A Controlled Trial of Immunotherapy for Asthma in Allergic Children
What Does An At-Home Food Sensitivity Test Tell You? I Tried One To Find Out
A cruel irony to being a food and travel writer is that I often suffer from stomach problems. My IBS (previously a colitis diagnosis) can turn any grand tasting into a terror with cramping, bloating, and, well, I'll spare you the more graphic details.
Though I've never tested positive for major food allergies or intolerances including gluten (a common culprit) or dairy, I've always wondered if I had any sensitivities that I was unaware of, especially as someone who eats everything and anything at any given moment.
Joey Skladany/CNETEnter Everlywell: The $199 at-home food sensitivity kit measures your body's immune response to 96 common foods.
"At-home lab testing for IgG (short for the responsive antibodies called immunoglobulin G) reactivity can be a great way for those with relatively mild, food-related symptoms to start their journey to feeling better," says Dr. Gabe Gaviola, MD, MPH, senior medical director at Everlywell.
"Traditional temporary elimination diets are highly restrictive and can provide massive disruptions to someone's normal dietary routine. By identifying the most likely candidates for problem foods, the Everlywell Food Sensitivity Test helps take the guesswork and dietary disruption out of a traditional elimination diet."
While there are mixed opinions on using IgG levels as a marker for food allergies, intolerances or sensitivities, curiosity got the best of me (as it usually does) and I decided to order the test and assume the role of guinea pig.
Here's how it all went down.
Note: As with any health condition, please always seek the guidance of a licensed medical professional for proper diagnoses.
How the Food Sensitivity Test Works Joey Skladany/CNET"The Everlywell Food Sensitivity Test was developed using an immunoassay platform, which selects certain food isolates," explains Gaviola. "The test measures someone's IgG antibody response to these foods. IgG is an antibody that is separate from conditions such as food intolerances or food allergies."
"Research suggests that for some individuals, higher IgG immune responses to specific foods may mean those foods are more likely to cause uncomfortable GI symptoms, including nausea, bloating, GI upset, and abdominal pain," he adds.
While more evidence is needed on IgG to make sweeping generalizations about its relationship to food sensitivities, Everylwell believes that they can provide a base level understanding of why people's guts react the way that they do. This isn't meant to be a diagnosis, by any means, but rather something to consider as you identify potential gastrointestinal triggers.
My Unique Stomach Issues Wilted greens are murder on my stomach. HUIZENG HU/Getty ImagesAside from overly rich foods, wilted greens, and wine consumed in excess, there aren't many ingredients that bring on immediate bouts of indigestion. Most of my stomach issues, according to my gastroenterologist, are either hereditary (my grandmother has severe colitis) or anxiety-induced.
That said, there are two fruits that often cause physical reactions while eating: apples and avocados. The former makes my lips tingle and swell up, which may be more of a pesticide on skin problem, and the latter makes me instantly nauseated when consumed as slices on sandwiches or chunks in a salad. Oddly enough, guacamole has zero effect on me.
The Food Sensitivity Test Process Everything you need to test food sensitivity at home. Joey Skladany/CNETWhile nobody enjoys pricking their fingers to draw droplets of blood, the testing process could not have been more straightforward and simple.
Each kit comes with instructions and the instruments needed to execute the test. This includes a collection card, alcohol prep pad, lancets, biohazard bag, gauze, bandage, return envelope and a return label.
An abbreviated sequence of events:Results typically take about a week or two and can be accessed online (where you'll register your unique kit ID upon receiving it).
Here's what the test results said I eat chicken as much as anything and it never seems to upset my stomach, despite Everywell's analysis. Kseniya Ovchinnikova/GettyLuckily for me, nothing came back higher than mild reactivity. And out of the 98 foods tested, I only had elevated IgG levels for eight: black tea, chicken, chickpea, eggplant, garlic, grape leaf, pomegranate and sunflower seed.
These results were equal parts surprising and hilarious -- surprising because I have never noticed a GI reaction to any of them and hilarious because I received these results while on vacation in, wait for it, Greece! Needless to say, I was eating a *lot* of literally every ingredient that may have been causing digestive distress.
