A recent study, published in the BMC Gastroenterology, investigated whether food antibodies can be used to diagnose milk and wheat intolerance. The researchers explored the association between serum antibodies against food antigens with perceived milk and wheat intolerance in people with morbid obesity.

Milk and wheat intolerance is among the most commonly reported food intolerances worldwide. It is, however, difficult to obtain precise numbers of people affected by food intolerance since the studies rely on self-reported sensitivities to these foods. While reliable diagnostic tests exist for food allergies, there are no reliable tests for food intolerances. Measurement of serum levels of food antibodies is gaining popularity as a laboratory test for food intolerance. For instance, the presence of IgG and IgA (Immunoglobulin G and A) antibodies against casein and gliadin (milk and wheat proteins) is an indication of milk and wheat intolerance respectively. On the contrary, some studies suggest that presence of these antibodies reflects immunological tolerance to corresponding foods when an individual is exposed to those foods.

What are Milk and Wheat Intolerances?

Milk and wheat are the main triggers associated with food-induced gastrointestinal disorders such as irritable bowel syndrome (IBS). People with morbid obesity, defined as having a body mass index (BMI) greater than 40 kg/m2 or a BMI of 35 kg/m2 or higher who also experiences obesity-related complications such as diabetes and hypertension, have a high prevalence of gastrointestinal disorders including IBS. In people with milk or wheat intolerance, exposure to milk or wheat proteins such as casein and gliadin initiates an inflammatory response, which over time damages the intestinal lining of the bowel. Chronic inflammation compromises the bowel’s ability to absorb nutrients and over time the permeability of the gut increases leading to a leaky gut. This could also result in increased passage of food antibodies through the gut.

A recent study, published in the BMC Gastroenterology, investigated the association between perceived milk and wheat intolerance and the IgG and IgA antibodies against milk and wheat proteins in morbidly obese people with gastrointestinal complaints. In addition, the study explored the association between perceived milk/wheat intolerance and parameters such as intake of offending foods, IBS, and severity of gastrointestinal complaints.

This cross-sectional study conducted in Norway, recruited 97 participants with morbid obesity. The average age of the participants was 45 years and 70 of the participants had gastrointestinal problems. The researchers rated the degree of gastrointestinal complaints and recorded food induced gastrointestinal symptoms with the help of questionnaires. The participants completed food frequency questionnaires (FFQ) to measure daily intake of food.

The researchers performed laboratory tests to evaluate the serum concentrations of IgG antibodies against cow’s milk, cheese, wheat, and gluten. The scientists also measured serum concentrations of IgA antibodies against casein and Gliadin. Twenty-five of the participants had IBS; 22 and 20 reported milk and wheat intolerance respectively while 11 had a perceived intolerance to both milk and wheat. The researchers compared the levels of IgG and IgA antibodies against milk and wheat in participants with gastrointestinal complaints.

Antibody Levels Could Not Predict Milk or Wheat Intolerance

The statistical analysis revealed no significant difference in relevant food antibodies in the participants with and without perceived milk and wheat intolerance. An estimation of the dietary intake of milk and wheat showed that the consumption of milk or dairy was lower but statistically significant in participants with perceived milk intolerance compared with participants without perceived milk intolerance. However, there was no difference observed in wheat consumption between those with or without perceived wheat intolerance. Furthermore, the results did not reveal a significant correlation between the food antibodies and type or severity of gastrointestinal symptoms.

Hypothyroidism and Wheat Intolerance

Interestingly, post-hoc analysis showed a correlation between hypothyroidism and wheat intolerance. Past research has presented evidence for a correlation between celiac disease and thyroid disease, but there is little known about an association between food intolerance and thyroid disease. This study found a significant correlation between antibodies against wheat and hypothyroidism suggesting that hypothyroidism was a more common occurrence in participants with perceived intolerance to wheat.

Additionally, the results of this study did not find a correlation between increased gut permeability and serum concentrations of food antibodies. The authors suggest that there may be other underlying mechanisms responsible for perceived wheat intolerance.

Some of the main strengths of this study include the use of clearly formulated questionnaires, the exclusion of patients with celiac disease, food intolerance based on perceived gastrointestinal intolerance, and a more practical clinical setting used to perform the study. However, inaccuracies in dietary reports due to recall bias and no access to the exact amounts of grains or wheat consumed by the participants constitute the main limitations of the study.

No Association between Perceived Intolerance and Antibodies

In conclusion, the researchers found no association between perceived milk and wheat intolerance and IgG and IgA food antibodies in morbid obese participants. Therefore, the presence of food antibodies does not correlate with a corresponding food intolerance. The authors express that there is not enough support for the use of food antibody levels in planning dietary interventions for morbidly obese people with milk and wheat intolerance.

Written by Preeti Paul, MS Biochemistry

Reference: Kvehaugen et al. Is perceived intolerance to milk and wheat associated with corresponding IgG and IgA food antibodies? A cross sectional study in subjects with morbid obesity and gastrointestinal symptoms. BMC Gastroenterology (2018) 18:22. DOI 10.1186/s12876-018-0750-x