Is Soy Safe?

by Emily Harland, RDN, CSO, LDN

Last Updated: August 10, 2021

The safety and health benefits of soy have been debated. For some, it’s declared as an essential meat alternative, and for others, it is avoided due to fear of negative health effects. So, what’s the truth? Let’s dive into the research surrounding soy and answer this question once and for all.

Basics of Soy and Soy Nutrition
Soy comes from soybeans, a vegetable in the legume family. The beans can be eaten whole or processed into various different products, including soymilk, tofu, miso, tempeh, soybean oil, or soy nuts. Soybeans are high in protein, which makes them an excellent meat alternative for those following plant-based diets. Soybeans are also higher in fat than other beans and contain essential healthy fat types: omega-6 and omega-3. There are also complex carbohydrates found in soybeans that provide fiber and promote healthy digestion and gut health. Soy is also a source of iron, folate, vitamin c, potassium, magnesium, and calcium.

Soy and Breast Cancer
Confusion about soy arises from the term "phytoestrogens." Some soy nutrients—the isoflavones—have chemical structures that look a bit like the estrogen found in a woman's body. This is where the term phytoestrogen originated. However, phytoestrogens are not the same thing as female estrogens. Soy foods do not contain estrogen or cause breast cancer. On the contrary, soy is a rich source of isoflavone phytochemicals which may protect against hormone-dependent cancers. In moderate amounts, which means one to two servings/day of whole soy foods (like tofu, edamame, and soy milk) may be included as a part of a balanced diet. Not only is soy safe in moderate amounts, but research shows that soy contains isoflavones, a phytonutrient with anti-cancer properties.

Soy and Thyroid Function
Despite the potential nutritional attributes of soy foods, there has been much consumer concern about their interference with thyroid health, especially among individuals whose thyroid function is already compromised. Currently, there is not enough research to show that soy food intake is detrimental to thyroid health. If you are being treated for thyroid disease, speak with one of our Kroger Health Dietitians to find the best way to incorporate soy foods into your diet, as there may be special considerations depending on the treatment method. In general, however, consuming whole soy foods several times per week as part of an overall, balanced diet is recommended.

What Soy Foods Should I Consume?
Whole soy foods, like tofu, edamame, and soy milk, are recommended over isolated soy protein or isoflavone supplements (found in many protein bars/powders) because whole soy foods provide a wider variety of nutrients and other bioactive compounds. Here are some great ways to incorporate whole soy foods into your diet:
  • Breakfast
    Whole grain cereal topped with soy milk and berries
  • Lunch
    Bean Salad made with edamame, black beans, corn, red peppers, and lime juice- serve as a side or on top of a salad!
  • Dinner
    Tofu Stir Fry with brown rice and vegetables
  • Snack
    Whole edamame pods with sea salt

The Bottom Line
Whole soy foods are an excellent source of protein, fiber, complex carbohydrates, vitamins, and minerals and may be consumed daily as an excellent plant-based protein source. Aim to choose whole soy products like edamame, tofu, soy milk, and tempeh over more processed forms of soy (i.e. protein isolate) for optimum health benefits.

Disclaimer: This information is educational only and not providing healthcare recommendations. Please see a healthcare provider.

Emily Harland, RDN, CSO, LDN

Emily Harland, RDN, CSO, LDN

Emily is a passionate clinical dietitian who strives to make nutrition changes sustainable while improving peoples’ relationship with food. She makes every effort to get to know each one of her clients on a personal level to ensure whole-person care. Emily is specialized in nutrition for oncology and cancer prevention/treatment. She has expertise from diabetes and heart health to hormonal health and fertility issues. Emily is an avid indoor cyclist and loves spending time in the kitchen cooking up nutritious and energizing meals.