Are Gluten Sensitivity Rates Rising?
Very few US studies have been conducted to determine celiac disease prevalence, and even less for gluten sensitivity.
Celiac Disease Rates
The prevalence of celiac disease in the US ranges from 0.5 to 1.0%, similar to estimates in Europe. Although Mayo Clinic researcher Rubio-Tapia et al. stated that celiac disease was 'on the rise', this was based on estimates between 1948 and 1954 that increased from 0.2% to approximately 1% 45 years later. The lower rate may have been due to collecting data on 9133 healthy recruits accepted into military service from all over the country of various nationalities and comparing them to cohorts in Minnesota (MN, USA), where many families immigrated from Northern Europe. In another study, Olmsted county (MI, USA) residents diagnosed with celiac disease between 1950 and 2001 were identified through the Rochester Epidemiology Project. The overall annual incidence of celiac disease was 2.1 per 100,000, but increased from 0.9 per 100,000 in 1950–1989 to 3.3 per 100,000 in the 1990s, and 9.1 per 100,000 in the final 2 years of the study. A previous 1974 survey revealed very low rates (1 out of 501) compared with current rates, estimated at 1 out of 133.
Globally, one of the highest reported celiac disease rates of 5.6% was found in Saharawi, an African population. In Europe, the higher prevalence rates of celiac disease occur in Ireland, Italy and Sweden. The prevalence also seems to have doubled in Finland from 1 to 2% between 1979 and 2000, without it being attributed to better detection.[31,32]
Among the elderly, Vilppula and colleagues reported a higher celiac disease prevalence of 2.13%. They screened 2815 individuals in Finland, aged 52–74 years, using IgA class tissue transglutaminase antibodies followed by small bowel biopsy in those testing positive. Rashtak and Murray reported that a third of the new celiac disease cases were being diagnosed in patients older than 65 years. A similar study in the elderly needs to be conducted to determine the prevalence of gluten sensitivity.
Gluten Sensitivity Rates
If a condition lacks a clear definition, then it becomes difficult, if not impossible, for its quantification in the population. Despite a few research reports that gluten sensitivity rates are rising, there has been no large-scale study in the USA to determine whether this is the case. Even if such a study were conducted, the first step would be to define gluten sensitivity, and this has not been done. Bizarro et al. estimated that for every one person with celiac disease, there are at least six to seven with gluten sensitivity.
Increased Demand for Gluten-free Foods
In a relatively crude fashion, the rising rates of gluten sensitivity are indirectly surfacing through the increasing market for gluten-free foods. Global sales are expected to reach US$4.3 billion by 2015, according to a recent analysis by Datamonitor. Approximately half of the global market is being generated by the USA, with Walmart introducing gluten-free foods to its shelves in 2005. The number of gluten-free booths at the American Dietetic Association's annual convention increased from three out of 394 (0.76%) in 2000, to 24 out of 364 (7%) in 2010 [American Dietetic Association, Pers. Comm.]. For the first time, national chain restaurants such as PF Chang® are adding gluten-free items to their menus, but gluten-free Big Macs® have been available in Finland for more than 20 years. Consumers pointing to increasing US demand for gluten-free products on the market suggest this is evidence for a gluten sensitivity problem emerging in the population. This empirical evidence is often dismissed by some professionals, a few of which suggest that the gluten-free diet is a 'fad diet'. This diet is very difficult and consists of eliminating any foods prepared with flours or foods derived from wheat, oat rye or barley. That translates into no pizza, cakes, pies, cookies, pasta, cereals, bread or baked products of any kind made with regular wheat flour. It also includes many processed foods, such as potato chips or french fries, which have been fried in oil used to cook other breaded items. A single crumb through cross-contamination can cause problems. Who would want to go on this type of diet for life? Instead, the focus should be on the question: 'why are adults, who never had a problem with gluten their entire lives, now reacting to foods they used to eat every day?'
Expert Rev Gastroenterol Hepatol. 2012;6(1):43-55. © 2012 Expert Reviews Ltd.