serve as a refreshing standalone drink or a healthy alternative to coffee creamer. One cup of soy milk contains 6 grams of protein.

Does Soy Increase Estrogen Production?

Soy contains isoflavones, which have estrogen-like properties. But while structurally similar, the isoflavones found in soy have fewer and slightly different effects on the body than estrogen. In order to see estrogen-level effects, you would need to ingest large amounts of isoflavones. [1]

Sources:

[1] https://www.mdpi.com/
[2] https://www.sciencedirect.com/
[3] https://pubmed.ncbi.nlm.nih.gov/
[4] https://academic.oup.com/
[5] https://pubmed.ncbi.nlm.nih.gov/
[6] https://pubmed.ncbi.nlm.nih.gov/
[7] https://fdc.nal.usda.gov/

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written by

Kara Kash

Kara Kash

RD, LDN

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