The Nima gluten test – can it be trusted?

Alex Gazzola reviews the Nima Sensor gluten tester.


It caught many by surprise when Nima turned up as exhibitors at the Free From Show Winter on the 3rd November last year. The US-based science tech company, who launched their Nima Sensor gluten tester onto the American market in January 2017, were in Liverpool to bring their elegant black table-top gadget to British shores too, via their European distributors, ALK.

Claiming to help users ‘to be their healthiest selves by giving them the power to know what’s in their food’ and promising them ‘peace of mind at meal time’, the Nima Sensor for gluten is, no doubt, a nifty bit of kit.

The portable sensor is designed to accept pea-sized samples of foods, inserted within single-use capsules, and to then test for the presence of gluten within them. The chemistry is complex, but involves an antibody system within the capsule that binds to the notorious 33-mer gliadin protein chain of gluten. If this happens – that is, if sufficient gluten is present to enable it – the bound antibody-gluten complexes will be detected by the sensors.

Are there any limitations?


Some forms of gluten cannot be detected or tested; these include fermented or hydrolyzed products (soy sauce, beer, malt vinegar) and alcoholic drinks, plus gums (xanthan, guar) and brightly coloured foods. Given the widespread use of soy sauce as a flavour enhancer, and the potential interchangeability of Chinese soy sauce (usually wheat containing) and Japanese soy sauce (usually gluten free) in a kitchen, perhaps by chefs unaware of the differences, this is a significant issue.

It does not detect (gluten free) oats, which around 5% of coeliacs may have to avoid; but does detect oats contaminated with, for example, wheat flour.

Further, potential gluten contamination in a meal may be unevenly distributed within it, meaning any pea-sized sample is unlikely to be representative of the whole, unless it is a blended soup, for example. Particulates can be missed.

To in part mitigate against this obvious problem, Nima say “you can take small samples of everything on your plate and put them into a single capsule” but in the event of a positive finding, you won’t know where the gluten is lurking. Multiple tests are also suggested as a possibility, but at three minutes per test and $5 per capsule, this is likely to be costlier than the food on your plate which is rapidly getting cold.

What does the Nima tell you?

Unless there is an error and the testing capsule fails, the sensor provides one of two results to each sample testing. Either:

a/ ‘gluten found’, or

b/ an image of a smiley face — which, according to the manufacturers means “Either no gluten detected or gluten detected below 20 parts per million [20ppm]” (That is, gluten free, to all intents and purposes, according to UK, EU and North American GF standards).

How accurate is it?

The million dollar question.

Nima has always been very keen to promote its sensor as accurate, but meaningful validation data was until recently thin on the ground.

Arguably the first important figures were made available in early 2018, conducted by the Nima team themselves. The study, now published in the journal Food Chemistry, involved testing gluten-free food samples (e.g. breads, cake, burgers, ice cream, soup) both before and after spiking them with 20ppm of gluten, as well as a selection of food samples purchased from restaurants and grocery stores, and comparing the results to independent laboratory tests of the same samples. On the face of it, the results seem very good, and the key take-away result from this study is that the device is 96.9% accurate.

However, there are particular problems with the derivation of this figure and what ‘accuracy’ means in this context, which you can read more about on the Allergy Insight blog.

The study also fails to represent most foods typically encountered in ‘real life’ consumer situations: a food sample spiked with precisely measured lab-grade gluten, for instance, is not what would be encountered at your local burger joint.

Independent validation

Despite Nima claiming as early as 2015 during their pre-launch phase that they wouldn’t release the gluten sensor before third-party validation was published, this validation was not made available until September 2018, but provides a clearer insight into the problems concerning the gadget, its use, and data interpretation.

Although funded by Nima, this independently conducted evaluation of the device came via the Food Allergy Research & Resource Program at the University of Nebraska-Lincoln, the results of which were published by the Journal of Food Protection.

Again spiked samples, this time using wheat flour, were used. The samples were three types of bread, three types of pasta noodles, salad dressing, chocolate, corn puffs, ice cream, meatballs, muffins and oatmeal. These samples were spiked with levels ranging from 5ppm to 100ppm of gluten.

The researchers reported that almost 95% of food samples at 20ppm and above were reporting ‘gluten found’ on the Nima. A good result, on the surface, although at 20ppm itself, that figure was 80%.

But there were notable failures on certain samples. As the researchers wrote:

“At the critical level of 20ppm, the Nima device failed to detect gluten in any of six samples of pasta brand A, in three of six samples of bread brand A, and in three of six samples of corn puffs.”

This suggests certain samples / ingredients may evade effective extraction in the Nima, though in fairness, the performance at 30ppm and 40ppm of these particular samples was very good in reporting ‘gluten found’.

Overall, there were also problematically unreliable results in the middle-range of the gluten-free ‘zone’. Over half of tested samples of prepared food at 10ppm – safely within official gluten free levels – returned ‘gluten found’. 30% did likewise at 5ppm.

The concern here is that consumers would likely refuse these safe foods, and unfairly register a ‘gluten found’ mark against the food service provider via the app to which the Nima can be linked, and results of which are collated into a database which consumers can access.

Nima’s defence here is that any gluten found is worth reporting. As the CEO Shireen Yates has said, “Nima wants to protect you from accidentally consuming gluten at any level – not just 20ppm …”

But this can lead to alarm …

The restaurant study

In early October, some of the ‘real’ reported data from US Nima customers was collated, analysed and published in a paper written by Columbia University scientists and Yates.

It recorded that one-third (32.2%) of restaurant foods tested gave a ‘gluten found’ result in Nima testing.

This finding was represented in the study as “One-third of restaurant foods labeled GF contained at least 20ppm of gluten”.

And yet this conclusion is quite wrong. By Nima’s own admission, and as well as the independent validation figures discussed above, a ‘gluten found’ result periodically occurs at 5ppm and half the time at 10ppm, much lower than 20ppm and technically gluten free. The Nima is not a quantifiable test, so statements about gluten content cannot be drawn from any single or multiple results it provides.

The ‘one third’ claim was widely reported throughout the American media, including the New York Post, and many others, and caused concern among the celiac community. Despite justifiable requests by dietitian Tricia Thompson, who runs independent food testing agency Gluten Free Watchdog, and who is a critic of the Nima, three months on, at the time of writing, the paper remains uncorrected. Thompson has also pointed out that she considers the Nima not yet scientifically validated, and therefore unsuited to determining cross-contamination in restaurant settings, which surely undermines the whole premise of the research.

In summary

For its part, having previously stated it could not recommend the sensor, Coeliac UK has now taken a more neutral approach based on informed choice in guidance to its members. The charity has emphasised its limitations, and advises coeliacs to always ask for more information on food preparation.

“Some report the Nima of use, so we set out how tests work so people can decide on the right tool for them,” said the charity recently. “Checking ingredient lists and asking about how dishes are made overall is the surest way to assess safety.”

The Nima undoubtedly has its fans, with many arguing that it has empowered them and helped them to feel safer when eating out.

But there appears to be no escaping an awkward truth: when the sensor provies a ‘gluten found’ result, it doesn’t specify whether that’s over or under 20ppm, therefore whether it’s safe or not for those with coeliac disease according to official guidance.

How useful can that information be?

The Nima Gluten Sensor is available in the UK for £189.99 for the gadget and 12 capsules, which cost £59.99 separately.

January 2019

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