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For people who have celiac disease, it is well-established that gluten is the problem. For people who think they have “non-celiac gluten sensitivity (NCGS),” however, it has not been clearly established that for all individuals it is always the gluten in gluten-containing foods that is the problem. Generally, NCGS is diagnosed by ruling out other conditions which may be causing the symptoms, and then seeing if a gluten-free diet improves symptoms. Things get murky because in a gluten-free diet, other dietary components are also potentially reduced.
Fructans come into play because some gluten-containing foods also contain fructans: wheat, for example. (Fructans are found in various other foods too, including onion and watermelon.) So, when you go on a gluten-free diet you may also be reducing fructans. Some research has indicated that individuals who think they are gluten sensitive are in fact reacting to fructans (https://www.ncbi.nlm.nih.gov/pubmed/29102613). This is a good example of why it is important to work with your healthcare team and a knowledgeable dietitian if you believe you are gluten sensitive, in order to explore and rule out other possible conditions.
Theoretically a tap line should be flushed and cleaned before a new item (e.g. gluten-free beer or cider) is put into it, but there are no standards to follow and no guarantee that this happens. If you want to pursue having a gluten-free drink from a tap, ask the staff questions about what was in the tap line previously, and whether it was thoroughly cleaned before the gluten-free beverage was put in. You’d need to use your judgement as to how confident these answers make you feel. The best option is to order bottled drinks rather than from a tap.
It is possible for a certified gluten-free product to contain wheat, but the wheat would need to be processed to remove all protein. An ingredient like wheat starch would be the most common example, and the ingredient would need to be tested to ensure that it meets our 10 ppm threshold.
“May contain” or “shared equipment” statements are voluntarily included on some products to alert wheat allergic consumers of the presence of wheat in a manufacturing facility, because people with wheat allergies can have a reaction to wheat fractions other than gluten, and there is no test available to detect these other fractions. The presence of wheat starch as an ingredient would be an example of where you might see a “Contains: Wheat” statement alongside a gluten-free claim. For purposes of choosing gluten-free products, these types of statements are not relevant. If you see this type of statement on a product that is certified gluten-free, the gluten-free labeling/certification means that it is gluten-free regardless of any “may contain” type statements and contains 10 ppm gluten or less.
Unfortunately there are no supplements or medications which “neutralize” or “de-activate” gluten. Research is going on in the scientific community on substances that may make it less problematic to consume very small amounts of gluten, such as what might be ingested due to cross-contamination. A gluten-free diet is currently the only treatment for gluten-related disorders.
It is important if you think you have gluten sensitivity, that you are checked for other conditions that might cause your symptoms. There is no specific diagnostic test for gluten sensitivity. So, it is important that other possible causes of symptoms be looked into as well (including celiac disease, and possibly intolerance to other substances in gluten-containing foods, such as “FODMAPs”).
Yes, it’s possible. Just as for other foods, it’s always important to read labels, and avoid bulk bins. It is not uncommon for date pieces in particular, to be coated in oat flour to prevent sticking. Oats should be avoided unless certified gluten-free and oat flour used for this purpose is not likely to be gluten-free (again, though, read labels, as a gluten-free oat flour could be used.) Most other dried fruits are gluten-free.
This is somewhat of a judgement call, and depends on how these items are being used. If a pot holder is being used on a gluten-containing fruit cobbler, for instance, and the cobbler rises up to or over the top of the baking pan, there’s a chance the pot holder may inadvertently come in contact with the food. If a bit of gluten is on the pot holder and you later use it in the same way on your gluten-free cobbler, cross-contact could result. On the other hand, if sufficient care is taken to be sure that the pot holder does not come into contact with the food, you should be o.k. Consider the type and amount of gluten-containing items being made in your kitchen. It may also be reasonable to expect that younger children or others with less understanding of your dietary needs may not be as vigilant about avoiding cross-contact as you are.
Regarding dish towels, much of the same applies. If your family members are using kitchen towels only on dishes or hands which have been thoroughly washed, you should be o.k. Otherwise, separate towels, or paper towels are a good idea.
