Gluten-free diet
In blinded challenges, 16% of people with self-reported gluten sensitivity reacted specifically to gluten, and fructans or expectation explained symptoms in several trials. Two IBS trials showed no significant benefit, and cyclists' performance did not change. People on the diet had higher blood mercury and urine arsenic, with shortfalls of fiber, vitamin D, iron, B12 and folate reported.
- Status
- A dietary pattern, not a regulated product.
- Also called
- gluten free diet, GFD, gluten-free eating, wheat-free diet, gluten avoidance, going gluten-free, non-celiac gluten sensitivity diet
- Followed for
- gut symptoms, bloating, gluten sensitivity, IBS, weight loss, athletic performance, heart health, energy
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Shown to help0
No benefit shown in research yet.
Reported risks8
- LimitedLinked to low fiber intake, about 19 g a day, in adults with celiac disease on a gluten-free diet.
- LimitedLinked to insufficient vitamin D intake at all ages in people with celiac disease on a gluten-free diet.
- LimitedLinked to insufficient calcium intake in adolescents with celiac disease on a gluten-free diet.
- LimitedLinked to insufficient magnesium intake in adolescents with celiac disease on a gluten-free diet.
- LimitedLinked to more iron deficiency in people with non-celiac gluten or wheat sensitivity than in controls, and to low iron intake in adolescents with celiac disease.
- LimitedLinked to more vitamin B12 deficiency in people with non-celiac gluten or wheat sensitivity than in controls.
- LimitedLinked to more folate deficiency in people with non-celiac gluten or wheat sensitivity than in controls.
- LimitedLinked to higher blood mercury and lead and urine arsenic in people on a gluten-free diet, including people without celiac disease.
What people follow it for, and what was found
Mixed results2
Symptoms in self-reported gluten sensitivity
Mixed results: about 16% to 30% of people with self-reported gluten sensitivity reacted to blinded gluten, and placebo often caused similar symptoms.
Compared with gluten given blind against a placebo of gluten-free products, xylose, whey protein, rice or corn starch [1]; gluten re-challenge, with or without a placebo [2]; gluten-free placebo bread and muffins on the same gluten-free diet [3]; whey protein or no added protein after a low-FODMAP diet, against gluten [4]; fructans and a placebo in muesli bars, against gluten [5]; gluten-free against gluten-containing oat bread, with and without the expectation of gluten [6]
The numbers and sources
- Effect
- Across 10 double-blind placebo-controlled challenge trials (1,312 adults), 38 of 231 patients (16%) showed gluten-specific symptoms, and 40% of these also reacted to placebo [1]. In 11 re-challenge studies, 30% relapsed on gluten (range 7% to 77%), and relapse did not differ significantly from placebo [2]. In one trial, 68% on gluten and 40% on placebo said symptoms were not adequately controlled [3]. After 2 weeks on a low-FODMAP diet, gluten-specific effects appeared in 8% of participants [4]. In 59 people, fructans raised IBS symptom scores more than gluten, and gluten did not differ from placebo [5]. In 83 people, symptoms were highest when people both expected and received gluten, and actual gluten without that expectation did not differ from gluten-free bread [6].
- Population
- Adults with self-reported non-celiac gluten sensitivity, many with IBS, with celiac disease excluded [1][2][3][4][5][6].
- Sources
- [1], [2], [3], [4], [5], [6]
- Caveats
- Trials varied in gluten dose (2 to 52 g a day), challenge length and placebo [1]. With the Salerno criteria, 40% relapsed on gluten against 24% on placebo [2]. The trial in [6] was partly funded by the bakery and wheat industry.
Weight and metabolic markers
One 3-month trial in fatty liver disease found adding a gluten-free diet to lifestyle training lowered fasting glucose and triglycerides more, with no difference in BMI or waist.
Compared with lifestyle change training alone, in Iranian patients with fatty liver disease [9]
The numbers and sources
- Effect
- Between groups, only fasting blood sugar and triglycerides were lower in the gluten-free group. BMI, waist circumference, blood pressure, liver tests and steatosis grade improved similarly in both groups [9].
- Population
- 60 adults with nonalcoholic fatty liver disease [9].
- Sources
- [9]
- Caveats
- Open-label, small and 3 months long [9].
