Soy Free Diet
What is soya?
The United Nations FAO (Food and Agriculture Association) classifies the soya bean as an oilseed. Known as soyabean in the USA, this edible legume is native to Southeast Asia and is cultivated widely for its high productivity (in protein produced per acre) and numerous uses, the biggest producers being the United States, Brazil, Argentina, China and India.
Soyamilk and tofu are traditional non-fermented food uses of soya beans, while some fermented foods include: soya sauce, fermented bean paste, natto and tempeh. Processing soya beans produces soya vegetable oil and soya products like texturised vegetable protein (TVP) are used in lots of meat and dairy substitutes. Leftover defatted soyabean meal can be used as a cheap source of protein in animal feed and soya oil has numerous industrial applications.
What is a soya allergy?
Approximately 17 million people world-wide suffer from an allergic reaction to protein found in soya beans, although the percentage of the population affected varies from country to country – different studies have shown figures that range between 1-5%. However, allergies to soya are more common in children (in the US it affects 4% of children) than in adults and approximately half of affected children will outgrow the allergy by the time they are seven years old.
How do I know if I’m allergic to soya?
Symptoms of a soya allergy will normally appear within a few minutes to two hours of consuming the allergenic protein and include skin rashes like eczema or hives, swollen, red, watery eyes, gastrointestinal symptoms, such as abdominal pain, nausea, diarrhoea, and/or vomiting, difficulty breathing, wheezing, or coughing and swelling of the lips, tongue, or face. A severe reaction can cause anaphylactic shock and requires immediate medical attention as it is potentially fatal.
Few infants develop a true immunoglobin-E allergic response to soya protein and it is believed that the main trigger for a soya allergy in babies who have not yet begun eating solid foods is soya-based infant formula. Symptoms will normally develop within a few months of birth (the most common being bloody stools) but babies normally outgrow the allergy by the time they are two years old. However, some babies may develop a Milk-Soya Protein Intolerance or Food Protein Induced Enterocolitis Syndrome (FPIES), which can lead to symptoms of shock. It is therefore important to seek medical advice if you suspect your baby is developing a food allergy.
Beans and peas, amongst other legumes, may cause cross-reactivity in people with a soya allergy, but this is rare. Some people with Oral Allergy Syndrome, especially to birch pollen, may have itching or swelling of the mouth, tongue, or throat after eating soya.
What does a soya-free diet entail?
Soya can be difficult to avoid, especially for vegetarians, as it is used widely in foods around the world, in its whole bean form, as soya flour, soya sauce or soya oil. Up to 60% of manufactured foods also use soya as a texturiser (texturised vegetable protein), emulsifier (soya lecithin) or protein filler.
Foods that you should always steer clear of when on a soya-free diet include miso, soya sauce, tempeh and tofu, as well as lots of vegan products like soya margarine, soya cheeses, soya yoghurts and desserts. Soya is also often a hidden ingredient in baked goods like bread, cakes and biscuits as well as pasta and pizza bases.
Anything heavily seasoned is also suspect, including: snack bars, crackers and crisps, spice mixes, seasoned salt and sauces like Worcester sauce, sweet and sour sauce, Teriyaki sauce, stock cubes, gravy powders and some ready made sauces, mayonnaise, sandwich spreads and salad creams.
Dairy and cheese substitutes often contain soya, as do dessert mixes, pancake and waffle mixes, ice cream, frozen desserts, margarine and milk (coffee whiteners) or cream substitutes. Ready meals also often contain soya, as do canned and packet soups and processed meat products such as: cold cuts, beef burgers, meat pasties/pies, minced beef, sausages, and hotdogs. This wide range means that is it extremely important to read ingredients lists very carefully when avoiding soya. Avoid anything with ‘soya’ in the name, including: soya protein isolate, soya shortening, soya protein, soya albumin, soya bean, soya flavouring, soya flour, soya gum, soya lecithin (E322), soya milk, soya nuts, soya oil and soya starch.
Any ingredient listed as ‘vegetable’ may also indicate the presence of soya, such as: vegetable broth, vegetable oil, vegetable protein, vegetable paste, textured vegetable protein (TVP), hydrolysed vegetable protein (HVP) and hydrolysed plant proteins (HPP).
A note on labelling and eating out
The FSA in the UK, the European Food Safety Authority and the Food and Drug Administration all classify soya as a major food allergen, which means that within the UK, as well as the rest of the EU and the USA, soya must be clearly listed on all food ingredients labels. However it is important to remember that foods sold in other parts of the world (whether made within the US or the EU or not), do not have to comply with these laws. Also, regulations in the US make an exception for refined soya bean oil and soya lecithin, neither being required to be disclosed in a “Contains” statement on labels. Both are commonly used as preservatives and texturisers and as ingredients in processed foods, so people with severe soya allergies need to be careful if the latter constitutes a significant part of their diet. Soya-based lecithin is often used to stabilise foods containing water and fats (which do not naturally mix), like in chocolate bars to prevent the cocoa and cocoa butter from separating. However, most people with a soya allergy can tolerate soya-based lecithin, as it is actually a fat and therefore contains very little soya protein. So the good news is that chocolate doesn’t have to be taken completely off the treats table!
Furthermore, the Food Standards Agency in the UK has advised that the process of refining soya oil removes the allergenic proteins from the oil and so refined soya oil (the main component of vegetable oil) is also generally safe to eat even with a soya allergy. However, cold-pressed soya oil, usually sold from delicatessen counters or health food shops, can contain soya protein and should be avoided. Loose bakery and delicatessen goods can also often become cross-contaminated with soya.
It is a good idea to generally avoid cuisines that traditionally cook with soya and to disclose that you have a soya allergy to the chef, as it may be a hidden ingredient in your food. For example, lots of restaurants cook in soya bean oil, since it is the cheapest vegetable oil.
What are the risks and/or advantages of going soya-free?
Soya beans contain significant amounts of isoflavines, α-linolenic acid and phytic acid, all of which impact human health.
Isoflavines are produced solely by beans in the Leguminosae family. Soya isoflavine in particular has been linked with a lower incidence of breast cancer and other common cancers because of its influence on the metabolism of sex hormone, specifically in Asian populations. Other studies have found no link between breast cancer cell proliferation and isoflavine consumption, and one large study combining data on US and Chinese women found that soya consumption of ≥10 mg isoflavones per day was associated with a non-significant reduced risk of breast cancer-specific mortality and a statistically significant reduced risk of recurrence.
A-linolenic acid is an essential fatty acid that has been linked to decreased risk of cardiovascular disease, as well as lower anxiety and stress levels. However there are other natural sources of α-linolenic, such as walnuts, and especially in linseed and linseed oil.
Phytic acid is sometimes considered a phytonutrient and antioxidant, but it also binds with important minerals, such as calcium, iron, and zinc. Vitamin C can reduce phytic acid’s affinity for calicium, but iron and zinc become insoluble when they bind to phytic acid making them harder to absorb through the intestines. In this regard, soya acts as an antinutrient and a soya-free diet can have beneficial effects on health, especially for people whose diets are low in essential minerals. In developing countries where soya is a major source of protein it is thought to contribute towards zinc and iron deficiencies. The acid effects have also been linked to pellagra, a deficiency of the vitamin niacin.
Eating soya-free as a vegetarian can be tricky, as it is often a major source of protein in vegetarian diets, and a lot of processed vegetarian foods include soya. However, whole grains, legumes, and dairy products can easily meet your protein requirements and provide a balanced diet.