Luckily for gluten-free consumers these days, there are currently a number of excellent gluten-free flour blends on the market. Gone are the days when it was necessary to purchase multiple flours and mix up your own blend at home, leaving you with numerous partially used bags of gluten-free flours and nowhere to keep them (of course, mixing your own blend is still an option if you are so inclined). While many of these flour blends can be used as a direct substitution for wheat flour (often with the addition of xanthan or guar gum), this doesn’t mean that the results will be identical. Gluten-free baked goods can be absolutely delicious, but the flavor and texture vary from their wheat flour-based versions. So, if you have family favorites which you want to convert, be open-minded. Choose a gluten-free flour blend (or make your own) and start with recipes which contain smaller amounts of flours (e.g. nut tortes, fruit crisps). When flour is a less major component of the dessert, any flavor and texture difference related to the gluten-free substitution will be smaller. Give yourself some time to adjust to the modified results which will result from using gluten-free flours. As you get more comfortable with gluten-free baking, experiment with recipes which rely more on flour. Another approach to gluten-free baking is, of course, to use recipes which simply don’t call for any flour to start with: for example flourless chocolate cake, french macarons, (flourless) peanut butter chocolate chip cookies, and meringues. And finally, don’t forget to explore the world of gluten-free baking which takes advantage of delicious and nutritious gluten-free flours which you may never have explored before, such as teff, buckwheat and sorghum.
GERD (gastroesophogealreflux disease) occurs when a muscle at the end of the esophagus does not close properly and allows stomach content to go back up into the esophagus. This backwash (or reflux) irritates the lining of the esophagus, causing symptoms which include heartburn, a sour taste in the mouth and nausea. Some research has indicated that GERD symptoms may occur in untreated or newly diagnosed celiac disease.
There is a genetic linkage between celiac disease and other associated autoimmune diseases. While the prevalence of autoimmune disease in the general population is approximately 3%, about 14% of people with celiac disease have an additional autoimmune condition. Those most commonly associated with celiac disease are type 1 diabetes and autoimmune thyroid disease.
Since flatbreads don’t depend on yeast and rising the way most traditional loaf breads do, you are right, they are by nature more compatible with gluten-free baking as long as they are made from gluten-free grains. Flatbreads (and related crepes or savory pancakes) are traditionally consumed in many parts of the world. While some are made of wheat flour, many are made from gluten-free grains. Here are a few delicious options to investigate and try, whether in your own kitchen or when eating out.
And don’t forget about corn tortillas: widely available and especially delicious when freshly made.
The vast majority of ice creams are inherently gluten-free. The basic ingredients are usually milk, cream, sweetener(s) and flavorings (e.g. fruit, chocolate, etc.). As with any other product, it is always important to read ingredient labels (on packaged items) and ask questions (in restaurants /ice cream shops). Flavorings could contain gluten and need to be verified. Many popular ice creams contain obvious gluten-containing ingredients such as cookie or brownie pieces, but that’s not all you need to be mindful of. If you’re at an ice cream shop which serves cones, you’re not always safe simply requesting your scoop in a dish instead of a cone. When previous cone orders were filled, the same utensil used to serve your ice cream may have been used to push a scoop onto a cone, possibly resulting in cross-contact with the cone. This potentially contaminated utensil may then go back into the ice cream container and transfer cone crumbs into the ice cream. Explain your situation to your server; there is nearly always product in the back which has not yet been tapped into, and which would therefore be free of any possible cross-contamination.
If you use a shared kitchen or eating space at home, work or school, you could inadvertently be ingesting gluten. Remember, even a crumb of gluten-containing bread can be enough to cause problems for people with celiac disease or gluten sensitivity. Consider washing table tops with soap and water, or putting a barrier (e.g. paper towel) between your food container and the table top to avoid picking up hard-to-see crumbs. Also, don’t forget that your partner or children who eat gluten may need to brush their teeth before you share kisses. Finally, washing your hands with soap and water before preparing and eating any food will help you stay gluten-free, and healthy.
Many restaurants now offer gluten-free options, which is exciting for those of us in the gluten-free community. Unfortunately, not all staff in those restaurants is necessarily aware of the importance of gluten-free ingredients and of strict avoidance of cross-contact during food preparation. Furthermore, some restaurants offering “gluten-free” menu options may not have necessary procedures set up to allow for reliable production of gluten-free items. When possible, do some research in advance: call or visit the restaurant during a morning or afternoon when restaurants tend to be less busy. Ask how gluten-free items are prepared and what procedures are in place to avoid cross-contact between foods that contain gluten and those intended to be gluten-free. You can then make an informed decision as to whether or not you feel comfortable dining in the establishment.