Not shown to help3
IBS symptoms
Limited evidence: two trials in IBS did not show a significant reduction in global symptoms on a gluten-free diet against a gluten-containing control.
Compared with the same diet spiked with gluten [7]
The numbers and sources
- Effect
- In 2 RCTs (111 participants), global symptoms were lower on a gluten-free diet than on a control diet (RR 0.42, 95% CI 0.11 to 1.55, I² 88%), a difference that was not statistically significant [7].
- Population
- People with IBS who had responded to a gluten-free diet, then randomized to continue it or have gluten added [7].
- Sources
- [7]
- Caveats
- GRADE quality was very low [7].
Athletic performance
One small crossover trial in cyclists without celiac disease found no change in time-trial performance, gut symptoms or inflammation markers after 7 days gluten-free.
Compared with the same diet with gluten-containing food bars, in the same cyclists [8]
The numbers and sources
- Effect
- Time-trial work was 245.4 kJ on the gluten-containing diet and 245.0 kJ on the gluten-free diet (P = 0.37). Gut symptoms, well-being, the intestinal injury marker IFABP and cytokine responses did not differ [8].
- Population
- 13 competitive endurance cyclists without celiac disease or IBS [8].
- Sources
- [8]
- Caveats
- Thirteen people for 7 days [8].
Heart disease
In cohort data, gluten intake was not linked to coronary heart disease over 26 years in 110,017 adults without celiac disease.
Compared with US nurses and health professionals in the lowest fifth of gluten intake [10]
The numbers and sources
- Effect
- The highest fifth of gluten intake had a multivariable hazard ratio for coronary heart disease of 0.95 (95% CI 0.88 to 1.02) against the lowest fifth. After adjusting for refined grains, so that the remaining gluten tracked whole grains, higher gluten intake was linked to lower risk (HR 0.85, 95% CI 0.77 to 0.93) [10].
- Population
- 64,714 women and 45,303 men in two US cohorts of health professionals, observational [10].
- Sources
- [10]
- Caveats
- Observational. Gluten was estimated from food questionnaires, and the study measured gluten intake, not people following a gluten-free diet [10].
How trials defined it
Gluten challenge trials gave 2 to 52 g of gluten a day for 1 day to 6 weeks [1], for example 16 g a day against 2 g a day and whey placebo [4], two slices of bread and a muffin a day for up to 6 weeks [3], or 5.7 g of gluten against 2.1 g of fructans in muesli bars for 7 days [5]. The cyclist trial added food bars with or without 16 g of wheat gluten a day to a gluten-free diet for 7 days [8]. The fatty liver trial added a gluten-free diet to lifestyle training for 3 months [9].
Risks
Reported risks8
Fiber
Linked to low fiber intake, about 19 g a day, in adults with celiac disease on a gluten-free diet.
The numbers and sources
- Effect
- Across 38 studies (2,114 patients), adults on a gluten-free diet ate 18.9 g of fiber a day (95% CI 16.5 to 21.4), which the authors class as insufficient [11].
- Population
- Adults and children with celiac disease on a gluten-free diet [11].
- Sources
- [11]
- Caveats
- People with celiac disease, not people without it who choose the diet. Intake, not blood status [11].
Vitamin D
Linked to insufficient vitamin D intake at all ages in people with celiac disease on a gluten-free diet.
The numbers and sources
- Effect
- Vitamin D intake was insufficient in all age groups of celiac patients on a gluten-free diet [11].
- Population
- Adults and children with celiac disease in 38 studies [11].
- Sources
- [11], [12]
- Caveats
- Intake, not status. In a review of deficiency studies, people with celiac disease on the diet had a lower risk of vitamin D deficiency than those with untreated disease [12].
Calcium
Linked to insufficient calcium intake in adolescents with celiac disease on a gluten-free diet.
Magnesium
Linked to insufficient magnesium intake in adolescents with celiac disease on a gluten-free diet.
Iron
Linked to more iron deficiency in people with non-celiac gluten or wheat sensitivity than in controls, and to low iron intake in adolescents with celiac disease.
The numbers and sources
- Effect
- In a review of micronutrient deficiencies associated with a gluten-free diet, people with non-celiac gluten or wheat sensitivity had a higher risk of iron deficiency than controls [12]. Iron intake was particularly insufficient in adolescents with celiac disease on the diet [11].
