Wheat is the third most produced cereal grain in the world and is one of the most important staple foods for humans. However wheat also contains many anti-nutrients and has potential to cause severe harm and health issues in susceptible individuals.

The most famous harmful component of wheat is gluten. Gluten is a seed storage protein found in wheat. Gluten is not exclusive to wheat and is also found in rye and barley. The component of gluten that is implicated in pathogenesis of some diseases is gliadin. Gliadin binds and alters an enzyme in the cells of GI tract, and the result of this acts as a trigger for an autoimmune response. The inflammatory response triggered by gliadins causes a loss of villi, the finger-like projections into the lumen of the small intestines. This autoimmune reaction not only results in malabsorption and its various complications, but also causes other autoimmune disease and even cancer in some cases. If the patient is placed on a gluten-free diet all of this can be prevented, reversing the damage to intestines. Gluten is also implicated in wheat allergy.

Another possibly harmful substance is gluteomorphin, also called gliadomorphin. Gluteomorphin is not normally present in wheat, but is derived from the enzymatic digestion of the gliadin component of gluten protein. Although conclusive evidence is still lacking, some studies have suggested that gluteomorphin is absorbed in the circulation in children with autism and causes brain damage.

Maltodextrin is a commonly used food additive in production of sodas and candy. It can be derived from either corn or wheat. Wheat derived maltodextrin could bother individuals who are on a strict gluten-free diet. Although maltodextrin is almost always gluten-free due to extensive processing, it may still be mentioned on the label if wheat derived maltodextrin is used.

Wheat germ agglutinin (WGA) protects wheat from insects, yeast and bacteria by binding to N-acetyl-D-glucosamine and Sialic Acid. This N-acetyl-D-glucosamine is also found in the human body in many places. It reduces the digestibility and utilization of dietary proteins. WGA can cause direct damage to many tissues in the body. WGA can bind to the myelin sheaths of the nerves and cause neurotoxicity. WGA increases the synthesis of mediators of inflammation and is also immunotoxic. Recent research also points to the possibility of WGA being cytotoxic by interfering with gene expressions. It may also disrupt endocrine and gastrointestinal functions. WGA interferes with metabolism and growth of cell lining the gastrointestinal tract and induces hyperplastic and hypertrophic growth of small bowel.