Soy, a product derived from soybeans, is a staple in many diets around the world and is central to many vegetarian and vegan diets due to its high protein content. However, it has been the subject of various myths and misconceptions, some of which have been debunked by scientific research. Here are some of the most common myths and the truths behind them:

Myth 1: Soy Causes Breast Cancer

Misconception: Soy contains isoflavones, which are plant estrogens (phytoestrogens). Some people have claimed that these could increase the risk of hormone-related cancers like breast cancer.

Reality: The majority of human studies have not found a link between soy consumption and increased breast cancer risk. In fact, some research suggests that it may have a protective effect, particularly when consumed during adolescence. The American Cancer Society acknowledges that soy foods are healthy and nutritious for both cancer survivors and the general population. 1

Myth 2: Soy Affects Male Hormone Levels

Misconception: Another common myth is that soy consumption can negatively impact male hormone levels, particularly testosterone, due to its phytoestrogen content.

Reality: Clinical studies generally show that soy does not exert feminizing effects on men. Soy consumption does not significantly influence male hormone levels to any clinically relevant degree. Soy foods do not have adverse effects on men and may contribute to prostate health.

Myth 3: Soy is Unnatural and Highly Processed

Misconception: Some believe that all soy products are unnatural and the result of high processing, including the use of genetically modified organisms (GMOs).

Reality: While many soy products are highly processed (e.g., soy protein isolates and textured vegetable protein), there are also minimally processed forms of soy, such as edamame, tofu, tempeh, and soy milk. Organic and non-GMO soy options are widely available for those concerned about genetically modified ingredients.

Myth 4: Soy is Bad for Thyroid Health

Misconception: It is often claimed that soy can interfere with thyroid function and can contribute to hypothyroidism or exacerbate existing thyroid problems.

Reality: Soy might have goitrogenic properties, which can interfere with thyroid hormone production, but this effect is usually minimal and not a concern for people with normal thyroid function. Those with thyroid issues should manage their soy intake in consultation with a healthcare provider, but it generally does not need to be completely avoided.

Myth 5: Soy Has No Health Benefits

Misconception: Some people argue that soy has no real health benefits and shouldn’t be part of a healthy diet.

Reality: Soy is a good source of protein, essential amino acids, fiber, and various vitamins and minerals. It has been associated with various health benefits, including improved heart health, potential protective effects against certain cancers, and a lower risk of osteoporosis.

Myth 6: Soy is Always Good for the Environment

Misconception: A common belief is that soy products are inherently more environmentally friendly than meat-based products.

Reality: While the production of soy is generally more resource-efficient and emits fewer greenhouse gases than meat production, there are environmental concerns associated with soy, such as deforestation and the use of pesticides and herbicides in soy agriculture, especially in regions like the Amazon. Choosing sustainably grown soy can mitigate some of these impacts.

Myth 7: Soy is a major allergen.

Fact: Soy allergy is relatively rare, affecting about 0.5% of children and even fewer adults. People with soy allergy should avoid all soy products, but most people can safely consume soy without any problems.

Overall, the scientific evidence suggests that soy is a safe and healthy food for most people. It is a good source of protein, fiber, and other important nutrients. Soy foods can be enjoyed as part of a balanced diet, along with other fruits, vegetables, and whole grains.


It’s important to note that while soy can be a beneficial part of the diet for most people, individuals may have specific health concerns or conditions that require dietary adjustments. As with any dietary choice, moderation and variety are key, and it’s advisable to consult with a healthcare provider or a registered dietitian for personalized nutrition advice. Additionally, nutrition science is always advancing, so it’s good to stay informed with the latest research.


1 – Wei Y, Lv J, Guo Y, Bian Z, Gao M, Du H, Yang L, Chen Y, Zhang X, Wang T, Chen J, Chen Z, Yu C, Huo D, Li L; China Kadoorie Biobank Collaborative Group. Soy intake and breast cancer risk: a prospective study of 300,000 Chinese women and a dose-response meta-analysis. Eur J Epidemiol. 2020 Jun;35(6):567-578. doi: 10.1007/s10654-019-00585-4. Epub 2019 Nov 21. PMID: 31754945; PMCID: PMC7320952.

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