Most gluten-free people can have mustard flour in small amounts, as long as the mustard flour is pure and not contaminated with gluten grains during processing. Mustard flour is naturally gluten-free, but cross-contamination is possible if it is processed in facilities that also handle wheat or other gluten grains. Those with celiac disease or severe gluten sensitivity should exercise caution and closely inspect the source and processing methods of any mustard flour products.
What is Mustard Flour?
Mustard flour is made by grinding mustard seeds into a fine powder. It can be produced from black, brown, or yellow mustard seeds. Mustard flour has an intensely pungent, spicy flavor and is commonly used as a seasoning or condiment in cooking. It is especially popular in Indian cuisine.
Some key facts about mustard flour:
- Naturally gluten-free – mustard seeds do not contain gluten.
- Adds flavor and heat to dishes.
- Has a strong, sharp taste – a little goes a long way.
- Yellow mustard flour is the mildest; brown is moderately spicy; black is the most pungent.
- May be contaminated with gluten if processed improperly.
- Higher in protein than wheat flour.
Is Mustard Flour Gluten-Free?
Mustard flour is naturally gluten-free. Gluten is a protein found in grains like wheat, barley, and rye. Since mustard seeds are not related to these grains, pure mustard flour does not inherently contain gluten.
However, potential sources of gluten contamination include:
- Cross-contact from gluten-containing grains processed in the same facility.
- Addition of wheat flour or other gluten ingredients.
- Use of gluten-containing stabilizers or preservatives.
Reputable brands that specialize in gluten-free products will process mustard flour in dedicated facilities and test final products to verify non-detectable levels of gluten. When made properly, mustard flour can be considered gluten-free according to FDA standards (under 20 ppm of gluten).
Reading Mustard Flour Labels
When purchasing mustard flour, check the label closely for:
- “Gluten-free” seal or certification.
- Statement of being produced in a gluten-free facility.
- List of ingredients – should only list “mustard flour.”
- Allergen info – should not list wheat, barley, rye or malt.
- Note cross-contamination risks if processed in shared equipment.
Reputable brands will be transparent about production methods and testing. When in doubt, contact the manufacturer.
Is Mustard Flour Safe for People with Celiac Disease?
For people with celiac disease, non-contaminated mustard flour that tests below 20ppm of gluten is considered safe in moderate amounts. One study found that consuming up to 100g per day of wheat starch containing below 20ppm gluten did not cause adverse effects in most celiac patients. 
However, individual sensitivity levels vary. Some people with celiac react to much smaller amounts of gluten than the FDA threshold. Using prudence with all gluten-free labeled products is advised, especially when first reintroducing formerly gluten-containing foods.
Starting with small serving sizes of mustard flour and monitoring for symptoms is recommended. Those who are extremely sensitive may want to avoid mustard flour, as zero contamination can never be fully guaranteed.
Potential Issues with Mustard Flour for Celiac Patients
While pure, tested mustard flour itself should not cause problems, there are some considerations:
- Cross-contamination from other ingredients mixed into the final product.
- Unable to verify source and processing method in restaurant/commercial foods containing mustard flour as an ingredient.
- Variability in gluten sensitivity – those with celiac react at different gluten thresholds.
- Trace amounts below testing detection levels may still cause issues for some.
Using known trusted brands and limiting intake to occasional small amounts can help reduce risks. But caution is still warranted.
Is Mustard Flour Safe for People with Non-Celiac Gluten Sensitivity?
For those with non-celiac gluten sensitivity, mustard flour that tests below 20ppm should also be safe in moderation.
However, people with NCGS often report reacting to even small traces of gluten. One study found 88% of those with NCGS reacted to only 10mg of gluten per day over 3 days.  Other research suggests the threshold may be around 25-50mg. 
Since the exact gluten tolerance level in NCGS patients is unclear, and amounts below 20ppm could potentially trigger symptoms, caution is advised when using any gluten-free labeled product. Some people with NCGS choose to avoid all foods with gluten-free labeling just to be safe.
