SEARCH HEALTH STUDIES

Search Results

No Link Between Gluten and Brain Health

Misguided dieters may avoid gluten for fear of “grain brain,” and yet research suggests that these fears are unfounded. In a study of 13,494 women without celiac disease, there was absolutely no relationship between gluten and cognitive function. The authors confirm that “restricting dietary gluten for the purpose of maintaining or improving cognition is not warranted in the absence of celiac disease or established gluten sensitivity.”
JAMA Network Open. 2021 May 3;4(5):e2113020. doi: 10.1001/jamanetworkopen.2021.13020. (Wang Y et al.)

Unsubstantiated Health Beliefs Lead People to Avoid Gluten Unnecessarily

Following a gluten-free diet is required for those with celiac disease or medically diagnosed gluten sensitivities. Because gluten-free foods tend to be less nutritious and may raise the risk of nutrient deficiencies, researchers wanted to know what motivates people to avoid gluten when it is not medically necessary. In this study, 2,982 adults in the US without celiac disease were surveyed about their beliefs regarding gluten-free diets. Compared with people who eat gluten, people without celiac disease who avoid gluten are more likely to believe medically unsubstantiated claims (that gluten-free diets are more nutritious and can improve acne).  
Appetite. 2021 Jan 1; 156:104958. doi: 10.1016/j.appet.2020.104958 (Arslain K et al.)

Modern Wheat Does NOT Have More Gluten than Ancient Wheat

Over the past centuries, the yield production of wheat has dramatically increased around the globe, leaving some to wonder how the quality and gluten content of modern wheat compares to ancient varieties. This research analyzed more than 200 wheat lines from the 18th century through modern times. The results showed that modern breeds of wheat tend to have slightly higher starch and fiber levels, and lower protein content as well as lower levels of some minerals (iron, zinc, magnesium). In fact, the decreased gliadin: glutenin ratio in modern wheat indicates a decrease in celiac disease antigens in modern wheat, while the lower protein content indicates lower levels of gluten.
Nutrition Bulletin. 2020 Sept. doi:10.1111/nbu.12461. (Shewry PR et al.)

 

Kids with Celiac Disease Tend to Eat Less Fiber, More Saturated Fat on Gluten-Free Diet

Lifelong adherence to a gluten-free diet is a medical necessity for people with celiac disease. However, extra care must be taken to ensure that a gluten-free diet is nutritionally balanced. In this study, researchers analyzed the diets of 120 children with celiac disease who had been eating a gluten-free diet for at least 2 years, along with 100 age-and-gender-matched healthy children who didn’t avoid gluten. Those on a gluten-free diet ate significantly more saturated fat (contributing to 12.8% vs 8.8% of total calories) and significantly less fiber (12.6 g vs 15 g) daily than those not on a gluten-free diet.
Nutrients. 2020 Jan 4;12(1). pii: E143. doi: 10.3390/nu12010143.(Lionetti E et al.)

Going Gluten-Free Does Not Improve Digestive Symptoms in Healthy Volunteers

If you don’t have a medically-diagnosed problem with gluten, is there any benefit to going gluten-free? New research suggests not. In this study, scientists randomly assigned 28 people without medical problems with gluten to a gluten-free diet or a gluten-containing diet for 2 weeks. The gluten-containing diet did not generate any symptoms (diarrhea, reflux, constipation, fatigue, etc.) in these healthy volunteers. They concluded that because a gluten-free diet is often less healthy than a typical diet, “there is possibly clinical justification in actively discouraging people from starting it if they have no diagnosable sensitivity.”
Gastroenterology. 2019 September;157:881-883. doi: 10.1053/j.gastro.2019.05.015. (Croall ID et al.)

Gluten-Free Diet Not Appropriate without Medical Diagnosis

Gluten is a compound found naturally in wheat, barley, and rye that helps dough stretch and bread rise. Many misguided dieters today choose to go gluten-free, even though only about 1% of the population has celiac disease (an autoimmune disorder where gluten must be avoided). In this review, researchers analyzed studies on the nutritional adequacy of gluten-free diets. They found that gluten-free diets tend to have less fiber, calcium, magnesium, zinc, vitamin B12, folate, and vitamin D, and tend to have more saturated fat and exposure to arsenic. The researchers note that “the majority of persons adopting a [gluten-free diet] have no medical basis for doing so,” and that “only persons with [celiac disease], [wheat allergy], or [non celiac gluten-sensitivity] should follow a [gluten-free diet], and they should do so under medical supervision.”
Journal of Nutrition and Metabolism. 2019 Jul 1;2019:2438934. doi: 10.1155/2019/2438934. [Diez-Sampedro A et al.]