The short answer is no, since the FDA gluten-free regulation applies to food products, not to advertising. A distinct government agency regulates truth in advertising: the Federal Trade Commission (FTC). The FTC website (www.FTC.gov) states: “When consumers see or hear an advertisement, whether it’s on the Internet, radio or television, or anywhere else, federal law says that ad must be truthful, not misleading, and, when appropriate, backed by scientific evidence. The Federal Trade Commission enforces these truth-in-advertising laws, and it applies the same standards no matter where an ad appears – in newspapers and magazines, online, in the mail, or on billboards or buses. According to the agency, if a consumer believes that an advertising claim is false or misleading, this can be reported to the FTC, and the agency may proceed to conduct an investigation. Although not specified, it is reasonable to expect that if the FTC were to investigate a “gluten-free” claim, the same standard for gluten-free would be used by the FTC as the FDA (< 20 ppm). It is important to remember that the FDA gluten-free labeling regulation does not take effect until August, 2014.
Both xanthan gum and guar gum are commonly used in gluten-free baking to provide some of the properties otherwise delivered by gluten, improving texture and adding elasticity to gluten-free baked goods. Guar gum comes from the guar bean seed (originally of Asian origin); xanthan gum is the result of bacterial fermentation of carbohydrates from various sources. Alternative ingredients which offer some of the same characteristics are chia seed and psyllium husk. More and more gluten-free recipes as well as packaged foods are now utilizing these ingredients.
If you were eating products that were contaminated with gluten at some ppm level greater than zero, then it’s true that the more of those products you ate, the more gluten you would be ingesting. A study from the University of Maryland Center for Celiac Research showed that celiac patients consuming 10 mg of gluten per day for 90 days had no signs of villous atrophy. Using 10mg per day as a safe threshold, a person would have to eat half a kilogram (1.1 lbs.) of product contaminated at 20 ppm to reach that 10 mg mark during the course of a day. If you were consuming a GFCO certified product, contaminated right at the GFCO threshold of 10 ppm, that food volume goes up to a full kilogram (2.2 lbs.) to get to 10 mg of gluten. Keep in mind that most gluten free products don’t have gluten levels anywhere near those thresholds, and you can see that it would take quite a bit of eating to exceed 10 mg of gluten per day.
Most natural flavors are safely gluten-free, but some caution is called for. If you see “natural flavors” in the ingredient list of a product that is not labeled or certified gluten-free, it could contain malt extract, so should be avoided unless it can be confirmed that this is not the case. If a natural flavor contained wheat, it would have to say so (in FDA-regulated products).
Yes, flour may be used in processing, but FALCPA (the Food Allergen Labeling and Consumer Protection Act) says that all processing aids and ingredients that are allergens must be labeled. So now manufacturers cannot use wheat flour on a candy line to prevent sticking without stating it as an ingredient. Be sure to read ingredient labels carefully.
The word “malt” in both of these causes confusion, since malt usually comes from barley, which is not gluten-free. However, both of these substances are gluten-free.
Maltodextrose is a type of sugar (and therefore is gluten-free). Maltodextrin is a thickener, flavor enhancer, or filler which can be derived from a variety of starches, including corn, potato, rice or wheat. Even when it is derived from wheat it is so highly processed that it is gluten-free.
No, it just sanitizes it. Sanitation and cleaning are not the same thing. Sanitation makes it “sterile;” thorough scrubbing with soap and water removes it.
Wheat grass is a wheat product, but it is the stem of the plant. If wheat grass is harvested before the flower head builds, it is just carbohydrate and is gluten-free. However, when the plant starts to mature, it’s a problem. It is best to avoid wheat grass unless you are certain of its gluten-free status.
Find out if there is a dedicated fryer used only for gluten-free foods. Ask to see an allergen list. Ask about sauces: dark sauces may contain worcestershire-type sauce or soy sauce, both of which may or may not be gluten-free. Sauces may also be made from soup bases, which are often not gluten-free, or thickened using wheat flour. It’s also important to ask about marinades and seasonings. Ask whether the grill used for gluten-free foods is clean or shared; a good option is to ask that your food be cooked in a separate pan. Also, poached or soft-boiled eggs are a good choice (as they come in their own non-contaminated container!)
Some interesting comparisons:
This varies person by person, and also depending on how much gluten was ingested.
Here are some tips for you:
Vitamin E is gluten-free. Confusion can arise because it is sometimes derived from wheat germ oil. However, the oil is highly processed and is free of gluten protein.
Spices are still an area of concern for both gluten and allergens, but the American Spice Trade Association is working hard to clean up the spice industry, and is focusing on allergens and gluten. It is fortunate that spices are typically used in very small volumes, so the risk they present is reduced, but we recommend choosing spices that are labeled or certified gluten-free when possible.