- Population
- 46 observational studies [12]; children and adolescents with celiac disease [11].
- Sources
- [11], [12]
- Caveats
- Very low quality evidence, and the abstract gives no rates. In celiac disease, the diet went with a lower risk of iron deficiency than untreated disease [12].
Vitamin B12
Linked to more vitamin B12 deficiency in people with non-celiac gluten or wheat sensitivity than in controls.
The numbers and sources
- Effect
- In a review of micronutrient deficiencies associated with a gluten-free diet, people with non-celiac gluten or wheat sensitivity had a higher risk of vitamin B12 deficiency than controls [12].
- Population
- 46 observational studies [12].
- Sources
- [12]
- Caveats
- Very low quality evidence. The abstract gives no rates and does not say how many were on the diet [12].
Folate
Linked to more folate deficiency in people with non-celiac gluten or wheat sensitivity than in controls.
The numbers and sources
- Effect
- In a review of micronutrient deficiencies associated with a gluten-free diet, people with non-celiac gluten or wheat sensitivity had a higher risk of folate deficiency than controls [12].
- Population
- 46 observational studies [12].
- Sources
- [12]
- Caveats
- Very low quality evidence. The abstract gives no rates and does not say how many were on the diet [12].
Arsenic, mercury and other metals
Linked to higher blood mercury and lead and urine arsenic in people on a gluten-free diet, including people without celiac disease.
The numbers and sources
- Effect
- In US national survey data, people on a gluten-free diet had higher blood mercury (1.37 against 0.93 mcg/L), lead (1.42 against 1.13 mcg/L) and cadmium (0.42 against 0.34 mcg/L), and higher urine arsenic (15.15 against 8.38 mcg/L). Among people without celiac disease, mercury, lead and arsenic were also higher [13]. In 35 children newly diagnosed with celiac disease, median urine arsenic rose from 3.3 to 13.6 µg/L after 6 months gluten-free [14] and was back to baseline at 12 months in the 21 retested [15]. Treated celiac patients had about four times the blood mercury of untreated patients [16].
- Population
- 11,354 US survey participants, 115 on a gluten-free diet and 101 of them without celiac disease [13]; children aged 2 to 18 with celiac disease [14][15]; 30 celiac patients and 20 controls [16].
- Sources
- [13], [14], [15], [16]
- Caveats
- Cross-sectional data or small cohorts. Arsenic levels were well below acutely toxic concentrations, and the effect of long-term exposure is unknown [14].
Supplements to consider
The nutrients research linked to this diet running short, each with its own page.
Fiber supplements
Limited Linked to low fiber intake, about 19 g a day, in adults with celiac disease on a gluten-free diet.
Vitamin D
Limited Linked to insufficient vitamin D intake at all ages in people with celiac disease on a gluten-free diet.
Calcium
Limited Linked to insufficient calcium intake in adolescents with celiac disease on a gluten-free diet.
Magnesium
Limited Linked to insufficient magnesium intake in adolescents with celiac disease on a gluten-free diet.
Iron
Limited Linked to more iron deficiency in people with non-celiac gluten or wheat sensitivity than in controls, and to low iron intake in adolescents with celiac disease.
Vitamin B12
Limited Linked to more vitamin B12 deficiency in people with non-celiac gluten or wheat sensitivity than in controls.
Folate
Limited Linked to more folate deficiency in people with non-celiac gluten or wheat sensitivity than in controls.
Claims tested and not found
- That gluten causes the symptoms in most people with self-reported gluten sensitivity. Only 16% showed gluten-specific symptoms in blinded challenges [1], and in one trial fructans, not gluten, raised symptoms [5].
- That going gluten-free improves endurance performance. Time-trial performance did not change in cyclists without celiac disease [8].
- That eating gluten raises heart disease risk in people without celiac disease. Gluten intake was not linked to coronary heart disease over 26 years [10].
