Soy

What a soy allergy is

A soy allergy is a reaction to the proteins in the soybean, Glycine max — a legume, and so a relative of the peanut, lentil and chickpea rather than of any grain. The soybean is unusual among allergens in how completely it has been taken apart by industry. It is crushed for oil, the residue is pressed into meal, the meal is spun into protein isolates and texturised into meat substitutes, and the oil yields lecithin, tocopherols and sterols as by-products. Each of those fractions carries a different amount of protein, and some carry effectively none, which is why soy is the allergen with the longest list of formal exemptions.

That industrial reach also means soy appears in food that has nothing to do with East Asian cooking. Bread and buns, chocolate and chocolate coatings, margarine and spreads, tinned tuna, stock cubes, sausages and burgers, infant formula, protein bars, and almost anything breaded or fried commercially.

The names that do not say “soy”

Soya is the British and European spelling, and soja is the word on French, German, Spanish, Dutch and Polish labels. Both are the same bean.

Edamame are immature green soybeans in the pod. Tofu and bean curd are curdled soy milk. Yuba is the skin that forms on heated soy milk, dried and sold in sheets. Okara is the pulp left after straining soy milk, used in burgers and biscuits.

The fermented names are the ones that never spell out the bean. Miso is fermented soybean paste. Natto is whole fermented soybeans. Tempeh is a fermented soybean cake. Shoyu is Japanese soy sauce, and tamari is a soy sauce traditionally brewed with little or no wheat — worth knowing, because tamari is often marketed to people avoiding gluten and is still entirely soy.

Textured vegetable protein, usually abbreviated TVP, is defatted soy flour extruded into chunks or mince. Soy protein isolate and concentrate are the purified forms, added to bars, shakes and processed meat.

Hydrolysed vegetable protein names no vegetable at all; soy is one of the common sources, so the term is a question rather than an answer. Mono- and diglycerides are emulsifiers that may be made from soybean oil among other fats, and the source is not usually given.

Soy lecithin, additive number E322, is the single most widespread soy derivative in the food supply.

How the label is worded where you are

In the EU and UK, soy must be emphasised inside the ingredient list, normally in bold, so lecithin has to be shown as soy lecithin rather than left as E322. Four soy-derived items are named exceptions and are exempt from allergen declaration altogether: fully refined soybean oil and fat; natural mixed tocopherols (E306) and the natural D-alpha-tocopherol, acetate and succinate forms derived from soy; phytosterols and phytosterol esters derived from soybean oil; and plant stanol esters made from soybean oil sterols. Those are the ones that can be present without the word soy appearing anywhere.

In the United States the plain word soy must appear in the ingredient list or a “Contains” line, and the statute excludes highly refined oils from the definition of a major allergen, so refined soybean oil needs no declaration there either. Elsewhere you may get only soja or a fermented product name, mid-list, with no emphasis.

Cross-contamination and “may contain”

Soy is handled in bulk, and soy flour and protein powder are dusts, so shared bakery and snack lines carry it readily. Chocolate plants, which run lecithin through almost everything, and fryers using blended vegetable oils are the two places precautionary labelling shows up most. “May contain soy” and “made on equipment that also processes soya” are voluntary and unstandardised in most jurisdictions, and no phrasing is legally safer than another; the absence of a warning is not evidence that no soy came near. Loose bakery items and deli counters carry no list at all. PNut reports any such wording as May contain rather than resolving it one way or the other, and what “may contain traces” actually means covers how those lines get onto a pack in the first place.

Reading a soy label abroad

The base word travels well: soja, soya, soia, soya fasulyesi are all recognisable, and 大豆 and 黄豆 are consistent across Chinese labels. The trouble is the product names. A Japanese or Korean label may list 醤油 or a romanised shoyu with no separate mention of soybean, and European labels frequently print lécithine de soja or Sojalecithin as a single compound word that scans past the eye as an additive. The table below gives the bean, the lecithin and the sauce for each language; reading a label in a language you don’t speak covers finding and working through the list itself.

How PNut flags soy

Scan the barcode and PNut looks up the product’s published ingredient list; photograph the ingredient panel and it reads the text off the label instead, in any of 40+ languages. It checks for soy and for every derivative and fermented name on this page, then gives one of four verdicts — Safe, Contains allergen, May contain, or Unknown when the label cannot be read. An unreadable or incomplete label returns Unknown rather than a guess.