Oddly, there was no indication that the aforementioned apple or avocado would lead to any type of immune response. I can't assume that they don't negatively affect my body, but I would have guessed that they'd be at the top of the results document.
What to do after results An elimination diet will help determine if the foods isolated are indeed a cause of GI distress. David Watsky/CNETAside from providing article resources and answers to nearly a dozen common questions, Everlywell suggests five next steps to continue your stomach health journey:
Remember, the Food Sensitivity Test does *not* test for food allergies and should not be used for this purpose.
"The results from the Everlywell Food Sensitivity Test are not diagnostic and are only meant to help identify top foods for someone to prioritize in a temporary elimination diet," adds Gaviola.
Food sensitivity test accuracy The food test instructions were crystal clear, but the results didn't align with my history of distress. Joey Skladany/CNETAs research appears to be conflicting, Gaviola is the first to remind customers that, again, any type of food allergy can only be diagnosed by a doctor.
"The tests measure totally different biomarkers and only a healthcare provider or allergy specialist is able to diagnose a food allergy, " he stresses. "Everlywell also recommends against any allergic reaction food trials that do not take place under the observation and direction of an allergy specialist."
Additionally, while testing companies like Everlywell operate in accordance with clinical guidelines and CLIA-certified laboratories, they are the first to advise speaking with a licensed healthcare provider.
Final thoughtsWhile I'm certainly not planning to eliminate chicken and hummus from my diet and don't have any evidence to support those foods being an issue for my stomach, the test did give me something to think about. In fact, I plan to use some upcoming travel downtime to eliminate these foods temporarily and see if they make a difference. It can't hurt, right? And at the very least, it certainly won't hurt as much as a debilitating stomach cramp.
Could A DNA Diet Test Transform Your Health?
by Sue Quinn
The number of home DNA test kits offering nutrition and diet advice matched to your genes is growing. They're based on the idea that each of us responds to foods differently, in part due to our unique genetic make-up, so we have individual nutritional needs. But the science is emerging and there are calls for greater regulation of the industry. Could tailoring your diet to your genes help you optimise your health?
The concept has been around since scientists finished mapping the human genome almost 20 years ago. But recently DNA tests have become cheaper, quicker and more available to use at home. They are sometimes known as direct-to-consumer genomic tests. Different kinds of tests can be bought, including kits for exploring your ancestry and assessing your risk of developing certain health conditions.
Nutrigenomics tests are designed for nutrition and diet, and are offered by many companies, including Nutri-genetix, DNAfit and 23andme. You order your kit online, post back a saliva sample or cheek swab, and your DNA is screened to find out whether you carry genetic variations linked to certain food responses. The tests vary, but often they assess your risk for conditions such as lactose intolerance and coeliac disease, and sensitivities to things like coffee, alcohol, carbohydrates, fat and salt. The report you receive back might include advice about foods to eat or avoid, how to lose weight or manage your weight, and your requirement for certain vitamins and nutrients.
How do the tests work?In nutrigenomics tests, your DNA sample is screened for small variations in a limited number of specific genes associated with particular food responses. These associations are based on the findings of population studies into whether people who react in a certain way to particular foods have gene variations in common. As such, nutrigenomic tests assess your predisposition to certain food responses. For example, depending on your genetic profile you may metabolise carbohydrates more quickly than average. In theory, you can then adjust your diet to manage spikes in your blood sugar.
But if a test finds you're likely to react to nutrients in a certain way, it doesn't mean you definitely will. "Genetic predispositions are exactly that", says Dr Keith Grimaldi, Chief Science Officer of DNAfit. "Certain variants will affect the likelihood of a certain outcome."
Like most DNA testing companies, DNAfit screens for gene variations where there is "a reasonable level of scientific consensus, based on human studies" they will have a particular effect. Dr Grimaldi says if you carry the genetic variation CYP1A2 (AA), for example, you will "almost certainly" metabolise caffeine faster than someone who doesn't, and therefore feel its effects more strongly. It's also likely people with variations of the MCM6 gene will tolerate lactose, the sugar found in milk.