Sources
- Molina-Infante J, Carroccio A. Suspected Nonceliac Gluten Sensitivity Confirmed in Few Patients After Gluten Challenge in Double-Blind, Placebo-Controlled Trials. Clinical Gastroenterology and Hepatology. 2017. https://doi.org/10.1016/j.cgh.2016.08.007
- Lionetti E, Pulvirenti A, Vallorani M, et al. Re-challenge Studies in Non-celiac Gluten Sensitivity: A Systematic Review and Meta-Analysis. Frontiers in Physiology. 2017. https://doi.org/10.3389/fphys.2017.00621
- Biesiekierski JR, Newnham ED, Irving PM, et al. Gluten causes gastrointestinal symptoms in subjects without celiac disease: a double-blind randomized placebo-controlled trial. The American Journal of Gastroenterology. 2011. https://doi.org/10.1038/ajg.2010.487
- Biesiekierski JR, Peters SL, Newnham ED, et al. 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. https://doi.org/10.1053/j.gastro.2013.04.051
- Skodje GI, Sarna VK, Minelle IH, et al. Fructan, Rather Than Gluten, Induces Symptoms in Patients With Self-Reported Non-Celiac Gluten Sensitivity. Gastroenterology. 2018. https://doi.org/10.1053/j.gastro.2017.10.040
- de Graaf MCG, Lawton CL, Croden F, et al. The effect of expectancy versus actual gluten intake on gastrointestinal and extra-intestinal symptoms in non-coeliac gluten sensitivity: a randomised, double-blind, placebo-controlled, international, multicentre study. The Lancet Gastroenterology & Hepatology. 2024. https://doi.org/10.1016/s2468-1253(23)00317-5
- Dionne J, Ford AC, Yuan Y, et al. A Systematic Review and Meta-Analysis Evaluating the Efficacy of a Gluten-Free Diet and a Low FODMAPs Diet in Treating Symptoms of Irritable Bowel Syndrome. The American Journal of Gastroenterology. 2018. https://doi.org/10.1038/s41395-018-0195-4
- Lis D, Stellingwerff T, Kitic CM, et al. No Effects of a Short-Term Gluten-free Diet on Performance in Nonceliac Athletes. Medicine & Science in Sports & Exercise. 2015. https://doi.org/10.1249/mss.0000000000000699
- Jazayeri M, Zarrin R, Mohammadi A, et al. Effects of gluten-free diet on metabolic syndrome components and anthropometric indices in patients with nonalcoholic fatty liver disease: An open-label randomized clinical trial. Arab Journal of Gastroenterology. 2026. https://doi.org/10.1016/j.ajg.2025.10.001
- Lebwohl B, Cao Y, Zong G, et al. Long term gluten consumption in adults without celiac disease and risk of coronary heart disease: prospective cohort study. BMJ. 2017. https://doi.org/10.1136/bmj.j1892
- Gessaroli M, Frazzoni L, Sikandar U, et al. Nutrient intakes in adult and pediatric coeliac disease patients on gluten-free diet: a systematic review and meta-analysis. European Journal of Clinical Nutrition. 2023. https://doi.org/10.1038/s41430-023-01280-0
- Russell LA, Alliston P, Armstrong D, et al. Micronutrient Deficiencies Associated with a Gluten-Free Diet in Patients with Celiac Disease and Non-Celiac Gluten or Wheat Sensitivity: A Systematic Review and Meta-Analysis. Journal of Clinical Medicine. 2025. https://doi.org/10.3390/jcm14144848
- Raehsler SL, Choung RS, Marietta EV, et al. Accumulation of Heavy Metals in People on a Gluten-Free Diet. Clinical Gastroenterology and Hepatology. 2018. https://doi.org/10.1016/j.cgh.2017.01.034
- Du N, Du N, Chang D, et al. Effect of Adopting a Gluten-Free Diet on Exposure to Arsenic and Other Heavy Metals in Children With Celiac Disease: A Prospective Cohort Study. The American Journal of Gastroenterology. 2024. https://doi.org/10.14309/ajg.0000000000003117
- Du N, Baek C, Rosen R, et al. Return to baseline arsenic concentrations after 1 year on gluten-free diet in children with celiac disease: A prospective cohort study. JPGN Reports. 2025. https://doi.org/10.1002/jpr3.70135
- Elli L, Rossi V, Conte D, et al. Increased Mercury Levels in Patients with Celiac Disease following a Gluten-Free Regimen. Gastroenterology Research and Practice. 2015. https://doi.org/10.1155/2015/953042