Is Gluten-Free Right for Me?
Despite the low rates of gluten-related disorders, significant increase in a gluten free lifestyle, regardless of disease, has become evident. Multiple factors contribute to the $15.5 billion market (as of 2016) such as media, marketing and reports in medical and mainstream literature of clinical benefits to avoid gluten (Niland & Cash, 2018). However, lifelong gluten restricted diet is necessary for patients diagnosed with Celiac Disease (CD). CD is an enteropathy characterized by adaptive and innate immune responses resulting in intestinal inflammation and villous atrophy (DiGiacomo et al., 2013). While gluten avoidance may be beneficial for a subset population— such as celiac, non-celiac gluten sensitivity, gluten sensitive irritable bowel syndrome and obesity— high quality evidence in support of gluten avoidance that is not mediated by immune/inflammatory responses to gluten is limited and not definitive (Niland & Cash, 2018).
The majority of people that consume a gluten free diet (GFD) do so without confirmed medical diagnoses for reasons such as improved gastrointestinal and non-gastrointestinal symptoms, a perception that gluten is harmful, and/or weight loss. In support of this, US data from the National Health and Nutritional Examination Survey from 2009-2014 demonstrated GFD to be associated with decreased body weight over one year, lower waist circumference and higher HDL cholesterol. However no significant differences in metabolic syndrome or cardiovascular risk were evident (Niland & Cash, 2018). In my opinion, weight improvements correlated to GFD may be associated with lower caloric intake and better food choices overall due to more limited options and an emphasis on whole foods.
While weight loss might be one perceived benefit, adverse effects must be considered. Adhering to an unnecessarily strict gluten free diet can potentiate nutrient deficiencies and/or create an imbalance in the microbiota as well as decrease total diet adherence. Any restrictive diet may cause deficiencies and lack of fortification may increase that risk. It has been demonstrated that only 5% of gluten free products and breads contain all mandatory fortified nutrients (calcium, iron, niacin, thiamin and riboflavin). Additionally, production of these goods requires the outer layer of the grain to be removed, reducing the fiber content (Di Nardo et al., 2019). Higher intakes of fiber are attributed to greater production of short chain fatty acids (acetic and butyric acid) and lower counts of E.coli; while the opposite is true for low fiber intakes (Sanz, 2010).
In a small preliminary study of 10 healthy patients (non-celiac/ non-gluten sensitive) following a GFD for one month, fecal microbiota demonstrated a decrease in healthy populations of bacteria (bifidobacteria, b. longum, and lactobacillus) while unhealthy populations such as E.coli and Enterobacteriaceae increased. This dysbiosis favored overgrowth of opportunistic pathogenic bacteria, partially explained by the reduction in polysaccharides that normally would reach the distal portion of the colon undigested. The reduced supply reduces the energy source of bacteria that encode enzymes specialized for utilization of non-digestible carbohydrates, allowing unhealthy populations to colonize (Sanz, 2010).
It can be tempting to follow diet trends that are roundly supported by the media, both mainstream and social. However, burgeoning market trends are no substitute for evidence-based nutrition. Making blanket statements and extrapolating data disregards the need for individuality, diet adherence and economic viability.
References
Di Nardo, Giovanni Pia Villa, Maria, Conti, L., Ranucci, G., Pacchiarotti, C., Principessa, L., Raucci, U., & and Pasquale Parisi. (2019). Nutritional deficiencies in children with celiac disease resulting from a gluten-free diet: A systematic review. Nutrients, 11(7), 1588. Retrieved from https://www-ncbi-nlm-nih-gov.uws.idm.oclc.org/pmc/articles/PMC6683263/
DiGiacomo, Daniel V. Tennyson, Christina A. Peter H. Green & Ryan T. Demmer. (2013). Prevalence of gluten-free diet adherence among individuals without celiac disease in the USA: Results from the continuous national health and nutrition examination survey 2009–2010. Scandinavian Journal of Gastroenterology, 48(8), 921-925. Retrieved from https://www-tandfonline-com.uws.idm.oclc.org/doi/full/10.3109/00365521.2013.809598
Niland, Benjamin and Cash, Brooks D. (2018). Health benefits and adverse effects of a gluten-free diet in Non–Celiac disease patients. Gastroenterol Hepatol, 14(2), 82-91. Retrieved from https://www-ncbi-nlm-nih-gov.uws.idm.oclc.org/pmc/articles/PMC5866307/
Sanz, Y. (2010). Effects of a gluten-free diet on gut microbiota and immune function in healthy adult humans. Gut Microbes, 1(3), 135-137. Retrieved from https://www-ncbi-nlm-nih-gov.uws.idm.oclc.org/pmc/articles/PMC3023594/