Personal care products are not part of the FDA gluten-free labeling regulation (note that dietary supplements ARE covered in the regulation). Individuals on a gluten-free diet don’t need to be concerned about gluten in products applied to the skin (e.g. lotion, shampoo), since the gluten protein is too large to be absorbed through the skin. It is of course possible to have skin sensitivities to other ingredients in personal care products.
A product that is “inherently” gluten-free is one that is naturally gluten-free as part of its basic nature. See question above regarding labeling of naturally gluten-free products.
Yes, the manufacturer must ensure that any potential cross-contact results in a product with less than 20 ppm gluten
(or with no more than 10 ppm gluten for a GFCO certified product).
Meats and eggs are naturally gluten-free and safe to consume, regardless of whether or not the source animal consumed gluten-containing grain.
Due to risk of cross-contact, lentils should be either certified or labeled gluten-free. Organic status is unrelated to gluten-free status, so this recommendation applies equally to organic lentils.
Yeast extract in products certified or labeled gluten-free is safe for gluten-free consumers. In products which are not either certified or labeled gluten-free, note that some yeast extracts may indicate that they are grown in barley, and should therefore be avoided.
Nutritional yeast is gluten-free (as is baking yeast). The only type of yeast to be concerned about is brewer’s yeast, which may be derived from beer.
Most vinegars are gluten-free; they are distilled and are made from gluten-free ingredients (e.g. grapes). The only vinegar which needs to be avoided is malt vinegar. Malt vinegar is not distilled, and malt is derived from barley, which is not gluten-free. If you see the term “vinegar” in the ingredients list of a product which is certified or labeled gluten-free, it is safe to consume. On products which are not certified or not labeled gluten-free, the general term “vinegar” could mean malt vinegar and the product should be avoided unless it can be confirmed with the manufacturer that the vinegar is not malt vinegar.
Glucose is gluten-free and safe for someone with celiac disease. It is a highly processed product, consisting of pure carbohydrate. Even when the source is wheat, no protein of any sort (including gluten) remains in the final product.
Among products which appear to be gluten-free based on ingredient labels, some have a higher risk of cross-contact with gluten, and are better avoided unless certified or labeled gluten-free. These products are: oats, lentils, and milled products made from grains, beans, seeds or legumes (e.g. sorghum flour, garbanzo bean flour, ground flax). Otherwise, products whose ingredients indicate they are gluten-free should be safe to consume, but choosing certified gluten-free versions provides an extra level of assurance.
May contain” or “shared equipment” statements are voluntarily included on some products to alert wheat allergic consumers of the presence of wheat in a manufacturing facility, because people with wheat allergies can have a reaction to wheat fractions other than gluten, and there is no test available to detect these other fractions. The presence of wheat starch as an ingredient would be an example of where you might see a “Contains: Wheat” statement alongside a gluten-free claim. For purposes of choosing gluten-free products, these types of statements are not relevant. If you see this type of statement on a product that is certified gluten-free, the gluten-free labeling/certification means that it is gluten-free regardless of any “may contain” type statements and contains 10 ppm gluten or less.
Genetic testing is applicable to celiac disease since there is a genetic component to the condition. Non-celiac gluten sensitivity, on the other hand, is not thought to have a genetic component (although it does still remain an incompletely understood condition). Without having the genes associated with celiac disease it is virtually impossible to develop the condition. There are two main scenarios in which finding out whether a person carries the genes or not can be especially useful:
1) If a person has stopped eating gluten before having the antibody screening tests for celiac disease. It is always advised that this testing be done before giving up gluten, but this just does not always happen. Once a person feels better after becoming gluten-free, they are often reluctant to re-introduce gluten. So, the diagnostic screening tests for celiac disease will not provide meaningful results. Undergoing genetic testing for celiac disease can tell these individuals the following: if the test is positive, they at least know that they could have celiac disease. Since about a third of the general population carries the genes, but only one percent develop celiac disease, having the genes does not mean that celiac disease necessarily will develop. The test is more informative if it is negative: negative results tell a person that it is virtually impossible that they have, or will develop, celiac disease. [The test doesn’t shed any light on whether or not a person has non-celiac gluten sensitivity (NCGS). The first step to diagnosing NCGS is generally to rule out other possible causes of symptoms, including celiac disease.]