Beginning with small amounts of mustard flour and closely monitoring symptoms may help determine individual tolerance. But for highly sensitive individuals, avoiding it altogether may be appropriate.
What About an Allergy to Mustard Seeds?
While gluten is the main concern for most people in regards to mustard flour, it’s important to note that mustard flour is not safe for anyone with an allergy to mustard seeds themselves.
Mustard allergies are relatively rare but can cause potentially serious reactions. Symptoms may include:
- Tingling or burning sensations in the mouth
- Hives, itching, or skin rashes
- Swelling of lips, face, tongue, throat
- Wheezing, nasal congestion, trouble breathing
- Headache, dizziness, stomach pain, vomiting, diarrhea
Those diagnosed with a mustard allergy will need to strictly avoid all forms of mustard, including mustard flour. Checking labels for mustard ingredients is vital.
How Much Mustard Flour Can a Gluten-Free Diet Have?
There are no official recommendations for how much mustard flour is safe to consume on a gluten-free diet. The FDA does not set a daily limit for residual gluten consumption. The “safe” amount depends on individual sensitivities.
However, most experts suggest limiting intake of any questionable gluten-free foods to help reduce risk. General guidelines include:
- Limit mustard flour to occasional use, not daily.
- Keep servings small. Mustard flour is potent; a little goes a long way.
- Avoid other sources of gluten for at least that day.
- Watch closely for symptom reactions.
Consuming a variety of naturally gluten-free whole foods allows room for some sparing use of processed items like mustard flour. Those who are most sensitive may decide avoiding it completely is the safest option. Discuss incorporation into your diet with your healthcare provider.
What Can You Make with Mustard Flour?
Here are some recipe ideas using mustard flour:
Marinades, Rubs & Sauces
- Barbecue sauce
- Hot pepper sauce
- Dijon mustard
- Salad dressing
- Marinated chicken, pork, or beef
- Spice rubs for roasted vegetables
- Seafood marinades
- Curries, dals & stews
- Rice or quinoa dishes
- Sautéed greens
- Onion or cabbage slaw
- Potato salad
- Popcorn seasoning
- Gluten-free bread
- Flour blends
Start with about 1/2 to 1 teaspoon mustard flour for every 1 cup of dry mix or 1 pound of meat. Add more to taste. It packs a punch! Blend with other herbs and spices to balance the heat.
The Bottom Line
Pure mustard flour that has been properly processed in dedicated gluten-free facilities should be safe in moderate amounts for most gluten-free consumers. But due to potential cross-contamination risks and individual sensitivity differences, starting slowly and monitoring intake is important.
For those with celiac disease or NCGS who are highly sensitive, avoiding it or using extreme caution may be appropriate. Anyone with a mustard seed allergy will need to avoid all mustard products.
When used sparingly with care in the context of an overall healthy gluten-free diet, mustard flour can provide flavor diversity without compromising health or safety. But as with any processed specialty product, quality control is key.
 Catassi, C., Fabiani, E., Iacono, G., D’Agate, C., Francavilla, R., Biagi, F., Volta, U., Accomando, S., Picarelli, A., De Vitis, I. and Pianelli, G. (2007), A Prospective, Double-Blind, Placebo-Controlled Trial to Establish a Safe Gluten Threshold for Patients with Celiac Disease. The American Journal of Clinical Nutrition, 85(1), 160–166. https://doi.org/10.1093/ajcn/85.1.160
 Biesiekierski JR, Peters SL, Newnham ED, Rosella O, Muir JG, Gibson PR. No Effects of Gluten in Patients With Self-Reported Non-Celiac Gluten Sensitivity After Dietary Reduction of Fermentable, Poorly Absorbed, Short-Chain Carbohydrates. Gastroenterology. 2013;145(2):320-328.e3. doi:10.1053/j.gastro.2013.04.051
 Catassi, Carlo, et al. “Non-Celiac Gluten Sensitivity: The New Frontier of Gluten Related Disorders.” Nutrients 5.10 (2013): 3839–3853. Web.