Soy (or soya) refers to various foods derived from the soybean plant, including:
- Soybeans: the whole, mature beans, often sold dried or fresh
- Tofu: a soft, cheese-like food made by curdling soy milk
- Tempeh: a fermented soy product with a nutty flavour
- Soy milk: a non-dairy milk alternative made from grinding and boiling soybeans
- Edamame: immature soybeans often served as a snack or side dish
- Soy sauce: a condiment made from fermented soybeans, salt and wheat
- Textured vegetable protein (TVP): a high-protein product made from defatted soy flour
Soy is widely used in many Asian cuisines, and has also become popular as a plant-based alternative to meat and dairy. It's a good source of protein and contains various vitamins, minerals and phytochemicals beneficial to health. Some people, however, have soy allergies or are sensitive to certain components of soy, such as its isoflavones, so it's worth monitoring your own reactions to it.
What Is a Soy Allergy?
A soy allergy is an allergic reaction to proteins found in soybeans and soy-based foods. Symptoms may include itching, swelling, hives, difficulty breathing, vomiting and diarrhoea. If you suspect you or a loved one may have a soy allergy, it's important to seek medical advice. If an allergy is confirmed, avoiding foods containing soy and soy-based ingredients becomes essential – common sources include edamame, tofu, miso, tempeh, soy sauce, soy milk and various processed foods. Reading food labels carefully helps identify hidden sources of soy too.
Soy is a legume, which means anyone with a confirmed soy allergy may also want to be cautious around other legumes, including chickpeas and lupin, due to shared proteins that can occasionally trigger cross-reactivity.
What Foods Contain Soy?
Soy appears in many foods, either as a primary ingredient or as an additive. Common sources include:
- Tofu
- Tempeh
- Soy milk
- Edamame
- Soy sauce
- Textured vegetable protein (TVP)
- Vegetarian meat alternatives (veggie burgers, sausages, meatballs)
- Dairy alternative products (soy-based yoghurt, cheese, creamers)
- Baked goods (bread, crackers, pastries)
- Snacks (granola bars, protein bars, energy bars)
- Processed foods (canned soups, sauces, broths, salad dressings)
Always check ingredient labels when shopping, as soy can appear under different names, such as soy protein isolate or hydrolysed soy protein.
What Are the Symptoms of Soy Intolerance?
Soy intolerance is different from a food allergy – it's a sensitivity to certain foods containing soy, rather than an immune reaction. Symptoms may include digestive issues such as bloating, gas, abdominal pain, constipation or diarrhoea, alongside fatigue, headaches, skin rashes or joint pain in some people.
If you suspect a soy intolerance, our food intolerance test can help identify it. Managing soy intolerance means eliminating soy and soy-based foods from your diet – genuinely challenging given how common soy is in processed food, which makes careful label reading essential for spotting hidden sources.
Some soy-free recipe ideas worth trying include vegetarian chilli with beans, roasted vegetable salad, or quinoa with mushrooms and spinach.
Related reading: Chickpea Allergy: Symptoms, Cross-Reactivity & What to Avoid · Lupin Allergy