Image caption,DNA tests are sometimes used to check for lactose tolerance.
DNA tests help reduce and manage obesityDNA testing is being used successfully in research projects to treat people with a genetic predisposition for obesity, according to Vimal Karani, Professor in Nutrigenetics and Nutrigenomics at the University of Reading.
Variations in the FTO gene, also known as the 'fat gene', are strongly associated with a higher risk of obesity, particularly among certain ethnic groups. Research shows those who carry at least one copy of specific FTO variations, and who eat a high-carbohydrate diet or are physically inactive, are at 'particularly high risk' of obesity.
Carrying these variations does not seal your fate though, Dr Karani stresses. His research in low-income countries suggests adopting a healthy high-fibre diet and increasing physical activity could reduce this genetic risk. "There are several genetic testing centres in these countries successfully prescribing personalised diets for people to prevent and reduce obesity", he says.
With less than five percent of the genetic variations responsible for obesity identified so far, research in the area is still in its infancy, says Dr Karani. What's more, your genes are only part of the complex system involved in your body's response to food. "DNA tests are just part of the equation", he says. "An array of other biological markers need to be analysed too, including gut microbiome, metabolites (chemicals involved in bodily functions), blood sugars and fats, cholesterol, blood pressure and lifestyle factors", to complete the picture.
Image caption,Obesity genes have been identified, and some DNA tests check for these.
Do DNA home test kits work?But we currently have limited knowledge about the interplay between genes, nutrients and health, according to Dr José Ordovás, Director of Nutrition and Genomics at Tufts University in Boston. There are millions of genetic variations in human DNA, and scientists still don't know how the vast majority of them influence the way the body functions, or how one gene variation affects another. "For many of the traits DNA kits are testing for – sensitivity to fats and coffee, Omega-3 requirements and the like – there are scores of genes involved", argues Dr Ordovás. "The genes they're testing for are just the tip of the iceberg."
Studies carried out by researchers from King's College London, Massachusetts General Hospital and nutritional science company ZOE, show even identical twins can process the same foods differently, which suggests factors in addition to genetics are important for at least some conditions. "Environmental factors have a profound influence", says Dr Ordovás – "the time we eat, our stress levels, what we did the previous day, the season of the year, and of course, our microbiota [the organisms in our gut known to impact health]".
But nutrigenomic tests might motivate some people to improve their diet, according to Dr Ordovás. "If you follow the recommendations of one of these diets it may benefit you… but that's not necessarily because it's exclusively tailored for you. It may be because you change your eating habits for [the] better."
Image caption,Environmental factors, such as sleep, stress and gut bacteria, in addition to genes, have been found to influence our responses to food.
DNA tests of the futureDr Virani believes nutrigenomic testing will become more meaningful when combined with other data about your individual digestive and metabolic processes: biological markers (such as blood sugar and fat), metabolites (the molecules involved in your metabolism) and gut microbiome (the gut bacteria).
Health science company ZOE have launched an at-home test kit in the UK that analyses your gut, blood fat and blood-sugar responses to food. And some DNA test companies offer blood tests as an add-on to their genetic tests. But there is still much work to be done to help us understand the complex factors that affect our unique responses to food, and how to combine all the information into algorithms that generate useful tailored dietary advice.
Dr Virani envisages the day when precision nutrition, including nutrigenomic tests, will play a key role in improving the nation's health. "If solid evidence is available that these precision nutrition approaches can reduce the prevalence of obesity and other chronic diseases, the government and the NHS should make these tests available free of charge to everyone", he says. But he considers this "a long way off".
In June 2021, a Parliamentary Committee published its first report into direct-to-consumer genomic testing. It urged the Government to require manufacturers to have the performance of DNA tests "assessed by an external body" before putting them on sale in the UK, to ensure they're reliable and deliver the promised results. The government responded in November 2021 explaining they would be investigating further
Originally published June 2021
Specificity, Sensitivity And Cost
Cite this articleSpecificity, sensitivity and cost. Nat Rev Cancer 7, 893 (2007). Https://doi.Org/10.1038/nrc2287
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