2) When a family member has been diagnosed with celiac disease. First degree relatives (children, parents, siblings) of those who have been diagnosed have a significantly higher chance of developing the condition, with prevalence ranging from 4 to 16%. In second degree relatives (uncles, aunts, nephews, nieces, grandparents, grandchildren, half siblings), the prevalence is about 2.5%. Since these relatives have a higher chance of developing celiac disease, some may wish to find out whether in fact they do carry the related genes: if so, then that tells them that celiac disease could potentially develop at some point in their lives. If an individual does not carry the genes, they know that it is virtually impossible for them to develop the condition in the future.
Genetic testing can be especially useful to parents who have celiac disease and want to know whether their children have even the possibility of developing the condition. Positive genetic tests tell them that monitoring should be ongoing (see Celiac Disease Testing in Children). Negative tests would mean that no further screening is necessary.
Glutinous rice is also known as sticky rice or sweet rice. Despite its name it is gluten-free, as are all varieties of rice. The term “glutinous” in this case means “sticky.” The proportion of different types of starches in rice varies by type of rice. In the case of glutinous or sticky rice, this proportion is such that the cooked product is actually sticker. Sticky rice is commonly used in various Asian cuisines in both savory and sweet dishes.
There is no doubt that switching over to gluten-free eating, cooking, and baking is a significant transition. Like most big changes, entering into this new gluten-free territory can be frustrating and challenging; but it can also be new and exciting. Look at your move into gluten-free food preparation as not only a necessity, but a culinary adventure. In addition to staying healthy, you’ll likely discover some delicious new ingredients and dishes that you might otherwise never have come across. Check out our new piece on “Gluten-Free Cooking & Baking Hacks” to get started.
For individuals who need to be gluten-free, oat milk needs to be assessed the same way whole oats are. Oats are inherently gluten-free, but there is a significant risk of cross-contact with gluten-containing grains during growing and/or processing. Therefore, oats should not be consumed unless they are certified gluten-free. Likewise, oat-based products such as oat milk should only be consumed if they are made from certified gluten-free oats. Although uncontaminated oats in moderate quantities are tolerated by most people with celiac disease, it is advised that you consult with your physician or dietitian before including oats – or, by extension, oat milk – in your gluten-free diet.
Since anything that goes into the mouth does need to be evaluated for gluten content, this is a good question. Alternatives to plastic like glass or stainless steel are of course safely gluten-free, but some straws are made to be biodegradable, and may include ingredients such as bamboo, corn starch, wheat straw or sugar cane. If you’re ordering a drink that’s likely to come with a straw, before ordering ask the staff what their straws are made from and whether they are gluten-free. Even many brands of straws made from wheat straw are gluten-free (straw is the stalk left over after the gluten-containing grain is harvested). There is potential for cross-contact of straw, but it is unlikely, and some straws sourced from wheat straw have tested at levels below the FDA’s 20 ppm cut-off. So, it makes sense to be cautious and ask questions. If in doubt, simply enjoy your drink without the straw.
Sourdough bread is gluten-free only when it is made from gluten-free grains. Some wheat-based sourdough breads have lower gluten content than other wheat-based bread, but they are absolutely not suitable for a gluten-free diet.
Numerous research studies have found that the hepatitis B vaccine is less likely to be effective in individuals with celiac disease. However, some research has also found that this is not the case for people in whom celiac disease is well controlled and who are compliant with the gluten-free diet. No standard recommendation exists regarding how to address this situation, and each individual case can vary depending on when the vaccine was received relative to initiation of the gluten-free diet and achievement of good celiac disease control. The best course of action is to discuss your (or your child’s) situation with your personal physician and healthcare team, and determine whether re-vaccination may be advised.
*Note that this un-responsiveness does not apply to other vaccines in individuals with CD; only to the hepatitis B vaccine.
Anania C, Olivero F, Spagnolo A, Chiesa C, Pacifico L. Immune response to vaccines in children with celiac disease. World J Gastroenterol. 2017 May 14; 23(18): 3205–321. Published online 2017 May 14. doi: 10.3748/wjg.v23.i18.3205 www.ncbi.nlm.nih.gov/pmc/articles/PMC5434426/. Accessed July 25, 2018.
Ertekin V, Tosun MS, Selimoglu MA. Is There Need for a New Hepatitis B Vaccine Schedule for Children with Celiac Disease? Hepat Mon.2011 Aug 1; 11(8): 634–637. www.ncbi.nlm.nih.gov/pmc/articles/PMC3227494/. Accessed July 25, 2018.