Gluten Free Kids' Foods No Healthier than Regular Kids' Foods

Many parents buy gluten-free foods for their kids because they think that those foods are healthier. But unless you have a medically-diagnosed reason to avoid gluten (such as celiac disease), evidence suggests otherwise. Researchers in Canada went to 2 major supermarket chains and purchased all foods marketed to kids (with the exception of candy, soda, and a few other “junk foods”) – 374 products total. They then analyzed the nutrition labels of the foods, to see how products marketed as gluten free stacked up to those not marketed as gluten free. For a more direct comparison, they then identified 43 gluten-free foods marketed to kids that had a non-gluten-free counterpart, and compared nutrition between the matched products. Overall, nutrition was poor among all kids’ products, gluten-free or not, and there were few significant differences. Specifically, products marketed as gluten-free had slightly lower levels of sodium, but slightly higher levels of added sugar. Additionally, a higher proportion of gluten-free products had high levels of trans fat. The researchers concluded that “[gluten-free] supermarket foods that are targeted at children are not nutritionally superior to regular child targeted foods and may be of greater potential concern because of their sugar content,” adding that “parents who substitute [gluten-free] products for their product equivalents (assuming [gluten-free] products to be healthier) are mistaken.”
Pediatrics. 2018 Aug;142(2). pii: e20180525. (Elliott C et al.)

Delayed Gluten Introduction May Be Linked with Type 1 Diabetes Risk

In a study of 8,676 babies with a genetic risk for type 1 diabetes, researchers took blood samples every 3 months for at least 9 months after birth and analyzed their diet. Every 1-month delay in gluten introduction was linked with a significantly higher risk of the immune system attacking the pancreatic cells that are important for blood sugar regulation (as measured by islet autoimmunity) as well as higher levels of insulin autoantibodies, which are predictors of type 1 diabetes. In fact, introducing gluten after 9 months was linked with a 57% higher risk of islet autoimmunity than introducing gluten between 4-9 months of age. The researchers suggest that the timing of gluten be studied further, so that healthcare providers can more confidently suggest a recommended window.
Diabetes Care. 2018 Mar;41(3):522-530. (Uusitalo U et al.)

Gluten Not Directly Responsible for Symptoms of Non-Celiac Gluten Sensitivity

Interest in a gluten-free diet has grown tremendously over the past decade. However, new research raises questions about whether gluten is a culprit of intestinal distress. In this study, researchers at the University of Oslo tested reactions to fructan (a compound found naturally in wheat and vegetables like onions, asparagus, and garlic) and gluten (a protein found naturally in wheat, barley, and rye). In a highly-controlled study of 59 people following a self-reported gluten-free diet, researchers tested patients’ symptoms after exposure to gluten, fructan, and a placebo.  Interestingly, 13 participants had significant symptoms after eating gluten, 24 had symptoms after eating fructan, and 22 had symptoms after eating a placebo, a food without gluten or fructan. There was no difference in GI symptoms after the gluten or placebo and more patients had reactions to the fructan as opposed to the gluten. The authors conclude that their findings weaken the use of the term “Non-Celiac Gluten Sensitivity,” and raise “doubts about the need for a gluten-free diet in such patients.
Gastroenterology. 2017 Nov 1. pii: S0016-5085(17)36302-3. (Skodje GI et al.)

Gluten Not Related to Heart Disease, but Avoiding Whole Grains Is

Unless you have celiac disease, you might want to rethink that gluten-free diet. In a study of more than 100,000 US adults without celiac disease, followed for more than 25 years, researchers found that eating gluten was not related to heart disease risk. In fact, the researchers caution that avoiding gluten may result in eating fewer whole grain foods, which may in turn pose a risk for heart disease.
BMJ. 2017 May 2;357:j1892. (Lebwohl B et al.)

Few Patients with Suspected Non-celiac Gluten Sensitivity Actually Show Gluten-Specific Symptoms

Many patients who respond well to a gluten free diet, but don’t test positive for celiac disease, are thought to have non-celiac gluten sensitivity. However, a closer look at this population is raising some doubts. Researchers in Spain analyzed data from 10 studies comprising 1312 adults, all of which were double blind, placebo controlled gluten challenges (meaning that neither the researchers nor the participants knew if they were getting a gluten-free diet or the gluten-containing placebo).  Only 16% of the non-celiac gluten sensitivity patients showed gluten-specific symptoms when exposed to the gluten-containing diet, and 40% of them had similar or increased symptoms when on the gluten-free control diet. The researchers conclude that these results “cast doubt on gluten as the culprit food component in most patients with presumptive [non-celiac gluten sensitivity].”  
Perspectives in Clinical Gastroenterology and Hepatology. 2017 Mar:15(3):339-348. (Molina-Infante J et al.) 

Low Gluten Diet Linked with Diabetes

For those without a medically diagnosed gluten issue (such as celiac disease), the support for gluten-free and low-gluten diets appears to be more fad than fact. In a study of nearly 200,000 health professionals, researchers at Harvard found that eating lower amounts of gluten is related to a higher risk for type 2 diabetes. In fact, those in the top 20% of gluten intake were 13% less likely to get type 2 diabetes over the 30-year study period, even after adjusting for family history, exercise habits, weight, and calorie intake. (Note that research presented at meetings is considered preliminary until published in a peer reviewed journal.)
Presented at the American Heart Association’s Epidemiology and Prevention / Lifestyle and Cardiometabolic Health 2017 Scientific Sessions. Portland, OR. March 9, 2017. (Zhong G et al.)

Pages