Ertem D, et al.The response to hepatitis B vaccine: does it differ in celiac disease? Eur J Gastroenterol Hepatol. 2010 Jul;22(7):787-93. 2010 Jul;22(7):787-93. DOI:10.1097/MEG.0b013e32832e9d41. Accessed July 25, 2018.
Leonardi S, Spina M, Spicuzza L, Rotolo N, La Rosa M. Hepatitis B vaccination failure in celiac disease: Is there a need to reassess current immunization strategies? Vaccine.[12 Aug 2009, 27(43):6030-6033]DOI: 10.1016/j.vaccine.2009.07.099 . Accessed July 25, 2018.
Park SD, et al. Failure to respond to hepatitis B vaccine in children with celiac disease. J Pediatr Gstroenterol Nutr.2007 Apr;44(4):431-5.
www.ncbi.nlm.nih.gov/pubmed/17414139. Accessed July 25, 2018.
Rostami, Kamran; Nejad, Rostami M. Vaccinations in Celiac Disease. Journal of Pediatric Gastroenterology and Nutrition: April 2013 – Volume 56 – Issue 4 – p 341–342 doi: 10.1097/MPG.0b013e31827af217. journals.lww.com/jpgn/Fulltext/2013/04000/Vaccinations_in_Celiac_Disease.1.aspx. Accessed July 25, 2018.
Vitaliti G, et al. Hepatitis B vaccine in celiac disease: Yesterday, today and tomorrow. World J Gastroenterol.2013 Feb 14; 19(6): 838–845. Published online 2013 Feb 14. doi: 10.3748/wjg.v19.i6.838. Accessed July 25, 2018.
During the first year after diagnosis more frequent follow-up is generally recommended, and after that, follow-up should generally occur on a yearly basis. Scheduling and specific components of follow-up visits should be discussed and determined with your personal physician/healthcare team, since each individual’s situation is unique. The screening blood tests done as part of the celiac diagnosis are a primary component of follow-up, since high antibody levels can indicate gluten exposure and incomplete healing. Follow-up with a dietitian knowledgeable about the gluten-free diet may also be advisable, especially if lab results indicate gluten exposure, and/or if there are particular nutritional deficiencies or concerns.
Bumping around on a rough “hay”/”straw” ride could cause particles to be propelled into the air. So, if the straw/hay from a gluten-containing grain did happen to contain some seed (and therefore gluten), it is possible that some air-borne gluten might be present.
Gluten-free individuals and families should take these factors into consideration when evaluating potential exposure to gluten.
Since either straw or hay can be sourced from wheat it is understandable that this question comes up. However, we do not believe this is a cause for concern. Here’s why.
First of all, what exactly are straw and hay? Straw is an agricultural by-product that consists of the dry stalks of cereal plants. Hay is generally defined as the entire plant that has been dried. Both can come from various types of plants, including wheat. Either may be used as part of the substrate for growing plants.
There are two parts to the question:
1) When straw or hay come from wheat (or another gluten-containing plant), do they contain gluten? 2) If they do, does this gluten make it into or cross-contact the final plant which is grown on the substrate that contains straw or hay?
Since straw is the stalk of the plant, and gluten is found in the seed, straw technically does not contain gluten, although the possibility of cross-contamination cannot be entirely ruled out. Hay is the whole dried plant, but it is generally harvested and dried before the seed develops, so again it is unlikely to contain gluten.
Even if a plant sprouts from a substrate that could potentially contain gluten (from straw or hay), the mature plant itself (i.e. the edible plant) would for the most part be physically removed and separate from the substrate/ growing surface. The concern would be possible cross-contact due to surface contamination. As all produce should be washed before eating, it is believed that this cleaning would remove any potential residues of gluten that could even potentially result from surface contamination.
Two specific types of produce we have received questions about are mushrooms and strawberries. Here is what we have found out:
According to the North American Strawberry Growers Association, hay is not used in strawberry production; straw may be used as a winter cover in northern climates to protect against cold as well as to keep the berries clean. It is very unlikely that there would be any gluten associated with the fruit at harvest time.
Hay or straw can be incorporated into a growing medium for mushrooms, along with other substances that together form a compost. The compost is put into a bed, on top of which goes the “mycelium” (which functions a bit like a root system) that produces the spores which are responsible for mushrooms’ reproductive process. On top of the mycelium goes a layer of peat moss, which creates a physical barrier. So, the root system may come in contact with the hay or straw in the compost, but the mushrooms do not. The “dirt” we see on mushrooms is peat moss, which is pasteurized, and is not a gluten-containing substance.